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Biomedical subjects

Andrew M Scott

Publications and source records attributed to Andrew M Scott.

At least 19 recordsLinked to original sources
PubMed2026

A Phase I and Biodistribution Study of Ifabotuzumab, a Humanized Agonistic EphA3-Targeted Antibody, in Patients with Recurrent Glioblastoma.

PURPOSE: To conduct a phase I and biodistribution study of the EphA3 antibody ifabotuzumab and zirconium-89-labeled ifabotuzumab (89Zr-ifabotuzumab) in patients with glioblastoma (GBM). PATIENTS AND METHODS: This multisite study was conducted in adults with recurrent GBM whose tumors were measurable according to Response Assessment in Neuro-Oncology (RANO) criteria and whose Eastern Cooperative Oncology Group performance status was 0 to 1. Patients underwent a biodistribution study with PET scans with 89Zr-ifabotuzumab, followed by three infusions of ifabotuzumab at either 3.5 or 5.25 mg/kg before undergoing a second study with 89Zr-ifabotuzumab PET scans. Resected patient diagnostic tumor samples were collected for multiplex immunofluorescence and spatial transcriptomics analyses. RESULTS: Twelve patients were recruited, of which six were treated with 3.5 mg/kg and six with 5.25 mg/kg of ifabotuzumab. 89Zr-ifabotuzumab and associated PET scanning were well tolerated, as was ifabotuzumab. There were no objective responses, but one patient had prolonged stable disease. In addition, two patients showed changes in peritumor edema that were suggestive of modulation of tumor vasculature. 89Zr-ifabotuzumab scans showed highly specific tumor uptake in all patients concordant with disease sites on MRI and PET imaging, without evidence of nonspecific binding. Spatial transcriptomics and immunofluorescence analyses of the patient's archival tissue specimens showed that EphA3 was expressed in the tumor microenvironment in all patients and tumor cells with different transcriptional states. CONCLUSIONS: Targeting EphA3 with ifabotuzumab in patients with GBM is safe and attractive, showing chronologic stable expression across both tumor compartments (particularly in cells with a mesenchymal phenotype) and nontumor compartments (particularly the vascular compartment) with evidence of target modulation.

Humans↗
PubMed2006

HER2-specific T-cell immune responses in patients vaccinated with truncated HER2 protein complexed with nanogels of cholesteryl pullulan.

PURPOSE: We developed a complex of tumor antigen protein with a novel nanoparticle antigen delivery system of cholesteryl pullulan (CHP). To target HER2 antigen, we prepared truncated HER2 protein 1-146 (146HER2) complexed with CHP, the CHP-HER2 vaccine. We designed a clinical study to assess the safety of the vaccine and HER2-specific T-cell immune responses measured by the newly developed enzyme-linked immunospot assay with mRNA-transduced phytohemagglutinin-stimulated CD4(+) T cells in HLA-A2402-positive patients with therapy-refractory HER2-expressing cancers. EXPERIMENTAL DESIGN: Nine patients with various types of solid tumors were enrolled. Each patient was s.c. vaccinated biweekly with 300 microg of CHP-HER2 vaccine for three times followed by booster doses. HER2-specific T-cell responses were evaluated by enzyme-linked immunospot assay by targeting autologous phytohemagglutinin-stimulated CD4(+) T cells transduced with 146HER2-encoding mRNA to cover both identified peptides and unknown epitopes for MHC class I and class II that might exist in the sequence of the vaccine protein. RESULTS: CHP-HER2 vaccine was well tolerated; the only adverse effect was grade 1 transient skin reaction at the sites of vaccination. HER2-specific CD8(+) and/or CD4(+) T-cell immune responses were detected in five patients who received four to eight vaccinations, among whom both T-cell responses were detected in these patients. In four patients with CD8(+) T-cell responses, two patients reacted to previously identified HER2(63-71) peptide and the other two reacted only to 146HER2 mRNA-transduced cells. CONCLUSIONS: CHP-HER2 vaccine was safe and induced HER2-specific CD8(+) and/or CD4(+) T-cell immune responses.

Adult↗
PubMed2006

The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478 increases the formation of inactive untethered EGFR dimers. Implications for combination therapy with monoclonal antibody 806.

