430 Immune Checkpoint Inhibitors in Oesophago-Gastric Cancer - Making the Unresectable, Resectable

Abstract The primary role of PDL-1 immune checkpoint inhibitors in oesophageal and gastric cancers in the UK is in the metastatic adjuvant setting. Currently here in the NHS there is no role or recommendation for their use in resectable / locally advanced disease. Emerging data however from early-phase trials suggest that adding ICIs to neoadjuvant or perioperative regimens can increase pathologic complete response rates and radiologic responses in locally advanced disease, which may theoretically increase the likelihood of achieving resectability in select patients. We present two cases from our institution of young patients who presented with metastatic, unresectable disease with MSI high PDL-1 positive tumours - one SCC and the other adenocarcinoma. Following treatment with PDL-1 inhibitors and palliative chemotherapy they went on to have a period of significant disease stability contrary to their original tumour pathology and subsequent re-staging suggested disease regression and potential respectability. Following extensive MDM discussion, they both proceeded to curative oesophagectomy with final post-op pathology for both showing complete pathological response. The authors suggest furthers research into this subset of patients with the aim of refining the treatment algorithm for patients presenting with PDL- 1 positive metastatic gastro-oesophageal malignancy to include full re-staging on completion of first line palliative chemo-immunotherapy to aid identifying those who can be made resectable.