Trials of Immune Response Corp’s AIDS vaccine Remune may end after Pfizer drops financial support

Pfizer Inc. notified Immune Response Corp. on Friday that it was pulling out of their collaboration on the AIDS vaccine candidate Remune sending Immune Response’s stock “plung[ing]” and leaving the future of the vaccine candidate in doubt, the New York Times reports.

The company’s withdrawal, which Immune Response Vice President for Medical and Scientific Affairs Dr. Ronald Moss said “came out of the blue,” could put an end to a clinical trial of the vaccine being conducted by Pfizer, a trial the Times said represented the “best hope of proving that the drug works.” The pullout also leaves Immune Response with only $12 million in cash to further fund vaccine trials. Pfizer, which inherited the partnership when it acquired Agouron Pharmaceuticals, had already paid Immune Response $47 million and could have supplied an additional $30 million. Pfizer said it decided to terminate the partnership because Immune Response, founded by the late Dr. Jonas Salk, inventor of the polio vaccine, had not produced “convincing evidence” that Remune “helps patients” (Pollack, New York Times, 9/7). “Our decision was based on review of the data from several clinical trials. Our decision to withdraw … should not be interpreted to mean that immune-based therapies as a class does not merit further investigation,” Pfizer spokesperson Kim Simon said.

Trial results varied

Remune utilizes an approach “similar” to Salk’s polio vaccine, using “inactivated” HIV to “bolst[er]” the patient’s T-cell production (Dow Jones/Wall Street Journal, 9/7). The vaccine is not intended to prevent infection but is designed to help patients “keep the virus in check,” the Times reports.

Some studies have shown Remune to “provoke” an immune response; however, they have not shown that the vaccine actually helps patients, and “many” scientists do not think using an inactivated virus offers the “best” hope for a successful vaccine. A trial involving more than 2,500 patients “failed to show that Remune improved survival or lengthened the time before HIV infection progressed to AIDS.” Immune Response officials said that the trial coincided with increased use of new AIDS drugs, making it “nearly impossible” to “show a benefit over the placebo.”

Last year, scientists accused Immune Response of attempting to “squelch” the publication of a scientific paper that described a failed clinical trial, and in 1995, the FDA “warned” the company “not to manipulate data” to show better results. Moss said that he was “puzzled” by Pfizer’s reasoning to withdraw funding because new data, set to be presented Wednesday at an AIDS conference in Argentina, will show that the vaccine was effective in a “subset of patients with stronger immune systems.”

Dr. Eric Rosenberg of Harvard Medical School said that the loss of funding could mean a “potentially good vaccine may not be adequately tested, and it deserves to be.” Pfizer is “very foolish” to terminate the partnership, Dr. Fred Valentine, a professor of medicine at New York University, added. John McCamant, editor of Medical Technology Stock Letter, said he did not know where Immune Response could “go from here,” citing the 44% drop the company’s stock took Friday after the announcement. Pfizer’s “no-confidence vote” could cause other potential investors to “balk,” the Times reports (New York Times, 9/7).