CHICAGO—Pembrolizumab is well-tolerated and shows promising antitumor activity and early survival rates among patients with PD-L1–positive cervical squamous cell cancer, according to preliminary results from the phase Ib KEYNOTE-028 trial, presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 3–7 (abstract 5515).
“Pembrolizumab had durable antitumor activity in patients with PD-L1–positive advanced cervical cancer,” said lead study author Jean-Sébastien Frenel, MD, of the Institut de Cancérologie in Saint-Herblain, France. “Responses lasted for a median of 26 weeks with some extending to 1 year.”
Median progression-free survival was 2 months, and the 6-month and 12-month progression-free survival rates were 21% and 8%, respectively. Overall survival was promising, Dr. Frenel reported. The median overall survival was 9 months (range, 4–12 months). The 6-month overall survival rate was 67%, and the 12-month overall survival rate was 33%.
Combination therapy with chemotherapy and bevacizumab is an approved first-line treatment for advanced cervical cancer, but additional effective treatment options for advanced cervical cancer are urgently needed, particularly for patients whose cancer progresses on first-line therapy. “Many patients are platinum-resistant,” Frenel noted.
Twenty-four patients with metastatic or unresectable, PD-L1–positive cervical cancer that had failed (or who were unable to receive) standard chemotherapy were administered pembrolizumab (10 mg/kg intravenously, every 2 weeks). Response was assessed every 8 weeks for the first 6 months, and then every 12 weeks. Patients with complete or partial responses, or stable disease, were treated for 24 months or until progression or intolerable toxicity. Patients who experienced disease progression or who did not tolerate toxicity discontinued pembrolizumab.
No patients experienced complete responses upon investigator review using RECIST v1.1 criteria. Four of 23 evaluable patients experienced partial responses, three had stable disease and 16 had disease progression.
The safety profile was in line with previous reports for pembrolizumab in other cancer types. Two patients discontinued treatment following grade 3 treatment-related adverse events. No patient deaths or grade 4 treatment-related adverse events were reported.
The clinical benefit and safety of pembrolizumab in advanced cervical cancer will undergo additional study in the currently enrolling phase II KEYNOTE-158 trial (NCT02628067).