Agenus stock jumps on Phase II brain cancer vaccine data

Agenus ($AGEN) has fallen a long way since its stock briefly traded for $300 a share in 2000. The failure of its partner GlaxoSmithKline's ($GSK) cancer vaccine in September sent the stock tumbling 23% to $2.84 and it continued to drop in the following months. Now though, Agenus has good news to report.

Positive data from the company's single-arm Phase II trial of a brain cancer vaccine sent its stock up more than 30%, Monday. The study gave the personalized cancer vaccine Prophage Series G-200 to 41 patients with recurring glioblastoma multiforme. After 6 months of treatment, 90% of the patients were still alive. Agenus compared the result to historical data showing patients with recurring glioblastoma multiforme have an overall median survival of three to 9 months. The figure for the trial patients was 11 months.

A few aspects of the study and resulting data raise doubts about the vaccine though. While 90% of patients were alive after 6 months, only 30% survived a year. The use of a single-arm study model, in which there is no control group, is another potential criticism of the trial. Regulators have traditionally favored the use of a control group that takes part in the trial but doesn't receive the experimental treatment. Data from this group is then compared with the treatment arm to establish the effect of the therapeutic.

Despite these potential weaknesses--and the fact Agenus first reported the 90% 6-month survival figure at a meeting back in April 2012--investors reacted favorably to the news. Agenus shares jumped 36% in morning trading, but slipped in the afternoon to close up 13%. A larger, National Cancer Institute-funded trial is underway. The study is enrolling 220 patients with recurrent glioblastoma multiforme to test if the vaccine, which is derived from each person's tumor, can program the immune system to target the cancer.

- here's the press release
- read Reuters' article
- check out FierceBiotech's report