A World Health Organization review of the dengue therapeutic pipeline has identified resomelagon as one of six candidates with sufficient supporting efficacy data to warrant further clinical development. The molecule's developer is Sweden-based SynAct Pharma AB (Nasdaq Stockholm: SYNACT). The review, published in Lancet Microbe, is intended to guide regulators, funders, and developers toward accelerated product development in a disease that WHO reported affected more than 14 million people in 2024. The WHO framework distinguishes treatments for non-severe dengue, where reducing symptom duration and preventing progression are key goals, from therapies for severe disease, where reducing organ failure and mortality is the priority.
Resomelagon is the only host-directed therapy among the six named candidates, with the five others being small-molecule antivirals and monoclonal antibody antiviral programs. SynAct argues that this could allow treatment later in the disease course than direct antivirals, which are generally expected to work best early in infection. Resomelagon selectively activates the MC1 and MC3 melanocortin receptors to promote resolution of active inflammation rather than broadly suppressing immune activity.
The ongoing Phase II RESOVIR-2 study — a randomized, double-blind, placebo-controlled trial conducted in Brazil under the leadership of Professor Mauro Teixeira at the Federal University of Minas Gerais — is evaluating resomelagon in dengue patients with reduction in symptom duration as the primary endpoint. No efficacy or safety data have been reported; results from Part 1 are expected in 2026 pending feedback from regulatory authorities. The WHO review separately identified symptom resolution as an appropriate and clinically meaningful endpoint for non-severe dengue, an alignment SynAct said supports its development approach.