Study to Evaluate the Efficacy and Safety of Nintedanib (BIBF 1120) + Prednisone Taper in Patients With Radiation Pneumonitis

Inclusion Criteria: * Histologically/cytologically proven primary thoracic or breast malignancy, lymphoma or lung metastases (which are not required to be biopsy-proven) treated with definitive intent at MSK * Prior treatment with thoracic radiotherapy completed \>4 weeks and ≤ 9 months prior to enrollment * Radiographic evidence of radiation pneumonitis on a CT scan of the chest with or without contrast * Newly diagnosed clinical grade 2 or higher radiation pneumonitis according to CTCAE version 4.0 criteria * Age≥18 years * KPS \> 70% * Reduction of any acute toxicity from radiation treatment to grade 1 * Written informed consent signed prior to entry into the study Exclusion Criteria: * Current oral steroid use \> 4 weeks prior to registration * Ongoing treatment with radiotherapy to thorax, cytotoxic or biological therapies for this malignancy, except the following therapies which are permitted: Pembrolizumab, Nivolumab, Afatinib and all hormonal therapies. * Mean esophageal radiation dose \>45 Gy * Diagnosis of diffuse radiation pneumonitis * Untreated or symptomatic brain metastases or leptomeningeal disease * Liver metastases * Other active malignancies requiring oncologic treatment (Note: non-melanoma skin cancer, superficial bladder cancer etc. are eligible) * Radiographic evidence of cavitary or necrotic tumor and local invasion of major blood vessels * Active chronic Hepatitis C and/or B infection * Gastrointestinal disorders that would interfere with drug absor…