TNF and arthritic joint disease: To define whether the synovial expression of AXL and MERTK varies according to the disease stage and is modulated by treatment exposure, we compared AXL and MERTK RNA expression from the early arthritis cohort to a cohort of late, difficult-to-treat (D2T) RA patients, characterised by an inadequate response (ir) to csDMARDs and at least one TNFα inhibitor (TNFα-ir) prior to randomisation to a second-line biologic agent (either rituximab -RTX- or tocilizumab -TOC) in the R4RA biopsy-driven randomised clinical trial, described in refs. 15,16; data available at https://r4ra.hpc.qmul.ac.uk/.