AMD Pharmacogenetics

Optimizing Outcomes

Pharmacogenetics is the science of how genetic variation affects an individual’s response to treatment. Pharmacogenetics is used to optimize therapeutic outcomes, determine the appropriate dose for a patient, and avoid harmful effects. For example, abacavir is an antiretroviral treatment for HIV, but it causes severe side-effects in individuals who possess the HLA-B*5701 allele. Vemurafenib is an effective drug for melanoma, but only in individuals with V600 mutations in the BRAF gene. High-dose eye supplements may be used to prevent progression from intermediate to advanced AMD, and now also have pharmacogenetic indications to improve outcomes and minimize deleterious effects.

The Age-Related Eye Disease Study (AREDS) demonstrated that high-dose supplementation with antioxidants plus zinc reduced the risk of progression to Wet age-related macular degeneration (AMD) in patients with intermediate AMD in at least one eye [8]. In 2013, a pharmacogenetic analysis of the AREDS dataset showed that components of the AREDS formulation may be beneficial or harmful based on a patient’s genotype in the CFH and ARMS2 genes[9].

 

This was followed in 2015 by a direct observation of outcomes on 7 years of follow-up on AREDS study patients. The investigators compared actual AMD progression rates within these patients who received placebo, antioxidants, zinc, or the AREDS formulation. The benefit of the AREDS formulation was the result of a favorable response by some patients but an unfavorable responses in others.[5]

 

In 2016 an additional independent study also evaluated the role of genetic variants in modifying the relationship between supplementation and progression to advanced AMD among 4124 eyes (2317 subjects with a genetic specimen). The interaction between supplements and individual genotypes, were evaluated for their association with AMD progression. The study confirmed that some patients benefit and some do not for each of the treatments.[12]

 

The Vita Risk® pharmacogenetic analysis, now available alone or as part of the Macula Risk PGx test, supports this genotype-directed selection of eye supplements for patients with Intermediate Dry AMD to delay or prevent progression to Wet AMD.