EFFICACY & SAFETY

Read VILTEPSO’s efficacy data and four-year,
long-term, open-label extension study

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Primary Efficacy & Safety
Long-Term Data & Safety
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PRIMARY EFFICACY & SAFETY

VILTEPSO provided significant improvements in
dystrophin expression at week 24

VILTEPSO increased dystrophin where it’s needed—in the
skeletal muscle of DMD patients

Study 1: Mean increase in dystrophin expression to nearly 6% of normal with VILTEPSO (80 mg/kg/wk) vs 0.6% at baseline

Study 1 Graph 1 Study 1 Graph 1
P=0.01 normalized to myosin heavy chain*
  • Efficacy was assessed by validated western blot (normalized to myosin heavy chain) based on the change from baseline in dystrophin protein level, measured as percentage of the dystrophin level in healthy subjects at week 25
  • Mean change in dystrophin was 5.3% (SD 4.5) of normal levels (p=0.01)
    • Median change from baseline was 3.8%

Study design: A 2-period, randomized, double-blind, placebo-controlled, dose-finding study, with ambulant males aged 4 to <10 years with a confirmed mutation of the DMD gene amenable to exon 53 skipping who were receiving a stable dose of corticosteroids for ≥3 months (N=16). Patients received a once-weekly infusion of 40 or 80 mg/kg viltolarsen or placebo for a 4-week safety period followed by a 20-week open-label study to assess the efficacy and safety of viltolarsen. After completion of the 24-week study, patients could enroll in up to a 192-week extension study with efficacy assessments conducted every 12 weeks. Patients were required to remain on a stable dose of glucocorticoids for the duration of the study.

*P-value for change from baseline at week 25 was statistically significant

IFS=immunofluorescence staining; MS=mass spectrometry; NSAA=North Star Ambulatory Assessment; RT-PCR=reverse transcriptase-polymerase chain
reaction; 6MWT=6-minute walk test; TTCLIMB=time to climb 4 stairs; TTRW=time to run/walk 10 meters; TTSTAND=time to stand from supine;
QMT=quantitative muscle test (analysis to be conducted at study conclusion).

DYSTROPHIN WHERE IT MATTERS
Immunofluorescence staining showed VILTEPSO-induced increases in dystrophin levels were correctly localized to the muscle cell membrane, where dystrophin is needed to support muscle health.

100% of patients showed an increase in
dystrophin levels with VILTEPSO

Study 1: Dystrophin levels at 25 weeks vs baseline

Dystrophin expression (% of normal) normalized to myosin heavy chain

Study 1 Graph 2 Study 1 Graph 2
  • In a clinical study of patients aged 4 to <10 years, 100% of patients showed an increase in dystrophin levels with VILTEPSO, with a mean increase in dystrophin expression to ~6% of normal vs 0.6% at baseline
  • Exon 53 skipping was observed, on average, in 43.9% of dystrophin mRNA molecules in patients treated with VILTEPSO (80 mg/kg/wk), as measured by RT-PCR
  • The statistically significant increase in dystrophin expression was measured by western blot analysis, which is a validated, highly sensitive, and reproducible methodology

In the same 24-week study, secondary endpoint results
included evidence of dystrophin production and several motor function tests

Dystrophin Production Evidence

*Mean dystrophin levels as assessed by mass spectrometry (normalized to filamin C) increased from 0.6% (SD 0.2) of normal at baseline to 4.2% (SD 3.7) of normal by week 25, with a mean change in dystrophin of 3.7% (SD 3.8) of normal levels (nominal p=0.03, not adjusted for multiple comparisons); the median change from baseline was 1.9%.
 

Motor Function Tests

Functional tests were compared to Duchenne natural history data as the control group rather than to placebo. Definitive conclusions should not be drawn. Functional data are not in the US Prescribing Information.

†The control subjects for this trial were matched for age and corticosteroids from the CINRG DNHS registry.
‡Negative velocity means lower rate of velocity; positive velocity means higher rate of velocity.
§Negative time means less time; positive time means more time.
IINegative number means less distance traveled; positive number means greater distance traveled.
Negative number means a lower score relative to baseline; positive number means a higher score relative to baseline.
CINRG=Cooperative International Neuromuscular Research Group; DNHS=Duchenne Natural History Study.

