Oncothyreon's ONT-10, PX-866 preclinical data presented at AACR meeting

Oncothyreon Inc. (Nasdaq: ONTY) today announced the presentation of preclinical data for ONT-10, a therapeutic vaccine directed at cancers expressing MUC1, and PX-866, its irreversible inhibitor of phosphatidylinositol 3-kinase (PI3K), at the American Association of Cancer Research meeting in Orlando, Florida.

ONT-10

ONT-10 is a therapeutic vaccine targeting MUC1 which has been designed to stimulate both the humoral and cellular arms of the immune response.  Results presented at the meeting demonstrated that administration of ONT-10 produced a robust antibody response in mice that was specific for human tumor MUC1.  A strong cellular immune response directed to the target was also shown.  ONT-10 blocked the growth of two different tumors expressing human MUC1 in murine models, with a high proportion of animals tumor free at the conclusion of the experiment.  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 adjuvant monophosphoryl lipid A (MPL).

"These preclinical data validate our hypothesis that the antigen present in ONT-10 stimulates both effector arms of the immune response," said Scott Peterson, Ph.D., Vice President of Research and Development at Oncothyreon.  "We are looking forward to beginning our first clinical trial with ONT-10 late this year with a goal of replicating these data in man."

PX-866

PX-866 is an oral, small molecule compound designed to inhibit the activity of PI3K, a component of an important cell survival signaling pathway. Data presented at the meeting concerned the efficacy of PX-866 alone or in combination with either docetaxel or cetuximab in direct patient human tumor xenograft models (DPTM) of squamous cell carcinoma of the head and neck (SCCHN) developed by Dr. Antonio Jimeno's laboratory at University of Colorado School of Medicine.  These models maintain the histology of the tumor and are particularly suited to preclinical evaluation of novel cancer therapeutics.  PX-866 was equal or superior to docetaxel in slowing tumor growth in two of four DPTM and equal or superior to cetuximab in each of four DPTM. The combination of PX-866 plus docetaxel was superior to single agent therapy in three of four DPTM, while the combination with cetuximab was superior to single agent therapy in two of four DPTM.  The data were presented by Daniel W. Bowles, M.D., University of Colorado School of Medicine, Aurora, Colorado.

"These data are strongly supportive of our ongoing Phase 1/2 trials of PX-866 in combination with either docetaxel or cetuximab," said Diana Hausman, M.D., Vice President of Clinical Development at Oncothyreon. "The Phase 2 portion of each of these trials includes an arm enrolling patients with SCCHN."