A US federally funded Phase II challenge trial investigating AbViro’s sole pipeline candidate, AV1, will see 84 patients infected with dengue virus.

The US National Institutes of Health (NIH) has launched a Phase IIa, randomised, double-blind, placebo-controlled trial (NCT05048875) that will expose volunteers to a weakened strain of the virus that the US Centers for Disease Control (CDC) estimates infects approximately 400 million people every year.

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If successful, AV1 could go on to become the first treatment for dengue fever to be approved by the US Food and Drug Administration (FDA). The therapy is described as an investigational human monoclonal antibody therapeutic taken orally.

Typically transmitted via mosquitoes, symptoms of dengue typically include body aches, nausea, vomiting, and fever. While not everyone who gets the virus presents symptoms, the CDC estimates that one in 20 cases escalates to severe illness.

National Institute of Allergy and Infectious Diseases (NIAID) director Jeanne Marrazzo said: “When caring for a patient who is critically ill with dengue, healthcare providers have few options other than providing supportive care. We must find safe and effective therapeutics to provide much-needed relief to people suffering from dengue.”

The announcement follows the World Health Organization’s (WHO) announcement last November that worldwide cases of dengue fever doubled between 2023 and 2024. This is due in large part to climate change making more parts of the world habitable for the Aedes mosquito.

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The Phase II trial of AV1 will see 84 healthy volunteers split into two arms. One will receive an oral dose of AV-1 a day before being infected with the virus. The other will receive the treatment four days after being given the virus. Each group will then be further split to receive 100mg, 300mg, or 900mg of AV-1.

Also known as ‘bone-break fever’, the vast majority of dengue cases are recorded in countries on the equator, but in 2024, the CDC detected cases in California, Florida, and Arizona. The infection is endemic in the US territory of Puerto Rico, with as many as 1,500 cases recorded in 2024. This trial comes as the WHO calls for commitment to combat neglected tropical diseases from member nations as the body faces stark funding gaps.

GlobalData’s Pharmaceutical Intelligence Center details that there are currently only four dengue products marketed globally, with three potential candidates in Phase III trials. Of the marketed options, the largest is Takeda’s Qdenga vaccine, followed closely by Sanofi’s vaccine Dengvaxia. There is currently no cleared treatment for the virus beyond the broad-spectrum antibiotic, doxycycline, which has only seen approval in India. Last year, the dengue fever market was found to have brought in global sales of $310m, that figure is estimated to rise to $1.2bn by the end of 2030.

GlobalData is the parent company of Clinical Trials Arena.

Elsewhere in the field of dengue fever, Island Pharmaceuticals has dosed all participants in the first stage of a Phase II trial investigating its candidate as both a preventative and therapeutic.

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