Santhera: Positive key results from pivotal study of Duchenne Muscular Dystrophy treatment

VISION-DMD is a pivotal Phase 2b study designed to demonstrate efficacy and safety of vamorolone compared to placebo and prednisone (active control) in the treatment of DMD. In the first 24-week double-blind period, of which the topline data readout is presented here, 121 ambulant boys aged 4 to <7 years with DMD were randomized to receive vamorolone (low dose 2 mg/kg/day or high dose 6 mg/kg/day) or prednisone (0.75 mg/kg/day) or placebo. A second period of 24 weeks, where all participants receive vamorolone treatment on either of the two dose levels, will continue to capture additional longer term safety and tolerability data.

Vamorolone demonstrates efficacy across primary and secondary endpoints and over a broad dose range
The study met its primary endpoint of superiority in change of time to stand from supine positioning to standing (TTSTAND) velocity with vamorolone 6 mg/kg/day versus placebo (p=0.002) with a treatment difference of 0.06 [95% CI: 0.02–0.10] rises/second from baseline. This corresponds to a clinically relevant improvement in TTSTAND in the vamorolone 6 mg/kg/day group from 6.0 to 4.6 seconds and a corresponding deterioration in the placebo group from 5.4 to 5.5 seconds. The study also demonstrated superiority of vamorolone versus placebo across multiple secondary endpoints which include (in the order of pre-defined hierarchy): TTSTAND velocity for 2 mg/kg/day (p=0.02), 6MWT for 6 mg/kg/day (p=0.003) and 2 mg/kg/day (p=0.009), TTRW for 6 mg/kg/day (p=0.002). The clinical results establish the efficacy of vamorolone over a wide, threefold dose range from 2 to 6 mg/kg/day. No statistically significant differences were observed between vamorolone 6 mg/kg/day and prednisone across the above endpoints.

Vamorolone showed a favorable safety and tolerability profile over prednisone
The study completion rate at 24 weeks was 94% (or 114 of 121 participants). Vamorolone at both doses of 2 and 6 mg/kg/day showed a favorable safety and tolerability profile. In the vamorolone groups, no grade 3 or higher treatment emergent adverse events (TEAEs) or adverse events leading to study discontinuation were observed. The total number of TEAEs was lower in the vamorolone 2 mg/kg/day (events n=96) and 6 mg/kg/day (n=91) groups compared to prednisone (n=120). In a prespecified analysis of clinically relevant adverse events (moderate, severe, serious or leading to discontinuation due to safety), defined for the EMA and conducted by Santhera, vamorolone 6 mg/kg/day was significantly superior to prednisone (n=6 vs n=19, p=0.02).

As previously published, in open-label studies of 2.5 years duration (113 patient years), vamorolone did not show stunting of growth as reported with conventional corticosteroids. Particularly noteworthy, this was validated in the current 24-week double-blind study where vamorolone 6 mg/kg/day versus prednisone 0.75 mg/kg/day showed a significant difference in growth velocity (p=0.02). “Stunting of growth is a major concern of families and patients treated with corticosteroids, and we are delighted to see this superiority of vamorolone proven in this double-blind study,” said Paula Clemens, MD, study Co-Chair, and Vice Chair of VA Affairs and Professor of Neurology, University of Pittsburgh School of Medicine.

“Today’s news is a tremendous milestone for patients and Santhera as we further advance vamorolone as a foundational treatment option in DMD. The treatment effect translates into the potential to delay disease progression by about two years and indicates disease modifying potential of vamorolone,” said Dario Eklund, Chief Executive Officer of Santhera. “We now look forward to working with regulatory authorities to bring vamorolone to DMD patients, first in the US and subsequently in Europe.

“We are thrilled about the positive results of the VISION-DMD study as it represents a culmination over a decade of scientific research,” said Eric Hoffman, PhD, President and CEO at ReveraGen BioPharma and Professor of Pharmaceutical Sciences, Binghamton University – State University of New York. “We are grateful to have been able to gather such important data and would like to thank all VISION-DMD participants, their families and caregivers, as well as investigators and study personnel, for their commitment to this ongoing program.”

“The strength of evidence for both efficacy and safety of vamorolone over such a wide dose range from 2 to 6 mg/kg/day allows clinicians to individually tailor treatment of Duchenne patients by starting at the higher 6 mg/kg/day dose of vamorolone with equivalent efficacy to daily prednisone and titrate the dose according to how well the treatment is tolerated whilst maintaining optimal efficacy. I am enthusiastic that this approach may allow patients to avoid side effects that currently lead to discontinuing steroid treatment, meaning they are able stay on for longer,” said Craig McDonald, MD, Professor and Chair, Department of Physical Medicine & Rehabilitation and Director of Neuromuscular Disease Clinics, UC Davis Health, USA.

Santhera plans to submit a New Drug Application (NDA) in the US in Q1-2022, requesting a priority review based on the fast track designation granted by the FDA. The VISION-DMD study continues to 48 weeks and will, subject to a positive outcome, deliver data for the submission of a marketing authorization application in Europe in Q2-2022. Upon approval, Santhera intends to commercialize vamorolone for the treatment of DMD through its own organization in the United States and main markets in Europe, and is seeking collaborations outside those regions for DMD and for additional indications worldwide. Santhera estimates the peak sales potential for vamorolone in the indication DMD alone to be in excess of USD 500 million in the US and the largest five European countries combined.

Vamorolone has been granted Orphan Drug status in the US and in Europe, and has received Fast Track and Rare Pediatric Disease designations by the US FDA and Promising Innovative Medicine (PIM) status from the UK MHRA. On September 2, 2020, Santhera signed agreements with ReveraGen and Idorsia that granted Santhera an exclusive license to vamorolone for all indications worldwide.

About Vamorolone
Vamorolone is a first-in-class dissociative steroid which retains the anti-inflammatory activity of corticosteroids while decreasing the deleterious side effects. As such, vamorolone could emerge as a promising alternative to existing corticosteroids, the current standard of care in children and adolescent patients with DMD. There is substantial unmet medical need in this patient group as high-dose corticosteroids have significant systemic side effects that diminish patient quality of life. Vamorolone was discovered by US-based ReveraGen BioPharma, Inc. and is being developed in collaboration with Santhera, which owns worldwide rights to the drug candidate in all indications. The vamorolone development program has received funding from several international non-profit foundations and patient organizations, the US National Institutes of Health, the US Department of Defense and the European Commission’s Horizon 2020 program.