Investigational Compound Shows Antitumor Activity.(Brief Article)

2001 DEC 5 - (NewsRx.com & NewsRx.net) -- Millennium Pharmaceuticals, Inc., and the New York Weill Cornell Medical Center reported interim findings of two ongoing Phase I clinical trials of an investigational drug, radiolabeled J591, in patients with advanced prostate cancer.

J591 is a humanized monoclonal antibody-based therapeutic. In these trials, the antibody delivered radiation directly to prostate cancers and demonstrated antitumor activity with tolerable and limited side effects. The findings were presented October 19, 2001, at the Venetian Institute of Molecular Medicine's New Trends in Prostate Cancer meeting in Padova, Italy.

J591 targets a molecule called prostate specific membrane antigen or PSMA. PSMA is a protein that is located on the cell surface of all prostate cancers. In these trials, J591 carries a radiation-emitting isotope attached to it. The goal of this therapy is to use J591 to target the radiation just to the tumor cells, while minimizing radiation to normal cells.

"Prostate cancer is the third most common cause of cancer deaths in men. Once cancer cells escape the prostate, the current standard of care is hormonal treatment. While it is not clear that hormonal therapy provides any survival benefit, it is clear that it causes significant side effects. Early investigation into J591 suggests that it is a promising new therapy that could fill a substantial unmet medical need," said lead study investigator Neil H. Bander, MD, the Bernard and Josephine Chaus professor of Urologic Oncology at New York Presbyterian Hospital/Weill Cornell Medical Center. "And because J591 targets only prostate cancer cells, there is the potential to offer patients fewer side effects."

The two studies which were reported each measure the effects of two distinct radioisotopes attached to J591, 177Lu (Lutetium) and 90Y (Yttrium). The studies included 26 patients whose prostate cancer had spread throughout the body and whose disease was progressing despite both hormonal treatment and, in most of the cases, chemotherapy. In these phase I studies, the dose of isotope is progressively increased in groups of patients in order to determine the maximal tolerated dose. Thus far, therapy with the radiolabeled antibodies has been well tolerated as patients have developed no symptoms as a result of the treatment.

Blood tests revealed an anticipated drop in platelet counts that spontaneously returned to normal. The low frequency of side ...