Pfizer’s next-generation androgen receptor (AR) inhibitor Xtandi is the prostate cancer market leader due to its established efficacy across multiple patient segments and a lack of near-term generic competition. Additionally, Xtandi was trialed in combination with leuprolide in the Phase III EMBARK study for non-metastatic hormone-sensitive prostate cancer patients progressing on definitive therapy, where it yielded positive data, leading to FDA approval in November 2023. 

PARP inhibitors Rubraca and Lynparza were both approved in the US in May 2020 for the treatment of metastatic castration-resistant prostate cancer (mCRPC) patients following AR inhibitor therapy. Rubraca received accelerated conditional approval in mCRPC with a deleterious BRCA mutation (germline and/or somatic), while Lynparza received full approval for use in the broader homologous recombination deficient population in the EU, while its FDA approval is only in those patients with BRCA-mutated (BRCAm) tumors. To potentially differentiate the PARP assets, both have been trialed in the first-line setting of mCRPC; Rubraca in combination with Xtandi against Xtandi alone, and Lynparza with abiraterone against abiraterone alone. The latter trial led to an approval, though it is restricted to the BRCAm population, dashing hopes that it would support a wider label.