Severe stomatitis caused by osimertinib combined with gefitinib: A case report

The 2017 NCCN Guidelines for NSCLC recommend epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) as the first‐line treatment for patients with gene‐sensitive mutations of pulmonary adenocarcinoma. The TKI combination can effectively inhibit the gene mutations caused by the drug resistance and enhance the antitumor effect. However, more clinical investigations are required of the efficacy and the adverse drug reactions (ADRs) of this combination. A 62‐year‐old female patient diagnosed as lung adenocarcinoma with brain metastasis, meningeal metastasis, multiple bone metastasis, and liver metastasis was treated with the combination of gefitinib and osimertinib. Evident improvement was observed after 10 days of combined treatment with these tyrosine kinase inhibitors (TKIs), including in the CT features and symptoms. The level of tumor marker CEA decreased significantly after 40 days. However, severe stomatitis occurred after 49 days. By analyzing the relationship between stomatitis and TKI combined treatment based on the temporal correlation, instructions and literature reports, mechanisms, and reaction, we discovered that the combination of the two TKI drugs can increase the incidence and severity of severe stomatitis. Following targeted treatment and drug withdrawal, the patient fully recovered. TKI combination may increase the incidence and severity of stomatitis, suggesting that closely care and timely withdrawal are necessary measures.