ESMO 2017: Cabazitaxel followed by ADT improves time to progression in patients with newly diagnosed metastatic hormone sensitive prostate cancer (mHSPC): A Randomized, Open Label, Phase III, Multicenter trial

Madrid, Spain (UroToday.com) Dr. Andrén and colleagues from Sweden presented results of their clinical trial assessing cabazitaxel followed by ADT among men with newly diagnosed metastatic hormone sensitive prostate cancer (mHSPC) at today’s poster session at ESMO 2017 in Madrid, Spain. Patients with newly diagnosed mHSPC have a poor prognosis with a 3-year overall survival (OS) rate of 50%. Recently, combination of docetaxel (75mg/m2 every 6 weeks for 6 cycles) with ADT has become a new standard for such patients, based on results of two large phase III trials showing a significant OS benefit [1,2]. In these trials, docetaxel was initiated within 3 months after the start of ADT. The timing of ADT and chemotherapy is controversial given that the rationale is that ADT will turn clones of tumor cells into a stage of dormancy where chemotherapy is less effective. The objective of this clinical trial was to assess the efficacy of cabazitaxel prior to ADT for patients with newly diagnosed mHSPC.

This phase III trial randomized 31 newly diagnosed mHSPC patients to receive cabazitaxel 25 mg/m2 every 3 weeks for 10 cycles, followed by ADT (immediately after last cabazitaxel cycle, n=15) versus ADT alone (n=16). The primary end-point was OS and the secondary end-point was progression free survival (PFS). The study planned to include 400 patients but was closed prematurely due to low inclusion rate. Of the cabazitaxel treated patients, 66.8% received six cycles or more and 46.7% completed all 10 cycles. Over a median follow up of 31 months, the median OS was 32.5 months with cabazitaxel followed by ADT and 29.5 months with ADT alone (HR 1.43, 95%CI 0.38-5.38). Median PFS was significantly longer in cabazitaxel treated patients (29 vs 12 months; HR 3.96, 95%CI 1.49-10.49). The most common grade ≥ 3 toxicities were neutropenia (66%).

In conclusion, the authors note that results from this prematurely terminated trial suggest that cabazitaxel followed by ADT is effective in newly diagnosed mHSPC and shows a manageable toxicity. If possible, these results will have to be validated in larger randomized trials.

Speaker: Ove Andrén, Orebro University, Orebro, Sweden

Co-Authors: A. Widmark (Umea, Sweden) A. Falt (Orebro, Sweden) E. Ulvskog (Orebro, Sweden) S. Davidsson (Orebro, Sweden) C. Thellenberg Karlsson (Umea, Sweden) M. Hjalm-Eriksson (Stockholm, Sweden)

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, Twitter: @zklaassen_md at the European Society for Medical Oncology Annual Congress - September 8 - 12, 2017 - Madrid, Spain

References:

1. Sweeney CJ, Chen YH, Carducci M, et al. Chemohormonal Therapy in Metastatic Hormone-Sensitive Prostate Cancer. N Engl J Med. 2015;373(8):737-746.
2. James ND, Sydes MR, Clarke NW, et al. Addition of docetaxel, zoledronic acid, or both to first-line long-term hormone therapy in prostate cancer (STAMPEDE): survival results from an adaptive, multiarm, multistage, platform randomised controlled trial. Lancet. 2016;387(10024):1163-1177