Assessment of the influence of Fc‐γ receptor polymorphisms on biologics' pharmacokinetics in Tunisian rheumatoid arthritis patients

Aims This study aims to determine whether a modification in Fc‐γ receptors' (FcgRs) affinity to Fc portion, caused by single nucleotide polymorphisms such as rs1801274‐R131H FcgRIIa, rs396991‐F158V FcgRIIIa and NA1/NA2‐FcgRIIIb, might impact clearance of therapeutic monoclonal antibodies and thus serum drug levels and the development of anti‐drug antibodies. Methods A cross sectional, multicentral and noninterventional study was conducted in Tunisian RA patients treated with rituximab (RTX), etanercept (ETA), infliximab (IFX) and adalimumab (ADL). Serum drug level (SDL) of the different biologics and ADA against them were measured. All patients were genotyped for the 3 FcgR single nucleotide polymorphisms. Results A total of 81 patients were included: 47 were under tumour necrosis factor inhibitors (18 ETA, 13 ADL and 16 IFX), and 34 were under RTX. Regardless of the type of biotherapy, SDL was in therapeutic range, in 35 patients (43.2%), of whom only 1 was treated with RTX. Fourteen patients (22.2%) developed ADA, but none of the patients treated with ETA had detectable ADA levels. There was no association between SDL positivity and FcgR polymorphisms. However, the high affinity FcgR2A 131 H/H receptor was statistically more prevalent in patients with detectable ADA treated with ADL, IFX and RTX (P = .018). The same result was obtained in the monoclonal antibody tumour necrosis factor inhibitor subgroup (n = 29, P = .022) as well as in patients treated only with IFX (n = 16, P = .029). Conclusion Our work supports the hypothesis of an impact of FcgR single nucleotide polymorphisms on biologics' immunogenicity, particularly FcgR R131H polymorphism, but further studies with larger cohorts need to be undertaken to confirm these results.