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Protein may be therapeutic target for AML
Credit: Lance Liotta
Researchers have found evidence to suggest that the phosphoinositide (PI) modulator PIP4K2A plays a key role in acute myeloid leukemia (AML).
PIs appear to control the transformation of hematopoietic stem cells into leukemic cells.
Some of these PIs switch on specific cell-signaling pathways, resulting in rapid growth and enhanced survival. Regulation of the PIs is carried out by a variety of proteins known as PI modulators.
“Little is known about the role of PI modulators in leukemia,” said Tim Somervaille, PhD, of The University of Manchester in the UK.
“We wanted to find out which ones were responsible for cell growth or survival in acute myeloid leukemia.”
He and his colleagues described this research in Oncogene.
The researchers performed a targeted knockdown screen of PI modulator genes in human AML cells, looking for genes required to sustain proliferation or prevent apoptosis.
They found that one PI modulator, PIP4K2A, was essential for the growth of leukemia. PIP4K2A knockdown resulted in leukemic cell death. This occurred in both murine MLL-AF9 AML cells and primary human AML cells.
Additional investigation showed that PIP4K2A knockdown resulted in the accumulation of the cyclin-dependent kinase inhibitors CDKN1A and CDKN1B, as well as G1 cell-cycle arrest and apoptosis. CDKN1A accumulation and apoptosis were partially dependent on activation of the mTOR pathway.
Fortunately, PIP4K2A knockdown did not adversely affect normal hematopoietic stem and progenitor cells from mice or human subjects. Neither clonogenic nor multilineage differentiation potential was affected.
“This makes [PIP4K2A] an ideal target for future drug development in leukemia,” Dr Somervaille concluded. 
Credit: Lance Liotta
Researchers have found evidence to suggest that the phosphoinositide (PI) modulator PIP4K2A plays a key role in acute myeloid leukemia (AML).
PIs appear to control the transformation of hematopoietic stem cells into leukemic cells.
Some of these PIs switch on specific cell-signaling pathways, resulting in rapid growth and enhanced survival. Regulation of the PIs is carried out by a variety of proteins known as PI modulators.
“Little is known about the role of PI modulators in leukemia,” said Tim Somervaille, PhD, of The University of Manchester in the UK.
“We wanted to find out which ones were responsible for cell growth or survival in acute myeloid leukemia.”
He and his colleagues described this research in Oncogene.
The researchers performed a targeted knockdown screen of PI modulator genes in human AML cells, looking for genes required to sustain proliferation or prevent apoptosis.
They found that one PI modulator, PIP4K2A, was essential for the growth of leukemia. PIP4K2A knockdown resulted in leukemic cell death. This occurred in both murine MLL-AF9 AML cells and primary human AML cells.
Additional investigation showed that PIP4K2A knockdown resulted in the accumulation of the cyclin-dependent kinase inhibitors CDKN1A and CDKN1B, as well as G1 cell-cycle arrest and apoptosis. CDKN1A accumulation and apoptosis were partially dependent on activation of the mTOR pathway.
Fortunately, PIP4K2A knockdown did not adversely affect normal hematopoietic stem and progenitor cells from mice or human subjects. Neither clonogenic nor multilineage differentiation potential was affected.
“This makes [PIP4K2A] an ideal target for future drug development in leukemia,” Dr Somervaille concluded.
Credit: Lance Liotta
Researchers have found evidence to suggest that the phosphoinositide (PI) modulator PIP4K2A plays a key role in acute myeloid leukemia (AML).
PIs appear to control the transformation of hematopoietic stem cells into leukemic cells.
Some of these PIs switch on specific cell-signaling pathways, resulting in rapid growth and enhanced survival. Regulation of the PIs is carried out by a variety of proteins known as PI modulators.
“Little is known about the role of PI modulators in leukemia,” said Tim Somervaille, PhD, of The University of Manchester in the UK.
“We wanted to find out which ones were responsible for cell growth or survival in acute myeloid leukemia.”
He and his colleagues described this research in Oncogene.
The researchers performed a targeted knockdown screen of PI modulator genes in human AML cells, looking for genes required to sustain proliferation or prevent apoptosis.
They found that one PI modulator, PIP4K2A, was essential for the growth of leukemia. PIP4K2A knockdown resulted in leukemic cell death. This occurred in both murine MLL-AF9 AML cells and primary human AML cells.
Additional investigation showed that PIP4K2A knockdown resulted in the accumulation of the cyclin-dependent kinase inhibitors CDKN1A and CDKN1B, as well as G1 cell-cycle arrest and apoptosis. CDKN1A accumulation and apoptosis were partially dependent on activation of the mTOR pathway.
Fortunately, PIP4K2A knockdown did not adversely affect normal hematopoietic stem and progenitor cells from mice or human subjects. Neither clonogenic nor multilineage differentiation potential was affected.
“This makes [PIP4K2A] an ideal target for future drug development in leukemia,” Dr Somervaille concluded.
Protein interaction may be therapeutic target for AML
University of Queensland
Inhibiting the interaction of 2 proteins can prevent the development of acute myeloid leukemia (AML), according to a study published in Blood.
Researchers found evidence to suggest the “docking” of one protein, Myb, with another, p300, is essential for AML development.
“Our data identifies the critical role of this Myb-p300 interaction and shows that the disruption of this interaction could lead to a potential therapeutic strategy,” said Tom Gonda, PhD, of the University of Queensland’s School of Pharmacy in Woolloongabba, Queensland, Australia.
“This finding could lead to our team developing a drug to block this interaction and stop the growth of not only acute myeloid leukemia cells but probably the cells of other types of leukemia as well.”
Dr Gonda and his colleagues conducted this research using cells from Booreana mice, which carry a mutant allele of Myb, as well as cells from wild-type mice.
Experiments showed that the Myb-p300 interaction was necessary for in vitro transformation by the oncogenes AML1-ETO, AML1-ETO9a, MLL-ENL, and MLL-AF9.
The researchers also transduced cells from Booreana mice and wild-type mice with either AML1-ETO9a or MLL-AF9 retroviruses and transplanted the cells into irradiated mice. The cells from wild-type mice generated leukemia in the recipients, but the Booreana cells did not.
Lastly, the team performed gene expression analyses to gain more insight into the Myb-p300 relationship. They found that several genes already implicated in myeloid leukemogenesis and hematopoietic stem cell function are regulated in an Myb-p300-dependent manner.
The researchers therefore concluded that the Myb-p300 interaction is important to myeloid leukemogenesis. And disrupting this interaction could prove useful in the fight against AML.
Dr Gonda pointed out, however, that the Myb protein is produced by the MYB oncogene. And although this oncogene is required for the continued growth of leukemia cells, it is also essential for normal blood cell formation.
“[S]o we need an approach for targeting it that won’t completely disrupt normal blood cell production,” he said. “Our research shows that normal blood cells can continue to form even when the Myb-p300 interaction is unable to occur, suggesting that a drug that blocks the interaction could be safe for use in patients.”
Dr Gonda and his colleagues are also planning to examine the possibility of targeting genes and proteins that work downstream of MYB.
University of Queensland
Inhibiting the interaction of 2 proteins can prevent the development of acute myeloid leukemia (AML), according to a study published in Blood.
Researchers found evidence to suggest the “docking” of one protein, Myb, with another, p300, is essential for AML development.
“Our data identifies the critical role of this Myb-p300 interaction and shows that the disruption of this interaction could lead to a potential therapeutic strategy,” said Tom Gonda, PhD, of the University of Queensland’s School of Pharmacy in Woolloongabba, Queensland, Australia.
“This finding could lead to our team developing a drug to block this interaction and stop the growth of not only acute myeloid leukemia cells but probably the cells of other types of leukemia as well.”
Dr Gonda and his colleagues conducted this research using cells from Booreana mice, which carry a mutant allele of Myb, as well as cells from wild-type mice.
Experiments showed that the Myb-p300 interaction was necessary for in vitro transformation by the oncogenes AML1-ETO, AML1-ETO9a, MLL-ENL, and MLL-AF9.
The researchers also transduced cells from Booreana mice and wild-type mice with either AML1-ETO9a or MLL-AF9 retroviruses and transplanted the cells into irradiated mice. The cells from wild-type mice generated leukemia in the recipients, but the Booreana cells did not.
Lastly, the team performed gene expression analyses to gain more insight into the Myb-p300 relationship. They found that several genes already implicated in myeloid leukemogenesis and hematopoietic stem cell function are regulated in an Myb-p300-dependent manner.
The researchers therefore concluded that the Myb-p300 interaction is important to myeloid leukemogenesis. And disrupting this interaction could prove useful in the fight against AML.
Dr Gonda pointed out, however, that the Myb protein is produced by the MYB oncogene. And although this oncogene is required for the continued growth of leukemia cells, it is also essential for normal blood cell formation.
“[S]o we need an approach for targeting it that won’t completely disrupt normal blood cell production,” he said. “Our research shows that normal blood cells can continue to form even when the Myb-p300 interaction is unable to occur, suggesting that a drug that blocks the interaction could be safe for use in patients.”
Dr Gonda and his colleagues are also planning to examine the possibility of targeting genes and proteins that work downstream of MYB.
University of Queensland
Inhibiting the interaction of 2 proteins can prevent the development of acute myeloid leukemia (AML), according to a study published in Blood.
Researchers found evidence to suggest the “docking” of one protein, Myb, with another, p300, is essential for AML development.
“Our data identifies the critical role of this Myb-p300 interaction and shows that the disruption of this interaction could lead to a potential therapeutic strategy,” said Tom Gonda, PhD, of the University of Queensland’s School of Pharmacy in Woolloongabba, Queensland, Australia.
“This finding could lead to our team developing a drug to block this interaction and stop the growth of not only acute myeloid leukemia cells but probably the cells of other types of leukemia as well.”
Dr Gonda and his colleagues conducted this research using cells from Booreana mice, which carry a mutant allele of Myb, as well as cells from wild-type mice.
Experiments showed that the Myb-p300 interaction was necessary for in vitro transformation by the oncogenes AML1-ETO, AML1-ETO9a, MLL-ENL, and MLL-AF9.
The researchers also transduced cells from Booreana mice and wild-type mice with either AML1-ETO9a or MLL-AF9 retroviruses and transplanted the cells into irradiated mice. The cells from wild-type mice generated leukemia in the recipients, but the Booreana cells did not.
Lastly, the team performed gene expression analyses to gain more insight into the Myb-p300 relationship. They found that several genes already implicated in myeloid leukemogenesis and hematopoietic stem cell function are regulated in an Myb-p300-dependent manner.
