Genetic Markers of Methotrexate Treatment Failure in Psoriasis.

Background: Pharmacogenetic markers associated with the need to switch patients from methotrexate (MTX) to biologic agents in moderate-to-severe psoriasis remain insufficiently studied. The pharmacokinetics of MTX depend on the individual characteristics of the patient, as well as on the function of specific transporters and enzymes involved in its absorption, distribution, metabolism, and elimination; therefore, polymorphisms in genes encoding these proteins may be considered pharmacogenetic predictors of MTX intolerance or insufficient efficacy. This study aimed to investigate genetic variants associated with MTX intolerance or insufficient efficacy leading to therapy switch. Methods: A total of 80 patients with moderate-to-severe psoriasis were included: 43 who required switching from MTX to biologics and 37 who continued MTX therapy. Twelve polymorphisms in transporter and metabolism-related genes (ABCB1 (rs1045642), MTHFR (rs1801133), ABCB1 (rs1128503), ABCC2 (rs3740066), ABCC2 (rs717620), ABCG2 (rs2231137), GSTP1 (rs1695), SLC19A1 (rs1051266), COL18A1 (rs9977268), SLCO1B1 (rs2306283), SLCO1B1 (rs4149056), and ABCB1 (rs2229109)) were analyzed using next-generation sequencing. Results: Significant differences in genotype frequencies were observed for SLC19A1 rs1051266 (p = 0.03) and COL18A1 rs9977268 (p = 0.02). Carriers of the T allele in both genes were more frequent among patients requiring biologic therapy, suggesting a possible association with MTX intolerance or reduced efficacy. Conclusions: The study revealed an association between polymorphisms in the SLC19A1 rs1051266 and COL18A1 rs9977268 genes and the need to switch from MTX to biologic therapy in patients with moderate-to-severe psoriasis. These findings suggest that carriers of the C allele in these genes may have an increased risk of methotrexate intolerance.