MeiraGTx (Nasdaq: MGTX) has announced that additional clinical data from the Phase 1/2 trial of botaretigene sparoparvovec for the treatment of X-linked Retinitis Pigmentosa (XLRP) were presented last week at the Association for Research in Vision and Ophthalmology, Annual Meeting (ARVO). MeiraGTx and Janssen Pharmaceuticals, Inc., are understood to jointly develop the treatment by “botaretigene sparoparvovec”, as part of a broader collaboration to develop and commercialize gene therapies for the treatment of inherited retinal diseases. According to the company, MeiraGTx remains eligible to receive additional development and commercial milestones for botaretigene sparoparvovec as well as for other programs as part of the collaboration agreement.
Botaretigene sparoparvovec, was formerly referred to as AAV-RPGR, applied as an investigational gene therapy for the treatment of patients with XLRP, caused by disease-causing variants in the eye-specific form of the RPGR gene (RPGR ORF15). Botaretigene sparoparvovec is designed to deliver functional copies of the RPGR gene to the subretinal space in order to help improve and/or preserve vision. The experimental treatment is being evaluated in the Phase 1/2 MGT009 clinical trial (NCT03252847), an open-label, multi-center dose escalation study with a randomized, multi-dose expansion cohort which included a deferred treatment control to determine the safety and efficacy of botaretigene sparoparvovec in adults and children with XLRP caused by variants in the RPGR gene. The “Lumeos trial” (NCT04671433), a Phase 3 randomized, controlled study of botaretigene sparoparvovec for the treatment of XLRP associated with variants in the RPGR gene, is actively dosing patients and has been granted for Fast Track and Orphan Drug designations by the FDA and PRIority MEdicines (PRIME), Advanced Therapy Medicinal Product (ATMP) and Orphan designations by the European Medicines Agency (EMA).
In the most recent announcement, the open-label Phase 1/2 trial applies subretinal injections of 1 of 3 doses to the worse-seeing eye. Changes in retinal sensitivity and the volumetric analysis of the central 30 degrees of the retinal field were examined and compared to the untreated surrounding area as well as the retina of the untreated fellow eye. According to the company, “data from the study indicates improvements in photoreceptor function assessed through 12 months post-treatment suggesting local efficacy of botaretigene sparoparvovec gene therapy in XLRP patients. The treatment effect is observed within the treated bleb and may also extend beyond the margins of the bleb following surgery owing to subretinal extension before retinal reattachment”.