The epidermal growth factor receptor (EGFR) has at least two fundamental conformations: an inactive tethered conformation and an active untethered, ligand-bound "back-to-back" dimer, which may be part of an oligomeric complex. Monoclonal antibody (mAb) 806 is an EGFR-specific antibody that only binds a transitional form of the receptor after it untethers but before forming the back-to-back, ligated, active oligomer. We have shown that AG1478, a tyrosine kinase inhibitor of the EGFR, synergistically inhibits the growth of tumors overexpressing EGFR when used in combination with mAb 806 but the mechanism for this was not elucidated (Johns, T. G., Luwor, R. B., Murone, C., Walker, F., Weinstock, J., Vitali, A. A., Perera, R. M., Jungbluth, A. A., Stockert, E., Old, L. J., Nice, E. C., Burgess, A. W., and Scott, A. M. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 15871-15876). We now show that AG1478 increases binding of mAb 806 to the cell surface through two distinct mechanisms: an immediate effect on the conformation of EGFR and a longer term increase in cell surface under-glycosylated EGFR, an event known to increase mAb 806 reactivity. Cross-linking studies demonstrated the presence of spontaneously occurring mAb 806-reactive dimers on the surface of cells overexpressing EGFR, which are rapidly increased by AG1478. Because they react with mAb 806, these dimers must exist in a conformation distinct from the ligated back-to-back dimer. Indeed, we detected similar dimers in 293T cells expressing the EGFR lacking the small dimerization/activation arm essential to the formation of the back-to-back dimer. Thus, some of the EGFR on the cell surface of cancer cells must exist as an untethered dimer that adopts a previously unreported conformation that is inactive. This information was used to optimize the therapeutic synergy between mAb 806 and AG1478 in a xenograft model.

Animals↗
PubMed2006

Evaluating brain activity in obsessive-compulsive disorder: preliminary insights from a multivariate analysis.

Obsessive-compulsive disorder (OCD) has been linked to a dysfunction of brain corticostriatal networks, although functional imaging studies of OCD rarely apply network-sensitive analysis methods. In this study, we compared a univariate and a multivariate analysis of PET data in OCD patients and healthy subjects; the latter approach was considered more suitable for characterizing functional networks of brain activity. Although both methods suggested there was abnormal corticostriatal activity in OCD patients, the nature, extent and magnitude of this activity was clearly enhanced by the multivariate approach. Implications for the analysis of such studies are discussed.

Adult↗
PubMed2006

Relationship of hepatic functional imaging to irinotecan pharmacokinetics and genetic parameters of drug elimination.

PURPOSE: The marked variability of irinotecan (Ir) clearance warrants individualized dosing based on hepatic drug handling. The aims of this trial were to identify parameters from functional hepatic nuclear imaging (HNI) that correlate with (1) Ir pharmacology, and (2) single-nucleotide polymorphisms (SNPs) for the ABCB1 (P-glycoprotein) and UGT-1A1 genes, known to influence Ir handling. METHODS: Patients underwent genotyping for ABCB1 SNPs and UTUGT-1A1*28 carriage and HNI with 99mTc-DIDA (acetanilidoiminodiacetic acid)/99mTc-DISIDA (disofenin) and MIBI (99mTc-sestamibi) scans, probes for biliary transport proteins ABCC1 and -2, and ABCB1 function. HNI data were analyzed by noncompartmental and deconvolutional analysis to provide hepatic extraction and biliary excretion parameters. Patients received Ir, fluorouracil, and folinic acid using a weekly x2, every-3-weeks schedule. Plasma was taken for Ir and SN-38 analysis on day 1, cycle 1. RESULTS: Of the 21 patients accrued, Ir pharmacokinetics data were obtained from 16 patients. 99mTc-DIDA/DISIDA percent retention at 1 hour (1-hour RET) correlated to baseline serum bilirubin (P = .008). Both 99mTc-DIDA/DISIDA and MIBI 1-hour RET correlated with SN-38 area under the curve (AUC; P < .01). On multiple regression analysis, SN-38 AUC = -215 + 18.68 x bilirubin + 4.27 x MIBI 1-hour RET (P = .009, R2 = 44.2%). HNI parameters did not correlate with Ir toxicity or UGT1A1*28 carriage. MIBI excretion was prolonged in patients with the ABCB1 exon 26 TT variant allele relative to wild-type (P = .015). CONCLUSION: Functional imaging of hepatic uptake and excretory pathways may have potential to predict Ir pharmacokinetics. Evaluation of a larger cohort as well as polymorphisms in other biliary transporters and UGT1A1 alleles is warranted.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2006

Xenografting tumour beneath the renal capsule using modern surgical equipment.

