March 31, 2004

News Release: YM BioSciences doses first patient in pivotal breast cancer study

YM BioSciences Inc. (TSX:YM, AIM:YMBA), the cancer drug development company, today announced that the first patient has been dosed in its 700 patient Phase III registration trial. The international pivotal trial is designed to compare the overall survival differential resulting from the combination of YM's drug, tesmilifene, with the anthracycline, epirubicin, and cyclophosphamide against the use of epirubicin/cyclophosphamide alone in women with metastatic breast cancer.

'We are very pleased to have commenced this important trial on time, and anticipate to have completed enrolment in approximately 18 months,'said Mr. David Allan, Chairman and CEO of YM BioSciences. Tesmilifene is a small molecule chemopotentiator. In the first Phase III trial, which enrolled 305 women, overall survival in women on the combination of tesmilifene with anthracycline (the standard of care in metastatic breast cancer) was greater than 50% longer than for women treated with the standard of care alone. The drug has been clinically demonstrated to increase the effectiveness of the current principal chemotherapeutic drugs, anthracyclines and taxanes, which are used in the majority of cancers.

The current trial is to be conducted in 65 - 70 centers in North America and Europe. YM BioSciences may be able to submit the results for approval of the drug as early as mid 2006 as a result of the previously announced acceptance by the FDA for the application of 'Sequential Analysis'to the patients in the trial. This process is designed to possibly significantly shorten the length of the trial if results similar to the first trial are evident.

Dr. Katherine Pritchard, of Sunnybrook and Women's College Health Sciences Centre in Toronto, was recently announced as the North American Chair of the trial.

About YM BioSciences

YM BioSciences Inc. is a cancer drug development company. In addition to tesmilifene, the Company is developing an EGFr humanized monoclonal antibody that has completed Phase II trials and a GnRH anti-cancer vaccine also in clinical trials. YM is also supporting the preclinical development of two additional cancer products.

Except for historical information, this press release may contain forward-looking statements, which reflect the Company's current expectation regarding future events. These forward-looking statements involve risk and uncertainties, which may cause but are not limited to, changing market conditions, the successful and timely completion of clinical studies, the establishment of corporate alliances, the impact of competitive products and pricing, new product development, uncertainties related to the regulatory approval process and other risks detailed from time to time in the Company's ongoing quarterly and annual reporting.


SOURCE YM BioSciences Inc.

Enquiries: James Smith, The Equicom Group Inc., Tel. +1-416-815-0700 x229, Email: This email address is being protected from spambots. You need JavaScript enabled to view it.; YM BioSciences Inc., Tel. +1-905-629-9761 , Fax +1-905-629-4959, Email: This email address is being protected from spambots. You need JavaScript enabled to view it. (YM.)

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