Peptide-receptor imaging and therapy with radiolabeled somatostatin analogs such as Ga-DOTA-TATE and Lu-DOTA-TATE have become an effective treatment option for SSTR-positive neuroendocrine tumors. The purpose of this study was to evaluate the correlation of somatostatin receptor-2 (SSTR2) expression with Ga-DOTA-TATE uptake and Lu-DOTA-TATE therapy in neuroblastoma (NB) xenograft models. We demonstrated variable SSTR2 expression profiles in eight NB cell lines.
View Article and Find Full Text PDFHeterodimerization of EGFR with HER2 coexpressed in breast cancer (BC) promotes tumor growth, and increased EGFR expression is associated with trastuzumab resistance. Our aim was to construct Cu-labeled bispecific radioimmunoconjugates (bsRIC) composed of trastuzumab Fab, which binds HER2 linked through a polyethylene glycol (PEG) spacer to EGF, and to compare their pharmacokinetic, biodistribution, and tumor imaging characteristics by positron-emission tomography (PET). bsRICs were generated by linking maleimide modified trastuzumab Fab with thiolated EGF through a thioether bond.
View Article and Find Full Text PDFPurpose: Most effective antitumor therapies induce tumor cell death. Non-invasive, rapid and accurate quantitative imaging of cell death is essential for monitoring early response to antitumor therapies. To facilitate this, we previously developed a biocompatible necrosis-avid near-infrared fluorescence (NIRF) imaging probe, HQ4, which was radiolabeled with Indium-chloride (In-Cl) via the chelate diethylene triamine pentaacetic acid (DTPA), to enable clinical translation.
View Article and Find Full Text PDFWe previously reported that In-labeled pertuzumab imaged trastuzumab (Herceptin)-mediated changes in HER2 expression preclinically in breast cancer tumors. To advance In-labeled pertuzumab to a Phase I/II clinical trial, a kit was designed for preparing this agent in a form suitable for human administration. Unit-dose kits containing pertuzumab modified with 2-(4-isothiocyanatobenzyl)-diethylenetriaminepentaacetic acid (BzDTPA) were prepared that labeled to high efficiency (>90%) with In and met specifications for pharmaceutical quality.
View Article and Find Full Text PDFIntroduction: Our aim was to conduct a Phase I clinical trial to determine the feasibility of intraoperative detection of tumor margins in HER2 positive breast carcinoma using a hand-held γ-probe following administration of (111)In-DTPA-trastuzumab Fab fragments. Accurate delineation of tumor margins is important for preventing local recurrence.
Methods: Six patients with HER2-positive in situ or invasive ductal carcinoma were administered 74MBq (0.
Unlabelled: Heterodimerization of human epidermal growth factor receptor 2 (HER2) with HER3 initiates aberrant downstream growth-signaling pathways in tumors. Our objective was to construct bispecific radioimmunoconjugates (bsRICs) that recognize HER2 and HER3 and evaluate their ability to image tumors in athymic mice that express one or both receptors using small-animal SPECT/CT.
Methods: bsRICs were constructed by reacting the maleimide-derivatized trastuzumab Fab fragments that bind HER2 with a thiolated form of the HER3-binding peptide of heregulin-β1 (HRG) with or without a 12- or 24 mer polyethylene glycol (PEG) spacer.
Purpose: To study the effects of backbone composition and charge of biotin-functionalized metal-chelating polymers (Bi-MCPs) for (111)In complexed to streptavidin (SAv)-trastuzumab Fab fragments on tumor and normal tissue localization.
Methods: Bi-MCPs were synthesized with a polyacrylamide [Bi-PAm(DTPA)(40)], polyaspartamide [Bi-PAsp(DTPA)(33)] or polyglutamide [Bi-PGlu(DTPA)(28)] backbone and harboured diethylenetriaminepentaacetic acid (DTPA) chelators for (111)In. Bi-PAm(DTPA)(40) had a net negative charge; Bi-PAsp(DTPA)(33) and Bi-PGlu(DTPA)(28) were zwitterionic with a net neutral charge.
Background: Our objective was to compare 111In- or 64Cu-DOTA-trastuzumab Fab fragments for imaging small or large s.c. tumor xenografts in athymic mice that display a wide range of human epidermal growth factor receptor-2 (HER2) expression using microSPECT/CT or microPET/CT.
View Article and Find Full Text PDFIntroduction: The aim of the study was to evaluate the uptake of [(18)F]-1-deoxy-1-fluoro-scyllo-inositol ([(18)F]-scyllo-inositol) in human breast cancer (BC) and glioma xenografts, as well as in inflammatory tissue, in immunocompromised mice. Studies of [(18)F]-2-fluoro-2-deoxy-d-glucose ([(18)F]-FDG) under the same conditions were also performed.