INTRODUCTION: The growth of human tumours under the renal capsule in animal models has been performed in the past. However, the use of modern surgical equipment has not always been translated into the laboratory. We report on a novel method for human renal tumour transplants using an automated biopsy gun to obtain tumour tissue and an epidural needle with introducer to easily deploy the grafts under the renal capsule. METHODS: Nude mice had human xenografted tumours grown subcutaneously after implantation of cells from culture. Tumours were then biopsied using a 16-gauge automated biopsy gun. Digital calipers were used to measure a 2-mm segment of the biopsy core that was cut and placed inside a hollow needle (epidural needle). The needle was placed under the renal capsule and the trocar introduced to deploy the graft beneath the capsule with minimal trauma. Further groups had tumour harvested similarly by automated biopsy gun but had the implants placed subcutaneously for comparison. RESULTS: Tumour grafts were established in 90% of grafted kidneys in this renal subcapsular model (229.68 +/- 118.32 mm(3); mean +/- 95% CI) which compared favourably to the subcutaneous model (163.81 +/- 43.3 mm(3)). Grafts were confirmed by direct observation and histology. CONCLUSION: Modern surgical equipment may be utilised to allow tumour transplantation to be precise, with an identifiable and reproducible tumour volume deployed. Surgical researchers and laboratory-based scientists need to embrace new techniques and utilise them to improve models. This model may be adapted to many situations in oncologic research involving xenografting.

Animals↗
PubMed2006

Safety, pharmacokinetic and dosimetry evaluation of the proposed thrombus imaging agent 99mTc-DI-DD-3B6/22-80B3 Fab'.

PURPOSE: (99m)Tc-DI-DD-3B6/22-80B3 (Thromboview, hereafter abbreviated to (99m)Tc-DI-80B3 Fab') is a humanised, radiolabelled monoclonal antibody Fab' fragment with high affinity and specificity for the D-dimer domain of cross-linked fibrin. The purpose of this study was to evaluate the safety, pharmacokinetics and dosimetry of four increasing doses of (99m)Tc-DI-80B3 Fab' in healthy volunteers. METHODS: Thirty-two healthy volunteers (18-70 years; 16 male, 16 female) received a single intravenous injection of 0.5, 1.0, 2.0 or 4.0 mg of (99m)Tc-DI-80B3 Fab'. Safety outcomes (vital signs, electrocardiography, haematology, biochemistry, adverse events and development of human anti-human antibodies) were assessed up to 30 days post injection. Blood and urine samples were collected up to 48 h post injection. Gamma camera images were acquired at 0.5, 1, 2, 4, 6 and 24 h post injection. Dosimetry was performed using standard MIRD methodology. RESULTS: No adverse events considered to be drug related were observed. Human anti-human antibody was not detectable in any subject during the follow-up period. (99m)Tc-DI-80B3 Fab' had a rapid initial plasma clearance (t (1/2)alpha=1 h). The pharmacokinetic profile of the Fab' fragment was generally linear across the four dose cohorts. By 24 h, 30-35% of the administered radioactivity appeared in the urine. There was marked renal accumulation with time, but no specific uptake was identified within other normal tissues. The effective dose was 9 mSv/750 MBq. CONCLUSIONS: (99m)Tc-DI-80B3 Fab' is well tolerated, is rapidly cleared and exhibits clinically acceptable dosimetry-characteristics well suited to a potential thrombus imaging agent.

Adolescent↗
PubMed2006

Novel imaging techniques in melanoma.

Cutaneous melanoma is one of the most deadly malignancies. Although it accounts for approximately 4% of all cancer cases, it ac-counts for approximately 79% of skin cancer-related deaths. In the past few years, the nuclear medicine platform used in the management of melanoma has extended to biochemical and structural imaging. In clinical practice, integrated positron emission tomography/CT devices allow anatomic and metabolic characterization of meta-static disease in a single study. Similarly, more accurate localization of sentinel nodes in a 3-D space now is feasible with hybrid single photon emission CT/CT system. In translational research, [18F]fluorodeoxyglucose probes have been designed to optimize the detection of melanoma tumor sites in vivo.

Diagnostic Imaging↗
PubMed2006

A phase I radioimmunolocalization trial of humanized monoclonal antibody huA33 in patients with gastric carcinoma.

