YM BioSciences: Two posters on nimotuzumab accepted for presentation at AACR

- University of Toronto results of nimotuzumab linked to radionuclide -

- Interaction of nimotuzumab with EGFRvIII, a mutant form of EGF receptor frequently expressed in brain tumors -

YM BioSciences Inc. (NYSE YMI, TSX:YM), today announced that two posters have been accepted for presentation at the American Association for Cancer Research (AACR) Annual Meeting to be held from April 17-21 in Washington, DC. The first poster describes the results of the previously reported collaboration with researchers at the University of Toronto for the development of highly potent antibody-radionuclide conjugates for use in the treatment of cancer. The poster will describe activity of 111In-NLS-nimotuzumab against breast cancer cells with high and low EGFR expression. 111In-NLS-nimotuzumab was highly active against cells over-expressing EGFR whereas the nimotuzumab conjugate spared toxicity toward cells with EGFR expression similar to that on most normal epithelial cells.

The poster entitled "111In-NLS-Nimotuzumab: A potent Auger electron-emitting radiotherapeutic agent for EGFR-overexpressing breast cancer" will be presented on Tuesday April 20, from 2-5pm in Exhibit Hall A-C, Poster section 27 by Aisha Fasih, a scientist from the laboratory of Dr. Raymond Reilly, Professor, Leslie Dan Faculty of Pharmacy at the University of Toronto.

"We continue to build upon our knowledge of the cancer-targeting attributes of nimotuzumab which contrast sharply with other approved EGFR-targeting antibodies in that nimotuzumab is selective for cancer cells, thereby minimizing toxicity while preserving efficacy," said David Allan, Chairman & CEO of YM BioSciences Inc. "In addition to greatly improving tolerability, we believe that this property uniquely positions our EGFR-targeting molecule for safe delivery of potent anticancer agents when conjugated to nimotuzumab. This presentation by scientists from the University of Toronto again demonstrates nimotuzumab as an antibody selectively targeting cancer cells overexpressing EGFR and points to the potential of nimotuzumab to safely deliver toxic payloads despite ubiquitous expression of EGFR in normal tissues."

"We are very much looking forward to presenting the results of these studies with 111In-NLS-nimotuzumab to the broader cancer research community at the upcoming AACR meeting," said Professor Raymond Reilly. "This is an excellent opportunity for us to describe our innovative strategy to exploit the nanometer range Auger electrons emitted by 111In for the treatment of cancer. Nimotuzumab has the necessary specificity for breast cancer cells overexpressing EGFR that allowed us to selectively kill these cells with these ultrashort range electrons emitted by 111In."

YM is also developing its IntelliMab(TM) technology which is designed to generate novel antibodies that selectively target cancer cells while avoiding receptors found in normal tissue. This proprietary approach to the design and selection of molecules permits IntelliMab-generated antibodies to maximize anticancer activity while minimizing toxic adverse effects. IntelliMabs are promising for a number of conditions and targets as well as for conjugation to a range of highly potent toxins.

"These data will reinforce our position that antibodies with superior targeting are ideal for delivery of toxic payloads selectively to cancer cells," said Sean Thompson, Vice President of Corporate Development at YM and General Manager of the IntelliMab platform. "IntelliMabs are excellent drug candidates in their own right and should ideally be safe delivery vehicles for use with conjugation technologies. The presentation of data by Dr. Reilly's lab is an important step both for nimotuzumab and the IntelliMab platform."

The second poster presentation describes interaction of nimotuzumab with a mutant form of EGFR called variant III (EGFRvIII). This variant is frequently expressed in glioblastomas and results in enhanced transformation, reduced apoptosis, and resistance to therapy. Nimotuzumab was demonstrated to bind to EGFRvIII with similar strength as to the non-mutant form of the EGF receptor. This adds to the extensive body of knowledge concerning development of nimotuzumab in brain tumours where the antibody demonstrated encouraging results in early clinical trials treating adult and pediatric gliomas. Nimotuzumab is currently in a phase III study in combination with radiation/temozolomide, against radiation/temozolomide alone, with preliminary results expected in the second half of 2010.

The poster entitled "Nimotuzumab, a humanized anti-epidermal growth factor receptor antibody, interacts with EGFRvIII" will be presented Monday April 19, from 9-12pm in Exhibit Hall A-C, Poster Section 31 (Abstract # 1778) by Maria L. Jaramillo, a scientist from the National Research Council Biotechnology Research Institute.

Abstracts for the posters will be posted at the time of presentation at www.ymbiosciences.com.

SOURCE YM BioSciences Inc.