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 absorption * AST \> 1.5 x ULN, ALT\>1.5 x ULN and Bilirubin \> 1.5 x ULN * ≥ Grade 2 proteinuria, creatinine \>1.5x ULN or GFR \<45 ml/min * Other investigational therapy received within 8 weeks prior to screening visit * Pregnant women or women who are breast feeding or of child bearing potential not using a highly effective method of birth control for at least one month prior to enrollment1 * Sexually active males not committing to birth control during the course of the study (except if their partner is not of childbearing potential) * Conditions that may affect the patient's ability to participate in this trial, e.g. known or suspected active alcohol or drug abuse * Inherited predisposition to bleeding or thrombosis, INR \>2, PT and PTT \>1.5x ULN * History of bleeding disorders or thrombotic events, e.g. hemorrhagic or thrombotic events within 12 months, clinically significant or tumor-related hemoptysis, active gastrointestinal bleeding or ulcers or major injuries or surgery * ANC \< 1.5 K/mcL, Platelets \< 100 K/mcL, Hemoglobin \< 9.0 g/dl * Concomitant treatment with any of the following drugs: azathioprine, cyclophosphamide, cyclosporine, pirfenidone, full dose anticoagulation (vitamin K antagonists, dabigatran, heparin, etc.), fibrinolysis and high dose anti-platelet therapy (ex. Plavix 150mg)\^2 Myocardial infarction or unstable angina within 6 or 1 month of starting nintedanib treatment, respectively * Known inherited predisposition to thrombosis * Patient with a history of a thrombotic event within 12 months of starting nintedanib treatment * Known predisposition to bleeding * Patients with severe hepatic impairment * History of a gastrointestinal perforation