Low-dose abiraterone acetate (AA) taken with a low-fat breakfast is non-inferior to standard-dose AA while fasting among patients with castration-resistant prostate cancer (CRPC), according to a study published in the Journal of Clinical Oncology.1

Studies leading to the approval of AA for CRPC were conducted among patients in a fasting state and may have established the standard dose at a much higher dose than necessary. For this open-label phase 2 study, researchers randomly assigned 72 patients with progressive CRPC to receive low-dose AA 250 mg with a low-fat meal or standard AA 1000 mg while fasting. All patients received prednisone 5 mg twice daily.

Prostate-specific antigen (PSA) levels were measured once per month. Serum testosterone and dehydroepiandrosterone sulfate (DHEA-S) levels were assessed every 3 months along with a radiographic imaging to assess disease burden.

After 12 weeks, patients treated with low-dose AA had a mean log change in PSA levels of -1.59 vs -1.19 among patients treated with standard-dose AA, establishing non-inferiority. The PSA response rate was 58% vs 50% in the low-dose vs standard-dose group, respectively.

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Patients in both treatment arms had a progression-free survival (PFS) of about 9 months. AA concentration levels were, however, higher among patients treated with the standard dose.

AA is the most widely prescribed first-line agent for CRPC and is currently acquired wholesale at nearly $10,000 a month. With these median PFS estimates, switching to a low-dose AA regimen might save patients nearly $300,000.

The authors concluded that “given the pharmacoeconomic implications, these data warrant consideration by prescribers, payers, and patients. Additional studies are indicated to assess the long-term efficacy of this approach.”

Reference

  1. Szmulewitz RZ, Peer CJ, Ibraheem A, et al. Prospective international randomized phase II study of low-dose abiraterone with food versus standard dose abiraterone in castration-resistant prostate cancer. J Clin Oncol. 2018 Mar 28. doi: 10.1200/JCO.2017.76.4381