摘要
BACKGROUND Although common in lung cancer,somatic epidermal growth factor receptor(EGFR)mutations are rarely found in colorectal cancer,occurring in approximately 3%of cases.Treatment with anti-EGFR antibodies is commonplace,but EGFR tyrosine kinase inhibitors are not standard treatments in colorectal cancer.Here we report a case of sustained response to osimertinib in a colorectal cancer patient with an EGFR T790M mutation on cell-free DNA analysis.CASE SUMMARY A 72-year old woman with a past medical history of post-polio syndrome confined to a wheelchair,scoliosis and hypothyroidism presented with metastatic sigmoid colon adenocarcinoma with hepatic metastases.Next generation sequencing revealed a RAS/RAF wild-type,microsatellite stable,PD-L1 negative malignancy.Mutations in TP3 and APC were also identified,as well as EGFR amplification.Cell-free DNA analysis revealed an EGFR T790M mutation.She was unable to tolerate first-line treatment with panitumumab,5-fluorouracil and leucovorin,progressed on second-line treatment with trifluridine/tipiracil plus bevacizumab,and was unable to tolerate third-line treatment with regorafenib.She was started on fourth-line treatment with off-label osimertinib,with clinical response–decrease in size of hepatic metastases and a pericardial effusion.She remained on treatment with osimertinib for seven months.CONCLUSION This case shows the benefit of multi-gene sequencing assays to identify potential therapeutic options in patients with refractory disease.
