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1 March 2019 Important InformationCautionaryStatementRegardingF orward-LookingStatementsVariousstatement sinthisreleaseconcerningRocket sfutureexpectations,plansandprospects,in cludingwithoutlimitation,Rocket sexpectationsregardingthesafety,effectiv enessandtimingofproductcandidatesthatRoc ketmaydevelop,includingincollaborationwi thacademicpartners,totreatFanconiAnemia( FA),LeukocyteAdhesionDeficiency-I(LAD-I) ,PyruvateKinaseDeficiency(PKD)andInfanti leMalignantOsteopetrosis(IMO),andthesafe ty,effectivenessandtimingofrelatedpre-cl inicalstudiesandclinicaltrials,mayconsti tuteforward-lookingstatementsforthepurpo sesofthesafeharborprovisionsunderthePriv ateSecuritiesLitigationReformActof1995an dotherfederalsecuritieslawsandaresubject tosubstantialrisks,uncertaintiesandassum ptions.

2 Youshouldnotplacerelianceontheseforward- lookingstatements,whichoftenincludewords suchas"believe","expect","anticipate","i ntend","plan","willgive","estimate","see k","will","may","suggest"orsimilarterms, variationsofsuchtermsorthenegativeofthos eterms. AlthoughRocketbelievesthattheexpectation sreflectedintheforward-lookingstatements arereasonable,Rocketcannotguaranteesucho utcomes. Actualresultsmaydiffermateriallyfromthos eindicatedbytheseforward-lookingstatemen tsasa resultofvariousimportantfactors,includin g,withoutlimitation,Rocket sabilitytosuccessfullydemonstratetheeffi cacyandsafetyofsuchproductsandpre-clinic alstudiesandclinicaltrials,itsgenetherap yprograms,thepreclinicalandclinicalresul tsforitsproductcandidates,whichmaynotsup portfurtherdevelopmentandmarketingapprov al,Rocket sabilitytocommencea registrationalstudyinFAwithintheprojecte dtimeperiods,thepotentialadvantagesofRoc ket sproductcandidates,actionsofregulatoryag encies,whichmayaffecttheinitiation,timin gandprogressofpre-clinicalstudiesandclin icaltrialsofitsproductcandidates,Rocket sanditslicensorsabilitytoobtain.

3 Maintainandprotectitsandtheirrespectivei ntellectualproperty,thetiming,costorothe raspectsofapotentialcommerciallaunchofRo cket sproductcandidates,Rocket sabilitytomanageoperatingexpenses,Rocket sabilitytoobtainadditionalfundingtosuppo rtitsbusinessactivitiesandestablishandma intainstrategicbusinessalliancesandnewbu sinessinitiatives,Rocket sdependenceonthirdpartiesfordevelopment, manufacture,marketing,salesanddistributi onofproductcandidates,theoutcomeoflitiga tion,andunexpectedexpenditures,aswellast hoserisksmorefullydiscussedinthesectione ntitled RiskFactors inRocket sAnnualReportonForm10-K fortheyearendedDecember31, , ,andRocketundertakesnoobligationtoupdate orrevisepubliclyanyforward-lookingstatem ents,whetherasa resultofnewinformation, Therapy: Why Now?

4 In Vivo (In Body)AAV Gene TherapyEx Vivo (Outside Body)Lentiviral Gene TherapyRemove cells &isolate patient HSCsLaboratory-produced LVLaboratory-produced AAVD irect intravenous injectionGene-modifyHSCsInfusion of modified HSCsTherapeuticLV VTherapeuticAAV4 About Rocket PharmaMulti-Platform Gene Therapy (GTx) Company Targeting Rare Diseases1st-in-classwith direct on-target mechanism of action (MOA) and clear clinical endpointsEx-vivo Lentiviral vectors (LVV) Fanconi Anemia (FA) Leukocyte Adhesion Deficiency-I (LAD-I) Pyruvate Kinase Deficiency (PKD) Infantile Malignant Osteopetrosis(IMO)In-vivo adeno-associated virus (AAV) Danon Disease Multiple Near- & Medium-term Company Value DriversNear-term Milestones (2019) Four programs in the clinic (FA, LAD-I, PKD, Danon) Additional clinical data for FA (Next 12-18 months) FA and LAD-I advance to potential registration trial stage Medium-term Milestones (2020-2021) Ongoing registration trials for currently planned programs.

5 First BLA submission Platform establishment and pipeline expansion Currently planned programs eligible for Pediatric Priority Review Vouchers Strong Precedents and World-Class ExpertiseStrong Precedents and Sound Strategy Precedents for LVV- & AAV-based therapies Clearly-defined product metrics across indications Experienced company leadership Leading research and manufacturing partners5 Gaurav Shah, Chief Executive OfficerJonathan Schwartz, & SVP, Clinical DevelopmentKinnari Patel, , MBACOO & EVP, DevelopmentAnnahita Keravala, , AAV PlatformGayatri R. Rao, , , Reg Policy & Patient AdvocacyRaj Prabhakar, MBASVP, Bus Operations & Bus DevelopmentClaudineProwse, , Strategy & Corporate DevChristopher Ballas, , ManufacturingBrian C.

