Material Event (Form 8-K)

On October 14, 2025, BioXcel Therapeutics, Inc. (the "Company") announced positive results from the correlation study related to exploratory efficacy outcomes from the SERENITY At Home trial. The results, along with the data from the SERENITY At Home trial, will be included in the supplemental New Drug Application (sNDA) submission that is planned for the first quarter of 2026.

The standard method for measuring acute agitation associated with schizophrenia and bipolar disorder is the Positive and Negative Syndrome Scale - Excited Component (PEC) administered by a trained clinician, which was used in the Serenity I & II Pivotal Trials. In order to evaluate BXCL501 for continued clinical effect with repeat dosing in the at-home setting using an exploratory efficacy measurement, the Company, in consultation with FDA, developed the modified CGI-S (mCGI-S) scale, which can be scored by patients and/or caregivers.

The study assessed the correlation between PEC and mCGI-S in this prospective, open label, in-clinic trial in 33 patients. The results demonstrated a strong correlation between the clinician assessments and the patient or caregiver (informant) rated outcomes, providing support for using mCGI-S to assess efficacy in the outpatient setting. A statistically significant and strong correlation between the PEC and mCGI-S with a correlation of ρ=0.89; p<0.0001 for patients and ρ=0.88; p<0.0001 for informants was observed.

There were no serious adverse events reported and the safety profile remains consistent with the IGALMI® label.