Would you add abatacept to treat active inflammatory arthritis in a patient with history of RA-ILD who is already taking mycophenolate?

Although there are no controlled trials of abatacept in RA-ILD, the current literature suggests a stabilization of ILD in RA patients and is one of my principal go-to agents for this situation. A review paper from 2021 (Vicente-Rabaneda et al., PMID 33887489) indicated abatacept was associated with a 90% reduction in the relative risk of deterioration of ILD at 24 months of follow-up when compared to TNF inhibitors and non-biologic DMARDs.

I have added abatacept to mycophenolate without an excess of side effects in a small number of patients in our combined ILD/rheumatology clinic. Fernandez-Diaz et al., PMID 33779697 did look at safety and efficacy in RA-ILD patients on abatacept alone, combined with methotrexate, or combined with other csDMARDs and found no additional benefit to ILD by adding other agents but no excess side effects in the combined groups. The combined groups did demonstrate though, a lower corticosteroid requirement.

Mycophenolate was investigated as a potential therapeutic agent for RA many years ago but the trial was stopped due to inefficacy. RA-ILD patients will generally need something beyond mycophenolate for active joint disease and abatacept has the advantage of having benefit for both. 

Based on the data, it would make sense to add abatacept to an RA-ILD patient on mycophenolate and then see if mycophenolate could be tapered without worsening of the ILD or increase in corticosteroid dosing.