Last updated on April 16, 2014 at 12:50 EDT

Oncothyreon Announces Presentation of PX-866 Clinical Data at American Association of Clinical Oncology Annual Meeting

June 2, 2012

SEATTLE, June 2, 2012 /PRNewswire/ – Oncothyreon Inc. (Nasdaq: ONTY) today
announced that data from two clinical trials of PX-866, a pan-isoform
phosphatidylinositol-3-kinase (PI-3K) inhibitor, were presented today
at the American Society of Clinical Oncology (ASCO) meeting in
Chicago.  Oncothyreon also provided an update on the status of its
ongoing Phase 2 development program for PX-866.

Phase 1 Trial of PX-866 in Combination with Docetaxel

Data from the Phase 1 portion of the ongoing Phase 1/2 of PX-866 in
combination with the chemotherapeutic agent docetaxel (Taxotere®) were
presented by Antonio Jimeno, M.D., Ph.D., of the University of
Colorado Cancer Center, Aurora, Colorado.  The trial enrolled 43
patients with advanced cancer for whom docetaxel was considered
standard of care. Patients were treated at three different dose levels
of PX-866 administered daily in combination with the standard dose of
docetaxel (75 mg/m(2)) administered once every three weeks. No dose-limiting toxicities were
identified, and the recommended Phase 2 daily dose of PX-866 to be
given in combination with docetaxel was determined to be the same as
the single agent daily maximum tolerated dose of 8 mg.

The combination of PX-866 and docetaxel was generally well-tolerated,
with most adverse events being mild to moderate in severity. The safety
profile for combination treatment was consistent with that for either
drug administered alone. Combination treatment had no impact on the
pharmacokinetic profile of either drug.

Thirty-three patients were evaluable for response, defined as having
undergone at least two cycles of therapy and a follow-up tumor
assessment.  In these patients, the disease control rate (partial
response or stable disease) was 85 percent (28/33) after two cycles of
therapy and 58 percent (19/33) after four cycles.  Ten patients were on
study for more than 200 days, five of whom remained on therapy at the
time of the report.  Nine patients with stable disease or better
discontinued docetaxel after four or more cycles and continued on
single agent PX-866, including all five remaining on therapy.  No
statistically significant differences in progression-free survival were
identified for patients with PIK3CA mutations or PTEN deficiency.

Phase 2 Trial of PX-866 in Patients with Glioblastoma Multiforme

Interim data from an open-label single-arm Phase 2 trial of PX-866 in
patients with glioblastoma multiforme (GBM), a type of brain cancer,
were presented by Marshall W. Pitz, M.D., of CancerCare Manitoba,
University of Manitoba, Winnipeg, Manitoba. The Phase 2 trial is being
conducted at 7 Canadian centers by the NCIC Clinical Trials Group (NCIC
CTG), Queen’s University in Kingston, Canada, in patients whose brain
tumor is in first relapse during or following primary therapy.  The
trial has a two-stage design, with progression to the second stage
dependent upon achieving a pre-specified endpoint of response or lack
of early progression.

Seventeen patients were enrolled in the first stage of the trial and
were included in this presentation.  PX-866 was well-tolerated in the
study, with the most common adverse events being diarrhea and
reversible liver enzyme elevation.  All patients were evaluable for
response, with one patient having a partial response and six patients
with stable disease, three of whom remained on therapy at the time of
the report.  These efficacy data met the pre-specified endpoint, and
the trial is currently enrolling a planned additional 15 patients in
the second stage.

PX-866 Phase 2 Program Update

In addition to the above mentioned trial in patients with GBM, the NCIC
CTG is also conducting a Phase 2 trial in up to 40 patients with
metastatic or recurrent castration resistant prostate cancer who have
not received prior chemotherapy.  The primary endpoint of this
single-arm screening trial is the proportion of patients with lack of
disease progression at 12 weeks from the initiation of therapy with
PX-866. The trial has a two-stage design, with progression to the
second stage dependent upon achieving a pre-specified endpoint of lack
of early progression.  The trial has completed enrollment in the first
stage of the study and the interim analysis is currently pending.

