Realizing the Potential of Rna-Based Technology

REALIZING THE POTENTIAL OF RNA-BASED TECHNOLOGY

34TH ANNUAL COWEN AND COMPANY HEALTHCARE CONFERENCE

MARCH 4, 2014 FORWARD LOOKING STATEMENTS

This presentation includes a number of forward-looking statements, including statements about the development and clinical status of Sarepta's product candidates and the potential efficacy, safety, and clinical results from ongoing or future studies involving Sarepta’s product candidates including the potential for eteplirsen to lead to the creation of ongoing novel dystrophin and its ability to lead to significant clinical benefit, including as measured by the 6MWT and exploratory measures, over a longer course of treatment. The potential, timing and success for: obtaining clarity on a pivotal trial design; finalizing the protocol and dosing of patients with eteplirsen; regulatory meeting, submissions, filings and review and approval of Sarepta's product candidates; the potential for expedited approval by the FDA for eteplirsen; the amount and type of data that will be necessary for the FDA’s regulatory determinations; our manufacturing plans; the impact of manufacturing and development activities on NDA submission timelines; the pricing and market opportunity for our product candidates; our ability to manufacture candidates successfully; our plans to expand our research efforts and capabilities and strategic investments to grow our business and advance our product candidates; our ability to protect our intellectual property rights; future financial performance, including revenues, expenses, and financing, sufficiency of our cash reserves; funding from the government, and other sources and collaboration and partnering opportunities. STRONG MANAGEMENT TEAM WITH A TRACK RECORD OF SUCCESS ACROSS THE INDUSTRY

Cambridge, MA Chris Garabedian, CEO Headquarters and New Lab Space Sandy Mahatme, CFO

Ed Kaye, MD, CMO

Art Krieg, MD, CSO

Ty Howton, General Counsel

Jayant Aphale, SVP, Technical Operations

Shamim Ruff, VP, Regulatory and Quality

Diane Berry, VP, Gov’t Affairs & Public Policy DUCHENNE MUSCULAR DYSTROPHY DEVASTATING RARE DISEASE

SIGNIFICANT UNMET MEDICAL NEED • Small, well-defined patient pool • Strong advocacy, high-profile rare disease • Physicians, patients, parents/caregivers highly motivated to seek treatment • No disease-modifying therapies currently available, high cost of care

ATTRACTIVE MARKET OPPORTUNITY • Affects ~1 in 3500 boys worldwide • ~35,000 DMD patients in US and Europe • Lead program of exon 51 skipping drug could benefit over 4000 pts in US and EU • Additional exon-skipping drugs offer 3x-6x commercial potential beyond eteplirsen

THE CAUSE OF DUCHENNE IS A LACK OF DYSTROPHIN LESS THAN 5% OF NORMAL PROTEIN LEVELS

DMD MUSCLE TISSUE

THE DYSTROGLYCAN COMPLEX PROTECTS THE MUSCLES DURING CONTRACTION AND RELAXATION

HEALTHY MUSCLE TISSUE ETEPLIRSEN RNA MODULATOR THAT ADDRESSES THE UNDERLYING CAUSE OF DISEASE

Directs alternative splicing by skipping of exon 51 in dystrophin pre-mRNA

Systemic administration through weekly IV infusion

Charge neutral PMO chemistry

Plasma half-life of 2 to 6 hours

Cleared through the kidney

Tested up to 50 mg/kg in patients with no clinically significant treatment-related adverse events

>1,650 doses given to DMD boys to date, including more than 2 years of treatment experience EXON SKIPPING APPROACH REPAIR MRNA TO RESTORE PROTEIN TRANSLATION & DYSTROPHIN PRODUCTION

EXAMPLE OF ETEPLIRSEN AMENABLE GENOTYPE: DELETION OF EXONS 49-50 RESULTS IN AN OUT OF FRAME DELETION IN mRNA

BY SKIPPING EXON 51, IN-FRAME mRNA TRANSCRIPTION IS RESTORED, ENABLING THE PRODUCTION OF A FUNCTIONAL DYSTROPHIN PROTEIN ETEPLIRSEN PHASE IIB STUDIES STUDY 201: RAMDOMIZED, DOUBLE BLIND PLACEBO CONTROLLED STUDY 202: OPEN-LABEL, LONG-TERM SAFETY & EFFICACY

