Two Cases of Squamous Cell Lung Carcinoma with EGFR Mutations Presenting Poor Outcomes After Osimertinib Treatment

Abstract

━━ Background. EGFR mutations are rarer in squamous cell carcinoma than in adenocarcinoma. The efficacy of osimertinib in treating squamous cell carcinoma with EGFR mutations has therefore not yet been investigated. Cases. (1) A 72-year-old man was diagnosed with postoperative recurrence of lung adenocarcinoma (pT2N2M0, stage IIIA, exon19 del). A biopsy was performed after treatment with afatinib and erlotinib. Simultaneously, squamous cell lung carcinoma manifestation and a T790M mutation were observed. Even after osimertinib administration for two months, the condition of the patient worsened. (2) A 70-year-old woman was diagnosed with squamous cell lung carcinoma (cT3N3M1c, stage IVB, L858R). After osimertinib administration for one month, brain metastasis worsened. Since the primary tumor shrank, whole-brain irradiation was performed, and osimertinib was continued. After three months, the primary tumor also worsened. Conclusion. These findings suggest that the efficacy of osimertinib for squamous cell lung carcinoma might be poor in some cases.

Efficacy of osimertinib for lung squamous cell carcinoma with de novo EGFR T790M‐positive: Case report and literature review

“…To the best of our knowledge, a literature search for case reports of osimertinib in SCC patients with EGFR mutation‐positive tumors, yielded 16 cases, including the present case 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 (Table 1 ). The treatment outcome breakdown was 12 cases of PR and four cases of PD, and many were reported to be effective, but the duration of response was limited in some cases.…”