Neurogene (NGNE) investor relations material

Program overview and clinical progress

• Lead program NGN-401 targets Rett syndrome, a severe neurological disorder with high unmet need and a patient population of 15,000–20,000 in the US and Europe.

• NGN-401 is in a phase III registrational trial (Embolden), with enrollment expected to complete in Q2; high demand and rapid site activation reported.

• Breakthrough Therapy designation was granted based on encouraging phase I/II data, including patient-level and video evidence of efficacy and safety.

• Phase I/II data show consistent, time-dependent, multi-domain improvements in developmental milestones, with no plateau observed at 12 months.

• Long-term follow-up is ongoing, with the first patient approaching a three-year assessment, and stakeholders are keenly interested in durability data.

EXACT platform and differentiation

• EXACT platform enables regulated gene expression using a microRNA-based safety valve, preventing both under- and over-expression of the MECP2 transgene.

• This regulation is critical, as both insufficient and excessive MECP2 are harmful in Rett syndrome.

• The platform aims to avoid toxicity seen with unregulated vectors and supports cell-by-cell control of gene expression.

Clinical outcomes and patient impact

• Patients in phase I/II gained 23 to 35 developmental milestones, with improvements deepening over time and across multiple domains (motor, hand function, communication).

• Gains are clinically meaningful, with examples including improved self-feeding, following instructions, and increased independence.

• Clinician Global Impression of Improvement (CGI-I) scores align with milestone gains and sometimes precede them, providing additional rigor.

• No plateau in skill gains observed up to 12 months; ongoing follow-up will assess longer-term outcomes.