In patients with inflammatory arthritis (RA, psoriatic arthritis) and a history of MGUS are there any concerns regarding use of biologics?

There is no absolute contraindication to any particular biologic used to manage active RA in a patient with MGUS. The literature does point out a small potential risk associated with tocilizumab in terms of development of myeloma influenced by the IL-6 pathway (and I would tend to extend that potential concern to sarilumab) -- but this was based on a case control study, and absolute numbers of events were not large. (Calip et al., PMID 31997371)

I might consider that data in RA, given the number of other potential agents available to us at this time. On the flip side, if the patient had PMR or GCA, I would absolutely treat them with either agent over longer-term higher to moderate dose glucocorticoids.