Planning treatment for oesophago-gastric cancer: a randomised maintenance therapy trial (PLATFORM Trial)

• Histologically verified inoperable locally advanced or metastatic adenocarcinoma of the oesophagus, oesophagogastric junction, or stomach. • Completion of at least 6 cycles of firstline chemotherapy for locally advanced / metastatic disease (this must have included a platinum and fluoropyrimidine in all cases; HER2 positive patients must have received trastuzumab alongside chemotherapy) with > stable disease on the end of treatment CT scan. • Disease which, following firstline chemotherapy, remains inoperable and unsuitable for definitive chemoradiotherapy. • Able to proceed with maintenance treatment within 28 days of the last day of the last cycle of chemotherapy. • Formalin fixed paraffin embedded (FFPE) blocks of diagnostic tissue available for biomarker analysis. • Unidimensionally measurable disease (CT or MRI as per RECIST). • Any prior chemotherapy or radiotherapy in the adjuvant setting must have been completed at least 6 months prior to the first occurrence of metastatic disease. • No prior radiotherapy in the advanced disease setting. Patients receiving palliative radiotherapy to sites of disease that are not measurable may be eligible and should be discussed with the Chief Investigator. • Male/female patients aged ≥18 years. • WHO Performance status 0, 1 or 2. • Patients should have a projected life expectancy of at least 3 months. • Adequate bone marrow function: absolute neutrophil count (ANC) ≥1.5x109/l; white blood cell count ≥ 3x109/l; platelets ≥ 100x109/l; haemoglobin (Hb) ≥ 9g/dl (can be posttransfusion). • Adequate renal function: calculated creatinine clearance ≥50ml/minute. • Adequate liver function: serum bilirubin ≤1.5x ULN; aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase ≤2.5 x ULN (5 × ULN is acceptable for ALT, AST and ALP if liver metastases are present). • Women of childbearing potential as well as fertile men and their partners must agree to abstain from sexual intercourse or to use an effective form of contraception during the study and for 60 days following the last dose of assigned study drug(s). • Written informed consent must be obtained from the patient before any study-specific procedures are performed.

• Concurrent enrolment in another clinical trial unless it is an observational (noninterventional) clinical study. • Tumours of squamous histology. • Documented brain metastases, central nervous system metastases or leptomeningeal disease. • Patients who have not recovered from clinically significant effects of any prior surgery, radiotherapy or any other antineoplastic therapies. All toxicities must have resolved to grade 1 or less, with the exception of peripheral neuropathy which must be < grade 2 according to NCI CTCAE version 4.0. • Any major surgery within 4 weeks prior to the start of study treatment. • Uncontrolled hypertension (systolic blood pressure > 180 mm Hg or diastolic blood pressure > 100 mm Hg). • Clinically significant (i.e. active) cardiac disease e.g. symptomatic coronary artery disease, symptomatic congestive heart failure, uncontrolled cardiac dysrhythmia, or myocardial infarction within the last 12 months. Patients with any prior history of clinically significant cardiac failure are excluded from study entry. • History of interstitial lung disease (e.g., pneumonitis or pulmonary fibrosis) or evidence of interstitial lung disease on baseline chest CT scan. • Lack of physical integrity of the upper gastrointestinal tract, malabsorption syndrome, or inability to take oral medication. • Patients who are pregnant or lactating. • Known positive tests for human immunodeficiency virus (HIV) infection, hepatitis A or C virus, acute or chronic active hepatitis B infection. • Other clinically significant disease or comorbidity which may adversely affect the safe delivery of treatment within this trial. • Any other malignancies within the last 3 years (other than curatively treated basal cell carcinoma of the skin and/or in situ carcinoma of the cervix). • Treatment with another investigational agent within 30 days of commencing study treatment.