Lung Adenocarcinoma Size Decrease after SARS-CoV-2 Vaccination during Long-Term Pembrolizumab Treatment: A Case Report

A man in his late 40s was diagnosed with clinical stage 4B lung adenocarcinoma with a PD-L1 tumor proportion score of 100% and high tumor mutational burden. A partial response was achieved after administration of pembrolizumab. The patient received two doses of a SARS-CoV-2 vaccine (BNT162b2) after 59 courses, and a chest computed tomography revealed consolidation in the peri-tumoral area, which subsequently disappeared, and the tumor continued to shrink in the next 4 months. This case provides indirect evidence for the persistence of cancer immunity during long-term treatment with immune checkpoint inhibitors and the potential for further activation.