Global Insight Perspective | |
Significance | Committee members voted in support of the vaccine's efficacy for all groups of children under the age of five. However, they were divided on the safety of the vaccine, particularly for children under the age of two. |
Implications | The FDA is expected to issue its decision on MedImmune's supplemental Biologics Licensing Application (sBLA) on 28 May. The decision does not have to follow the committee's recommendation, but given the serious reservations evident in the vote split for younger children it is unlikely to ignore the recommendations in this case. |
Outlook | An FDA ruling in line with the committee's recommendations entails some positives and some negatives for MedImmune. Expanding the approval to include children aged 2-5 would allow the company to target a much wider population. However, the safety issues for children under the age of two—if confirmed by the FDA—will prevent use of FluMist in the six months-two years age group and could dampen sales in the adjacent age groups as well. |
VRPBAC Split on FluMist Safety
Yesterday's meeting of the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) brought mixed results for U.S. biotech MedImmune. Committee members supported the vaccine for all age groups between six months and five years in terms of efficacy. When it comes to safety, however, the outcome was not so clear cut. By a small majority experts felt the clinical data supported safety for children aged 12-59 months without a history of wheezing, but voted against the vaccine’s safety for children aged 6 -23 months regardless of wheezing history. The only age group among the under-fives for which the vaccine was deemed safe by all committee members was children aged 2-5 years, regardless of their history of wheezing.
Outlook and Implications
The advisory committee's recommendations will be taken into account by the FDA when it meets to discuss the sBLA for FluMist on 28 May. The vaccine is so far approved for use in the 5-49 years age group only, and MedImmune has been trying to expand the approval based on new clinical results. The preliminary results, as discussed by Global Insight in February, indicate that the safety data becomes less conclusive for children under the age of two. While there is no statistically significant difference in the rate of wheezing among FluMist recipients compared to those receiving an injectable 'flu vaccine, there is a small positive trend of higher wheezing rates with the intranasal vaccine compared to the injectable vaccine. Global Insight estimated back then that in the absence of new clinical data, FluMist is expected to gain approval for the 2-5 years age group, but that approval for children aged 6-12 months would be subject to significant restrictions (see United States: 16 February 2007: Study Results to Boost FluMist's Fortunes). These estimates now appear to be overoptimistic, as the committee has deemed the risks too high for those aged 6-12 months altogether. The FDA will have the final say on this issue later this month.
For MedImmune, the committee recommendations are as good as could have been expected based on the clinical data. If the FluMist indications are expanded to include children aged 2-5 years, the concern for the company will be that doctors and parents opt for an injectable vaccine for children in the lower part of the newly-approved age group. Also, depending on how strong the warning language on wheezing is in the final FluMist label, there is a high risk that doctors and parents will actively avoid FluMist for all children with a history of wheezing, regardless of the age group.
Development of an intranasal 'flu vaccine—in the presence of established and safe injectable ones—was always going to be a risky endeavour. MedImmune has tried to reduce the risk by conducting extensive clinical studies, but unfortunately the safety profile has not turned out as well as it hoped. This risk will now have to be shared by British drug-maker AstraZeneca, which is in the process of taking over MedImmune (see United States: 23 April 2007: AstraZeneca to Buy MedImmune for US$15.6 bil.).
The next 'flu season will be decisive in terms of boosting FluMist's market presence, as it will be the first when a new refrigerated version of the vaccine (the original version requiring freezing) hits the market. And, if the FDA follows the VRPBAC's advice, it is also expected to be the first 'flu season when FluMist is able to tap the under-fives market. Influenza vaccination is recommended in the United States for children under the age of five, and it is easier to obtain reimbursement from healthcare providers. MedImmune will hope to target at least the under-fives market, considering its approved indications prevent it from being used in elderly Americans—the other age group for which 'flu vaccination is recommended and generally reimbursed.