Tumors Stayed Stable or Decreased in Size in Nearly All Melanoma Patients
Phase I Studies Show Median Survival Rate of 13 Months
Corporate Partnership Expected by Year-end
SAN MATEO, Calif., March 23, 2010 (GLOBE NEWSWIRE) -- Pain Therapeutics, Inc. (Nasdaq:PTIE) today announced encouraging clinical data with PTI-188, an early-stage drug for metastatic melanoma. Metastatic melanoma is a lethal form of skin cancer in which patients typically have a median survival time of 9 months.
Although efficacy was not a primary endpoint, PTI and its clinical investigators were encouraged by the number of melanoma tumors that had either stabilized or decreased in size after a single dose of PTI-188. In a first Phase I study with PTI-188, most patients (nearly 70%) showed stable disease in target lesions at the conclusion of the six-week study. In a second Phase I study, approximately 40% of patients showed stable disease at week fourteen. Preliminary analysis, combining both clinical studies, indicates a median overall survival time of 13 months (n=19).
Pain Therapeutics' PTI-188 is a proprietary, radio-labeled monoclonal antibody. It is designed to locate and bind to melanoma tumors inside the body, and to deliver a powerful dose of radiation to tumor sites. This radiation destroys cancer cells, thus promoting anti-tumor activity. Pain Therapeutics holds exclusive worldwide, commercial rights to PTI-188.
"There is no satisfactory treatment for metastatic melanoma," said Arturo Casadevall, MD, PhD, Professor of Microbiology and Immunology and Medicine, Albert Einstein College of Medicine. "PTI-188 is very promising because its approach to treatment is completely different from current attempts to treat this disease. Its unique activity could significantly improve survival for patients with metastatic melanoma."
"We are excited by the evidence of tumor targeting seen with PTI-188," said Michal Lotem, MD, Principal Investigator and Head, Center for Melanoma and Cancer Immunotherapy, Hadassah Hebrew University Medical Center. "This experimental treatment may exert its beneficial effects by direct tumor hit and by changing the tumor's microenvironment, including the feeding blood vessels and supportive cells. Further studies with PTI-188 are of the highest priority."
"Our clinical data in melanoma is encouraging and much work remains," said Remi Barbier, Chairman, President & CEO of Pain Therapeutics. "We intend to stick to our strategy to spend carefully but to keep innovation at the top of our agenda. To balance these competing goals, we expect to sign a worldwide R&D and commercial partnership for PTI-188 by year-end."
Phase I Dose-Escalating Studies
Two open-label, dose-escalating Phase I studies were conducted in Israel to assess the safety, pharmacokinetics, dosimetry and anti-tumor activity of PTI-188. A total of 19 patients were enrolled with confirmed Stage IV or unresectable Stage III melanoma, the worst forms of melanoma disease. All patients were treated with a single intravenous dose of PTI-188. Anti-tumor effects were measured by RECIST (Response Evaluation Criteria in Solid Tumors) at baseline, post-treatment at weeks two and six, and monthly thereafter. Among evaluable patients to date, top-line results confirm the preliminary safety and biological activity of PTI-188, within the confines of two Phase I studies:
- Based on the safety profile and dosimetry to normal organs, PTI-188 was well tolerated at all doses, suggesting these studies did not reach the maximum tolerated dose.
- In a first Phase I study with PTI-188, most patients (nearly 70%) met the RECIST criteria for stable disease in target lesions at the conclusion of the six-week study.
- In a second Phase I study with PTI-188, approximately 40% of patients met the RECIST criteria for stable disease at week 14.
- In the second Phase I study, five of seven patients were still alive an average of 26 months from initial diagnosis of Stage III/IV melanoma through disease progression following a single dose of PTI-188, with a range of 8 to 68 months. Preliminary analysis, combining both clinical studies, indicates a median overall survival of 13 months (n=19).
- Target tumors were observed to stay stable or decrease in size in nearly all patients.
- Drug-related adverse events were predominantly mild in severity. No drug-related serious adverse events were observed in these studies.
About PTI-188
PTI-188 is a monoclonal antibody labeled with rhenium-188, a radioactive isotope. The labeled antibody binds to extracellular (but not intracellular) melanin released during tumor cell turnover. Atoms from the radio-isotope emit particles capable of destroying cancerous tumors extremely efficiently, thus promoting anti-tumor activity and tumor regression. Importantly, PTI-188 is intended to treat all forms of metastatic melanoma, regardless of genetic mutations. For more technical information, please see: http://www.paintrials.com/publications/PNAS.pdf
About Metastatic Melanoma
Metastatic melanoma is a lethal form of skin cancer. According to the American Cancer Society, over 8,000 people in the United States died of melanoma during 2009. If diagnosed early and surgically removed, early-stage melanoma is potentially curable. However, the advanced form of this cancer, or metastatic melanoma, has a poor prognosis and limited treatment options. Metastatic melanoma patients have a median survival time of 9 months and a 5-year survival rate of about 3%. There has been little change in these results in the past 25 years.
About Pain Therapeutics, Inc.
Pain Therapeutics, Inc. is a biopharmaceutical company that develops novel drugs. In addition to REMOXY®, a unique abuse-resistant controlled-release oxycodone, we have three drug candidates in clinical programs, including PTI-188 to treat metastatic melanoma. We are also working on a new treatment for patients with hemophilia. For more information, please visit www.paintrials.com.
Note Regarding Forward-Looking Statements: This press release contains forward-looking statements for purposes of the Private Securities Litigation Reform Act of 1995 (the "Act"). Pain Therapeutics disclaims any intent or obligation to update these forward-looking statements, and claims the protection of the Safe Harbor for forward-looking statements contained in the Act. Examples of such statements include, but are not limited to, expected timing of completion of corporate partnership around PTI-188; the ability of PTI-188 to improve the survival rate for metastatic melanoma patients and other potential benefits of the Company's drug candidates. Such statements are based on management's current expectations, but actual results may differ materially due to various factors. Such statements involve risks and uncertainties, including, but not limited to, those risks and uncertainties relating to difficulties or delays in development and testing of PTI-188, unexpected adverse side effects or inadequate therapeutic efficacy of PTI-188 (including the risk that current and past results of clinical trials and non-clinical testing are not necessarily indicative of future results of clinical trials), the uncertainty of patent protection for the Company's intellectual property or trade secrets, the potential for competitive products and therapies that may be developed by others. For further information regarding these and other risks related to the Company's business, investors should consult the Company's filings with the Securities and Exchange Commission.