Safety of Same-day Pegfilgrastim Administration in Metastatic Castration-resistant Prostate Cancer Treated With Cabazitaxel With or Without Carboplatin.

INTRODUCTION: Although myeloid growth factors are commonly used to treat metastatic castration-resistant prostate cancer (mCRPC), the optimal timing of administration has not been well studied. We assessed the effects of same-day pegfilgrastim, a neutrophil stimulator, after cabazitaxel treatment with or without carboplatin in patients with mCRPC. We also evaluated the frequency of urinary tract inflammation during treatment.

PATIENTS AND METHODS: Between September 2010 and September 2014, 151 consecutive patients with mCRPC underwent cabazitaxel treatment with or without the addition of carboplatin at a single institution. We assessed absolute neutrophil count recovery, incidence of neutropenia, neutropenic fever, antibiotic usage, treatment delays or discontinuation, dose reduction, and hospitalization with pegfilgrastim administration. Radiologists blinded to therapy reviewed computed tomography scans to detect urinary tract inflammation.

RESULTS: The median patient age was 69 years (range, 41-88 years); 78% of patients were white, and 54% had a Gleason score ≥ 9. Median overall survival was 9 months (95% confidence interval, 8-11 months). One patient (< 1%) had neutropenia; 38 patients (25%) had infection. During cycle 1, a significantly higher proportion of patients receiving pegfilgrastim after 24 hours developed infection than did those receiving pegfilgrastim the same day (26% vs. 6%; P = .01).

CONCLUSION: Same-day pegfilgrastim administration after cabazitaxel treatment with or without carboplatin in patients with mCRPC is feasible. The urinary tract inflammation rate (21%) was higher than that reported anecdotally. Results need to be prospectively validated.