MeiraGTx : AQP1 3 year data presentation 4162026

Published: 2026-04-16 09:40:10 ET MGTX

Published on 04/16/2026 at 09:40 am EDT

April 16, 2026

Introduction: Zandy Forbes, PhD. President C CEO MeiraGTx

Persistent Radiation Induced Xerostomia (RIX) is a severe, devastating, untreatable lifelong condition

Etiology of persistent RIX following radiation for Head and Neck Cancer

Mechanism of Action of AAV-AQP1

Phase 1 endpoints and data summary

AQUAx Phase 1 Study Data: Zandy Forbes, PhD President C CEO MeiraGTx

Phase 1 AQUAx 12-month data recap

Phase 1 AQUAx 3-year data showing robust 3-year durability and intra-patient consistency

Study Investigator discussion of disease burden, patient experience, and treatment administration

David Owens, MBCHB, FRCS, MPHIL, PGDME, FFST(Ed) (University Hospital of Wales)

Michael Brennan, DDS, MHS (Wake Forest University School of Medicine)

AAV-hAQP1 Commercial Opportunity: Zandy Forbes, PhD President C CEO MeiraGTx

Clinician Response to Durability demonstrated in 3-year data

Global and US market

Payor response to Durability Data

Market Concentration in the US

Question and Answer Session

Patient experience and disease burden: How bad is RIX really? Very bad indeed.

Persistent, late, RIX is a severe, untreatable, lifelong condition with devastating consequences for >30% of survivors of head and neck cancer.

Extreme persistent dry mouth, inability to swallow or chew, loss of sense of taste

Major diet restrictions, ongoing weight loss, need for invasive tube feeding

Oral health complications and frequent oral infections, sores and persistent pain.

Uncontrolled dental caries, accelerated loss of dentition requiring major reconstruction

Impaired speech, difficulty sleeping, inability to exercise as faster breathing may

lead to choking

Social isolation and refusal to interact with others.

Poor nutrition, lack of sleep, inability to exercise, continual pain, loss of social interaction have a significant, life-changing impact and may lead to frailty and premature death

"… People can't have a normal life. They go around with these sprays to moisturize the mouth … when they wake up in the morning and try to open their mouth, the skin tears and they have mouth ulcers…" Medical Oncologist, AMC (IT)

"It was like I had paper cut my tongue 100 times and then you suck on a lemon." JANET

"If I start choking, I can't get the food back out of my mouth which is really terrifying." CARRIE

Etiology of Persistent RIX and Population Size

Persistent RIX is the most frequent and severe consequence of curative radiation treatment for head s neck cancer

Almost all patients treated with radiation for HCN cancer experience acute xerostomia at the time of radiation

In 60%-70% of patients, acute radiation induced xerostomia resolves or becomes manageable by 12 to 18 months after radiation

However, in ~ 30%-40% of patients xerostomia does not resolve even 2 years after radiation

85% of these patients do not respond to any available therapy

Persistent RIX is a lifelong condition that only gets worse with time, with no effective therapies

Persistent RIX following treatment for HsN cancer is a large population and a completely unmet need:

In the US: there are 165k prevalent patients and >20k incidents per year

Globally (US, EU, Japan) there are 435k prevalent patients and 48k incidents per year

A large, commercial opportunity of up to $3.8bl annual sales globally and ~ $2bl in US

Salivary glands are particularly vulnerable to radiation

Damage to salivary glands during radiation leads to acute xerostomia in almost all patients

Over 12-18 months, damaged glands may remodel, saliva flow restored and xerostomia alleviated or becomes manageable (60%-70%).

In 30-40% of patients the damage to salivary glands is irreversible, the glands fail to recover and xerostomia persists for life.

AAV-hAQP1 is instilled into the duct of damaged glands and transduces the remaining gland epithelium with the gene encoding the Aquaporin 1 (AQP1), a non-polarized water channel.

Expression of the AQP1 makes the epithelium permeable to water and allows water to flow down the concentration gradient into the salivary duct and into the mouth

AAV-AQP1 Delivery Procedure:

Small dose delivered locally directly to salivary gland

Simple in-office procedure

No general anesthesia or pain

One-time therapy

Low cost of goods

Phase1 (n=24): Transformative Clinical Improvements in Xerostomia PRO (XQ) as well as Objective Saliva Flow (UWSFR) Endpoints

Xerostomia Clinical Definition:

Xerostomia is a purely patient reported condition

The level of xerostomia symptoms is not correlated to the absolute amount of saliva produced by an individual (ASCO Guidelines)

However, xerostomia is the result of too little saliva available to wet the mouth and retain normal oral health and function.

Xerostomia Endpoints:

Xerostomia Questionnaire (XQ) is the standard patient-reported measure of xerostomia

Unstimulated Whole Saliva Flow Rate (UWSFR) is an objective measure of the change in salivary function

Phase 1 Clinical Data:

Compelling 12 month data:

XQ score 12-month data demonstrate "unprecedented" and "transformative" improvements in xerostomia

USWFR also showed large increases in water flow into the mouth - the objective measure of AAV-AQP1 MOA

Durability of effect : Phase 1 study shows these transformative improvements in XQ and UWSFR are maintained out to 3 years

AAV-AQP1 has the potential to be a disease modifying therapy with durable, transformative benefits for this otherwise severe, lifelong, untreatable condition

Granted Breakthrough Therapy designation in addition to RMAT and ODD

Open-label, multi-center, dose-escalation study (4 sites, US/Canada)

One-time administration of AAV-AQP1 to one (unilateral) or both (bilateral) parotid glands

