Trial’s Long-Term Follow-Up Data Shows No Difference in Overall Survival Among Ovarian Cancer Patients Who Did and Did Not Receive Parp Inhibitor Maintenance Therapy

(Sunday, March 26, 2023) – After resolving missing data burdens, the ENGOT-OV16/NOVA (NCT01847274) study data shows no difference in overall survival for platinum-sensitive recurrent ovarian cancer (PSROC) patients who received PARP inhibitor niraparib maintenance therapy (MT) and those who did not. Results from the trial were presented today at the Society of Gynecologic Oncology (SGO) 2023 Annual Meeting on Women’s Cancer by Ursula Matulonis, MD, of the Dana-Farber Cancer Institute.

ENGOT-OV16/NOVA was a randomized, double-blind, placebo-controlled, phase three trial. There were 553 total PSROC patients in the study, and they were enrolled into independent germline BRCA (gBRCAm) and non-gBRCA cohorts, then randomized two to one to receive niraparib 300 mg once daily or placebo.

Primary results from the study, released in 2016 in the New England Journal of Medicine, indicated progression free survival benefit of niraparib MT compared to placebo MT. The initial overall survival (OS) analysis was presented at the 2021 SGO annual meeting, but the survival analysis, the researchers’ secondary endpoint, was limited by missing follow-up survival data on 92 patients.

Survival status is now available for 97.6 percent of patients for this updated analysis. However, survival data is challenging to interpret.

“There are imbalances in post-progression therapy in the different groups, and missing data still exists on these post-progression therapies,” said Matulonis. “And, the study was not powered for formal overall survival analyses, creating additional interpretation challenges.” 

Once data was resolved, the survival differences between the niraparib and placebo arms were not interpreted to be significant in either cohort, though the overall survival hazard ratio numerically favored niraparib in the gBRCAm cohort and favored placebo in the non-gBRCA cohort.

In addition, no new safety signals were observed with long-term follow-up. As of the March 31, 2021 data cutoff, 3.8 percent of patients who received niraparib and 1.7 percent of patients who received placebo developed myelodysplastic syndrome or acute myeloid leukemia (MDS/AML). The risk of MDS/AML was highest in the gBRCAm patients treated with a PARP inhibitor and was 7.4%, consistent with other phase III studies in the recurrent platinum-sensitive setting. 

The results of the trial underscore the importance of long-term follow-up of patients and also point to a continued need for research.

"Our patients with ovarian cancer are living longer and are thus receiving more therapies,” said Matulonis. “It is critical for trials to follow patients long-term for overall survival after they stop study treatment and to carefully record and chronicle post-study treatment therapies. Understanding the impact of PARP inhibitor therapy on post-progression treatment resistance is also an important area of research.” 

About SGO
The Society of Gynecologic Oncology (SGO) is the premier medical specialty society for health care professionals trained in the comprehensive management of gynecologic cancers. As a 501(c)(6) organization, SGO contributes to the advancement of gyn cancer care by encouraging research, providing education, raising standards of practice, advocating for patients and members and collaborating with other domestic and international organizations. Learn more at www.sgo.org.