MeiraGTx Announces Positive Clinical Data Demonstrating Treatment with AAV-RPGR Investigational Gene Therapy Improves Vision in X-Linked Retinitis Pigmentosa Patients Data being presented at the American Society of Retin

Announces Positive Clinical Data Demonstrating Treatment with AAV-RPGR Investigational Gene Therapy Improves Vision in X-Linked

Retinitis Pigmentosa Patients

Data being presented at the American

Society of Retina Specialists (ASRS) 2020 Virtual Annual Meeting

Significant improvements demonstrated

after treatment in Phase 1/2 clinical trial

Based on encouraging safety and

efficacy profile, MeiraGTx and Janssen expect to progress AAV-RPGR into Phase 3 Lumeos clinical trial

MeiraGTx to host investor conference

call on Friday, July 17 at 8:00 a.m. ET

LONDON and NEW YORK, July

17, 2020 (GLOBE NEWSWIRE) -- MeiraGTx Holdings plc (Nasdaq: MGTX), a vertically integrated, clinical stage gene

therapy company, today announced six-month data from the ongoing Phase 1/2 clinical trial (NCT03252847) of AAV-RPGR, an

investigational gene therapy in development for the treatment of patients with X-linked retinitis pigmentosa (XLRP) with genetically

confirmed variants in the RPGR gene. Significant improvement in vision was demonstrated in the dose escalation phase of

the trial and AAV-RPGR was found to be generally well tolerated. These initial results from the trial are being presented as a

late-breaker oral presentation at the American Society of Retina Specialists (ASRS) 2020 Virtual Annual Meeting.

MeiraGTx and Janssen Pharmaceuticals,

Inc. (Janssen), one of the Janssen Pharmaceutical Companies of Johnson & Johnson, are jointly developing AAV-RPGR as part

of a broader collaboration to develop and commercialize gene therapies for the treatment of inherited retinal diseases.

The ongoing Phase 1/2 MGT009

clinical trial consists of three phases: dose-escalation, dose-confirmation, and dose-expansion. In the dose-escalation phase

(n=10), adults were administered low, intermediate, or high dose AAV-RPGR. Each patient was treated with subretinal delivery of

AAV-RPGR in the eye that was more affected at baseline. The patient's other eye served as an untreated control. The primary

endpoint of the trial is safety, with secondary endpoints assessing changes in visual function at pre-specified timepoints post-treatment.

Baseline values were determined in triplicate.

At six months, significant improvement

in retinal sensitivity was demonstrated in patients treated with low and intermediate dose AAV-RPGR. Improvement was evident at

first post-treatment perimetry assessments at three months, with improvements generally sustained or increased at six months.

Significant differences were observed in retinal sensitivity between treated and untreated eyes over time. Based on the robust

safety and efficacy signals observed in the dose escalation portion of the study, the low and intermediate doses were selected

for use in the ongoing randomized, controlled dose-expansion phase of the trial.

"XLRP is characterized

by early-onset visual field loss, with most patients progressing to blindness and associated loss of independence by young adulthood,"

said Michel Michaelides1, BSc MB BS MD(Res) FRCOphth FACS, MGT009 trial investigator, Consultant Ophthalmologist, Moorfields

Eye Hospital and Professor of Ophthalmology, University College London. "Six-month data demonstrate AAV-RPGR may improve

visual function in XLRP patients. Initial data also suggest treatment with AAV-RPGR has the potential to stabilize or slow progressive

vision loss. These results support AAV-RPGR as an important advancement in the treatment of XLRP, for which there is no currently

available therapeutic option."

Based on the encouraging safety

and efficacy data demonstrated in the MGT009 trial to date, MeiraGTx and Janssen expect to advance AAV-RPGR into the Phase 3 Lumeos

clinical trial for the treatment of patients with XLRP caused by mutations in RPGR gene.

"We are pleased to share

these encouraging initial results from our XLRP gene therapy trial and look forward to advancing this program into a Phase 3 trial,"

said Alexandria Forbes, Ph.D., president and chief executive officer of MeiraGTx. "These early data suggest AAV-RPGR has

the potential to address some of the key functional manifestations of this severe disease for which there is no currently available

therapy. I'd like to thank the investigators, patients and families who dedicate their time to our clinical trials and who

continue to support us in our efforts to develop therapies that have the potential to make a meaningful difference and improve

the lives of people with serious diseases."

