Pembrolizumab Improves Survival, Tumor Control in Advanced Merkel Cell Carcinoma

Pembrolizumab (Keytruda), an immunotherapy, showed durable tumor control and overall survival as a first-line treatment for advanced Merkel cell carcinoma (MCC), an aggressive skin cancer, according to new data from a phase 2 trial.

Although MCC is rare, incidence has increased by 95% between 2000 and 2013. The 5-year survival rate for advanced disease ranges between 14% and 27%.

The study, which was published in the Journal of Clinical Oncology, included 50 adults naïve to systemic therapy for advanced MCC who received pembrolizumab (2 mg/kg every 3 weeks) for up to 2 years. Among the 50 patients, 64% had Merkel cell polyomavirus-positive tumors. In total, 56% of patients responded to the treatment, 24% had a complete response, and 32% had a partial response. The overall response rate in virus-positive tumors was 59% and 53% in virus-negative tumors, according to the data. The average length of progression-free survival was 26.8 months, with a 24-month rate of 48.3%, and a 24-month overall survival rate of 68.7%.

“This study shows the amazing ability of our immune system to fight off and destroy an aggressive form of skin cancer called Merkel cell carcinoma,” lead study author Adam Riker, MD, FACS, professor and chief of surgical oncology, said in a statement. “The study drug, pembrolizumab, which is a new form of immunotherapy, blocks a specific receptor in our bodies, resulting in a super charging of our immune system to both recognize and destroy cancer cells. The overall impressive results show that this form of immunotherapy is quite effective, giving us an important treatment option for patients with Merkel cell carcinoma that has spread within the body.”

According to the study, nearly all of the patients experienced some type of treatment-related adverse effect and 7 patients discontinued the trial. Additionally, 1 death occurred in a 73-year old patient with widely metastatic MCC and pre-existing atrial fibrillation who withdrew from the trial and died 10 days after a single infusion of pembrolizumab.

The findings present the longest observation to date of patients with advanced MCC receiving first-line anti-programmed cell death-1 therapy, the authors wrote in the study. Compared with historical data from patients treated with first-line chemotherapy, pembrolizumab demonstrated durable tumor control, a generally tolerable safety profile, and a favorable overall survival, they concluded.

References

Nghiem P, Bhatia S, Lipson EJ, et al. Durable tumor regression and overall survival in patients with advanced merkel cell carcinoma receiving pembrolizumab as first-line therapy. 2019. Journal of Clinical Oncology. https://doi.org/10.1200/JCO.18.01896

Immunotherapy Drug Used As 1^st-Line Therapy for Merkel Cell Carcinoma Improved Survival [news release]. LSU Health. https://www.lsuhsc.edu/newsroom/Immunotherapy%20Drug%20Used%20As%201st-Line%20Therapy%20for%20Merkel%20Cell%20Carcinoma%20Improved%20Survival.html. Accessed February 7, 2019.