- Design
- Phase 3, randomised, double-blind, placebo-controlled, three-arm trial
- Population
- 1,367 women with stage III-IV BRCA non-mutated epithelial ovarian cancer
- Primary outcome
- Progression-free survival (CPS 10 or more, then ITT)
- Effect
- Pembrolizumab-olaparib vs control: ITT HR 0.71 (0.61-0.84)
KEYLYNK-001, published in Lancet Oncology on 7 September 2026, randomised 1,367 women with stage III-IV epithelial ovarian, peritoneal or fallopian tube cancer without BRCA mutation to chemotherapy plus pembrolizumab followed by pembrolizumab-olaparib maintenance, chemotherapy plus pembrolizumab followed by pembrolizumab alone, or chemotherapy and placebo.
At final analysis, with median follow-up of about 50 months, pembrolizumab-olaparib improved progression-free survival against control in the PD-L1 CPS 10 or more group (HR 0.66, 95% CI 0.53 to 0.83) and in all patients (HR 0.71, 0.61 to 0.84). Pembrolizumab without olaparib did not improve progression-free survival (HR 0.95). Grade 3 or worse treatment-related events occurred in 66% against 51%, serious treatment-related events in 24% against 9%, and four treatment-related deaths in the combination arm.
The benefit appears to come from adding olaparib rather than from pembrolizumab alone. Without overall survival data and with substantially more serious toxicity, the regimen's place in first-line care is not settled.
- Recognise that pembrolizumab alone added nothing to progression-free survival in this population.
- Weigh the progression-free gain against a near threefold rise in serious treatment-related events.
- Test BRCA and homologous recombination status at diagnosis to guide maintenance choice.
- Await overall survival before treating this as a new standard.
Why it matters
It suggests PARP inhibition contributes in BRCA non-mutated disease, while immunotherapy alone does not.
Don't overread it
Progression-free survival only; no overall survival benefit has been shown.
The statistics, in plain English
The hazard ratio of 0.71 for all patients means about 29% lower risk of progression. Pembrolizumab alone had a hazard ratio of 0.95 with an interval crossing 1, so no benefit.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for oncology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free