Canadian-based biotechnology company QLT has completed enrolment in its natural history study in subjects with Inherited Retinal Disease (IRD), phenotypically diagnosed with Retinitis Pigmentosa (RP), or Leber Congenital Amaurosis (LCA), due to underlying Retinal Pigment Epithelial 65 protein (RPE65) or Lecithin: Retinol Acyltransferase (LRAT) gene mutations.
The objective of the retrospective, uncontrolled, multicentre study is to collect data on the natural succession of the disease in subjects over time, from childhood through to adulthood.
The study involved both subjects who had previously received treatment in QLT-sponsored clinical trials with QLT's synthetic oral retinoid product, QLT091001, and subjects who had not received any prior therapeutic treatment.
For subjects who had received treatment with QLT091001, the natural history study included a retrospective review of subjects' medical records prior to and after treatment with QLT091001.
QLT stated that historically, it has been accepted that subjects born with IRD due to RPE65 or LRAT gene mutations would be expected to show an overall decline in visual field and visual acuity, but at varying rates and over differing periods of time.
Moreover, these patients may also demonstrate growing retinal atrophy as the disease progresses.
The aims of the natural history study were to collect data from these patients retrospectively, but under a formal protocol, thereby providing an opportunity to better observe and understand the long-term natural disease progression of untreated patients.
The trial will also provide comparative data to further assess the extent that the treatment with QLT091001 may prolong or improve visual function, relative to the underlying natural disease progression in these subjects.
The multi-site study sought to enrol up to 60 subjects from established IRD patient populations at ten clinical study sites in Europe, the US and Canada.
Altogether, 59 patients were enrolled in the study, 25 of whom had participated in earlier clinical studies with QLT091001, and 34 of whom were treatment naive.
Data was gathered from patient records for several visual outcome measures, with particular reference to changes in visual field and visual acuity for individual subjects over various years, and in some cases, decades, often starting in childhood.
QLT has completed its preliminary analysis and believes that the data suggests that these patients, without other interventions, demonstrate a continuing decline in visual field and eventually visual acuity over time.
The company expects to present the results for discussion with selected national European Agencies, and later with the US FDA.
Additionally, QLT is planning to begin a pivotal, Phase III multi-centre, placebo-controlled, double-masked clinical study for this indication, potentially in the third quarter of this year.
The objective of this study will be to further evaluate the efficacy, with particular reference to changes in visual field and visual acuity, and safety of QLT091001, with a goal of supporting future applications for full approval of QLT091001, for this indication to the EMA and US FDA.
The pivotal trial is expected to enrol 48 patients at around 12 sites in the EU, the US and Canada.