Virios Therapeutics’s fibromyalgia program has gained a major boost after the US Food and Drug Administration (FDA) offered positive initial feedback on a Phase III program.

Virios proposed a Phase III program of IMC-1 consisting of two randomized control trials – one long-term safety study, and one pharmacokinetic and food effect study. The FDA gave Virios the initial go-ahead and will provide updated guidance after receiving final data from an IMC-01 toxicology study. Data from the ongoing toxicology study is expected in May 2023.

IMC-1 is a combination of the small molecules famciclovir and celecoxib designed to suppress herpes virus replication. This could reduce fibromyalgia disease symptoms caused by the virus and generate anti-inflammatory effects.

Mixed Phase II data in fibromyalgia

With the Phase III proposal, Virios and regulators are placing faith in a drug candidate that has had a somewhat rocky drug development history. In September 2022, Virios announced that IMC-1 missed the pain score primary endpoint in the 422-patient Phase IIb FORTRESS trial in fibromyalgia (NCT04748705).

However, Virios found that the 214 patients recruited in the second half of FORTRESS did achieve statistical significance along the primary outcome of pain. The company attributed this to improved Covid-19 vaccination rates and the prevalence of less severe Covid-19 variants. In the first half of the study, the greater presence of Covid-19 may have interfered with IMC-01’s mechanism of targeting herpes viral replication.

In the proposed Phase III program of IMC-1, Virios will target fibromyalgia patients who have not yet been in clinical trials. The FORTRESS trial of IMC-001 enrolled only women.

Fibromyalgia is a chronic condition causing widespread pain across the body. The condition has also been linked to long Covid, where significant symptom overlap occurs.