X-linked retinitis pigmentosa Phase 1/2 clinical trial provides positive 12-month data

Applied Genetic Technologies Corp., a biotechnology company conducting human clinical trials of adeno-associated virus (AAV)-based gene therapies for the treatment of rare retinal diseases, has reported additional positive data from the ongoing X-linked retinitis pigmentosa (XLRP) Phase 1/2 clinical trial.

The trial includes 12-month data from Groups 5 and 6 reflecting a 50% response rate among patients who met the inclusion criteria for the Skyline and Vista trials and 24-month data from two of three Group 4 patients providing preliminary evidence of response durability. The third patient was not a responder at Month 12 and no early data are currently available for the remaining four Group 4 patients.

Taken together, these data add to the body of evidence suggesting that durable improvements in visual sensitivity and visual acuity may be achieved in patients receiving AGTC’s XLRP product candidate while continuing to demonstrate a favorable safety profile.

According to Robert Sisk, MD, Associate Professor of Ophthalmology, University of Cincinnati and Cincinnati Eye Institute, and an investigator on AGTC’s XLRP Phase 1/2 clinical trial, the rate and durability of response for improvements in retinal sensitivity are very promising, as are continued trends of increased visual acuity at Month 12 in some patients.

“Gene therapy holds great promise in improving outcomes for these early and moderate staged XLRP patients, who today have no FDA-approved treatment options,” he said in a statement. “I believe that the data presented today are an important advance for the field of gene therapy for retinitis pigmentosa, and I look forward to presenting the full Month 12 Phase 1/2 data at the American Academy of Ophthalmology annual meeting later this year.”

According to Sue Washer, president and CEO of AGTC, a growing body of data supports the best-in-class potential of our XLRP therapy product candidate and we are executing a robust plan to advance this program as rapidly as possible toward commercialization.

“The 50% response rate observed in Groups 5 and 6, coupled with the 12-month visual sensitivity and visual acuity data from these groups and 24-month data from three Group 4 patients, position the Phase 2/3 Vista trial and expanded Phase 1/2 Skyline trials for success,” Washer said in a statement. “The clear differences in visual sensitivity and visual acuity between the treated and untreated eyes at 12 months in Groups 5 and 6 demonstrate a biological response to our XLRP candidate.”

Groups 5 and 6 Month 12 Data
According to AGTC, data at 12 months were available from seven patients in Group 5 and four patients in Group 6. One patient in Group 5 and two patients in Group 6 would not meet the inclusion criteria for the Skyline and Vista trials, resulting in a total of eight patients who were included in the responder analysis. Four of these eight patients (50%) were considered responders, all four of whom met the strict criteria of at least a 7 decibel (dB) improvement in at least 5 loci. One additional patient did not meet these criteria but had a statistically significant improvement in retinal sensitivity in the treated compared with the untreated eye at 12 months.

Consistent with previously reported 6-month data from Groups 2, 4, 5 and 6, assessment of BCVA in these groups at 12 months continue to provide supportive evidence of improved visual acuity in these patients. The difference between treated and untreated eyes is statistically significant. According to the company, these data, together with the favorable safety profile, differentiate its XLRP candidate from competitors.

Group 4 Month 24 Data
Data from three of the seven Group 4 patients were available for analysis at Month 24, including two who were responders at Month 12 (one by the 7dB change in at least 5 loci response criteria and the other based on improved retinal sensitivity in the treated compared with the untreated eye). These two patients are still responders at Month 24 according to the same criteria; the third patient who has reached Month 24 was not a responder at Month 12 or Month 24. To the best of the Company’s knowledge, this is the first XLRP gene therapy clinical trial to demonstrate continued durability of response at this time point.

Safety Data
The company reported that data from all 28 patients across six dose groups continue to demonstrate a favorable safety profile with no dose-limiting inflammatory responses observed. This safety profile, which has shown no clinically significant inflammation not manageable with steroids, continues to be observed out to 24 months.

Going forward, AGTC said it expects to present 12-month trial results from the ongoing Phase 1/2 clinical trial at the American Academy of Ophthalmology annual meeting in November. 

The company also will provide Skyline trial results from the 3-month masked interim analysis in 4Q 2021, and Skyline trial results from the 12-month data in 3Q 2022; and Vista trial results from the 6-month masked interim analysis in 4Q 2022.