Management of metastatic prostate cancer has undergone a revolution over the past decade with the introduction of several novel agents and repurposing of others. Several clinical trials reported improved outcomes with the intensification of androgen deprivation therapy by the addition of docetaxel chemotherapy or novel hormonal agents (abiraterone, enzalutamide, or apalutamide) in the metastatic castration-sensitive state. Relugolix has been recently approved as the first oral gonadotropin-releasing hormone receptor antagonist agent with a superior cardiovascular side-effect profile, and serum testosterone suppression compared with a gonadotropin-releasing hormone agonist, leuprolide. Poly-ADP ribose polymerase inhibitors (olaparib and rucaparib) have demonstrated significant clinical benefit for patients harboring deleterious mutations in genes belonging to the homologous recombination repair pathway and have received Food and Drug Administration approval. Recently, lutetium-177-prostate-specific membrane antigen-617 with standard of care treatment has shown to improve overall survival in men with advanced-stage prostate-specific membrane antigen–positive metastatic castration-resistant prostate cancer. These recent approvals, successes, and the ongoing investigation of multiple novel agents are expected to continue to dramatically improve survival outcomes of men with metastatic prostate cancer in the coming years.
Key Points
Question
What is the comparative effectiveness of single-agent immune checkpoint inhibitors (ICIs) vs taxane chemotherapy in populations of patients with metastatic castration-resistant prostate cancer (mCRPC) defined by levels of tumor mutational burden (TMB)?
Findings
In this comparative effectiveness study of 741 patients with mCRPC, patients with TMB of 10 mutations per megabase (mt/Mb) or greater had significantly longer time to next treatment and overall survival with ICIs vs taxanes.
Meaning
These findings suggest that in scenarios where taxane use is considered, ICIs are a viable alternate treatment option for patients with mCRPC and TMB of 10 mt/Mb or greater.
Background: Both novel hormonal therapies and docetaxel are approved for treatment of metastatic prostate cancer (mPC; in castration sensitive or refractory settings). Present knowledge gaps include lack of real-world data on treatment patterns in patients with newly diagnosed mPC, and comparative effectiveness of novel hormonal therapies (NHT) versus docetaxel after treatment with a prior NHT. Methods: Herein we extracted patient-level data from a large real-world database of patients with mPC in United States. Utilization of NHT or docetaxel for mPC and comparative effectiveness of an alternate NHT versus docetaxel after one prior NHT was evaluated. Comparative effectiveness was examined via Cox proportional hazards model with propensity score matching weights. Each patient’s propensity for treatment was modeled via random forest based on 22 factors potentially driving treatment selection. Results: The majority of patients (54%) received only androgen deprivation therapy for mPC. In patients treated with an NHT, alternate NHT was the most common next therapy and was associated with improved median overall survival over docetaxel (abiraterone followed by docetaxel vs. enzalutamide (8.7 vs. 15.6 months; adjusted hazards ratio; aHR 1.32; p = 0.009; and enzalutamide followed by docetaxel vs. abiraterone (9.7 vs. 13.2 months aHR 1.40; p = 0.009). Limitations of the study include retrospective design.
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