Methods: Radiosynthesis of [(18)F]-scyllo-inositol was automated using a commercial synthesis module.
Introduction: The human epidermal growth factor receptor-2 (HER2) gene is amplified in 25% of invasive breast cancers, and receptor overexpression has been noted in up to 60% of early stages of the disease [ductal carcinoma in situ (DCIS)]. Preclinical studies have revealed high tumor/blood ratios (>27:1) for (111)In-labeled Fab fragments of the HER2 monoclonal antibody, trastuzumab (Herceptin) ((111)In-DTPA-trastuzumab Fab) at 72 h pi in athymic mice bearing subcutaneous human breast cancer xenografts. Our aim in this study was to formulate a kit for preparation of (111)In-DTPA-trastuzumab Fab injection under good manufacturing practice (GMP) conditions suitable for human administration in a Phase I clinical trial of imaging and radioimmunoguided surgery (RIGS) of HER2-positive breast cancer.
View Article and Find Full Text PDFUnlabelled: Breast cancers (BCs) with high human epidermal growth factor receptor type 2 (HER2) expression are most likely to respond to trastuzumab; however, the mechanisms of action of trastuzumab are complex and there are no established biomarkers to accurately monitor treatment outcome in individual patients. Therefore, our aim was to determine, in human BC xenografts in athymic mice treated with trastuzumab, whether there were any changes in (18)F-FDG uptake that were associated with response to the drug and that could have utility in monitoring response in patients.
Methods: Baseline tumor uptake of (18)F-FDG was measured in mice with MDA-MB-361 HER2-overexpressing xenografts and MDA-MB-231 xenografts with low HER2 expression by small-animal PET imaging on day 0.
Unlabelled: Pertuzumab is a HER2 dimerization inhibitor that binds to an epitope unique from that of trastuzumab. Our objective was to determine whether SPECT with (111)In-diethylenetriaminepentaacetic acid-pertuzumab ((111)In-DTPA-pertuzumab) could sensitively detect an early molecular response to trastuzumab manifested by HER2 downregulation and a later tumor response revealed by a decreased number of HER2-positive viable tumor cells.
Methods: Changes in HER2 density in SKBr-3 and MDA-MB-361 BC cells exposed to trastuzumab (14 microg/mL) in vitro were measured by saturation binding assays using (111)In-DTPA-pertuzumab and by confocal immunofluorescence microscopy and flow cytometry with fluorescein isothiocyanate-labeled HER2/neu antibodies.
Purpose: The purpose of the study was to investigate the associations between uptake of (111)In-DTPA-trastuzumab, tumour HER2 density and response to trastuzumab (Herceptin) of human breast cancer (BC) xenografts in athymic mice.
Materials And Methods: The tumour uptake of (111)In-DTPA-trastuzumab in athymic mice bearing BC xenografts with increasing HER2 density (0 to 3+) was evaluated. Specific uptake ratios were established in biodistribution (SUR) and imaging studies (ROI-SUR) using (111)In-labeled mouse IgG ((111)In-DTPA-mIgG).
Unlabelled: The Auger electron-emitting radiopharmaceutical 111In-diethylenetriaminepentaacetic acid human epidermal growth factor (111In-DTPA-hEGF) binds the epidermal growth factor receptor (EGFR), is internalized, and translocates to the nucleus. The purpose of this study was to investigate the relationship between EGFR expression, DNA damage, and cytotoxicity in cells exposed to 111In-DTPA-hEGF.
Methods: Breast cancer cell lines with a range of EGFR expression levels were exposed to 111In-DTPA-hEGF or gamma-radiation.
Introduction: Our objective was to evaluate the tumor and normal tissue distribution and nuclear importation properties of [(111)In]-mouse IgG (mIgG) conjugated to tat peptides (GRKKRRQRRRPPQGYG) in athymic mice with subcutaneous BT-474 human breast cancer xenografts.
Methods: Tumor and normal tissue uptake was compared after intravenous (iv) or intratumoral injection of [(111)In]-mIgG-tat and [(111)In]-mIgG. Area under the curve (AUC) was estimated for blood, liver, spleen, kidneys and tumor.
Unlabelled: (111)In-DTPA-human epidermal growth factor ((111)In-DTPA-hEGF [DTPA is diethylenetriaminepentaacetic acid]) is an Auger electron-emitting radiopharmaceutical that targets EGF receptor (EGFR)-positive cancer. The purpose of this study was to determine the effect of EGFR inhibition by gefitinib on the internalization, nuclear translocation, and cytotoxicity of (111)In-DTPA-hEGF in EGFR-overexpressing MDA-MB-468 human breast cancer cells.
Methods: Western blot analysis was used to determine the optimum concentration of gefitinib to abolish EGFR activation.
