Castration-Resistant Prostate Cancer clinical trials

CABAzitaxel With or Without Prednisone in Patients With Metastatic CAstration REsistant Prostate Cancer Progressed During or After a Previous Docetaxel-based Chemotherapy

Patients with metastatic castration resistant prostate cancer (mCRPC) progressed during or after a previous docetaxel-based chemotherapy, for whom cabazitaxel has been scheduled as per clinical practice and label indication. In the "TROPIC" Trial, cabazitaxel, administered concomitantly with prednisone 10 mg daily, showed a significant advantage vs. mitoxantrone in both Overall Survival (OS) and Progression Free Survival (PFS) / radiographic PFS in patients failing docetaxel-based chemotherapy. Similar to docetaxel, cabazitaxel has been approved in combination with daily prednisone, but the benefits of adding daily corticosteroids to taxane chemotherapy remain to be proven. In fact, corticosteroids have a variety of biological effects, and a number of studies in large cohorts of patients show that they may have both favourable effects, mediated by adrenal androgen and cytokine suppression, and detrimental effects related to their adverse events associated with their long-term use as well to the potential promiscuous activation of the AR. In fact, prednisone and dexamethasone can activate some AR variants that make tumors sensitive to glucocorticoids even at low concentrations. It has been showed that point mutations of the AR, which appear to cluster in the ligand-binding domain, are rare in therapy naive patients but occur in 15- 45% of patients with castration-resistant disease and can increase AR affinity for a wide range of steroids. On the other hand, insofar as safety is concerned, omitting daily corticosteroids does not seem to increase toxicity (e.g. hypersensitivity reactions). In fact, in the CHARTEED trial, docetaxel was safely administered without daily corticosteroids. Safety data about the use of cabazitaxel without daily prednisone/prednisone alone are missing. The CABACARE study is designed to assess the effects in terms of efficacy, safety as well as quality of life of omitting daily corticosteroids in patients treated with cabazitaxel. Furthermore, the CABACARE study evaluates the mutational status of the RB gene as well as presence of AR-V7 variant. The AR-V7 status assessed in circulating tumor cells has a strong predictive value for abiraterone/enzalutamide effectiveness, but its role in patients receiving cabazitaxel requires to be defined.