A study presented at the virtual 2021 Society of Gynecologic Oncology (SGO) Annual Meeting on Women’s Cancer compared the tolerability and dose modifications of PARP inhibitor therapies for ovarian cancer in the United States.

“Three PARP inhibitors are approved for maintenance therapy and as treatment of ovarian cancer, however, real-world evidence focusing on comparative tolerability and dose modifications is lacking,” explained Rebecca Arend, MD, University of Alabama, Birmingham, during her presentation.

This study aimed to characterize the real-world tolerability of PARP inhibitors, in terms of clinical events of interest and dose modifications, in the United States.

MarketScan Commercial and Medicare Supplemental Databases were used to identify patients with ovarian cancer who initiated olaparib, niraparib, or rucaparib between January 1, 2017, and May 31, 2019. In addition, 16 predefined clinical events of interest were identified from claims data based on ICD 9/10 code criteria.

A total of 813 patients were included in the study; 303 received olaparib, 348 received niraparib, and 162 received rucaparib.

In patients with ovarian cancer who received a PARP inhibitor, the risk of experiencing any clinical event of interest was higher in niraparib vs olaparib (OR, 3.36 [95% CI, 2-5.65]) and with niraparib vs rucaparib (OR, 2.09 [95% CI 1.1-3.95]). The difference between rucaparib and olaparib was not statistically significant.

Differences were also observed between the licensed PARP inhibitors in the likelihood of dose modifications and the ability to receive continuous therapy.

Overall, 89.4%, 69.3%, and 93.2% of patients receiving olaparib, niraparib, and rucaparib, respectively, started at the highest indicated dose. Dose decreases were the most common dose adjustment and were observed in 21.1%, 35.1%, and 30.2% of patients receiving olaparib, niraparib, and rucaparib, respectively.

In a subgroup analysis of patients with ≥6 months of medical claims data following PARP inhibitor initiation, the proportion of patients with treatment persistence (no treatment gaps >90 days) were 62.2% (107 of 172 patients) with olaparib, 25.9% (90 of 251 patients) with niraparib, and 48.7% (57 of 117 patients) with rucaparib. The proportion of patients adherent to treatment were 80.2%, 38.6%, and 63.2%, respectively.

“To our knowledge this is the largest real-world comparison of PARP inhibitor therapy in women with ovarian cancer. Further research is required to assess the influence of medication adherence on long-term effectiveness and how best to support patients receiving PARP inhibitors,” Dr Arend concluded.—Janelle Bradley