As a treatment for inflammatory myopathies such as spontaneous inclusion body myositis (sIBM), phase II and III trials of BYM-338 (bimagrumab, Norvartis), an anti-ActRIIB-antibody in sIBM failed to show positive long-term functional effects [168,169,170]. The gene discussed is ACVR2B; the disease is inclusion body myositis.