RESULTS AT 48 WEEKS OF A PHASE IIB EXTENSION STUDY OF THE EXON-SKIPPING DRUG ETEPLIRSEN IN PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY (DMD) JR MENDELL, L RODINO-KLAPAC, Z SAHENK, K ROUSH, L BIRD, LP LOWES, L ALFANO, AM GOMEZ, S LEWIS, V MALIK, K SHONTZ, KM FLANIGAN, JR KEAN, HD ALLEN, C SHILLING, COLUMBUS, OH P SAZANI, EM KAYE, CAMBRIDGE, MA
WORLD MUSCLE SOCIETY CONGRESS 2012 PERTH, AUSTRALIA OCTOBER 13, 2012
DUCHENNE MUSCULAR DYSTROPHY (DMD): GENETIC DELETIONS DISRUPT THE DYSTROPHIN READING FRAME AND PREVENT PROTEIN TRANSLATION
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 exon skipping
•
Systemic administration through weekly IV infusion
•
PMO: Charge neutral
•
Plasma half-life of 2 to 6 hours
•
Cleared through the kidney
•
Tested up to 50 mg/kg in patients with no treatment related adverse events
EXON-SKIPPING APPROACH: REPAIR mRNA TO RESTORE PROTEIN TRANSLATION AND 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 DYSTORPHIN PROTEIN
STUDY 202: ETEPLIRSEN PHASE IIB EXTENSION STUDY OPEN-LABEL, LONG-TERM SAFETY & EFFICACY
LONG-TERM SAFETY AND EFFICACY ASSESSED •
• •
Biochemical measures of dystrophin: % dystrophin positive-fibers is primary study endpoint 6-Minute Walk Test is primary clinical outcome measure Safety: clinical and laboratory measures
*Patients who were originally on placebo crossed over to treatment at 24 weeks, and are referred to as the delayed-treatment group
PATIENT CHARACTERISTICS AT BASELINE Cohort
N
Age (yrs)
Weight (kg)
Height (cm)
BMI (kg/m2)
6 MWT (m)
mean
mean
mean
mean
Mean*
Placebo
4
8.5
31
119
21
395
30 mg/kg
4
9.3
35
130
20
355
50 mg/kg
4
8.5
29
121
20
396
Total (Min, Max)
12
8.8 (7, 10)
32 (22, 40)
124 (116, 138)
20 (16, 26)
382 (261, 456)
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 baseline values per patient were collected on 2 consecutive days, mean is based on highest score per patient.
DYSTROPHIN QUANTIFICATION METHODOLOGY DYSTROPHIN-POSITIVE FIBERS AS A PERCENT OF NORMAL • Well controlled blinded methodology provides reliability and statistical power – Surgical biopsy taken from alternating biceps muscles pre- and post-treatment – Samples based on two blocks of muscle tissue, 24 section slides, more than 1000 fiber counts per patient per biopsy visit – Slides are processed for immunofluorescent detection of dystrophin (antibody MANDYS106) and counted as either positive or negative for dystrophin – Mean values of dystrophin positive fibers (divided by total fibers counted) calculated across all samples – Pre-treatment mean values of dystrophin (revertant fibers and background dystrophin levels) subtracted from post-treatment mean values to arrive at % of dystrophin positive fibers that resulted from eterplirsen treatment – Results expressed as percentage of normal positive controls (100% positive fibers)
DYSTROPHIN RESULTS IN ETEPLIRSEN-TREATED PATIENTS IN ALL DOSE GROUPS THROUGH WEEK 48* MEAN CHAGE FROM BASELINE IN % DYSTROPHIN POSTIVE FIBERS
P-VALUE
47.0
≤0.001
Eteplirsen 50mg/kg (n=4)
41.7
≤0.008
Eteplirsen 30mg/kg (n=4)
52.1
≤0.001
Placebo/Delayed Tx: 24 wks of Tx (n=4)
38.3
≤0.009
Placebo/50mg/kg Delayed-Tx (n=2)
42.9
ns
Placebo/30mg/kg Delayed-Tx (n=2)
34.2
ns
TREATMENT ARM