The researchers therefore concluded that the Myb-p300 interaction is important to myeloid leukemogenesis. And disrupting this interaction could prove useful in the fight against AML.
Dr Gonda pointed out, however, that the Myb protein is produced by the MYB oncogene. And although this oncogene is required for the continued growth of leukemia cells, it is also essential for normal blood cell formation.
“[S]o we need an approach for targeting it that won’t completely disrupt normal blood cell production,” he said. “Our research shows that normal blood cells can continue to form even when the Myb-p300 interaction is unable to occur, suggesting that a drug that blocks the interaction could be safe for use in patients.”
Dr Gonda and his colleagues are also planning to examine the possibility of targeting genes and proteins that work downstream of MYB.
Drug confers benefits for subset of AML patients
Credit: Rhoda Baer
A drug that combines 2 chemotherapy agents into 1 can be more effective than treatment with the individual agents in combination, results of a phase 2 study suggest.
The drug, CPX-351, is a fixed-ratio combination of cytarabine and daunorubicin inside a lipid vesicle.
In older patients with acute myeloid leukemia (AML), CPX-351 elicited a higher response rate than combination treatment with cytarabine and daunorubicin, although the difference was not significant.
Likewise, there were no significant differences in event-free survival (EFS) or overall survival (OS) between the 2 treatment groups.
However, CPX-351 conferred a significant response benefit among patients with poor cytogenetics and a significant survival benefit in patients with secondary AML (sAML).
Jeffrey Lancet, MD, of the Moffitt Cancer Center in Tampa, Florida, and his colleagues reported these results in Blood. The study was funded by Celator Pharmaceuticals, the company developing CPX-351.
Treatment details
The researchers analyzed 126 newly diagnosed AML patients who were 60 to 75 years of age.
Patients were randomized to receive CPX-351 (n=85) or “control” treatment consisting of cytarabine and daunorubicin (n=41). The 2 treatment groups were well-balanced for disease and patient characteristics at baseline.
As induction, patients in the CPX-351 arm received a 90-minute infusion of the drug at 100 units/m2 on days 1, 3, and 5 (delivering 100 mg/m2 cytarabine and 44 mg/m2 daunorubicin with each dose). Second induction and consolidation courses were given at 100 units/m2 on days 1 and 3.
Patients in the control arm received induction therapy consisting of cytarabine at 100 mg/m2/day by 7-day continuous infusion and daunorubicin at 60 mg/m2/day on days 1, 2, and 3. Daunorubicin could be reduced to 45 mg/m2/day at the investigator’s discretion for patients with advanced age, poor performance status, or reduced liver/kidney function.
The choice of consolidation therapy was at the investigator’s discretion as well. The recommended regimens included cytarabine at 100 to 200 mg/m2 for 5 to 7 days, with or without daunorubicin or intermediate-dose cytarabine (1.0 to 1.5 g/m2/dose).
Response and survival
The response rate was higher in the CPX-351 arm than in the control arm—66.7% and 51.2%, respectively (P=0.07), which met the predefined criterion for success (P<0.1). Response was defined as a complete response (CR) or a complete response with incomplete blood count recovery (CRi).
CRs occurred in 48.8% of patients in both arms. But CRis favored the CPX-351 arm over the control arm—17.9% and 2.4%, respectively.
Likewise, response rates favoring CPX-351 occurred in patients with adverse cytogenetics and sAML.
Among patients with adverse cytogenetics, the response rate was 77.3% in the CPX-351 arm and 38.5% in the control arm (P=0.03). And among patients with sAML, the response rate was 57.6% in the CPX-351 arm and 31.6% in the control arm (P=0.06).
The median OS was 14.7 months in the CPX-351 arm and 12.9 months in the control arm. The median EFS was 6.5 months and 2.0 months, respectively. These differences were not statistically significant.
However, sAML patients treated with CPX-351 had significantly better OS than sAML patients in the control arm. The median OS was 12.1 months and 6.1 months, respectively (P=0.01). And the median EFS was 4.5 months and 1.3 months, respectively (P=0.08).
Safety results
By day 60, 4.7% of patients in the CPX-351 arm and 14.6% of patients in the control arm had died. All of these deaths occurred in high-risk patients, particularly those with sAML.
Two patients died of intracranial hemorrhage during CPX-351 consolidation. One of these deaths was associated with head trauma and relapsed AML, and the other was from chemotherapy-induced thrombocytopenia.
For many of the most common adverse events, there were minimal differences between the treatment arms. These events included febrile neutropenia, infection, rash, diarrhea, nausea, edema, and constipation.
Patients in the CPX-351 arm had a higher incidence of grade 3-4 infection than controls—70.6% and 43.9%, respectively—but not infection-related deaths—3.5% and 7.3%, respectively.
The median time to neutrophil recovery (to ≥ 1000/μL) was longer in the CPX-351 arm than the control arm—36 days and 32 days, respectively. The same was true for platelet recovery (to ≥ 100,000/μL)—37 days and 28 days, respectively.
Researchers are now conducting a phase 3 trial of CPX-351, which is open and recruiting patients.
Credit: Rhoda Baer
A drug that combines 2 chemotherapy agents into 1 can be more effective than treatment with the individual agents in combination, results of a phase 2 study suggest.
The drug, CPX-351, is a fixed-ratio combination of cytarabine and daunorubicin inside a lipid vesicle.
In older patients with acute myeloid leukemia (AML), CPX-351 elicited a higher response rate than combination treatment with cytarabine and daunorubicin, although the difference was not significant.
Likewise, there were no significant differences in event-free survival (EFS) or overall survival (OS) between the 2 treatment groups.
However, CPX-351 conferred a significant response benefit among patients with poor cytogenetics and a significant survival benefit in patients with secondary AML (sAML).
Jeffrey Lancet, MD, of the Moffitt Cancer Center in Tampa, Florida, and his colleagues reported these results in Blood. The study was funded by Celator Pharmaceuticals, the company developing CPX-351.
Treatment details
The researchers analyzed 126 newly diagnosed AML patients who were 60 to 75 years of age.
Patients were randomized to receive CPX-351 (n=85) or “control” treatment consisting of cytarabine and daunorubicin (n=41). The 2 treatment groups were well-balanced for disease and patient characteristics at baseline.
As induction, patients in the CPX-351 arm received a 90-minute infusion of the drug at 100 units/m2 on days 1, 3, and 5 (delivering 100 mg/m2 cytarabine and 44 mg/m2 daunorubicin with each dose). Second induction and consolidation courses were given at 100 units/m2 on days 1 and 3.
Patients in the control arm received induction therapy consisting of cytarabine at 100 mg/m2/day by 7-day continuous infusion and daunorubicin at 60 mg/m2/day on days 1, 2, and 3. Daunorubicin could be reduced to 45 mg/m2/day at the investigator’s discretion for patients with advanced age, poor performance status, or reduced liver/kidney function.
The choice of consolidation therapy was at the investigator’s discretion as well. The recommended regimens included cytarabine at 100 to 200 mg/m2 for 5 to 7 days, with or without daunorubicin or intermediate-dose cytarabine (1.0 to 1.5 g/m2/dose).
Response and survival
The response rate was higher in the CPX-351 arm than in the control arm—66.7% and 51.2%, respectively (P=0.07), which met the predefined criterion for success (P<0.1). Response was defined as a complete response (CR) or a complete response with incomplete blood count recovery (CRi).
CRs occurred in 48.8% of patients in both arms. But CRis favored the CPX-351 arm over the control arm—17.9% and 2.4%, respectively.
Likewise, response rates favoring CPX-351 occurred in patients with adverse cytogenetics and sAML.
Among patients with adverse cytogenetics, the response rate was 77.3% in the CPX-351 arm and 38.5% in the control arm (P=0.03). And among patients with sAML, the response rate was 57.6% in the CPX-351 arm and 31.6% in the control arm (P=0.06).
The median OS was 14.7 months in the CPX-351 arm and 12.9 months in the control arm. The median EFS was 6.5 months and 2.0 months, respectively. These differences were not statistically significant.
However, sAML patients treated with CPX-351 had significantly better OS than sAML patients in the control arm. The median OS was 12.1 months and 6.1 months, respectively (P=0.01). And the median EFS was 4.5 months and 1.3 months, respectively (P=0.08).
Safety results
By day 60, 4.7% of patients in the CPX-351 arm and 14.6% of patients in the control arm had died. All of these deaths occurred in high-risk patients, particularly those with sAML.
Two patients died of intracranial hemorrhage during CPX-351 consolidation. One of these deaths was associated with head trauma and relapsed AML, and the other was from chemotherapy-induced thrombocytopenia.
For many of the most common adverse events, there were minimal differences between the treatment arms. These events included febrile neutropenia, infection, rash, diarrhea, nausea, edema, and constipation.
Patients in the CPX-351 arm had a higher incidence of grade 3-4 infection than controls—70.6% and 43.9%, respectively—but not infection-related deaths—3.5% and 7.3%, respectively.
The median time to neutrophil recovery (to ≥ 1000/μL) was longer in the CPX-351 arm than the control arm—36 days and 32 days, respectively. The same was true for platelet recovery (to ≥ 100,000/μL)—37 days and 28 days, respectively.
Researchers are now conducting a phase 3 trial of CPX-351, which is open and recruiting patients.
Credit: Rhoda Baer
A drug that combines 2 chemotherapy agents into 1 can be more effective than treatment with the individual agents in combination, results of a phase 2 study suggest.
The drug, CPX-351, is a fixed-ratio combination of cytarabine and daunorubicin inside a lipid vesicle.
In older patients with acute myeloid leukemia (AML), CPX-351 elicited a higher response rate than combination treatment with cytarabine and daunorubicin, although the difference was not significant.
Likewise, there were no significant differences in event-free survival (EFS) or overall survival (OS) between the 2 treatment groups.
However, CPX-351 conferred a significant response benefit among patients with poor cytogenetics and a significant survival benefit in patients with secondary AML (sAML).
Jeffrey Lancet, MD, of the Moffitt Cancer Center in Tampa, Florida, and his colleagues reported these results in Blood. The study was funded by Celator Pharmaceuticals, the company developing CPX-351.
Treatment details
The researchers analyzed 126 newly diagnosed AML patients who were 60 to 75 years of age.
Patients were randomized to receive CPX-351 (n=85) or “control” treatment consisting of cytarabine and daunorubicin (n=41). The 2 treatment groups were well-balanced for disease and patient characteristics at baseline.
As induction, patients in the CPX-351 arm received a 90-minute infusion of the drug at 100 units/m2 on days 1, 3, and 5 (delivering 100 mg/m2 cytarabine and 44 mg/m2 daunorubicin with each dose). Second induction and consolidation courses were given at 100 units/m2 on days 1 and 3.
