PMC5470530_01
Radiological change after the treatment of nivolumab. (A) CT scan shows a large tumor mass in the left lower lung, and mediastinal lymphadenopathy. (B) Thirty-five days after the initiation of nivolumab. CT scan shows apparent regression of the tumor. Increase in the contralateral pleural effusion was also seen, which seems to be a transient immunologic reaction known as pseudo progression.
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However, CT findings on day 25 showed remarkable remission of the tumor (Fig. 1).
Comparison of the changes between X-ray evaluation, tumor marker, and the levels of ctDNA. Chest X-ray shows regression of the shadow 16 days after nivolumab treatment. Heat map shows 11 somatic mutations in the tissue obtained by needle lymph node biopsy before starting first-line treatment. Among them, TP53 and EGFRL858R were evaluated in the plasma samples as ctDNA. These ctDNA had rapidly decreased in only 5 days.
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TP53R249S mutation was finally almost undetectable. These changes had preceded and correlated with the radiological changes (Fig. 2).