Encouraging responses seen with Xyotax in prostate cancer patients

Prostate Cancer :: Encouraging responses seen with Xyotax in prostate cancer patients

Cell Therapeutics, Inc. (CTI) announced preliminary results from a investigator-sponsored phase II study of XYOTAX(TM) (paclitaxel poliglumex) in patients with androgen independent prostate cancer, the majority of whom had failed prior treatment with taxane chemotherapy.

The results, presented in Orlando at The Prostate Cancer Symposium co-sponsored by the American Society of Oncology (ASCO), the American Society for Therapeutic Radiology and Oncology (ASTRO), and the Society of Urologic Oncology (SUO), demonstrated a major response rate of 24 percent (five of 21 patients) with a median overall survival at follow up of 8.5 months and a median time to progression of 3.5 months. Of the 24 patients on the study, 80 percent (n = 19) had received prior chemotherapy and 84 percent of those patients (16 of 19) were resistant or refractory to prior taxane chemotherapy. Patients treated every three weeks (n = 9) experienced more grade 3/4 toxicities than those patients treated every four weeks (n = 15). No grade 4 neuropathy was seen in either dosing schedule and only one case of grade 4 neutropenia was seen in the monthly dosing schedule.

"The activity of XYOTAX in this setting is encouraging given that two- thirds of the patients had failed prior docetaxel therapy, suggesting that XYOTAX may offer an alternative to such patients. Importantly XYOTAX was administered in a short, ten to twenty minute, infusion without routine pre- medications. On a monthly dosing regimen, the only grade 4 toxicity was uncomplicated neutropenia," noted Robert Amato, D.O., Director, Genitourinary Oncology Program at The Methodist Hospital Research Institute in Houston. "The next phase of the study will explore the ability of estrogen supplementation to further increase the major response rate in this difficult to treat population of patients with prostate cancer."

The study continues to enroll and follow patients and the protocol has been amended to include the use of estrogel with XYOTAX to determine safety and if efficacy is enhanced.

As previously reported, preclinical data show that in estradiol supplemented female mice, XYOTAX demonstrated a nearly two-fold increase in anti-tumor activity compared to non-supplemented animals in a colon cancer tumor model. Also, in previous phase III clinical trials in lung cancer, XYOTAX demonstrated the greatest survival advantage in women with normal estrogen levels.