SITC 2019: Using Activated Natural Killer Cells to Treat Merkel Cell Carcinoma
Posted: Thursday, November 14, 2019
Based on a phase II trial, activated natural killer cell therapy, with or without the interleukin-15 superagonist N-803, appears to be well tolerated and provided a clinical benefit to three of seven patients with metastatic Merkel cell carcinoma. Sunandana Chandra, MD, of Northwestern University Feinberg School of Medicine in Chicago, presented the final results of this study at the 2019 Society for Immunotherapy of Cancer (SITC) Annual Meeting in National Harbor, Maryland (Abstract O19).
“As natural killer cells can eliminate tumors with deficient MHC-I, a common evasion mechanism for Merkel cell carcinoma, they hold potential for treatment of this disease,” according to a SITC press release. “The results from this study [will] lay the groundwork for future investigation of this agent.”
Patients with unresectable stage III or IV Merkel cell carcinoma were administered either activated natural killer cell monotherapy or N-803 injection before the infusion of natural killer cells. Of the seven total subjects enrolled, four received both therapies, and three received activated natural killer cells alone.
One of the patients achieved a partial response, and one achieved an unconfirmed complete response. In addition, one patient had stable disease that lasted for 5.5 months. One patient who had become refractory to pembrolizumab before study enrollment experienced a clinical and radiologic complete response at 4 months with the natural killer cell monotherapy. This patient then developed progressive disease at 6 months, resulting in treatment discontinuation; however, rechallenge with pembrolizumab resulted in a durable complete response, ongoing at 36 months.
Biopsy revealed increased CD8 and CD4 T-cell infiltration along with increased expression of immune cell markers, antigen-presenting genes, and interferon-gamma genes. The treatment was considered to be safe, with no patients experiencing immune-related adverse events or any treatment-related grade 3 or higher adverse events.
Disclosure: Dr. Chandra reported consulting and advisory board roles with Array BioPharma, Bristol-Myers Squibb, EMD Serono, and Regeneron. For full disclosures of other study authors, visit sitcancer.org.