Stage I duodenal adenocarcinoma cured by a short treatment cycle of pembrolizumab: a case report

Abstract

Abstract Objectives The use of Immune checkpoint inhibitor (ICI) therapy (pembrolizumab) in duodenal cancer is rarely reported, and ICI therapy are mostly used in advanced-stage cancer according to its current indication. The case report aimed to demonstrate the special role of ICI therapy in early-stage duodenal cancer and discuss the possibility of modifying and broadening the indication of ICI therapy. Case presentation A female in her 70s were diagnosed early-stage tubular adenocarcinoma with immunohistochemistry showing deficiency in DNA mismatch repair (dMMR)/high microsatellite instability (MSI-H). Pembrolizumab was selected and the patient was treated regularly for 2 standard cycles. 5 months after the second cycle, the lesion showed no significant change, while 31 months after, the original lesion achieved almost complete remission. Conclusions ICI therapy may have unexpected effect on early-stage duodenal cancer and more specific indication of ICI treatment may be established.