Tailing effect of PD-1 antibody results in the eradication of unresectable multiple primary lung cancer presenting as ground-glass opacities: a case report

: There is currently no standard treatment for multiple primary lung cancer (MPLC). We report a case of synchronous MPLC presenting as one ground-glass opacity (GGO) with predominant consolidation accompanied by at least parietal pleura involvement, and another >30 GGOs distributed across bilateral lungs, which was ineligible complete resection. CT-guided percutaneous biopsy the nearly pure-solid mass showed invasive adenocarcinoma mainly composed acinar type. Capture-based, ultra-deep targeted sequencing (Burning Rock, Guangzhou, China) performed on tumor tissue biopsy. The result revealed druggable mutations according to guideline high TMB 34.1 Mb. Immunohistochemical staining (22C3; Dako, Denmark) positive PD-L1 expression level 30%. Based clinical information patient’s decision, he received 3 cycles pemetrexed plus pembrolizumab subsequently forced withdraw due acquired immune-related pneumonitis. After discontinuation corticosteroids, subjected wedge resection lesion, then refused further other tumors. follow-up 12 months from termination immunotherapy, almost all achieved radiographically remission, attributed tailing effect programmed cell death protein 1 (PD-1) antibody pembrolizumab. Through study we found that unresectable may respond well immunotherapy.