Study 201: Double-Blinded, Study 202 Placebo-Controlled Phase 2b Open –Label, Long-Term Safety an d Efficacy Study

30 mg/kg weekly

N = 4 N = 4 N = 4 50 mg/kg weekly R N = 4 N = 4 N = 4 30 mg/kg/wk Placebo * N = 2 50 mg/kg/wk N = 4 N = 2 N = 2 N = 2

* Placebo controlled group rolled over onto open-label eteplirsen 24 weeks 24 Weeks Ongoing Extension

Muscle Biopsy: Baseline Muscle Biopsy: 12 Weeks Muscle Biopsy: 24 Weeks Muscle Biopsy: 48 Weeks

SAFETY AND EFFICACY ASSESSMENTS • Safety: clinical and laboratory measures • Efficacy: primary study endpoint is biochemical measures of dystrophin, the primary clinical endpoint is the 6-Minute Walk Test

INDIVIDUAL DYSTROPHIN RESULTS BY TREATMENT GROUP OBSERVED AT 24 WEEKS WITH INCREASES THROUGH 48 WEEKS

30 mg/kg 50 mg/kg Placebo/delayed Tx 24 wks: mean=22.5% 12 wks: mean=0.8% 24 wks: mean=38.3%* 48 wks: mean=52.1%* 48 wks: mean=41.7%*

1,2 *P≤0.009 *P≤0.001 *P≤0.008 % DYSTROPHIN-POSITIVE 60% FIBERS

50% Pretreatment* 40% 12 weeks of Tx

30% 24 weeks of Tx

20% 48 weeks of Tx

10% *Pretreatment values shown for the pbo/delayed tx cohort are 0% from biopsies conducted at

Dystrophin Positive Fibers (Change From BL) From (Change Fibers Positive Dystrophin Weeks 12 or 24. Baseline values -10% Placebo, 30 mg/kg Placebo, 50 mg/kg are not shown for simplicity. Mean=34.2% Mean=42.9% Pt #2 Pretreatment 12 wks of Tx* 24 wks of Tx 48 wks of Tx Normal control

Pt 06

*The 12 week biopsy IHC image is from patient 12 in the 50mg/kg cohort. BL, baseline; PBO, placebo; Tx, treatment. 9 1. Kaye E. DMD Program Update. Muscle Study Group. Sarepta Therapeutics. September 16, 2013. 2. Mendell JR, et al. Poster presented at the Muscle Study Group (MSG) Annual Meeting.

SUPPORTIVE ANALYSES FURTHER EVIDENCE OF A ROBUST AND CONSISTENT DYSTROPHIN RESPONSE

Mean Change in Dystrophin Positive Mean Change in Dystrophin Fibers as % of Normal* Intensity per Fiber* 47.3% 37.7% 15.4% 14.3% Eteplirsen (N=8): p ≤0.001 p ≤0.009 p ≤0.001 p ≤0.006 48 wks of Tx

Placebo/Delayed-Tx (N=4): 24 wks of Tx Note: y-axis scaled for

illustrative purposes IMMUNOFLUORESCENCE * Values based on immunofluorescence using anti-dystrophin antibody MANDYS106; P-values are for comparison with baseline

All patients receiving eteplirsen IV treatment to date demonstrated a response on RT-PCR

Study N† Doses Evaluated % Response

30 mg/kg at 24 weeks and 48 weeks PCR

- Phase IIb 12 100%

50 mg/kg at 12 weeks and 48 weeks RT Phase Ib/IIa 17 0.5, 1.0, 2.0, 4.0, 10.0, and 20.0 mg/kg at 12 weeks 100%

† Enrolled patients who received muscle biopsies DYSTROPHIN DATASET PUBLISHED IN 2013 IN

ANNALS OF NEUROLOGY Western Blot (Pt 06)

Pre-Tx 48 wks Tx Healthy

RT-PCR DELETION OF

EXON 49-50 (Pt 12)