Data obtained to date suggest

AAV-RPGR is generally well-tolerated. Most adverse events (AEs) were related to the surgical delivery procedure, were transient

and resolved without intervention. There were no dose-limiting events. Inflammatory responses to therapy were observed in two

out of three patients in the high dose cohort, which may have been associated with decreased activity of AAV-RPGR in these patients.

Inflammation was effectively managed with an extended steroid protocol.

Six-month data from the dose

escalation portion of the study (n=10) demonstrated meaningful improvement from baseline in retinal sensitivity in the low (n=3)

and intermediate (n=4) dose cohorts. Importantly, these improvements were evident when assessed with two perimetry approaches

(static perimetry and microperimetry) and three analysis metrics (mean retinal sensitivity, central 30 hill-of-vision volumetric

measure (V30), and pointwise comparison).

1 Professor Michaelides

is a scientific founder of and consultant to MeiraGTx.

Perimetry is a sensitive standard-of-care

measure of retinal function that reproducibly determines retinal sensitivity both cross-sectionally and longitudinally, thereby

accurately defining disease progression over time.

ASRS Presentation Information:

Late-Breaker Presentation

Title: AAV-RPGR Gene Therapy

for RPGR-Associated X-Linked Retinitis Pigmentosa: 6-month Results From a Phase 1/2 Clinical Trial

Presenter: Michel Michaelides,

UCL Institute of Ophthalmology; Moorfields Eye Hospital

Date: Oral presentation

available to ASRS meeting attendees on the virtual meeting site as of July 17, 2020; live Q&A session to take place July 25,

Session: Hereditary Retinal

Conference Call Information:

MeiraGTx will host a conference

call and webcast to review Professor Michaelides' ASRS presentation on July 17, 2020 at 8:00 a.m. ET. The webcast can be

accessed by visiting the Investors page of the Company's website at https://investors.meiragtx.com/events-presentations.

Alternatively, please call 1 (866) 796-1272 (U.S.) or 1 (409) 937-8924 (International) to listen to the conference call. The conference

ID number for the call is 4669817. A replay of the webcast and accompanying presentation materials will be available on the Company's

website for 30 days following the conference call.

is an investigational gene therapy for the treatment of patients with XLRP caused by mutations in the eye specific form of the

RPGR gene (RPGR ORF15). AAV-RPGR is designed to deliver functional copies of the RPGR gene to the subretinal

space in order to improve and preserve visual function. MeiraGTx and development partner Janssen are currently conducting a Phase

1/2 clinical trial of AAV-RPGR in patients with XLRP with mutations in RPGR ORF15. AAV-RPGR has been granted Fast Track

and Orphan Drug designations by the U.S. Food and Drug Administration (FDA) and PRIME, ATMP and Orphan designations by the European

Medicines Agency (EMA).

Excludes one subject with panuveitis in the low dose cohort

the Phase 1/2 MGT009 Clinical Trial

MGT009 is a multi-center, open-label

Phase 1/2 trial (NCT03252847) of AAV-RPGR gene therapy for the treatment of patients with XLRP associated with disease-causing

variants in the RPGR gene. MGT009 consists of three phases: dose-escalation, dose-confirmation, and dose-expansion. Each

patient was treated with subretinal delivery of AAV-RPGR in the eye that was more affected at baseline. The patient's other

eye served as an untreated control. In dose-escalation (n=10), adults were administered low, intermediate, or high dose AAV-RPGR.

The primary endpoint was safety. Visual function was assessed at baseline, three, six, nine and 12 months with Octopus 900 full-field

static perimetry and mesopic fundus-guided microperimetry (MP); mean retinal sensitivity, visual field modeling and analysis (VFMA;

Hill-of-vision volumetric measure), and pointwise comparisons were examined.

X-Linked Retinitis Pigmentosa (XLRP)

is the most severe form of retinitis pigmentosa (RP), a group of inherited retinal diseases characterized by progressive retinal

degeneration and vision loss. In XLRP, both rods and cones function poorly, leading to degeneration of the retina and total blindness.

The most frequent cause of XLRP is disease-causing variants in the RPGR gene, accounting for more than 70% of cases of