Estimating long-term overall survival with olaparib as maintenance therapy in patients with newly diagnosed advanced ovarian cancer with BRCA mutations

Background. According to randomized clinical trial SOLO1 olaparib statistically significantly improves progression-free survival versus placebo as a maintenance monotherapy in patients aged 18 and over with newly diagnosed advanced ovarian cancer with BRCA mutations, who had response to first-line chemotherapy. As the data on overall survival (OS) in this trial remains interim it is still uncertain whether treatment with olaparib can provide any benefits in terms of OS.

Objective: to evaluate a long-term OS for olaparib versus placebo as a maintenance monotherapy in patients with newly diagnosed advanced ovarian cancer with BRCA mutations, who had response to first-line chemotherapy.

Materials and methods. A 10-year mathematic model of disease progression and survival on olaparib versus placebo was developed. Modelling was based on data on progression-free survival from SOLO1 trial and data on OS after platinum-sensitive and platinum-resistant relapses from OCEANS and AURELIA trials. Additionally, patients who haven’t been treated with olaparib after first-line therapy in base-case scenario were assumed to get olaparib as a second-line treatment after platinum-sensitive relapse; mortality modelling for these patients was based on data from SOLO2 trial.

Results. Median OS for olaparib was 107 months versus 66 months for placebo. 46 % of patients treated with olaparib were alive by the end of 10-year modelling period, but only 28 % patients from the placebo group. Hazard ratio of death for olaparib versus placebo was 0.64 (95 % confidence interval 0.49–0.84). Probabilistic sensitivity analysis showed robustness of these results.

Conclusion. Using olaparib as a maintenance therapy in patients with newly diagnosed advanced ovarian cancer with BRCA mutations, who had response on first line chemotherapy, statistically significantly reduces risk of death by 36 %, compared to placebo.

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