4DMT Announces Positive 2-Year Data from PRISM Phase 2b Clinical Trial in a Broad Wet AMD Population

4D Molecular Therapeutics (Nasdaq: FDMT, 4DMT or the Company), a leading late-stage biotechnology company advancing durable and disease-targeted therapeutics with potential to transform treatment paradigms and provide unprecedented benefits to patients, today announced positive 2-year data from the PRISM Phase 2b clinical trial evaluating 4D-150 in a broad wet age-related macular degeneration (wet AMD) population. The data were presented by Carl Awh, M.D., FASRS, Tennessee Retina, in an oral presentation titled “2-Year Follow Up: PRISM Phase 2b Clinical Trial Evaluating Investigational 4D-150, an Intravitreal Gene Therapy, in a Broad Neovascular AMD Population” at the 44 th Annual Scientific Meeting of the American Society of Retina Specialists (ASRS).

The Phase 2b trial enrolled 45 patients at two dose levels of a single intravitreal dose of 4D-150 (3E10 and 1E10 vg/eye); 3E10 vg/eye was chosen as the dose for the 4FRONT Phase 3 clinical trials The Phase 2b overall cohort enrolled patients with broad disease activity (n=30 dosed with 3E10 vg/eye and n=15 dosed with 1E10 vg/eye) The Phase 2b cohort subgroup comprised recently diagnosed patients (diagnosed within 6 months, n=15 at 3E10 vg/eye), which is most comparable to the population enrolled in the 4FRONT Phase 3 clinical trials

Consistent maintenance of best corrected visual acuity (BCVA) Consistent control of central subfield thickness (CST) as measured by optical coherence tomography Consistent, durable and clinically meaningful reduction in treatment burden: Overall cohort: 78% overall treatment burden reduction (2.7 mean supplemental injections per patient vs. 12.0 injections projected with on-label aflibercept 2 mg Q8W) Recently diagnosed subgroup: 87% overall treatment burden reduction (1.6 mean supplemental injections per patient vs. 12.0 injections projected with on-label aflibercept 2 mg Q8W) Dose response maintained throughout 2 years in favor of the Phase 3 dose

4D-150 continues to be well tolerated: Intraocular inflammation: As previously reported, within approximately the first 6 months (28 weeks) post-4D-150 dosing, 2.8% (2 of 71) of patients had 4D-150-related 1+ (mild) intraocular inflammation (IOI) (SUN/NEI scales), which were transient 1+ vitreous cells noted at a single timepoint Following the first 28 weeks post-4D-150 dosing, no new cases of inflammation with 2 to more than 4 years of follow-up on all patients as of the data cutoff No 4D-150-related hypotony, endophthalmitis, vasculitis, occlusive/non-occlusive retinal vasculitis or choroidal effusions observed to date