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Calithera Biosciences Gains Exclusive, Worldwide License to Mars Symbioscience's Arginase Inhibitors


SOUTH SAN FRANCISCO, Calif., Dec. 9, 2014 (GLOBE NEWSWIRE) -- Calithera Biosciences, Inc. (Nasdaq:CALA) announced today the signing of an exclusive global license agreement with Mars Symbioscience ("Symbioscience"), a division of Mars, Incorporated, granting Calithera rights to research, develop and commercialize Symbioscience's portfolio of arginase inhibitors, discovered as part of Mars' cocoa flavanol research program, for use in human healthcare. Symbioscience's preclinical arginase inhibitor program will enhance Calithera's efforts to submit an Investigational New Drug application for an arginase inhibitor with the FDA for the treatment of cancer near the end of 2015. 

"We believe that drugs targeting immuno-oncology and tumor metabolism pathways have the potential to be transformational in the treatment of cancer, and at Calithera, we are dedicated to researching and developing potential first-in-class therapies that could significantly advance these promising fields of research," said Susan M. Molineaux, PhD, President and CEO, Calithera Biosciences. "I am particularly excited about this agreement because we believe we can apply our core expertise in tumor biology to rapidly advance Symbioscience's potent and selective small-molecule arginase inhibitors into the clinic to develop a first-in-class immuno-oncology therapy for cancer patients."

Under the terms of the agreement, Calithera will obtain exclusive, worldwide rights to Symbioscience's arginase inhibitors for drug research, development and commercialization. Symbioscience will receive an upfront payment and will be eligible to receive future development and commercialization milestones as well as royalties on sales of approved products. 

About Tumor Immunology and Arginase Inhibitors

The field of tumor immunology is focused on developing agents that activate the body's own immune system to attack and kill tumors. Calithera's preclinical program in tumor immunology is focused on developing selective inhibitors of the enzyme arginase, an enzyme produced by myeloid derived suppressor cells in the tumor microenvironment that depletes arginine, a naturally occurring amino acid that is critical for the activation, growth and survival of the body's cancer-fighting cytotoxic T cells. Depletion of arginine due to elevated levels of arginase has been observed in renal cell carcinoma and acute myeloid leukemia patients. By inhibiting arginase, it may be possible to restore the tumor killing activity of cytotoxic T cells by preventing the depletion of arginine. Symbioscience has discovered novel compounds that selectively and potently inhibit arginase activity which may have therapeutic potential in the treatment of cancer.

About Calithera Biosciences

Calithera Biosciences is a clinical-stage company focused on discovering and developing novel small molecule drugs directed against tumor metabolism and tumor immunology. Calithera's lead clinical candidate, CB-839, is a first-in-class inhibitor of glutaminase, a critical enzyme in tumor metabolism, and is currently being tested in patients with solid and hematological cancers. Calithera Biosciences is headquartered in South San Francisco. For more information about Calithera Biosciences, please visit

About Mars Symbioscience

Mars Symbioscience is a technology-based health and life sciences business focused on evidence-based product development. First established in 2005, Mars Symbioscience acts as an incubator for business ideas generated throughout Mars business segments. Pioneering some of the most innovative and breakthrough fundamental scientific research, Symbioscience is developing solutions that translate science into products which have a positive impact on people, pets and the planet.

Forward-Looking Statements

This news release contains forward-looking statements by Calithera that involve risks and uncertainties. These statements include those related to the potential of Calithera to rapidly move Symbioscience's potent and selective small molecule arginase inhibitors into the clinic to develop a first-in-class immuno-oncology therapy for cancer patients and that drugs targeting immuno-oncology; that the inhibition of arginase activity may have therapeutic potential in the treatment of cancer; and the potential of tumor metabolism pathways to be transformational in the treatment of cancer. Actual results may differ from Calithera's expectations and important factors that could cause actual results to differ materially. Calithera's arginase program or other potential product candidates that Calithera develops may not progress through clinical development or receive required regulatory approvals within expected timelines or at all. In addition, clinical trials may not confirm any safety, potency or other product characteristics described or assumed in this press release. Such product candidates may not be beneficial to patients or successfully commercialized. The failure to meet expectations with respect to any of the foregoing matters may have a negative effect on Calithera's stock price. Additional information concerning these and other risk factors affecting Calithera's business can be found in Calithera's filings with the Securities and Exchange Commission at These forward-looking statements are not guarantees of future performance and speak only as of the date hereof, and, except as required by law, Calithera disclaims any obligation to update these forward-looking statements to reflect future events or circumstances.

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