The Immune Response Corp. on Friday gained all rights to an HIVimmunotherapeutic vaccine that was being developed with Rhone-Poulenc Rorer Inc. Immune Response plans to take the unnamedproduct into Phase III trials when given FDA approval.

In January an FDA advisory committee recommended that the FDAallow the Phase III trial, although the committee members' supportfor the product's efficacy was not overwhelming. Immune Response,of Carlsbad, Calif., still must get validation of its manufacturingfacility, FDA approval of the protocol and approvals from the sitesparticipating in what is planned to be a 5,000-patient study.

HIV-1 Immunogen, which is what the vaccine has been called, wasbeing developed by Immunization Products Ltd., a joint ventureformed between Immune Response and Rhone-Poulenc in 1988 todevelop the vaccine.

The companies have shared equally in nearly $60 million in costs todate of the venture, officials at both companies said.

Bob Pearson, Rhone-Poulenc's executive director, productcommunications, told BioWorld development of the vaccine is takinglonger than initially anticipated. Immune Response, which has hadfull responsibility for clinical and regulatory duties, is seekingapproval for a Phase III trial that could last a few years.

"The development plans have changed since 1988, when we firststarted working together," Pearson said. "We thought the compoundwould undergo accelerated development and perhaps acceleratedapproval based on our Phase II trials.

"Immune Response has shown a clear commitment to thedevelopment program, so we feel it's best that Immune Responsedoes the development," Pearson said. "We decided to withdraw fromthe project, but in a way that won't cause any delay in the clinicaldevelopment program."

Steve Basta, Immune Response's executive director of productdevelopment, told BioWorld that development of the HIV therapeutichas been the company's primary focus since its founding.

"We think it's a tremendous opportunity," Basta said of Rhone-Poulenc's relinquishment of rights. "We acquired rights to a Phase IIIproduct, one that clearly is a leader among immune-based therapiesfor HIV, and we're going to aggressively develop this product."

Basta said Immune Response, with about $55 million in cash andequivalents, has funding through 1996, giving the company enoughmoney to get "well along the way" in the Phase III study. A newpartner is a new priority, however.

"We're going to be initiating discussions with potential partnersquickly," he said, adding that the Phase III studies won't be delayedwhile a partner is sought.

Immune Response and Rhone-Poulenc had been in a disputeconcerning clinical and regulatory issues related to the product.Immune Response contended it had the lead in those areas, whileRhone-Poulenc said all rights should be assigned to the joint venture.Last May an arbitrator ruled in Immune Response's favor.

The product is designed to stimulate antibody and cell-mediatedresponse. It was cultured, purified then inactivated by a chemical-killing process and irradiation of the virus. The inactivated HIV thenwas stripped of its outer envelope, purified, then emulsified with anadjuvant.

Immune Response's proposed Phase III trial calls for three arms. Thelargest, involving about 3,000 patients with CD4 counts between 300and 549, is designed to monitor patients to the endpoint of an AIDS-defining clinical condition.

Another arm will include about 300 patients with CD4 counts greaterthan 550. Endpoints are viral load and CD4 count. The final armwould involve about 1,500 patients with CD4 counts below 300, whowill be monitored to determine if survival is extended.

Study participants will stay on whatever therapy they already are on,and each group will be divided into thirds. One-third of each groupwould be injected with an adjuvant as control, one will get 100micrograms of the HIV-1 Immunogen and the third will get 400micrograms of the vaccine. The intramuscular injection will be givenevery three months.

Immune Response's stock (NASDAQ:IMNR) lost about 18.5 percentFriday, closing down 81 cents at $3.56 per share. n

-- Jim Shrine

(c) 1997 American Health Consultants. All rights reserved.