Keytruda Improves Survival in Platinum-Resistant Ovarian Cancer

Merck announced that the phase 3 KEYNOTE-B96 trial showed Keytruda (pembrolizumab) plus paclitaxel with or without bevacizumab significantly improved overall survival for patients with platinum-resistant recurrent ovarian cancer compared with paclitaxel with or without bevacizumab alone, offering a new option for patients whose disease has progressed after prior treatment.

Results from the final analysis will be presented during a Best Oral Session at the European Society of Gynaecological Oncology 2026 Congress. According to the company, this marks the first PD-1 inhibitor–based regimen to demonstrate a statistically significant improvement in overall survival regardless of PD-L1 status in this setting.

The findings build on earlier data from the trial, which previously met its primary endpoint of progression-free survival in the overall study population and in patients whose tumors express PD-L1 with a Combined Positive Score of 1 or higher. The regimen also met a key secondary endpoint of overall survival in patients whose tumors express PD-L1 (CPS greater than or equal to 1).

Main data show reduced risk of death and disease progression

At the final analysis, after a median follow-up of 32.7 months (range, 26.1-44.1), patients who received Keytruda plus paclitaxel with or without bevacizumab experienced a statistically significant and clinically meaningful improvement in overall survival compared with those who received paclitaxel with or without bevacizumab alone.

In the all comers population, the Keytruda regimen reduced the risk of death by 18% compared with paclitaxel with or without bevacizumab alone. Median overall survival was 17.7 months for patients who received the Keytruda combination compared with 14.0 months for those who received the placebo regimen.

The regimen also reduced the risk of disease progression or death by 27% in the overall study population.

Among patients whose tumors express PD-L1 (CPS greater than or equal to 1), the Keytruda regimen reduced the risk of disease progression or death by 24% compared with paclitaxel with or without bevacizumab alone. In this same group, the regimen reduced the risk of death by 24%.

Merck noted that the observed overall survival is among the longest reported in any clinical trial for platinum-resistant recurrent ovarian cancer relative to the most active standard of care control arm, which included weekly paclitaxel with bevacizumab in bevacizumab-eligible patients.

In addition to the clinical results, the European Medicines Agency’s Committee for Medicinal Products for Human Use adopted a positive opinion recommending approval of Keytruda in combination with paclitaxel with or without bevacizumab for certain adults with PD-L1 (CPS greater than or equal to 1) platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma who have received one or two prior systemic treatment regimens.

In February, the U.S. Food and Drug Administration approved Keytruda plus paclitaxel with or without bevacizumab for adult patients with platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal carcinoma whose tumors express PD-L1 (CPS greater than or equal to 1), as determined by an FDA-authorized test, and who have received one or two prior systemic treatment regimens.

Trial details: phase 3 KEYNOTE-B96 design and patient population

KEYNOTE-B96, also known as ENGOT-ov65, is a multicenter, randomized, double-blind, placebo-controlled phase 3 trial sponsored by Merck and conducted in collaboration with European Network for Gynecologic Oncology Trial groups.

The trial enrolled 643 patients with epithelial ovarian, fallopian tube or primary peritoneal carcinoma whose disease was platinum-resistant and recurrent. Patients had received one or two prior lines of systemic therapy, including at least one line of platinum-based chemotherapy. Enrollment was open regardless of PD-L1 tumor expression status. Of the 643 enrolled patients, 72% had tumors expressing PD-L1 (CPS greater than or equal to 1).

Patients were randomly assigned in a 1:1 ratio to receive either Keytruda plus paclitaxel with or without bevacizumab or placebo plus paclitaxel with or without bevacizumab.

Keytruda at 400 milligrams (mg) or placebo was administered on Day 1 of each six-week treatment cycle. Paclitaxel at 80 mg/m2 was given on Days 1, 8 and 15 of each three-week treatment cycle. The use of bevacizumab was determined by the investigator before randomization. When used, bevacizumab at 10 mg/kg was administered on Day 1 of a two-week treatment cycle.

The primary endpoint of the study was progression-free survival. Overall survival was a key secondary endpoint.

Safety profile and reported side effects

The safety profile of Keytruda in this trial was consistent with previously reported studies, and no new safety concerns were identified.

Grade 3 (severe) or higher treatment-related side effects occurred in 67.8% of patients receiving the Keytruda regimen (320 patients) compared with 55.3% of patients receiving the placebo regimen (318 patients). Treatment-related side effects led to death in 1.3% of patients in the Keytruda arm and 1.6% of patients in the placebo arm.

Immune-mediated side effects and infusion reactions of any grade occurred in 39.4% of patients receiving the Keytruda regimen and 18.9% of patients receiving the placebo regimen. The most common immune-mediated side effect occurring in at least 10% of patients receiving the Keytruda regimen was hypothyroidism, reported in 18.1% of patients.

Immune-mediated side effects led to death in 0.6% of patients in the Keytruda arm and in no patients in the placebo arm.

References

1. “KEYTRUDA® (pembrolizumab) Plus Paclitaxel With or Without Bevacizumab Significantly Improved Key Secondary Endpoint of Overall Survival (OS) Versus Paclitaxel With or Without Bevacizumab in Patients With Platinum-Resistant Recurrent Ovarian Cancer” by Dr. Nicoletta Colombo, et al., presented at the European Society of Gynaecological Oncology 2026 Congress.

Editor's note: This article is for informational purposes only and is not a substitute for professional medical advice, as your own experience will be unique. Use this article to guide discussions with your oncologist. Content was generated with AI, reviewed by a human editor, but not independently verified by a medical professional.

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