Viagene Inc. said Friday that it's been given the go-ahead forPhase I clinical trials of its HIV immunotherapeutic, making itthe first company to receive FDA clearance for a therapeuticgene transfer product in humans under a commercialinvestigational new drug application (IND).
The notification was not a complete surprise. The FDA's vaccineadvisory committee recommended earlier this month thatViagene be allowed to conduct the trials.
"This is a significant step forward not only for Viagene, but forgene transfer technology," said Robert T. Abbott, president andchief executive officer of the privately held San Diego company."It really establishes what the FDA's position is on genetransfer technology. ... This is the blueprint."
Officials of other gene therapy companies agreed that theapproval marked a big step for the field of gene therapy,although one, at Immunex Corp.'s Targeted Genetics unit,quibbled with Viagene's claim to obtaining the first"commercial IND" for a gene therapy procedure.
Viagene's initial trial will involve 12 HIV-positive patients withCD4+ counts exceeding 500, Abbott said. The company said thepatients will be in early stages of HIV infection and that theywill look like healthy individuals. The company's preclinicaldata suggests that its immunotherapeutic could be effectiveagainst all strains of HIV, so there will be no selection ofpatients based on strains, Abbott said. A specific site for thetrial has yet to be chosen, but it will be in Southern California.
Phase I results, aimed at demonstrating safety of theprocedure, should be available by late 1993, Abbott said. Givenpositive Phase I data, Phase II results could be available in late1994, and Phase III trials could end sometime in 1995.
The FDA's approval was "further evidence of how quickly thearea of gene therapy is progressing," said Samuel F. McKay,chairman of TargeTech Inc. of Meriden, Conn. His companygained notice last week in the Journal of Biological Chemistryfor developing a liver-targeting technology.
"The more trials that are approved for gene therapy, the betterit is for the rest of us," said H. Stewart Parker, president andchief executive officer of Targeted Genetics Corp., a unit ofImmunex Corp. in Seattle.
However, she contends that Targeted Genetics received the firstcommercial IND for a human gene therapy trial last February -- for AIDS patients receiving bone marrow transplants fortreatment of lymphoma.
Abbott said Targeted Genetics' procedure should not currentlybe considered anything more than a physicians' IND, whichrequires for approval less intensive toxicology study andquality control standards than a commercial IND. In its currentform, Targeted Genetics' gene therapy is not intended as apotential commercial product, a point that Parker concedes.
However, she said that Targeted Genetics plans tocommercialize a later version of the gene therapy.
Traditionally, a commercial IND was distinguished from aphysician's IND on the basis of who was lists as the sponsor onthe application. A commercial IND usually lists a company orcommercial group, and a physician's IND listed one or moredoctors. Abbott said in the case of gene therapy, he has beentold by FDA officials that in gene therapy the distinctionbetween the two types of INDs is based on their ultimate use.
Preparing Viagene's immunotherapeutic starts with cells takenfrom a patient by means of a small skin biopsy. Those cells arethen treated with a non-infectious retroviral vector to achieveintracellular expression of a gene sequence that codes forspecific antigenic HIV proteins. It takes from four to six monthsto produce sufficient treated cells, which are then re-administered to the patient with the intention of provoking avigorous immune response
Construction was completed this month at Viagene on twospecialized production facilities for the immunotherapeutic,which are now being validated, Abbott said.
"This is the first of many hurdles in commercializing a productto treat HIV," he said. "However, we are optimistic because ofour positive preclinical data."
-- Ray Potter and Steve Payne BioWorld Staff
(c) 1997 American Health Consultants. All rights reserved.