The invited discussant of the SOLO-1 trial, Deborah Armstrong, MD, Professor of Oncology and Director of the Breast and Ovarian Surveillance Service at Johns Hopkins Medicine, said the update provides “important information for us.” It shows that 2 years of maintenance olaparib conveys “a really profound difference” in outcomes after completion of primary therapy: a median progression-free survival of 56.0 months vs 13.8 months with placebo—a 67% risk reduction.

The benefit was significant regardless of baseline prognosis, with the time to second disease progression or death and the time to subsequent therapy showing “very tight” hazard ratios of 0.46 to 0.50, she pointed out. “Even patients with BRCA mutations who had suboptimal [debulking] or stage IV disease, or who received neoadjuvant therapy, maintained a significant benefit with the PARP inhibitor,” she observed.

“Also, of note, no new cases of hematologic malignancies were identified,” she added. In further discussion of this topic during the question-and-answer session, Dr. Armstrong suggested that BRCA mutation carriers may be the patients at highest risk for myelodysplastic syndrome or acute myeloid leukemia, as many had breast cancer before and were treated with alkylating agents. “Trials did not exclude these patients, and their risk may be quite a bit higher,” she commented.

Duration of Maintenance Therapy

Another question arose regarding the optimal duration of maintenance therapy. Dr. Armstrong said she treats according to trial design: 2 years with olaparib and 3 years with niraparib. Dr. Bradley agreed: “Off trial, I think we have to stick with 2 years at this point.” 

DISCLOSURE: Dr. Armstrong has served as a consultant or advisor to AbbVie and Eisai; has received institutional research funding from AstraZeneca, Clovis Oncology, Eisai, Pfizer, and Syndax; and has held other relationships with AstraZeneca.