A heterogenous disease with few treatment options and poor outcomes, mTNBC has an incidence rate twice as high in Black as in White women.
Black women with mTNBC may also experience worse outcomes than other groups, with a greater risk of mortality related to disparities in access to health care and in income, delays in treatment, a higher prevalence of comorbidities, and differences in tumor biology.
Previously presented data from the phase 3 ASCENT trial showed that SG nearly doubled overall survival versus single-agent chemotherapy in pretreated women with mTNBC, with the benefit observed across patient subgroups.
Based on these findings, the Food and Drug Administration approved SG for patients with mTNBC who have received at least two prior chemotherapies, at least one of which is to have been given in the metastatic setting.
Now, an analysis of the ASCENT data in just over 60 Black women with mTNBC showed that they can expect to see their progression-free survival (PFS) improve by 56% and their overall survival increase by a nonsignificant 36% when given SG as opposed to single-agent chemotherapy.
The research (abstract P5-16-07) was presented at the San Antonio Breast Cancer Symposium on Dec. 10.
The team says that Black women with mTNBC “derived a similar clinical benefit” from SG versus chemotherapy to other women in the study, and had a “manageable” safety profile, which was “consistent with the full trial population.”
Consequently, SG “should be considered a treatment option for Black patients with mTNBC who have received ≥ 2 prior chemotherapies,” at least one of which having been given in the metastatic setting.
Lead researcher Lisa A. Carey, MD, told this news organiztion that it is “very important” to show that the drug works in Black patients, adding: “We know that certain drugs don’t perform so well and it’s also true that people of color are particularly affected by TNBC.”
She said there were “only 62” Black patients in ASCENT, “so if you look at the entire trial and make assumptions that the drug performs the same in all the subsets, then sometimes you’re wrong.”
Dr. Carey, the Richardson and Marilyn Jacobs Preyer Distinguished Professor in Breast Cancer Research, UNC Lineberger Comprehensive Cancer Center, Chapel Hill, N.C., said there is “emerging interest” in racial disparities in cancer outcomes.
“Black patients have more trouble with access to care,” she said, noting that “in trial populations, [the outcomes] generally seem similar because the patients who go onto the trials tend to be those that can participate, but you never know until you look.”
Overall, Dr. Carey said the current results suggest that, “at least from the standpoint of the therapeutic implications of this drug – which is really a pretty remarkable drug in the overall study – it behaves very similarly in this group.”
Jennifer K. Litton, MD, vice president of clinical research at University of Texas MD Anderson Cancer Center, Houston, said: “We have known that minority patients, especially Black patients, have a higher rate of triple negative breast cancer and aggressive biologies, and have had worse breast cancer outcomes in many published series.”
She told this news organization that, “additionally, they are often underrepresented in breast cancer clinical trials.”
Dr. Litton said “the very favorable outcomes” reported in “this important subset of patients who participated in the ASCENT trial” confirm the use of SG in patients with mTNBC.
To examine the clinical outcomes of Black patients in the ASCENT study, the team conduced a prespecified analysis of participants self-reporting Black race who had been randomized to SG or single-agent chemotherapy of physician’s choice, including those with and without brain metastases.
Of the 529 patients enrolled to ASCENT, 62 (12%) were Black, of whom 28 were assigned to SG and 34 to single agent chemotherapy. The two groups were generally well balanced, although six patients in the chemotherapy arm had known brain metastases at baseline versus none of those given SG.
After a median treatment duration of 5.3 months with SG and 1.6 months for single-agent chemotherapy, there was a significant improvement in PFS with SG, at 5.4 months versus 2.2 months for chemotherapy, and a hazard ratio of 0.44 (P = .008).
There was also a nonsignificant improvement in overall survival with SG at 13.8 months versus 8.5 months for chemotherapy, and a hazard ratio of 0.64 (P = .159).
The objective response rate was 32% with SG versus 6% in patients given chemotherapy, while the median duration of response was 9.2 months in the SG arm and not evaluable for chemotherapy.
The researchers note that these efficacy findings were “consistent” with those seen in the full ASCENT study population.
In terms of safety, the most common treatment-related adverse events were neutropenia, seen in 64% of SG and 61% of chemotherapy patients, diarrhea in 64% and 13%, respectively, and fatigue, in 52% and 39%, respectively.
The most common grade ≥3 events were neutropenia, in 48% and 42% of SG and chemotherapy patients, respectively, followed by anemia, in 12% and 6%, respectively, leukopenia in 8% and 16%, respectively, and febrile neutropenia in 8% and 3%, respectively.
No treatment-related deaths occurred in either treatment arm.
Dose reduction due to treatment-emergent adverse events was recorded in 28% of patients receiving SG and 35% of those assigned to single-agent chemotherapy, and discontinuations occurred in 0% and 3%, respectively.
The study was sponsored by Gilead Sciences. Dr. Carey reports research funding from Sanofi, Novartis, Genentech/Roche, and GSK; spouse serves on the board of Falcon Therapeutics.