Encouraging Results Seen in Clinical Trial of Novel Skin Cancer Treatment

June 26, 2008 — (BRONX, NY) — Pain Therapeutics, Inc. recently announced the successful completion of its first clinical study utilizing a novel melanoma treatment, which the company licensed from Albert Einstein College of Medicine of Yeshiva University. The treatment consisted of dosing patients with a monoclonal antibody labeled with a radioisotope.

A research team at Einstein, led by Arturo Casadevall, M.D., Ph.D., professor and chairman of microbiology & immunology, and Ekaterina Dadachova, Ph.D., associate professor of nuclear medicine and of microbiology & immunology, developed the novel approach to treat metastatic melanoma based on targeting melanin, a skin pigment that is released from dead melanotic tumor cells, with radiolabeled monoclonal antibodies. While the antibodies seek out the released melanin and destroy human melanoma cells with a lethal dose of ionizing radiation, melanin in normal, healthy tissue is not targeted because it is inside the cells and not accessible to the radio-labeled antibody. Small animal studies have demonstrated the feasibility of this approach.

In the recent clinical study, a team of researchers in Israel administered the radiolabeled monoclonal antibody to 12 patients diagnosed with advanced melanoma. Top-line results of this Phase I study indicate this antibody binds to melanoma tumor sites, as evidenced by powerful imaging data obtained by planar scintigraphy and SPECT/CT (single photon emission computed tomography combined with computed tomography). No serious drug-related, adverse events were observed in this study.

"Our initial findings demonstrated how basic research in one area of medicine can yield unexpected benefits for an entirely different field," said Dr. Casadevall. "We didn't set out to find a cure for melanoma. Instead, the advance emerged from my study of Cryptococcus, a fungus that can cause fatal infections in people with weakened immune systems and evolved from there. It is exciting when findings take such a promising turn and we are thrilled that this first clinical study using our monoclonal antibody has met with the success that it has thus far."

"Going from the laboratory to clinical application is what we researchers strive to do so that physicians and their patients can be offered more and better options for treatment," said Dr. Dadachova. "It is among the most rewarding aspects of conducting research and we are grateful to Pain Therapeutics and our colleagues at Hadassah Medical Center for their efforts to determine how useful this treatment can possibly be. We have great hopes for further success."

The objectives of the first Phase I study were to assess safety, pharmacokinetics and dosimetry to normal organs. As a result of encouraging data in all of these areas, Pain Therapeutics plans to initiate a second study in which patients will receive increasing amounts of radioactivity delivered by the radiolabeled antibody. The radioactive doses delivered to these patients will be significantly higher than those delivered to the patients of the first study.

At the Society for Nuclear Medicine Annual Meeting in New Orleans, last week, research teams from each of the collaborating laboratories - at Albert Einstein College of Medicine (New York) and Hadassah Medical Center (Jerusalem) presented data related to Pain Therapeutics' melanoma program. This meeting is considered to be the world's most significant technical meeting focused on breakthrough developments in clinical imaging and nuclear medicine.

At the meeting, Dr. Dadachova also was presented with an award by the Society's Young Professionals' Committee. The award is given in recognition of significant contributions to the fields of nuclear medicine and molecular imaging by young researchers.

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