Checkpoint Inhibitors in Bone Metastatic Disease in Solid Tumors.

Purpose of review: Bone is a common site of metastatic spread for solid tumors. Bone as an organ serves unique roles in the body's structural integrity, hematopoiesis, and the development of immune modulating cells. With the increasing use of immunotherapy, specifically immune checkpoint inhibitors, understanding the response of bone metastases is necessary.

Recent findings: The data on checkpoint inhibitors used for managing solid tumors are reviewed here with a focus on bone metastases. Albeit with limited available data, there is a trend toward poorer outcomes in this setting, presumably due to the unique immune microenvironment within bone and bone marrow. Despite the potential to improve cancer outcomes with use of ICIs, bone metastases remain challenging to manage and may have different responses to ICIs than other disease sites. Areas for future investigation include a nuanced understanding of the bone microenvironment and dedicated research aimed at specific bone metastases outcomes.