6 Beard, , CMCL enti& AAVL eadership Team: Expertise in GTx & Rare Diseases Clinical DevelopmentSpearheaded Kymriah (CART-19) development at Novartis towards approvalLed multiple biologics approvalsLed Opdivoand six rare disease indication approvals~20 years cell and gene therapy development & manufacturing7-Year Former Director of FDA s Office of Orphan Products Development ~17 years cell, gene and biotech business development ~20 years capital markets, strategy, corporate development20+ years gene therapy expertise15+ years cell and gene therapies expertise6 DiscoveryPreclinicalPhase 1 Phase 2 DesignationsFast Track, Orphan Drug ( )RMAT, ATMP, Fast Track, Rare Pediatric, Orphan Drug ( )ATMP, Fast Track, Rare Pediatric, Orphan Drug ( )Orphan Drug ( )

7 Orphan Drug ( )Rocket s Expanding Pipeline: Potential for Significant Value Creation Near and Long TermRP-A501 Danon DiseaseRP-L102 Fanconi AnemiaRP-L201 Leukocyte Adhesion Deficiency-IRP-L301 Pyruvate Kinase DeficiencyRP-L401 Infantile Malignant OsteopetrosisAAVLV VProcess B in the & Process A in the **Phase 1/27RP-L201 Leukocyte Adhesion Deficiency-IRP-A501 Danon DiseaseRP-L102 Fanconi AnemiaRP-L301 Pyruvate Kinase DeficiencyRP-L401 Infantile Malignant OsteopetrosisDanon Disease Monogenic Heart Failure SyndromeOverview: Background: Devastating multisystemic disorder caused by highly penetrant and X-linked dominant LAMP2mutations Currently available treatments: Non-curative heart transplants associated with considerable morbidity and mortality Addressable Market: Estimated US+EU prevalence of 15,000-30,000 RP-A501: AAV9 gene therapy that elicits improvements in survival, cardiac function, and liver enzymes in preclinical studies Regulatory Designations: Orphan Drug & Fast Track designations in the US8 Danon Disease: An Impairment in Autophagy Caused by LAMP2B Mutations9P< < < < **PBS = Phosphate Buffered Saline (Negative Control) Lower dP/dt max indicates impaired contractility.

8 Higher (less negative) dP/dt min indicates impaired heart relaxationRP-A501 Restores Cardiac Function in KO Mice Dose-Dependent Improvements in Systolic and Diastolic Function in LAMP2 KO Mice10RP-A501 Shows Survival Benefit at Higher DosesNote: All mice were sacrificed at Month 1011 RNA: RP-A501 Elicits Expression of hLAMP2B mRNA in Cardiac Tissue of KO Mice*hLAMP2B = Human LAMP2 BhLAMP2B mRNA*12 Protein: RP-A501 Elicits Durable Expression of LAMP2B Protein and Autophagic Flux in HeartLAMP2 Protein ExpressionData are Mean SEM. N=5-8 per group. Untx= Untreated, PBS = Phosphate buffered saline*Mouse LAMP2 and Human LAMP2 data are from separate Western blots. LC3-II Protein ExpressionWestern Blot13 Structural: RP-A501 Reduces Autophagic Vacuoles in All Examined OrgansWild TypeKO Control5e13 vg/kg1e14 vg/kg2e14 KOHeartLiverSkeletalMuscle14 Dose-dependent Widespread LAMP2 Expression in Cardiac Tissue1415 RP-A501 Shows Phenotype Improvements:-Survival benefit at higher doses-Dose-dependent restoration of cardiac function-Improvement in liver enzymes RP-A501 Reduces Autophagic Vacuoles in All Examined Organs: Heart, Liver, Skeletal Muscle RP-A501 Elicits dose-dependent increase in LAMP2 mRNA and proteinPreclinical Efficacy Summary16 RP-A501 Preclinical Safety Profile.

9 -No therapy-related deaths-No significant hematologic changes-No significant biochemical changes-No significant clinical chemistry changes-Mild and transient ALT elevation that self-resolvedNo Toxicities Observed in Mouse and Monkey Models17RP-A501 Clinical Development PlansAdaptive Study( )Confirmatory StudyNatural History Study/Registry (3 year, ~200 patients)Phase 1 Phase 2 / Registrational Study for Accelerated/Conditional Approval2019 20202019 Phase 1 with clinical GMP AAV9 RP-A501 in patients with Danon disease Continue registry & patient education/identification Clinical retrospective database in progress2020 Phase 2/Registrational Study for BLA/MAA submission seeking Accelerated ApprovalNatural History Identifier: NCT0376638618 Danon Disease Prevalence: ~15-30K in the US+EUUS+EU Prevalence: ~15-30,000 Hypertrophic Cardiomyopathy (HCM) US HCM Prevalence.

10 600K-1MM+1 1-4% of HCM patients consistently identified with LAMP2mutations in multiple studies with >1000 subjects evaluated2 Danon Disease Patients with HCM3o85% of males o30% of femalesDilated Cardiomyopathy (DCM) Danon Disease Patients with DCM3o15% of maleso50% of femalesHypertrophic CardiomyopathyDilated CardiomyopathyOther1 Source: J Am Coll Cardiol. 2015 Mar 31;65(12):1249-1254. 2 Sources: Heart. 2004 Aug;90(8):842-6. N Engl J Med. 2005 Jan 27;352(4):362-72. Genet Med. 2015 Nov;17(11):880-8. Gene. 2016 Feb 15;577(2):227-35. J Cardiovasc Transl Res. 2017 Feb;10(1):35-46 3 Sources: Neurology. 2002 Jun 25;58(12):1773-8. Genet Med. 2011 Jun;13(6):563-8. Rev Esp Cardiol (Engl Ed). 2018 Aug a rAgenHCMn Danon% mutations in 197 HCM patients at a general hospital in ParisArad storage diseases in 75 consecutive pts diagnosed with HCM (multicenter US/EU).