RESUMO
Assessing lymph node (LN) status during tumor resection is fundamental for the staging of colorectal cancer. Current guidelines require a minimum of 12 LNs to be harvested during resection and ultra-staging regional lymph nodes by sentinel lymph node (SLN) assessment is being extensively investigated. The current study presents novel near-infrared (NIR) fluorescent dyes for simultaneous pan lymph node (PanLN; regional) and SLN mapping. PanLN-Forte was intravenously injected in mice and assessed for accumulation in regional LNs. SLN800 was injected intradermally in mice, after which the collection and retention of fluorescence in SLNs were measured using indocyanine green (ICG) and its precursor, SLN700, as references. LNs in the cervical, inguinal, jejunal, iliac, and thoracic basins could clearly be distinguished after a low dose intravenous injection of PanLN-Forte. Background fluorescence was significantly lower compared to the parent compound ZW800-3A (p < 0.001). SLN700 and SLN800 specifically targeted SLNs with fluorescence being retained over 40-fold longer than the current clinically used agent ICG. Using SLN700 and SLN800, absolute fluorescence in SLN was at least 10 times higher than ICG in second-tier nodes, even at 1 hour post-injection. Histologically, the fluorescent signal localized in the LN medulla (PanLN-Forte) or sinus entry (SLN700/SLN800). PanLN-Forte and SLN800 appear to be optimal for real-time NIR fluorescence imaging of regional and SLNs, respectively.
RESUMO
Purpose: AMG 211, a bispecific T-cell engager (BiTE) antibody construct, targets carcinoembryonic antigen (CEA) and the CD3 epsilon subunit of the human T-cell receptor. AMG 211 was labeled with zirconium-89 (89Zr) or fluorescent dye to evaluate the tumor-targeting properties.Experimental Design: 89Zr-AMG211 was administered to mice bearing CEA-positive xenograft tumors of LS174T colorectal adenocarcinoma or BT474 breast cancer cells, as well as CEA-negative HL-60 promyelocytic leukemia xenografts. Biodistribution studies with 2- to 10-µg 89Zr-AMG211 supplemented with unlabeled AMG 211 up to 500-µg protein dose were performed. A BiTE that does not bind CEA, 89Zr-Mec14, served as a negative control. 89Zr-AMG211 integrity was determined in tumor lysates ex vivo Intratumoral distribution was studied with IRDye800CW-AMG211. Moreover, 89Zr-AMG211 was manufactured according to Good Manufacturing Practice (GMP) guidelines for clinical trial NCT02760199Results: 89Zr-AMG211 demonstrated dose-dependent tumor uptake at 6 hours. The highest tumor uptake was observed with a 2-µg dose, and the lowest tumor uptake was observed with a 500-µg dose. After 24 hours, higher uptake of 10-µg 89Zr-AMG211 occurred in CEA-positive xenografts, compared with CEA-negative xenografts. Although the blood half-life of 89Zr-AMG211 was approximately 1 hour, tumor retention persisted for at least 24 hours. 89Zr-Mec14 showed no tumor accumulation beyond background level. Ex vivo autoradiography revealed time-dependent disintegration of 89Zr-AMG211. 800CW-AMG211 was specifically localized in CEA-expressing viable tumor tissue. GMP-manufactured 89Zr-AMG211 fulfilled release specifications.Conclusions: 89Zr-AMG211 showed dose-dependent CEA-specific tumor targeting and localization in viable tumor tissue. Our data enabled its use to clinically evaluate AMG 211 in vivo behavior. Clin Cancer Res; 24(20); 4988-96. ©2018 AACR.
