Pembrolizumab Shows Durable Response in Advanced Unresectable Anal Cancer

Van K. Morris, MD, assistant professor in the Department of Gastrointestinal Medical Oncology at The University of Texas MD Anderson Cancer Center, discusses the findings of the KEYNOTE-158 trial (NCT02628067), which evaluated pembrolizumab (Keytruda) in advanced solid tumors in relation to patients with advanced unresectable anal cancer.

This study was the largest study so far using single-agent pembrolizumab as treatment that included this patient population. Investigators found that about 11% of patients responded to pembrolizumab monotherapy, which is similar to the results of a phase 2 NCI9673 trial (NCT02314169) published 3 years ago, according to Morris; this study looked at single-agent nivolumab (Opdivo) in patients with previously untreated unresectable metastatic anal cancer.

The patients who responded demonstrated durable responses and tolerated pembrolizumab and nivolumab well overall in these 2 studies. The KEYNOTE-158 trial categorized patients by PD-L1 expression status; patients’ tumors were considered PD-L1 high or PD-L1 low. There was no difference in response rates detected based on PD-L1 expression status, but Morris says there was a trend towards an increased likelihood for response in the patients who had tumors with PD-L1 expression.

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