Inadequate Characterization of Safety Data and Abuse Potential
Severity: criticalInconsistent adverse event (AE) definitions between the MAPP2 protocol and study training materials led to systematic underreporting of 'positive' or 'favorable' effects, which are relevant to abuse potential. This raises critical concerns about the reliability of safety data and the adequate characterization of midomafetamine's safety profile, acute effects, duration of impairment, and signals of abuse potential.
Recommended response: Conduct an independent third-party data audit of all study records, including treatment session recordings, to identify unreported or under-reported adverse events. Revise AE reporting procedures to capture all abuse-related AEs regardless of perceived emotional valence, following FDA guidance on Assessment of Abuse Potential of Drugs.
Failure to Demonstrate Durable Treatment Effect for Chronic Condition
Severity: majorThe MPLONG study, intended to assess durability of effect, suffered from significant design flaws including a single visit, marked variability in timing, potential self-selection bias, and interim therapeutic interventions. Consequently, the data from MPLONG do not provide evidence of a durable treatment effect, which is critical for a chronic condition like PTSD, and fails to inform appropriate long-term drug management.
Recommended response: Conduct a new randomized, double-blind clinical trial to assess the durability of effect. The study design should include blinded long-term follow-up with pre-specified criteria for recurrence of PTSD symptoms and potential retreatment, and monthly follow-up assessments.
Clinical Trial Bias and Interpretability Issues
Severity: majorApproximately 40% of enrolled participants had prior experience with midomafetamine, significantly higher than background use, coupled with high failure rates during prescreening. These factors suggest selection bias and potential expectation bias, limiting generalizability and impacting the interpretability of MAPP1 and MAPP2, thereby precluding substantial evidence of effectiveness.
Recommended response: Design future studies to minimize bias by excluding or minimizing participants with prior MDMA or other psychedelic use, incorporating an assessment of participant expectancy at baseline, assessing both participant and rater/therapist unblinding at the end of the study, and considering the inclusion of a low-dose midomafetamine arm as a control.
Incomplete Laboratory and Cardiac Safety Assessments (Data Gaps)
Severity: minorThe application lacked routine laboratory data (e.g., liver analytes, electrolytes) from Phase 3 studies. The cardiac safety assessment was incomplete, specifically the in vitro hERG assessment was inadequate, and a dedicated cardiac pharmacodynamic study was missing. While not approvability issues at this time, these data gaps must be addressed in any resubmission.
Recommended response: Incorporate routine laboratory assessments at baseline and post-dose, assess vital signs, evaluate major metabolites on hERG current, and conduct a dedicated pharmacodynamic (ECG) study using continuous Holter monitoring covering therapeutic and high clinical exposures.
Recommendations for Future Study Design and Diversity
Severity: infoRecommendations for future clinical trials include characterizing the extent to which psychotherapy contributes to treatment benefit (e.g., using an evidence-based standard of care psychotherapy, considering a factorial study design with a no-psychotherapy arm) and improving the diversity of the study population.
Recommended response: Consider factorial study designs to assess psychotherapy contribution and refer to the draft guidance on Diversity Action Plans to improve enrollment of participants from underrepresented populations in clinical studies.