The Phase 1/2 trial of PX-866 in combination with docetaxel mentioned
above has advanced to the Phase 2 portion, which is an open-label,
randomized evaluation of the antitumor activity and safety of PX-866
administered at the recommended daily dose in combination with
docetaxel, versus docetaxel alone, in two groups of patients.  Group 1
is enrolling patients with non-small cell lung cancer (NSCLC) receiving
second or third line treatment. Group 2 is enrolling patients with
locally advanced, recurrent or metastatic squamous cell carcinoma of
the head and neck (SCCHN) after failure of prior therapy. The two
groups will be randomized and evaluated independently.   Enrollment of
a planned 88 patients in the NSCLC group is currently expected to be
completed this month.  Additional centers are being added to the SCCHN
arm of the trial, with a goal to complete enrollment of 82 patients in
the first half of 2013.

Oncothyreon has also advanced to the Phase 2 portion of a Phase 1/2
trial of PX-866 in combination with the chimeric monoclonal antibody
cetuximab (Erbitux®), which is an open-label, randomized evaluation of
the antitumor activity and safety of PX-866 administered at the
recommended daily dose in combination with cetuximab, versus cetuximab
alone, in two groups of patients .  Group 1 is enrolling patients with
metastatic colorectal cancer (CRC) who have a history of progression or
recurrence following prior treatment with irinotecan and oxaliplatin
containing regimens or who are intolerant of irinotecan.  Over 50 of a
planned 80 patients are currently enrolled in this arm of the trial,
with enrollment currently expected to be completed in the fourth
quarter of 2012. Group 2 is currently enrolling patients with incurable
progressive, recurrent or metastatic SCCHN. The two groups will be
randomized and evaluated independently.

Oncothyreon also recently announced the initiation of a Phase 1/2 trial
of PX-866 in combination with vemurafenib (Zelboraf®).  The Phase 1
portion of this trial will evaluate the safety and tolerability of
PX-866 in combination with twice daily oral administration of
vemurafenib in up to 36 patients with any BRAF-mutant cancer.  The
Phase 2 portion of the trial will compare the anti-tumor activity and
safety of PX-866 and vemurafenib at the doses recommended from Phase 1
with vemurafenib alone administered at the approved dose.  This
randomized Phase 2 trial is expected to enroll 110 patients with
advanced BRAF-mutant melanoma and has a primary endpoint of
progression-free survival.  This Phase 1/2 trial is being conducted in
collaboration with the Melanoma Research Foundation Breakthrough
Consortium (MRFBC).

About PX-866

PX-866 is a pan inhibitor of the PI-3K/PTEN/AKT pathway, a critical cell
signaling pathway that is activated in many types of human cancer.
Aberrant activation and regulation of PI-3K is implicated in a large
proportion of human cancers, where it leads to increased proliferation
and inhibition of apoptosis (programmed cell death).

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 intentions and future prospects, this release contains
statements that are forward looking, including statements related to
future clinical development plans for our product candidates. These
forward-looking statements represent Oncothyreon’s intentions, plans,
expectations and beliefs and are based on its management’s experience
and assessment of historical and future trends and the application of
key assumptions relating to future events and circumstances.

Forward-looking statements involve risks and uncertainties, including
risks and uncertainties related to Oncothyreon’s business and the
general economic environment. Many of these risks and uncertainties are
beyond Oncothyreon’s control. These risks, uncertainties and other
factors could cause our actual results to differ materially from those
projected in forward-looking statements. Risks, uncertainties, and
assumptions include 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. These and other risks and uncertainties are described in the
reports and other documents filed by Oncothyreon Inc. with the SEC
and/or Canadian regulatory authorities.

Although Oncothyreon believes that any 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 the risks and uncertainties associated with
Oncothyreon, you are encouraged to review the official corporate
documents filed with the securities regulators in the United States on
U.S. EDGAR and in Canada on SEDAR. Oncothyreon is under no obligation
to (and expressly disclaims any such obligation to) update or alter its
forward-looking statements whether as a result of new information,
future events, or otherwise.

SOURCE Oncothyreon Inc.

Source: PR Newswire