Maintenance treatment with niraparib may provide a lasting benefit in patients with ovarian cancer, according to a presentation at the European Society for Medical Oncology (ESMO) Gynaecological Cancers Virtual Congress 2021.1

Updated phase 3 data showed a second progression-free survival (PFS2) benefit in certain patients who received niraparib, but there was no overall survival (OS) benefit with niraparib.

“Final PFS2 analysis indicated that the benefit of niraparib maintenance therapy extended beyond first progression, but overall survival data is challenging to interpret,” said Mansoor Raza Mirza, MD, of Copenhagen University Hospital in Denmark, who presented the data at the congress.

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The phase 3 ENGOT-OV16/NOVA trial ( Identifier: NCT01847274) enrolled patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who had achieved a partial or complete response with prior platinum-based chemotherapy.

There were 203 patients with germline BRCA mutations who were randomly assigned to maintenance with niraparib (n=138) or placebo (n=65) and 350 patients without such mutations who were randomly assigned to niraparib (n=234) or placebo (n=116) maintenance. 

The initial PFS results were published in 2016.2 In the BRCA-mutant group, the median PFS was 21.0 months with niraparib and 5.5 months with placebo (hazard ratio [HR], 0.27; 95% CI, 0.17-0.41; P <.001). In the group without BRCA mutations, the median PFS was 9.3 months and 3.9 months, respectively (HR, 0.45; 95% CI, 0.34-0.61; P <.001).

In the final analysis, PFS2 was significantly longer with niraparib than with placebo among patients with BRCA mutations (HR, 0.67; 95% CI, 0.479-0.948). There was a trend toward improved PFS2 with niraparib in patients without BRCA mutations, but this was not significant (HR, 0.81; 95% CI, 0.632-1.050).

At the final OS analysis, the average follow-up was 5.6 years, and there was no difference in OS between the niraparib and placebo groups.

In patients without BRCA mutations, the median OS was 31.1 months with niraparib and 36.5 months with placebo (HR, 1.10; 95% CI, 0.831-1.459). In patients with BRCA mutations, the median OS was 43.6 months and 41.6 months, respectively (HR, 0.93; 95% CI, 0.633-1.355).

Dr Mirza noted that the trial was not statistically powered for OS, and the analysis was hindered by a high rate of study withdrawal, subsequent PARP inhibitor use, and missing data.

Hematologic treatment-emergent adverse events of grade 3 or higher occurred most frequently during the first year of treatment with niraparib and decreased substantially during years 2-3, Dr Mirza reported.

There were 13 cases of myelodysplastic syndromes/acute myeloid leukemia in the niraparib arm and 3 cases in the placebo arm.

Disclosures: This research was supported by Tesaro, Inc., Myriad Genetics, Inc., and others. Dr Mirza declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


  1. Mirza MR. Long-term safety and secondary efficacy endpoints in the ENGOT-OV16/NOVA phase 3 trial on niraparib in recurrent ovarian cancer. Presented at: ESMO Gynaecological Cancers Virtual Congress; June 25-26, 2021.
  2. Mirza MR, Monk BJ, Herrstedt J, et al. Niraparib maintenance therapy in platinum-sensitive, recurrent ovarian cancer. N Engl J Med. 2016; 375:2154-2164. doi:10.1056/NEJMoa1611310