'Encouraging' Major Responses Seen With Xyotax in Patients With Taxane-Resistant Androgen Independent Prostate Cancer
ORLANDO, Fla, February 26, 2007 /PRNewswire-FirstCall/ -- Cell Therapeutics, Inc. (CTI) today 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."
Phase II Study of XYOTAX for Androgen Independent Prostate Cancer
Median age of patients on the study is 68 (range 52 to 83), with 83 percent of patients (20 of 24) having a Gleason score of 7-10, which is a poor prognostic factor. A majority of patients (19 of 24 or 80 percent) received prior chemotherapy and of those 84 percent (16 of 19) were resistant or refractory to taxanes.
Preliminary results in 24 patients at time of follow up showed a median time to progression of 3.5 months (range 2 to 10 months) and median overall survival of 8.5 months (range 1.7 to 22.4 months). Three patients had a major PSA response (>/=50% decrease) after two cycles of therapy and two patients with baseline metastatic disease achieved a partial response (PR). PSA velocity was reversed in 12 out of 22 patients (55 percent). In the nine patients treated on the 3-week cycle, one case each of grade 4 neutropenia and lymphopenia were observed; in the 15 patients treated on the 4-week cycles only one case of grade 4 neutropenia was observed; there were more instances of grade 3 side effects, including neuropathy and hematologic toxicities, noted on the 3-week cycle.
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.
For more information about this presentation or CTI's clinical trials, please visit our website at www.cticseattle.com.
XYOTAX(TM) (paclitaxel poliglumex) is a biologically-enhanced chemotherapeutic that links paclitaxel, the active ingredient in Taxol(R), to a biodegradable polyglutamate polymer, which results in a new chemical entity. When bound to the polymer, the chemotherapy is rendered inactive, potentially sparing normal tissue's exposure to high levels of unbound, active chemotherapy and its associated toxicities. Blood vessels in tumor tissue, unlike blood vessels in normal tissue, are porous to molecules like polyglutamate. Based on preclinical studies, it appears that XYOTAX is preferentially distributed to tumors due to their leaky blood vessels and trapped in the tumor bed allowing significantly more of the dose of chemotherapy to localize in the tumor than with standard paclitaxel. Once inside the tumor cell, enzymes metabolize the protein polymer, releasing the paclitaxel chemotherapy. Preclinical and clinical studies support that XYOTAX metabolism by lung cancer cells may be influenced by estrogen, which could lead to enhanced release of paclitaxel and efficacy in women with lung cancer compared to standard therapies.
About Cell Therapeutics, Inc.
Headquartered in Seattle, CTI is a biopharmaceutical company committed to developing an integrated portfolio of oncology products aimed at making cancer more treatable. For additional information, please visit www.cticseattle.com.
This press release includes forward-looking statements that involve a number of risks and uncertainties, the outcome of which could materially and/or adversely affect actual future results. Specifically, the risks and uncertainties that could affect the development of XYOTAX include risks associated with preclinical and clinical developments in the biopharmaceutical industry in general and with XYOTAX in particular including, without limitation, the potential failure of XYOTAX to prove safe and effective for treatment of prostate cancer, determinations by regulatory, patent and administrative governmental authorities, competitive factors, technological developments, costs of developing, producing and selling XYOTAX, and the risk factors listed or described from time to time in the Company's filings with the Securities and Exchange Commission including, without limitation, the Company's most recent filings on Forms 10-K, 8-K, and 10-Q. Except as may be required by Italian law, CTI is under no obligation to (and expressly disclaims any such obligation to) update or alter its forward-looking statements whether as a result of new information, future events, or otherwise.
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Posted: February 2007