Pre- Post-

Tx Tx

Normal Control No Template

Pt Pre-Treatment 12 wks of Tx 24 wks of Tx 48 wks of Tx Normal # (50 mg/kg)* Control

Pt 06 SELECTION OF DMD PATIENTS OVER 7 YEARS OF AGE IS IMPORTANT IN ASSESSING 6MWT BENEFIT

<7 years old

>7 years old

Time in months

Mazzone et al., 24 month longitudinal data in ambulant DMD boys, PLOS ONE, 2013 PATIENT CHARACTERISTICS AT BASELINE

Cohort N Age (yrs) Weight (kg) Height (cm) BMI (kg/m2) 6 MWT (m) mean mean mean mean Mean** PBO/Delayed-Tx* 4 8.8 30.7 119.3 21.5 380.3 Eteplirsen (mITT) 6 9.4 29.4 122.2 19.5 388.6 30 mg/kg 4 9.8 34.9 130.5 20.3 347.3 50 mg/kg 4 9.1 29.1 121.3 19.6 384.8 Total 12 9.3 31.5 123.7 20.5 370.8 (Min, Max) (7.3, 11.0) (22.1, 39.8) (116, 138) (16.4, 25.6) (259, 437)

* Placebo/delayed-treatment cohort at 36 weeks had mean age of 9.5 years and mean 6MWT of 327.5 meters. ** 6MWT baseline values per patient were collected on 2 consecutive days, mean is based on average of both values. KEY INCLUSION CRITERIA • Out-of-frame deletion(s) that may be corrected by skipping exon 51 • Between the ages of 7 and 13 years • Between 200 and 400 meters (±10%) on 6MWT at Baseline • Receiving treatment with a stable dose of oral corticosteroids for at least 24 weeks before study entry 6MWT CHANGE FROM BASELINE TO WEEK 120: DATA BASED ON MAXIMUM 6MWT SCORE WHEN TEST WAS REPEATED

METERS LIKELY TIMEFRAME OF MEANINGFUL DYSTROPHIN LEVELS 20.0 -4 7 0.0 -16 -14 -14 -17 -21 -18 -20.0 -20 * -40.0 =65 m ETEPLIRSEN -60.0 TREATMENT INITIATED -69 -59 -80.0 -76 -70 -79 -79 -100.0 -88

Placebo/Delayed Tx (N=4) Eteplirsen (N=6) *p ≤ 0.006

Note: Statistical analysis based on modified Intent-To-Treat Population using MMRM Test 6MWT CHANGE FROM BASELINE TO WEEK 120: DATA BASED ON MEAN 6MWT SCORE WHEN TEST WAS REPEATED

METERS LIKELY TIMEFRAME OF MEANINGFUL DYSTROPHIN LEVELS 20.0 2 12 -4 -5 -3 0.0 -10 -7 -10 -9 -20.0 =58 m* ETEPLIRSEN -40.0 TREATMENT INITIATED -62 -63 -60.0 -55 -49 -56 -80.0 -74 -68

Placebo/Delayed Tx (N=4) Eteplirsen (N=6) *p ≤ 0.016

Note: Statistical analysis based on modified Intent-To-Treat Population using MMRM Test 6MWT NATURAL HISTORY BOYS >7 YEARS EXPERIENCE PROGRESSIVE AMBULATORY DECLINE OVER 1-2 YEARS

20 0 -20 -30 -40 -42 -43 -64 -60 -58 -80 -100 -83 -97 -120 -122 -115 -125 -140 -160 -180 Note: Natural history studies imputed zero values for patients who lost ambulation during follow up periods -190*

-200

Wk 4 Wk 8 Wk

Wk 28 Wk 96 Wk Wk 12 Wk 16 Wk 20 Wk 24 Wk 32 Wk 36 Wk 40 Wk 44 Wk 48 Wk 52 Wk 56 Wk 60 Wk 64 Wk 68 Wk 72 Wk 76 Wk 80 Wk 84 Wk 88 Wk 92 Wk

Wk 120 Wk Wk 100 Wk 104 Wk 108 Wk 112 Wk 116 Wk

Drisapersen Phase III placebo (>7yrs)* Ataluren Phase IIb placebo (>7yrs) Mazzone et al, 2013 (>7yrs) Goemans et al, 2013 McDonald et al, 2010 (>7yrs) Mercuri et al, unpublished (>7yrs; ≥350m)

