Imatinib could be a new strategy for pulmonary hypertension caused by pulmonary tumor thrombotic microangiopathy in metastatic breast cancer

INTRODUCTION: Pulmonary tumor thrombotic microangiopathy (PTTM) is rare, cancer-related pulmonary complication leading to hypoxia, pulmonary hypertension, and heart failure. The standard treatment for PTTM is not established. However, imatinib, a tyrosine kinase inhibitor of the PDGF receptor, may cause regression of pulmonary hypertension and pulmonary artery remodeling in PTTM. CASE DESCRIPTIONS: We report two cases of PTTM who received an anti-PDGF agent of imatinib for PTTM developed during chemotherapy for metastatic breast cancer. Case 1: 61-year-old woman who underwent resection of the left breast and axillary lymph node dissection and received adjuvant chemotherapy (CAF followed by docetaxel), then endocrine therapy for 5 years. Twelve years after surgery, multiple bone and mediastinal lymph node metastases occurred. She was under treatment with eribulin for one year but admitted because of rapid progressing dyspnea. Case 2: 45-year-old woman with metastatic breast cancer in multiple bones was under treatment for 5 years. Receiving capecitabine, she suffered from dyspnea for 2 months, she was admitted to our hospital with diagnosis of severe hypoxia. In both cases, the wedged pulmonary arterial blood cell sampling revealed cytologically malignant cells which confirmed the diagnosis of PTTM. They were treated with imatinib, which alleviated pulmonary hypertension. However, they died due to progression of metastatic breast cancer. DISCUSSION AND EVALUATION: Single use of imatinib did not showed sufficient efficacy. It is necessary to conduct a well-designed clinical trial using chemotherapies combined with imatinib for PTTM. CONCLUSIONS: Imatinib, which alleviated pulmonary hypertension, could be a new strategy for pulmonary tumor thrombotic microangiopathy in patient with metastatic breast cancer.