Cell Genesys' prostate cancer vaccine heads for the dustbin

News

Cell Genesys added to the growing list of therapeutic prostate cancer vaccine failures today with the announcement that the second phase III trial of its GVAX immunotherapy has been halted.

The decision was made after a futility analysis concluded the trial, called Vital-1, had less than a 30% chance of establishing an improvement in survival. With both pivotal trials now terminated, the company and its partner Takeda will review the programme, but the prognosis is poor. Cell Genesys is culling three-quarters of its staff and considering its options, including selling up and liquidating; shares in the company plunged 73% to a new low of 16 cents on the news.

Confidence in the project was already low; Vital-2 was stopped at the end of August after an imbalance of deaths was found between the two arms, which pitted GVAX in combination with Taxotere, against Taxotere and prednisone. That event caused shares in the company to plunge 72% on the day, investors no doubt mindful of the abject failure across the board of late-stage cancer vaccine projects recently.

The sorry list includes Favrille’s SpecifId in May and Genitope’s MyVax in December, disappointing results from Oxford BioMedica’s TroVax in July and less than convincing data from Dendreon’s Provenge earlier this month.

Tough target

While many experts believe that immunotherapies will have a role in fighting cancer in the future, the list above indicates that the science still has a long way to go. On a conference call this morning Stephen Sherwin, chief executive of Cell Genesys, speculated that metastatic prostate cancer is too tough a target for slow-acting therapies such as GVAX, or that the bar was raised too high by pitting it against a highly active chemotherapy agent like Taxotore.

Dr Sherwin, who could barely contain his disappointment at the results, said he remained convinced of the potential in the field, and the GVAX platform. With the company now effectively up for sale, whether anyone else shares his optimism should soon become apparent.

Asset sale

Although the company has a healthy cash pile, which is forecast to total $128m by the end of the year, it has a convertible note outstanding worth $145m, due in November 2011. This might deter a private company from reversing into the company to get a stock market listing and its hands on the cash, unless it is confident of generating revenues very soon.

The group has a handful of gene therapy projects in very early stage, and the cash could be spent rebuilding the pipeline. However, an asset sale where possible and winding up of the company looks more likely.

The GVAX platform might attract some interest. Two phase II trials are ongoing with GVAX immunotherapy products for leukaemia and pancreatic cancer, being conduced at John Hopkins University, results from which have been encouraging.

Preliminary results from Vital-2, the trial that was halted in August, were released today, concluding that no safety issues could have accounted for the imbalance of deaths, the vast majority of which were due to progressive prostate cancer.

More deaths were expected in Vital-2, as the patients had very advanced disease. However, the lack of efficacy in Vital-1, in patients less advanced and after encouraging results in the same population in phase II, is more disappointing. It seems very unlikely that Takeda will continue with the collaboration.

Late stage hopes

For the field of prostate cancer vaccines, the chance of notching up a success in the near future lies in the hands of full results from Dendreon's phase III Provenge trial, due in the middle of next year.

Reports have claimed that Dendreon's shares are heavily shorted, meaning that investors are betting the stock is going to fall in the future. The Cell Genesys' news will have made those gamblers more confident.

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