In this explorative study, patients with resectabel cancer of the stomach or stomach-oesophagealjunction cancer will receive neoadjuvant treatment.

The treatment will be 1 cyle atzolizumab monotherapy, followed by 4 cycle of atezolizumab and capecitabine, oxaliplatin and docetaxel.

In this single-centre, open-label, monocenter study, the investigators will enroll 20 patients with resectable cancer of the stomach of GEJunction.

All patients will be treated with 1 cycle of atezolizumab monotherapy, followed by 4 cycles of combinationtherapy of atezolizumab, capecitabine, oxaliplatin and docetaxel, followed by surgery.

Inclusion Criteria:

• signed informed consent
• patients age 18 and older
• primary resectable, histologically confirmed gastric or GEJ adenocarcinoma

Exclusion Criteria:

• no signs of distant metastases
• no active or history of autoimmune disease or immune deficiency
• no significant cardiovascular disease
• no major surgical procedure within 4 weeks prior to initiation of study treatment
• no current treatment with anti-viral therapy or HBV
• no pregnancy or breastfeeding
• no history of malignancy within 3 years prior to screening