* Drisapersen data from Week 48 to 96 is from extension study DMD114349, and also includes placebo-treated patients >7 years from the Phase II DMD114117 study who enrolled in this extension study. Over this time period in the extension study, patients received open-label drisapersen treatment. ETEPLIRSEN VERSUS 6MWT NATURAL HISTORY MEAN CHANGE FROM BASELINE THROUGH 120 WEEKS

ETEPLIRSEN mITT COHORT 20 BASELINE TO WK 120 0 -10 -20 PBO/DEL-TX COHORT -40 BASELINE TO WK 120 -60 -68 -80 PBO/DEL-TX COHORT -100 INITIATED ETEPLIRSEN TREATMENT AT WK 24 -120 -140 -160 -180 Note: Natural history studies imputed zero values for patients who lost ambulation during follow up periods

-200

Wk 4 Wk 8 Wk

Wk 28 Wk 96 Wk Wk 12 Wk 16 Wk 20 Wk 24 Wk 32 Wk 36 Wk 40 Wk 44 Wk 48 Wk 52 Wk 56 Wk 60 Wk 64 Wk 68 Wk 72 Wk 76 Wk 80 Wk 84 Wk 88 Wk 92 Wk

Wk 120 Wk Wk 100 Wk 104 Wk 108 Wk 112 Wk 116 Wk

Drisapersen Phase III placebo (>7yrs)* Ataluren Phase IIb placebo (>7yrs) Mazzone et al, 2013 (>7yrs) Goemans et al, 2013 McDonald et al, 2010 (>7yrs) Mercuri et al, unpublished (>7yrs; ≥350m)

ETEPLIRSEN mITT COHORT 20 WK 12 TO WK 120 (DYSTROPHIN CONFIRMED AT WK 24) 0 -13 -20 -13 -40 PBO/DEL-TX COHORT WK 36 TO WK 120 -60 (DYSTROPHIN CONFIRMED AT WK 48) -80 -100 -120 -140 -160 -180 Note: Natural history studies imputed zero values for patients who lost ambulation during follow up periods

-200

Wk 4 Wk 8 Wk

Wk 28 Wk 96 Wk Wk 12 Wk 16 Wk 20 Wk 24 Wk 32 Wk 36 Wk 40 Wk 44 Wk 48 Wk 52 Wk 56 Wk 60 Wk 64 Wk 68 Wk 72 Wk 76 Wk 80 Wk 84 Wk 88 Wk 92 Wk

Wk 120 Wk Wk 100 Wk 104 Wk 108 Wk 112 Wk 116 Wk

Drisapersen Phase III placebo (>7yrs)* Ataluren Phase IIb placebo (>7yrs) Mazzone et al, 2013 (>7yrs) Goemans et al, 2013 McDonald et al, 2010 (>7yrs) Mercuri et al, unpublished (>7yrs; ≥350m)

* Drisapersen data from Week 48 to 96 is from extension study DMD114349, and also includes placebo-treated patients >7 years from the Phase II DMD114117 study who enrolled in this extension study. Over this time period in the extension study, patients received open-label drisapersen treatment. 6MWT DISTANCE: PERCENT CHANGE FROM BASELINE AT WEEK 120 INDIVIDUAL PATIENT DATA

% Change in % Change in 6MWT Distance (m) % Change in Age at 6MWT FROM WK 36 THROUGH WK Ambulatory Age at 6MWT Distance (m) <10% 120 Patients Baseline Distance (m) At 120 120 change at 36 wks wks (from last timepoint before dystrophin wks confirmed in placebo patients) 10-15% decline ETEPLIRSEN 9.03 -4.5 11.34 -12.9 -8.8 >15% ETEPLIRSEN 10.53 -10.8 12.84 +0.5 +12.7 decline ETEPLIRSEN * 7.29 +14.2 9.60 -0.2 -12.7 ETEPLIRSEN 8.79 -7.5 11.10 -2.8 +5.0 ETEPLIRSEN ** 10.95 -14.5 13.26 -18.9 -5.1

