Safety Profile of the Combination of Prophylactic Pegfilgrastim and Cabazitaxel for Japanese Patients with Castration Resistant Prostate Cancer

: Cabazitaxel, which is a novel semi-synthetic anti-cancerous agent, is newly approved for the treatment of metastatic castration resistant prostate cancer(CRPC). The main dose-limiting toxicity is considered to be febrile neutropenia(FN). In this study, we retrospectively investigated the safety profiles of Japanese patients during cabazitaxel therapy. From September 2014 to August 2016, 17 patients initiated receiving cabazitaxel therapy in our institution. Prophylactically, pegfilgrastim was administered to all patients. Among 17 patients, 5 patients(29.4%)developed FN. Four of these patients(80%)developed FN in the first cycle and could continue the cabazitaxel therapy with dose modification, whereas 1 patient(20%)developed FN leading to septic shock in the 8th cycle. Although he recovered after appropriate medical treatment, he discontinued the cabazitaxel therapy. Regarding non-hematological adverse events, no unknown adverse events were observed. The most frequently observed adverse event was back pain(n=4, 23.5%). There was no influence on the continuation of treatment. Treatment discontinuation due to adverse events was observed in 1 patient(5.9%). Due to the prophylactic pegfilgrastim in combination, the occurrence rate of FN seemed to decrease. However, we must remember that FN is still frequently expressed even under the prophylactic pegfilgrastim.