Pembrolizumab with olaparib maintenance lengthened progression-free survival in BRCA-negative ovarian cancer

Design

Phase 3, randomised 1:1:1, double-blind, placebo-controlled

Population

1,367 women with stage III–IV BRCA-non-mutated epithelial ovarian cancer

Primary outcome

Progression-free survival (CPS ≥10, then ITT)

Effect

Pembrolizumab–olaparib vs control: HR 0.66 (CPS ≥10), 0.71 (ITT); pembrolizumab alone HR 0.95

KEYLYNK-001 randomised 1,367 women with newly diagnosed stage III–IV epithelial ovarian cancer without a BRCA mutation, after one lead-in chemotherapy cycle, to three arms: pembrolizumab with chemotherapy then pembrolizumab plus olaparib maintenance; pembrolizumab with chemotherapy then pembrolizumab maintenance; or chemotherapy alone with placebo. Bevacizumab was allowed. It was published on 7 September.

At final analysis, with median follow-up about 50 months, pembrolizumab plus olaparib improved progression-free survival against chemotherapy alone in the PD-L1 CPS ≥10 group (HR 0.66, 95% CI 0.53–0.83) and in everyone randomised (HR 0.71, 0.61–0.84). Pembrolizumab without olaparib did not (HR 0.95 in CPS ≥10). Grade 3 or higher treatment-related adverse events occurred in 66% with the combination against 51% with chemotherapy, serious ones in 24% against 9%, and four treatment-related deaths occurred with the combination.

The benefit appears to come from adding olaparib to maintenance, since pembrolizumab alone added nothing measurable. Overall survival is not reported here, and the toxicity cost is substantial. In India, both drugs are expensive and this combination is not an established standard; any adoption would depend on survival data, regulatory approval and cost.

• Do not add pembrolizumab alone to first-line chemotherapy in BRCA-negative ovarian cancer; it showed no benefit.
• Discuss that the pembrolizumab–olaparib combination improved progression-free survival but not yet shown overall survival.
• Weigh the higher rate of serious adverse events, including anaemia and febrile neutropenia, against the benefit.
• Check HRD and BRCA status at diagnosis, as they shape maintenance choices.

Why it matters

It suggests the gain lies with the PARP inhibitor, not the immunotherapy, in BRCA-negative disease.

Don't overread it

Progression-free survival is not overall survival, and no survival benefit is reported.

The statistics, in plain English

A hazard ratio of 0.71 means about 29% lower risk of progression or death at any point. Hierarchical testing means pembrolizumab alone was formally tested only in the CPS ≥10 group, where it failed, so no claim can be made for it in anyone.

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