Positive results from YM BioSciences' CYT997 Phase I study for vascular disruption in tumors

-CYT997 well tolerated at doses associated with vascular disruption in tumors-

YM BioSciences Inc. (NYSE Amex: YMI, TSX:YM), today announced the publication of Phase I results demonstrating that CYT997, a novel vascular disrupting agent (VDA), was well tolerated at doses that were associated with pharmacodynamic evidence of vascular disruption in tumors. The article entitled "Phase I trial of CYT997, a novel cytotoxic and vascular-disrupting agent," was published in the premier cancer journal, the British Journal of Cancer. CYT997 is an orally bioavailable agent with dual mechanisms of vascular disruption and cytotoxicity and has the potential to be broadly active against a range of tumor types. CYT997 is currently in a Phase II clinical trial for glioblastoma multiforme, a brain cancer with poor prognosis, with data expected in Q2 2011.

"The ability of solid tumors to grow blood vessels is essential to their survival, growth and metastasis. Vascular disrupting agents such as CYT997, that damage or inhibit the formation of tumor blood vessels, have the potential for significant anti-cancer activity," said Dr. Nick Glover, COO of YM BioSciences. "In addition to its broad applicability and the favorable safety results reported in the British Journal of Cancer, we were also very encouraged to observe promising signs of disease control in this study, particularly as CYT997 was given as monotherapy. Furthermore, CYT997 can be administered both orally and intravenously, which differentiates this molecule from most other VDAs in development which can only be administered intravenously."

Thirty-one patients received CYT997 by continuous intravenous infusion over 12 dose levels (7-358 mg/m(2)). Doses up to 202 mg/m(2) were well tolerated. Dose-limiting toxicities were observed at 269 and 358 mg/m(2), consisting of grade 3 prolonged corrected QT interval in two patients and grade 3 hypoxia and grade 4 dyspnea in one patient. All toxicities were reversible. The pharmacokinetics of CYT997 were linear over the entire dose range. CYT997 administration was associated with changes in plasma and imaging biomarkers that were consistent with vascular disruption in tumors. Dynamic contrast-enhanced magnetic resonance imaging scans showed significant changes in tumor perfusion consistent with vascular disruption in 7 out of 11 evaluable patients treated at CYT997 doses of (greater than or equal to) 65 mg/m(2). Moreover, plasma levels of the vascular biomarkers, von Willebrand factor and caspase-cleaved cytokeratin-18, increased post-treatment in several patients at higher dose levels. Among 22 patients evaluable for response 18 (82%) achieved stable disease for greater than 2 cycles while 6 (27%) completed all 6 cycles as specified in the protocol.

The abstract and full text of the article is available online at www.bjcancer.com and appears in the British Journal of Cancer, issue number 103, pages 597-606.

About YM BioSciencesSOURCE YM BioSciences Inc.