Patients in the control arm received induction therapy consisting of cytarabine at 100 mg/m2/day by 7-day continuous infusion and daunorubicin at 60 mg/m2/day on days 1, 2, and 3. Daunorubicin could be reduced to 45 mg/m2/day at the investigator’s discretion for patients with advanced age, poor performance status, or reduced liver/kidney function.
The choice of consolidation therapy was at the investigator’s discretion as well. The recommended regimens included cytarabine at 100 to 200 mg/m2 for 5 to 7 days, with or without daunorubicin or intermediate-dose cytarabine (1.0 to 1.5 g/m2/dose).
Response and survival
The response rate was higher in the CPX-351 arm than in the control arm—66.7% and 51.2%, respectively (P=0.07), which met the predefined criterion for success (P<0.1). Response was defined as a complete response (CR) or a complete response with incomplete blood count recovery (CRi).
CRs occurred in 48.8% of patients in both arms. But CRis favored the CPX-351 arm over the control arm—17.9% and 2.4%, respectively.
Likewise, response rates favoring CPX-351 occurred in patients with adverse cytogenetics and sAML.
Among patients with adverse cytogenetics, the response rate was 77.3% in the CPX-351 arm and 38.5% in the control arm (P=0.03). And among patients with sAML, the response rate was 57.6% in the CPX-351 arm and 31.6% in the control arm (P=0.06).
The median OS was 14.7 months in the CPX-351 arm and 12.9 months in the control arm. The median EFS was 6.5 months and 2.0 months, respectively. These differences were not statistically significant.
However, sAML patients treated with CPX-351 had significantly better OS than sAML patients in the control arm. The median OS was 12.1 months and 6.1 months, respectively (P=0.01). And the median EFS was 4.5 months and 1.3 months, respectively (P=0.08).
Safety results
By day 60, 4.7% of patients in the CPX-351 arm and 14.6% of patients in the control arm had died. All of these deaths occurred in high-risk patients, particularly those with sAML.
Two patients died of intracranial hemorrhage during CPX-351 consolidation. One of these deaths was associated with head trauma and relapsed AML, and the other was from chemotherapy-induced thrombocytopenia.
For many of the most common adverse events, there were minimal differences between the treatment arms. These events included febrile neutropenia, infection, rash, diarrhea, nausea, edema, and constipation.
Patients in the CPX-351 arm had a higher incidence of grade 3-4 infection than controls—70.6% and 43.9%, respectively—but not infection-related deaths—3.5% and 7.3%, respectively.
The median time to neutrophil recovery (to ≥ 1000/μL) was longer in the CPX-351 arm than the control arm—36 days and 32 days, respectively. The same was true for platelet recovery (to ≥ 100,000/μL)—37 days and 28 days, respectively.
Researchers are now conducting a phase 3 trial of CPX-351, which is open and recruiting patients.
Leukemic breast tumors may cause resistance in AML, ALL
SAN DIEGO—One woman’s curiosity and self-described “aggressive” approach to research have led to some unexpected discoveries about acute leukemias.
Isabel Cunningham, MD, of Columbia University in New York, has found evidence to suggest that treatment resistance in leukemia patients may sometimes result from an interaction between leukemic cells and the breast.
She discovered that leukemic cells in extramedullary niches can adopt a tumor phenotype similar to breast cancer.
And many genes are similarly upregulated in leukemic and epithelial breast tumors.
Her research indicates that a new approach to resistant leukemias that incorporates the principles of solid-tumor treatment—scans to identify any tumors and surgery to remove them—could decrease marrow relapse and death.
Dr Cunningham and her colleagues presented these findings in a poster at the AACR Annual Meeting 2014 (abstract 3996*).
“Chemotherapy resistance is our main problem in treating leukemia,” Dr Cunningham said. “It’s been known for a long time that, occasionally, leukemia forms tumors in an organ, but there’s never been a unified approach to treatment, except for leukemia that occurs in the testis and the meninges.”
Dr Cunningham had encountered many patients with resistant leukemia throughout her career, but her research actually began with a patient she had never met. A case study of a leukemia patient with a breast tumor sparked Dr Cunningham’s interest, and she emailed the study’s author to find out what ultimately became of the patient.
The response she received peaked her curiosity further. So she began seeking more of these cases, contacting authors, and collecting information on this phenomenon.
“I took this on as sort of a hobby,” Dr Cunningham said. “I never had any idea where this was going to lead.”
Eventually, she had amassed information on 235 cases—163 patients with acute myeloid leukemia (AML) and 72 with acute lymphoblastic leukemia (ALL)—who ranged from 1 year to 75 years of age. And an analysis of these cases led to some surprising discoveries.
Clinical findings
Dr Cunningham found these leukemic breast tumors can occur before, during, or after marrow leukemia. And, clinically, they resemble breast cancer. Most tumors were palpable, and some were detected only on routine mammograms.
There were single or multiple nodules that may have involved the entire breast. Sixty percent of cases were unilateral on presentation, but, often, the other breast became involved. Seventy percent of cases exhibited axillary lymphadenopathy that was ipsilateral.
Most tumors grew rapidly, to as large as 12 cm. The tumor behavior was similar in AML and ALL. And the tumors had a metastatic pattern similar to lobular breast cancer—spreading to the contralateral breast, the abdomen or pelvis, the meninges, and culminating in death.
However, some patients did survive. Four percent of patients who were treated only with chemotherapy were alive at 4 years. Twenty-five percent of patients had their tumors excised prior to chemotherapy and were alive anywhere from 3 years to more than 26 years after treatment.
Histology and gene expression
To build upon these findings, Dr Cunningham set her sights on patient samples. She was able to obtain paraffin blocks of leukemic breast tumors from 25 patients and perform immunohistochemical staining.
“It became clear that the leukemic tumors—which are marked by leukemic markers and not breast cancer markers—look, histologically, like breast cancer, specifically, lobular breast cancer,” Dr Cunningham said. “An additional pathologic finding was a specific type of desmoplastic fibrosis seen in all 25 contributed biopsies.”
Dr Cunningham also performed gene expression studies on 3 of the tumors (2 ALL and 1 AML), which were collected 8 months to 22 months after diagnosis, while marrows were in remission. The analyses revealed that a number of genes are significantly upregulated in both leukemic breast tumors and breast cancer.
These include genes involved in adhesion and interactions with the extracellular matrix (ADAM8, COMP, and CDH22), genes involved in the ubiquitin-proteasome pathway (UBE2S, USP32, MDM2, and UBE2C), genes encoding for kinases (MAP4K1, PIM1, and NEK2), and genes involved in RAS signaling (RANBP1 and RAB10).
Conclusions and next steps
“It seems that there’s some kind of crosstalk between the organ microenvironment and leukemic cells that make the leukemic cells have the phenotype of breast cancer,” Dr Cunningham said. “And it may well be that relapse sometimes results from the presence of an undiagnosed collection of these cells.”
Therefore, Dr Cunningham suggests performing scans in treatment-resistant leukemia patients. If a patient relapses, and particularly if lactic dehydrogenase levels are increased, a scan might be in order.
“If we can recognize these tumors and cut them out, the patient could be cured, because we’re successful at treating the bone marrow,” Dr Cunningham said. “We’ve had very good bone marrow drugs for 50 years.”
For her part, Dr Cunningham is delving further into this phenomenon. She is now conducting gene expression studies on the rest of the 25 leukemic breast tumor samples and comparing these tumors to breast cancer to identify the most significant dysregulated genes in both entities. The long-term goal is to find a way to predict which patients will develop leukemic breast tumors.
*Information in the abstract differs from that presented at the meeting.
SAN DIEGO—One woman’s curiosity and self-described “aggressive” approach to research have led to some unexpected discoveries about acute leukemias.
Isabel Cunningham, MD, of Columbia University in New York, has found evidence to suggest that treatment resistance in leukemia patients may sometimes result from an interaction between leukemic cells and the breast.
She discovered that leukemic cells in extramedullary niches can adopt a tumor phenotype similar to breast cancer.
And many genes are similarly upregulated in leukemic and epithelial breast tumors.
Her research indicates that a new approach to resistant leukemias that incorporates the principles of solid-tumor treatment—scans to identify any tumors and surgery to remove them—could decrease marrow relapse and death.
Dr Cunningham and her colleagues presented these findings in a poster at the AACR Annual Meeting 2014 (abstract 3996*).
“Chemotherapy resistance is our main problem in treating leukemia,” Dr Cunningham said. “It’s been known for a long time that, occasionally, leukemia forms tumors in an organ, but there’s never been a unified approach to treatment, except for leukemia that occurs in the testis and the meninges.”
Dr Cunningham had encountered many patients with resistant leukemia throughout her career, but her research actually began with a patient she had never met. A case study of a leukemia patient with a breast tumor sparked Dr Cunningham’s interest, and she emailed the study’s author to find out what ultimately became of the patient.
The response she received peaked her curiosity further. So she began seeking more of these cases, contacting authors, and collecting information on this phenomenon.
“I took this on as sort of a hobby,” Dr Cunningham said. “I never had any idea where this was going to lead.”
Eventually, she had amassed information on 235 cases—163 patients with acute myeloid leukemia (AML) and 72 with acute lymphoblastic leukemia (ALL)—who ranged from 1 year to 75 years of age. And an analysis of these cases led to some surprising discoveries.
Clinical findings
Dr Cunningham found these leukemic breast tumors can occur before, during, or after marrow leukemia. And, clinically, they resemble breast cancer. Most tumors were palpable, and some were detected only on routine mammograms.
There were single or multiple nodules that may have involved the entire breast. Sixty percent of cases were unilateral on presentation, but, often, the other breast became involved. Seventy percent of cases exhibited axillary lymphadenopathy that was ipsilateral.
Most tumors grew rapidly, to as large as 12 cm. The tumor behavior was similar in AML and ALL. And the tumors had a metastatic pattern similar to lobular breast cancer—spreading to the contralateral breast, the abdomen or pelvis, the meninges, and culminating in death.
However, some patients did survive. Four percent of patients who were treated only with chemotherapy were alive at 4 years. Twenty-five percent of patients had their tumors excised prior to chemotherapy and were alive anywhere from 3 years to more than 26 years after treatment.
Histology and gene expression
To build upon these findings, Dr Cunningham set her sights on patient samples. She was able to obtain paraffin blocks of leukemic breast tumors from 25 patients and perform immunohistochemical staining.
“It became clear that the leukemic tumors—which are marked by leukemic markers and not breast cancer markers—look, histologically, like breast cancer, specifically, lobular breast cancer,” Dr Cunningham said. “An additional pathologic finding was a specific type of desmoplastic fibrosis seen in all 25 contributed biopsies.”
