3. Meet two or more of the following criteria (must include 1) 1. Serum KL-6 above the upper normal limit 2. Presence of dyspnea on exertion (grade 2 on the Magnitude of Task component of the Mahler Modified Dyspnea Index 3. PaO2 of less than 80 mmHg while breathing ambient air at rest, not accompanied by abnormal increase of PaCO2 4. Vital capacity < 80% predicted, or diffusing capacity for carbon monoxide < 65% predicted 5. Meet at least one of the following condition over the 12-week period (84 days) prior to the initiation of the study drug