In this study, we conducted a multicenter, double-blind, placebo-controlled clinical trial of PC-SOD (midismase) to investigate the safety and effectiveness of this agent in patients with advanced IIPs diagnosed as either IPF or corticosteroid-resistant fibrotic nonspecific interstitial pneumonia (srf-NSIP). The gene discussed is SOD1; the disease is idiopathic pulmonary fibrosis.