ETEPLIRSEN 9.60 -4.2 11.91 +10.0 +14.8

PBO/Delayed Tx 7.56 -15.4 9.87 -4.3 +13.1

PBO/Delayed Tx † 10.03 -17.0 12.34 -29.1 -14.6

PBO/Delayed Tx 7.55 -16.2 9.86 -24.5 -9.8 PBO/Delayed Tx 10.12 -18.9 12.43 -19.5 -0.8

Average Age at 120 Weeks: Eteplirsen = 11.7 yrs; Placebo/Delayed Tx = 11.1 yrs

* Youngest patient in Study; ** Oldest patient in Study; † Patient recovering from broken left ankle and was unable to perform test at Week 84 Percentages based on maximum value (predefined primary analysis) of two measures taken at baseline NATURAL HISTORY DATA SHOW BASELINE 6MWT OF <330-350 METERS IS PREDICTIVE OF LOSS OF AMBULATION OVER 84 WEEKS*

450

404 400 400 = -4 m n=5

350 317 n=4 (wk 84 only) 315

METERS = -2 m 300 n=5

250

200 Wk 36 Wk 48 Wk 62 Wk 74 Wk 84 Wk 96 Wk 120

>350 <350

Note: Mean age: 9.9 years at week 36; 11.5 years at week 120 Includes Modified Intent-to-Treat (mITT) population *Goemans et al, 2013 PULMONARY FUNCTION TESTS PHASE IIB EXPLORATORY EFFICACY ENDPOINTS

RESPIRATORY FUNCTION DECLINE IN DMD

High incidence of respiratory illness and death in late-stage DMD patients associated with progressive muscle weakness

Majority of respiratory failures due to ineffective cough and impaired airway clearance

MAXIMUM INSPIRATORY AND EXPIRATORY PRESSURE (MIP AND MEP) AND FORCED VITAL CAPACITY (FVC)

Sensitive measures of respiratory muscle strength well characterized in the disease natural history

MEP typically deteriorates before MIP and FVC in DMD patients

Declines in MIP and MEP correlate with decreases in voluntary cough capacity

Braverman et al; Smith et al, 1987; Galasko et al, 1992; Hahn et al, 1997; Kang et al, 2000 SUMMARY OF PULMONARY FUNCTION TESTS: WEEK 120 TREATMENT RESULTS

Mean Baseline PFT Pulmonary Function Test (PFT)† Value Mean Week 120 Value % Change from Baseline*

Maximum Inspiratory Pressure 63.1 cm H2O 72.3 cm H2O 14.6%

Maximum Expiratory Pressure 68.1 cm H2O 78.3 cm H2O 15.0%

Forced Vital Capacity 1.73 liters 1.88 liters 8.7%

Forced Vital Capacity % Predicted 101.3% 93.2% -8.0%

Maximum Inspiratory Pressure % Predicted 90.2% 95.2% 5.5%

Maximum Expiratory Pressure % Predicted 79.3% 79.6% 0.4%

DMD, Duchenne muscular dystrophy; FVC, forced vital capacity; MEP, maximum expiratory pressure; MIP, maximum inspiratory pressure. 1. Smith PE, et al. N Engl J Med. 1987;316(19):1197-1205. 2. Braverman JM. Airway Clearance Needs in Duchenne's Muscular Dystrophy: 22 An Overview. Hill-Rom. 3. Hahn A, et al. Arch Phys Med Rehabil. 1997;78(1):1-6.

MIP AND MEP NATURAL HISTORY PROGRESSIVE DECLINE BEGINS IN PATIENTS AS YOUNG AS 5 TO 10 YEARS OLD

MIP PERCENT PREDICTED MEP PERCENT PREDICTED cm H2O (% predicted) cm H2O (% predicted) 100 50 90 45 80 KIRHANI, 2013 (N=48) 40 CINRG, 2013 (N=340) 70 35 60 30 50 25 40 20 30 15 KIRHANI, 2013 (N=48) 20 Note: CINRG used a different 10 10 equation resulting in lower values CINRG, 2013 (N=340) 5 0 0 8 9 10 11 12 13 14 15 16 17 18 19 8 9 10 11 12 13 14 15 16 17 18 19 Age Age

