New data may help guide the clinical development of Biomira's PX-478 and PX-866
October 24 2007 - 8:00AM
PR Newswire (US)
EDMONTON, Oct. 24 /PRNewswire-FirstCall/ -- Biomira Inc.
(NASDAQ:BIOM) (TSX: BRA) announced today that preclinical data for
its targeted anti-cancer drug candidates PX-478 and PX-866 were
presented in a poster session yesterday at the AACR-NCI-EORTC
International Conference on Molecular Targets and Cancer
Therapeutics, which is being held October 22-26 in San Francisco.
The data may help to guide future clinical studies of these
innovative small molecule compounds. A Phase 1 trial of PX-478 in
patients with advanced metastatic cancers is in progress. Biomira
expects to file an Investigational New Drug application for PX-866
early in 2008. The PX-478 data (Abstract #284) provide insight into
how and under what conditions the compound inhibits the activity of
its target, the transcription factor hypoxia-inducible
factor-1alpha (HIF-1 alpha). PX-478 works by a unique mechanism,
decreasing both HIF-1 alpha gene expression and protein synthesis.
This leads to a significant reduction in the amount and activity of
HIF-1 alpha in the tumor. The results show that PX-478 is highly
specific for HIF-1 alpha and does not inhibit the levels of any of
the other proteins tested. Additionally, this inhibitory effect is
independent of the tumor suppressor genes VHL and p53, genes that
may significantly impact how cancer cells respond to a variety of
therapeutic interventions. "Hypoxia is a feature of many solid
tumors and HIF-1 alpha is the tumor's primary survival response to
this stress," said Dr. Garth Powis, Director, Center for Targeted
Therapy, MD Anderson Cancer Center, Houston, Texas, and senior
author of the abstract. "Inhibiting both transcription and
translation is a double hit that dramatically decreases the
activity of HIF-1 alpha, which regulates numerous pro-cancer
pathways. That this reduction in HIF-1a activity occurs in cells
regardless of oxygenation, p53 and VHL status suggests that PX-478
may have clinical activity in diverse cancers. The elucidation of
the mechanisms by which PX-478 inhibits HIF-1 alpha confirms the
compound's specificity and may aid the direction of the clinical
program with respect to identifying specific cancer indications and
potential combination regimens for this promising agent." A second
poster reported data from preclinical studies of PX-866, a small
molecule inhibitor of phosphatidylinositol-3-kinase (PI-3 kinase)
(Abstract #257). These studies evaluated mutations in several
cancer-related genes that could be predictive of response to PX-866
in animal tumor models. In a range of different tumor types,
response to PX-866 correlated with wildtype Ras, while mutations in
Ras were associated with PX-866 resistance. These results suggest
that selecting for patient Ras status could improve the clinical
benefit of PX-866. Dr. Powis noted, "Biomarkers that are predictive
of response to particular therapies are playing an increasingly
significant role in optimizing cancer treatment for individual
patients. The PX-866 biomarker data suggest that it may be possible
to identify those patients most likely to respond to the agent.
These data also provide insight into how we could combine PX-866
with other agents based on the molecular profiles of specific
cancers. Together, this knowledge may help to speed the clinical
development of this promising new PI-3 kinase inhibitor" Both
posters will be available later today on the Biomira website,
http://www.biomira.com/. About PX-478 PX-478 is a potent inhibitor
of HIF-1 alpha, a protein target whose levels are elevated in a
wide range of tumors. The protein is a key factor in the response
of a cancer cell to hypoxia (lack of oxygen), including the
angiogenic cascade that allows tumors to establish new blood
vessels essential to their survival and growth. Inhibition of
angiogenesis is a validated approach to treating cancer. In
preclinical studies, PX-478 demonstrated marked antitumor activity
when delivered orally, showing tumor regression and long growth
delay, both of which correlated to the HIF-1 alpha levels of the
tumor models. The wide variety of models that showed sensitivity to
PX-478 presents a large potential market for this product
candidate. The ability to combine PX-478 with radiation therapy may
further expand the opportunities for this novel compound. About
PX-866 PX-866 is an irreversible inhibitor of the
phosphatidylinositol-3-kinase (PI3 kinase)/PTEN/AKT pathway, an
important survival signaling pathway that is activated in many
types of human cancer especially ovarian, colon, head and neck,
urinary tract, and cervical cancers, where it leads to increased
proliferation, inhibition of apoptosis (programmed cell death) and
resistance to antitumor therapy. In preclinical studies, PX-866 has
been shown to induce prolonged inhibition of tumor PI3 kinase
signaling following both oral and intravenous administration. The
compound also has been shown to have good in vivo anti-tumor
activity in tumor models of human colon, pancreatic, breast,
ovarian, prostate and lung cancer, as well as intracranial
glioblastoma. About Biomira Biomira is a biotechnology company
specializing in the development of innovative therapeutic products
for the treatment of cancer. Biomira'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. Forward-Looking Statements This press release contains
forward-looking statements, including, without limitation,
statements related to the pre-clinical and clinical development of
PX-478 and PX-866; the therapeutic and commercial potential of
PX-478 and PX-866; the filing of an investigational new drug
application for PX-866 and the timing thereof; and future clinical
development plans. 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
express Biomira's current expectations, intentions, plans and
forecasts of future events based on our experience and our
assessment. Forward-looking statements involve risks and
uncertainties. Various factors could cause actual results to differ
materially from those projected in forward-looking statements,
including those predicting relevance of pre-clinical data to the
subsequent clinical development of PX-478 and PX-866; the clinical
development of PX-478 and PX-866; the therapeutic and commercial
potential of PX-478 and PX-866; the filing of an investigational
new drug application for PX-866 and the timing thereof; and future
clinical development plans. There can be no guarantee that the
results of earlier trials will be predictive of either safety or
efficacy in future trials. Biomira expressly disclaims any
obligation or undertaking to release publicly any updates or
revisions to any forward-looking statements contained herein to
reflect any change in the Company's expectations with regard
thereto or any change in events, conditions or circumstances on
which any such statements are based. DATASOURCE: Biomira Inc.
CONTACT: Investor and Media Relations Contact: Julie Rathbun,
Rathbun Communications, (206) 769-9219,
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