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Cell Genesys Reports Encouraging Follow Up Clinical Data From Phase 2 Trial of GVAX(R) Leukemia Vaccine

Posted on: Tuesday, 7 December 2004, 09:00 CST

SAN DIEGO, Dec. 7 /PRNewswire-FirstCall/ -- Cell Genesys, Inc. today reported follow up clinical data from an ongoing Phase 2 trial of GVAX(R) cancer vaccine for acute myelogenous leukemia (AML). Patients with newly diagnosed leukemia were treated with chemotherapy, and if responsive, subsequently received autologous bone marrow stem cell transplantation and GVAX(R) leukemia vaccine. The ongoing findings of this trial indicate that vaccine therapy is well tolerated and may reduce residual leukemic cells that persist after chemotherapy as indicated by decreased levels of WT-1, a leukemia-associated genetic marker, which is detectable in over 95 percent of patients with active AML. The interim trial results were reported in an oral presentation at the American Society of Hematology (ASH) Annual Meeting in San Diego, CA, by Dr. Dan DeAngelo from the Dana Farber Cancer Institute at Harvard University (ASH Abstract #441).

The Phase 2 trial was conducted at four leukemia bone marrow transplant centers in the United States and enrolled 54 patients. To date, 28 patients have initiated GVAX(R) vaccination after achieving a complete response to chemotherapy and thus far 19 of these patients have completed the stem cell transplantation and initiated a series of post-transplant vaccinations. The majority of patients had detectable WT-1 levels in their blood following chemotherapy indicating persistent leukemic cells. There were post-vaccination declines in WT-1 in 11 of 16 patients (69 percent) in the blood and in 12 of 20 (60 percent) in the bone marrow. The median decrease in WT-1 in the blood following just a single outpatient vaccination was approximately 90% and was greater in magnitude than that seen following high dose consolidation chemotherapy which requires a multiple-week hospital stay. In addition, with a median follow up of 12.5 months, relapse-free survival was 67% for the 28 patients who achieved complete remission following chemotherapy and GVAX(R) vaccination. Furthermore, relapse-free survival was greater in the 11 patients who showed a decrease in WT-1 in the blood following the single pre-transplant vaccination compared to those who did not (80% vs. 0%, p=0.02). Relapse-free survival was also greater in the 18 patients who achieved an undetectable level of WT-1 in the blood following post-transplant vaccinations (90% vs. 20%, p=0.002), consistent with the potential clinical relevance of WT-1 as a marker of persistent leukemia. To date, there have been no serious side effects considered related to the experimental GVAX(R) leukemia vaccine therapy.

"We are encouraged by the results of our ongoing Phase 2 study of GVAX(R) vaccine in acute leukemia, particularly the newly reported findings regarding relapse-free survival," stated Joseph J. Vallner, Ph.D., president and chief operating officer of Cell Genesys. "We believe that GVAX leukemia vaccine represents a potential new treatment option for acute leukemia that may improve on the results of chemotherapy, a particularly important development strategy to consider for elderly patients and patients for whom bone marrow transplantation is not readily available or indicated."

In related news, Cell Genesys reported that updated data from the Phase 1/2 trial of GVAX(R) myeloma vaccine were also presented at the ASH Meeting (ASH Abstract #440). Patients with advanced multiple myeloma were treated with chemotherapy, and if responsive, subsequently received autologous bone marrow stem cell transplantation and GVAX(R) vaccination. The trial enrolled 22 patients, and 18 patients received at least one GVAX(R) vaccination. Combination therapy with transplantation and GVAX(R) vaccine resulted in six complete responses, five partial responses, three patients with stable disease and two patients with progression. Importantly, three of the responders progressed after transplantation and then demonstrated antitumor activity attributed to vaccination as measured by reductions in the myeloma-associated circulating protein (M-spike) of 92 percent, 37 percent and 25 percent. Treatment with GVAX(R) myeloma vaccine to date has been safe and well tolerated.

The form of GVAX(R) vaccine used in both the leukemia and myeloma clinical trials is a non patient-specific GVAX(R) product manufactured at Cell Genesys that is mixed at the treatment center with the patient's irradiated tumor cells that were collected prior to chemotherapy. Cell Genesys believes that this product could potentially be developed as an off-the-shelf pharmaceutical for use in multiple types of hematologic malignancies. Future manufacturing of the product would be expected to occur at the company's plant in Hayward, California, one of three Cell Genesys manufacturing facilities with Phase 3 and potential market launch production capabilities.

Clinical trials of GVAX(R) cancer vaccines are under way for multiple types of cancer including prostate cancer, lung cancer, pancreatic cancer, leukemia and myeloma. Cell Genesys' GVAX(R) cancer vaccines are whole-cell vaccines, which are designed to stimulate an immune response against the patient's tumor. The vaccines are comprised of tumor cells that have been irradiated and genetically modified to secrete GM-CSF (granulocyte-macrophage colony stimulating factor), an immune stimulatory hormone which plays a key role in stimulating the body's immune response to vaccines.

Cell Genesys is focused on the development and commercialization of novel biological therapies for patients with cancer. The company is pursuing three cancer product platforms -- GVAX(R) cancer vaccines, oncolytic virus therapies and antiangiogenesis therapies. Clinical trials of GVAX(R) cancer vaccines include an ongoing Phase 3 trial of GVAX(R) prostate cancer vaccine as well as trials of GVAX(R) vaccines for lung cancer, pancreatic cancer, leukemia and myeloma. Clinical programs of oncolytic virus therapies include CG7870 for prostate cancer. Preclinical studies are in progress for additional GVAX(R) cancer vaccines, oncolytic virus therapies and antiangiogenesis therapies for multiple types of cancer. Cell Genesys' subsidiary, Ceregene, Inc., is focused on gene therapies for neurologic disorders. Cell Genesys also continues to hold an equity interest in its former subsidiary, Abgenix, Inc., an antibody products company. Cell Genesys is headquartered in South San Francisco, CA and has manufacturing operations in San Diego, CA, Hayward, CA and Memphis, TN. For additional information, please visit the company's website at http://www.cellgenesys.com/.

Statements made herein about the company and its subsidiaries, other than statements of historical fact, including statements about the company's progress, results and timing of clinical trials and preclinical programs and the nature of product pipelines are forward-looking statements and are subject to a number of uncertainties that could cause actual results to differ materially from the statements made, including risks associated with the success of clinical trials and research and development programs, the regulatory approval process for clinical trials, competitive technologies and products, patents, continuation of corporate partnerships and the need for additional financings. For information about these and other risks which may affect Cell Genesys, please see the company's Annual Report on Form 10-K for the year ended December 31, 2003 dated March 4, 2004 as well as Cell Genesys' reports on Form 10-Q and 8-K and other reports filed from time to time with the Securities and Exchange Commission. The company assumes no obligation to update the forward-looking information in this press release.

Contact: Ina Cu

Investor Relations

Cell Genesys, Inc.

650-266-3200

Cell Genesys, Inc.

CONTACT: Ina Cu, Investor Relations of Cell Genesys, Inc.,+1-650-266-3200

Web site: http://www.cellgenesys.com/

Source: PRNewswire-FirstCall

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