ABBV-RGX-314 well tolerated with sustained anti-VEGF protein expression in wet AMD
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Key takeaways:
- The phase 1/2a study showed that gene therapy can be used to provide sustained delivery of a therapeutic protein.
- Higher doses of ABBV-RGX-314 demonstrated exudation control and vision maintenance.
Subretinal delivery of ABBV-RGX-314 gene therapy demonstrated safety and sustained anti-VEGF protein expression at higher doses in patients with neovascular age-related macular degeneration, according to a study.
“Currently, many patients with nAMD require frequent intraocular injections of an anti-VEGF protein to control exudation and maintain vision, and observational studies have shown that many patients do not get the frequency of injections needed and therefore lose vision,” Peter A. Campochiaro, MD, lead author of the study published in The Lancet, told Healio. “Treatments like ABBV-RGX-314 that control exudation with less burden could improve visual outcomes in nAMD patients in clinical practice.”
The primary outcome of the phase 1/2a open-label, multiple-cohort, multicenter, dose-escalation study was the safety of the adeno-associated virus serotype 8 vector up to week 26.
The study, which took place at eight U.S. sites, included 42 subjects with macular neovascularization secondary to neovascular AMD. The original study design had three dose cohorts of six subjects randomly assigned to 3×10, 1×10¹ or 6×10¹ genome copies per eye. Two additional cohorts of 12 subjects who were given 1.6×10¹¹ or 2.5×10¹¹ genome copies per eye were added later. Subjects were evaluated 1 day and 1 week after administration of ABBV-RGX-314 (Regenxbio, AbbVie) and then monthly for 2 years.
“The amount of anti-VEGF protein produced in each patient was determined by measuring its concentration in the aqueous at several time points after injection, which is critical for interpreting results,” Campochiaro said.
Overall, subretinal delivery of the gene therapy was well tolerated, with no clinically recognized immune responses reported. Twenty serious adverse events occurred in 13 subjects, with one possibly related to ABBV-RGX-314, a subject who experienced severe vision reduction at 12 months related to pigmentary changes in the macula after an injection of 2.5×10¹¹ genome copies per eye.
According to Campochiaro, doses of 6×10¹ genome copies or higher demonstrated “sustained production of the anti-VEGF protein, control of exudation and maintenance of vision in many patients,” while lower doses showed little to no anti-VEGF protein production and no beneficial effects.
“The most important message is that gene therapy can be used to provide sustained delivery of a therapeutic protein,” he said. “There are two ongoing phase 3 trials, which, if successful, could lead to regulatory approval of ABBV-RGX-314, making it available for use in clinical practice.”
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