Eye On the Cure Research News

Jul 17, 2020

MeiraGTx and Janssen Pharmaceuticals Report Promising Interim Results from its Phase 1/2 Clinical Trial for XLRP Gene Therapy

A Phase 3 trial for the treatment is planned

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MeiraGTx and Janssen Pharmaceuticals report stable or improved retinal sensitivity for five of seven participants — those in the low and intermediate dose groups — in a Phase 1/2 clinical trial for its X-linked retinitis pigmentosa (XLRP) gene therapy. The therapy is for XLRP caused by mutations in the gene RPGR.

The Phase 1/2 trial is underway at five sites in the US and the UK. Males as young as five are being enrolled. Thanks to the encouraging interim results, the company is planning a Phase 3 trial for the treatment.

MeiraGTx’s gene therapy is administered by multiple subretinal injections in the central retina. For example, one patient received four subretinal injections. The hope is that multiple injections will get the treatment to a larger area of the retina than a single injection, thereby stabilizing or improving more vision.  The gene therapy is designed to be effective for several years, perhaps the lifetime of the patient.

XLRP is a common and aggressive form of retinal disease. There is a great unmet need and these results provide hope for those affected.

Brian Mansfield, PhD, executive vice president of research and interim chief scientific officer, Foundation Fighting Blindness

The subretinal injections deliver copies of a healthy RPGR gene into the patient’s retina to augment the mutated RPGR copies. Human-engineered viral containers — derived from an adeno-associated virus or AAV — deliver the RPGR copies into the photoreceptors, the vision-enabling cells affected by XLRP.

Retinal sensitivity of the patients in the Phase 1/2 trial was evaluated by microperimetry which measured levels of retinal sensitivity at 185 different points in the patients’ central retinas.

Inflammatory responses were observed in two of the three patients in the clinical trial’s high dose cohort, which were effectively treated with extension of the steroid cover.

“We are encouraged by the early and meaningful clinical trial results for MeiraGTx’s XLRP gene therapy,” says Brian Mansfield, PhD, executive vice president of research and interim chief scientific officer at the Foundation Fighting Blindness. “XLRP is a common and aggressive form of retinal disease. There is a great unmet need and these results provide hope for those affected.”

As an X-linked condition, XLRP primarily affects males, although some females may be affected, sometimes significantly.