MCDONALD, 1995 MCDONALD, 1995 (N=26) (N=26) MEP & MIP % PREDICTED TO WEEK 120 INTENT-TO-TREAT POPULATION % 150 MEP (N=12) MIP (N=12) 125 100 90 90 92 95 82 84 84 87 84 84

75 79 81 80 76 78 77 78 72 72 75 50 25 0

“Decreased maximal static airway pressures (MIP and MEP) were the earliest changes observed in our DMD subjects between 5 and 10 years of age” (Craig McDonald Am J Phys Med Rehabil. 1995)

24 Preliminary Analysis SAFETY THROUGH 120 WEEKS

ETEPLIRSEN ETEPLIRSEN PLACEBO TREATMENT- • No clinically significant treatment-related FOR FOR FOR EMERGENT adverse events 96 WKS 120 WKS 24 WKS ADVERSE EVENT N=4 (%) N=8 (%) N=4 (%) • One treatment-unrelated serious adverse Procedural pain 1 (25) 6 (75) 3 (75) Vomiting 2 (50) 4 (50) 0 event (distal femur fracture), and no Hypokalaemia 0 4 (50) 2 (50) hospitalization or discontinuations Cough 1 (25) 4 (50) 2 (50) Back pain 0 4 (50) 2 (50) • No clinically significant treatment-related Fall 0 2 (25) 1 (25) changes detected on any safety laboratory Headache 4 (100) 3 (38) 2 (50) parameters including liver-specific enzymes, Balance disorder 0 3 (38) 0 Diarrhoea 1 (25) 2 (25) 1 (25) kidney function, coagulation profiles or Dermatitis Contact 0 3 (38) 0 platelet counts Pyrexia 0 2 (25) 2 (50) Haematoma 0 2 (25) 1 (25) • Reported cases of transient urine protein Abdominal pain 2 (50) 0 2 (50) elevations resolved without intervention and Nausea 2 (50) 1 (12) 1 (25) Rhinitis 0 1 (12) 1 (25) resulted in no clinical symptoms and no Polyuria 0 1 (12) 0 other laboratory kidney marker changes Muscle Spasms 2 (50) 1 (12) 0 Musculoskeletal Pain 0 1 (12) 0 Proteinuria 0 2 (25) 1 (25) Injection Site Pain 0 1 (12) 0 TREATMENT-RELATED ADVERSE EVENTS, SERIOUS ADVERSE EVENTS AND ADVERSE EVENTS OF SPECIAL INTEREST

Placebo Through Eteplirsen for 30 mg/kg 50 mg/kg Patients with 24 weeks 96 weeks For 120 weeks For 120 weeks N=4 (%) N=4 (%) N=4 (%) N=4 (%) Treatment-Related AE 1 (25) 0 1 (25) 2 (50)

Serious Adverse Event 0 0 1 (25)* 0 AEs Leading to Treatment 0 0 0 0 Interruption

AEs Leading To Discontinuation 0 0 0 0 Any AE of Special Interest

Injection Site Pain† 0 0 0 1 (25) Renal Toxicity (Proteinuria) 1 (25)** 0 1 (25)** 1 (25)** Inflammation 0 0 0 0 Coagulation 0 0 0 0 Hepatic Toxicity 0 0 0 0 Thrombocytopenia †† 0 0 0 0

* Treatment-unrelated fracture of distal femur ** Transient positive reading via dipstick that resolved without intervention or treatment interruption † No reported incidents of erythema, induration or discoloration at injection sites †† Thrombocytopenia was defined as a platelet count below 100,000 per µL SAREPTA IS COMMITTED TO IMPROVING THE LIVES OF PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY

Best-in-class breakthrough technology: Industry-leading RNA technology platform

Disease-modifying approach: Targeting the underlying cause of Duchenne muscular dystrophy as foundational treatment for patients

Commitment to patients: Dedicated to bringing our exon-skipping technology to all patients who may benefit

Sarepta Therapeutics. http://www.sareptatherapeutics.com. 27 PRIVILEGED AND CONFIDENTIAL, NOT FOR DISTRIBUTION

