News Release

Onconova to present clinical trials update on ON 01910.Na at American Society of Hematology Meeting

Results with Estybon (ON 01910.Na) in Patients with myelodysplastic syndromes; ON 013105 cyclin D1 inhibitor active in models of mantle cell lymphoma

Peer-Reviewed Publication

PR on Call

NEWTOWN, PA and PRINCETON, NJ Dec. 3, 2010 / PRNewswire-FirstCall / Onconova Therapeutics announces its late-stage anticancer agent, Estybon® (ON 01910.Na), will be featured in three presentations at the 52nd American Society of Hematology (ASH) Annual Meeting in Orlando, FL, December 4-7, 2010.

Principal investigators at four centers, Dr. Lewis Silverman (Mount Sinai Medical Center), Dr. Azra Raza (Columbia University Medical Center), Dr. Elaine Sloand (NHLBI), and Dr. Peter Greenberg (Stanford University Medical Center) report that in 48 higher risk patients with MDS or AML (who failed or became resistant to previous drug treatments), when treated with ON 01910.Na showed increases in overall survival, which correlated with bone marrow blast responses. The most dramatic improvement in overall survival was seen in 19 patients who also showed either bone marrow complete response (CR) or initial >50% decrease in blast cells (Abstract #3998). Dr. Greenberg's team reports encouraging efficacy and drug tolerance results in a Phase II trial with patients who had all failed the standard hypomethylating agent treatments (Abstract #4010). Dr. Silverman and colleagues have observed 50% responders in a Phase I study (Abstract #2944).

Estybon® (ON 01910.Na) is a small molecule, targeted therapeutic with a broad spectrum of activity. It has been tested in patients with solid tumors, myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) at major centers in the U.S. and abroad. MDS and AML are blood disorders widely recognized as difficult to manage, with limited therapeutic options for patients, especially those with drug-resistant disease. The presentations will describe the latest results on activity and safety of Estybon® (ON 01910.Na) in MDS and AML patients treated in on-going Phase I and Phase II clinical trials.

These studies are a part of comprehensive evaluation of the safety and activity of Estybon® (ON 01910.Na). To date, nearly 300 cancer patients have been treated in Phase I and Phase II trials, including more than 70 patients with MDS or AML. These studies have lead to a multi-site Phase III pivotal trial under a Special Protocol Assessment (SPA) from the U.S. FDA. This trial is being supported by an award from the Therapeutics Acceleration Program (TAP) of the Leukemia and Lymphoma Society (LLS).

"We continue to make meaningful progress in our MDS program, and information to be presented at the ASH meeting reflects the breadth of data becoming available for ON 01910.Na in MDS patients," said Francois Wilhelm, MD, PhD, Senior Vice President and Chief Medical Officer of Onconova. "We are committed to the rapid development of this promising agent for MDS patients by conducting a multi-site trial in the United States and France," Dr. Wilhelm added.

Another presentation will highlight the mechanism of action and activity in nonclinical models of mantle cell lymphoma (MCL) of ON 013105, a novel Onconova agent directed to controlling Cyclin D1 in cancer cells (Abstract #771). ON 013105 alone or in combination with rituximab induced dramatic reduction of MCL tumor volumes in mouse xenograft models, suggesting that ON 013105 alone or in combination may be a potent therapeutic agent against MCL. ON 013105 is currently in Phase I clinical safety studies in lymphoma patients.

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About ESTYBON

Estybon® (ON 01910.Na), is a small molecule inhibitor of critical pathways important in the growth and proliferation of cancer cells. Extensive Phase I and Phase II studies with Estybon® have been conducted in patients with solid tumors and hematological cancers, including MDS and AML, where more than 70 patients have been enrolled in studies conducted at four leading institutions in the U.S. FDA has granted Orphan Drug Designation for the use of Estybon® in MDS. A U.S. Patent covering ON 01910.Na issued in October 2009 and international patent coverage is expected.

About Onconova Therapeutics, Inc.

Onconova, based in Newtown, PA and Princeton, NJ, discovers and develops novel small molecule therapeutics with fully differentiated targets involved in signal transduction, cell-cycle, and DNA repair. These candidates are derived from a proprietary library of new chemical entities and non-ATP competitive chemotypes. In addition to Estybon® (ON 01910.Na) and ON 013105, Onconova is also developing Ex-RAD®, an injectable and oral radioprotectant. The oncology preclinical pipeline at Onconova includes inhibitors of Plk2, ALK, CDK, JAK, and Bcr-Abl pathways and a novel immunoconjugate platform for arming therapeutic antibodies. Currently, Onconova is conducting clinical trials at major centers in the U.S. and abroad for three product candidates. For additional information, please visit http://www.onconova.com.

Summary of ASH Presentations Relating to Estybon® (ON 01910.Na) and ON 013105

Sunday, December 5:
Session: Myelodysplastic Syndromes Poster II, Hall A3/A4 (Orange County Convention Center)

Poster Board # II-824
Abstract #2944
"Evaluation of ON 01910.Na in Patients with a Myelodysplastic Syndrome (MDS) or Acute
Myeloid Leukemia (AML) Relapsed or Refractory to Hypomethylating Agents: A Phase I Study"
Lewis R Silverman, Shyamala C. Navada, Rosalie Odchimar-Reissig, Vesna Najfeld, Takao Ohnuma, Francois Wilhelm, E. Premkumar Reddy, James F. Holland; Division of Hematology/Oncology, Mount Sinai School of Medicine, New York, NY; Mount Sinai School of Medicine, New York, NY; Onconova Therapeutics, Inc., Newtown, PA

Monday, December 6:
Session: Myelodysplastic Syndromes Poster III, Hall A3/A4 (Orange County Convention Center)

Poster Board # III-777
Abstract #3998
"Overall Survival in Patients with a Myelodysplastic Syndrome or Acute Myeloid Leukemia Treated With ON 01910.Na Correlates with Bone Marrow Blast Response"
Lewis R. Silverman, Azra Raza, Elaine Sloand, Peter L. Greenberg, Francois Wilhelm; Mount Sinai Medical Center, New York, NY, Columbia University Medical Center, New York, NY, National Heart, Lung and Blood Institute, Bethesda, MD, Stanford University Cancer Center, Stanford, CA, Onconova Therapeutics, Inc., Newtown, PA

Poster Board # III-789
Abstract #4010
"Treatment of Higher Risk Myelodysplastic Syndrome Patients Unresponsive to Hypomethylating Agents with ON 01910.Na"
Mahesh Seetharam, Mai Tran, Alice C. Fan, Liwen Xu, John P. Renschler, Dean W. Felsher, Kunju Sridhar, Francois Wilhelm, Peter L. Greenberg; Departments of Medicine (Hematology) and Medicine (Oncology), Stanford University Cancer Center, Stanford, CA;, Onconova Therapeutics Inc., Newtown, PA

Session: Lymphoma/Pre-Clinical/Chemotherapy and Biologic Agents: Preclinical Advances in Mantle Cell Lymphoma (Oral Presentations); Session Time 4:30 - 6:00 PM; Room 308 (Orange County Convention Center)

Presentation Time: 5:00 PM
Abstract #771
"Synergistic Effects of a Novel Water-soluble Small Molecule, ON 013105, and Rituximab on Mantle Cell Lymphoma In vitro and In vivo"
Anil Prasad, Ashutosh Shrivastava, Ramana MV Reddy, Amanda Gillum, E. Premkumar Kumar Reddy, Jerome Groopman: Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA; Department of Oncological Sciences, Mount Sinai School of Medicine, New York, NY, Onconova Therapeutics, Inc., Newtown, PA


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