CYTOGEN ANNOUNCES FINDINGS ON QUADRAMET IN PROSTATE CANCER

Cytogen has announced results from a Phase I clinical trial of Quadramet (samarium Sm-153 lexidronam injection) in combination with hormonal therapy and external-beam radiation therapy in high-risk, clinically non-metastatic prostate cancer patients. Data from the study indicate that the combination regimen was well-tolerated with preliminary antitumor activity observed as evidenced by prostate-specific antigen (PSA) responses. Results were presented at the meeting of the American Society for Radiology and Oncology.

Twenty patients with newly diagnosed, high-risk, clinically non-metastatic prostate cancer were treated with a regimen consisting of one month of hormonal therapy followed by a single administration of Quadramet followed by four more months of hormonal therapy in combination with external beam radiation therapy (RT). Quadramet was administered in escalation doses of 0.25 mCi/kg (four patients), 0.5 mCi/kg (four patients), 0.75 mCi/kg (six patients) and 1.0 mCi/kg (six patients). The primary endpoint of the study was assessment of the incidence of grade 3 (or higher) toxicity following all therapy.

Nineteen patients received all planned therapy without any delays, and one patient required surgery before the start of RT. Median follow-up time for the entire group was 19 months. Two patients experienced grade 3 hematologic toxicity, and there were no other grade 3 or 4 side effects. Nadir levels of platelets were significantly lower in the 12 patients receiving Quadramet doses less than 0.5 mCi/kg than in the eight patients receiving less than or equal to 0.5 mCi/kg. At last follow-up, 15 patients had exhibited recovery of testosterone to non-castrate levels following completion of hormonal therapy. Nine of these 15 patients had not had a rise in PSA above 0.2 ng/mL. Researchers concluded that administration of Quadramet in combination with hormonal therapy and RT was safe and feasible in patients with high-risk prostate cancer and that additional follow-up was necessary to determine if the unexpected PSA response rate was durable in nature.