In what may be the first reported evidence that a vaccine canbe used to effectively treat a chronic viral infection,researchers using a herpes simplex vaccine made by TheBiocine Company reported Saturday that the treatment cansignificantly reduce the frequency of genital herpes outbreaks.
Biocine is a joint venture of Chiron Corp. of Emeryville, Calif.,and the Swiss pharmaceutical company Ciba-Geigy. Chiron'sstock (NASDAQ:CHIR) rose sharply on the news Monday,gaining $3.75 a share to $58 in heavy trading.
The initial results of a Phase II, placebo-controlled study werepresented by Stephen Straus of the National Institutes ofAllergy and Infectious Diseases (NIAID), who conducted aPhase I trial that detected vaccine-enhanced immuneresponses. Straus spoke at the American Society of ClinicalInvestigators 1993 Annual Meeting in Washington D.C.
The results "validate the therapeutic approach of usingvaccines as a therapeutic, not just a prophylactic," said analystGreg Brown of Vector Securities International Inc.
This is "the first example of a vaccine given post-infection as animmunotherapeutic that has provided a reasonable clinicalbenefit on disease symptoms," added Dino Dina, president ofBiocine of Emeryville.
The experimental vaccine contains recombinant herpes simplexvirus Type II glycoprotein D developed by Biocine. The gD2protein from the virus envelope is a major target for animmune defense against the virus.
The double-blinded, placebo-controlled trial compared theprotein-based vaccine with the alum adjuvant alone. Alum isused to promote the immune response because it draws whiteblood cells to the injection site, where they are exposed to theantigen. Many chronic viral infections have resisted treatmentbecause they only invoke a low immune response by remainingin a cryptic state within the cells they infect.
Offering a treatment for herpes to a large, unsatisfied marketwill "improve quality of life and decrease the chance oftransmission," which only occurs during active outbreaks, saidBrown, who is also a physician.
Ninety-eight patients with a history of having four to 14 HSV-2genital herpes bouts per year received two vaccinations twomonths apart. Over the next 12 months, patients receiving thevaccine had a median of four outbreaks, and control subjectshad six.
Biocine is conducting another Phase II trial, in 550 patients,with an improved vaccine that has two antigens and anexperimental adjuvant, MF59.
"That vaccine generated higher levels of immune response inPhase I studies than did the gD2/alum vaccine," Dina said. "Ifearlier results are confirmed, we will proceed to Phase IIIstudies in both immunotherapy and prevention of genital HSV-2 disease."
Vector's Brown said that Biocine's announcement adds anotherplank to the company's strong platform of vaccines for AIDS,hepatitis C and cytomegalovirus, which avoid reimbursementconcerns of pediatric vaccines. "They are far ahead" ofcompetitors in this area, he said.
Brown also considers Biocine's financing scheme very attractivefor Chiron. Ciba-Geigy is contributing up to $45 million overthree years, while increasing its equity stake in Biocine overthat time.
Chiron will be able to return to 50 percent ownership for a flat$7 million "interest" payment, paying $53 total in 1996, whichallows the smaller company to "essentially lock in a low-interest rate" in a vehicle that resembles an internal off-balance-sheet type of R&D financing.
-- Nancy Garcia Associate Editor
(c) 1997 American Health Consultants. All rights reserved.