New guidance released earlier this month by the US Food and Drug Administration (FDA) aims to make it easier for some companies to develop products for so-called "neglected" tropical diseases (NTDs) affecting the developing world.

Background

Tropical diseases are typically not subject to the same levels of investment and research as are other diseases, in part because the markets for those products are generally less affluent, leaving companies less able to obtain a positive return on their investment (particularly if research and development was conducted in regions with higher costs).

Accordingly, tropical diseases can often be left "orphaned" by drug development—that is, left without an adequate supply of treatments or cures.

To help alleviate this dearth of treatments, in 2007 US legislators passed the Food and Drug Administration Amendments Act (FDAAA), which established a new and powerful incentive to help spur tropical drug development: Tropical Disease Priority Review Vouchers.

Under the new incentives, companies that receive approval for a tropical disease treatment are eligible to receive a transferable voucher that allows the bearer to receive six-month priority review status for any future product. Products undergoing priority review are generally given an approval decision—positive or negative—within six months after the applicant's filing date instead of the usual 10.

Under normal circumstances, FDA only grants priority review status to products which fill a treatment void or would otherwise represent a significant advancement compared to existing treatments. Because these reviews cost more than traditional drug reviews, the cost per application is more. However, under the voucher program, any company willing to pay the additional cost of the review may have its product reviewed by FDA. In Fiscal Year (FY) 2014, that fee amounts to $2,325,000—down significantly from the $5,280,000 it cost in FY 2012.

New Guidance

But while FDA has published guidance since 2008 on the voucher program, it is only now finalizing a 2011 guidance on how sponsors should actually go about developing treatments for NTDs.

The final guidance, Neglected Tropical Diseases of the Developing World: Developing Drugs for Treatment or Prevention, is, by FDA's own admission, "basic."

"Pharmaceutical sponsors with experience in drug development will find this guidance to be basic, but we acknowledge that sponsors interested in evaluating investigational drugs for NTDs may have little experience in working with the FDA on drug development issues," FDA explains in the preamble to the guidance.

And true to its word, the guidance document is indeed basic, though useful as an overview of the overall drug development process. The guidance also includes references for prospective developers to seek more detailed information in other guidance documents previously published by FDA or the International Conference on Harmonization (ICH), a regulatory standards-setting body for the pharmaceutical sector.

That said, FDA's guidance does include some interesting nuggets of information about the NTD development process. For example, FDA says it expects that much of the clinical data supporting a drug's safety and efficacy will come from outside the US. That's quite unusual for drugs expected to be used in the US, but FDA notes that it can—and will—approve such drugs so long as they adhere to good clinical practice (GCP) guidelines.

Such sponsors are also "strongly" encouraged to submit an Investigational New Drug (IND) application to FDA, "regardless of where the clinical development occurs, to provide an opportunity for the FDA to offer advice on the development program to ensure that it will be able to support a future New Drug Application (NDA) or Biologics Licensing Application (BLA)."

FDA's guidance also gives an endorsement of adaptive trial designs, which the agency said "may be appropriate to consider for clinical trials of some NTDs." Sponsors considering using adaptive designs—essentially designs which alter a trial once it has already begun in response to emerging evidence—should first speak with FDA, the guidance adds.

Sponsors are also encouraged to seek out FDA's special review programs, such as fast track designation, breakthrough therapy designation, accelerated approval, priority review designation, orphan product designation and qualified infectious disease product designation. All programs afford special incentives, primarily focused around quicker review times, added periods of exclusivity or a reduction in fees.

Neglected Tropical Diseases of the Developing World: Developing Drugs for Treatment or Prevention (FR)