BEYOND EXON 51: OTHER GENETIC SUBTYPES ADAPTABLE PMO CHEMISTRY ~80% OF PATIENTS HAVE A GENOTYPE THAT MAY BE ADDRESSED BY EXON SKIPPING

25,000

20,000

15,000

10,000

5,000

Estimated Number Number of US/EU Patients Estimated 0 51 45 53 44 46 52 50 43 8 55 2 17 7 12 23 18 20 21 19 22

Top 20 Single Exons To Be Skipped

EU, European Union; PMO, phosphorodiamidate morpholino oligomer; US, United States. 1. Aartsma-Rus A, et al. Hum Mutat. 2009;30:293-299. 2. Kaye E. DMD Program Update. Muscle Study Group. Sarepta Therapeutics. 29 September 16, 2013.

UWA COLLABORATION SUPPORTS FURTHER EXPANSION OF EXON-SKIPPING PIPELINE

30 SAREPTA’S EXON SKIPPING PLATFORM FOR DMD LEAD CANDIDATES RAPIDLY PROGRESSING TO CLINIC

TARGET DISCOVERY PRECLINICAL CLINICAL STATUS ETEPLIRSEN • 120-week data reported (EXON 51) • Ongoing FDA discussions on regulatory path • Pre-IND meeting completed EXON 45 • IND-enabling preclinical studies underway • Pre-IND meeting scheduled in Q1 EXON 53 • IND-enabling preclinical studies underway

EXON 50 • Lead sequence identified

EXON 44 • Lead sequence selection underway

EXON 52 • Lead sequence selection underway

EXON 55 • Lead sequence selection underway

EXON 8 • Lead sequence selection underway 2014 CORPORATE MILESTONES ONGOING DISCUSSIONS WITH FDA TO DETERMINE ETEPLIRSEN REGULATORY PATH

TIMING ANTICIPATED MILESTONE

1ST QTR 120-week eteplirsen data

1ST QTR Follow up meeting with FDA tentatively scheduled for March

2ND QTR Sequence selections for exons 52, 55 and 8

2ND QTR Final confirmatory eteplirsen study protocol submitted to FDA and key IRBs

2ND HALF First patient dosed in Phase I/II study of SRP-4053

2ND HALF 144-week eteplirsen data

2ND HALF 2 or more INDs submitted to FDA for follow-on exon candidates

2ND HALF R&D update on new early-stage research program beyond DMD THE POWER OF RNA THERAPEUTICS UPSTREAM ACTIVITY VERSUS TRADITIONAL SMALL MOLECULES AND BIOLOGICS

Ribosome Protein is RNA Pre-mRNA mRNA leaves the translates mRNA transported to transcription spliced into nucleus and assembles perform its begins mature mRNA the protein function PHOSPHORODIAMIDATE MORPHOLINO OLIGOMER (PMO) CORE BACKBONE CHEMISTRY IS DIFFERENTIATED FROM OTHER RNA TECHNOLOGIES

SPECIFICITY • Charge neutral • Few off-target effects

STABILITY • Wide therapeutic window • Resistant to enzymatic degradation

VERSATILITY • Modular construct allows rapid design • Target any human or pathogen RNA COMPARISON OF PMO TO PHOSPHOROTHIOATE

PMO Phosphorothioate

R = MOE

Eteplirsen R (Mipomersen)

OMe (Drisapersen)

R RNA (siRNA)

R EFFICIENCY OF PMO VERSUS 2-O’-METHYL PUBLISHED PRECLINICAL COMPARISON IN DMD MOUSE MODEL

Gastrocnemius Quadriceps Triceps WILD TYPE MUSCLE Mdx 2-O’-METHYL PMO 2-O’-METHYL PMO 2-O’-METHYL PMO SHORT LONG SHORT LONG SHORT LONG

10% 1% 0.1% 0% 1% 0.5% 10% 4% 2.5% 14% 2% 1.5% 14%

Tibialis anterior Heart Diaphragm WILD TYPE MUSCLE Mdx 2-O’-METHYL PMO 2-O’-METHYL PMO 2-O’-METHYL PMO SHORT LONG SHORT LONG SHORT LONG

