- Adverum Biotechnologies said eye-disease patients treated with its gene therapy ADVM-022 experienced on average eyesight declines 24 weeks after treatment, although they saw improvements in other disease markers.
- The data come four months after rival Regenxbio released data from its more advanced gene therapy RGX-314, which showed patients' eyesight got better.
- Adverum shares tumbled 26% today, knocking more than $200 million from the company's valuation.
In the case of Adverum, the data came from a presentation at a meeting of the Retina Society in London, covering six patients with wet age-related macular degeneration (AMD) in the cohort treated with ADVM-022 in the Phase 1 OPTIC trial.
After 24 weeks, the patients saw their eyesight decline by two letters on the "best corrected visual acuity" scale. On the other hand, patients also experienced reversal of retinal thickening, which can distort vision, by 52.7 micrometers.
Regenxbio, which has tested its AMD gene therapy RGX-314 in 42 patients as of July 31, saw an improvement in BCVA of five letters in a six-patient cohort one year after treatment. That company is planning for a Phase 2b trial to begin late this year.
The picture for Adverum could change as trial investigators continue to monitor patients, or as the company increases the dose. Patients in this cohort of OPTIC were given 600 billion vector genomes per eye, 10 times the dose received by the Regenxbio patients in the cohort it has most recently reported.
Adverum said it will announce further developments in the OPTIC trial in the fourth quarter of 2019.
Eye disease is seen as a good target for gene therapy because the eye's immune-privileged status allows for lower dosing that what's required for gene therapies treating systemic disorders. The first gene therapy approved by the Food and Drug Administration, Luxturna (voretigene neparvovec), treated a rare form of blindness caused by mutation of the RPE65 gene.
The difference with AMD is that it is a comparatively common disease with existing treatments in the form of Lucentis (ranibizumab) and Eylea (aflibercept), which require periodic eye injections.
Justifying a one-time treatment that potentially could cost hundreds of thousands of dollars may be a challenge, especially since the wet AMD affects older people who will see fewer years of benefit when compared to the younger patients eligible for Luxturna.