The progression-free survival (PFS) benefit observed with olaparib maintenance persists after treatment completion in patients with advanced ovarian cancer, according to research published in The Lancet Oncology.

Five-year follow-up data from the phase 3 SOLO1 trial showed a sustained PFS benefit with 2 years of olaparib maintenance, compared with placebo, in patients with ovarian cancer.

“To our knowledge, this report represents the longest follow-up period for a PARP inhibitor in the newly diagnosed advanced ovarian cancer setting and the first demonstration of a progression-free survival benefit with a PARP inhibitor as maintenance monotherapy that extends beyond completion of treatment,” the researchers wrote.


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SOLO1 (ClinicalTrials.gov Identifier: NCT01844986) was a randomized, double-blind, phase 3 trial that included 391 patients with BRCA-mutated, newly diagnosed, advanced, high-grade serous or endometrioid ovarian cancer who responded to platinum-based chemotherapy.

Patients were randomly assigned to receive oral olaparib (260 patients) or placebo (130 patients) as maintenance therapy for up to 2 years.

The median duration of treatment was 24.6 months in the olaparib arm and 13.9 months in the placebo arm. The median follow-up for PFS was 4.8 years and 5.0 years, respectively. 

The median PFS was 56.0 months with olaparib and 13.8 months with placebo (hazard ratio [HR], 0.33; 95% CI, 0.25-0.43). The 5-year PFS rate was 48% and 21%, respectively.

The PFS benefit with olaparib was seen whether patients had a BRCA1 or BRCA2 mutation and whether they had high or low clinical risk.

Among patients in the higher-risk group, the median PFS was 40.6 months in the olaparib arm and 11.1 months in the placebo arm (HR, 0.34; 95% CI, 0.24-0.49). In the lower-risk group, the median PFS was not reached and 21.9 months, respectively (HR, 0.38; 95% CI, 0.25-0.59).

The most common grade 3-4 adverse events (in the olaparib and placebo arms, respectively) were anemia (22% vs 2%) and neutropenia (8% vs 5%).

Serious adverse events occurred in 21% of patients in the olaparib arm and 13% of patients in the placebo arm. There were no additional cases of myelodysplastic syndrome or acute myeloid leukemia reported and no new safety signals.

“Although overall survival data are not yet available, the 5-year follow-up results of the SOLO1 trial support the use of maintenance olaparib as a standard of care for women with newly diagnosed ovarian cancer and a BRCA mutation, and suggest that maintenance olaparib can provide long-term remission, and potentially cure, for some patients, so that their life expectancy could approach that of the age-adjusted general population,” the researchers wrote.

Disclosures: This research was supported by AstraZeneca and Merck Sharpe & Dohme. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Banerjee S, Moore KN, Colombo N, et al. Maintenance olaparib for patients with newly diagnosed advanced ovarian cancer and a BRCA mutation (SOLO1/GOG 3004): 5-year follow-up of a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet Oncol. Published online October 26, 2021. doi:10.1016/S1470-2045(21)00531-3