Successful treatment of tocilizumab-resistant large vessel pulmonary arteritis with infliximab.

Pulmonary hypertension associated with large vessel pulmonary arteritis (LVPA) has been reported in the course of Takayasu arteritis (TAK). Biologic therapies targeting inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin-6, have recently been successful to treat refractory TAK. Infliximab (IFX), an anti-TNF-α antibody and tocilizumab (TCZ), an anti-IL-6 receptor antibody may have similar efficacy and safety profile in the treatment of TAK. However, some cases are refractory to TNF inhibitors but respond to TCZ, and vice versa. Here, we report a severe case of LVPA, who was successfully treated with IFX but was refractory to TCZ and presented a discrepancy between serum C-reactive protein levels and fluorodeoxyglucose vascular positivity. This case would indicate heterogeneity of pathogenic mechanisms in LVPA and TAK.