13 Going On 50: Pfizer Seeks Adult Indication For Prevnar

Advisory committee might closely scrutinize the requested indication for the 13-valent pneumococcal conjugate vaccine for adults age 50 and up; it is now indicated for children under six years old.

Pfizer may have to brace for advisory committee review and added scrutiny of efficacy claims for its sNDA to extend the use of its pediatric pneumococcal disease vaccine Prevnar 13 to adults age 50 and up.

The company said it expects a 10-month review cycle from the application's submission date, which would yield an action date in October 2011. That could open the vaccine up to review by FDA's Vaccines and Related Biological Products Advisory Committee on Sept. 20-21, one of the tentative 2011 meeting dates for the panel just announced by the agency.

Pfizer said it has filed a corresponding supplemental application with the European Medicines Agency for Prevnar 13 (pneumococcal 13-valent conjugate vaccine [diphtheria CRM197 protein]), and plans to file in additional countries. The requested indication is the prevention of pneumococcal disease caused by any of the 13 serotypes in the vaccine, including pneumonia and invasive disease caused by the Streptococcus pneumoniae.

Pfizer may receive close scrutiny on efficacy in older adults, based on the advisory panel's previous record. In November 2009, the committee judged that Protein Sciences' seasonal influenza vaccine FluBlok had demonstrated efficacy in adults age 18-49, but not in those age 50-64 or age 65 and up (Also see "Protein Sciences "Dumbfounded" After Committee Votes Down FluBlok" - Pink Sheet, 19 Nov, 2009.).

The day before it dealt that blow to Protein Sciences, however, the committee backed approval of a claim that the additional six serotypes in Prevnar 13 as compared to the original product, Prevnar 7, provide added protection against invasive disease (Also see "No Non-Inferiority, No Problem: FDA Advisory Committee Endorses Prevnar 13" - Pink Sheet, 18 Nov, 2009.).

At the same time, the panel was hesitant to endorse a claim that the new vaccine provides protection against otitis media beyond what has been demonstrated for the seven serotypes in Prevnar. Pfizer acquired Prevnar when it merged with Wyeth.

FDA followed up with approval of Prevnar 13 on Feb. 23, and the same day, the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommended that children who already have been fully vaccinated with Prevnar 7 receive an extra shot of Prevnar 13, broadening the market appeal of the newer product (Also see "ACIP Support Of FDA-Approved Prevnar 13 Creates Prospect For Larger Market" - Pink Sheet, 1 Mar, 2010.).

Since then, the product has been a strong, if slightly cannibalistic, contributor to Pfizer, and adult indication is aimed at fueling the growth of this key product. Sales of Prevnar 13 were $521.1 million in the U.S. through the end of October, IMS data show. Prevnar 7 is still on the market as well; Pfizer reported global sales of Prevnar 13 and Prevnar 7 for the first nine months of the year as $1.59 billion and $1.03 billion respectively. Buy comparison, Wyeth reported Prevnar 7 sales of $2.72 billion for the full year in 2008, the last year it reported the sales before it was acquired by Pfizer.

Average analyst consensus estimates compiled by the tracking firm Evaluate Pharma put Prevnar among the top potential revenue generators globally by 2016, at $5.36 billion.

Support From Six Studies

Pfizer's applications to FDA and EMA are based on six Phase III studies that enrolled approximately 6,000 subjects. All studies in the 50-and-up age group have been completed, Pfizer said in an email. However, the company declined to disclose details of data from the studies, which "are expected to be shared in peer-reviewed forums beginning in 2011."

One study listed on the NIH clinical trial registry ClinicalTrials.gov that appears to fit the bill was sponsored by Wyeth and completed in December 2007. It is described as "a Phase III, open-label trial to evaluate the safety, tolerability and immunogenicity of a 13vPnC when administered to healthy Japanese adults aged >= 65 years and 50 to 64 years in Japan who have not received a previous dose of 23-valent pneumococcal polysaccharide vaccine."

The study enrolled 270 subjects at two Japanese sites. The primary outcome measure was immune response to 13 pneumococcal conjugates induced by 13vPnC as measured by serotype-specific opsonophagocytic assay titers 1 month after vaccination, and the secondary outcome measure was safety and immune response (serum IgG antibody concentrations).

-Martin Berman-Gorvine ([email protected])