Oncothyreon Announces Presentation of Final Results from Phase 1 Trial of ONT-380

  Oncothyreon Announces Presentation of Final Results from Phase 1 Trial of
                                   ONT-380

PR Newswire

SEATTLE, WA, Oct. 7, 2013

SEATTLE, WA, Oct. 7, 2013 /PRNewswire/ - Oncothyreon Inc. (NASDAQ: ONTY) today
announced the presentation of final results from the first Phase 1 trial of
ONT-380 at the American Association for Cancer Research Special Conference on
Advances in Breast Cancer Research in San Diego. The results were presented
by Virginia F. Borges, M.D., Associate Professor in the Division of Medical
Oncology, University of Colorado School of Medicine. ONT-380 (also known as
ARRY-380) is an orally active, reversible and selective small-molecule HER2
inhibitor being developed by Oncothyreon in collaboration with Array BioPharma
Inc. (Nasdaq: ARRY), Boulder, Colorado.

The first-in-human  Phase 1  trial, with  both dose-escalation  and  expansion 
components, enrolled a total of 50  patients, 43 of whom had HER2+  metastatic 
breast cancer.  In  this study,  ONT-380  demonstrated an  acceptable  safety 
profile; treatment-related  adverse events  were primarily  Grade 1.  Because 
ONT-380 is selective  for HER2  and does  not inhibit  EGFR, there  was a  low 
incidence and severity of treatment-related  diarrhea, rash and fatigue,  side 
effects which have  been associated  with EGFR inhibition.  A single  patient 
experienced Grade  2  treatment-related  diarrhea  and  no  patient  developed 
treatment-related  Grade  3  diarrhea;  one  patient  had  a  Grade  3   rash. 
Additionally, there  were  no  treatment-related cardiac  events  or  Grade  4 
treatment-related adverse  events  reported.  The maximum  tolerated  dose  of 
ONT-380 established  in  this Phase  1  trial was  600  mg twice  daily.  The 
dose-limiting toxicity was reversible elevation in liver enzymes.

In this trial, 22  HER2+ breast cancer patients  with measurable disease  were 
treated with ONT-380 at  doses greater than  or equal to 600  mg BID. In  this 
heavily pretreated  patient  population, there  was  a clinical  benefit  rate 
(partial response [n = 3] plus stable disease  for at least 6 months [n =  3]) 
of 27%. Notably, two of the  patients with partial responses during  treatment 
with  ONT-380  had  confirmed  progressions  while  on  prior  lapatinib-  and 
trastuzumab-containing regimens.

"We believe that ONT-380's selectivity for HER2, without also targeting  EGFR, 
positions ONT-380 as a potential best-in-class small molecule HER2 inhibitor,"
said Robert  L.  Kirkman,  M.D.,  President and  Chief  Executive  Officer  of 
Oncothyreon. "Results  from  this first-in-human  trial  provide  preliminary 
evidence of  activity against  HER2+ breast  cancer with  a low  incidence  of 
EGFR-related side  effects.  We are  looking  forward to  the  initiation  of 
Oncothyreon's planned Phase 1b trials of ONT-380, which we currently expect to
begin before year end."

About ONT-380

ONT-380 is  an orally  active,  reversible and  selective HER2  inhibitor.  In 
multiple preclinical tumor models, ONT-380 was well tolerated and demonstrated
significant  dose-related  tumor  growth  inhibition  that  was  superior   to 
Herceptin® (trastuzumab)  and  Tykerb®  (lapatinib).  Additionally,  in  these 
models, ONT-380 demonstrated synergistic  or additive tumor growth  inhibition 
when dosed in combination with the standard-of-care therapeutics Herceptin  or 
Taxotere® (docetaxel). ONT-380 has also demonstrated superior activity,  based 
on overall survival, compared  to lapatinib and  to the investigational  drug, 
neratinib, in an intracranial HER2+ breast cancer xenograft model.

Under the collaboration  agreement with  Array, Oncothyreon  will conduct  the 
clinical  development  of  ONT-380  through  a  defined  set  of   combination 
proof-of-concept trials in patients  with metastatic breast cancer,  including 
patients with brain metastases. Oncothyreon currently expects to initiate its
clinical development of ONT-380 in the  fourth quarter of 2013. In  addition, 
an investigator-sponsored trial of ONT-380 in combination with trastuzumab  in 
patients with  brain metastases  from HER2+  breast cancer  is underway.  The 
trial is  being conducted  under  the sponsorship  of the  Dana-Farber  Cancer 
Institute, Boston, Massachusetts.

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  develop and  commercialize novel synthetic  vaccines and  targeted 
small molecules 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 clinical  development 
activities.

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  those predicting  the timing,  duration 
and results of clinical trials, the timing and results of regulatory  reviews, 
the safety and  efficacy of our  product candidates, and  the indications  for 
which our product  candidates might be  developed. There can  be no  guarantee 
that the results of preclinical studies or clinical trials will be  predictive 
of either safety or efficacy  in future clinical trials. 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.

SOURCE Oncothyreon Inc.

Contact:

Investor and Media Relations Contact:
Julie Rathbun
Rathbun Communications
206-769-9219
ir@oncothyreon.com
 
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