Dr Cunningham also performed gene expression studies on 3 of the tumors (2 ALL and 1 AML), which were collected 8 months to 22 months after diagnosis, while marrows were in remission. The analyses revealed that a number of genes are significantly upregulated in both leukemic breast tumors and breast cancer.
These include genes involved in adhesion and interactions with the extracellular matrix (ADAM8, COMP, and CDH22), genes involved in the ubiquitin-proteasome pathway (UBE2S, USP32, MDM2, and UBE2C), genes encoding for kinases (MAP4K1, PIM1, and NEK2), and genes involved in RAS signaling (RANBP1 and RAB10).
Conclusions and next steps
“It seems that there’s some kind of crosstalk between the organ microenvironment and leukemic cells that make the leukemic cells have the phenotype of breast cancer,” Dr Cunningham said. “And it may well be that relapse sometimes results from the presence of an undiagnosed collection of these cells.”
Therefore, Dr Cunningham suggests performing scans in treatment-resistant leukemia patients. If a patient relapses, and particularly if lactic dehydrogenase levels are increased, a scan might be in order.
“If we can recognize these tumors and cut them out, the patient could be cured, because we’re successful at treating the bone marrow,” Dr Cunningham said. “We’ve had very good bone marrow drugs for 50 years.”
For her part, Dr Cunningham is delving further into this phenomenon. She is now conducting gene expression studies on the rest of the 25 leukemic breast tumor samples and comparing these tumors to breast cancer to identify the most significant dysregulated genes in both entities. The long-term goal is to find a way to predict which patients will develop leukemic breast tumors.
*Information in the abstract differs from that presented at the meeting.
SAN DIEGO—One woman’s curiosity and self-described “aggressive” approach to research have led to some unexpected discoveries about acute leukemias.
Isabel Cunningham, MD, of Columbia University in New York, has found evidence to suggest that treatment resistance in leukemia patients may sometimes result from an interaction between leukemic cells and the breast.
She discovered that leukemic cells in extramedullary niches can adopt a tumor phenotype similar to breast cancer.
And many genes are similarly upregulated in leukemic and epithelial breast tumors.
Her research indicates that a new approach to resistant leukemias that incorporates the principles of solid-tumor treatment—scans to identify any tumors and surgery to remove them—could decrease marrow relapse and death.
Dr Cunningham and her colleagues presented these findings in a poster at the AACR Annual Meeting 2014 (abstract 3996*).
“Chemotherapy resistance is our main problem in treating leukemia,” Dr Cunningham said. “It’s been known for a long time that, occasionally, leukemia forms tumors in an organ, but there’s never been a unified approach to treatment, except for leukemia that occurs in the testis and the meninges.”
Dr Cunningham had encountered many patients with resistant leukemia throughout her career, but her research actually began with a patient she had never met. A case study of a leukemia patient with a breast tumor sparked Dr Cunningham’s interest, and she emailed the study’s author to find out what ultimately became of the patient.
The response she received peaked her curiosity further. So she began seeking more of these cases, contacting authors, and collecting information on this phenomenon.
“I took this on as sort of a hobby,” Dr Cunningham said. “I never had any idea where this was going to lead.”
Eventually, she had amassed information on 235 cases—163 patients with acute myeloid leukemia (AML) and 72 with acute lymphoblastic leukemia (ALL)—who ranged from 1 year to 75 years of age. And an analysis of these cases led to some surprising discoveries.
Clinical findings
Dr Cunningham found these leukemic breast tumors can occur before, during, or after marrow leukemia. And, clinically, they resemble breast cancer. Most tumors were palpable, and some were detected only on routine mammograms.
There were single or multiple nodules that may have involved the entire breast. Sixty percent of cases were unilateral on presentation, but, often, the other breast became involved. Seventy percent of cases exhibited axillary lymphadenopathy that was ipsilateral.
Most tumors grew rapidly, to as large as 12 cm. The tumor behavior was similar in AML and ALL. And the tumors had a metastatic pattern similar to lobular breast cancer—spreading to the contralateral breast, the abdomen or pelvis, the meninges, and culminating in death.
However, some patients did survive. Four percent of patients who were treated only with chemotherapy were alive at 4 years. Twenty-five percent of patients had their tumors excised prior to chemotherapy and were alive anywhere from 3 years to more than 26 years after treatment.
Histology and gene expression
To build upon these findings, Dr Cunningham set her sights on patient samples. She was able to obtain paraffin blocks of leukemic breast tumors from 25 patients and perform immunohistochemical staining.
“It became clear that the leukemic tumors—which are marked by leukemic markers and not breast cancer markers—look, histologically, like breast cancer, specifically, lobular breast cancer,” Dr Cunningham said. “An additional pathologic finding was a specific type of desmoplastic fibrosis seen in all 25 contributed biopsies.”
Dr Cunningham also performed gene expression studies on 3 of the tumors (2 ALL and 1 AML), which were collected 8 months to 22 months after diagnosis, while marrows were in remission. The analyses revealed that a number of genes are significantly upregulated in both leukemic breast tumors and breast cancer.
These include genes involved in adhesion and interactions with the extracellular matrix (ADAM8, COMP, and CDH22), genes involved in the ubiquitin-proteasome pathway (UBE2S, USP32, MDM2, and UBE2C), genes encoding for kinases (MAP4K1, PIM1, and NEK2), and genes involved in RAS signaling (RANBP1 and RAB10).
Conclusions and next steps
“It seems that there’s some kind of crosstalk between the organ microenvironment and leukemic cells that make the leukemic cells have the phenotype of breast cancer,” Dr Cunningham said. “And it may well be that relapse sometimes results from the presence of an undiagnosed collection of these cells.”
Therefore, Dr Cunningham suggests performing scans in treatment-resistant leukemia patients. If a patient relapses, and particularly if lactic dehydrogenase levels are increased, a scan might be in order.
“If we can recognize these tumors and cut them out, the patient could be cured, because we’re successful at treating the bone marrow,” Dr Cunningham said. “We’ve had very good bone marrow drugs for 50 years.”
For her part, Dr Cunningham is delving further into this phenomenon. She is now conducting gene expression studies on the rest of the 25 leukemic breast tumor samples and comparing these tumors to breast cancer to identify the most significant dysregulated genes in both entities. The long-term goal is to find a way to predict which patients will develop leukemic breast tumors.
*Information in the abstract differs from that presented at the meeting.
Embedded miRNA, not its host, drives AML, group says
Credit: Lance Liotta
A small gene embedded in a larger gene appears to be the driving force behind acute myeloid leukemia (AML) development, according to research published in Science Signaling.
The smaller gene, microRNA-3151 (miR-3151), is embedded in intron 1 of the larger gene, BAALC.
As both genes have been associated with poor prognosis in AML, researchers wanted to determine the degree to which each of the genes contributes to AML.
“We discovered that the smaller microRNA gene, and not the larger host gene, is the major oncogenic driver of the 2 molecules in AML,” said principal investigator Albert de la Chapelle, MD, PhD, of The Ohio State University Comprehensive Cancer Center (OSUCCC) in Columbus.
“When both genes are highly expressed, it means a bad prognosis for patients, but our experiments indicate that it is high expression of miR-3151 that really matters. Overexpression of BAALC alone had only limited cancer-causing activity.”
Dr de la Chapelle and his colleagues used AML cells derived from patients, AML cell lines, and an animal model of the disease to investigate the role of miR-3151 and BAALC in older patients with cytogenetically normal AML.
The team found that miR-3151 promotes leukemia development by targeting the tumor suppressor TP53 and 7 other genes in the TP53 pathway.
“When miR-3151 blocks TP53 in the tumor cells, it enables the cells to survive, divide, and grow faster,” said study author Clara D. Bloomfield, MD, of OSUCCC.
Experiments also showed that overexpressing miR-3151 promotes AML cell growth. BAALC overexpression enhances that effect, but blocking miR-3151 or overexpressing TP53 reverses it.
In mice, miR-3151 alone and in combination with BAALC promoted leukemia development.
Finally, the researchers discovered that miR-3151 overexpression can be inhibited by the proteasome inhibitor bortezomib, which suggests a possible therapy for miR-3151 overexpression.
“About one-third of the several hundred known human microRNAs are encoded in host genes,” said study author Ann-Kathrin Eisfeld, MD, of OSUCCC.
“We know very little about how microRNAs located within introns are regulated and how they interact with their host genes. These findings provide an important example of that interaction.”
Credit: Lance Liotta
A small gene embedded in a larger gene appears to be the driving force behind acute myeloid leukemia (AML) development, according to research published in Science Signaling.
The smaller gene, microRNA-3151 (miR-3151), is embedded in intron 1 of the larger gene, BAALC.
As both genes have been associated with poor prognosis in AML, researchers wanted to determine the degree to which each of the genes contributes to AML.
“We discovered that the smaller microRNA gene, and not the larger host gene, is the major oncogenic driver of the 2 molecules in AML,” said principal investigator Albert de la Chapelle, MD, PhD, of The Ohio State University Comprehensive Cancer Center (OSUCCC) in Columbus.
“When both genes are highly expressed, it means a bad prognosis for patients, but our experiments indicate that it is high expression of miR-3151 that really matters. Overexpression of BAALC alone had only limited cancer-causing activity.”
Dr de la Chapelle and his colleagues used AML cells derived from patients, AML cell lines, and an animal model of the disease to investigate the role of miR-3151 and BAALC in older patients with cytogenetically normal AML.
The team found that miR-3151 promotes leukemia development by targeting the tumor suppressor TP53 and 7 other genes in the TP53 pathway.
“When miR-3151 blocks TP53 in the tumor cells, it enables the cells to survive, divide, and grow faster,” said study author Clara D. Bloomfield, MD, of OSUCCC.
Experiments also showed that overexpressing miR-3151 promotes AML cell growth. BAALC overexpression enhances that effect, but blocking miR-3151 or overexpressing TP53 reverses it.
In mice, miR-3151 alone and in combination with BAALC promoted leukemia development.
Finally, the researchers discovered that miR-3151 overexpression can be inhibited by the proteasome inhibitor bortezomib, which suggests a possible therapy for miR-3151 overexpression.
“About one-third of the several hundred known human microRNAs are encoded in host genes,” said study author Ann-Kathrin Eisfeld, MD, of OSUCCC.
“We know very little about how microRNAs located within introns are regulated and how they interact with their host genes. These findings provide an important example of that interaction.”
Credit: Lance Liotta
A small gene embedded in a larger gene appears to be the driving force behind acute myeloid leukemia (AML) development, according to research published in Science Signaling.
