Virios Therapeutics, Inc. announced topline results from its FORTRESS (Fibromyalgia Outcome Research Trial Evaluating Synergistic Suppression of Herpes Simplex Virus-1 (“HSV-1”)) study of oral IMC-1 for the treatment of FM. Overall, the FORTRESS study did not achieve statistical significance on the prespecified primary efficacy endpoint of change from baseline to Week 14 in the weekly average of daily self-reported average pain severity scores comparing IMC-1 to placebo (p=0.302). However, analysis of the data suggests a bifurcation of response based on the timing of patient enrollment in the FORTRESS trial.

During the first half of the trial (June 2021 to November 2021), for the patients who were enrolled (n=208) when the Delta variant of COVID-19 was the dominant strain in the U.S., IMC-1 demonstrated no improvement versus placebo-treated patients. Conversely, duringa the second half of the trial (November 2021 to April 2022), for the patients who were enrolled (n=214) when vaccination rates improved and the less severe Omicron variant of COVID-19 became the dominant U.S. strain, IMC-1-treated patients demonstrated a statistically significant improvement on the primary pain reduction endpoint (p=0.03) at Week 14, as well as a statistically significant improvement in the key secondary PROMIS Fatigue assessment (p=0.006) and the Fibromyalgia Impact Questionnaire-Revised (FIQR) symptoms domain score (p=0.015). IMC-1 was well-tolerated overall, with only 4.6% of IMC-1 treated patients dropping out due to adverse events, as compared with 8.1% of placebo treated patients.

No adverse event category in the IMC-1 group exceeded a 4% rate with the exception of COVID-19 infection. Overall discontinuations were 18.5% in the IMC-1 treated group versus 23% in the placebo treated group. Patients in the FORTRESS trial were randomized one-to-one to either IMC-1 or placebo and patient background demographics and baseline pain scores were well matched.