The Drugs for Neglected Diseases initiative and Medecins Sans Frontieres are calling into question the validity of the US Food and Drug Administration’s present priority review voucher system, citing the case of the $125 million Knight Therapeutics has recently received from Gilead Sciences.

In particular, DNDi and Medecins Sans Frontieres are turning up the heat on Knight, which got the PRV in March in connection with approval for its leishmaniasis drug Impavido (miltefosine) and the firm’s ex-US distribution and manufacturing partner Endo. They describe it as “a vital drug in the currently fragile treatment arsenal for both visceral and cutaneous forms of leishmaniasis, a disease with over 1.3 million new cases and up to 40,000 deaths each year from the visceral form.”

The NGOs argue that the R&D for miltefosine use in treating leishmaniasis "was largely conducted in the mid-1990s by the WHO/TDR (Special Programme for Research and Training in Tropical Diseases) and partners, with private and public funding". Since then, DNDi and partners have invested in studies testing the drug.

DNDi and MSF claim that Knight nor Endo (and its Paladin unit) has invested significantly in the R&D for the drug, yet the former “will now benefit to the tune of $125 million” after selling its PRV to Gilead earlier this month. They say access to miltefosine in low- and middle-income countries has been inconsistent over recent years, “with drug shortages, large minimum purchase requirements by the manufacturers and a lack of response to public tenders where the drug was much needed, including in endemic countries such as India”.

Cost disclosure requested

DNDi and MSF have now urged Knight and Endo to take a number of steps, such as disclosing the actual cost of production of the drug and asked them to price it “at-cost or with a minimal profit margin to ensure sustainable production”. They have also asked the drugmakers to support additional clinical studies “to optimise the use of miltefosine, including pharmacovigilance [and] dosing in children”.

They go on to argue that “the blatant hindrances to patient access to miltefosine for this neglected disease should be examined to the same extent as, and in conjunction with, the important economic benefit that Knight has received for selling the PRV for R&D that the company did not carry out”.

MSF and DNDi state that “the PRV mechanism, which aims to stimulate or at least reward drug development for neglected diseases, currently contains no access provisions and fails to ensure that only entities that invested in R&D are awarded the voucher”. They note that with the PRV system currently being amended by the US Congress to extend its applicability to Ebola, “the opportunity to improve this important incentive mechanism should not be missed”.

There are currently only four drugs included in the World Health Organisation’s Essential Medicines List for the treatment of leishmaniasis globally, including miltefosine.