Phase IIb study begins for intraprostatic localized PCa drug
The first patient in a phase IIb study evaluating the safety and tolerability of PRX302 (topsalysin) has been dosed, according to Sophiris Bio Inc. The drug, which will be used to treat clinically significant localized prostate cancer, is a pore-forming protein engineered to be activated only in the presence of enzymatically active PSA. The phase IIb study will continue the work of the phase IIa proof-of-concept study that demonstrated that a targeted intraprostatic administration of PRX302 has the potential to safely ablate tumor cells in the prostate. The phase IIb multicenter, open-label study will enroll approximately 40 patients throughout the United States and United Kingdom. Safety and tolerability will be assessed post-treatment over 26 weeks. The study allows enrolled patients the option to retreat with a second dose of PRX302, with a larger biopsy to occur 6 months after the second dose. To be eligible for the retreatment, the patient cannot have experienced a significant adverse response attributable to the drug and the patient will need to have had a clinical response from the first dose but still have a clinical significant lesion area. Data for all patients is expected by the fourth quarter of 2018, and data from patients who did not receive the second retreatment is expected to be available by the first quarter of 2018.
Protocol amended for phase III trial of CRPC agent
Astellas Pharma Inc. and Pfizer Inc. have amended the protocol for the PROSPER trial, a phase III, multinational, randomized, double-blind, placebo-controlled study evaluating the efficacy and safety of enzalutamide (XTANDI) in patients with non-metastatic castration-resistant prostate cancer (CRPC). While the primary endpoint, metastasis-free survival, remains the same, the main purpose of the amendment is to revise the plan for analyses of the primary and secondary endpoints. This reduces the target sample size from 1,560 patients to approximately 1,440 patients. It also allows for quicker results from the study with an anticipated disclosure later this year instead of the original disclosure date of June 2019. Enzalutamide is an androgen receptor inhibitor that blocks multiple steps in the androgen receptor signaling pathway within tumor cells.