Clinical advances in TNC delivery vectors and their conjugate agents

Tenascin C (TNC), a glycoprotein that is abundant in the tumor extracellular matrix (ECM), is strongly overexpressed in tumor tissues but virtually undetectable in most normal tissues. Many TNC antibodies, peptides, aptamers, and nanobodies have been investigated as delivery vectors, including 20A1, α-A2, α-A3, α-IIIB, α-D, BC-2, BC-4 BC-8, 81C6, ch81C6, F16, FHK, Ft, Ft-NP, G11, G11-iRGD, GBI-10, 19H12, J1/TN1, J1/TN2, J1/TN3, J1/TN4, J1/TN5, NJT3, NJT4, NJT6, P12, PL1, PL3, R6N, SMART, ST2146, ST2485, TN11, TN12, TNFnA1A2-Fc, TNfnA1D-Fc, TNfnBD-Fc, TNFnCD-Fc, TNfnD6-Fc, TNfn78-Fc, TTA1, TTA1.1, and TTA1.2. In particular, BC-2, BC-4, 81C6, ch81C6, F16, FHK, G11, PL1, PL3, R6N, ST2146, TN11, and TN12 have been tested in human tissues. G11-iRGD and simultaneous multiple aptamers and arginine–glycine–aspartic acid (RGD) targeting (SMART) may be assessed in clinical trials because G11, iRGD and AS1411 (SMART components) are already in clinical trials. Many TNC-conjugate agents, including antibody–drug conjugates (ADCs), antibody fragment–drug conjugates (FDCs), immune-stimulating antibody conjugates (ISACs), and radionuclide–drug conjugates (RDCs), have been investigated in preclinical and clinical trials. RDCs investigated in clinical trials include 111In-DTPA-BC-2, 131I-BC-2, 131I-BC-4, 90Y-BC4, 131I81C6, 131I-ch81C6, 211At-ch81C6, F16124I, 131I-tenatumomab, ST2146biot, FDC 131I-F16S1PF(ab')2, and ISAC F16IL2. ADCs (including FHK-SSL-Nav, FHK-NB-DOX, Ft-NP-PTX, and F16*-MMAE) and ISACs (IL12-R6N and 125I-G11-IL2) may enter clinical trials because they contain components of marketed treatments or agents that were investigated in previous clinical studies. This comprehensive review presents historical perspectives on clinical advances in TNC-conjugate agents to provide timely information to facilitate tumor-targeting drug development using TNC.