Checkpoint inhibitor-related pneumonitis (CIP）is a common fatal immune-related adverse event of PD-1/PD-L1 inhibitors. Some CIP patients have poor effect on hormone therapy, and the remission time of CIP varies greatly. Antifibrotic drugs may be effective in patients with CIP.

Pirfenidone can inhibit the occurrence and development of pulmonary fibrosis, reduce pulmonary exudation by inhibiting VEGF and promote pulmonary recovery. In our study, subjects with checkpoint inhibitor-related pneumonitis receive pirfenidone plus methylprednisolone or methylprednisolone.

Inclusion Criteria:

1. Male or female who is 18 to 75 years old.
2. Malignant tumors proved by pathology.
3. The subject has received at least one course of immune checkpoint inhibitor treatment.
4. The subject developed grade 3-4 CIP.
5. Take proper contraceptive measures.
6. Appropriate organ system function.
7. Subjects voluntarily participate in this study and sign the informed consent.

Exclusion Criteria:

1. Previous treatment with pirfenidone.
2. Clinically significant hemoptysis occurred within 3 months before enrollment (hemoptysis greater than 50ml per day); Or significant clinical bleeding symptoms or clear bleeding tendency, such as gastrointestinal bleeding, hemorrhagic gastric ulcer, baseline fecal occult blood + + or above, or macrovasculitis.
3. Arteriovenous thrombosis events occurred within 12 months before enrollment, such as cerebrovascular accident, deep venous thrombosis and pulmonary embolism.
4. Abdominal surgery was performed 4 weeks before enrollment, or there was a history of hollow organ perforation.
5. Use nintedanib, cyclophosphamide or cyclosporin within 56 days before enrollment.
6. Suffering from active pulmonary tuberculosis.
7. Patients with mental illness and poor compliance.
8. Sperm / egg donors within 6 months.
9. Lactating women.
10. Persons allergic to pirfenidone.
11. In the investigator's judgment, there are other factors that may have led to the termination of the study.

No plan.