Gefitinib/rifampicin interaction

Abstract

Gefitinib/rifampicin interaction Pneumonia-type lung adenocarcinoma progression: case reportA 69-year-old woman developed pneumonia-type lung adenocarcinoma progression following concomitant administration of gefitinib and rifampicin for pneumonia-type lung adenocarcinoma and tuberculosis [not all dosages stated; routes not stated].The woman was hospitalised with complaints of cough, expectoration and weight loss for 3 months in January 2017. Initially, she was diagnosed with pneumonia, and started receiving treatment with unspecified antibiotics, with no improvement. Later, she was readmitted with the diagnosis of lung adenocarcinoma. Upon admission, based on multiple findings, final diagnosis of pneumoniatype lung adenocarcinoma with EGFR 19Del was consider. On 25 February 2017, she started receiving treatment with gefitinib 250mg daily, with almost complete resolution of the lesions. In November 2018, she again presented with a severe cough. At this time, she was diagnosed with concurrent tuberculosis (TB), and started receiving anti-TB therapy with pyrazinamide, ethambutol, isoniazid and rifampicin. In the first 2 months of treatment, her cough completely resolved and the sputum smear became negative. On completion of anti-TB therapy in May 2019, neoplastic lesions in the right lung increased gradually. Her CT-guided percutaneous lung biopsy, and the pathological result was still an adenocarcinoma. Based upon her medical history and clinical findings, it was concluded that co-administration of rifampicin (strong CYP3A4 inducer) and gefitinib (metabolised by CYP3A4 enzyme), decreased the concentration of gefitinib by increasing its metabolism, which led to the pneumonia-type lung adenocarcinoma progression.Therefore, the woman's gefitinib treatment was changed to osimertinib. After 38 months of follow-up, she was alive and was maintained on osimertinib treatment.