medwireNews: Overall survival (OS) rates among men receiving cabazitaxel for metastatic castration-resistant prostate cancer (mCRPC) are lower in everyday oncology practice than previously observed in clinical trials, French study data show.
The difference seen was mainly “due to the presence of features of poor prognosis at baseline and use of cabazitaxel in 3rd line or beyond in 82% of patients,” write Nicholas Moore (University of Bordeaux) and co-authors in the British Journal of Cancer.
They add: “There were no unexpected safety issues, with severe neutropenia being the most important risk to consider when prescribing cabazitaxel.”
Their multicenter postmarketing surveillance study included 401 French men (median age 70 years) with mCRPC who began treatment with cabazitaxel between 2013 and 2015. All of the men had previously received docetaxel, and 82% had also been treated with abiraterone, enzalutamide, or both.
Moore and team report that cabazitaxel was typically given every 3 weeks (90.8%) at a starting dose of 25 mg/m2 (50.5%). The median treatment duration was 3.4 months, and among the 95% of patients who discontinued cabazitaxel during the 18-month follow-up period, the most common reasons given were disease progression or death (83.2%), or the occurrence of adverse events (AEs; 15.2%).
At 18 months, just under a third (32.4%) of patients were still alive, with a median OS duration of 11.9 months.
Moore et al note that this was shorter than the median OS reported in the “pivotal” TROPIC trial (15.1 months), as well as in the PROSELICA clinical trial (13.4 and 14.5 months at doses of 20 and 25 mg/m2, respectively).
Multivariate analysis revealed that a number of pretreatment and patient variables were significantly associated with shorter OS. These included experiencing at least one grade 3 or higher adverse event (hazard ratio [HR] for death=2.05), the presence of visceral metastases (HR=1.98) or more than five bone metastases (HR=1.74), the use of more than five concomitant non-cancer treatments at baseline (HR=1.74), progressing during docetaxel treatment (HR=1.69), being less than 10 years since PC diagnosis (HR=1.52), and a plasma prostate-specific antigen level above 135 ng/mL (HR=1.36).
The researchers also calculated the progression-free survival (PFS) rate, which was 32.4% at 6 months and 3.1% at 18 months, with a median PFS duration of 3.9 months.
The AE rates and profiles observed in the current study were “essentially similar” to those observed in the clinical trials, the researchers remark. More than half (55.4%) of patients experienced at least one AE of grade 3 or higher, with 26.6% needing hospitalization.
The most common grade 3 or higher AEs were anemia (26.9%), neutropenia (15.0%) including febrile neutropenia (8%), leukopenia (9.5%), renal failure (7.2%), thrombocytopenia (5.2%), and septicemia and septic shock (5.0%). There were six treatment-related deaths, five of which were due to sepsis or septic shock with febrile neutropenia.
By Laura Cowen
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Br J Cancer 2019; doi:10.1038/s41416-019-0611-6