PD-L2 biomarkers predictive of PD-1 pathway inhibitor responses in esophagogastric cancers

A method of treating an esophagogastric adenocarcinoma in a subject likely to be responsive to a PD-1 pathway inhibitor, the method comprising

• a) measuring the copy number, amount, or activity of PD-L2 in a subject sample obtained from a subject having esophagogastric adenocarcinoma;
• b) comparing the copy number, amount, or activity of PD-L2 in a control sample, and determining a significantly increased copy number, amount, or activity of PD-L2 in the subject sample relative to the control sample thereby identifying the esophagogastric adenocarcinoma as being likely to be responsive to the PD-1 pathway inhibitor;
• and
• c) administering the PD-1 pathway inhibitor to the subject likely to be responsive to the PD-1 pathway inhibitor.