Slide 1: RP-A501 Danon Disease Program Update
RP-A501 Danon Disease Program Update © 2026 Rocket Pharmaceuticals Rocket Pharmaceuticals October 6, 2026
Slide 2: Disclaimer
DISCLAIMER 2 © 2026 Rocket Pharmaceuticals This presentation contains forward-looking statements concerning Rocket’s future expectations, plans and prospects that involverisks and uncertainties, as well as assumptions that, if they do not materialize or prove incorrect, could cause actual results to
Slide 3: RP-A501 Danon Disease Program Update: Compelling development path
3 © 2026 Rocket Pharmaceuticals RP-A501 Danon Disease Program Update Compelling development path: $1B+ commercial opportunity Updated Phase 1 data Evidence of disease reversal or stabilization up to 7 years post RP-A501 Initial Phase 2 data Preliminary efficacy up to 36 months data from Cohorts 1-3
Slide 4: Catastrophic in males, with rapid progression and early mortality
4 Catastrophic in males, with rapid progression and early mortality Danon Males Rapid Decline from Symptom Onset to End-Stage Heart Failure2-4 Illustrative; derived from natural history registries & cohorts 5 10 15 Age (years) 20 Cardiac Symptom Onset Diagnosis Loss of cardiac function Leads to end-
Slide 5: Patient & Family Voice: Transplant-Free Survival Matters
5 PATIENT & FAMILY VOICE I thought it would be for a couple days. But that turned into eight months.” Mother of Danon patient - deterioration and mechanical support while awaiting a donor heart I’d lost both my mum and brother as they waited for transplants.” Danon patient and emergency HTx recipien
Slide 6: Danon Disease Biology is Exceptionally Suited to LAMP2B Gene Addition
Danon Disease Biology is Exceptionally Suited to LAMP2B Gene Addition A clear molecular defect. A direct therapeutic approach. A measurable path from biology to clinical impact. DANON DISEASE: LAMP2B deficiency LAMP2 Gene Addition: Restores Cellular Recycling Diseased cardiomyocyte cellular injury,
Slide 7: Phase 1 and Phase 2 Study of RP-A501 in Danon Disease
7 Phase 1 and Phase 2 Study of RP-A501 in Danon Disease Global, single-arm, Pivotal Phase 2 Trial of RP-A501 ongoing; 12-Patients aligned with FDA IM, immunomodulatory regimen; LAMP2, lysosome-associated membrane protein 2; LTFU, Long-term follow-up; LV, left ventricular; LVMI, left ventricular mass
Slide 8: LAMP2 protein expression by biopsy over time
8 Pre-infusion Visit 0 Post-infusion Visit 1 Post-infusion Visit 2 Post-infusion Visit 3 6 7 6.7 × 1013 GC/kg Pediatric, N=2 M12 M24 M36 100 µm M12 M24 M36 100 µm 2 3 6.7 × 1013 GC/kg Adult/adolescent, N=3 M12 M24 M36 100 µm M9 M24 M36 †Reflects 9M visit biopsy as 12M biopsy not performed. *Grade 0
Slide 9: Phase 1 patient-level cardiac outcomes
9 Improved Stabilized Wor sened © 2026 Rocket Pharmaceuticals Cohort Patient Age at Most RV (y) Most Recent Visit (m) Δ LVMI,* BL to RV (g/m2.7) Δ IVSd, BL to RV (mm) Δ LVPWd, BL to RV (mm) Δ NT-proBNP, BL to RV (ng/L) Δ cTnI,† BL to RV (ng/mL) Δ NYHA Class Δ KCCQ-12, BL to RV 1:Low Dose Adult/ Adol
Slide 10: Improved or Stabilized Cardiac Biomarkers and LV mass in RP-A501 Patients
10 Improved or Stabilized Cardiac Biomarkers and LV mass in RP-A501 Patients Differs significantly from expanded natural history data BNP (pg/ml) Age [years] N = 22 patients r2= 0.846 LV mass (g) Age [years] BNP increases by 42.17 ± 18.46 pg/mL per year in untreated Danon males* LV Mass increases by
Slide 11: RP-A501 Phase 1 Summary
11 -16% -14% -18% -11% -32% -15% RP-A501 Phase 1 Summary LAMP2 expression and LVMI improvements seen as early as 6 months post RP-A501 * Where possible, cardiac MRI assessments shown (patients 1, 4, and 7); otherwise, echocardiogram data presented. † Utilized 18 m data when 12m assessment was not do
Slide 12: RP-A501 Pivotal Phase 2 Trial Design
