CONNAUGHT AND LEDERLE ACELLULAR PERTUSSIS VACCINES IN PHASE III FOR USE IN CHILDREN UNDER SIX MONTHS; EUROPEAN TRIALS TO INCLUDE OVER 38,000 INFANTS

Connaught Labs and Lederle each have begun Phase III trials for the acellular pertussis (whooping cough) component of their diphtheria-tetanus-pertussis (DTP) vaccines in children under six months of age, the National Vaccine Advisory Committee was told at its April 21 meeting. The Connaught trial, which is being conducted under the aegis of the National Institute of Allergy & Infectious Diseases, was recently initiated in Stockholm, NIAID Microbiology and Infectious Diseases Division Director John La Montagne, PhD, informed the committee. In the first phase of the trial, "approximately 10,000 infants will be randomized into four arms," he explained. The four arms include two vaccines with an acellular pertussis component (a Connaught pentavalent and a SmithKline Beecham bivalent), one with a whole cell component and one that does not include the pertussis element. The infants will be immunized "using the U.S. schedule," La Montagne said, which is "the two, four and six month schedule." SmithKline is developing the vaccine for European sales, but it also is exploring the possibility of entering the U.S. market. FDA's Vaccines & Related Biological Products Advisory Committee concluded on Nov. 12 that the acellular pertussis component of Connaught's DTP vaccine is safe and effective for the fourth and fifth, or booster doses in children who have received three or four doses of a DTP vaccine containing a whole-cell pertussis component. The approval of the acellular pertussis component is pending at FDA. Recruitment of 10,000 infants is under way, La Montagne said, and the first phase of the trial is expected to be completed "in approximately 15 to 18 months." Following completion, the trial is expected to add approximately 20,000 infants for a total "in excess of 30,000," La Montagne said. The second phase of the trial will employ only the three vaccines that include the pertussis component. In response to a committee question about the decision to drop the placebo arm, La Montagne answered: "We have looked very carefully at the statistical implications of that and are quite comfortable that we do not pay a statistical penalty." La Montagne mentioned that Lederle is performing a trial in Munich of its acellular vaccine. In a April 22 statement, the company explained that active recruitment of 8,000 infants is under way and is expected to be "substantially" completed by the end of 1992. The Lederle trial, which is testing the efficacy of its acellular pertussis vaccine in infants of two, four and six months of age, has three arms, including vaccines with an acellular component, a whole cell component and no pertussis component. Lederle's acellular component will be marketed as Acel-Imune. It was approved by FDA for booster use on Dec. 17. Although fourth dose boosters are for children of approximately 18 months, current labeling for the product states that "the administration of Acel- Imune may be considered for children as young as 15 months of age when it is expected that the child will not return at 18 months ...although studies in this age group have not been completed ("The Pink Sheet" Dec. 23, 1991, T&G-1). Institut Merieux, of which Connaught is an affiliate, is performing a third trial in Senegal, La Montagne told the committee. He added that it appears that Merieux will finish the trial "around 1995." One committee member asked why no test is being performed in the U.S. La Montagne explained that while 6% of children in Sweden come down with pertussis, only 3,500 cases per year are reported in the U.S. In a press release announcing the approval of Acel- Imune, Assistant Secretary for Health James Mason, MD, said that while the whole-cell vaccine has proved to be very effective, it is associated with a high incidence rate of side effects such as sore arms and fever. Vaccines with acellular pertussis components have shown reduced side effects.