Consistent with our in vivo results, ex vivo organ biodistribution analysis of the tumors, muscle, and blood revealed increased 89Zr-mCD4-Mb accumulation in the TME and significantly higher tumor-to-blood and tumor-to-muscle ratios in mice responding to ICI non-responsive MC38 tumors or tumors from sham-treated experimental mice (Figure 5I; Figure S5D). This evidence concerns the gene MB and neoplasm.