FDA’s tropical disease priority review voucher program may find new popularity thanks to the global fight against Ebola.

Changes in a pending Senate bill would harmonize the program with its newer sister program for pediatric rare diseases by making the voucher easier to redeem and likely more attractive to sponsors.

Senate Health, Education, Labor and Pensions Committee members moved S. 2917 to the floor by voice vote during a Nov. 19 executive session.

Committee Ranking Member Lamar Alexander, R-Tenn., said after the hearing that he hoped the Senate could pass the bill before it adjourns in December for the holidays.

A bill making the same changes, H.R. 5729, also has been introduced in the House, but has not been considered by the Energy and Commerce Committee yet.

FDA can award a priority review voucher to a sponsor that develops a treatment for a designated tropical disease or rare pediatric disease. The voucher, which also may be sold, allows the holder to gain a priority review for any application it chooses.

The bill’s headline function is to add Ebola to the list of eligible diseases for the tropical disease PRV, but likely more important are the technical changes that it would make to the program.

One would cut the notification time that a sponsor must give FDA prior to redeeming a voucher. Instead of requiring a full year advance notice, the agency would have to be told 90 days before the application is submitted, according to the bill.

It also would adjust language allowing voucher transfers to state “there is no limit on the number of times” a voucher may be transferred.

FDA had interpreted the legislative language creating the tropical disease voucher program in 2007 FDA Amendments Act to mean only one transfer or sale was allowed.

Both issues had been well-known problems that some thought reduced its popularity.

The proposed changes in the Senate bill also would harmonize the tropical disease PRV program with the pediatric rare disease PRV program, which was created in the 2012 FDA Safety and Innovation Act.

FDA recently issued draft guidance on the rare pediatric disease PRV program offering flexibility on trial design (see related story, [A#00141124009]).

So far only a few tropical disease vouchers have been awarded. One was redeemed by Novartis AG for a faster review of Ilaris (canakinumab), but the product received a “complete response” letter in 2011 Also see "Novartis Takes Stock Of Ilaris For Gout Following FDA's Complete Response Letter" - Pink Sheet, 29 August, 2011..

The result, along with the requirements, may have soured sponsors on the program. There had been questions about how much a voucher was worth Also see "Priority Review Voucher Value Still Confounds, But Remains An Incentive For Sponsors" - Pink Sheet, 21 September, 2011..

The rare pediatric disease PRV program took off much faster. BioMarin Pharmaceutical Inc. received the first voucher awarded upon approval of its Morquio A syndrome treatment Vimizim (elosulfase alfa) and a few months later sold it to Sanofi and Regeneron Pharmaceuticals Inc. for $67.5 million Also see "How Much Is A Priority Review Worth? $67.5 Million, Sanofi/Regeneron Say" - Pink Sheet, 11 August, 2014..

The popularity of the rare pediatric disease PRV program also may have changed some sponsors’ minds about the tropical disease program, even though program harmonization is pending.

Knight Therapeutics Inc. received a tropical disease voucher upon approval of the Leishmaniasis treatment Impavido (miltefosine) in March. The company announced Nov. 19 that it had sold the voucher to Gilead Sciences Inc. for $125 million (see related story, Also see "Priority Review Weirdness: Tropical Voucher Sells For More; Owner Says It’s Worth Less" - Pink Sheet, 24 November, 2014.).

FDA Can Expand Disease List On Its Own

The Senate bill would add filoviruses, some of which cause Ebola, to the list of diseases where treatments are eligible for a voucher. Among the 16 in the existing list are cholera, malaria and tuberculosis (see chart at end of story).

Interestingly, the law allows FDA some flexibility in determining whether another condition would qualify for a voucher. In addition to the diseases mentioned, it states “any other infectious disease for which there is no significant market in developed nations and that disproportionately affects poor and marginalized populations.”

FDA may be able to argue Ebola fits that definition. FDA said in a Nov. 20 email that adding a disease using that provision would require notice-and-comment rulemaking. Passing legislation would be faster and also allow the other changes to be made, which would make the voucher more desirable.

President Obama has requested $6.18 billion in emergency appropriations for Ebola-related activities, including $25 million for FDA to evaluate and approval Ebola drugs.

Multiple government agencies continue to work with industry to develop new Ebola treatments. House Energy and Commerce Committee members also questioned government officials during a recent hearing about efforts to work with industry on expedited product development ([A#14141119004]).

Another Incentive For Vaccine Developers

Adding Ebola to the list of voucher-eligible diseases also would add an incentive for vaccine developers, which do not have access to all the perks available to those developing disease treatments.

FDA has said Ebola vaccines likely would not qualify for orphan drug designation, except in special cases, unlike a treatment for the disease, because it would likely be given to many more people Also see "Ebola Treatments Could Be Orphan Candidates – But Vaccines, Probably Not" - Pink Sheet, 27 October, 2014..

A number of companies already have Ebola treatments and vaccines in their pipelines.

Regeneron has indicated it soon will have a monoclonal antibody candidate ready for animal testing ([A#14141112006]).

Others also are working on vaccines for the virus, several of which are in the early stages of development ([A#00140811015]).

Tropical Disease Priority Review Voucher Eligible Conditions
Tuberculosis	Malaria
Blinding Trachoma	Buruli Ulcer
Cholera	Dengue and Dengue Haemorrhagic Fever
Dracunculiasis	Fascioliasis
Human African Trypanosomiasis	Leishmaniasis
Leprosy	Lymphatic Filariasis
Onchocerciasis	Schistosomiasis
Soil Transmitted Helminthiasis	Yaws
Any other infectious disease with no significant market in developed nations that disproportionately affects poor and marginalized populations, designated by regulation
Source: 2008 FDA draft guidance

Ebola Drugs Take Center Stage In Review Voucher Bill, But Real Value May Be Harmonization

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