PMC8140796_01
(A) Fluctuation of CEA (normal value: 0-5 mug/L) and CA 125 (normal value: 0-35 U/L) levels in the blood. (B) Fluctuation of CA 19-9 (normal value: 0-39 U/mL) levels and AF of ctDNA ELM4-ALK fusion in the blood. AF, allele frequency; CA, carbohydrate antigen; CEA, carcinoembryonic antigen; ctDNA, circulating tumor DNA.
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fig1
CA19-9 significantly increased (Figs 1A and 1B). Colonoscopy pathology reported moderately to poorly differentiated adenocarcinoma (Fig 2A), and immunohistochemistry (IHC) demonstrated positivity for CK20 (Fig 2B). After a month, computed tomography scans revealed partial response (PR) for retroperitoneal lymphadenectasis and liver metastases based on RECIST 1.1 (Fig 4) and concomitant decrease in serum CEA and CA 19-9 (Figs 1A and 1B). TP53 mutation (0.3%) (Table 1 and Fig 1A).
H&E staining (A), 100x, and IHC, (B) for CK20 (+), (C) for Ki-67 (-), and (D) for IHC with D5F3 anti-ALK Ventana antibody showing strong staining and verifying ALK overexpression as a result of EML4-ALK fusion. ALK, anaplastic lymphoma kinase; H&E, hematoxylin and eosin; IHC, immunohistochemistry.
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fig2
CA19-9 significantly increased (Figs 1A and 1B). Colonoscopy pathology reported moderately to poorly differentiated adenocarcinoma (Fig 2A), and immunohistochemistry (IHC) demonstrated positivity for CK20 (Fig 2B). The IHC results showing strong D5F3 anti-ALK antibody of Ventana staining verified ALK overexpression as a result of EML4-ALK fusion (Fig 2D). The first XELOX (capecitabine, 1.5g, d1-14 + oxaliplatin, 200mg, d1, q3w) cycle was interrupted because of the patient's intestinal obstruction after she had taken oral capecitabine for 1 week.
NGS showing EML4-ALK fusion (E21;A20) on (A) FFP and (B) CSF, in which the AF is 21.5% and 99%, respectively. AF, allele frequency; ctDNA, circulating tumor DNA; FFP, fresh frozen plasma; NGS, next-generation sequencing; PR, partial response.
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fig3
mCRC treatment using different regimens and results of NGS ctDNA monitoring in plasma. AF, allele frequency; ctDNA, circulating tumor DNA; mCRC, metastatic colorectal carcinoma; MRI, magnetic resonance imaging; NGS, next-generation sequencing; PR, partial response.
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fig4
After a month, computed tomography scans revealed partial response (PR) for retroperitoneal lymphadenectasis and liver metastases based on RECIST 1.1 (Fig 4) and concomitant decrease in serum CEA and CA 19-9 (Figs 1A and 1B). Brain MRI demonstrated diffuse linear enhancement of the cerebral sulci (Fig 4).