Parallel genomic and immune profiling of relapsed and metastatic osteosarcoma to reveal bases of low immunogenicity.

10520 Background: Despite the high levels of point mutations, rearrangements, and other genomic instability events such as kataegis and chromothripsis, immune checkpoint inhibitors have shown limited clinical activity in osteosarcoma (OS). We completed in-depth parallel genomic and immune profiling in a cohort of 48 patients with high-grade osteosarcoma (relapsed or metastatic in 42) to determine potential mechanisms of primary resistance to...