NEW YORK – AstraZeneca and Merck said on Thursday that China's National Medical Products Administration has granted conditional approval to their PARP inhibitor olaparib (Lynparza) for patients with germline or somatic BRCA1- or BRCA2-mutated metastatic castration-resistant prostate cancer who have progressed after hormonal treatment with enzalutamide (Pfizer/Astellas' Xtandi) or abiraterone (Janssen's Zytiga).
The conditional approval is based on a subgroup analysis from the Phase III PROfound trial. The overall trial randomized 387 previously treated mCRPC patients with homologous recombination repair, or HRR, gene alterations to receive treatment with olaparib or physician's choice of either enzalutamide or abiraterone. In the biomarker subgroup analysis, patients with BRCA1/2 mutations who received olaparib had a median progression-free survival of 9.8 months and median overall survival of 20.1 months, compared to 3 months and 14.4 months, respectively, for patients treated with hormonal agents.
The NMPA could convert this conditional approval to a full approval contingent on the results of a similar study specifically in Chinese patients. The latest regulatory action in China follows the European Commission's approval of the same olaparib indication last November. In May 2020, the US Food and Drug Administration also approved olaparib for previously treated mCRPC, but for a broader indication that included patients with germline or somatic mutations in HRR genes, including BRCA1/2 and more than a dozen others.
Oncologists questioned the FDA's broader approval when, last September, updated results from PROfound's gene-specific analysis showed that BRCA1/2-mutated patients were driving most of the benefit observed in the broader HRR gene mutation group.
Doctors have also taken issue with the drugmakers' decision to compare olaparib to hormonal therapy in PROfound rather than standard-of-care docetaxel, cabazitaxel, or radium-223. In March, the UK's National Institute for Health and Care Excellence issued a draft guidance saying it would not recommend olaparib for BRCA1/2-mutated mCRPC patients absent a direct comparison to standard treatments.