Biotech Values

[DewDiligence]

Update on the PSMA front (FWIW):

[Note that this is not the same therapeutic agent as the PSMA mAb from CTYO coupled to the radioactive payload from Dow (#msg-6291949).]

http://biz.yahoo.com/bw/050930/305154.html?.v=1

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Progenics and Cytogen Report Potent Anti-Tumor Activity for Experimental Prostate Cancer Drug

SCOTTSDALE, Ariz.--(BUSINESS WIRE)--Sept. 30, 2005--PSMA Development Company LLC (PDC), a joint venture of Progenics Pharmaceuticals, Inc. (Nasdaq: PGNX - News) and Cytogen Corporation (Nasdaq: CYTO - News), today announced positive preclinical findings of its novel prostate cancer drug, prostate-specific membrane antigen (PSMA) antibody-drug conjugate (ADC). The findings were reported today by Dangshe Ma, Ph.D., Progenics' Senior Investigator, at the 12th Annual Prostate Cancer Foundation Scientific Retreat.

In a mouse model of human prostate cancer, PSMA ADC significantly prolonged overall survival up to nine-fold as compared to untreated animals (p=0.0018, log-rank test, two-sided). Remarkably, established tumors in two of the five animals treated at the highest dose were eradicated and remained undetectable over 500 days through the completion of the study. No overt evidence of toxicity was observed in any of these animal model tests.

ADC drugs link a monoclonal antibody which targets specific cells in the body, such as cancer cells, with a cell-killing payload. PSMA ADC is a human monoclonal antibody targeting PSMA, which is abundantly expressed on the surface of prostate cancer cells, coupled to auristatin, a highly potent drug. As a result, PSMA ADC is targeted to prostate cancer cells and incorporated into them, releasing the drug payload inside the cancer cell. The technology to link the PSMA monoclonal antibody to auristatin is being developed by PDC in collaboration with Seattle Genetics, Inc. (Nasdaq: SGEN - News).

"Prostate-specific membrane antigen represents an excellent target in cancer therapy for many reasons. It is an integral membrane protein that is abundantly and preferentially expressed on the surface of prostate cancer cells," said Warren D.W. Heston, Ph.D., Director, Research Program in Prostate Cancer, The Cleveland Clinic Foundation. "PSMA expression is high in prostate cancers that no longer respond to hormonal therapies and for which there are few treatment options. In addition, PSMA is abundantly expressed on endothelial cells of new blood vessels that supply most other solid tumors. Once the PSMA monoclonal antibody has bound to the cancer cell, PSMA ADC is rapidly internalized, making it especially well suited for the 'armed antibody approach' of this compound. Today's findings represent a positive step toward developing PSMA ADC as a novel therapy for metastatic prostate cancer."

"PSMA ADC combines the tumor-targeting properties of our PSMA monoclonal antibody with the cell-killing properties of auristatin, a highly potent drug that disrupts the internal scaffolding that cancer cells require to grow and divide," said William C. Olson, Ph.D., Vice President of Research & Development at Progenics and senior author of the presentation. He added, "PSMA ADC can be considered a targeted form of chemotherapy where it attacks prostate cancer cells, but spares healthy tissues. PSMA ADC eradicated established tumors in some of the mice without any observed toxicity. The findings support further development of PSMA ADC for therapy of prostate and other cancers."

PSMA ADC was also tested in vitro and in animals for the ability to selectively eliminate prostate cancer cells. In laboratory studies, PSMA ADC killed PSMA-expressing prostate cancer cells at picomolar concentrations, whereas approximately 1000-fold higher concentrations were required to kill cells that lack PSMA. PSMA ADC was similarly active against prostate cancer cells that were either sensitive to or resistant to androgen deprivation. In addition to improving survival, PSMA ADC resulted in significant, 700-fold reductions (p = 0.0086, t-test, two-sided) in serum levels of prostate-specific antigen (PSA) in animal tests. PSA is a well-recognized surrogate marker of prostate cancer progression and response to therapy.
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