Congress created the priority review voucher in 2007 to incentivize the development of treatments for neglected tropical diseases. Vouchers, which can be transferred or sold, are awarded when a company obtains US Food and Drug Administration (FDA) approval for a drug or vaccine indicated for a neglected tropical disease (Box). They allow sponsors to obtain faster FDA review of a product for any indication, not restricted to neglected tropical diseases, moving the application from the standard 10 months to the priority review timeline of 6 months. This provides valuable earlier access to the US market for those drugs that would have not otherwise qualified for priority review: vouchers have been sold for prices ranging from $67 million to $350 million.2

Box Section Ref ID

Box. Criteria for Neglected Tropical Disease Priority Review Voucher Eligibility Provision of treatment or vaccination of 1 of the following diseasesa: Blinding trachoma

Buruli ulcer

Chagas (added 2015)

Cholera

Dengue

Dracunculiasis

Fascioliasis

Filovirus (added 2014)

Leishmaniasis

Leprosy

Lymphatic filariasis

Malaria

Neurocysticercosis (added 2015)

Onchocerciasis

Schistosomiasis

Soil-transmitted helminthiasis

Trypanosomiasis

Tuberculosis

Yaws

Zika virus (added 2016) Submission to the US Food and Drug Administration as a new drug application or biologics license application Novel drug or biological product (no active ingredient of the drug, including any ester or salt of the active ingredient, may have been approved in any other application) Qualification of a drug or vaccine for priority review on its own merit a The law also awards vouchers for treatments for “any other infectious disease for which there is no significant market in developed nations and that disproportionately affects poor and marginalized populations, designated by order of the Secretary.”1

Since 2007, only 4 neglected tropical disease vouchers have been awarded.2,3 To our knowledge, no one has investigated whether the use of priority review vouchers may have had the intended effect on incentivizing development of drugs and vaccines for neglected tropical diseases. This study evaluated the number of new drugs and vaccines for neglected tropical diseases entering phase 1 clinical trials before and after the voucher incentive was created.

Methods

We identified all compounds entering phase 1 trials between January 2000 and December 2014 using Pharmaprojects, a large commercial database of global pharmaceutical research and development (Informa) that is widely used by researchers, regulators, and industry to track drug development trends.4 This database is one of the most comprehensive of its kind and compiles public and proprietary information about investigational drugs throughout their lifecycle, including press releases, regulatory filings, investor reports, scientific literature, and direct communication with companies. We cross-checked information on trial start dates with AdisInsight (Springer), 1 of the 2 other major commercial databases.

We identified voucher-eligible new drugs and biologics with qualifying indications entering phase 1 trials. To compare trends before and after voucher program creation, a Poisson model was fit that included the count of neglected tropical disease drugs each year as the dependent variable and variables for year before and after 2007 (year of voucher program creation) as the independent variables. The log of the total number of drugs each year was included as a model offset, so that parameters could be interpreted as rate ratios, in which the rate was the proportion of neglected tropical disease drugs each year (R [R Foundation], version 3.3).

Results

Between 2000 and 2007, 32 novel products intended to prevent or treat neglected tropical diseases started phase 1 trials (1.9% of 1704 phase 1 trials), vs 34 products between 2008 and 2014 (1.5% of 2302 trials) (Figure). The proportion of neglected tropical disease drugs among all products in development decreased by 1.74% per year (95% CI, −13.68% to 12.87%) before the voucher was created and decreased by 1.73% per year (95% CI, −12.75% to 10.27%) after the voucher was created.

Discussion

The priority review voucher was not associated with an increase in innovative, early-stage neglected tropical disease product development. Although this analysis did not examine whether the voucher encouraged companies to move compounds already in clinical development into phase 2 and phase 3 trials, any such products would likely have completed development in the last 9 years. The paucity of approved neglected tropical disease products in the last decade suggests the voucher also did not serve as a stimulus for stalled late-stage development. The assessments of novelty used in this analysis were based on publicly available information and may differ from the FDA’s determination.

Companies may not have responded to the voucher incentive because its value is uncertain: the value decreases as more vouchers become available on the market.5 Since 2007, Congress has expanded the number of voucher programs so that vouchers can now also be awarded for new treatments for rare pediatric diseases and medical countermeasures. An improved incentive scheme would reduce the risk of neglected tropical disease product development such as by decreasing the cost of clinical trials to pharmaceutical companies. A public-private partnership could provide financial support to sponsors of neglected tropical disease products. The partnership could be actively managed to ensure reasonable cost and access to the end product, unlike the priority review voucher, which does not require companies to make products widely available to patients.

Section Editor: Jody W. Zylke, MD, Deputy Editor.

Back to top Article Information

Accepted for Publication: May 24, 2017.

Corresponding Author: Aaron S. Kesselheim, MD, Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, 1620 Tremont St, Ste 3030, Boston, MA 02120 (akesselheim@partners.org).

Author Contributions: Dr Kesselheim had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Hwang, Kesselheim.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Jain.

Critical revision of the manuscript for important intellectual content: Hwang, Franklin, Kesselheim.

Statistical analysis: Hwang, Franklin.

Obtained funding: Kesselheim.

Supervision: Kesselheim.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Franklin reports receiving funding from the Patient-Centered Outcomes Research Institute and Merck and consulting for Aetion, a software company. Mr Hwang reports being previously employed by Blackstone and Bain Capital, which has invested in health care companies. Dr Jain reports receiving an award from Merck. No other disclosures were reported.

Funding/Support: This work was supported by the Laura and John Arnold Foundation. Dr Kesselheim is a Greenwall Faculty Scholar and his work is also funded by the Harvard Program in Therapeutic Science and the Engelberg Foundation.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.