Extended Data Fig. 1. Study design.

At baseline, all patients underwent FDG-PET and CT-scan as well as esophagoduodenoscopy with representative biopsies from tumor and normal tissue. Patients were treated with one cycle of atezolizumab 1200 mg monotherapy, followed by four combination cycles of atezolizumab 1200 mg, docetaxel 50 mg/m2, oxaliplatin 100 mg/m2 and capecitabine 850 mg. Representative biopsies from tumor and normal tissue were obtained after monotherapy atezolizumab and after the first combination cycle. Surgery was performed 6–9 weeks after the last treatment cycle and tissue was obtained from surgical resection specimens.