Fatty acid desaturase insertion-deletion polymorphism rs66698963 predicts colorectal polyp prevention by the n-3 fatty acid eicosapentaenoic acid: A secondary analysis of the seAFOod polyp prevention trial – PubMed

Background:

A fatty acid desaturase (FADS) insertion-deletion (Indel) polymorphism (rs66698963) influences expression of FADS1, which controls synthesis of n-6 highly unsaturated fatty acid (HUFA) arachidonic acid (AA). The anti-inflammatory activity of the n-3 HUFA eicosapentaenoic acid (EPA) may be explained by competition with AA for pro-inflammatory lipid mediator synthesis. A precision medicine approach based on stratification by FADS Indel genotype could identify individuals, who benefit from greatest disease risk reduction by n-3 HUFAs.

Objective:

We tested the hypothesis that the FADS insertion (I) allele predicts colorectal polyp risk reduction in a secondary analysis of the randomized, placebo-controlled, 2 x 2 factorial seAFOod polyp prevention trial of EPA 2000 mg daily and aspirin 300 mg daily for 12 months (ISRCTN05926847).

Methods:

Participant Indel genotype was determined by PCR blind to trial outcomes. Colorectal polyp outcomes were included in negative binomial (polyp number) and logistic (polyp detection rate [PDR; percentage with one or more polyps]) regression models comparing each active intervention versus placebo. Presence of at least one Indel I allele and an interaction term (I allele x active intervention) were co-variates.

Results:

In 528 participants with colonoscopy and FADS Indel data, EPA use irrespective of Indel genotype, was not associated with reduced colorectal polyp number (incidence rate ratio [IRR] 0.92, 95% confidence interval 0.74, 1.16), mirroring original seAFOod trial analysis. However, presence of at least one I allele identified EPA users with a significant reduction in colorectal polyp number (IRR 0.50 [0.28, 0.90]), unlike aspirin, for which there was no interaction. Similar findings were obtained for the PDR.

Conclusions:

The FADS Indel I allele identified individuals, who displayed colorectal polyp prevention by EPA with a similar effect size to aspirin. Assessment of rs66698963 as a biomarker of therapeutic response to n-3 HUFAs in other populations and healthcare settings is warranted.

Trial registration:

The seAFOod polyp prevention trial and STOP-ADENOMA study are registered with https://www.isrctn.com as ISRCTN05926847.