PMC8226096_01
Tumor progression of the patient before and after treatment. (A) The timeline of therapies and tumor progression are indicated (Top). CT images revealed lesions in lower left lung. The tumor is indicated by red arrows. PFS, progression-free survival; PR, partial response; SD, stable disease; PD, progressive disease; NGS, next-generation sequencing; mo., months. (B) Brain MRI scans revealed no metastasis before (October 2018) and after (September 2020) treatment. (C) Line chart showing changes in the levels of the serum tumor biomarker, CEA (carcinoembryonic antigen) during the course of treatment. (D) The EGFR p.E709_T710delinsD mutation was visualized by IGV software. Deletions are indicated with a black dash (-).
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Chinese female non-smoker with no family history of cancer suffered from repeated coughing for more than 10 days in October 2018. Computed tomography (CT) of the chest revealed a 5.1 x 3.6 cm density mass in the dorsal segment of the lower left lung ( Figure 1A ). Magnetic resonance imaging (MRI) scans showed that there were no metastases in the brain ( Figure 1B ). The level of the serum tumor biomarker, carcinoembryonic antigen (CEA), was 16.27 ng/mL, which was much higher than the normal range of < 5.0 ng/mL ( Figure 1C ). A rare EGFR exon 18 mutation (p.E709_T710delinsD) was identified with a mutant allele frequency (MAF) of 74.8%, and accompanied by EGFR amplification and a TP53 p.M246_T256del mutation ( Table 1  and  Figure 1D ). One month post treatment, a partial response (PR) was achieved with lesion shrinkage in the left lung according to the RECIST response criteria, and the serum CEA level returned to normal (4.58 ng/mL,  Figures 1A, C ). Seven months after afatinib treatment, the left lung tumor volume was further reduced, accompanied by a stable CEA level (6.87 ng/mL,  Figures 1A, C ). The lung lesion was re-evaluated using CT scans in December 2019 and revealed an increased tumor size ( Figure 1A ). The serum CEA level (15.80 ng/mL) was also elevated at that time ( Figure 1C ). In March 2020, CT scans revealed no marked enlargement of the lesion, while the CEA level was markedly elevated (32.05 ng/mL,  Figures 1A, C ). At that time, there was no metastasis in the brain, but the target lesion in the lower left lung increased with a concomitant increase in CEA levels (45.80 ng/mL), thus, indicating progressive disease (PD) ( Figure 1A-C ). In January 2021, although the lesion in the left lung was slightly enlarged and serum CEA levels (49.81 ng/mL) were higher than those in September 2020 ( Figures 1A, C ), the patient was considered as SD under the RECIST response criteria.