Vaccine Generates Powerful Immune Responses In Preclinical Studies.(prostate cancer vaccine)

2001 OCT 10 - (NewsRx.com & NewsRx.net) --

The PSMA Development Company LLC, a joint venture of Progenics Pharmaceuticals, Inc. and Cytogen Corporation, has entered into a worldwide exclusive licensing agreement with AlphaVax Human Vaccines, Inc., to use the AlphaVax Replicon Vector (ArV) system to create a therapeutic prostate cancer vaccine incorporating the joint venture's proprietary antigen prostate specific membrane antigen (PSMA).

The announcement follows an extensive preclinical evaluation of the ArV technology as a vaccine delivery and expression vehicle for PSMA, a well-recognized marker that is abundantly expressed on prostate cancer cells. Mice inoculated with the vaccine developed robust and specific immune responses to PSMA that persisted for prolonged periods. The scientific findings were presented at the Eighth Annual CaP CURE Scientific Retreat in Lake Tahoe, Nevada.

"This collaboration with AlphaVax represents a new application of this powerful technology for prostate cancer therapy," said William C. Olson, PhD, Progenics, and lead author of the presentation. "The potent and durable immune responses observed to date are encouraging indications of the potential for this vaccine to eliminate prostate cancer cells in man. We are completing our preclinical development activities on the PSMA ArV vaccine in anticipation of Phase I/II clinical studies in 2002."

The PSMA-based therapeutic vaccine, which employs the body's own defense mechanisms to identify and destroy prostate cancer cells, yielded both antibodies and killer T cells, the two principal mechanisms used by the immune system to eliminate harmful cells. A subcutaneous injection of a genetically engineered, non-replicating viral vector containing the human DNA sequence that encodes a form of PSMA protein, generated high levels of PSMA-specific cytotoxic CD8(+) killer T cells, helper CD4(+) T cells and antibodies in mice. The broad cellular (killer T cell) and humoral (antibody) responses were long lasting, and are essential mechanisms for targeting and eliminating prostate cancer cells, which typically express PSMA on their surfaces.

"Antigen-presenting cells are an important target for therapeutic cancer vaccines, because they alert the body to the presence of infectious agents and to cancers," said Howard I. Scher, MD, chief, Genitourinary Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, New York. "PSMA is a human protein that escapes the immune system. Vaccine Replicon Particles help to break this tolerance, to retrain the immune system to recognize PSMA as a danger signal, and to eliminate PSMA-expressing cancer cells."

The core of the ArV system is an engineered, weakened form of Venezuelan Equine ...