Cell Genesys anticipates completing a Phase III study of its experimental GVAX immunotherapy in the second half of 2009 after an interim analysis gave the study data a green light, CEO Stephen Sherwin said during a Jan. 14 conference call.

The trial, VITAL-1, is a multi-centered, randomized, controlled study comparing Cell Genesys' GVAX immunotherapy as a monotherapy against Sanofi-Aventis' Taxotere (docetaxel) plus prednisone in patients with asymptomatic metastatic hormone refractory prostate cancer. The primary endpoint of the study is improvement in survival.

The South San Francisco, Calif., firm announced in 2004 that it would launch the study under an FDA special protocol assessment (¹ Also see "Cell Genesys GVAX Prostate Cancer Vaccine Will Begin Phase III Under Special Protocol Assessment" - Pink Sheet, 10 May, 2004.). Enrollment of 626 patients was completed in July 2007.

A second study in Cell Genesys' prostate cancer program, VITAL-2, compares GVAX immunotherapy plus Taxotere to Taxotere and prednisone in symptomatic metastatic HRPC patients. The primary endpoint of that study is also improvement in survival.

VITAL-2 was initiated in 2005, and the firm is targeting the first half of 2009 to complete enrollment of approximately 600 patients. An event-triggered interim analysis is anticipated at that time.

Cell Genesys is in ongoing partnering discussions for the immunotherapy. If a deal is going to be completed before the firm has Phase III data in hand, it will have to be signed in 2008, given the company's development timeline for the program, the exec said.

The firm's priority in seeking a partner is strategic assistance to ensure a successful launch of the immunotherapeutic, rather than issues such as geographies, Sherwin said.

"We are looking for a partner ... that understands that with all of the risk and investment of dollars that we've made here, that we have the ability to share substantially in the downstream benefit of a successful product."

According to Cell Genesys, GVAX cancer immunotherapies are non-patient-specific therapeutics comprised of whole tumor cells modified to secrete granulocyte-macrophage colony stimulating factor. The cells are then irradiated for safety.

Cell Genesys also is studying GVAX immunotherapies in Phase II trials in pancreatic cancer and leukemia.

Other companies working on a therapeutic cancer vaccine include New York-based Antigenics, which announced in October that its patient-specific vaccine Oncophage (vitespen) was entering Phase II for recurrent glioma (² Also see "Antigenics’ Oncophage Cancer Vaccine Enters Phase II Glioma Study" - Pink Sheet, 10 October, 2007.).

Seattle-based Dendreon is awaiting interim results from an ongoing Phase III prostate cancer study of its therapeutic vaccine candidate Provenge (sipuleucel-T) in mid-to-late 2008. The company will add that data to its BLA, which received a "complete response" letter from FDA in May (³ Also see "Provenge Review In 2008 Hinges On IMPACT Interim Analysis" - Pink Sheet, 31 May, 2007.).

-Shirley Haley (s.haley@elsevier.com)

Cell Genesys Set To License Phase III Cancer Immunotherapeutic; Final Data Likely In 2009

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