CONNAUGHT SEEKING ProHIBIT USE FOR TWO MONTH OLDS

CONNAUGHT SEEKING ProHIBIT USE FOR TWO MONTH OLDS in a supplemental Product License Application filed recently for the Haemophilus influenzae b conjugate vaccine. The company met with FDA at the end of August to discuss the filing, which is based entirely on Connaught's two-year Finnish study involving 120,000 children. An NIH-sponsored Alaskan study in the two to 18 month-old population was not involved in the application. The Finnish study, conducted by the National Public Health Institute in Helsinki, was the basis for ProHIBIT's December 1987 approval for use in children 18 months or older ("The Pink Sheet" Jan. 4, p. 5). The second generation Haemophilus b conjugate vaccine has largely replaced polysaccharide vaccines, which were found to be 50% less effective in immunogenicity studies and required a booster for full immunization. Connaught is in a race for the two month indication with Merck and Praxis. Both companies have Haemophilus b conjugate vaccines in ongoing trials in the U.S. for the under-18 month population. Reportedly, 46% of the Haemophilus influenzae type b disease in the U.S. occurs in six to 17 month infants. The Praxis vaccine clinicals include a study of 5,000 infants in California and 15,000 in Finland. In both trials infants are being given four doses of the vaccine at intervals of 2, 4, 6 and 18 months. Merck is conducting large-scale U.S. studies with its PEDVAX-HIB vaccine in California and St. Louis. More than 1,700 children have been given the vaccine down to two months of age, Merck said. Merck anticipates approval of PEDVAX-HIB for use in infants down to 12 months in early 1989. Results of the Finnish trials with ProHIBIT were presented in late October at the 28th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Los Angeles. In an open field trial of 120,000 children ages 3, 4, 6 and 14 months, ProHIBIT was found to have 87% efficacy after three doses, and 100% after four doses, or 93% efficacy in children six to 24 months of age. The Alaskan study also was presented at the ICAAC conference. The prospective randomized double-blind placebo controlled trial involved 2,113 native Alaskan infants. The study found that the vaccine was 25% effective after one dose at two months, 0% after two doses at two and four months, and 37% effective after the third dose at six months. The researchers concluded that "despite earlier reports of >90% protection with PRP-D ]ProHIBIT[ vaccine in children immunized <6 months of age, we were unable to demonstrate a significant protective benefit in this age group." Several factors may prove to be obstacles for Connaught's ProHIBIT vaccine. Last November, FDA's Vaccines and Related Biological Products Advisory Committee suggested the need for a continental U.S. study with the Haemophilus b conjugate vaccine prior to approval ("The Pink Sheet" Nov. 30, 1987, p. 4). Both Praxis and Merck are conducting U.S. trials in the infant population. In addition, the Alaskan study could also be a drawback for ProHIBIT, as FDA will certainly look at the study in its review of the application. However, Connaught explains that the NIH study is not conclusive, having been conducted with an earlier version of the conjugate vaccine. Finally, the Finnish study starts at three months of age while the company is asking for an indication down to two months. Connaught filed a PLA on Nov. 9 for a new indication for the company's tuberculosis vaccine, bacillus Calmette-Guerin (BCG) Pasteur strain, in the treatment of superficial bladder cancer/carcinoma in situ. If approved, the immunotherapeutic product will be Connaught's first foray into the cancer drug market. The BDG submission is based on a five-year study with 440 patients conducted by the Seattle, Wash.-based Southwest Oncology Group. Given to patients after surgical removal of bladder tumors, BCG has been found to prolong the period between tumor recurrences which occur in more than half the cases following surgery. According to the company, 35,000 to 50,000 patients come down with new cases of bladder cancer each year, with 70% considered superficial.