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(124)I-huA33 antibody PET of colorectal cancer.

ABSTRACT: Humanized A33 (huA33) is a promising monoclonal antibody that recognizes A33 antigen, which is present in more than 95% of colorectal cancers and in normal bowel. In this study, we took advantage of quantitative PET to evaluate (124)I huA33 targeting, biodistribution, and safety in patients with colorectal cancer. We also determined the biodistribution of (124)I-huA33 when a large dose of human intravenous IgG (IVIG) was administered to manipulate the Fc receptor or when (124)I-huA33 was given via hepatic arterial infusion (HAI).We studied 25 patients with primary or metastatic colorectal cancer; 19 patients had surgical exploration or resection. Patients received a median of 343 MBq (44.4-396 MBq) and 10 mg of (124)I-huA33. Nineteen patients received the antibody intravenously and 6 patients via HAI, and 5 patients also received IVIG.Ten of 12 primary tumors were visualized in 11 patients. The median concentration in primary colon tumors was 0.016% injected dose per gram, compared with 0.004% in normal colon. The PET-based median ratio of hepatic tumor uptake to normal-liver uptake was 3.9 (range, 1.8-22.2). Quantitation using PET, compared with well counting of serum and tissue, showed little difference. Prominent uptake in bowel hindered tumor identification in some patients. Pharmacokinetics showed that patients receiving IVIG had a significantly shorter serum half-time (41.6 ± 14.0 h) than those without (65.2 ± 9.8 h). There were no differences in clearance rates among the intravenous group, IVIG group, and HAI group, nor was there any difference in serum area under the curve, maximum serum concentration, or volume of distribution. Weak titers of human-antihuman antibodies were observed in 6 of 25 patients. No acute side effects or significant toxicities were associated with huA33.Good localization of (124)I-huA33 in colorectal cancer with no significant toxicity has been observed. PET-derived (124)I concentrations agreed well with those obtained by well counting of surgically resected tissue and blood, confirming the quantitative accuracy of (124)I-huA33 PET. The HAI route had no advantage over the intravenous route. No clinically significant changes in blood clearance were induced by IVIG.

SUBMITTER: Carrasquillo JA

PROVIDER: S-EPMC3394182 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature

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(124)I-huA33 antibody PET of colorectal cancer.

Carrasquillo Jorge A JA Pandit-Taskar Neeta N O'Donoghue Joseph A JA Humm John L JL Zanzonico Pat P Smith-Jones Peter M PM Divgi Chaitanya R CR Pryma Daniel A DA Ruan Shutian S Kemeny Nancy E NE Fong Yuman Y Wong Douglas D Jaggi Jaspreet S JS Scheinberg David A DA Gonen Mithat M Panageas Katherine S KS Ritter Gerd G Jungbluth Achim A AA Old Lloyd J LJ Larson Steven M SM

Journal of nuclear medicine : official publication, Society of Nuclear Medicine 20110715 8

<h4>Unlabelled</h4>Humanized A33 (huA33) is a promising monoclonal antibody that recognizes A33 antigen, which is present in more than 95% of colorectal cancers and in normal bowel. In this study, we took advantage of quantitative PET to evaluate (124)I huA33 targeting, biodistribution, and safety in patients with colorectal cancer. We also determined the biodistribution of (124)I-huA33 when a large dose of human intravenous IgG (IVIG) was administered to manipulate the Fc receptor or when (124) ...[more]

PMID: 21764796

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Project description:Delta-like ligand 4 (Dll4) expressed in tumor cells plays a key role to promote tumor growth of numerous cancer types. Based on a novel antihuman Dll4 monoclonal antibody (61B), we developed a (64)Cu-labeled probe for positron emission tomography (PET) imaging of tumor Dll4 expression. In this study, 61B was conjugated with the (64)Cu-chelator DOTA through lysine on the antibody. Human IgG (hIgG)-DOTA, which did not bind to Dll4, was also prepared as a control. The Dll4 binding activity of the probes was evaluated through the bead-based binding assay with Dll4-alkaline phosphatase. The resulting PET probes were evaluated in U87MG glioblastoma and HT29 colorectal cancer xenografts in athymic nude mice. Our results demonstrated that the 61B-DOTA retained (77.2 ± 3.7) % Dll4 binding activity of the unmodified 61B, which is significantly higher than that of hIgG-DOTA (0.06 ± 0.03) %. Confocal microscopy analysis confirmed that 61B-Cy5.5, but not IgG-Cy5.5, predominantly located within the U87MG and HT29 cells cytoplasm. U87MG cells showed higher 61B-Cy5.5 binding as compared to HT29 cells. In U87MG xenografts, 61B-DOTA-(64)Cu demonstrated remarkable tumor accumulation (10.5 ± 1.7 and 10.2 ± 1.2%ID/g at 24 and 48 h postinjection, respectively). In HT29 xenografts, tumor accumulation of 61B-DOTA-(64)Cu was significantly lower than that of U87MG (7.3 ± 1.3 and 6.6 ± 1.3%ID/g at 24 and 48 h postinjection, respectively). The tumor accumulation of 61B-DOTA-(64)Cu was significantly higher than that of hIgG-DOTA-(64)Cu in both xenografts models. Immunofluorescence staining of the tumor tissues further confirmed that tumor accumulation of 61B-Cy5.5 was correlated well with in vivo PET imaging data using 61B-DOTA-(64)Cu. In conclusion, 61B-DOTA-(64)Cu PET probe was successfully synthesized and demonstrated prominent tumor uptake by targeting Dll4. 61B-DOTA-(64)Cu has great potential to be used for noninvasive Dll4 imaging, which could be valuable for tumor detection, Dll4 expression level evaluation, and Dll4-based treatment monitoring.

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(124)I-huA33 antibody PET of colorectal cancer.

Publications

(124)I-huA33 antibody PET of colorectal cancer.

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