TPS471 Background: Oesophagogastric (OG) cancers represent a significant health burden and leading cause of cancer related death. Prognosis in advanced disease is poor and novel therapies are needed to improve outcomes. Molecular features of advanced OG cancer suggest that assessment of DDR (DNA damage repair) targeted agents is warranted. Specifically, ATM and ARID1A defects and mutational scars indicative of homologous recombination defects are present in a subset of OG cancers and are associated with polyadenosine 5’diphosphoribose polymerase inhibitor (PARPi) sensitivity. Methods: SOlar is a multi-centre, open-label, single arm, phase II study of olaparib, a PARPi, in patients with advanced oesophageal, gastro-oesophageal junction and gastric adenocarcinoma. The trial will use a single-arm Simon two-stage design to evaluate the anti-tumour activity of olaparib in advanced OG cancers. The primary endpoint is disease control rate (DCR) at 8 weeks by RECIST v1.1. To rule out a DCR of ≤15% while aiming for DCR ≥30% (alpha = 0.09, power = 89%), 54 patients must be recruited it total. An interim analysis will take place when 27 patients have been accrued, dosed and followed until the 8-week disease evaluation. If 4 or fewer patients have disease control (DC) the study will be terminated. If 5 or more patients have DC, an additional 27 patients will be enrolled to a total of 54 patients. If ≥12/54 have DC in the final analysis then it will be concluded that the treatment has shown anti-tumour activity compatible with 30% and an investigation of potential biomarkers of response will be carried out. Secondary endpoints are ORR, DoR, OS, PFS, time to radiological progression and safety. This highly translational study incorporating serial tumour biopsies will investigate candidate predictive biomarkers of PARPi sensitivity with the aim of identifying responder/non-responder subpopulations. Further exploratory objectives will investigate the predictive role of early FDG-PET/CT in assessing tumour response and the creation of an organoid biobank. The trial opened to recruitment in July 2019 and will recruit up to 54 patients over 3 years. Clinical trial information: NCT03829345.
922P EACH: A phase II study evaluating the safety and anti-tumour activity of avelumab and cetuximab in recurrent/metastatic squamous cell carcinomas