Tumor-associated glycoprotein-72 (TAG-72) is overexpressed in a high percentage of epithelial cancers and has proven useful as a target for imaging and targeted radiotherapy. Our goal was to express a recombinant Fab (rFab) of the TAG-72 monoclonal antibody CC49 in Pichia pastoris and directly compare its tumor and normal tissue uptake and imaging properties with enzymatically generated Fab (eFab). In this study, the genes coding for CC49 Fab were cloned from hybridoma cells and expressed in P.
View Article and Find Full Text PDFPurpose: To evaluate the internalization and nuclear translocation of (123)I-tat-peptide radioimmunoconjugates in MDA-MB-468 breast cancer cells and their ability to interact with the cyclin-dependent kinase inhibitor, p21(WAF-1/Cip-1).
Methods: Peptides [GRKKRRQRRRPPQGYGC] harboring the nuclear-localizing sequence from HIV tat domain were conjugated to anti-p21(WAF-1/Cip-1) antibodies. Immunoreactivity was assessed by Western blot using lysate from MDA-MB-468 cells exposed to EGF to induce p21(WAF-1/Cip-1).
Purpose: We tested the suitability of (99m)Tc-sestamibi to image the inhibition of P-glycoprotein (Pgp)-mediated multidrug resistance in tumor cells and xenografts after antisense treatment and/or inhibition with a novel Pgp modulator WK-X-34.
Procedure: Pgp inhibition was measured by daunorubicin transport assays and fluorescence microscopy in resistant A2780/Adr cells treated with WK-X-34 and antisense. A2780/Adr xenograft mice were dosed with mdr1 antisense oligodeoxynucleotides intratumorally for three days; next, mice were treated with WK-X-34, followed by (99m)Tc-sestamibi injection.
Overexpression of the multidrug resistance proteins P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) results in treatment failure of many malignancies including ovarian cancer. Dual inhibition of Pgp and BCRP may restore the sensitivity of resistant cells to anticancer drugs. We report the synthesis and characterization of a novel anthranilic-acid based Pgp and BCRP modulator, WK-X-34.
View Article and Find Full Text PDFPurpose: Our objective was to study the cellular and nuclear uptake of (123)I-mouse IgG ((123)I-mIgG) linked to peptides [GRKKRRQRRRPPQGYGC] harbouring the membrane-translocating and nuclear import sequences of HIV-1 tat protein.
Methods: Carbohydrates on mIgG were oxidized by NaIO(4), then reacted with a 40-fold excess of peptides. Displacement of binding of anti-mouse IgG (Fab specific; alpha-mFab) to (123)I-mIgG by tat-mIgG or mIgG was compared.
Unlabelled: Our objective was to synthesize a recombinant protein (hnTf-VEGF [VEGF is vascular endothelial growth factor]) composed of VEGF(165) fused through a flexible polypeptide linker (GGGGS)(3) to the n-lobe of human transferrin (hnTf) for imaging angiogenesis. The hnTf domain allowed labeling with (111)In at a site remote from the VEGF receptor-binding domain.
Methods: DNA encoding hnTf, peptide linker (GGGGS)(3), and VEGF(165) genes were cloned into the Pichia pastoris vector pPICZalphaB to generate the pPICZalphaB-hnTF-VEGF plasmid.
Unlabelled: (99m)Tc-sestamibi is a widely used radiopharmaceutical agent for myocardial and oncologic imaging. Because of its unique role as a P-glycoprotein (Pgp)-specific substrate, this compound can be used to examine Pgp functional activity in vitro and in vivo under pathologic conditions. Our objective was to use (99m)Tc-sestamibi as a tool to investigate whether systemic inflammation induced by Escherichia coli lipopolysaccharide (LPS) would affect in vivo Pgp function in the brain, heart, liver, and kidneys of rats.
View Article and Find Full Text PDFTrastuzumab (Herceptin) Fab were prepared by digestion of intact IgG with immobilized papain, derivatized with diethylenetriaminepentaacetic acid (DTPA) and radiolabeled with (111)In. The dissociation constant (Kd) for binding of Fab to HER2/neu-positive SK-BR-3 human breast cancer cells was two- to threefold higher than for intact IgG (14-36 vs. 8-14 nM).
View Article and Find Full Text PDFUnlabelled: Our goal was to design and manufacture a kit under good manufacturing practices (GMP) for the preparation of (111)In-DTPA-hEGF Injection, a novel targeted radiotherapeutic agent for advanced epidermal growth factor receptor (EGFR)-positive breast cancer.
Methods: Human EGF (hEGF) was derivatized with diethylenetriaminepentaacetic acid (DTPA) and then purified by size-exclusion chromatography and ultrafiltration. Kits were prepared by dispensing 0.