were hammered Friday after the biotech firm said its experimental HIV/AIDS vaccine had suffered a major setback.
Investor reaction to the bad news sent shares in the Carlsbad, Calif., company down $3.01, or 61.4%, to $1.89 in Friday trading.
Immune Response said that a midstage test of its vaccine, Remune, failed to slow the growth of the HIV virus in patients' blood. The study was conducted in Spain on 243 patients. The company was hoping to prove that Remune could stimulate the body's immune system to fight HIV infection.
Remune's setback comes as two rival companies working on HIV/AIDS vaccines try to make steady progress. Earlier this week,
said its experimental drug, Aidsvax, produced a broader immune response than previously expected. VaxGen will take the wraps off interim results from late-stage tests for Aidsvax in November.
announced positive results from its effort, although the experimental vaccines are still being tested in the laboratory and have not yet been tried on patients.
Immune Response's technology is based on the work of Dr. Jonas Salk, the famous immunologist and inventor of the polio vaccine. Remune is made from modified, killed HIV that is designed to stimulate the body's infection-fighting T cells to develop immunity to HIV.
Friday, the company did say that the Spain study noted a subgroup of patients with stronger immune systems that seemed to respond well to Remune.
"The result of this trial may have identified the patient population that is potentially immunologically capable of responding to an immune-based therapy in which therapeutic vaccination with Remune may exert a positive impact on viral load," said Eduardo Fernandez-Cruz, the principal investigator and doctor in charge of the Remune test, in a statement.
But that glimmer of hope may not be enough.
"This is a big setback for Immune Response and its main partner,
," says John McCamant, editor of the
Medical Technology Stock Letter
. "But in many ways, it shouldn't come as a surprise because developing a vaccine for HIV/AIDS is a very difficult task." McCamant has no position in Immune Response.