Comparison of two doses of cabazitaxel plus prednisone in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) previously treated with a docetaxel (D)-containing regimen.

Abstract

TPS4692^ Background: The phase III TROPIC study (NCT00417079) reported a significant improvement in overall survival (OS) for cabazitaxel (Cbz) + prednisone (P;CbzP) (25 mg/m2 IV Q3W/10 mg PO QD) vs mitoxantrone (M) + P (MP) (median OS 15.1 vs 12.7 mos; HR 0.70; P < 0.0001) in pts with mCRPC (also known as hormone-refractory prostate cancer) previously treated with a D-containing regimen. CbzP is approved by the FDA, EMA and other health authorities for the treatment of pts with mCRPC that has progressed after a D-containing regimen. Cbz toxicity is consistent with other taxanes; compared with M, more hematologic toxicities are reported (primarily Grade 3–4 neutropenia). Phase I/II studies identified 20 and 25 mg/m2 as recommended doses; 25 mg/m2 was selected for the phase III TROPIC study. As pooled data show Grade 3–4 neutropenia incidence is lower with Cbz < 25 mg/m2 (61%) vs ≥ 25 mg/m2 (74%), it is of interest to assess if reducing the Cbz approved dose in mCRPC lessens hematologic toxicity and is non-inferior in terms of efficacy. Methods: PROSELICA (NCT01308580) is a randomized, open-label, multinational, phase III study comparing 20 mg/m2 and 25 mg/m2 Cbz for efficacy and tolerability. Pts with a life expectancy > 6 mos, ECOG PS ≤ 2, histologically/cytologically confirmed metastatic prostate adenocarcinoma resistant to hormone therapy and previously treated with a D-containing regimen are eligible. Pts are randomized 1:1 to receive Cbz 20 mg/m² or 25 mg/m² IV Q3W + P 10 mg PO QD, treated until disease progression, unacceptable toxicity or withdrawal of consent (max 10 cycles), and stratified according to ECOG PS, measurable disease (yes/no) and region. The primary endpoint is OS (non-inferiority design). Secondary endpoints include safety, progression-free survival (PCWG2 criteria), PSA and pain progression and response, tumor response in pts with measurable disease and health-related quality of life. Cbz PK and pharmacogenomics will be assessed in pt subgroups. Planned enrollment is 1,200 pts. Study start was in May 2011; as of Jan 2012, 270 pts had been enrolled. The first DMC meeting recommended continuing the study without change.