Abstract Background/Aims The MYOPROSP (NCT02468895) study is a prospective, multicentre observational cohort that recruited adult patients with idiopathic inflammatory myopathies (IIM) from 23 UK centres between 2016 and 2020. We previously have reported that, despite longer disease duration and more prior treatment failures, refractory adult IIM patients treated with rituximab in this cohort achieved a significantly higher Total Improvement Score (TIS) response rate than those on conventional immunosuppressants. However, 29.6% of refractory cases still responded poorly to rituximab, and clinically validated biomarkers that can predict response to rituximab remain lacking. We aim to investigate proteome and inflammatory transcriptional profile of refractory IIMs in response to rituximab treatment. Methods We conducted a translational extension of the above cohort study, leveraging prospectively collected PAXgene RNA (12) and serum samples (13) from the rituximab-treated cases to profile inflammatory gene expression and multiplex proteomic signatures in a paired pre- and post-treatment analysis. Male and female patients from diverse ethnic background and with diagnosis of anti-synthetase syndrome, dermatomyositis, immune-mediated necrotising myopathy and overlap myositis participated in the study. A 32-gene custom inflammation panel was assayed on the NanoString nCounter platform and the resulting transcript counts were analysed with nSolver 4.0. Inflammation-related proteins were quantified with the NULISAseq™ Inflammation Panel 250. Significantly differentially regulated proteins (p 0.05) were selected for protein network analysis and gene ontology pathways. Results Differential gene transcription revealed that MX1, IFI6, IFI44L, ISG15, SOCS1, TNF, IL12-A and PD-L1 were significantly elevated in refractory myositis patients when pre- and post-rituximab-treated patient samples compared with healthy controls. Among inflammatory proteins, IL6, TNFRSF13 and IL36 were identified to be differentially regulated after rituximab treatment. Comparing rituximab responders to non-responders, a distinct set of proteins including IL6ST, IFNW1, IL17A, TNFRSF1, IL36B, and TNSF8, showed significant differential regulation. Gene ontology analysis demonstrated association of these markers with immune response, adaptive immune response, T cell activation, cytokine stimulus and cytokine mediated signalling pathways. Conclusion Refractory myositis patients exhibit up-regulation of the type I interferon pathway, and proteome analysis identified differentially expressed markers, which show promise for predicting rituximab treatment outcome. Further investigations are warranted with larger sample size. Disclosure S.S. Rane: None. X. Lyu: None. P. Gordon: Grants/research support; Alexion (PI at King’s College Hospital for ALXN1210-DM-310), Argenx (PI at King’s College Hospital for ARGX-113-2007 and ARGX-113-2011), Bristol-Myers Squibb (Chief investigator for UK for POETYK SLE), Celltrion Healthcare (Funded to attend EULAR convergence in 2023), Eli Lilly (PI at King’s College Hospital for MOJAK), Galapagos (Advisor or Review Panel Member, Consultant, Chief investigator in UK. H. Gunawardena: None. N. McHugh: None. A. Prabu: None. P. Lanyon: Other; AstraZeneca (Advisor or Review Panel Member), CSL Vifor (Grant/Research Support, Speaker/Honoraria), CSL Vifor (Grant/Research Support, Speaker/Honoraria). J. Miller: None. V. Ong: None. A. Isaacs: None. P. New: None. C. Yee: None. C. Cotton: None. P. Kiely: None. E. Stathopoulou: None. J. Taylor: None. R. Jeffery: None. A. Bharadwaj: None. J.B. Lilleker: None. J.A. Lamb: Grants/research support; Eli Lilly (Grant/Research Support). H. Chinoy: Grants/research support; Eli Lilly (Grant/Research Support). Other; AstraZeneca, Janssen, Pfizer (Advisor or Review Panel Member).
Rane et al. (Wed,) studied this question.