Eteplirsen: 48 wks of Tx (n=8)
* Values based on Immunofluorescence using anti-dystrophin antibody MANDYS106
DYSTROPHIN PRODUCTION FROM ETEPLIRSEN TREATMENT: OBSERVED AT 24 WEEKS WITH INCREASES THROUGH 48 WEEKS
Dystrophin Positive Fibers (change from baseline)
30 mg/kg 24 wks: Mean = 22.5% 48 wks: Mean = 52.1%* * p ≤0.001
50 mg/kg 12 wks: Mean = 0.8% 48 wks: Mean = 41.7%* * p ≤0.008
Placebo/Delayed Tx 24 wks: Mean = 38.3%* *p ≤0.009
60% 50% 40% 30% 20% 10% 0% -10% Placebo, 30 mg/kg Placebo, 50 mg/kg Mean = 34.2% Mean = 42.9%
Duration of Eteplirsen Treatment: No Tx
12 wks of Tx
24 wks of Tx
48 wks of Tx
* Values based on Immunofluorescence using anti-dystrophin antibody MANDYS106
DYSTROPHIN POSITIVE FIBERS CORRECTLY LOCALIZED AT THE SARCOLEMA 30 MG/KG Patient 02
09
06
10
Pre-Tx
24 wks of Tx
48 wks of Tx
DYSTROPHIN POSITIVE FIBERS CORRECTLY LOCALIZED AT THE SARCOLEMA 50 MG/KG Patient
03
04
12
15
Pre-Tx
PLACEBO/DELAYED TX 48 wks of Tx
Patient 05 (50 mg/kg)
13 (50 mg/kg)
08 (30 mg/kg)
07 (30 mg/kg)
Pre-Tx
24 wks of Tx
WESTERN BLOT AND RT-PCR CONFIRM PRODUCTION OF NOVEL DYSTROPHIN FROM EXON 51 SKIPPING
Pt 08: Pbo/ Delayed Tx, 30 mg/kg
Pt 12: 50 mg/kg
RT-PCR DELETION OF EXON 49-50 (Pt 12)
Pt 10: 30 mg/kg
Pre-Tx
Post-Tx
Mandys106
Actin
Skipped Product
Results are representative of all study subjects
Normal Control No Template
Normal Control
WESTERN BLOT
6MWT CHANGE FROM BASELINE TO WEEK 48: INTENT-TO-TREAT POPULATION: ETEPLIRSEN 50MG/KG VS PLACEBO METERS 21
20.0 -3
0.0
-6
-12
-20.0 -29
= 89 m***
-40.0 ETEPLIRSEN TREATMENT INITIATED
-60.0
-63
-80.0
-68 -78
***
Placebo/Delayed Tx (N=4)
Eteplirsen 50 mg/kg (N=4)
Note: Statistical analysis based on Intent-To-Treat Population using ANCOVA test
p ≤0.016
6MWT CHANGE FROM BASELINE TO WEEK 48: INTENT-TO-TREAT POPULATION: ETEPLIRSEN 50MG/KG VS PLACEBO METERS
LIKELY TIMEFRAME OF MEANINGFUL DYSTROPHIN LEVELS
21
20.0 -3
0.0
-6
-12
-20.0 -29
= 89 m***
-40.0 ETEPLIRSEN TREATMENT INITIATED
-60.0
-63
-80.0
-68 -78
***
Placebo/Delayed Tx (N=4)
Eteplirsen 50 mg/kg (N=4)
Note: Statistical analysis based on Intent-To-Treat Population using ANCOVA test
p ≤0.016
TWO PATIENTS WHO SHOWED RAPID DECLINE ON THE 6MWT MAINTAINED PULMONARY FUNCTION THROUGH 48 WKS PULMONARY FUNCTION OUTCOME - % PREDICTED FVC 120
Patient 09
Patient 10
100 80 60 BL • • • • • •
Wk 12
Wk 24
Wk 36
Wk 48
Monozygotic identical twins in the 30 mg/kg cohort rapidly progressed, becoming non-ambulatory by 24 weeks. Excluded from modified intent-to-treat on ambulatory measures Increased dystrophin production in both boys at Weeks 24 and 48. Demonstrated stable pulmonary and cardiac function through week 48 No treatment-related adverse events through week 48 Continue on eteplirsen treatment and followed for safety and efficacy measures including pulmonary, cardiac and upper limb function
6-MINUTE WALK TEST CHANGE FROM BASELINE TO WEEK 48 SUBGROUP ANALYSIS IN mITT POPULATION FAVORS PLACEBO
Subgroup Comparisons:
FAVORS ETEPLIRSEN
p-value
50 mg/kg (n=4 vs. pbo n=4)
p ≤ 0.001
30 mg/kg (n=2 vs. pbo n=4)
p = ns
All eteplirsen (n=6 vs. pbo n=4)
p ≤ 0.001
Age 9.5 yrs at baseline (n=3 vs. pbo n=2)
p < 0.038
Age ≥ 9.5 yrs at baseline (n=3 vs. pbo n=2)
p = ns
Higher 6MWT at baseline (n=3 vs. pbo n=2)
