The combination of bicalutamide and everolimus may be effective in men with bicalutamide-naïve castration-resistant prostate cancer (CRPC), a study published in the journal Cancer has shown.1
Although the mammalian target of rapamycin (mTOR) pathway is up-regulated in CRPC, inhibition of mTOR is not effective in inducing cell death of prostate cancer, possibly due to a compensatory up-regulation effect of the androgen receptor pathway.
Therefore, researchers sought to evaluate the combination of everolimus, an mTOR inhibitor, with bicalutamide, an oral antiandrogen.
For the phase 2 trial, researchers enrolled 24 patients with progressive CRPC who had not previously received bicalutamide (unless to prevent flare) or everolimus. Patients were only eligible if their serum testosterone level was less than 50 ng/dL.
Patients enrolled had an average baseline prostate-specific antigen (PSA) level of 43 ng/dL and a median age of 71.1 years. All patients received bicalutamide 50 mg orally once daily and everolimus 10 mg orally once daily during each 4-week cycle. The average treatment length was 8 cycles.
Results showed that 75% (95% CI: 0.53-0.90) of the 24 patients achieved a PSA response and 62.5% (95% CI: 0.41-0.81) had a 50% or greater reduction in PSA.
Researchers found that median overall survival was 28 months (95% CI: 14.1-42.7).
In terms of safety, 54% (95% CI: 0.37-0.78) of patients developed grade 3 or 4 treatment-related adverse events and a substantial number of patients experienced everolimus-related toxicity.
1. Chow H, Ghosh PM, deVere White R, et al. A phase 2 clinical trial of everolimus plus bicalutamide for castration-resistant prostate cancer [published online ahead of print March 28, 2016]. Cancer. doi:10.1002/cncr.29927.