Early stage pancreatic cancer expresses antigen targeted by Immunomedics' PAM4 antibody

Immunomedics has reported in an oral presentation at the 2007 Annual Meeting of the American Association for Cancer Research (AACR) that the antigen targeted by the humanized PAM4 antibody is expressed in early stage pancreatic cancer specimens, a stage before the tumor becomes invasive.

Using immunohistochemical labeling of patient tumor specimens, Dr. David. V. Gold of the Garden State Cancer Center, Belleville, NJ, in collaboration with Dr. Ralph. H. Hruban of Johns Hopkins Medical Institutions, Baltimore, MD, found that over 89% of 56 specimens of early pancreatic cancer tested positive with the PAM4 antibody. Likewise, 87% of 48 specimens of invasive adenocarcinoma of the pancreas showed positive labeling with PAM4.

According to Dr. Gold, "We found the expression of this biomarker identified by the PAM4 antibody in the earliest phase of pancreatic cancer, specifically, in 89% of 24 specimens. Importantly, the antibody did not react with normal pancreatic tissue. We believe this indicates to us that the PAM4 antibody recognizes an early biomarker for this disease, which is commonly diagnosed too late for effective therapy."

Dr. Gold is collaborating with Immunomedics to develop an early blood test to detect pancreatic cancer. Immunomedics is completing a dose-finding study evaluating the safety and tolerability, as well as initial anticancer activity, of its humanized PAM4 antibody labeled with the therapeutic isotope, yttrium-90. At the AACR conference, Dr. Gold reported on a case where the PAM4 antibody was able to localize a recurrence of pancreatic cancer in a patient who had earlier tumor resected.

Cynthia L. Sullivan, President and Chief Executive Officer of Immunomedics, remarked: "PAM4's improved sensitivity for early pancreas cancer, matched with its known high specificity for this disease based on prior work by this group, is supportive of our decision to bring it rapidly into clinical trials. Initial results from our phase I/II studies of hPAM4 in patients with pancreatic cancer will be released at the annual meeting of the Society of Nuclear Medicine in June."

About PAM4

PAM4 is an antibody that recognizes a specific biomarker (MUC1) made almost exclusively by pancreatic cancer. Developed by Dr. David V. Gold, the antibody was reported to detect an elevation of this biomarker in the blood of over 80% of patients diagnosed with pancreatic cancer. Animal studies with transplanted human pancreatic cancer demonstrated that PAM4, radiolabeled with yttrium-90, had a very strong effect in reducing tumor growth, even curing some animals. Although the radiolabeled PAM4 antibody was superior to gemcitabine alone, the combination of radiolabeled PAM4 antibody and gemcitabine was more active in controlling pancreatic cancer growth than either agent by itself, thus suggesting synergistic effects.

About Pancreatic Cancer

According to the National Cancer Institute, pancreatic cancer is the fourth leading cause of cancer death in the United States. In 2007, about 37,000 Americans are expected to be diagnosed with the disease, and about 33,000 patients will die from it. For patients with advanced cancers, the overall 5-year survival rate of all stages is less than 1%. For those patients with small and localized disease that can be completely resected surgically, 5-year survival rates improve to 18% to 24%. Although early detection and diagnosis is key for survival, it is rare to detect this lethal cancer early due to the retroperitoneal location of the pancreas, a relatively inaccessible location in the abdomen. The tumor is allowed to grow in a silent fashion with only vague symptoms that makes it difficult to distinguish from an inflammation of the pancreas, or pancreatitis. Currently, the standard therapy for pancreatic cancer is gemcitabine, alone or in combination with other chemotherapeutics.