p ≤ 0.001
Lower 6MWT at baseline (n=3 vs. pbo n=2)
p = ns
Genotype 49-50 deletion (n=2 vs. pbo n=3)
p ≤ 0.001
-100 -80
-60
-40
-20
0
20
40
Change from Baseline in 6MWT vs. Placebo (meters)
60
80
100 120 140 160
COMPREHENSIVE LABORATORY MONITORING WITH NO EVIDENCE OF TOXICITY CHEMISTRIES
KIDNEY FUNCTION • Urine and serum cystatin C • Urine KIM-1 • Urine protein
• C-reactive protein • Electrolytes • Creatinine
OTHER
LIVER FUNCTION • Gamma-glutamyl transferase
• CBCs • Coagulation profile • Pulmonary measures
MUSCLE ENZYMES
CARDIAC
• • • •
AST ALT LDH CK
• ECG • Echo
NO TREATMENT-RELATED ADVERSE EVENTS THROUGH 48 WEEKS TREATMENTEMERGENT ADVERSE EVENT Procedural pain Vomiting Hypokalemia Cough Back pain Fall Headache Balance disorder Diarrhoea Dermatitis Contact Pyrexia Hematoma Abdominal pain Nausea Rhinitis Polyuria Muscle Spasms Musculoskeletal Pain Proteinuria
ETEPLIRSEN FOR 24 WKS N=12 (%)
ETEPLIRSEN FOR 48 WKS N=8 (%)
PLACEBO FOR 24 WKS N=4 (%)
5 (42) 4 (33) 2 (17) 3 (25) 1 (8) 2 (17) 3 (25) 3 (25) 2 (17) 2 (17) 1 (8) 2 (17) 1 (8) 1 (8) 1 (8) 1 (8) 1 (8) 1 (8) 0
4 (50) 4 (50) 4 (50) 3 (38) 4 (50) 2 (25) 1 (12) 3 (38) 2 (25) 3 (38) 2 (25) 2 (25) 0 1 (12) 1 (12) 1 (12) 1 (12) 1 (12) 0
3 (75) 0 2 (50) 2 (50) 2 (50) 1 (25) 2 (50) 0 1 (25) 0 2 (50) 1 (25) 2 (50) 1 (25) 1 (25) 0 0 0 1 (25)
ETEPLIRSEN HAS BEEN WELL TOLERATED •
No treatment- related adverse events
•
No serous adverse events and no discontinuations
•
No treatment related changes detected on any safety laboratory parameters including liver-specific enzymes and kidney function
•
No proteinuria, change in blood coagulation profiles or thrombocytopenia observed
SUMMARY • Eteplirsen Phase IIB study met the primary endpoint of increase in novel dystrophin produced defined as a % of dystrophin positive fibers — Significant levels of dystrophin in all eteplirsen-treated patients after 24 weeks of treatment (average of 47.0% after 48 weeks of treatment and 38.3% after 24 weeks of treatment ) — Patients showed evidence of continued dystrophin production with a longer duration of treatment as demonstrated in the 30mg/kg cohort at weeks 24 and 48
• Eteplirsen achieved a significant clinical benefit on the primary clinical outcome, the 6-minute walk test (6MWT), over a placebo/delayed treatment cohort through week 48 — The 50mg/kg treatment cohort demonstrated an 89.4 meter benefit compared to patients who received placebo for 24 weeks followed by 24 weeks of treatment with eteplirsen — No statistically significant difference observed between the cohort of patients who received 30mg/kg weekly of eteplirsen and the placebo/delayed treatment cohort — Treatment effect was demonstrated across key subgroups of age, baseline 6MWT and genotype in the evaluable patients (mITT)
SUMMARY (CONTINUED) •
Eteplirsen proved well tolerated at both dose levels (up to 50mg/kg/wk over 48 weeks) with no treatment-related adverse events. — No treatment interruptions or discontinuations — No laboratory evidence of toxicity
THIS PHASE IIB STUDY DEMONSTRATES THE PROMISE OF ETEPLIRSEN TO BE A MAJOR ADVANCE IN DUCHENNE MUSCULAR DYSTROPHY BY TREATING THE UNDERLYING CAUSE, AND POTENTIALLY ALTERING THE COURSE, OF THE DISEASE