Exhibit 99.1

Oncothyreon Reports Full Year and Fourth Quarter 2014

Financial Results

Company to Hold Conference Call at 4:30 p.m. EDT Today

SEATTLE, WASHINGTON, March 10, 2015/PRNewswire/ - Oncothyreon Inc. (NASDAQ: ONTY) today reported financial results for the year and quarter ended December 31, 2014.

Net loss for the year ended December 31, 2014 was $50.0 million, or $0.64 per basic and diluted share, compared with a net loss of $38.8 million, or $0.62 per basic and diluted share, for the comparable period in 2013. The increase in net loss was due to higher research and development expenses, primarily as a result of an increase of $10.0 million in license fees paid to Array. The increase in net loss was also the result of higher general and administrative expenses and lower non-cash income from the change in fair value of warrant liability, which was $0.8 million for the year ended December 31, 2014 compared to $2.3 million for the year ended December 31, 2013.

Net loss for the three months ended December 31, 2014 was $27.6 million, or $0.30 per basic and diluted share, compared with a net loss of $6.4 million, or $0.09 per basic and diluted share, for the comparable period in 2013. The increase in net loss for the three months ended December 31, 2014 compared to the prior year period was primarily attributable to an upfront payment of $20.0 million to Array in December 2014 and lower non-cash income from the change in the fair value of warrant liability, which was $0.3 million for the three months ended December 31, 2014 compared to $1.2 million for the three months ended December 31, 2013.

As of December 31, 2014, Oncothyreon’s cash, cash equivalents and investments were $63.7 million, compared to $72.6 million at December 31, 2013, a decrease of $8.9 million, or 12.3 percent. The decrease was primarily attributable to $48.4 million of cash used in operations during the year ended December 31, 2014, partially offset by the net proceeds of $40.2 million from the closing of concurrent but separate underwritten offerings of Oncothyreon common stock and Series A convertible preferred stock in September 2014.

In February 2015, Oncothyreon closed additional concurrent but separate underwritten offerings of Oncothyreon common stock and Series B convertible preferred stock, resulting in net proceeds of 22.4 million.

Financial Guidance

Oncothyreon believes the following financial guidance to be correct as of the date provided. Oncothyreon is providing this guidance as a convenience to investors and assumes no obligation to update it.

Oncothyreon currently expects operating expenses in 2015 to be lower than in 2014, which included the upfront payment to Array for the exclusive license to ONT-380. Oncothyreon currently expects cash used in operations in 2015 to be approximately $35.0 - $38.0 million.

Conference Call and Webcast

Oncothyreon will conduct a conference call today, March 10, 2015 at 4:30 p.m. Eastern time (1:30 p.m. Pacific time) to discuss its full year and fourth quarter 2014 financial results and provide a review of its pipeline of products in development. To participate in the call by telephone, please dial (877) 280-7291 (United States) or (707) 287-9361 (International). In addition, the call will be webcast live and can be accessed on the “Events” page of the “News & Events” section of Oncothyreon’s website at www.oncothyreon.com. An archive of the webcast will be available after completion of the discussion and will be posted on Oncothyreon’s website.

About Oncothyreon

Oncothyreon is a biotechnology company specializing in the development of innovative therapeutic products for the treatment of cancer. Oncothyreon’s goal is to discover, develop and commercialize compounds that have the potential to improve the lives and outcomes of cancer patients. For more information, visit www.oncothyreon.com.

Forward-Looking Statements

In order to provide Oncothyreon’s 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 Oncothyreon’s expectations regarding future expenses and the use and adequacy of cash resources.

Forward-looking statements involve risks and uncertainties related to Oncothyreon’s business and the general economic environment, many of which are beyond its control. These risks, uncertainties and other factors could cause Oncothyreon’s 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 Oncothyreon 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 Oncothyreon’s 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. Oncothyreon 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 Oncothyreon can be found on EDGAR at www.sec.gov and on SEDAR at www.sedar.com.

Investor and Media Relations Contact:

Julie Rathbun

Rathbun Communications

206-769-9219

ir@oncothyreon.com

ONCOTHYREON INC. 2601 Fourth Avenue, Suite 500, Seattle, WA 98121

Tel: (206) 801-2100 Fax: (206) 801-2101

http://www.oncothyreon.com

ONCOTHYREON INC.

Consolidated Statements of Operations

(In thousands except share and per share amounts)

(Unaudited)

ONCOTHYREON INC.

Consolidated Balance Sheet Data

(In thousands except share amounts)

(Unaudited)