The smaller gene, microRNA-3151 (miR-3151), is embedded in intron 1 of the larger gene, BAALC.
As both genes have been associated with poor prognosis in AML, researchers wanted to determine the degree to which each of the genes contributes to AML.
“We discovered that the smaller microRNA gene, and not the larger host gene, is the major oncogenic driver of the 2 molecules in AML,” said principal investigator Albert de la Chapelle, MD, PhD, of The Ohio State University Comprehensive Cancer Center (OSUCCC) in Columbus.
“When both genes are highly expressed, it means a bad prognosis for patients, but our experiments indicate that it is high expression of miR-3151 that really matters. Overexpression of BAALC alone had only limited cancer-causing activity.”
Dr de la Chapelle and his colleagues used AML cells derived from patients, AML cell lines, and an animal model of the disease to investigate the role of miR-3151 and BAALC in older patients with cytogenetically normal AML.
The team found that miR-3151 promotes leukemia development by targeting the tumor suppressor TP53 and 7 other genes in the TP53 pathway.
“When miR-3151 blocks TP53 in the tumor cells, it enables the cells to survive, divide, and grow faster,” said study author Clara D. Bloomfield, MD, of OSUCCC.
Experiments also showed that overexpressing miR-3151 promotes AML cell growth. BAALC overexpression enhances that effect, but blocking miR-3151 or overexpressing TP53 reverses it.
In mice, miR-3151 alone and in combination with BAALC promoted leukemia development.
Finally, the researchers discovered that miR-3151 overexpression can be inhibited by the proteasome inhibitor bortezomib, which suggests a possible therapy for miR-3151 overexpression.
“About one-third of the several hundred known human microRNAs are encoded in host genes,” said study author Ann-Kathrin Eisfeld, MD, of OSUCCC.
“We know very little about how microRNAs located within introns are regulated and how they interact with their host genes. These findings provide an important example of that interaction.”
Team identifies potential treatment for FLT3-ITD AML
Credit: Eric Smith
Researchers have presented evidence to support the use of a BET protein antagonist in FLT3-ITD-mutated acute myeloid leukemia (AML).
The group’s experiments showed the antagonist, JQ1, was active against FLT3-ITD-expressing AML cells in vitro and in vivo.
The agent also demonstrated synergy with the tyrosine kinase inhibitor (TKI) AC220 and the histone deacetylase (HDAC) inhibitor panobinostat.
In fact, JQ1 and panobinostat in combination induced apoptosis in a TKI-resistant cell line.
Melissa Rodriguez, MD, PhD, of the Houston Methodist Research Institute in Texas, and her colleagues presented these findings at the AACR Annual Meeting 2014 as abstract 1721.
The BET protein family members, including BRD4, bind to acetylated lysines on histone proteins, help assemble transcriptional regulators at the target gene promoters and enhancers, and regulate the expression of oncogenes such as MYC and BCL-2.
JQ1 interferes with BRD4 binding to acetylated lysines on histone proteins, resulting in the displacement of the BET proteins. This, in turn, disrupts transcription initiation and elongation factors situated on the chromatin, thereby inhibiting expressions of c-MYC and BCL-2 and their target genes. And this leads to growth arrest and the induction of apoptosis in AML cells.
Dr Rodriguez and her colleagues found that JQ1 alone induced apoptosis in cultured mouse lymphoid cells such as Ba/F3/FLT3-ITD but also Ba/F3/FLT3-ITD that expressed the FLT3-TKI-resistant mutations F691L and D835V.
JQ1 also attenuated the expression of c-MYC, BCL2, and CDK6 oncogenes; induced the expression of p21, p27, and BIM; and cleaved PARP levels.
Furthermore, JQ1 dose-dependently induced apoptosis in MOLM13 and MV4-11 cell lines, as well as in primary AML cells that all expressed FLT3-ITD but had not become resistant to TKIs.
In SCID mice that received non-TKI-treated MOLM13 xenografts, JQ1 alone significantly improved survival compared to vehicle controls. And the researchers observed no toxicity in the treated mice.
JQ1 plus AC220 or panobinostat synergistically induced apoptosis in MV4-11 cells, MOLM13 cells, and primary AML cells expressing FLT3-ITD.
In testing MOLM13/TKIR cells, which had a greater than 50-fold resistance to AC220 over the other cell lines tested, the researchers discovered these cells express higher levels of BRD4, c-MYC, and class I HDACs. They were also significantly more sensitive to JQ1-induced apoptosis.
In this AC220-resistant cell line, JQ1 and panobinostat synergistically induced apoptosis. But, as expected, the same effect did not occur when JQ1 was administered with AC220.
The synergistic apoptotic response of panobinostat and JQ1 was associated with the down-regulation of c-MYC and demonstrated JQ1’s ability to overcome AC220-induced TKI resistance in FLT3-ITD-expressing cells.
The researchers said these findings support future in vivo testing of BRD4 antagonists such as JQ1 in combination with TKIs such as AC220 or HDAC inhibitors such as panobinostat against FLT3-TKI-sensitive cell lines. The research also supports using BRD4 antagonists in combination with panobinostat against TKI-resistant, FLT3-ITD-mutated AML.
Credit: Eric Smith
Researchers have presented evidence to support the use of a BET protein antagonist in FLT3-ITD-mutated acute myeloid leukemia (AML).
The group’s experiments showed the antagonist, JQ1, was active against FLT3-ITD-expressing AML cells in vitro and in vivo.
The agent also demonstrated synergy with the tyrosine kinase inhibitor (TKI) AC220 and the histone deacetylase (HDAC) inhibitor panobinostat.
In fact, JQ1 and panobinostat in combination induced apoptosis in a TKI-resistant cell line.
Melissa Rodriguez, MD, PhD, of the Houston Methodist Research Institute in Texas, and her colleagues presented these findings at the AACR Annual Meeting 2014 as abstract 1721.
The BET protein family members, including BRD4, bind to acetylated lysines on histone proteins, help assemble transcriptional regulators at the target gene promoters and enhancers, and regulate the expression of oncogenes such as MYC and BCL-2.
JQ1 interferes with BRD4 binding to acetylated lysines on histone proteins, resulting in the displacement of the BET proteins. This, in turn, disrupts transcription initiation and elongation factors situated on the chromatin, thereby inhibiting expressions of c-MYC and BCL-2 and their target genes. And this leads to growth arrest and the induction of apoptosis in AML cells.
Dr Rodriguez and her colleagues found that JQ1 alone induced apoptosis in cultured mouse lymphoid cells such as Ba/F3/FLT3-ITD but also Ba/F3/FLT3-ITD that expressed the FLT3-TKI-resistant mutations F691L and D835V.
JQ1 also attenuated the expression of c-MYC, BCL2, and CDK6 oncogenes; induced the expression of p21, p27, and BIM; and cleaved PARP levels.
Furthermore, JQ1 dose-dependently induced apoptosis in MOLM13 and MV4-11 cell lines, as well as in primary AML cells that all expressed FLT3-ITD but had not become resistant to TKIs.
In SCID mice that received non-TKI-treated MOLM13 xenografts, JQ1 alone significantly improved survival compared to vehicle controls. And the researchers observed no toxicity in the treated mice.
JQ1 plus AC220 or panobinostat synergistically induced apoptosis in MV4-11 cells, MOLM13 cells, and primary AML cells expressing FLT3-ITD.
In testing MOLM13/TKIR cells, which had a greater than 50-fold resistance to AC220 over the other cell lines tested, the researchers discovered these cells express higher levels of BRD4, c-MYC, and class I HDACs. They were also significantly more sensitive to JQ1-induced apoptosis.
In this AC220-resistant cell line, JQ1 and panobinostat synergistically induced apoptosis. But, as expected, the same effect did not occur when JQ1 was administered with AC220.
The synergistic apoptotic response of panobinostat and JQ1 was associated with the down-regulation of c-MYC and demonstrated JQ1’s ability to overcome AC220-induced TKI resistance in FLT3-ITD-expressing cells.
The researchers said these findings support future in vivo testing of BRD4 antagonists such as JQ1 in combination with TKIs such as AC220 or HDAC inhibitors such as panobinostat against FLT3-TKI-sensitive cell lines. The research also supports using BRD4 antagonists in combination with panobinostat against TKI-resistant, FLT3-ITD-mutated AML.
Credit: Eric Smith
Researchers have presented evidence to support the use of a BET protein antagonist in FLT3-ITD-mutated acute myeloid leukemia (AML).
The group’s experiments showed the antagonist, JQ1, was active against FLT3-ITD-expressing AML cells in vitro and in vivo.
The agent also demonstrated synergy with the tyrosine kinase inhibitor (TKI) AC220 and the histone deacetylase (HDAC) inhibitor panobinostat.
In fact, JQ1 and panobinostat in combination induced apoptosis in a TKI-resistant cell line.
Melissa Rodriguez, MD, PhD, of the Houston Methodist Research Institute in Texas, and her colleagues presented these findings at the AACR Annual Meeting 2014 as abstract 1721.
The BET protein family members, including BRD4, bind to acetylated lysines on histone proteins, help assemble transcriptional regulators at the target gene promoters and enhancers, and regulate the expression of oncogenes such as MYC and BCL-2.
JQ1 interferes with BRD4 binding to acetylated lysines on histone proteins, resulting in the displacement of the BET proteins. This, in turn, disrupts transcription initiation and elongation factors situated on the chromatin, thereby inhibiting expressions of c-MYC and BCL-2 and their target genes. And this leads to growth arrest and the induction of apoptosis in AML cells.
Dr Rodriguez and her colleagues found that JQ1 alone induced apoptosis in cultured mouse lymphoid cells such as Ba/F3/FLT3-ITD but also Ba/F3/FLT3-ITD that expressed the FLT3-TKI-resistant mutations F691L and D835V.
JQ1 also attenuated the expression of c-MYC, BCL2, and CDK6 oncogenes; induced the expression of p21, p27, and BIM; and cleaved PARP levels.
Furthermore, JQ1 dose-dependently induced apoptosis in MOLM13 and MV4-11 cell lines, as well as in primary AML cells that all expressed FLT3-ITD but had not become resistant to TKIs.
In SCID mice that received non-TKI-treated MOLM13 xenografts, JQ1 alone significantly improved survival compared to vehicle controls. And the researchers observed no toxicity in the treated mice.
JQ1 plus AC220 or panobinostat synergistically induced apoptosis in MV4-11 cells, MOLM13 cells, and primary AML cells expressing FLT3-ITD.
