Pembrolizumab plus olaparib maintenance improved progression-free survival in BRCA non-mutated ovarian cancer

Design

Phase 3, randomised, double-blind, placebo-controlled, three-arm trial

Population

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

Primary outcome

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

Effect

Pembrolizumab–olaparib vs control: ITT HR 0.71 (95% CI 0.61–0.84) at final analysis

KEYLYNK-001, a double-blind phase 3 trial at 224 centres in 22 countries, randomised 1,367 women with newly diagnosed stage III–IV epithelial ovarian, peritoneal or fallopian tube cancer without a BRCA mutation. Arms were chemotherapy plus pembrolizumab then pembrolizumab–olaparib maintenance; chemotherapy plus pembrolizumab then pembrolizumab alone; or chemotherapy with placebo. Bevacizumab was allowed.

At final analysis (median follow-up 49.6 months), progression-free survival with pembrolizumab–olaparib remained better than control: HR 0.66 (95% CI 0.53–0.83) in those with PD-L1 CPS ≥10 and 0.71 (0.61–0.84) overall. Pembrolizumab without olaparib did not improve progression-free survival (HR 0.95 in CPS ≥10). Grade 3 or higher treatment-related adverse events occurred in 66% vs 51%, serious treatment-related events in 24% vs 9%, and four treatment-related deaths in the triplet arm.

The benefit appears to depend on olaparib; pembrolizumab alone added nothing. Overall survival is not reported in this abstract, and toxicity and cost are substantial. For BRCA non-mutated disease, this is one more maintenance option, not yet a clear new standard.

• Test every advanced epithelial ovarian cancer for BRCA and homologous recombination status to guide maintenance choice.
• Pembrolizumab added to chemotherapy without olaparib did not improve progression-free survival.
• Weigh a roughly 30% reduction in progression risk against double the rate of serious treatment-related events.
• Overall survival data are not yet shown; discuss this uncertainty with patients.
• Monitor for anaemia and neutropenia closely on combined pembrolizumab–olaparib maintenance.

Why it matters

It suggests PARP inhibitor benefit in BRCA non-mutated disease may be extended by adding immunotherapy, but only with olaparib present.

Don't overread it

Progression-free survival is a surrogate here; overall survival is not reported, and the trial was industry-funded.

The statistics, in plain English

A hazard ratio of 0.71 means about 29% lower risk of progression or death at any time. Progression-free survival does not always translate into longer life, which is why overall survival matters before calling this a new standard. Hierarchical testing means the pembrolizumab-alone arm could not be formally tested in everyone once it failed in the CPS ≥10 group.

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