Dear Duchenne Community,
We are pleased to share an update regarding the safety and efficacy data from our ongoing IGNITE DMD phase I/II clinical trial, as announced in the press release issued this afternoon. Additionally, we are excited to announce that we have resumed safe dosing at the 2E14 vg/kg dose, and that this patient experienced mild to moderate adverse events all of which have fully resolved. We are encouraged with the improved safety profile of SGT-001 under our previously reported amended protocol and second-generation manufacturing process, both of which were designed to enhance patient safety.
The data reported were collected from the first six patients dosed in IGNITE DMD twelve to twenty-four months after treatment and include data from three patients dosed at the low dose (5E13vg/kg) and three patients dosed at the high dose (2E14 vg/kg). Data from the delayed treatment cohort, analyzed as an untreated control cohort, were evaluated alongside representative natural history data. The six patients ranged in age from five to 14-years-old at time of dosing.
We are looking forward to hosting a webinar with Parent Project Muscular Dystrophy tomorrow, Tuesday, March 16, at 1pm ET to review the data included below in more detail and take questions from the community.
- Among patients in the low and high dose cohorts, North Star Ambulatory Assessment (NSAA) scores at 1 year suggest benefit after treatment as compared to trajectories typically observed in natural history data. Natural history analyses suggest that patients similarly aged to those enrolled in IGNITE DMD would normally be expected to have either plateaued in gains or exhibit a 3 to 3.7-point decline year over year. Patients in the untreated control cohort exhibited a mean decline of 4.0 points from baseline to 1 year, while patients in the low dose cohort exhibited a mean improvement of 1.0 point over the same period of time. Patients in the high dose exhibited a mean improvement of 0.3 as compared to their baseline values.
- Mean increase in the 6-Minute Walk test (6MWT) distance was above the generally accepted minimally clinically important difference (MCID) of 30 meters in both the low and high dose cohorts after treatment. While patients in the untreated control cohort exhibited a decline of 8.5 meters from baseline to 1 year, patients in the low dose cohort exhibited a mean improvement of 37 meters and patients in the high dose cohort exhibited an improvement of 49.7 meters over the same 12 month period.
- With respect to spirometry testing of pulmonary function, the majority of patients in both dose groups exhibited improved forced vital capacity (% predicted FVC) at one year when declines in pulmonary function would otherwise be typically observed in patients with Duchenne. From baseline to 1 year, patients in the untreated control cohort exhibited a mean decline of 10.7% on an absolute basis, while patients in the low dose and high dose cohorts exhibited a mean improvement of 3.9% and 16.7%, respectively, over the same period.
- As previously reported, biopsies of skeletal muscle three months after a single infusion of SGT-001 at a dose of 2E14vg/kg demonstrated widespread distribution of microdystrophin-positive muscle fibers with co-localization of nNOS and β-sarcoglycan in the muscles of these patients.
- Creatine kinase (CK) assessments of the six patients provide potential physiological evidence of a positive or stabilizing effect after one year of treatment with a single high dose infusion of SGT-001. An average sustained CK decline of approximately 50% in patients in the high dose cohort was observed.
Patient Reported Outcome (PROMs) Data
Patient reported outcomes measures taken after one year of treatment revealed a trend towards dose-ordered improvements in motor function subscales and fatigability assessments, providing real-world evidence to support the clinical and biomarker findings of varying degrees of benefit in low and high dose patients.
- Meaningful improvements in the Pediatric Outcomes Data Collection Instrument (PODCI), a validated PROM that contains questions to assess how caregivers and children evaluate the child’s ability to walk, stand, and perform activities of daily living, as well as recreational activities. Motor function scores reflect the gains seen in 6MWT and benefit of NSAA observed in all dosed patients.
- Semi-structured, qualitative interviews conducted by Modus Outcomes Ltd with patients and caregivers about the impact of Duchenne on functioning demonstrated overall improvement in functional activity and school-related impacts (e.g., lower limb mobility, keeping up with peers, climbing stairs, sports) in low- and high-dose cohorts, with subjective decreased fatigability in all patients of both treatment cohorts.
The totality of data collected, and the re-initiation of safe dosing support the continued enrollment of patients into the IGNITE DMD study. We encourage you to regularly visit clinicaltrials.gov (NCT03368742) for updates as they become available. If you have any questions, please feel free to contact us directly at Community@solidbio.com.
We look forward to speaking with the community tomorrow afternoon during the webinar hosted by PPMD.
Your Solid Biosciences Team