Conference Coverage

MCC response varies based on immunosuppression type, especially CLL



Patients with Merkel cell carcinoma and chronic immunosuppression may fare better or worse on immunotherapy based on the reason for immunosuppression, according to recent research at the annual meeting of the Society for Investigative Dermatology, held virtually.

About 10% of patients with Merkel cell carcinoma (MCC) are immunosuppressed at diagnosis, and these patients tend to have a more aggressive disease course and worse disease-specific survival compared with immunocompetent patients, Lauren Zawacki, a research assistant in the Nghiem Lab at the University of Washington, Seattle, said in her presentation. Although patients are receiving immune checkpoint inhibitors such as anti-PD-1 and anti-PD-L1 as treatments, the efficacy and side effects on immunosuppressed patients have not been well studied because many of these patients are not eligible for clinical trials.

Ms. Zawacki and colleagues analyzed data from a prospective Seattle registry of 1,442 patients with MCC, identifying 179 patients with MCC who had chronic immunosuppression due to chronic lymphocytic leukemia (CLL), solid organ transplants, autoimmune disorders, other hematological malignancies, and HIV and AIDS. Non-Hodgkin lymphoma comprised 7 of 8 patients in the group with other hematological malignancies, and Crohn’s disease made up 5 of 6 patients in the autoimmune disorder group. Of the 179 patients with MCC and immunosuppression, 31 patients were treated with either anti-PD-1 or anti-PD-L1 therapy.

There was an objective response rate of 52%, with 14 patients having a complete response, 2 patients having a partial response, and 15 patients experiencing disease progression. Of the patients with disease progression, 11 died of MCC. The response rate in immunocompromised patients is similar to results seen by her group in immunocompetent patients (Nghiem P et al. N Engl J Med 2016; 374:2542-52), said Ms. Zawacki. “While the overall objective response rate is comparable between immunocompetent and immunosuppressed patients, the response rates vary greatly between the different types of immunosuppression,” she said.

When grouping response rates by immunosuppression type, they found 2 of 11 patients with CLL (18%) and 2 of 6 patients with autoimmune disease (33%) had an objective response, while 2 of 3 patients with HIV/AIDS (66%) and 7 of 7 patients with other hematologic malignancies (100%) had an objective response.

“While the numbers of the cohort are small, there still seems to be a considerable difference in the response rate between the different types of immune suppression, which is critical when we’re treating patients who typically have a more aggressive disease course,” said Ms. Zawacki.

In particular, the finding of no patients with MCC and CLL achieving a complete response interested Ms. Zawacki and her colleagues, since about one-fourth of patients in the Seattle registry have this combination of disease. “Not only did none of the CLL patients have a complete response, but 7 out of the 11 patients with CLL died from MCC,” she explained. When examining further, the researchers found 45% of patients in this group discontinued because of side effects of immunotherapy and had a median time to recurrence of 1.5 months. “This finding suggests that CLL in particular plays a large role in impairing the function of the immune system, leading to not only a more aggressive disease course, but a poorer response to immunotherapy,” she said.

“There is a significant need for improved interventions for patients with CLL and autoimmune disorders,” she added. “Research for immunosuppressed patients is critical given the associated aggressive disease course and their lack of inclusion in clinical trials.”

Ms. Zawacki acknowledged the small number of patients in the study as a limitation, and patients who received follow-up at outside facilities may have received slightly different care, which could impact adverse event reporting or reasons for study discontinuation.

“A multi-institutional study would be beneficial to expand the number of patients in that cohort and to help confirm the trend observed in this study. In addition, future studies should assess the role of combination systemic therapy, such as neutron radiation and immunotherapy together in order to see if the objective response can be approved among immunosuppressed patients,” she said.

This study was supported by funding from the MCC Patient Gift Fund, the National Cancer Institute, and a grant from NIH. Ms. Zawacki reports no relevant conflicts of interest.

SOURCE: Zawacki L. SID 2020, Abstract 497.

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