Off-label use of mycophenolate mofetil in the treatment of rare and complex rheumatic connective tissue diseases.

Objectives: We aimed to investigate the clinical off-label use of mycophenolate mofetil (MMF), including its safety and efficacy in patients with rare and complex rheumatic connective tissue diseases (rCTDs).
Methods: A survey was distributed across experts from ERN-ReCONNET reference centres in order to assess the experience with MMF off-label use. Patient-level data of patients with rCTDs under treatment with MMF was also collected for analysis of safety and efficacy.
Results: Twelve experts from eleven centres distributed throughout Europe (7 countries) answered the survey. The experience was concordant in that, despite of its off-label use, experts reported opting frequently for this therapeutic alternative with robust confidence on its efficacy and safety. The analysis of 108 patients with rCTDs under MMF revealed a good safety profile, as well as good clinical outcomes, especially for systemic lupus erythematosus and idiopathic inflammatory myopathies. The presence of interstitial lung disease was, as expected, associated with a worse clinical outcome despite use of MMF.
Conclusions: MMF is widely used in reference centres for rCTDs. Its safety profile and efficacy seem to be recognised by experts and demonstrated with patient-level analysis. While selected rCTDs will likely remain an off-label indication for MMF, robust data seem to support this therapy as an appropriate alternative for safely and effectively treating many manifestations of rCTDs.