A Study of Radium-223 in Combination With Tasquinimod in Bone-only Metastatic Castration-Resistant Prostate Cancer

This is a study of Radium-223 in combination with Tasquinimod. The target population is patients with bone metastases from castration-resistant prostate cancer intended for treatment with radium-223. After baseline assessment, all subjects will receive six cycles of Radium-223 separated by an interval of 28 days. Radium-223 will be administered per FDA-approved dosing (six IV injections at a dose of 50kBq/kg of body weight, administered every 4 weeks). The treatment maintenance dose of tasquinimod will be a maximum of 1 mg of tasquinimod taken once daily with water (\~200 mL). The initial target dose of tasquinimod is 0.5mg/day. All subjects will be followed up for 12 months after start of study treatment. The investigators propose a phase I/Ib trial of the addition of tasquinimod to FDA-approved doses of radium-223 in men with symptomatic bone-only metastatic CRPC. The investigators anticipate that given their distinct mechanisms of action and non-overlapping toxicity profiles that additive or synergistic toxicity would be minimal. The investigators hypothesize that adding tasquinimod to radium therapy may result in improved measures of efficacy including reduction in total alkaline phosphatase, time to first skeletal-related event and PSA and radiographic progression-free survival. In the Phase I portion of dose-escalation scheme, the dose escalation will follow a 3+3 design with intra-patient dose-escalation from 0.25mg/day of tasquinimod to a goal dose of either 0.25mg (dose-level -1), 0.5mg (dose-level 1), or 1.0mg/day (dose-level 2) based on individual tolerability. Upon identifying a recommended Phase II combination dose-level of Radium-223 and tasquinimod, the investigators will move to the Phase Ib portion and open an expanded cohort of up to 35 additional patients to achieve a total of 38 patients treated at the recommended phase II dose-level (including those from the dose-escalation phase).