GSKBrentford, UK–headquartered GSK (LSE/NYSE:GSK) reported long-term data from the phase 3 PRIMA study indicating that the PARP inhibitor Zejula (niraparib) promoted a sustained and clinically meaningful progression-free survival (PFS) benefit in ovarian cancer patients.

The survival benefit was evident across biomarker subgroups, including BRCAm, HRd and HRp.

Patients in the HRd subgroup had a 48% reduction of progression or death compared to placebo.

The estimated probability of no progressive disease or death at four years in the broader population was 24% for niraparib compared to 14% for placebo.

GSK plans to present the updated efficacy analysis data on September 11 at the (European Society for Medical Oncology) ESMO Annual Meeting in Paris.

GSK noted in a news release that the overall survival data are “not yet mature based on the prespecified analysis plan.”

The study tested niraparib as maintenance therapy in first-line ovarian cancer patients who had a response to platinum-based chemotherapy.

Waltham, Massachusetts–based Tesaro initially developed niraparib, which won FDA approval for recurrent ovarian cancer in 2017. Niraparib was the first PARP inhibitor to win FDA approval without requiring BRCA mutation or another biomarker testing.

Niraparib won Fast Track designation for recurrent platinum-sensitive ovarian, fallopian tube, or primary peritoneal cancer in 2016.

GSK announced an agreement to acquire Tesaro in late 2018.

Niraparib has scored additional indications for ovarian cancer in 2019 and 2020.

“Patients can face a high risk of recurrence when diagnosed with late-stage ovarian cancer,” said Hesham Abdullah, senior vice president, global head of oncology development at GSK, in a news release. “The updated analysis of this study shows that Zejula can help patients potentially achieve a long-term remission.”

GSK noted that the study uncovered no new safety signals and that the safety profile of niraparib was in line with the primary analysis.

GSK shares were up 1% to $31.83 in early afternoon trading.