Abstract Drug-induced pneumonitis (DRP) due to targeted therapies for cancer treatment are growing increasingly common with recent pharmacological advances. While patients may experience benefits in terms of their cancer prognosis, they may often face significant debility due to the interval development of pneumonitis complicating their clinical course. Here, we present such a case of a 54-year-old male who developed hypoxic respiratory failure secondary to fam-trastuzumab induced pneumonitis. The patient was first diagnosed with male breast cancer with metastasis to bones and lungs that was ER 90%, PR 51% positive and Her-2 LOW. However, despite four different chemotherapy modalities, patient had PET scan findings of progressive disease in the lungs and bones. As a result, patient was started on fam-trastuzumab as fifth line therapy. Within a month, patient started to develop worsening dyspnea and increasing oxygen requirements. Initially, large bilateral pleural effusions were thought to be the cause. Despite PleurX catheter placement, confirmed adequate daily drainage and completion of two courses of antibiotics, patient had worsening dyspnea requiring hospital admission. The inpatient pulmonology team conducted non-invasive microbiological workup which was unremarkable. CT findings showed progression in pulmonary infiltrates suggestive of multifocal pneumonia versus organizing pneumonia. Inspite of empiric antibiotic coverage, patient only started to show clinical improvement after starting IV Solumedrol 40 mg Q8H which was tapered as oxygen requirements improved. Once at baseline, patient was discharged with a prolonged steroid taper over the course of 8 weeks, along with Bactrim for Pneumocystis Jirovecii pneumonia prophylaxis. Unfortunately, patient wished to transition to hospice after 4 rounds of Enhertu treatment due to poor quality of life from respiratory compromise. It was found that DRP occured in 15.4% patients receiving fam-trastuzumab therapy for Her2-positive breast cancer. As Her2 is expressed by lung cells, the lungs are a common target. DRP is a diagnosis of exclusion and early identification is paramount. Timing of drug exposure to symptom onset, clinical, microbiological and radiological workup is necessary to come to this diagnosis. Patterns of lung injury in CT imaging mimic those of ILD and can vary widely from case to case. Common patterns seen include organizing pneumonia (as seen in our patient), nonspecific interstitial pneumonia, hypersensitivity pneumonitis and acute interstitial pneumonia pattern. Sometimes these patterns intermix, and there may be a lack of a distinct picture. Severity of symptoms influence whether dose reduction, drug holiday or complete cessation of such agents is the best modality for treatment. This abstract is funded by: None
Kalvapudi et al. (Fri,) studied this question.