Fortress falls: Virios flunks fibromyalgia study but claims drug may work in the omicron era

Virios Therapeutics’ antiviral fibromyalgia drug candidate IMC-1 has flunked a midphase clinical trial. But, while the prospect failed to improve pain more than placebo in the overall population, Virios is making the case that it was effective after the emergence of the omicron variant of COVID-19.

Atlanta-based Virios randomized 425 women to receive IMC-1, an oral fixed-dose combination of famciclovir and celecoxib, or placebo in the belief the molecules can inhibit viral replication and thereby treat the pain experienced by fibromyalgia patients. However, after 14 weeks, the weekly average of daily self-reported pain severity scores was similar in the IMC-1 and placebo cohorts.

The failure of IMC-1 to improve pain severity scores versus placebo caused the FORTRESS study to miss its primary endpoint with a p-value of 0.302. Investors responded to the failure by sending Virios’ stock down 68% to $2.78 in premarket trading.

While investors are clearly down on the data, the biotech is yet to give up on the program. Virios’ desire to review the data before updating its plans for IMC-1 reflects a belief that the evolution of the COVID-19 situation during the trial, which enrolled patients from June 2021 to April 2022, may have affected the results. 

Limiting the analysis to the 214 patients enrolled in the second half of the study, “when vaccination rates improved and the less severe omicron variant of COVID-19 became the dominant U.S. strain,” Virios found IMC-1 beat placebo on the pain severity endpoint, delivering a p-value of 0.03. The biotech also linked IMC-1 to improvements on secondary endpoints in the subpopulation. 

“We believe the interplay between different COVID-19 strains and herpes virus activation may be contributing to the differential response we observed in patients enrolled in 2021 versus 2022,” Virios CEO Greg Duncan said in a Sept. 19 release.

All the FORTRESS study sites listed on are in the U.S. Delta was the dominant virus in the U.S. deep into 2021, accounting for 75% of cases in the two weeks up to Dec. 20, although it was rapidly supplanted by omicron thereafter. Omicron would have been dominant for around 50% of the treatment period for participants enrolled at the start of November.

On June 3, 2021, when FORTRESS started, 45% of people in the U.S. were fully vaccinated against COVID-19. The figure had increased to 60% by mid-November, the midpoint of enrollment in the study, and again to 66% at the start of April 2022. As Virios sees it, the transition from delta to omicron and the rise in vaccination rates can explain the FORTRESS failure. Judging by the drop in the biotech's share price, many investors may still need convincing.