Radiolabeled Probes Targeting Hypoxia-Inducible Factor-1-Active Tumor Microenvironments

Figure 2

Principle underlying the imaging of HIF-1-active tumor microenvironments, using ¹²³I -IPOS. The PTD enables ¹²³I-IPOS to be delivered to all tissues. In normoxic tissues, oxygen-dependent POS degradation occurs and ¹²³I-IBB loses its binding partner and is cleared. In contrast, in hypoxic tissues, ¹²³I-IPOS escapes degradation and is retained within cells owing to its molecular size. Thus, ¹²³I-IPOS allows for specific imaging of HIF-1-active hypoxic microenvironments.