by Dr. C.H. Weaver M.D. Medical Editor update 11/2019
The U.S. Food and Drug Administration (FDA) approved Keytruda (pembrolizumab) for the treatment of patients with recurrent or metastatic cervical cancer with disease progression on or after chemotherapy whose tumors express PD-L1 in 2018. Keytruda was the first "checkpoint inhibitor" anti-PD-1 immunotherapy approved for patients with advanced cervical cancer. (1) Reports also suggest the checkpoint inhibitor Opdivo (nivolumab) produces similar responses.(2)
According to Dr. Bradley Monk, oncologist with Arizona Oncology, medical director of US Oncology Research Gynecology Program and professor of obstetrics and gynecology at University of Arizona’s College of Medicine and Creighton University School of Medicine “Even with the many advances observed across gynecologic cancers, new treatment options have been lacking for previously treated patients with advanced cervical cancer. The approval of immunotherapy for cervical cancer patients is important news – and as an oncologist, it is exciting to see a much needed option made available to these patients.”
About Cervical Cancer
Each year in the United States, more than 12,000 women are diagnosed with cervical cancer and more than 4,000 die of the disease. Traditional chemotherapy drugs have limited effectiveness against advanced cervical cancer, highlighting the importance of finding new ways to treat this disease.
About Keytruda (pembrolizumab)
Keytruda is a monoclonal antibody know as a checkpoint inhibitor that helps to restore the body’s immune system in fighting cancer. It creates its anti-cancer effects by blocking a specific protein used by cancer cells called PD-L1, to escape an attack by the immune system. Once PD-L1 is blocked, cells of the immune system are able to identify cancer cells as a threat and initiate an attack to destroy the cancer. Keytruda is approved for the treatment of several types of cancer.
The current study evaluated 98 patients with recurrent or metastatic cervical cancer in study called Keynote-158. Patients were treated with Keytruda intravenously at a dose of 200 mg every three weeks until unacceptable toxicity or documented disease progression. Among the 98 patients in treated 77 (79%) had tumors that expressed PD-L1 and received at least one line of chemotherapy in the metastatic setting. PD-L1 status was determined using the an FDA approved assay.
For the 77 patients whose tumors expressed PD-L1 the overall response rate was 14.3 percent with a complete response rate of 2.6 percent and partial response rate of 11.7 percent. Among the 11 responding patients, the median duration of response has not yet been reached (range, 4.1 to 18.6+ months) and 91 percent experienced a duration of response of six months or longer. No responses were observed in patients whose tumors did not have PD-L1 expression.
In November 2019 similar results were reported for another checkpoint inhibitor medication called Opdivo. In the phase 1/2 CheckMate 358 clinical trial which evaluated Opdivo in 24 patients with recurrent/metastatic cervical, vaginal, or vulvar cancers. Objective response rates for cervical and vaginal/vulvar cancer were 26% and 20% respectively. Among the 5 responding patients with cervical cancer, and as of a median follow-up of 19.2 months, the median duration of response has not been reached. (2)