Four dose-escalating cohorts with 3 participants per cohort (n=12 for unilaterally treated and n=12 for bilaterally treated)

All participants are followed for 1-year post-treatment and then invited to enroll in a long-term follow-up study for a total of 5 years

Primary endpoint

Cohort

Dose

Unilateral treatment

1 × 1011 vg/gland

3 × 1011 vg/gland

1 × 1012 vg/gland

3 × 1012 vg/gland

Bilateral treatment

3 × 1010 vg/gland

1 × 1011 vg/gland

3 × 1011 vg/gland

1 x 1012 vg/gland

Safety

Secondary endpoint

Patient reported measures of

xerostomia symptoms

Xerostomia Questionnaire (XQ)

MD Anderson Symptom Inventory - Head and Neck

Global Rate of Change Questionnaire (GRCQ)

Unstimulated whole saliva flow rate

AAV2-hAQP1 was generally safe and well-tolerated at all doses tested

No treatment-related serious adverse events

No dose-limiting toxicities

No participant discontinued from the study

6 mild, treatment-emergent treatment-related adverse events (TEAEs). All resolved without sequelae.

Average change in XQ score

Bilateral Unilateral Mean

8 symptom-specific xerostomia PRO answered by patients with a total

maximum score of 80 points (higher is worse)

Mean change from baseline in XQ total score

An improvement (decrease) of ≥8 points is considered clinically meaningful

An improvement of ≥10 points is considered transformative

Transformative improvement: Average XQ score improved by 17 points (39.5%) at Month 12

Bilaterally-treated participants reported greater improvement than those treated unilaterally, 21 points vs 13 points, with 75% of bilaterally-treated patients reporting transformative (≥10 point) improvement at Month12

Responses were durable up to 3 years (latest visit)

1. Eisbruch A et al. Xerostomia and its predictors following parotid-sparing irradiation of head-and-neck cancer. Int J Radiat Oncol Biol Phys. 2001 Jul 1;50(3):695-704. 2. Jabbari S et al. Matched Case-Control Study of Quality of Life and Xerostomia after Intensity-Modulated Radiotherapy or Standard Radiotherapy for Head-and-Neck Cancer: Initial Report. Int. J. Radiat. Oncol. Biol. Phys. 2005;63:725-731.

Average percent change from baseline

120%

100%

112.5%

80%

86.5%

74.5%

60%

62.7%

54.5%

56.2%

40%

20%

7.3%

-20%

-13.0%

-40%

Months post treatment

Average % change from baseline

At Month 12, the Unstimulated Whole Saliva Flow Rate increased by 112.5% from baseline

Participant

Cohort

Dose per gland

Visit of Biopsy

Copy #/ng DNA

Copy #/Cell

AAV001

1E10

18 Months

160

0.96

AAV005

1E10

24 Months

122

0.73

AAV002

3E10

18 Months

236

1.4

AAV019

1E11

24 Months

5393

AAV020

3E11

30 Months

AAV021

3E11

12 Months

87390

524

AAV031

6E11

12 Months

7313

Core needle biopsies were obtained in 7 participants who enrolled in a NIH Phase 1 study of AAV2-hAQP1 (MGT001).

6/7 biopsies showed AAV2-hAQP1 genomes 12-30 months post-treatment

There was a trend of increasing copy number of vector

genomes with increasing viral vector dose

The image on the right shows a core needle biopsy from a participant in the NIH Phase 1 study

AQP1 protein expression was observed in parotid gland cells at

24 months post-treatment

Acinar cells in this section express AQP1 (shown in white), whereas they normally express only AQP5 - here shown in green

Levels of AQP1 protein in transduced acinar cells appear similar to the endogenous levels seen in non-parotid endothelial cells

Phase 1 data out to 3 years on all cohorts

Average change in XQ score from baseline

The transformative improvement in the XQ PRO observed in Month 12 were maintained through Month 36

Bilaterally-treated participants reported greater improvement than those treated unilaterally

Visit

Baseline

Day 2

Day 8

Day 15

Day 30

Day 60

Day G0

Day 180

Month 12

Month 18

Month 24

Month 36

N_Overall

N_Bilateral

N_Unilateral

Waterfall Plots of individual subject XQ scores at 12 months: Bilateral and Unilateral: Absolute change and Percentage change

Absolute Change from Baseline

Percent Change from Baseline

Individual patient data demonstrate durable clinical response over 3 years

Bilateral cohort: Change from baseline (XQ)

Unilateral cohort: Change from baseline (XQ)

Robust Clinical Response: almost all patients experienced a significant improvement in xerostomia symptoms, with

some patients reporting complete resolution of their xerostomia symptoms

Sustained Long-Term Durability: most subjects maintained or further improved their response over the three-year

follow-up period

Waterfall Plot of individual subject XQ score at each visit over 36 months showing the consistency of individual patient responses

Individual Patient XQ score at each visit out to 36 months: the graphs shows the XQ scores for each patient from left to right in the order of magnitude of XQ in the 12 month waterfall plot grouped together at 12,18, 24 and 36 months and illustrates the consistency in XQ response for each patient over 3 years.

Those patients with the the strongest response at 12 months tended to maintain the strongest responses over 36 months, and those with the worst scores at 12 months tended to have the worst scores throughout the study to 36 months.

Waterfall Plots of individual subject XQ scores at 12 months: Bilateral and Unilateral Combined

Individual Patient XQ score at each visit out to 36 months: the graphs shows the XQ scores for each patient grouped together at 12,18, 24 and 36 months and illustrates the consistency in XQ response for each patient over 3 years.