Changes in Retinal Sensitivity Associated With Cotoretigene Toliparvovec in X-Linked Retinitis Pigmentosa With RPGR Gene Variations
Authors: von Krusenstiern Lenore , Liu Jiajun , Liao Eileen , Gow James A. , Chen Guo , Ong Tuyen , Lotery Andrew J. , Jalil Assad , Lam Byron L. , MacLaren Robert E. ,   XIRIUS Part 1 Study GroupXOLARIS Study Group, Yusuf Imran H. , Cehajic-Kapetanovic Jasmina , Josan Amandeep S. , Martinez-Fernandez de la Camera Cristina , Rehman Salwah  , Wood Laura J. , Jolly Jasleen K. , Xue Kanmin  , Nanda Anika , Jasani Kirti , Menghini Moreno  , Buckley Thomas M.W. , Salvetti Anna Paola  , Thulasidharan Suresh  , Kurc Miguel  , Khandhadia Samir , Orsine Murta Dias Karla , Baltmr Abeir  , Mandal Nakul , Tsokolas Georgios  , Stanga Paulo , Ivanova Tsveta , EL-Faouri Muhannd , Shaarawy Sherif  , Black Graeme , Louise Davis Janet , Gregori Ninel , Mendoza-Santiesteban Carlos E.  , Rosa Potyra R. , Evans Kevin G. , Koenekoop Rob , Fischer Dominik , Holz Frank , Khan Kamron , Horowitz Jason , Pennesi Mark , Birch David , Gorin Michael , Stepien Kim , Duncan Jacque , Stout Tim , Bakall Benjamin , Bernstein Paul S. , Sankila Eeva-Maria , Hoyng Carel , Boon Camiel , Meunier Isabelle 
Published: February 2023

Importance

X-linked retinitis pigmentosa (XLRP) is a severe cause of early-onset RP in male individuals, characterized by degeneration of photoreceptors, an extinguished electroretinogram, and vision loss.

Objective

To assess the duration of improvements in retinal sensitivity associated with a single, subretinal injection of cotoretigene toliparvovec (BIIB112/AAV8-RPGR) gene therapy after vitrectomy surgery in the dosed eye over 12 months in part 1 of the Clinical Trial of Retinal Gene Therapy for X-linked Retinitis Pigmentosa Using BIIB112 (XIRIUS) study, compared with untreated fellow eyes and eyes from the untreated subgroup from the Natural History of the Progression of X-Linked Retinitis Pigmentosa (XOLARIS) study.

Design, Setting, and Participants

This was a post hoc analysis of the XIRIUS and XOLARIS studies. Part 1 of the XIRIUS study was a phase 1, dose-escalation study of 18 male participants 18 years or older enrolled between March 8, 2017, and October 16, 2018, with genetically confirmed RPGR-variant XLRP with active disease and best-corrected visual acuity better than or equal to light perception (cohort 1), 34 to 73 letters (20/40 to 20/200 Snellen equivalent; cohorts 2-3), or greater than or equal to 34 letters (better than or equal to 20/200 Snellen equivalent; cohorts 4-6). Participants from the noninterventional, multicenter, global, prospective XOLARIS clinical study who met the inclusion and exclusion criteria of part 1 of XIRIUS were included as a comparator group (n = 103). Safety assessments included all XIRIUS participants; post hoc associations of retinal sensitivity assessments in XIRIUS only included the 12 participants receiving the 4 highest doses of cotoretigene toliparvovec. Data were analyzed on June 30, 2021.

Main Outcomes and Measures

Incidence of dose-limiting toxicities (DLTs), treatment-emergent adverse events, changes from baseline in retinal sensitivity (as assessed by macular integrity assessment microperimetry), retinal sensitivity response (achievement of ≥7-dB improvement from baseline at ≥5 of 16 central loci), and low-luminance visual acuity were assessed over 24 months.

Results

A total of 18 participants (mean [SD] age, 31.9 [9.4] years; male, 100%) were enrolled and completed the XIRIUS study. A subgroup of 103 participants (mean [SD] age, 30.8 [11.4] years; male, 100%) from the XOLARIS study was included. Administration of the 4 highest doses of cotoretigene toliparvovec (n = 12) among the 18 XIRIUS participants was associated with early improvements in retinal sensitivity. One of 103 untreated participants (1%) in the XOLARIS subgroup achieved improved retinal sensitivity at month 12. No DLTs were noted at any dose, and serious adverse events of reduced visual acuity (n = 2) and noninfective retinitis (n = 1) occurred.

Conclusions and Relevance

Results suggest that early and sustained improvements in retinal sensitivity and low-luminance visual acuity in some participants through 12 months support consideration of additional clinical trials.

Trial Registration

ClinicalTrials.gov Identifier: XIRIUS: NCT03116113; XOLARIS: NCT04926129