12 RP-A501 Pivotal Phase 2 Trial Design Pivotal, global, single-arm, open-label trial1 FDA, US Food and Drug Administration; hsTnI, high-sensitivity troponin I; LAMP2, lysosome-associated membrane protein 2; LV, left ventricular; LVMI, left ventricular mass Index; IM, immunomodulatory; NYHA, New Yor
Slide 13: Phase 2 patient-level cardiac outcomes
13 BL, Baseline; cTnI, cardiac troponin I; LAMP2, lysosome-associated membrane protein 2; IVSd, Interventricular Septum in diastole; KCCQ, Kansas City Cardiomyopathy Questionnaire; LV, Left Ventricle; LVEF, Left Ventric ular Ejection Fraction; LVMI, Left Ventricular Mass Index, LVPWd, Left Ventricul
Slide 14: Modified Protocol Delivers Favorable Pivotal Cohort Safety Profile
Modified Protocol Delivers Favorable Pivotal Cohort 4 Safety Profile aPatients 2-3, 2-4 and 2-6; bPatient 2-8. GGT, Gamma-glutamyltransferase; IM, immunomodulatory; TEAE, Treatment Emergent Adverse Events Phase 2 Preferred Term (Grade ≥3) Cohorts 1 & 2 (n=4) Cohort 3 (n=2) Cohort 4 (n=3) Subject wit
Slide 15: No Evidence of TMA, CLS, or Other Severe Complement-Mediated Toxicities in Cohort 4
No Evidence of TMA,CLS, or Other Severe Complement-Mediated Toxicities in Cohort 4 Platelets and Terminal Complement Complex (sC5b9) of the initial 3 patients up to 3 months post-treatment CLS, Capillary Leak Syndrome; sC5b9, soluble C5b9; TMA, Thrombotic microangiopathy ‡ ‡ A decrease in platelet c
Slide 16: RP-A501 Demonstrated Durable Efficacy with a Tolerable Safety Profile
16 PHASE 1 DURABILITY Up to 7 Years of clinical benefit observed Clinical benefit and improvements observed with durable biomarker in all patients at latest trial follow-up 100% overall survival; median transplant-free survival not reached at median follow-up: 5.7 years (range: 4.3–7.1 years) Mirror
Slide 17: RP-A501 Pivotal Phase 2 Milestones
17 RP-A501 Pivotal Phase 2 Milestones TODAY Enrollment and dosing 9 additional patients in Cohort 4 MID-2027 Dosing completion Last patient dosed 12-month follow-up MID-2028 TOPLINE TARGET* Primary efficacy readout from pivotal Cohort 4 LATE-2028 BLA regulatory filing PRV eligible; Accelerated Appro
Slide 18: Estimated Epidemiology of Danon Disease is 20K+ across US & EU5
18 Schematic Male Disease Progression HTX Danon Patients HCM Symptomatic Danon Patients Pre-HCM Danon Patients Estimated Epidemiology of Danon Disease is 20K+ across US & EU5 Independent genotype and phenotype-based analyses converge on similar estimate of 10-11K US patients Genotype-Based Analysis
Slide 19: Over 900 Identified US Danon Disease Patients
19 Over 900 Identified US Danon Disease Patients Representing a current diagnosis rate under 10% CM, Cardiomyopathies; DD, Danon disease; HCM, hypertrophic cardiomyopathy; HTx, heart transplantation 1. Data as of July 2026; over 80% of patients reported in ICD-10 code and genetic testing lab data ha
Slide 20: Accelerating Danon Diagnosis: Focused Path to Launch
20 Accelerating Danon Diagnosis: Focused Path to Launch Aspiration: every person with HCM or a Danon disease signature and every at-risk relative of a confirmed Danon patient is genetically evaluated so no Danon diagnosis is missed Illustrative Diagnoses Ramp External tailwinds HCM recognition & C
Slide 21: Addressable Opportunity in Danon Extends Beyond Males with HCM
21 Addressable Opportunity in Danon Extends Beyond Males with HCM Expand the window, extend the impact, transform the disease HCM, hypertrophic cardiomyopathy; Illustrative, non-risk-adjusted peak annual commercial opportunity based on internal assumptions regarding addressable populations, diagnosi
Slide 22: New Evidence and a Defined Pivotal Path
22 New Evidence and a Defined Pivotal Path Sustained Clinical Benefit RP-A501 conferred durable disease reversal/stabilization through 36 months and up to 7 years post-RP-A501 infusion Preliminary efficacy in initial 4 patients in Phase 2 further corroborates long-term benefit identified in Phase 1
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