Interstitial pneumonitis associated with trastuzumab emtansine.

Trastuzumab emtansine is an antibody-drug conjugate that is effective in human epidermal growth factor receptor-2 expressing advanced breast cancer. Trastuzumab emtansine is generally well tolerated and grade 3-4 toxicities are rare. Pulmonary complications were rarely reported. Here we present a patient presenting with dyspnea after trastuzumab emtansine therapy and treated with a diagnosis of interstitial pneumonitis.