Cascadian Therapeutics Announces Approval of Nonproprietary Name “tucatinib” for Lead Product Candidate ONT-380

SEATTLE, Aug. 31, 2016 -- Cascadian Therapeutics (NASDAQ:CASC), a clinical-stage biopharmaceutical company, today announced that the United States Adopted Names (USAN) Council and the International Nonproprietary Names (INN) Expert Group have approved the nonproprietary name "tucatinib" for ONT-380, the Company’s lead product candidate for the treatment of advanced, metastatic HER2+ breast cancer.

“We’re pleased to adopt the new nonproprietary name tucatinib for our lead product candidate, ONT-380,” said Scott Myers, President and CEO of Cascadian Therapeutics. “Tucatinib has shown promising systemic activity, encouraging activity against brain metastases, and a favorable safety profile in patients with advanced HER2+ breast cancer. We continue to enroll our Phase 2 combination trial, HER2CLIMB, and plan to report new data from our ongoing Phase 1b ‘Triplet’ study of tucatinib in combination with capecitabine and trastuzumab later this year.”

The USAN Council and the World Health Organization’s INN Expert Group select simple, informative and unique nonproprietary names for drugs based on pharmacological and/or chemical relationships to allow for clear identification and communication among health professionals.

About Cascadian Therapeutics
Cascadian Therapeutics is a clinical-stage biopharmaceutical company dedicated to developing innovative product candidates for the treatment of cancer. Our lead product candidate, tucatinib, also known as ONT-380, is an orally active and selective small molecule HER2 inhibitor, which has been studied in approximately 200 patients to date. Preliminary results from two ongoing Phase 1b studies of tucatinib in combination showed promising systemic activity, a favorable safety profile and encouraging activity against brain metastases. Cascadian Therapeutics is also conducting a randomized, double-blind, placebo-controlled Phase 2 study called HER2CLIMB. The study is evaluating tucatinib versus placebo in combination with capecitabine and trastuzumab in late stage HER2+ breast cancer patients, with and without brain metastases, who have previously been treated with a taxane, trastuzumab, pertuzumab and T-DM1. This study is expected to enroll 180 patients with and without brain metastases across approximately 100 clinical sites in the U.S., Canada, and Western Europe. The Company is also developing a cell cycle inhibitor, Chk1, and plans to move the program forward through IND-enabling studies in 2017. For more information, visit www.cascadianrx.com.

Forward-Looking Statements
In order to provide Cascadian Therapeutics' investors with an understanding of its current results and future prospects, this release contains statements that are forward-looking. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as "believes," "anticipates," "plans," "expects," "will," "intends," "potential," "possible" and similar expressions are intended to identify forward-looking statements. These forward-looking statements include Cascadian Therapeutics' expectations regarding clinical development activities, timing of additional data and potential benefits of its product candidates.

Forward-looking statements involve risks and uncertainties related to Cascadian Therapeutics' business and the general economic environment, many of which are beyond its control. These risks, uncertainties and other factors could cause Cascadian Therapeutics' actual results to differ materially from those projected in forward-looking statements, including the risks associated with the costs and expenses of developing its product candidates, the adequacy of financing and cash, cash equivalents and investments, changes in general accounting policies, general economic factors, achievement of the results it anticipates from its preclinical development and clinical trials of its product candidates and its ability to adequately obtain and protect its intellectual property rights. Although Cascadian Therapeutics believes that the forward-looking statements contained herein are reasonable, it can give no assurance that its expectations are correct. All forward-looking statements are expressly qualified in their entirety by this cautionary statement. For a detailed description of Cascadian Therapeutics' risks and uncertainties, you are encouraged to review the documents filed with the securities regulators in the United States on EDGAR and in Canada on SEDAR. Except as required by law, Cascadian Therapeutics does not undertake any obligation to publicly update its forward-looking statements based on events or circumstances after the date hereof.

Additional Information
Additional information relating to Cascadian Therapeutics can be found on EDGAR at www.sec.gov and on SEDAR at www.sedar.com.

Investor Contact:
Julie Rathbun
Rathbun Communications
206-769-9219
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Tricia Truehart
The Trout Group
646-378-2953
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Media Contact:
Amy Bonanno
BMC Communications
646-513-3117
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