case_images: PMC8600068_01
case_images: Histopathological and immunohistochemical staining of the lung tumor tissue sample. (A) Hematoxylin and eosin staining showing a poorly differentiated adenocarcinoma of primary biopsy (400x). (B) IHC staining showed ALK overexpression in 95% tumor cells of primary biopsy (400x). (C) IHC staining showed PD-L1 expression with Tumor Proportion Score 60% of primary biopsy (400x). (D, E) IHC staining CD4 and CD8 expression on T cells of rebiopsy showed that CD8 was positive (about 10%), and CD4 was only infiltrated individually (400x). IHC, immunohistochemical; ALK, anaplastic lymphoma kinase; PD-L1, Programmed cell death 1 ligand 1.
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case_images: PMC8600068_01_fimmu-12-686057-g001.jpg
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case_images: Biopsy of the left lower lobe mass suggested a diagnosis of poorly differentiated adenocarcinoma ( Figure 1A ), and immunohistochemistry (IHC) showed positive expression of ALK (by VENTANA D5F3, Ventana Medical Systems, Inc., Oro Valley, AZ) and PD-L1 (Tumor Proportion Score, TPS=60%, by 22C3 pharmDx assay, Dako, Carpinteria, CA, USA) ( Figures 1B, C ). Figures 1D, E ). Finally, the patient was switched to PD-1 inhibitor nivolumab monotherapy because he declined chemotherapy.
case_images: Time course depicting treatment process and radiological evaluation from 2018 to 2021. The PFS of crizotinib and ceritinib were 7 months and 3 months, respectively. And the duration of nivolumab was 18 months at the time of this report, and the patient is at present still on treatment and is receiving the drug. PR, partial response; PD, progressive disease; CR, complete response; CT, computed tomography; MRI, magnetic resonance imaging; PET/CT, positron emission tomography/computed tomography.
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case_images: The treatment process and radiological evaluation were summarized in  Figure 2 .