In order to determine the in vivo characteristics of huA33, an open label dose escalation biopsy-based phase I clinical trial and radioimmunolocalization study were conducted with a complement determinant region-grafted humanized monoclonal antibody against the A33 antigen in patients with gastric carcinoma. Thirteen patients were entered onto one of four dose levels (1.0, 2.0, 5.0 or 10.0 mg/m(2)). Patients with locally advanced (UICC-TNM [International Union Against Cancer-tumor, node, metastasis] stage over 2 but resectable at clinical diagnosis) gastric carcinoma received a single infusion of (131)I-huA33 1 week prior to surgery. Adverse events were monitored, and imaging studies with gamma camera plus ex vivo scintigraphy of the resected specimen, biodistribution study by dosimetry analysis of the biopsied and resected tissues, and immunohistochemical analysis were carried out and evaluated. No dose-limiting toxicity was observed during the trial. Therefore, the maximum tolerated dose was not reached. Although cancer tissues with + intensity and <25% extent by immunostaining in biopsied frozen sections did not show positive imaging or postoperative dosimetry findings, cancers with ++ or +++ intensity or wide (>25%) extent by frozen and paraffin sections in the biopsied specimen showed positive ex vivo tumor images and positive antigen expression in resected gastric cancer specimens, and the biodistribution analysis showed tumor uptake of (131)I-huA33. In conclusion, humanized monoclonal antibody huA33 demonstrated selective localization to gastric cancer that expressed A33 antigen strongly. These excellent targeting characteristics of huA33 indicate potential for targeted therapy of advanced gastric cancer that is refractory to cytotoxic therapy, and could also be exploitable for curatively resected early gastric cancer in an adjuvant setting.

Aged↗
PubMed2006

Correlation of hypoxic cell fraction and angiogenesis with glucose metabolic rate in gliomas using 18F-fluoromisonidazole, 18F-FDG PET, and immunohistochemical studies.

UNLABELLED: PET offers a noninvasive means to assess neoplasms, in view of its sensitivity and accuracy in staging tumors and potentially in monitoring treatment response. The aim of this study was to evaluate newly diagnosed primary brain tumors for the presence of hypoxia, as indicated by the uptake of 18F-fluoromisonidazole (18F-FMISO) and to examine the relationship of hypoxia to the uptake of 18F-FDG and molecular markers of hypoxia. METHODS: Seventeen patients with suspected primary glioma were enrolled prospectively in this study. Sixteen patients had histology, with 2 having metastatic disease. All patients had PET studies with 18F-FMISO and 18F-FDG and MRI studies. Immunohistochemistry was undertaken with tumor markers of angiogenesis and hypoxia. Patients were monitored for disease progression and statistical analysis of data was performed. RESULTS: Of the 14 patients with histology, 8 died with a median time of 16 mo (range, 2-30 mo) until death. Of those who died, 7 had positive and 1 had negative 18F-FMISO uptake. 18F-FMISO uptake was observed in all high-grade gliomas but not in low-grade gliomas. A significant relationship was found between 18F-FDG or 18F-FMISO uptake and expression of VEGF-R1 and Ki67 expression. Other immunohistochemical markers demonstrated a trend toward increased uptake but none was significant. CONCLUSION: 18F-FMISO PET provides a noninvasive assessment of hypoxia in glioma and was prognostic for treatment outcomes in the majority of patients. 18F-FMISO PET may have a role not only in directing patients toward targeted hypoxic therapies but also in monitoring response to such therapies.

Adult↗
PubMed2006

Enhanced efficacy of 90Y-radiolabeled anti-Lewis Y humanized monoclonal antibody hu3S193 and paclitaxel combined-modality radioimmunotherapy in a breast cancer model.

