ProQR Therapeutics announced results from a planned interim analysis of its phase 1/2 trial of QR-110 in patients with Leber’s congenital amaurosis 10 (LCA10) due to the p.Cys998X mutation in the CEP290 gene. LCA10 typically leads to childhood blindness and has no available treatment options.
In the trial, QR-110 demonstrated rapid and sustained improvement in vision in patients with LCA10, as measured by visual acuity and the mobility course performance, as well as being well-tolerated with no serious adverse events recorded. Results from this interim analysis were presented at the Retinal Degeneration 2018 meeting in Killarney, Ireland, by principal investigator Artur Cideciyan, PhD, research professor of ophthalmology at the Scheie Eye Institute, University of Pennsylvania.
“The results of this interim analysis are encouraging and met our decision criteria to stop enrollment in this study and progress to a pivotal phase 2/3 trial,” David Rodman, MD, executive vice president of research and development of ProQR, said in a company news release. “We observed a clinically meaningful improvement in vision in the treated eye as measured by both mechanistic and potential registration endpoints. Consistent with predictions based on our patient derived optic-cup models, improvement in visual function was observed as early as 2 months after treatment and was maximal and stable by 3 months and thereafter. We are very grateful to the study participants, their caregivers, and the investigators and their staff for the support in the development of QR-110 in this trial.”
Thaddeus P. Dryja, MD, professor of ophthalmology at Harvard Medical School and Massachusetts Eye and Ear and member of the National Academy of Sciences, commented, “These results are the first human data to evaluate the clinical utility of RNA-based therapeutics in a human photoreceptor disease, particularly one with a severe unmet medical need. While a confirmatory trial will be required to establish the full potential of QR-110 in LCA10, these results suggest that therapeutic oligonucleotides have the potential to be broadly applicable to a wide spectrum of inherited retinal disorders.”
Based on the emerging findings from the phase 1/2 trial, the company agreed with the FDA to submit a protocol to progress to a pivotal phase 2/3 trial. In light thereof, the originally planned interim analysis at 6 months treatment was accelerated to the point when eight patients had reached 3 months of treatment. Given comparable activity was observed in the first two dose levels, the trial did not escalate up to the high dose and trial enrollment has stopped, in anticipation of the start of a phase 2/3 trial.
Results from the interim analysis
Efficacy data: Approximately 60% of subjects showed a clinically meaningful response in visual acuity and mobility course endpoints at 3 months of treatment and there was general concordance across the endpoints. Efficacy signals were observed within 2 months with maximal benefits seen within 2 to 3 months post treatment initiation. A secondary analysis assessing all available data demonstrated that observed effects on efficacy were durable beyond three months.
Visual acuity: In the majority of patients, there was a substantive overall improvement in best corrected visual acuity (BCVA) as assessed by the Berkeley Rudimentary Vision Test (BRVT) and the Early Treatment of Diabetic Retinopathy Study (ETDRS) eye chart. At 3 months of treatment, the mean improvement (and standard error of mean, SEM) was -0.67 LogMAR (SEM 0.32) with 62.5% of subjects showing an improvement of greater than -0.3 LogMAR from baseline, which is considered clinically meaningful. The mean change in the contralateral eye was 0.02 LogMAR (SEM 0.05).
Mobility course: Effects on visual acuity correlated with effects on mobility. In the majority of patients there was a substantive overall improvement in functional visual performance as assessed using a series of mobility courses at increasing difficulty and multiple light intensities. At 3 months of treatment, the mean improvement in navigating the mobility course was 2.6 levels (SEM 1.2) with 57.1% of subjects improving by more than 2.0 levels, which is regarded as clinically meaningful. The mean change in the contralateral eye was 1.36 (SEM 1.04).
Full field stimulus test (FST): Improvements in visual function were supported by a meaningful increase in the ability to detect flashes of red or blue light as determined by the FST. After 3 months of treatment, mean improvement in red light sensitivity was -0.74 log Cd/m2 (SEM 0.35) and improvement in blue light sensitivity was -0.91 log Cd/m2 (SEM 0.38).
Ocular Instability (OCI): Additionally, the majority of patients improved on nystagmus (involuntary eye movements in low vision patients), with a mean change of log -0.14 mm (SEM 0.08) in OCI.
Safety: Out of the 10 subjects dosed in the study, one subject has received all four doses and three have received three doses, representing a combined total of more than 1,500 treatment days. So far QR-110 was well tolerated with no serious adverse events related to treatment or procedure. All data and safety monitoring committee (DSMC) reviews were completed with no restrictions on further dose escalation or pediatric dosing.
Start of Phase 2/3 pivotal “ILLUMINATE” trial
The company has agreed with the FDA to submit a protocol to start a phase 2/3 trial that could serve as the sole registration trial, to be called “ILLUMINATE.” The preliminary design for ILLUMINATE is a double-blind, controlled, 12-month study. The trial is expected to initially enroll 30-40 patients with LCA10 due to one or two copies of the p.Cys998X mutation and could be adaptively repowered. The primary endpoints in this trial are expected to include the mobility course and visual acuity, among others. The trial is expected to be conducted at centers in North America and select European countries. Pending completing discussions on the design of the study with the FDA in 2018, the trial is expected to start in the first half of 2019. In parallel to the pivotal phase 2/3 trial, the company plans to start a trial in patients <6 years old.