By Lisa Seachrist

Washington Editor

The Immune Response Corp.’s rheumatoid arthritis (RA) therapy, IR501, showed statistically significant improvement of RA symptoms when compared to placebo in a Phase II clinical trial, the company said Tuesday, adding that it plans to put the therapy into Phase III clinical trials this year.

A Phase II trial of a similar compound, IR502, targeted against psoriasis, however, failed to show a difference between treated and control groups. However, the company has plans to reformulate it and have it in Phase II clinical trial in the first part of 1997.

“These findings are very exciting,“ said Charles Cashion, vice president, finance, for the Carlsbad, Calif., company. “And, they should be the basis of a corporate collaboration.“

Cashion told BioWorld Today that several companies have expressed interest in IR501 but were waiting for the results of this study before starting any negotiations.

The products that Immune Response tested are essentially therapeutic vaccines. Each product includes peptides against the type of T cell that has begun to attack the body. In RA, a certain type of CD4 cell appears to cause the inflammation in the synovial fluid whereas it is a type of CD8 cell that is the culprit in psoriasis. By injecting peptides found on these types of T cells with an adjuvant, the company hopes to help the body down-regulate these cells and control the disease.

“Essentially we are going after the cause of the disease rather than merely attacking the symptoms,“ Morgan said.

In the RA trial, the company tested 90 microgram doses and 300 microgram doses against adjuvant alone. Patients received a single injectionduring the first, fourth, eighth and 20th weeks. Patients in both of the treatment groups showed improvement in their disease. However, the 90 microgram dose appeared to be more effective. After the third injection, 56 percent of patients who received the 90 microgram doses had significant improvement in their disease as rated by the American College of Rheumatology ACR 20 criteria. After the fourth injection 50 percent of the patients met the ACR 20 criteria. The 300 microgram dose resulted in 25 percent and 37 percent respectively while the placebo group only saw a 19 percent improvement.

“What is so encouraging about this trial is that it was designed to show trends, not significance and we see statistically significant results,“ said Cashion.

The very nature of psoriasis may have been working against the company in its attempt to test IR502. Psoriasis waxes and wanes throughout the year. Typically, the disease flares in the winter and resolves in the summer. The trial began in January and ended in August when symptoms are less severe. Nevertheless, Steven Richieri, senior vice president of operations, noted that they found a more immunogenic peptide that the company intends to include in a new formulation and test in a Phase II trial.

“This is good news for the company,“ said Robert Swift, vice president of Equity Research in Healthcare at Hanifen Imhoff Inc., in Denver. “It sets them up for a likely corporate collaboration.“

Swift told BioWorld Today the fact that the company saw a statistically significant result in a Phase II clinical trial, which was not powered for significance, proves “the underlying technology has viability. “This is a very robust result that should make it easy for the company to roll into a Phase III trial,“ he said. “It should also broaden the investors’ view of the company.“

Immune Response’s stock (NASDAQ:IMNR) was up $0.50 to close at $8.875 on the news.