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A gene therapy being jointly developed by MeiraGTx and Johnson & Johnson to treat an inherited disease of the retina that leads to blindness improved patients vision after six months, data that the companies say is enough to move the potentially long-lasting treatment into pivotal testing.

The condition, called X-linked retinitis pigmentosa, is part of a group of vision disorders that collectively represent the most common cause of inherited blindness. X-linked RP, or XLRP, the most aggressive form of retinitis pigmentosa, significantly impairs patients quality of life as the disease progresses. No treatments currently exist.

The MeiraGTx (NASDAQ: MGTX) treatment is designed for patients whose XLRP is caused by mutations in the gene RPGR, which cause about 70 percent of XLRP cases and up to 20 percent of all retinitis pigmentosa cases. MeiraGTxs gene therapy is delivered via subretinal injection.

A Phase 1/2 trial, underway at five sites in the US and UK, tested three doses in 10 male patients age 5 and older for safety and tolerability. In each patient one eyethe one with worse sightwas treated; the other eye was used as a control.

Secondary goals included retinal sensitivity, which after six months had improved or stabilized in five of the seven in the low and intermediate dose groups, according to the interim data. No improvement was observed in the high dose cohort; it wont be tested in future trials. Signs of improvement were detected at the first assessment, which took place at three months, improvements that were generally sustained or increased at the next evaluation.

Most of the adverse events recorded were associated with the surgical procedure used to deliver the treatment, according to MeiraGTx; two of three patients in the high-dose cohort experienced inflammation, which was controlled with steroids.

The data were presented at the annual meeting of the American Society of Retina Specialists, which was held virtually. The interim results support advancing the treatment into a Phase 3 triala first for MeriaGTx, which was founded about five years ago, president and CEO Zandy Forbes said on a conference call Friday.

Johnson & Johnson (NYSE: [[ticker:J&J]]) made a bet on the gene therapy pipeline being developed by MeiraGTx in January 2019, when the companies inked a $100 million deal giving the pharma giant rights to the biotechs investigational XLRP treatment, plus others in its pipeline, as part of a pact to jointly develop and commercialize gene therapies to treat inherited retinal diseases. Under the terms of that deal, MeiraGTx is eligible for up to $340 million more based on the programs progression.

Including the XLRP program, MeiraGTxwhich has offices in London and New Yorkis advancing six clinical-stage programs, half of them under its collaboration with J&J. The companys initial focus is on diseases that impact the eye, central nervous system, and salivary glands.

The first-ever gene therapy approved in the US, Spark Therapeutics voretigene neparvovec (Luxturna), was for patients with an inherited retinal disease that can lead to blindness. Its 2018 approval led to the companys acquisition the following year by Roche, which splashed out $4.8 billion for the Philadelphia-based firm. Spark priced its treatment at $850,000.

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Sarah de Crescenzo is an Xconomy editor based in San Diego. You can reach her at sdecrescenzo@xconomy.com.

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MeiraGTx, J&J See Phase 3 Test Ahead for Vision Loss Gene Therapy - Xconomy