20% 2% 0.2% 0% 3% 2.5% 30% 2% 0.1% 0.6% 2% 2% 18%

PMO significantly more active than 2-O’-methyl phosphorothioate at producing dystrophin protein at ~100 mg/kg* dose using the same sequence

* 14.52 μmol/kg Heemskerk et al, 2009 PMO DEMONSTRATES HIGHER EXON-23-SKIPPING ACTIVITY VERSUS 2-’O-METHYL IN DMD MOUSE MODEL

Heemskerk HA, et al. J Gene Med. 2009;11(3):257-266. DIFFERENTIATED CHEMISTRY AND SEQUENCE POTENCY FOR ETEPLIRSEN

SEQUENCE-SPECIFIC POTENCY1 (Human myoblasts)

ETEPLIRSEN

PRO051 SEQ (PMO)

EXON 51 SKIPPING EXON (%) EXON 51 SKIPPING EXON (%)

ETEPLIRSEN (PMO) PRO051 SEQUENCE (PMO) PMO CONCENTRATION (μM) CHEMISTRY-SPECIFIC CYTOKINE INDUCTION (Human B-Cells)

IL10 IL6 RANTES TNF

24 48 72 24 48 72 24 48 72 24 48 72 HOURS PRO051 SEQ (2OMe)

PRO051 SEQ (PMO) LOG2 CYTOKINE INDUCTION AVI-4657 (PMO) LOWEST HIGHEST

CLASS B CpG

2OMePS, 2’-O-METHYL PHOSPHOROTHIOATE; IL, interleukin; PMO, phosphorodiamidate morpholino oligomer; TMF, tumor necrosis factor. 38 1. Data on file. Sarepta Therapeutics, Cambridge, MA. PMO VERSUS 2-O’-METHYL SUMMARY

Leiden researchers showed that PMO chemistry has up to 10-fold higher dystrophin production in DMD mouse model across various muscle groups

Sarepta comparison studies of eteplirsen versus PRO051 sequences showed up to 10-fold higher exon-skipping activity controlling for all other variables

Sarepta’s eteplirsen studied at a 5- to 8- fold higher dose than drisapersen in clinical studies (30mg-50mg/kg vs. 6mg/kg) for DMD

Cytokine screen demonstrated clear differentiation between PMO and 2-O’-Methyl chemistries with respect to induction of inflammatory markers NEXT GENERATION PMO-BASED CHEMISTRIES ENHANCED TISSUE TARGETING, INTRACELLULAR DELIVERY AND DRUG POTENCY

NEXT GENERATION PMO CHEMISTRIES

PMO-X™ PMOplus™ PPMO Incorporates proprietary technology to Adds positionally-specific molecular Attaches peptide conjugates fine-tune physicochemical properties charges

A UNIVERSE OF POSSIBILITIES WITH PMO-BASED RNA MODULATION R&D FOCUSED ON HIGH-VALUE TARGETS PIPELINE SUMMARY

CLINICAL PROGRAMS DISCOVERY PRE-CLINICAL PHASE 1 PHASE 2 PHASE 3

Eteplirsen (AVI-4658) DMD (Exon 51)

SRP-4053 DMD (Exon 53)

SRP-4045 DMD (Exon 45)

SRP-4050 DMD (Exon 50)

SRP-4044 DMD (Exon 44) Rare

Diseases SRP-4052 DMD (Exon 52)

SRP-4055 DMD (Exon 55)

SRP-4008 DMD (Exon 8)

Undisclosed targets Non-DMD

AVI-7288 Marburg Virus

AVI-7537 Ebola Virus

s AVI-7100 Influenza

Viral PMO-X Dengue

Disease Infectious Bacterial PPMO TB Undisclosed targets FINANCIAL OVERVIEW

Shares Outstanding ~37.8 million

Recent Closing Price $28.36 per share (03/03/14)

~1.9mm shares daily Trading Volume (90 day average volume)

Market Capitalization ~$1.1 billion

Cash & Other Investments (Unaudited) ~$265 million as of 12/31/13 SAREPTA’S FUTURE IS BRIGHT LONG-TERM VALUE DRIVERS

Compelling clinical proof-of-concept in DMD

Differentiated RNA-based technologies

Promising early-stage R&D and a growing pipeline