Adding mitoxantrone and prednisone (MP) to adjuvant androgen-deprivation therapy (ADT) does not improve overall survival (OS) or disease-free survival (DFS) among patients with high-risk prostate cancer, according to a study published in the Journal of Clinical Oncology.1

For this phase 3 study (ClinicalTrials.gov Identifier: NCT00004124), investigators randomly assigned 961 patients with prostate cancer with 1 or more high-risk factors who underwent radical prostatectomy to receive ADT therapy (goserelin plus bicalutamide) alone for 2 years or ADT plus 6 cycles of MP.

After 9.5 years of patient accrual, the Southwest Oncology Group’s Data Safety Monitoring Committee (SWOG DSMC) recommended discontinuing enrollment after noting an increased incidence of acute myelogenous leukemia among patients receiving MP. Patients assigned to ADT plus MP discontinued mitoxantrone.

With a median follow-up of 11.2 years, the 10-year OS estimates were 87% vs 86% for ADT vs ADT plus MP (hazard ratio [HR], 1.06; 95% CI, 0.79-1.43; P = .70), respectively; the investigators’ pretrial estimate was 50%. The estimated 10-year DFS — the secondary outcome of the study — was 72% in both study arms (HR, 1.01; 95% CI, 0.80-1.27; P = .94).

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The cause of death was prostate cancer among 18% vs 22% of patients receiving ADT vs ADT plus MP, respectively, and a higher rate of patients in the MP arm died because of other cancers (36% vs 18%).

The authors concluded that, though an improvement vs estimates was seen in the ADT only arm, “a definitive conclusion regarding value of ADT may not be made without a nontreatment control arm.”

Reference

  1. Hussain M, Tangen CM, Thompson Jr IM, et al. Phase III intergroup trial of adjuvant androgen deprivation with or without mitoxantrone plus prednisone in patients with high-risk prostate cancer after radical prostatectomy: SWOG S9921. J Clin Oncol. 2018 Apr 6. doi: 10.1200/JCO.2017.76.4126 [Epub ahead of print]