>>SAN DIEGO, Dec. 13 /PRNewswire-FirstCall/ -- Cell Genesys, Inc. (Nasdaq: CEGE - News) today announced data from a Phase I/II clinical trial of CG7870 oncolytic virus therapy in patients with localized recurrent prostate cancer that demonstrated antitumor activity as measured by reductions in serum levels of prostate-specific antigen (PSA) in 75 percent (9/12) of patients with elevated PSA levels at baseline. In the nine responders, prostate-specific antigen (PSA) levels decreased by 25-50 percent, and all patients remained progression-free at a median follow-up time of six months. Treatment with CG7870 was well tolerated and did not result in any serious treatment-related side effects. These data were presented at the International Conference on Gene Therapy of Cancer in San Diego, CA.
The Phase I/II trial of CG7870 enrolled 20 patients who had recurrent prostate cancer following radiation therapy but had not yet received hormone treatment. CG7870 was administered directly into the prostate using the same standard administration techniques used to implant radiation seed therapy for prostate cancer. Ten patients were treated at the lowest dose level, five at the middle dose level and five at the highest dose level, all with a single administration of the oncolytic virus therapy. Twelve patients were deemed evaluable due to elevated PSA levels at baseline. Based on the abovementioned clinical results, Cell Genesys expects to initiate a follow-on Phase II trial of intra-prostatic CG7870 in combination with external beam radiation in early-stage, high-risk prostate cancer patients in early 2003.
"We are encouraged by the data presented and have made a decision to advance CG7870 to the next stage of clinical development instead of our other prostate cancer-specific oncolytic virus therapy, CG7060," stated Joseph J. Vallner, Ph.D., president and chief operating officer of Cell Genesys. "Given that CG7870 is highly selective in killing prostate cancer cells and appears to be well tolerated in patients who receive it, we believe that CG7870 may have the potential to be a useful adjuvant to existing therapies for prostate cancer."
In preclinical studies, CG7870, the company's lead oncolytic virus therapy, has demonstrated a high therapeutic index of approximately 10,000:1, meaning that it only killed one normal cell for every 10,000 prostate cancer cells that it killed. This could translate into a much safer side effect profile than traditional therapies such as chemotherapy, which typically kills approximately six cancer cells for every normal cell that it kills (therapeutic index approximately 6:1). Additionally, previously reported clinical data for intravenously-administered CG7870 demonstrated that this route of administration was also well tolerated and that the prostate-specific oncolytic virus could produce stabilization of PSA levels in some patients after just one injection.
In related news, the company announced that CG8840 for bladder cancer has been selected as the next oncolytic virus therapy product candidate to enter clinical trials, and the company expects to file an investigational new drug (IND) application to initiate a Phase I/II study for this product by late 2003. At the American Association for Cancer Research (AACR) Annual Meeting in April 2002, Cell Genesys reported that significant antitumor activity was demonstrated when evaluating CG8840 alone and in combination with docetaxel in preclinical studies of bladder cancer. It is expected that CG8840 will be developed as a treatment for patients whose bladder cancers recur following surgery and other currently available local treatments. In addition to CG8840, Cell Genesys is also currently conducting preclinical studies of CG8900 for liver cancer and CG7980 for colon cancer.
Oncolytic (cancer cell killing) virus therapies are comprised of viruses that are engineered to preferentially replicate in and destroy cancer cells and represent a new approach to cancer therapy. The engineered viruses are delivered either by direct injection into tumors or by injection into a body cavity containing cancer, such as the bladder, and are thousands of times more specific for killing cancer cells than standard chemotherapeutic drugs. Once the therapy is delivered to the cancer cells, the virus replicates within the cancer cell until it bursts, thereby destroying the cell and spreading the newly created viruses throughout the tumor, repeating the cycle in the neighboring cancer cells. The virus is cleared by the body's immune system after destroying the cancer cells.<<
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