Lorus Therapeutics Announces Publication of a Clinical Study Demonstrating Encouraging Results with LOR-2040 in Combination with Cytarabine in Patients with Acute Myeloid Leukemia

07-02-2008

Lorus Therapeutics Inc. (TSX: LOR, AMEX: LRP) ("Lorus" or the "Corporation"), a biopharmaceutical company specializing in the research and development of pharmaceutical products and technologies for the management of cancer, today announced publication by an Ohio State University (OSU) clinical team of a paper entitled "Phase I Study of GTI-2040, an Antisense to Ribonucleotide Reductase, in Combination with High-Dose Cytarabine in Patients with Acute Myeloid Leukemia" (Clinical Cancer Research 2008; 14 (12): 3889-3895). This was the first clinical study in AML with GTI-2040, now known as LOR-2040.

The primary author, Dr Rebecca Klisovic and the Principal Investigator, Dr Guido Marcucci, in the Division of Hematology and Oncology at OSU carried out the study under the sponsorship of the National Cancer Institute (NCI) Cancer Therapy Evaluation Program (CTEP). Lorus is collaborating with the Division of Cancer Treatment and Diagnosis, NCI on the development of LOR-2040 under a Clinical Trials Agreement. All patients in the study received LOR-2040 and high dose cytarabine in therapeutic doses within a dose escalating design, which determined a well-tolerated recommended Phase II dose.

In this study, the authors examined the relationship of the targeted activity of LOR-2040 to clinical responses in AML patients less than 60 years of age. Downregulation of R2, the target of LOR-2040, after 24 hours of LOR-2040 was statistically significant and was associated with complete remission. The authors have also now reported for the first time that outcomes of complete response were associated with high pre-treatment levels of R2, which were statistically significant compared to nonresponders. This finding suggests that pre-treatment R2 levels may be a predictor of response, and provide a possible basis for treatment stratification to LOR-2040 and high dose cytarabine combination.

Favorable disease responses included complete responses in 35% of the 23 patients and significant cytoreduction of leukemic blasts in two others. As a further favourable outcome, these two patients and five of the patients who had complete responses were able to progress to a successful transplant, a desired outcome of successful salvage therapy. Notably, the study population included unfavourable patients with at least one adverse prognostic characteristic.

The clinical study also measured intracellular uptake of LOR-2040 in the bone marrow leukemic cells, and identified significant accumulation of the drug in the bone marrow blast cells and suggested preferential uptake of the drug by CD34+ cells, an important malignant bone marrow cell population.

The authors concluded that LOR-2040 in combination with high dose cytarabine is feasible, is active against its target R2, and "holds promise in younger patients with refractory or relapsed AML". The tolerability profile of this combination regimen was assessed as similar to that expected from high dose cytarabine alone.

"This successful clinical study has provided a detailed supporting rationale for our ongoing development program with LOR-2040 in AML", said Dr Aiping Young, Lorus' President and CEO. "This study supports Lorus' view that a highly specific targeted therapy approach can achieve efficacy with minimal impact on toxicity".

A Phase II program with LOR-2040 in this combination is presently ongoing to extend and confirm these findings in patients with refractory or relapsed AML.

About LOR-2040

LOR-2040 (formerly GTI-2040) is an antisense drug that specifically targets the R2 component of ribonucleotide reductase, which is required for DNA synthesis and cell proliferation. Through downregulation of R2, LOR-2040 has demonstrated strong antitumor and antimetastatic activity in a variety of tumor types in both in vivo and in vitro models and is under study in a multiple Phase I/II clinical program. R2 has been described as a malignant determinant that is elevated in a wide range of tumors, which can cooperate with a variety of cellular cancer causing genes known as oncogenes to enhance tumor growth and metastatic potential.

About Lorus

Lorus is a biopharmaceutical company focused on the research and development of novel therapeutics in cancer. Lorus' goal is to capitalize on its research, preclinical, clinical and regulatory expertise by developing new drug candidates that can be used, either alone, or in combination with other drugs, to successfully manage cancer. Through its own discovery efforts and an acquisition and in-licensing program, Lorus is building a portfolio of promising anticancer drugs. Lorus Therapeutics Inc. is listed on the Toronto Stock Exchange under the symbol LOR, and on the American Stock Exchange under the symbol LRP.

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Lorus Therapeutics Inc.'s recent press releases are available through the Company's website at http://www.lorusthera.com/. For Lorus' regulatory filings on SEDAR, please go to http://www.sedar.com/. For SEDAR filings prior to July 10, 2007 you will find these under the company profile for Global Summit Real Estate Inc. (Old Lorus).

CONTACT: Lorus Therapeutics Inc., Dr. Saeid Babaei, (416) 798-1200 ext.490, ir@lorusthera.com