In testing MOLM13/TKIR cells, which had a greater than 50-fold resistance to AC220 over the other cell lines tested, the researchers discovered these cells express higher levels of BRD4, c-MYC, and class I HDACs. They were also significantly more sensitive to JQ1-induced apoptosis.
In this AC220-resistant cell line, JQ1 and panobinostat synergistically induced apoptosis. But, as expected, the same effect did not occur when JQ1 was administered with AC220.
The synergistic apoptotic response of panobinostat and JQ1 was associated with the down-regulation of c-MYC and demonstrated JQ1’s ability to overcome AC220-induced TKI resistance in FLT3-ITD-expressing cells.
The researchers said these findings support future in vivo testing of BRD4 antagonists such as JQ1 in combination with TKIs such as AC220 or HDAC inhibitors such as panobinostat against FLT3-TKI-sensitive cell lines. The research also supports using BRD4 antagonists in combination with panobinostat against TKI-resistant, FLT3-ITD-mutated AML.
Drug gets orphan designation for AML
Credit: NIH
The US Food and Drug Administration and the European Commission have granted volasertib orphan designation for the treatment of acute myeloid leukemia (AML).
Volasertib, an investigational inhibitor of polo-like kinase 1 (Plk1), works by arresting the cell cycle and inducing apoptosis.
The drug is under evaluation as a potential treatment for patients aged 65 or older with previously untreated AML who are ineligible for intensive remission induction therapy.
In both the US and the European Union, orphan designation is awarded for drugs intended to treat rare conditions for which no authorized treatment exists. The designation gives the company developing volasertib, Boehringer Ingelheim, regulatory support and incentives to help the development and authorization process.
Volasertib has already been tested in a phase 1/2 trial of patients with newly diagnosed AML who were considered ineligible for intensive remission induction therapy. The results were presented at the 2012 ASH Annual Meeting as abstract 411.
In this study, volasertib in combination with low-dose cytarabine (LDAC) elicited higher rates of objective response and an improvement in event-free survival, when compared to LDAC alone.
Eighty-seven AML patients were assigned to receive volasertib + LDAC (n=42) or LDAC alone (n=45). Patient characteristics were similar between the 2 groups.
The objective response rate was 31% among patients who received volasertib + LDAC and 11.1% in those who received LDAC alone. The complete response rates were 16.7% and 6.7%, respectively.
The median event-free survival was 169 days for patients who received volasertib + LDAC and 69 days for patients who received LDAC alone.
Grade 3 or higher adverse events were more common in the volasertib + LDAC arm than the LDAC-alone arm—95.2% vs 68.9%.
The most frequent adverse events of any grade occurring in the volasertib + LDAC arm were febrile neutropenia (50%), constipation (45.2%), nausea (40.5%), and anemia (40.5%).
In the LDAC-alone arm, the most common adverse events were nausea (33.3%), anemia (28.9%), pyrexia (28.9%), constipation (26.7%), asthenia (26.7%), and diarrhea (26.7%).
Based on these results, researchers initiated a phase 3 study, called POLO-AML-2, comparing volasertib plus LDAC to LDAC plus placebo in older AML patients.
Credit: NIH
The US Food and Drug Administration and the European Commission have granted volasertib orphan designation for the treatment of acute myeloid leukemia (AML).
Volasertib, an investigational inhibitor of polo-like kinase 1 (Plk1), works by arresting the cell cycle and inducing apoptosis.
The drug is under evaluation as a potential treatment for patients aged 65 or older with previously untreated AML who are ineligible for intensive remission induction therapy.
In both the US and the European Union, orphan designation is awarded for drugs intended to treat rare conditions for which no authorized treatment exists. The designation gives the company developing volasertib, Boehringer Ingelheim, regulatory support and incentives to help the development and authorization process.
Volasertib has already been tested in a phase 1/2 trial of patients with newly diagnosed AML who were considered ineligible for intensive remission induction therapy. The results were presented at the 2012 ASH Annual Meeting as abstract 411.
In this study, volasertib in combination with low-dose cytarabine (LDAC) elicited higher rates of objective response and an improvement in event-free survival, when compared to LDAC alone.
Eighty-seven AML patients were assigned to receive volasertib + LDAC (n=42) or LDAC alone (n=45). Patient characteristics were similar between the 2 groups.
The objective response rate was 31% among patients who received volasertib + LDAC and 11.1% in those who received LDAC alone. The complete response rates were 16.7% and 6.7%, respectively.
The median event-free survival was 169 days for patients who received volasertib + LDAC and 69 days for patients who received LDAC alone.
Grade 3 or higher adverse events were more common in the volasertib + LDAC arm than the LDAC-alone arm—95.2% vs 68.9%.
The most frequent adverse events of any grade occurring in the volasertib + LDAC arm were febrile neutropenia (50%), constipation (45.2%), nausea (40.5%), and anemia (40.5%).
In the LDAC-alone arm, the most common adverse events were nausea (33.3%), anemia (28.9%), pyrexia (28.9%), constipation (26.7%), asthenia (26.7%), and diarrhea (26.7%).
Based on these results, researchers initiated a phase 3 study, called POLO-AML-2, comparing volasertib plus LDAC to LDAC plus placebo in older AML patients.
Credit: NIH
The US Food and Drug Administration and the European Commission have granted volasertib orphan designation for the treatment of acute myeloid leukemia (AML).
Volasertib, an investigational inhibitor of polo-like kinase 1 (Plk1), works by arresting the cell cycle and inducing apoptosis.
The drug is under evaluation as a potential treatment for patients aged 65 or older with previously untreated AML who are ineligible for intensive remission induction therapy.
In both the US and the European Union, orphan designation is awarded for drugs intended to treat rare conditions for which no authorized treatment exists. The designation gives the company developing volasertib, Boehringer Ingelheim, regulatory support and incentives to help the development and authorization process.
Volasertib has already been tested in a phase 1/2 trial of patients with newly diagnosed AML who were considered ineligible for intensive remission induction therapy. The results were presented at the 2012 ASH Annual Meeting as abstract 411.
In this study, volasertib in combination with low-dose cytarabine (LDAC) elicited higher rates of objective response and an improvement in event-free survival, when compared to LDAC alone.
Eighty-seven AML patients were assigned to receive volasertib + LDAC (n=42) or LDAC alone (n=45). Patient characteristics were similar between the 2 groups.
The objective response rate was 31% among patients who received volasertib + LDAC and 11.1% in those who received LDAC alone. The complete response rates were 16.7% and 6.7%, respectively.
The median event-free survival was 169 days for patients who received volasertib + LDAC and 69 days for patients who received LDAC alone.
Grade 3 or higher adverse events were more common in the volasertib + LDAC arm than the LDAC-alone arm—95.2% vs 68.9%.
The most frequent adverse events of any grade occurring in the volasertib + LDAC arm were febrile neutropenia (50%), constipation (45.2%), nausea (40.5%), and anemia (40.5%).
In the LDAC-alone arm, the most common adverse events were nausea (33.3%), anemia (28.9%), pyrexia (28.9%), constipation (26.7%), asthenia (26.7%), and diarrhea (26.7%).
Based on these results, researchers initiated a phase 3 study, called POLO-AML-2, comparing volasertib plus LDAC to LDAC plus placebo in older AML patients.
Molecule shows preclinical activity in leukemias, lymphomas
SAN DIEGO—A small molecule that has previously proven effective against solid tumors exhibits activity against leukemias and lymphomas, preclinical research suggests.
The molecule, LOR-253, showed antiproliferative activity in a range of leukemia and lymphoma cell lines, induced apoptosis in acute myeloid leukemia (AML) in vitro, and demonstrated synergy with chemotherapeutic agents.
Ronnie Lum, PhD, and colleagues at Lorus Therapeutics, Inc., the Toronto, Canada-based company developing LOR-253, presented these results at the AACR Annual Meeting 2014 (abstract 4544).
LOR-253 acts through induction of the innate tumor suppressor KLF4. Recent research has suggested that upregulation of the transcription factor CDX2 drives the development or progression of leukemic disease. And CDX2 has been shown to silence KLF4, which is reported to be a critical oncogenic event in AML.
Wih this in mind, the researchers decided to test LOR-253’s activity against AML and other hematologic malignancies in vitro.
Experiments revealed that LOR-253 exerts antiproliferative activity against a range of leukemia and lymphoma cell lines, including Ramos, Raji, K-562, Jurkat, MOLT-4, CCRF-CEM, HEL92.1.7, MOLM-13, THP-1, MV411, NB4, HL-60, KG-1, NOMO-1, SKM-1, OCI-AML-2, EOL-1, and Kasumi-1.
IC50 values were substantially lower in these cell lines than in melanoma cell lines, as well as lines of lung, bladder, colon, prostate, and breast cancers.
The researchers also found that LOR-253 induces KLF4 mRNA expression in the AML cell lines HL60 and THP1. This prompts increased expression of p21, a cyclin-dependent kinase inhibitor that is transcriptionally regulated by KLF4.
Consistent with these results, LOR-253 induced cell-cycle arrest and apoptosis in the AML cell lines, which suggests the molecule acted through its intended mechanism of action.
LOR-253 also showed “strong anticancer synergy” in HL60 cells when delivered in combination with daunorubicin, azacitidine, decitabine, or cytarabine.
When LOR-253 was delivered concurrently with chemotherapy, cell viability decreased the most with cytarabine, followed by decitabine, azacitidine, and daunorubicin. With sequential treatment, cell viability decreased the most when LOR-253 was delivered with decitabine, followed by azacitidine, cytarabine, and daunorubicin.
The researchers said these results suggest LOR-253 could provide a new approach to treat AML and, possibly, other hematologic malignancies.
They are now conducting studies to further characterize the pathway that mediates KLF4 induction by LOR-253, to characterize the effects of LOR-253 in combination with approved chemotherapies for AML, and to assess the efficacy of LOR-253 in animal models of AML.
Lorus Therapeutics is also planning a dose-escalating, phase 1b trial of LOR-253 as monotherapy in AML, myelodysplastic syndromes, and other hematologic malignancies. The company expects to begin the trial this summer.
SAN DIEGO—A small molecule that has previously proven effective against solid tumors exhibits activity against leukemias and lymphomas, preclinical research suggests.
The molecule, LOR-253, showed antiproliferative activity in a range of leukemia and lymphoma cell lines, induced apoptosis in acute myeloid leukemia (AML) in vitro, and demonstrated synergy with chemotherapeutic agents.
Ronnie Lum, PhD, and colleagues at Lorus Therapeutics, Inc., the Toronto, Canada-based company developing LOR-253, presented these results at the AACR Annual Meeting 2014 (abstract 4544).
