123I-IPOS is a potential probe for imaging HIF-1- active tumors. However, because of its large molecular size (34 kDa), 123I-IPOS is slowly cleared from the blood; therefore, a high tumor-to-normal tissue ratio cannot be obtained quickly after probe injection. To overcome this problem, Ueda et al., proposed a pre- targeting method based on the high-affinity interaction between streptavidin and biotin. The principle of the pretargeted imaging of HIF-1-active tumor regions is outlined in Fig.15.2a. First, POS was administered and allowed to undergo degradation in normal regions; sub- sequently, 123I-IBB was administered. Because POS has been degraded and expelled, 123I-IBB is not retained in normal regions. However, POS is retained in HIF-1-active regions, and123I-IBB binds to the POS in these regions; specific imaging of such regions can then be achieved.
An examination of the biodistribution of 125I-IBB alone revealed that the tumor-to-blood ratio was less
than 1 at all time points. This indicated that125I-IBB did not accumulate in tumors (Ueda et al., 2010). In contrast, in the pretargeted group, the tumor-to-blood ratio was greater than 1 as early as 1 h after the injection of 125I-IBB, and the tumor-to-blood ratio increased in a time-dependent manner. The blood clearance in both groups was comparable. In the pre- targeted group, the tumor accumulation of 125I-IBB 6 h after its injection was more than 30-fold higher than that in the case of 125I-IBB alone (Ueda et al., 2010). Moreover, the tumoral uptake of 125I-IBB in the POS-pretargeted group was significantly reduced by treatment with D-biotin or non-radioactive IBB.
Size-exclusion analysis of radioactive compounds in tumors revealed that a major proportion of the radioac- tivity was attributable to macromolecules. Collectively, these findings indicate that radioactivity in the tumor is caused by the binding of125I-IBB to the SAV moiety of POS in vivo.
Figure 15.2b illustrates the accumulation of 123I- IBB in a POS-pretargeted tumor. The tumor was clearly visualized 6 h after 123I-IBB injection, and the image was comparable to that obtained 24 h after
123I-IPOS injection (Fig. 15.1b). Using the pretarget- ing approach, the tumoral accumulation (1.6% injected dose per gram tissue [ID/g]) and the tumor-to-blood ratio (4.2) 6 h after injection (Ueda et al.,2010) were comparable to the findings 24 h after125I-IPOS injec- tion (1.4% ID/g, 5.1) (Kudo et al.,2009). The images of the pretargeted mice clearly indicated that123I-IBB accumulated in the tumor more rapidly and cleared much more promptly from the body than 123I-IPOS.
These results indicate that the pretargeting approach shortens the time required to obtain an adequate image by 75%.
A highly significant correlation was observed between 125I-IBB accumulation and HIF-1 transcrip- tional activity in the same tumor in POS-pretargeted mice (Ueda et al., 2010), when the tumoral accu- mulation of 125I-IBB was compared with HIF-1 transcriptional activity using mice bearing tumors expressing the HIF-1-dependent luciferase reporter gene (Kizaka-Kondoh et al., 2009a). The autora- diographic study revealed that the intratumoral distribution of125I-IBB was heterogeneous and signif- icantly correlated with HIF-1α-positive regions in the POS-pretargeted tumor. These findings indicate that the accumulation of 125I-IBB in the POS-pretargeted tumor reflects the expression of HIF-1.
15 Imaging of Hypoxia-Inducible Factor-1-Active Regions in Tumors Using a POS and I-IBB Method 133
Fig. 15.2 (a) Concept of hypoxia imaging using the pre- targeting approach. PTD: protein transduction domain, ODD: oxygen-dependent degradation domain (HIF- 1α 548–603), SAV: monomeric streptavidin, 123I-IBB:
(3-[123I]iodobenzoyl)norbiotinamide. (b) Scintigraphic image of a POS-pretargeted mouse at 6 h after injection of123I-IBB.
The tumor xenografted in the right thigh was clearly visualized (circle). The arrowhead indicates the liver and intestine
In conclusion, using the pretargeting approach, clear tumor images were obtained in a shorter time than was possible with the direct labeling method. Intratumoral accumulations of 125I-IBB in the POS-pretargeted tumors were significantly correlated with HIF-1αposi- tivity. These findings demonstrate that the pretargeting method with POS and 123I-IBB is effective for the rapid imaging of HIF-1-active hypoxic tumors.
References
Chitneni SK, Palmer GM, Zalutsky MR, Dewhirst MW (2011) Molecular imaging of hypoxia. J Nucl Med 52:165–168.
Eltzschig HK, Carmeliet P (2011) Hypoxia and inflammation. N Engl J Med 364:656–665.
