Highlights from

ASCO 2021

American Society of Clinical Oncology annual meeting

Virtual 4-8 June 2021

Addition of abiraterone to ADT (plus docetaxel) nearly doubles survival of de novo metastatic prostate cancer

Summary: First results from the phase III PEACE-1 trial show that adding abiraterone to androgen deprivation therapy (ADT) plus docetaxel significantly improves progression-free survival in patients who present with de novo metastatic castration-sensitive prostate cancer (mCSPC) without meaningful added short-term toxicity.

Historically, ADT was the standard of care for men with mCSPC. Since 2015, combining ADT with either docetaxel, novel hormonal therapies (abiraterone, enzalutamide), or radiotherapy to the primary tumour was shown to improve overall survival and thus became the new standard of care.1-4 However, it is unknown whether combining these new treatments on top of ADT further increments outcomes. The primary goal of the PEACE-1 trial (NCT01957436) is to evaluate the efficacy and safety of the addition of abiraterone, radiotherapy, or abiraterone plus radiotherapy to standard of care. A total of 1,173 men with de novo mCSPC were randomised to standard of care, standard of care plus abiraterone, standard of care plus radiotherapy, or standard of care plus abiraterone plus radiotherapy. No interaction was detected between the effect of abiraterone and that of radiotherapy (P=0.64), allowing to pool abiraterone arms for comparisons: 589 patients were enrolled in the standard of care (± radiotherapy) arm and 583 patients were enrolled in the standard of care (± radiotherapy) plus abiraterone arm. The trial has two co-primary endpoints of radiographic progression-free survival and overall survival.

Dr Karim Fizazi (Institut Gustav Roussy, France) presented the first results of PEACE-1.5 After a median follow-up of 3.5 years, median radiographic progression-free survival was 4.5 years in the standard of care plus abiraterone arm versus 2.2 years in the standard of care arm. Median castration-resistant-free survival was 3.8 years and 1.5 years, respectively. Relative improvement of progression-free survival was comparable in patients treated with or without docetaxel. No meaningful additional toxicity was observed in patients treated with standard of care plus abiraterone. “Adding abiraterone to ADT or to ADT plus docetaxel significantly improves progression-free survival in men with de novo metastatic prostate cancer, with about 2.5 years of absolute benefit in medians, and no meaningful additional short-term toxicity,” Dr Fizazi concluded.

  1. Sweeney CJ, Chen Y-H et al. Chemohormonal therapy in metastatic hormone-sensitive prostate cancer. N Engl J Med 2015;373:737-746 [full text]
  2. Fizazi K, Tran N et al. Abiraterone plus prednisone in metastatic, castration-sensitive prostate cancer. N Engl J Med 2017;377:352-360 [full text]
  3. Davis ID, Martin A J et al. Enzalutamide with standard first-line therapy in metastatic prostate cancer. N Engl J Med 2019;381:121-131 [full text]
  4. Parker CC, James N D et al. Radiotherapy to the primary tumour for newly diagnosed, metastatic prostate cancer (STAMPEDE): a randomised controlled phase 3 trial. Lancet 2018;392:2353-2366 [full text]
  5. Fizazi K et al. A phase 3 trial with a 2x2 factorial design of abiraterone acetate plus prednisone and/or local radiotherapy in men with de novo metastatic castration-sensitive prostate cancer (mCSPC): First results of PEACE-1. Abstract 5000, ASCO 2021, 4-8 June 2021

Top image: FatCamera

Article image: Mark Kostich

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