The SOLO1 trial evaluated the efficacy of olaparib as maintenance therapy in patients with newly diagnosed advanced ovarian cancer and a BRCA1/2 mutation. The study involved 391 patients randomized to receive olaparib (300 mg twice daily) or placebo. After a median follow-up of 41 months, olaparib significantly reduced the risk of disease progression or death compared to placebo, with a 70% lower risk (hazard ratio 0.30; 95% CI 0.23–0.41; P<0.001). The 3-year progression-free survival rate was 60% in the olaparib group versus 27% in the placebo group. The median progression-free survival was 13.8 months in the placebo group and 24.1 months in the olaparib group. The trial also showed a significant improvement in second progression-free survival and overall survival. Adverse events were consistent with the known toxic effects of olaparib, with anemia being the most common serious adverse event. The safety profile of olaparib was generally acceptable, with low rates of dose reduction or discontinuation. The results support the use of olaparib as maintenance therapy in patients with newly diagnosed advanced ovarian cancer and a BRCA1/2 mutation, providing substantial benefit in progression-free survival. The trial was funded by AstraZeneca and Merck.The SOLO1 trial evaluated the efficacy of olaparib as maintenance therapy in patients with newly diagnosed advanced ovarian cancer and a BRCA1/2 mutation. The study involved 391 patients randomized to receive olaparib (300 mg twice daily) or placebo. After a median follow-up of 41 months, olaparib significantly reduced the risk of disease progression or death compared to placebo, with a 70% lower risk (hazard ratio 0.30; 95% CI 0.23–0.41; P<0.001). The 3-year progression-free survival rate was 60% in the olaparib group versus 27% in the placebo group. The median progression-free survival was 13.8 months in the placebo group and 24.1 months in the olaparib group. The trial also showed a significant improvement in second progression-free survival and overall survival. Adverse events were consistent with the known toxic effects of olaparib, with anemia being the most common serious adverse event. The safety profile of olaparib was generally acceptable, with low rates of dose reduction or discontinuation. The results support the use of olaparib as maintenance therapy in patients with newly diagnosed advanced ovarian cancer and a BRCA1/2 mutation, providing substantial benefit in progression-free survival. The trial was funded by AstraZeneca and Merck.