Fernandes-Alnemri T, Litwack G, Alnemri ES (1994) CPP32, a novel human apoptotic protein with homology to Caenorhabditis elegans cell death protein Ced-3 and mam- malian interleukin-1 beta-converting enzyme. J Biol Chem 269:30761–30764.
Goldenberg DM, Rossi EA, Sharkey RM, McBride WJ, Chang CH (2008) Multifunctional antibodies by the Dock-and- Lock method for improved cancer imaging and therapy by pretargeting. J Nucl Med 49: 158–163.
Harada H, Hiraoka M, Kizaka-Kondoh S (2002) Antitumor effect of TAT-oxygen-dependent degradation-caspase-3 fusion protein specifically stabilized and activated in hypoxic tumor cells. Cancer Res 62:2013–2018.
Harada H, Kizaka-Kondoh S, Hiraoka M (2005) Optical imaging of tumor hypoxia and evaluation of efficacy of a hypoxia- targeting drug in living animals. Mol Imaging 4:182–193.
He J, Wang Y, Dou S, Liu X, Zhang S, Liu G, Hnatowich D (2010) Affinity enhancement pretargeting: synthesis and
testing of a 99mTc-labeled bivalent MORF. Mol Pharm 7:1118–1124.
Kizaka-Kondoh S, Itasaka S, Zeng L, Tanaka S, Zhao T, Takahashi Y, Shibuya K, Hirota K, Semenza GL, Hiraoka M (2009a) Selective killing of hypoxia-inducible factor-1-active cells improves survival in a mouse model of invasive and metastatic pancreatic cancer. Clin Cancer Res 15:3433–3441.
Kizaka-Kondoh, S., and Konse-Nagasawa, H (2009) Significance of nitroimidazole compounds and hypoxia- inducible factor-1 for imaging tumor hypoxia. Cancer Sci.
100: 1366–1373.
Kizaka-Kondoh S, Tanaka S, Harada H, Hiraoka M (2009b) The HIF-1-active microenvironment: an environmental target for cancer therapy. Adv Drug Deliv Rev 61:623–632.
Kuchimaru T, Kadonosono T, Tanaka S, Ushiki T, Hiraoka M, Kizaka-Kondoh S (2010) In vivo imaging of HIF-active tumors by an oxygen-dependent degradation protein probe with an interchangeable labeling system. PloS One 5:e15736.
Kudo T, Ueda M, Kuge Y, Mukai T, Tanaka S, Masutani M, Kiyono Y, Kizaka-Kondoh S, Hiraoka M, Saji H (2009) Imaging of HIF-1-active tumor hypoxia using a protein effec- tively delivered to and specifically stabilized in HIF-1-active tumor cells. J Nucl Med 50:942–949.
Sadeghi MM, Glover DK, Lanza GM, Fayad ZA, Johnson LL (2010) Imaging atherosclerosis and vulnerable plaque. J Nucl Med 51 Suppl 1:51S–65S.
Sano K, Temma T, Kuge Y, Kudo T, Kamihashi J, Zhao S, Saji H (2010) Radioimmunodetection of membrane type-1 matrix metalloproteinase relevant to tumor malignancy with a pre- targeting method. Biol Pharm Bull 33:1589–1595.
Schwarze SR, Ho A, Vocero-Akbani A, Dowdy SF (1999).
In vivo protein transduction: delivery of a biologically active protein into the mouse. Science 285:1569–1572.
Semenza GL (2010a) Defining the role of hypoxia-inducible factor 1 in cancer biology and therapeutics. Oncogene 29:
625–634.
Semenza GL (2010b) HIF-1: upstream and downstream of cancer metabolism. Curr Opin Genet Dev 20:51–56.
Sharkey RM, Cardillo TM, Rossi EA, Chang CH, Karacay H, McBride WJ, Hansen HJ, Horak ID, Goldenberg DM (2005) Signal amplification in molecular imaging by pre- targeting a multivalent, bispecific antibody. Nat Med 11:
1250–1255.
Sharkey RM, Karacay H, Litwin S, Rossi EA, McBride, WJ, Chang CH, Goldenberg DM (2008). Improved therapeutic results by pretargeted radioimmunotherapy of non-Hodgkin’s lymphoma with a new recombinant, trivalent,
anti-CD20, bispecific antibody. Cancer Res 68:5282–
5290.
Ueda M, Kudo T, Kuge Y, Mukai T, Tanaka S, Konishi H, Miyano A, Ono M, Kizaka-Kondoh S, Hiraoka M, Saji H (2010) Rapid detection of hypoxia-inducible factor-1-active tumours: pretargeted imaging with a protein degrading in a mechanism similar to hypoxia-inducible factor-1alpha. Eur J Nucl Med Mol Imaging 37:1566–1574.
Wu Z, Kandeel F (2010) Radionuclide probes for molecu- lar imaging of pancreatic beta-cells. Adv Drug Deliv Rev 62:1125–1138.