Safety profile evaluated in two 24-week clinical studies

*Upper respiratory tract infection includes the following terms: upper respiratory tract infection, nasopharyngitis, and rhinorrhea.
†Injection site reaction includes the following terms: injection site bruising, injection site erythema, injection site reaction, and injection site swelling.
This profile includes data from a multicenter, parallel-group, open-label, dose-finding study conducted in Japan in ambulant and non-ambulant males aged 5 to <18 years with a confirmed mutation of the DMD gene amenable to exon 53 skipping. Non-ambulant is defined as patients with a 6MWT distance of <75 meters.

No treatment-related SAEs, drug-related TEAEs, discontinuations, or deaths occurred

SAE=serious adverse event;
TEAE=treatment-emergent adverse event.

LONG-TERM DATA & SAFETY

Four-year, long-term, open-label
functional assessment data

Functional tests were compared to Duchenne natural history data as the control group, rather than to placebo. Definitive conclusions should not be drawn. Functional data are not in the US Prescribing Information.

Time to stand over 205 weeks*

*The control subjects for this trial were matched for age, ambulatory status, corticosteroid use, and geographic location from the CINRG DNHS registry.  
†Negative time means less time; positive time means more time.
CINRG=Cooperative International Neuromuscular Research Group; DNHS=Duchenne Natural History Study.  
 

Time to run/walk 10 meters
over 205 weeks*

*The control subjects for this trial were matched for age, ambulatory status, corticosteroid use, and geographic location from the CINRG DNHS registry.  
†Negative time means less time; positive time means more time.  
CINRG=Cooperative International Neuromuscular Research Group; DNHS=Duchenne Natural History Study.  
 

Time to climb four stairs over
205 weeks*

*The control subjects for this trial were matched for age, ambulatory status, corticosteroid use, and geographic location from the CINRG DNHS registry.  
†Negative time means less time; positive time means more time.  
CINRG=Cooperative International Neuromuscular Research Group; DNHS=Duchenne Natural History Study.  

Study design: Boys aged 4 to <10 years (N=16) with DMD were enrolled in a randomized, double-blind, placebo-controlled, 4-week safety period of once-weekly infusion of 40 or 80 mg/kg viltolarsen, followed by a 20-week open-label study to assess the efficacy and safety of viltolarsen. After completion of the 24-week study, patients could enroll in up to a 192-week extension study (216 weeks total). Efficacy assessments were conducted every 12 weeks.

Safety assessment for
open-label, four-year extension data

No patients discontinued the study; no patients died; 3 patients had SAEs, none of which were considered related to study drug

Product Order Form

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Indication

VILTEPSO is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 53 skipping. This indication is approved under accelerated approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with VILTEPSO. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

For more information about VILTEPSO, see full Prescribing Information.

Important Safety Information

  • Warnings and Precautions: Kidney toxicity was observed in animals who received viltolarsen. Although kidney toxicity was not observed in the clinical studies with VILTEPSO, the clinical experience with VILTEPSO is limited, and kidney toxicity, including potentially fatal glomerulonephritis, has been observed after administration of some antisense oligonucleotides. Kidney function should be monitored in patients taking VILTEPSO. Serum creatinine may not be a reliable measure of kidney function in DMD patients.
  • Serum cystatin C, urine dipstick, and urine protein-to-creatinine ratio should be measured before starting VILTEPSO. Consider also measuring glomerular filtration rate before starting VILTEPSO. During treatment, monitor urine dipstick every month, and serum cystatin C and urine protein-to-creatinine ratio every three months.
  • Urine should be free of excreted VILTEPSO for monitoring of urine protein. Obtain urine either prior to VILTEPSO infusion, or at least 48 hours after the most recent infusion. Alternatively, use a laboratory test that does not use the reagent pyrogallol red, which has the potential to generate a false positive result due to cross reaction with any VILTEPSO in the urine. If a persistent increase in serum cystatin C or proteinuria is detected, refer to a pediatric nephrologist for further evaluation.
  • Adverse Reactions: The most common adverse reactions include upper respiratory tract infection, injection site reaction, cough, and pyrexia.
  • To report an adverse event, or for general inquiries, please call NS Pharma Medical Information at 1-866-NSPHARM (1-866-677-4276).

For more information about VILTEPSO, see full Prescribing Information.