Durable pembrolizumab response in metastatic MSS ARID1A-mutant undifferentiated carcinoma of the esophagus

Abstract

In 2021, the FDA approved the combination of pembrolizumab with platinum and fluoropyrimidine-based chemotherapy for advanced esophageal and gastroesophageal junction (GEJ) cancers, regardless of the PD-L1 score. Pembrolizumab alone may benefit MSI-H gastroesophageal adenocarcinomas, but most patients with pMMR/MSS types require it in combination with standard chemotherapy. The NCCN recognizes the predictive value of PD-L1 CPS and recommends pembrolizumab plus chemotherapy for PD-L1 CPS ≥10. Undifferentiated carcinoma of the esophagus, a rare esophageal cancer subtype with a poor prognosis, still lacks a well-defined optimal treatment. We report a case of an 87-year-old female with advanced, pMMR/MSS, HER2-negative, ARID1A-mutant, undifferentiated carcinoma of the esophagus with a PD-L1 CPS of 20, who has shown a durable ongoing response to pembrolizumab monotherapy for 2 years now. The case highlights a favorable response, possibly attributed to the high CPS score combined with the ARID1A mutation, as recent research suggests that ARID1A mutations may increase immunotherapy susceptibility.

Keywords:

• Immunotherapy
• Gastrointestinal Cancers
• Genetics

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

There is no data set associated with the paper

Patient Consent

We have obtained written informed consent to publish the details from the affected individual.