Investigator-initiated pilot study of bicalutamide and raloxifene in hormone-resistant prostate cancer.

Abstract

e16065 Background: Estrogens, in addition to androgen may contribute to the progression of prostate cancer.The combination of bicalutamide, a non-steroidal anti-androgen, and raloxifene, a selective estrogen receptor modulator, has a synergistic effect on cell death of prostate cancer cell lines such as DU145 and PC3. We investigated the safety of combined treatment of bicalutamide and raloxifene on quality of life in patients affected by hormone-resistant prostate cancer. Methods: Eligibility requirements included metastatic hormone-resistant prostate cancer, Eastern Cooperative Oncology Group performance status of 0 or 1. Patients received the combination of bicalutamide, 50 mg, and raloxifene, 60 mg, daily in 28 day cycles for a maximum of 6 cycles. The primary endpoint was to describe the adverse event profile of combined treatment with bicalutamide and raloxifene. The secondary endpoint was to describe the quality of life of patients receiving the combination. Adverse events were graded by the investigator using the NCI Common Terminology Criteria for Adverse Events version 4.0 and the quality of life was assessed by the patient using aLinear Analog Scale Assessment (scale of 0-100). Serum levels of estradiol and testosterone were monitored during treatment. Results: Eighteen evaluable patients were included in the statistical analysis after an initial run-in safety cohort of six patients. Two patients completed 6 cycles per protocol, the remaining sixteen patients were taken off protocol after disease progression. Patients completed a median of 2 cycles. There were no grade 4 events and grade 3 adverse events consisted of hypertension (5.6%) and back pain (5.6%). Erectile dysfunction (grade 1) was the most common adverse event (77.8%). Patient assessment of quality of life (mental, physical, social, emotional, spiritual) did not reveal any statistically different changes after 2 cycles of treatment. An analysis of testosterone and estradiol levels will be reported. Conclusions: We conclude that combination of bicalutamide and raloxifene is well-tolerated. The combination of androgen and estrogen receptor blockade warrants further study for efficacy in hormone-resistant prostate cancer. Clinical trial information: NCT01050842.