LOR-253 acts through induction of the innate tumor suppressor KLF4. Recent research has suggested that upregulation of the transcription factor CDX2 drives the development or progression of leukemic disease. And CDX2 has been shown to silence KLF4, which is reported to be a critical oncogenic event in AML.
Wih this in mind, the researchers decided to test LOR-253’s activity against AML and other hematologic malignancies in vitro.
Experiments revealed that LOR-253 exerts antiproliferative activity against a range of leukemia and lymphoma cell lines, including Ramos, Raji, K-562, Jurkat, MOLT-4, CCRF-CEM, HEL92.1.7, MOLM-13, THP-1, MV411, NB4, HL-60, KG-1, NOMO-1, SKM-1, OCI-AML-2, EOL-1, and Kasumi-1.
IC50 values were substantially lower in these cell lines than in melanoma cell lines, as well as lines of lung, bladder, colon, prostate, and breast cancers.
The researchers also found that LOR-253 induces KLF4 mRNA expression in the AML cell lines HL60 and THP1. This prompts increased expression of p21, a cyclin-dependent kinase inhibitor that is transcriptionally regulated by KLF4.
Consistent with these results, LOR-253 induced cell-cycle arrest and apoptosis in the AML cell lines, which suggests the molecule acted through its intended mechanism of action.
LOR-253 also showed “strong anticancer synergy” in HL60 cells when delivered in combination with daunorubicin, azacitidine, decitabine, or cytarabine.
When LOR-253 was delivered concurrently with chemotherapy, cell viability decreased the most with cytarabine, followed by decitabine, azacitidine, and daunorubicin. With sequential treatment, cell viability decreased the most when LOR-253 was delivered with decitabine, followed by azacitidine, cytarabine, and daunorubicin.
The researchers said these results suggest LOR-253 could provide a new approach to treat AML and, possibly, other hematologic malignancies.
They are now conducting studies to further characterize the pathway that mediates KLF4 induction by LOR-253, to characterize the effects of LOR-253 in combination with approved chemotherapies for AML, and to assess the efficacy of LOR-253 in animal models of AML.
Lorus Therapeutics is also planning a dose-escalating, phase 1b trial of LOR-253 as monotherapy in AML, myelodysplastic syndromes, and other hematologic malignancies. The company expects to begin the trial this summer.
SAN DIEGO—A small molecule that has previously proven effective against solid tumors exhibits activity against leukemias and lymphomas, preclinical research suggests.
The molecule, LOR-253, showed antiproliferative activity in a range of leukemia and lymphoma cell lines, induced apoptosis in acute myeloid leukemia (AML) in vitro, and demonstrated synergy with chemotherapeutic agents.
Ronnie Lum, PhD, and colleagues at Lorus Therapeutics, Inc., the Toronto, Canada-based company developing LOR-253, presented these results at the AACR Annual Meeting 2014 (abstract 4544).
LOR-253 acts through induction of the innate tumor suppressor KLF4. Recent research has suggested that upregulation of the transcription factor CDX2 drives the development or progression of leukemic disease. And CDX2 has been shown to silence KLF4, which is reported to be a critical oncogenic event in AML.
Wih this in mind, the researchers decided to test LOR-253’s activity against AML and other hematologic malignancies in vitro.
Experiments revealed that LOR-253 exerts antiproliferative activity against a range of leukemia and lymphoma cell lines, including Ramos, Raji, K-562, Jurkat, MOLT-4, CCRF-CEM, HEL92.1.7, MOLM-13, THP-1, MV411, NB4, HL-60, KG-1, NOMO-1, SKM-1, OCI-AML-2, EOL-1, and Kasumi-1.
IC50 values were substantially lower in these cell lines than in melanoma cell lines, as well as lines of lung, bladder, colon, prostate, and breast cancers.
The researchers also found that LOR-253 induces KLF4 mRNA expression in the AML cell lines HL60 and THP1. This prompts increased expression of p21, a cyclin-dependent kinase inhibitor that is transcriptionally regulated by KLF4.
Consistent with these results, LOR-253 induced cell-cycle arrest and apoptosis in the AML cell lines, which suggests the molecule acted through its intended mechanism of action.
LOR-253 also showed “strong anticancer synergy” in HL60 cells when delivered in combination with daunorubicin, azacitidine, decitabine, or cytarabine.
When LOR-253 was delivered concurrently with chemotherapy, cell viability decreased the most with cytarabine, followed by decitabine, azacitidine, and daunorubicin. With sequential treatment, cell viability decreased the most when LOR-253 was delivered with decitabine, followed by azacitidine, cytarabine, and daunorubicin.
The researchers said these results suggest LOR-253 could provide a new approach to treat AML and, possibly, other hematologic malignancies.
They are now conducting studies to further characterize the pathway that mediates KLF4 induction by LOR-253, to characterize the effects of LOR-253 in combination with approved chemotherapies for AML, and to assess the efficacy of LOR-253 in animal models of AML.
Lorus Therapeutics is also planning a dose-escalating, phase 1b trial of LOR-253 as monotherapy in AML, myelodysplastic syndromes, and other hematologic malignancies. The company expects to begin the trial this summer.
Dual kinase inhibitor targets heterogeneity in AML
SAN DIEGO—A dual kinase inhibitor shows potential for treating the heterogeneous acute myeloid leukemia (AML) population, researchers say.
The inhibitor, SEL24-B489, targets both PIM and FLT3 mutants. In experiments, it exhibited more consistent activity across AML cell lines than inhibitors directed only at PIM or FLT3.
SEL24-B489 also demonstrated synergistic activity with cytarabine, both in AML cell lines and mouse models of the disease.
The researchers believe these results suggest SEL24-B489 could potentially treat a range of AML patients and might prove effective regardless of FLT3 status.
“When you have a very heterogeneous population of AML patients, some of them have different FLT mutations, and the problem with FLT inhibitors has been the resistance that occurs in the tyrosine kinase domain,” said Krzysztof D. Brzózka, PhD, of Selvita, the Kraków, Poland-based company developing SEL24-B489.
“We believe that since FLT is upstream, and PIM kinases are downstream of the FLT signaling, we will have higher chances
of overcoming resistance because we are targeting the same pathway at 2 independent nodes.”
Dr Brzózka and his colleagues presented research to support this theory at the AACR Annual Meeting 2014 as abstract 1749.*
The researchers evaluated SEL24-B489 in a range of AML cell lines: MV4-11, MOLM-13, MOLM-16, KG-1, CMK, and HL-60. The drug showed “strong cytotoxicity” across the cell lines, independent of FLT3 status.
The team also compared SEL24-B489 to the PIM inhibitor AZD1208 and the FLT3 inhibitor AC220 in MV4-11 cell lines and MOLM-16 cell lines.
In MV4-11 cells, the IC50 was 0.003 μM for AC220, 0.15 μM for SEL24-B489, and 2.24 μM for AZD1208. In MOLM-16 cells, the IC50 was 0.07 μM for AZD1208, 0.1 μM for SEL24-B489, and >10 μM for AC220.
The researchers then evaluated SEL24-B489 in combination with cytarabine.
“The molecule shows very strong synergistic effects with cytarabine, both in vitro and in vivo,” Dr Brzózka said. “The combination index in vitro is approximately 0.1, 0.2. And in vivo, that translates to [nearly] 100% tumor growth inhibition.”
Tumor growth inhibition (TGI) measured 60% when mice received cytarabine alone at 50 mg/kg. TGI was 77% with SEL24-B489 alone at 25 mg/kg and 82% with SEL24-B489 alone at 50 mg/kg.
But with 25 mg/kg of SEL24-B489 and 50 mg/kg of cytarabine, TGI was 89%. And when both drugs were given at 50 mg/kg, TGI was 99%.
The researchers also assessed SEL24-B489 alone in mouse models of AML. In mice injected with MV4-11 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 50%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 80%.
In mice injected with MOLM-16 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 80%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 100%.
Finally, the team evaluated the safety of SEL24-B489 via repeated 5-day and 10-day toxicology studies in rats.
And they concluded that doses of 100 mg/kg QD x 5 and 25 mg/kg BID x 10 were safe, based on data concerning body weight gain, as well as results of clinical chemistry, hematology, necropsy, and histological analyses.
“Overall, SEL24-B489 has very good oral bioavailability and initial safety profiling,” Dr Brzózka said. “Both in vitro and in vivo, it shows a pretty promising therapeutic index.”
He and his colleagues are now studying SEL24-B489 in dogs, and Selvita is looking for a partner company to help move the drug to phase 1 trials.
*Information in the abstract differs from that presented at the meeting.
SAN DIEGO—A dual kinase inhibitor shows potential for treating the heterogeneous acute myeloid leukemia (AML) population, researchers say.
The inhibitor, SEL24-B489, targets both PIM and FLT3 mutants. In experiments, it exhibited more consistent activity across AML cell lines than inhibitors directed only at PIM or FLT3.
SEL24-B489 also demonstrated synergistic activity with cytarabine, both in AML cell lines and mouse models of the disease.
The researchers believe these results suggest SEL24-B489 could potentially treat a range of AML patients and might prove effective regardless of FLT3 status.
“When you have a very heterogeneous population of AML patients, some of them have different FLT mutations, and the problem with FLT inhibitors has been the resistance that occurs in the tyrosine kinase domain,” said Krzysztof D. Brzózka, PhD, of Selvita, the Kraków, Poland-based company developing SEL24-B489.
“We believe that since FLT is upstream, and PIM kinases are downstream of the FLT signaling, we will have higher chances
of overcoming resistance because we are targeting the same pathway at 2 independent nodes.”
Dr Brzózka and his colleagues presented research to support this theory at the AACR Annual Meeting 2014 as abstract 1749.*
The researchers evaluated SEL24-B489 in a range of AML cell lines: MV4-11, MOLM-13, MOLM-16, KG-1, CMK, and HL-60. The drug showed “strong cytotoxicity” across the cell lines, independent of FLT3 status.
The team also compared SEL24-B489 to the PIM inhibitor AZD1208 and the FLT3 inhibitor AC220 in MV4-11 cell lines and MOLM-16 cell lines.
In MV4-11 cells, the IC50 was 0.003 μM for AC220, 0.15 μM for SEL24-B489, and 2.24 μM for AZD1208. In MOLM-16 cells, the IC50 was 0.07 μM for AZD1208, 0.1 μM for SEL24-B489, and >10 μM for AC220.
The researchers then evaluated SEL24-B489 in combination with cytarabine.
“The molecule shows very strong synergistic effects with cytarabine, both in vitro and in vivo,” Dr Brzózka said. “The combination index in vitro is approximately 0.1, 0.2. And in vivo, that translates to [nearly] 100% tumor growth inhibition.”
