Oncothyreon Announces Initiation of Phase 1 Trial of ONT-380 in Combination with Trastuzumab in Patients with Brain Metastases

 Oncothyreon Announces Initiation of Phase 1 Trial of ONT-380 in Combination
 with Trastuzumab in Patients with Brain Metastases from HER2+ Breast Cancer

PR Newswire

SEATTLE, WA, Sept. 3, 2013

SEATTLE, WA,  Sept. 3,  2013 /PRNewswire/  - Oncothyreon  Inc. (NASDAQ:  ONTY) 
today announced the initiation of  an investigator-sponsored trial of  ONT-380 
in combination with trastuzumab (Herceptin®) in patients with brain metastases
from HER2+ breast cancer. The trial is being conducted under the  sponsorship 
of the  Dana-Farber Cancer  Institute, Boston,  Massachusetts. 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., Boulder, Colorado.

The Phase  1 trial  is a  dose-escalation trial  in up  to 50  patients.  The 
primary objectives are to determine the maximum-tolerated dose and recommended
Phase 2  dose and  schedule  of ONT-380  in  combination with  trastuzumab  in 
patients  with  HER2+   breast  cancer  and   central  nervous  system   (CNS) 
metastases. Secondary objectives include CNS objective response rate by  both 
RECIST  and  volumetric  criteria,   progression-free  survival  and   overall 
survival. The study  will be  conducted in two  parallel arms  with two  dose 
regimens of ONT-380,  either once-daily  or twice-daily,  in combination  with 
standard dose trastuzumab.

"ONT-380 has  demonstrated  superior  activity,  based  on  overall  survival, 
compared to Tykerb^® (lapatinib) and  to the investigational drug,  neratinib, 
in an  intracranial  HER2+ breast  cancer  xenograft model,"  said  Robert  L. 
Kirkman, M.D.,  President and  CEO  of Oncothyreon.  "This provides  a  strong 
rationale to  explore whether  ONT-380 can  provide benefit  to patients  with 
brain metastases, and we are pleased that the Dana Farber Cancer Institute  is 
undertaking this trial."

"CNS metastases, which occur in one-third to one-half of women with metastatic
HER2+ breast cancer,  remain a  significant clinical problem,"  said Nancy  U. 
Lin, M.D., Principal Investigator of the Phase 1 trial and Clinical  Director, 
Breast Oncology, Dana-Farber Cancer Institute.  "There is an urgent need  for 
new therapies to treat patients with brain metastases from breast cancer,  and 
we are excited to begin this study of ONT-380".

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 and  Tykerb. 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).

A  Phase  1  trial  of  ONT-380,  with  both  dose-escalation  and   expansion 
components, has been completed in 50 patients, 43 of whom had HER2+ metastatic
breast  cancer.  All  HER2+  breast  cancer  patients  had  progressed  on   a 
trastuzumab-containing regimen. In  addition, over 80%  had been treated  with 
lapatinib, with  many having  progressed on  therapy. 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.  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 (BID).  Twenty-two 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.

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 

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 

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.


Investor and Media Relations Contact:

Julie Rathbun
Rathbun Communications
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