- An experimental gene therapy being developed by Johnson & Johnson and U.K. biotech MeiraGTx for an inherited eye disease was safe and showed preliminary signs of improving visual function in an early-stage clinical trial, the companies said Tuesday.
- The treatment, which is meant to correct a severe form of the eye condition retinitis pigmentosa, was tested across several doses in a Phase 1/2 study involving 45 participants. Most side effects reported by trial investigators were related to the surgical delivery procedure, MeiraGTx said, while the addition of a preventive steroid regimen reduced inflammatory reactions.
- Encouragingly, treatment also led to improvements after six months in functional vision as measured by a maze and in retinal sensitivity — both goals of a larger Phase 3 study that’s being run by MeiraGTx and J&J. Detailed trial data will be reported a future medical meeting, the companies said.
The first gene therapy for an inherited disease approved by the Food and Drug Administration was Luxturna, a treatment for a form of blindness caused by genetic mutations.
The landmark clearance, coupled with the advantages of targeting the eye rather than other, harder-to-reach organs, helped spur development of many other gene therapies for ocular disorders. A number of those treatments are now advancing into later stages of clinical testing, including J&J and MeiraGTx’s.
Yet there have been setbacks, too. In May and again in June, two eye gene therapies being developed by Biogen failed in successive trials. One of the therapies, which Biogen acquired via a buyout of Nightstar Therapeutics, was for X-linked retinitis pigmentosa — the same condition being targeted by J&J and MeiraGTx.
A progressive and severe form of vision loss, X-linked retinitis pigmentosa, or XLRP, primarily affects boys and typically leads to blindness. The vast majority of XLRP cases are caused by mutations in a gene called RPGR that lead to the loss of light-sensing cells in the retina.
Both Biogen’s treatment and the one being developed by J&J and MeiraGTx are designed to correct the problem by shuttling functional copies of the RPGR gene directly into the eye via a subretinal injection. However, the two therapies rely on different inactivated viruses to do the job and use different forms of the gene, according to Luca Issi, an analyst at RBC Capital Markets.
“[Biogen’s] failure does not boost confidence, but we see some key differences that may lead to a different outcome,” he wrote in a May 12 note to clients. Along with the differences in design, J&J and MeiraGTx have previously reported evidence of functional improvement and disease reversion, he added.
The new data reported Tuesday could further boost expectations of success in the larger Phase 3 study that’s now ongoing. At six months, the companies reported significant differences between treated and control groups in the ability of participants to navigate a maze and in an assessment of their retinal sensitivity. Because the study’s main goal was safety, the efficacy measures are considered “nominal,” or not statistical proof of an effect.
Differences on another measurement known as BVCA were not significant, the companies said.
Among all patients treated with either the low or intermediate drug dose in the trial, treatment led to responses in retinal sensitivity by what’s known as “static perimetry” in 22% of treated patients compared to 0% of control participants after 26 weeks. The response rate in the former group improved to 48% after 52 weeks, MeiraGTx said.
A high dose that was previously tested had led to inflammation in two of three patients initially tested and was not selected for the dose expansion phase of the trial
Enrollment and patient dosing in the Phase 3 study, called LUMEOS, is ongoing and, if successful, the companies plan to submit their gene therapy to regulators for approval in 2024.
Along with MeiraGTx and J&J, Applied Genetic Technologies Corporation is also developing a gene therapy for XLRP and in May reported positive interim results from a small study.