Last updated on April 16, 2014 at 21:24 EDT

Oncothyreon Announces Presentation of Data from Phase 1Trial of ONT-10

November 8, 2013

SEATTLE, Nov. 8, 2013 /PRNewswire/ – Oncothyreon Inc. (NASDAQ: ONTY) today
announced the presentation of preliminary results from an ongoing Phase
1 trial of ONT-10, a therapeutic vaccine targeting the tumor-associated
antigen MUC1, at the Annual Meeting of the Society for Immunotherapy of
Cancer in National Harbor, Maryland. The trial is a first-in-man dose
escalation trial in patients with advanced, previously treated
malignancies of types associated with the expression of MUC1. ONT-10
was administered either weekly or every other week over an 8 week
period. Patients with stable disease for at least twelve weeks after
starting treatment with ONT-10 were eligible for a separate maintenance
protocol in which the same dose of the vaccine was administered every
six weeks until tumor progression.

The dose escalation portion of the trial has enrolled 33 patients with
advanced malignancies, including ovarian cancer (10), pancreatic cancer
(5), endometrial cancer (4), colorectal cancer (4) lung cancer (3) and
breast cancer (3), who had received extensive prior lines of therapy
(median 3, range 1-11). ONT-10 was administered at doses from 250 µg
up to 1000 µg weekly, and from 250 µg up to 2000 µg every other week.
To date, 19 patients have entered the maintenance protocol. ONT-10 has
been well-tolerated in this trial, with no treatment-related serious
adverse events. The most common treatment-related adverse events have
been fatigue and injection site reactions, all of which have been mild
to moderate in severity. A dose-limiting toxicity has not been
identified, and patients are currently being enrolled in a 2000 µg
weekly cohort.

A significant endpoint of the trial was to determine if ONT-10
stimulates the production of MUC1-specific antibodies as seen in
preclinical animal models. At the time of the presentation, sera were
available for testing in 30 patients treated at doses up to 1000 µg
weekly. IgM and IgG anti-MUC1 antibodies were observed in the majority
of patients at titers frequently exceeding 1:50,000. The data support
a dose and schedule response, with the greatest IgG response occurring
at 1000 µg weekly.

Thirty-one patients were evaluated for anti-tumor activity by RECIST
(Response Evaluation Criteria in Solid Tumors) 1.1. Twenty patients
(65%) were progression free at the time of first tumor assessment at
week 9 or 10, while progressive disease occurred in 11 patients (35%).
Eight patients have been progression free for 6 months or greater
(range 6 to 18 months). Three of these 8 patients were reported to have
a history of progressive disease prior to the initiation of ONT-10,
while an additional patient had a rising tumor marker. A decrease in
the size of nodal disease was seen in two patients with ovarian cancer.

“Our early experience with ONT-10 is encouraging” said John Nemunaitis,
M.D. Executive Medical Director at Mary Crowley Cancer Research
Centers, Dallas, Texas and principal investigator for this study. “The
lack of observed toxicity, the immune response to the vaccine, and the
delayed time to progression of greater than 6 months in advanced stage
patients are all supportive of the expansion of ONT-10 into later stage

“We are excited by the strong antibody response to ONT-10 we have seen
in this trial,” said Scott Peterson, Ph.D. Chief Scientific Officer of
Oncothyreon. “In preclinical models treatment with ONT-10 was
associated with both a high titer antibody response and significant
anti-tumor activity. As our studies with ONT-10 progress, we are
looking forward to evaluating the correlation of antibody levels with
potential anti-tumor activity in man.”

“Upon completion of the dose-escalation portion of this trial, we
currently plan to enroll one or more disease-specific expansion
cohorts,” said Diana Hausman, M.D., Chief Medical Officer of
Oncothyreon. “We intend to use these results to guide our plans for
the further development of ONT-10.”

About ONT-10

ONT-10 is a therapeutic vaccine targeting MUC1, a tumor-associated
antigen present on many types of human malignant tumors, including
lung, breast, colorectal, prostate and ovarian cancer. ONT-10 contains
a glycosylated antigen designed to mimic the hypoglycosylated state of
tumor-associated MUC1 and intended to stimulate both the humoral and
cellular arms of the immune response. Preclinical results demonstrated
that administration of ONT-10 produces a robust antibody response in
mice specific for human tumor MUC1, a strong cellular immune response
directed to the target and significant anti-tumor activity.
Additionally, the adjuvant component of ONT-10, PET-Lipid A, a fully
synthetic toll like receptor 4 (TLR4) agonist discovered by
Oncothyreon, was shown to have enhanced potency compared to the
marketed adjuvant monophosphoryl lipid A (MPL®).

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.

SOURCE Oncothyreon Inc.

Source: PR Newswire