The following article features coverage from the American Society of Clinical Oncology 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Final results from the phase 2 KEYNOTE-100 trial confirm that single-agent pembrolizumab had modest antitumor activity in patients with recurrent advanced ovarian cancer, according to results presented during the ASCO20 Virtual Scientific Program.

Patients with higher PD-L1 expression appeared to have better overall response rates, according to Ursula Matulonis, MD, of Dana-Farber Cancer Institute in Boston, Massachusetts, who presented the results.

According to her presentation, results from KEYNOTE-028 (ClinicalTrials.gov Identifier: NCT02054806) showed that pembrolizumab resulted in an overall response rate of 11.5% in patients with PD-L1 positive recurrent ovarian cancer. These results prompted initiation of KEYNOTE-100 (ClinicalTrials.gov Identifier: NCT02674061).

The study enrolled patients with epithelial, fallopian tube, or primary peritoneal cancer with confirmed recurrence after front-line platinum-based therapy. Cohort A (285 patients) had received 2 or fewer prior lines of therapy and had a platinum-free or treatment-free interval of at least 3 months. Cohort B (91 patients) had received 3 to 5 prior lines of therapy and had a platinum-free or treatment-free interval of at least 3 months.


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All patients received pembrolizumab 200 mg every 3 weeks for 2 years or until progression, death, or unacceptable toxicity.

An interim analysis of KEYNOTE-100 showed modest clinical activity in patients with recurrent advanced ovarian cancer after a follow-up of 18.3 months. The overall response rate was 8.0% at that time.

At the final analysis with a median follow-up of 37.8 months, the overall response rate was 8.1% in cohort A and 9.9% in cohort B. For both cohorts combined, the overall response rate was 8.5%.

Among patients with combined positive score of 10 or greater, the overall response rate was 11.6% in cohort A and 18.2% in cohort B. For cohorts A and B combined, those with higher PD-L1 expression had an overall response rate of 13.8%.

The median duration of response was 8.3 months in cohort A and 23.6 months in cohort B. For all-comers, the median duration of response was 10.2 months. According to Dr Matulonis, 67.7% of responses lasted 6 months or longer. Median progression-free survival was 2.1 months in both cohorts.

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Overall survival was 18.7 months in cohort A and 17.6 months in cohort B. Among patients with higher PD-L1 expression, overall survival was 21.9 months in cohort A and 24.0 months in cohort B.

About 5% of patients discontinued treatment because of treatment-related adverse events. The researchers reported 2 treatment-related deaths. Immune-mediated adverse events occurred in 23.7% of patients.

Read more of Cancer Therapy Advisor‘s coverage of the ASCO 2020 meeting by visiting the conference page.

Reference

Matulonis UA, Shapira R, Santin A, et al. Final results from the KEYNOTE-100 trial of pembrolizumab in patients with advanced recurrent ovarian cancer. Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr 6005.