PT - JOURNAL ARTICLE AU - YOSUKE SHIONOYA AU - YOSHIHIKO HIROHASHI AU - HARUKA TAKAHASHI AU - MIDORI HASHIMOTO AU - KAORU NISHIYAMA AU - YASUNARI TAKAKUWA AU - MUNEHIDE NAKATSUGAWA AU - TERUFUMI KUBO AU - TAKAYUKI KANASEKI AU - TOMOHIDE TSUKAHARA AU - TOSHIHIKO TORIGOE TI - Possible Pseudo-progression of Non-small Cell Lung Carcinoma in a Patient With Clinical Hyper-progression Associated With Trousseau Syndrome Who Was Treated With Pembrolizumab: A Case Report AID - 10.21873/anticanres.15161 DP - 2021 Jul 01 TA - Anticancer Research PG - 3699--3706 VI - 41 IP - 7 4099 - http://ar.iiarjournals.org/content/41/7/3699.short 4100 - http://ar.iiarjournals.org/content/41/7/3699.full SO - Anticancer Res2021 Jul 01; 41 AB - Background/Aim: Immune checkpoint inhibitors (ICIs), including nivolumab and pembrolizumab, have recently been shown to have clinical benefits in patients with advanced non-small cell lung cancer (NSCLC). The novel tumour responses to these agents are changing the management of patients with cancer. Pseudo-progression of disease (pseudo-PD), that is, an initial flare followed by shrinkage of the tumour, has been described as a distinctive response to ICIs. However, pseudo-PD manifest initial progression and is difficult to segregate with hyper progressive disease (HPD). We, therefore, analysed a case with pseudo-PD histologically. Patients and Methods: A 68-year-old Japanese man with stage IV non-small cell lung carcinoma (NSCLC) was treated by anti-PD-1 antibody (pembrolizumab). Four weeks later after second time treatment with pembrolizumab, the patient showed severe melena followed by Trousseau syndrome and died at day 174 after first treatment by pembrolizumab, suggesting HPD clinically. Primary lesion and metastatic lesions were analysed histologically. Results: Histological analysis revealed that NSCLC cells expressed PD-L1, and CD8+ tumor-infiltrated lymphocytes (TILs) were observed. CD8+ TILs showed higher rates of PD-1 indicating that lesions were of the inflamed type and the case was pseudo-PD. Furthermore, it was found that cancer cells expressed MUC1. Conclusion: The clinical appearance of the case was aggressive after treatment by pembrolizumab, and the case seemed to be HPD; however, histological analysis revealed that the case was likely pseudo-PD. Therefore, careful histological evaluation is important when investigating the clinical response to an ICI and mucin expression might be a predictive marker for Trousseau syndrome.