Tumor growth inhibition (TGI) measured 60% when mice received cytarabine alone at 50 mg/kg. TGI was 77% with SEL24-B489 alone at 25 mg/kg and 82% with SEL24-B489 alone at 50 mg/kg.
But with 25 mg/kg of SEL24-B489 and 50 mg/kg of cytarabine, TGI was 89%. And when both drugs were given at 50 mg/kg, TGI was 99%.
The researchers also assessed SEL24-B489 alone in mouse models of AML. In mice injected with MV4-11 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 50%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 80%.
In mice injected with MOLM-16 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 80%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 100%.
Finally, the team evaluated the safety of SEL24-B489 via repeated 5-day and 10-day toxicology studies in rats.
And they concluded that doses of 100 mg/kg QD x 5 and 25 mg/kg BID x 10 were safe, based on data concerning body weight gain, as well as results of clinical chemistry, hematology, necropsy, and histological analyses.
“Overall, SEL24-B489 has very good oral bioavailability and initial safety profiling,” Dr Brzózka said. “Both in vitro and in vivo, it shows a pretty promising therapeutic index.”
He and his colleagues are now studying SEL24-B489 in dogs, and Selvita is looking for a partner company to help move the drug to phase 1 trials.
*Information in the abstract differs from that presented at the meeting.
SAN DIEGO—A dual kinase inhibitor shows potential for treating the heterogeneous acute myeloid leukemia (AML) population, researchers say.
The inhibitor, SEL24-B489, targets both PIM and FLT3 mutants. In experiments, it exhibited more consistent activity across AML cell lines than inhibitors directed only at PIM or FLT3.
SEL24-B489 also demonstrated synergistic activity with cytarabine, both in AML cell lines and mouse models of the disease.
The researchers believe these results suggest SEL24-B489 could potentially treat a range of AML patients and might prove effective regardless of FLT3 status.
“When you have a very heterogeneous population of AML patients, some of them have different FLT mutations, and the problem with FLT inhibitors has been the resistance that occurs in the tyrosine kinase domain,” said Krzysztof D. Brzózka, PhD, of Selvita, the Kraków, Poland-based company developing SEL24-B489.
“We believe that since FLT is upstream, and PIM kinases are downstream of the FLT signaling, we will have higher chances
of overcoming resistance because we are targeting the same pathway at 2 independent nodes.”
Dr Brzózka and his colleagues presented research to support this theory at the AACR Annual Meeting 2014 as abstract 1749.*
The researchers evaluated SEL24-B489 in a range of AML cell lines: MV4-11, MOLM-13, MOLM-16, KG-1, CMK, and HL-60. The drug showed “strong cytotoxicity” across the cell lines, independent of FLT3 status.
The team also compared SEL24-B489 to the PIM inhibitor AZD1208 and the FLT3 inhibitor AC220 in MV4-11 cell lines and MOLM-16 cell lines.
In MV4-11 cells, the IC50 was 0.003 μM for AC220, 0.15 μM for SEL24-B489, and 2.24 μM for AZD1208. In MOLM-16 cells, the IC50 was 0.07 μM for AZD1208, 0.1 μM for SEL24-B489, and >10 μM for AC220.
The researchers then evaluated SEL24-B489 in combination with cytarabine.
“The molecule shows very strong synergistic effects with cytarabine, both in vitro and in vivo,” Dr Brzózka said. “The combination index in vitro is approximately 0.1, 0.2. And in vivo, that translates to [nearly] 100% tumor growth inhibition.”
Tumor growth inhibition (TGI) measured 60% when mice received cytarabine alone at 50 mg/kg. TGI was 77% with SEL24-B489 alone at 25 mg/kg and 82% with SEL24-B489 alone at 50 mg/kg.
But with 25 mg/kg of SEL24-B489 and 50 mg/kg of cytarabine, TGI was 89%. And when both drugs were given at 50 mg/kg, TGI was 99%.
The researchers also assessed SEL24-B489 alone in mouse models of AML. In mice injected with MV4-11 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 50%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 80%.
In mice injected with MOLM-16 cells, SEL24-B489 at 25 mg/kg BID reduced tumor volume by more than 80%, when compared to untreated control mice. And SEL24-B489 at 75 mg/kg BID reduced tumor volume by more than 100%.
Finally, the team evaluated the safety of SEL24-B489 via repeated 5-day and 10-day toxicology studies in rats.
And they concluded that doses of 100 mg/kg QD x 5 and 25 mg/kg BID x 10 were safe, based on data concerning body weight gain, as well as results of clinical chemistry, hematology, necropsy, and histological analyses.
“Overall, SEL24-B489 has very good oral bioavailability and initial safety profiling,” Dr Brzózka said. “Both in vitro and in vivo, it shows a pretty promising therapeutic index.”
He and his colleagues are now studying SEL24-B489 in dogs, and Selvita is looking for a partner company to help move the drug to phase 1 trials.
*Information in the abstract differs from that presented at the meeting.
Compound is potent FLT3 inhibitor, team says
Credit: Rhoda Baer
An experimental compound called TTT-3002 could be “one of the most potent FLT3 inhibitors to date,” according to researchers.
In preclinical experiments, TTT-3002 proved more active than the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 blocked FLT3 activity in human FLT3/ITD mutant leukemia cell lines, prolonged survival in a mouse model of FLT3-associated acute myeloid leukemia (AML), and proved toxic to leukemic cells from patients with AML.
Donald Small, MD, PhD, of Johns Hopkins University School of Medicine in Baltimore, and his colleagues reported these results in Blood.
“We’re very excited about TTT-3002, because it appears in our tests so far to be the most potent FLT3 inhibitor to date,” Dr Small said. “It showed activity against FLT3-mutated cells taken from patients and with minimal toxicity to normal bone marrow cells, making it a promising new candidate for the treatment of AML.”
In a series of experiments, the researchers found that the amount of TTT-3002 needed to block FLT3 activity in human leukemia cell lines was 6- to 7-fold lower than for ACC220, the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 also inhibited proteins made by genes further down the FLT3 signaling pathway, including STAT5, AKT, and MAPK. And it showed activity against the most frequently occurring FLT3 mutations, FLT3/ITD and FLT3/D835Y. (Many other inhibitors are ineffective against FLT3/D835Y mutations.)
When the researchers tested TTT-3002 in a mouse model of leukemia, they found the drug eliminated the presence of leukemic cells within 10 days of treatment.
Mice lived an average of more than 100 days after TTT-3002 treatment and resumed normal bone marrow activity. In comparison, mice treated with a placebo died an average of 18 days after treatment.
The researchers also found that TTT-3002 was toxic to leukemia samples taken from newly diagnosed and relapsed patients with AML, but it did not affect normal bone marrow cells taken from healthy donors.
A single dose of TTT-3002 caused more than 90% inhibition against FLT3 signaling that lasted for 12 hours.
Credit: Rhoda Baer
An experimental compound called TTT-3002 could be “one of the most potent FLT3 inhibitors to date,” according to researchers.
In preclinical experiments, TTT-3002 proved more active than the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 blocked FLT3 activity in human FLT3/ITD mutant leukemia cell lines, prolonged survival in a mouse model of FLT3-associated acute myeloid leukemia (AML), and proved toxic to leukemic cells from patients with AML.
Donald Small, MD, PhD, of Johns Hopkins University School of Medicine in Baltimore, and his colleagues reported these results in Blood.
“We’re very excited about TTT-3002, because it appears in our tests so far to be the most potent FLT3 inhibitor to date,” Dr Small said. “It showed activity against FLT3-mutated cells taken from patients and with minimal toxicity to normal bone marrow cells, making it a promising new candidate for the treatment of AML.”
In a series of experiments, the researchers found that the amount of TTT-3002 needed to block FLT3 activity in human leukemia cell lines was 6- to 7-fold lower than for ACC220, the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 also inhibited proteins made by genes further down the FLT3 signaling pathway, including STAT5, AKT, and MAPK. And it showed activity against the most frequently occurring FLT3 mutations, FLT3/ITD and FLT3/D835Y. (Many other inhibitors are ineffective against FLT3/D835Y mutations.)
When the researchers tested TTT-3002 in a mouse model of leukemia, they found the drug eliminated the presence of leukemic cells within 10 days of treatment.
Mice lived an average of more than 100 days after TTT-3002 treatment and resumed normal bone marrow activity. In comparison, mice treated with a placebo died an average of 18 days after treatment.
The researchers also found that TTT-3002 was toxic to leukemia samples taken from newly diagnosed and relapsed patients with AML, but it did not affect normal bone marrow cells taken from healthy donors.
A single dose of TTT-3002 caused more than 90% inhibition against FLT3 signaling that lasted for 12 hours.
Credit: Rhoda Baer
An experimental compound called TTT-3002 could be “one of the most potent FLT3 inhibitors to date,” according to researchers.
In preclinical experiments, TTT-3002 proved more active than the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 blocked FLT3 activity in human FLT3/ITD mutant leukemia cell lines, prolonged survival in a mouse model of FLT3-associated acute myeloid leukemia (AML), and proved toxic to leukemic cells from patients with AML.
Donald Small, MD, PhD, of Johns Hopkins University School of Medicine in Baltimore, and his colleagues reported these results in Blood.
“We’re very excited about TTT-3002, because it appears in our tests so far to be the most potent FLT3 inhibitor to date,” Dr Small said. “It showed activity against FLT3-mutated cells taken from patients and with minimal toxicity to normal bone marrow cells, making it a promising new candidate for the treatment of AML.”
In a series of experiments, the researchers found that the amount of TTT-3002 needed to block FLT3 activity in human leukemia cell lines was 6- to 7-fold lower than for ACC220, the most potent FLT3 inhibitor currently in clinical trials.
TTT-3002 also inhibited proteins made by genes further down the FLT3 signaling pathway, including STAT5, AKT, and MAPK. And it showed activity against the most frequently occurring FLT3 mutations, FLT3/ITD and FLT3/D835Y. (Many other inhibitors are ineffective against FLT3/D835Y mutations.)
When the researchers tested TTT-3002 in a mouse model of leukemia, they found the drug eliminated the presence of leukemic cells within 10 days of treatment.
Mice lived an average of more than 100 days after TTT-3002 treatment and resumed normal bone marrow activity. In comparison, mice treated with a placebo died an average of 18 days after treatment.
The researchers also found that TTT-3002 was toxic to leukemia samples taken from newly diagnosed and relapsed patients with AML, but it did not affect normal bone marrow cells taken from healthy donors.
A single dose of TTT-3002 caused more than 90% inhibition against FLT3 signaling that lasted for 12 hours.