NEW YORK – New data from the SOLO-1 trial presented at a conference this week demonstrate that first-line maintenance treatment with the PARP inhibitor olaparib (AstraZeneca/Merck's Lynparza) results in a sustained progression-free survival benefit for patients with BRCA-mutated advanced ovarian cancer.
Nearly two years ago, the US Food and Drug Administration approved the PARP inhibitor olaparib (AstraZeneca/Merck's Lynparza) as first-line maintenance therapy for patients with advanced ovarian cancer harboring BRCA1 or BRCA2 mutations following treatment with platinum-based chemotherapy.
"After five years' follow-up, results of the SOLO-1 trial represent the longest follow-up that we've seen with any PARP inhibitor in this setting," Susana Banerjee of the Royal Marsden NHS Foundation Trust in the UK, said in a presentation of the data during the European Society for Medical Oncology's Virtual Congress on Friday.
In the Phase III SOLO-1 trial, 391 patients with advanced, BRCA-mutated ovarian cancer who had complete or partial responses to chemotherapy were randomized to receive either olaparib or a placebo for two years. Five years after the final study participant was randomized, 48.3 percent of patients treated with olaparib remained disease-free compared with 20.5 percent of patients in the control arm. The median progression-free survival on the PARP inhibitor was 56 months versus 13.8 months on the placebo, translating to 3.5 years of additional disease-free survival for those treated with the PARP inhibitor.
"The substantial benefits of maintenance olaparib continued beyond the end of treatment," said Banerjee, highlighting the fact that even though the median duration of olaparib treatment was only a little over two years, patients on average continued to live without cancer progression for years after stopping treatment, since the median progression-free survival was nearly 4.5 years.
In addition to the overall five-year follow-up, SOLO-1 investigators performed a post-hoc analysis of a subgroup of patients who achieved a complete response to platinum-based chemotherapy at baseline. In these patients, 52 percent treated with olaparib remained free from relapse after five years, compared to 22 percent in the placebo arm.
No new safety signals were observed in the long-term follow-up, and according to Banerjee, "these results provide further evidence to support the use of maintenance olaparib as a standard of care for women with newly-diagnosed, BRCA-mutated advanced ovarian cancer. It raises the possibility of achieving long-term remission and even cure for some patients."
"Today's results further underline the critical importance of identifying a patient's biomarker status at the time of diagnosis to be able to offer a maintenance treatment that may help delay disease progression for these patients," José Baselga, AstraZeneca's executive VP of oncology R&D, said in a statement about the results. The 2018 FDA approval based on the SOLO-1 trial indicated that Myriad Genetics' BRACAnalysis CDx would be used to determine patients' eligibility for the first-line maintenance therapy.
Of note, olaparib is also approved as maintenance therapy in recurrent ovarian cancer regardless of BRCA mutation status, but for many oncologists, patients' biomarker status remains a key consideration, as data continue to show more pronounced responses in the biomarker-defined patient population.