Johnson & Johnson (J&J) has announced the discontinuation of its Phase 2 field study evaluating mosnodenvir (formerly JNJ-1802), an investigational antiviral for the prevention of dengue. This decision is part of a strategic reprioritization of the company's communicable diseases research and development (R&D) portfolio.
Mosnodenvir's Development and Prior Studies
Mosnodenvir functions as a pan-serotype inhibitor of the NS4B protein, which dengue viruses utilize to replicate their genetic material. Prior Phase 1 and Phase 2a clinical studies indicated that mosnodenvir was safe and well-tolerated. Specifically, Phase 2a human challenge studies showed that the compound induced antiviral activity against dengue (DENV-3) in humans, compared to placebo.
J&J had previously initiated a Phase IIa, double-blinded, placebo-controlled study of mosnodenvir in patients with confirmed dengue infection, but this trial was eventually discontinued due to enrollment difficulties linked to the COVID-19 pandemic. Additionally, a third mid-stage trial to assess the antiviral activity, safety, and pharmacokinetic profile of repeated mosnodenvir doses against dengue serotype 1 was suspended.
Strategic Shift Away from Infectious Diseases
The discontinuation of the mosnodenvir study aligns with J&J's broader strategic shift away from infectious disease research. In mid-2023, the company revealed the discontinuation of seven infectious disease programs, including several for hepatitis B, alongside candidates for HIV, influenza, and hepatitis D. J&J also exited the respiratory syncytial virus (RSV) vaccine space and terminated the Phase III Mosaico trial for its investigational HIV vaccine regimen due to disappointing data.
Despite this shift, J&J has stated that it will continue to provide its HIV and E. coli vaccines, while work for other infectious diseases, such as tuberculosis, will be folded into Janssen’s global health portfolio.
Dengue Burden and Current Landscape
Dengue is a significant global health concern, with approximately 90 countries reporting cases this year. As of September 5, 2024, the Americas reported an all-time high of more than 11 million cases, according to The Lancet Infectious Diseases. In the United States, there have been 3,613 locally acquired cases as of October 2 reporting, according to the Centers for Disease Control and Prevention (CDC). The incidence rates of vector-borne diseases in the country continue to rise.
Currently, there is one FDA-approved dengue vaccine, Dengvaxia, which is authorized for children aged 9 to 16 who have previously had a laboratory-confirmed dengue infection and live in regions where dengue is prevalent, including certain US territories and associated states. Dengue is considered endemic in US territories of American Samoa, Puerto Rico, and the US Virgin Islands, and freely associated states, including the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau.
Efficacy data from the Phase 2 field study of mosnodenvir will be available once the final data analyses are complete. Study investigators have been notified of the discontinuation, and all participants have completed the study per protocol and will be notified of the results once they are ready.