UNLABELLED: Radioimmunotherapy (RIT) of solid tumor is often limited in efficacy because of restrictions in achieved tumor dose. In an effort to overcome this, the combination of RIT with other therapeutic modalities was investigated in an animal model of breast carcinoma. The rationale for this combined-modality RIT (CMRIT) was to increase the therapeutic efficacy of RIT through the use of paclitaxel to arrest cells in the radiosensitive G(2)/M phase of the cell cycle. METHODS: In this study, the biodistribution and therapeutic efficacy of (90)Y-radiolabeled humanized anti-Lewis Y hu3S193 monoclonal antibody ((90)Y-hu3S193) RIT in combination with paclitaxel chemotherapy was explored in a Lewis Y-expressing MCF-7 tumor xenografted BALB/c nude mouse model of breast cancer. RESULTS: Biodistribution studies demonstrated excellent tumor targeting and limited normal tissue uptake by (90)Y-hu3S193. A therapeutic study with established tumors assessed (90)Y-hu3S193 as a single agent and demonstrated significant antitumor effects in all animals receiving a single intravenous 1.85 or 3.70 MBq dose of this treatment compared with phosphate-buffered saline placebo controls (P = 0.0008 vs. P < 0.0001). Complete responses were observed in all animals in the 3.70 MBq study arm for the duration of the study. Single-dose (90)Y-hu3S193 plus paclitaxel (600 microg) CMRIT displayed improved efficacy over single-modality therapies, with a significant difference (P < 0.0001) between the mean percentage change in tumor volume in mice receiving 0.46 MBq (90)Y-hu3S193 alone and when combined with 600 mug paclitaxel. CONCLUSION: The significant efficacy of (90)Y-hu3S193 and paclitaxel CMRIT at low radiation doses in this model of breast carcinoma indicates its therapeutic potential and warrants further investigation into this promising therapeutic approach.

Animals↗
PubMed2006

Role of nuclear medicine in the management of cutaneous malignant melanoma.

Malignant melanoma of the skin is one of the most lethal cancers. The disease may spread either locally or regionally and to distant sites through predictable or unpredictable metastatic pathways. Accurate staging and restaging of disease are required for appropriate treatment decision making. Routine protocols based on clinical examinations and traditional radiologic evaluations are not cost-effective for the detection of systemic disease. In the last decade, nuclear medicine techniques, such as lymphoscintigraphy-directed lymphatic mapping and sentinel lymphadenectomy and (18)F-FDG PET, have played key roles in nodal and distant staging of melanoma. More recently, anatomic-functional imaging has been improved with the development of integrated PET/CT devices or combined SPECT/CT systems. (18)F-FDG-sensitive intraoperative probes have been specifically designed to detect small nodal and visceral metastases from melanoma and may become important tools for the cancer surgeon. In this article, we review the role of nuclear medicine in the assessment of malignant melanoma.

Humans↗
PubMed2006

Lack of correlation of hypoxic cell fraction and angiogenesis with glucose metabolic rate in non-small cell lung cancer assessed by 18F-Fluoromisonidazole and 18F-FDG PET.

UNLABELLED: PET offers a noninvasive means to assess neoplasms, in view of its sensitivity and accuracy in staging tumors and potentially in monitoring treatment response. The aim of this study was to evaluate newly diagnosed non-small cell lung cancer (NSCLC) for the presence of hypoxia, as indicated by the uptake of (18)F-Fluoromisonidazole ((18)F-FMISO), and to examine the relationship of hypoxia to the uptake of (18)F-FDG, microvessel density, and other molecular markers of hypoxia. METHODS: Twenty-one patients with suspected or biopsy-proven NSCLC were enrolled prospectively in this study. All patients had PET studies with (18)F-FMISO and (18)F-FDG. Seventeen patients subsequently underwent surgery, with analysis performed for tumor markers of angiogenesis and hypoxia. RESULTS: In the 17 patients with resectable NSCLC (13 men, 4 women; age range, 51-77 y), the mean (18)F-FMISO uptake in tumor was significantly lower than that of (18)F-FDG uptake (P < 0.0001) and showed no correlation with (18)F-FDG uptake (r = 0.26). The mean (95% confidence interval [CI]) (18)F-FMISO SUV(max) (maximum standardized uptake value) was 1.20 [0.95-1.45] compared with the mean [95% CI] (18)F-FDG SUV(max) of 5.99 [4.62-7.35]. The correlation between (18)F-FMISO uptake, (18)F-FDG uptake, and tumor markers of hypoxia and angiogenesis was poor. A weakly positive correlation between (18)F-FMISO and (18)F-FDG uptake and Ki67 was found. CONCLUSION: The hypoxic cell fraction of primary NSCLC is consistently low, and there is no significant correlation in NSCLC between hypoxia and glucose metabolism in NSCLC assessed by (18)F-FDG. These findings have direct implications in understanding the role of angiogenesis and hypoxia in NSCLC biology.

Aged↗
PubMed2005

Adoptive transfer of T cells modified with a humanized chimeric receptor gene inhibits growth of Lewis-Y-expressing tumors in mice.

