ESMO 2018: Cabazitaxel Treatment in mCRPC Clinical Trials Compared to Usual Care In CAPRI: An Observational Study In The Netherlands

Munich, Germany ( TROPIC was a randomized open label phase III clinical trial which compared the efficacy of cabazitaxel to mitoxantrone in patients with mCRPC who had progressed on docetaxel1. 755 men were randomized and included in the intention to treat analysis. At the time of final analysis, cabazitaxel improved overall survival (15.1 vs 12.7 months, HR 0.7, p<0.0001) as well as median progression free survival. In the cabazitaxel cohort, the most common grade 3 or higher adverse events were neutropenia (82%), leukopenia (68%), anemia (11%), and diarrhea (6%). 8% of patients experienced febrile neutropenia. Since the phase III study, several prospective observational studies of real world use of cabazitaxel have been described, one in a Japanese cohort, and another in a French cohort2,3. Matsuyama et al described the safety and efficacy of cabazitaxel in 662 patients with mCRPC. The safety profile was similar to TROPIC but there were significant differences in overall survival depending on the dose of cabazitaxel used (25 mg/m2 vs 20 mg/m2). Oudard et al found that the real life median OS in their cohort was 11.9 months, compared with the 15.1 months found in TROPIC2. This abstract adds to this literature by describing another cohort of patients in the real world treated with cabazitaxel.

In this study, clinical data were abstracted from 109 men with mCRPC who were treated with cabazitaxel in the Netherlands. Many patient characteristics were similar between the real-world cohort and the clinical trial cohort, including age, time on androgen deprivation therapy, alkaline phosphatase, median PSA, ECOG performance status, and opioid use.

UroToday ESMO2018 TROPIC

However, a few differences did exist. Those treated in outside of the clinical trial had a lower hemoglobin (7.1 vs 7.7), higher LDH (328 vs 268), more visceral disease (19% vs 11%), were symptomatic (78 vs 72%), had fewer cycles of docetaxel (7 vs 10), and had a shorter time since last docetaxel infusion (2.2 months vs 3.9 months). The median overall survival for non-trial patients was 9.6 months, which is similar to what Oudard et al reported as well. This is likely due to treating a sicker population of patients outside of clinical trials, as described by the differences in patient characteristics above.

UroToday ESMO2018 TROPIC 2a
Figure 1: Overall survival cabazitaxel directly post-docetaxel, SOC vs in trial

This study demonstrates that patients treated with cabazitaxel as part of the standard of care may not have the same overall survival as those who were recruited for the original TROPIC clinical trial. This is largely due to a greater number of negative prognostic factors in the real world cohort, as more patients had a visceral disease, higher LDH, and lower hemoglobin. Future studies should investigate whether any biomarker is able to help risk stratify and choose the best candidates for cabazitaxel after docetaxel failure in patients with mCRPC.

Presented by: Hans M. Westgeest, Medical Oncologist, Breda, the Netherlands

Written By: Jason Zhu, MD. Fellow, Division of Hematology and Oncology, Duke University, Twitter: @TheRealJasonZhu at the 2018 European Society for Medical Oncology Congress (#ESMO18), October 19-23,  2018, Munich Germany
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