HLA-DRB1 and rheumatoid arthritis: The analysis of polymorphic variant combinations revealed the maximal predictive value according to the ACR20 at week 24 of olokizumab therapy for the combination of alleles HLA-DRB1*04 and HLA-B*27 together with alleles (genotypes) of non-HLA genes and such clinical parameters such as the age of a patient, RA severity, and duration at the time of inclusion in the study.