Targeting human prostate cancer with ¹¹¹In‐labeled D2B IgG, F(ab′)₂ and Fab fragments in nude mice with PSMA‐expressing xenografts

Abstract

D2B is a new monoclonal antibody directed against an extracellular domain of prostate-specific membrane antigen (PSMA), which is overexpressed in prostate cancer. The potential of D2B IgG, and F(ab')2 and Fab fragments of this antibody for targeting prostate cancer was determined in mice bearing subcutaneous prostate cancer xenografts. The optimal time point for imaging was determined in biodistribution and microSPECT imaging studies with (111)In-D2B IgG, (111)In-capromab pendetide, (111)In-D2B F(ab')2 and (111)In-D2B Fab fragments in mice with PSMA-expressing LNCaP and PSMA-negative PC3 tumors at several time points after injection. All (111)In-labeled antibody formats specifically accumulated in the LNCaP tumors, with highest uptake of (111)In-D2B IgG and (111)In-capromab pendetide at 168 h p.i. (94.8 ± 19.2% injected dose per gram (ID/g) and 16.7 ± 2.2% ID/g, respectively), whereas uptake of (111)In-D2B F(ab')2 and (111)In-D2B Fab fragments peaked at 24 h p.i. (12.1 ± 3.0% ID/g and 15.1 ± 2.9% ID/g, respectively). Maximum LNCaP tumor-to-blood ratios were 13.0 ± 2.3 (168 h p.i.), 6.2 ± 0.7 (24 h p.i.), 23.0 ± 4.0 (24 h p.i.) and 4.5 ± 0.6 (168 h p.i.) for (111)In-D2B IgG, (111)In-F(ab')2, (111)In-Fab and (111)In-capromab pendetide, respectively. LNCaP tumors were clearly visualized with microSPECT with all antibody formats. This study demonstrates the feasibility of D2B IgG, F(ab')2 and Fab fragments for targeting PSMA-expressing prostate cancer xenografts.

A Novel 111In-Labeled Anti–Prostate-Specific Membrane Antigen Nanobody for Targeted SPECT/CT Imaging of Prostate Cancer

“…More importantly, a further drop in renal uptake to 3 %ID/g was observed at 4 h after injection, without loss of tumor targeting. In comparison, these renal uptake values in mice were superior to those found with other PSMA tracers: 100 %ID/g for 68 Ga-HBED-CC-PSMA (1 h) (27) and 111 In-D 2 B-Fab fragments (4 h) (20). Kidney uptake of 78 and 36 %ID/g was reported for 123 I-MIP-1095 and 123 I-MIP-1072 (4 h), respectively (28).…”

“…Kidney uptake of 78 and 36 %ID/g was reported for 123 I-MIP-1095 and 123 I-MIP-1072 (4 h), respectively (28). Tumor-toblood and tumor-to-muscle ratios obtained with 111 In-JVZ-007-cys at 4 h after injection were superior to those obtained with 111 In-D 2 B-Fab fragments (20) and comparable to those obtained with 123 I-MIP-1095, in LNCaP xenograft mice (4 h) (28). The novel method described here for production and site-specific labeling of cys-tagged Nanobodies could have a significant impact for the clinical implementation of a wide range of Nanobodies.…”

“…In parallel to these developments, alternative strategies have been pursued using smaller variants of mAb, such as antigenbinding fragments (Fab) and F(ab9) 2 (20), and minibodies or diabodies (21,22), aiming to circumvent the long circulation time of mAb. These antibody fragments have shown fast target recognition and rapid blood clearance but also show unspecific accumulation in the liver and kidneys.…”

In vivo imaging with antibodies and engineered fragments

“…Comparisons of the pharmacokinetics and targeting of intact and antibody fragments (enzymatically-derived and recombinant) have been conducted; recent examples include targeted imaging of prostate-specific membrane antigen (PSMA) using 111 In-radiolabeled F(ab′) 2 and Fab (Fragment antigen binding) fragments, and 89 Zr-labeled minibodies and diabodies with small animal SPECT or PET (Lütje et al, 2014c; Viola-Villegas et al, 2014). Continued interest in smaller antibody fragments and protein scaffolds is evidenced by several imaging studies with nanobodies (Bannas et al, 2014; De Vos et al, 2014; Massa et al, 2014) and affibodies (Kim et al, 2014; Strand et al, 2014; Zielinski et al, 2012).…”

Monoclonal Antibodies for the Treatment of Cancer

“…This agent is administered to patients with metastatic colorectal cancer to view the extent of metastatic development (39-42); (ii) Ibritumomab tiuxetan is a murine MAB which is labeled with yttrium 90 or Indium 111. These radioactive agents are used for the treatment of patients with non-Hodgkin's lymphoma and often used together with Rituximab which was discussed above (43-45); (iii) Capromab pendetide, a murine MAB, targets prostate membranes and is used to diagnose prostate cancer or determine the extent of cancer eradication following prostatectomy (46)(47)(48); (iv) Tositumomab is a MAB labeled with iodine 131 and is used to treat patients with non-Hodgkin's lymphoma who are unresponsive to standard chemotherapy (49)(50)(51)(52) .…”