In this study, human T cells were provided with a reactivity against the Lewis-Y (Le(Y)) carbohydrate antigen, which is overexpressed on 70% of epithelial-derived tumors, but not normally recognized by T cells. Antitumor reactivity was achieved by transduction of T cells with a gene encoding a cell-surface chimeric receptor composed of single-chain anti-Le(Y) antibody linked to an enhanced cytoplasmic signaling domain made up of CD28 and CD3-zeta. Importantly, the single-chain antibody was humanized to try to reduce potential problems of human anti-mouse antibody responses in patients receiving chimeric receptor-modified T cells in future clinical trials. T cells expressing the chimeric receptor were demonstrated to secrete cytokines and proliferate in response to receptor ligation and lysed Le(Y+) tumors in vitro. Another aspect of this study was the finding that no activity was observed against normal tissue, as represented by autologous neutrophils that express low levels of Le(Y). Significantly, systemic delivery of anti-Le(Y) T cells dramatically inhibited established s.c. human ovarian OVCAR-3 tumors (a recognized difficult model to treat) in mice. Finally, we demonstrated that anti-Le(Y) T cells preferentially expanded or accumulated in the tumor compared with control empty vector T cells, thereby providing mechanistic insight into the specific antitumor response. This study supports the use of humanized gene-modified T cells as a potential therapy for Le(Y+) malignancies.

Adoptive Transfer↗
PubMed2005

300 W quasi-continuous-wave diffraction-limited output from a diode-pumped Nd:YAG master oscillator power amplifier with fiber phase-conjugate stimulated Brillouin scattering mirror.

A master oscillator power amplifier system comprising a cw Nd:YAG master oscillator, a quasi-cw diode-pumped power amplifier, and a fiber-based stimulated Brillouin scattering phase-conjugate mirror is reported. A 12-pass amplifier configuration is employed to achieve high gain in a small-length slab amplifier. Residual and pump-induced optical inhomogeneities in the slab are corrected by the fiber phase conjugator to achieve diffraction-limited output beam quality. 300 W quasi-cw output and a maximal attainable gain of approximately 150 for the system are obtained.

Journal Article↗
PubMed2005

Enhanced efficacy of radioimmunotherapy with 90Y-CHX-A''-DTPA-hu3S193 by inhibition of epidermal growth factor receptor (EGFR) signaling with EGFR tyrosine kinase inhibitor AG1478.

PURPOSE: Monoclonal antibodies and tyrosine kinase inhibitors specific for the epidermal growth factor receptor (EGFR) have been shown to enhance the effect of external beam radiation on EGFR-positive tumors. The effect of EGFR signaling abrogation by EGFR tyrosine kinase inhibitor on the efficacy of radioimmunotherapy has not been reported previously. This study investigated the effect of EGFR tyrosine kinase inhibition on the efficacy of radioimmunotherapy in a human cancer xenograft model. EXPERIMENTAL DESIGN: The humanized anti-Lewis Y antibody hu3S193 and the EGFR tyrosine kinase inhibitor AG1478 were studied. BALB/c nude mice were engrafted with A431 squamous carcinoma cells. Initial biodistribution properties of the 90Y-CHX-A''-DTPA-hu3S193 were evaluated in this model. In therapy experiments, cohorts of four to five xenografted mice were treated with saline as placebo, 0.4 mg AG1478 i.p. (six doses over 2 weeks), single i.v. injections of unlabeled hu3S193, or 90Y-CHX-A''-DTPA-hu3S193 (12.5, 25, 50, or 100 microCi). The combination of 0.4 mg AG1478 i.p. and 25 microCi 90Y-CHX-A''-DTPA-hu3S193 i.v. was subsequently evaluated in the A431 model. RESULTS: 90Y-CHX-A''-DTPA-hu3S193 retained excellent immunoreactivity after radiolabeling. The biodistribution study showed excellent uptake in tumor (90.33 +/- 38.84%ID/g) peaking at 24 to 72 hours after injection and with prolonged retention. 90Y-CHX-A''-DTPA-hu3S193 significantly inhibited A431 xenograft growth at 25, 50, and 100 microCi doses. The combination of 0.4 mg AG1478 with a single dose of 25 microCi 90Y-CHX-A''-DTPA-hu3S193 resulted in a significant enhancement of efficacy compared with either agent alone (P = 0.013). CONCLUSIONS: The efficacy of radioimmunotherapy with 90Y-CHX-A''-DTPA-hu3S193 is significantly enhanced by EGFR tyrosine kinase inhibitor AG1478. Further investigations of dosing regimens using EGFR tyrosine kinase inhibitors and radioimmunotherapy in the treatment of EGFR expressing tumors are warranted.

Animals↗