Currently, it is manufactured and sponsored for use as an orphan drug and for clinical studies by the Japanese company Euro Nippon Kayaku.

The European Commission assigned orphan drug status to Gusperimus in 2001 for the treatment of granulomatosis with polyangiitis, a serious form of vasculitis frequently associated with permanent disability and/or fatal outcome.

There have been many cases of patients resistant to all forms of usual treatment responding very well to Gusperimus.

The following side-effects have been noticed so far: It is not known if therapy with gusperimus may increase the risk of malignant diseases (lymphoma, leukemia, solid tumors), as is the case with other highly potent immunosuppressant agents such as ciclosporin or tacrolimus.

It is recommended to obtain complete WBC (White Blood Cell) counts during and after each cycle frequently.