The efficacy of a CXCR2‐blocking antibody in preventing breast cancer metastasis to bone was studied in a bone OoC platform.[87] Because CXCR2 is an important factor in promoting the colonization of breast cancer cells in bone cells, this targeting agent was highly effective in suppressing extravasation and metastasis.[87] However, the CXCR2‐blocking antibody used is not a fully developed cancer therapeutic; thus, no animal studies or clinical trials can support these results. The gene discussed is CXCR2; the disease is breast cancer.