Multiple Peptide Systems (MPS) of San Diego announcedTuesday that the malaria vaccine it is producing for the WalterReed Army Institute of Research has entered clinical trials.

MPS is producing the putative vaccine in its GoodManufacturing Practices (GMP) peptide production facility."MPS is making multiple-gram quantities of this peptide forWalter Reed, all under GMP-certified conditions," said GlenAmbra, MPS's vice president of marketing.

"The vaccine was developed by Dr. Manual Patarroyo severalyears ago at the Hospital of San Juan de Dios Institute ofImmunology in Bogota, Columbia," said Richard Houghten, afounder of MPS. He added that Walter Reed chose MPS to"attempt reproduction of Patarroyo's vaccine."

"Our preclinical data match Patarroyo's exactly," said RipleyBallou, chief of the department of immunology at Walter Reed.Walter Reed filed an investigational new drug (IND) applicationwith the FDA in August and started recruiting volunteers forPhase I trials on the potential vaccine last month. The trials arenow under way, Ambra said.

Although the U.S. clinical trials on this compound are justbeginning, Patarroyo and his colleagues have conducted theirown extensive clinical investigations and have vaccinated about30,000 people in South America and Africa, Houghton toldBioWorld.

From these trials, he added, it appears that vaccination iseffective for six months to one year.

Houghton said the vaccine is a combination of segments ofthree different surface proteins of the malarial parasite. Each ofthese segments, Houghton said, consists of about 15 aminoacids.

"We piece these three segments together to get a 45 amino acidpeptide, put a cysteine on the end, and polymerize it to form ahigh molecular weight polymer."

This peptide polymer, combined with the adjuvant alum, formsthe vaccine.

Immunization should raise antibodies against the malarialparasite's antigenic epitopes. The strategy is to "block theparasites quickly, to prevent them from ever getting into thered blood cells (where they start the infective cycle)," Houghtonsaid. "This approach makes a lot of sense. If you're going to getrid of malaria, you have to do it as a first line of defense," hesaid. The vaccine is intended for people who have never beenexposed to the disease.

Because the parasitic organism that causes malaria goesthrough four life-cycle phases in its human host, with eachstage exhibiting its own peculiar antigenic characteristics,developing a malarial vaccine has been a tough problem forresearchers.

Some researchers feel that it will be necessary to develop amultivalent vaccine that recognizes all stages so that it can beeffective at every stage of an individual patient's diseaseprogression. Also, the parasite mutates rapidly, becomingresistant to many drugs and frustrating attempts at creating auniversal vaccine.

Even when researchers have been able to come up with avaccine candidate that can raise an immune response and agood antibody titer, they still haven't been able to show that itprevents the transmission of the disease, pointed out FranklinBerger, an analyst with Josephthal, Lyon and Ross Inc. of NewYork.

Another company working on a malarial vaccine is Viagene Inc.of San Diego, which in August began a collaboration withWalter Reed for a vaccine using retroviral gene transfer toprevent the disease.

Chiron Corp. of Emeryville, Calif., had a malaria vaccineprogram and still owns the technology. But Phase I clinicalstudies on the recombinant vaccine showed that it didn't reallyelicit an immune response, said Larry Kurtz, Chiron's vicepresident of corporate communications. With so many otherpromising products in development, Kurtz said, Chiron "decidedto table it."

MPS is a wholly owned subsidiary of Houghton PharmaceuticalsInc., also of San Diego, which is funded by Domain Associatesand the Perkins group.

-- Jennifer Van Brunt Senior Editor

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