Non-gestational choriocarcinoma is a rare and aggressive germ cell tumor. Here we present the case of a post-menopausal 49-year-old woman who presented with metastatic disease and initially achieved a complete radiographic and biomarker response with seven cycles of EMA-CO chemotherapy. Upon recurrence, she received two separate courses of chemotherapy, initially with paclitaxel/cisplatin/etoposide and later FOLFOX. Tumor analysis revealed 22% PD-L1 positivity (tumor proportion score) and she was treated with pembrolizumab. However, βhCG levels rose abruptly and uncharacteristically through all three cycles of anti-PD1 therapy. The patient developed dyspnea on exertion, cough, and right flank pain. CT imaging demonstrated marked progression of liver metastases and innumerable new pulmonary metastases and the patient died 10 weeks after starting pembrolizumab. Here we describe the clinical presentation and management of this patient, along with analysis of molecular aberrations which could potentially explain hyperprogression in response to pembrolizumab.

Immune checkpoint inhibitors (ICIs) are clinically used for treating advanced lung cancer, and some patients have achieved complete remission (CR) with ICI therapy in clinical trials. However, reports summarizing the clinical courses of such patients are limited. We report two cases of lung adenocarcinoma in which CR was achieved with first-line pembrolizumab monotherapy, and the therapeutic effect was maintained after treatment completion. Specific patients can achieve CR, even those who do not meet the previously reported predictors of treatment response other than high programmed death-ligand 1 expression. Thus, biomarkers that can accurately predict the clinical efficacy of ICIs are warranted.