Neoadjuvant niraparib alone in HRD-positive ovarian cancer: 63% response, 80% R0

Design

Single-arm, multicentre, phase 2 trial

Population

67 women with HRD-positive stage III-IV high-grade ovarian cancer unsuitable for primary surgery

Primary outcome

Objective response rate and R0 resection rate

Effect

ORR 63% (95% CI 47-76); R0 80% (64-91) of 40 operated

NANT was a single-arm phase 2 trial at six Chinese hospitals. It enrolled 67 women with treatment-naive stage III to IV high-grade serous or endometrioid ovarian cancer that was positive for homologous recombination deficiency and judged unlikely to be fully debulked at primary surgery. They received two 28-day cycles of oral niraparib, 200 or 300 mg, instead of neoadjuvant chemotherapy.

Of 48 evaluable patients, 63% responded (95% CI 47 to 76). Of 40 who went on to interval surgery, 80% had no residual disease (95% CI 64 to 91). Grade 3 to 4 thrombocytopenia occurred in 48%, leukopenia in 19% and anaemia in 18%; there were no treatment-related deaths.

A chemotherapy-free start is attractive for women who are frail or reluctant to begin with platinum and taxane. But this is a single-arm study without a comparison, and the authors themselves describe it as investigational. Neoadjuvant platinum-taxane chemotherapy remains the standard; the result calls for a randomised trial, not a change in practice.

• Neoadjuvant platinum-taxane chemotherapy remains standard for advanced ovarian cancer unsuitable for primary surgery.
• HRD testing at diagnosis is needed to identify who might benefit from PARP-based strategies.
• Expect substantial thrombocytopenia with niraparib; nearly half had grade 3 to 4.
• Consider trial referral for women interested in a chemotherapy-free approach.

Why it matters

It suggests a PARP inhibitor alone can shrink HRD-positive disease enough to operate, which raises the question of whether chemotherapy must always come first.

Don't overread it

Single-arm phase 2; without a chemotherapy comparator it cannot show niraparib is as good.

The statistics, in plain English

With 48 evaluable patients the response rate's confidence interval runs from 47% to 76%, so the true rate could be similar to what chemotherapy achieves or better. Single-arm trials also select fitter patients, which flatters results.

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