Definium Therapeutics (DFTX) investor relations material

DT120 filing and regulatory strategy

• Three Phase III studies read out positive over the summer: two in GAD and one in MDD; an NDA is planned for H1 2027, with the goal of pursuing both indications.

• FDA discussions on filing format continue; the priority is securing both labels, and the completed GAD evidence was described as adequate for an NDA submission on its own.

• A second Phase III MDD study is enrolling well; results could provide additional evidence on the discussed timelines if FDA seeks another study.

• In each indication, one study compares placebo with 100 mcg DT120; the other adds a 50 mcg control arm at half the participant target to assess whether effects persist across study designs.

• Nine-month open-label extensions are underway, allowing up to four additional doses; PTSD studies are planned to start in 2027, alongside ongoing data collection including ASCEND.

DT120 treatment and safety approach

• Development was designed to generate evidence for specific label and REMS arguments, including administration and observation; management expects DT120’s characteristics to be assessed individually by FDA.

• DT120 is not intended for prophylactic use; the anticipated approach is to treat when patients worsen and use the minimum amount needed to maintain response.

• Prior response to DT120 predicted later response, while additional doses produced improvement for some patients who had not responded to the first or second dose.

DT402 autism program

• DT402 is R-MDMA in development as a daily treatment for ASD; its proposed effects on social and emotional awareness and communication differ from the stimulant-like effects attributed to the S enantiomer.

• In a five-person open-label cohort, all participants showed a consistent signal associated with drug exposure; the six-hour assessment day tracked effects as drug levels rose and fell, supporting further development.

• Initial studies focus on people with preserved language, with plans to explore more profound ASD deficits; potential use may range from as-needed to daily dosing.

• Development will use established measures while engaging FDA on measuring daily function and life experience; study-design concepts are being prepared for public discussion.

• Cardiac valvulopathy is the main theoretical safety concern discussed; the association with racemic MDMA was characterized as uncertain, and R-MDMA is expected to reduce some toxicity attributed to racemic MDMA.