Osimertinib

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An event is serious (based on the ICH definition) when the patient outcome is:

• * death

• * life-threatening

• * hospitalisation

• * disability

• * congenital anomaly

• * other medically important event

A 71-year-old woman developed pneumonitis and interstitial lung disease during treatment with osimertinib for lung cancer.

The woman, who had history of humerus fracture from metastatic lytic lesion was diagnosed with advanced stage non-small cell lung cancer. Further she was diagnosed with stage IV lung cancer and started receiving treatment with oral osimertinib 80mg tablet once a day. Following a week of osimertinib therapy, she developed rapidly progressive shortness of breath and was admitted due to hypoxic respiratory failure. Physical examination demonstrated tachypnea, tachycardia and decreased bilateral breath sounds. Community-acquired pneumonia, COVID-19 pneumonia, cardiogenic pulmonary edema, acute pulmonary embolism, progressive disease and lymphangitic carcinomatosis were excluded after extensive investigations. Laboratory investigations revealed mild leukocytosis with left shift, lactate of 2.5 mmol/L, CRP of 11.7 mg/dL, procalcitonin 0.2 ng/mL. EKG showed new onset atrial fibrillation. The COVID-19 PCR test was negative. Chest X-ray revealed bibasilar patchy airspace opacities majorly in the right lower lobe. She received empiric therapy with vancomycin and cefepime for suspected pneumonia and sepsis.

The woman's treatment with osimertinib was discontinued. Her respiratory failure worsened over the following days. A chest CT scan showed bilateral dense lower lobe consolidation and new onset bilateral pleural effusion with a decrease in the size of lung mass. Subsequently, she was diagnosed with osimertinib induced pneumonitis and interstitial lung disease. She started receiving treatment with unspecified corticosteroids and her symptoms improved within 24 hours of initiating steroid therapy. The antibiotic treatment was discontinued and was discharged on corticosteroid taper. Following 6 weeks of discharge, a repeat CT scan showed near total resolution of the infiltration, pleural effusions and pulmonary symptoms.

The woman, was restarted with osimertinib which was gradually increased to 80mg daily. She tolerated the osimertinib rechallenge well and remained asymptomatic.