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3555Background: MET amp is a well described driver of acquired EGFR antibody (Ab) resistance. Blood-based genomic profiling of cell free (cf)DNA is a safe and efficient means to identify pts with a...

Squamous cell cancer of the head and neck (HNSCC) would seem to be the ideal malignancy for epidermal growth factor receptor (EGFR) inhibition either with antibodies or small molecule tyrosine kinase (TK) inhibitors. EGFR protein is overexpressed in more than 90% of tumors relative to normal tissue, and high expression is associated with poor disease control. Data from preclinical models show at least additive effects of the two classes of EGFR inhibitors when combined with cisplatin, providing rationale for combination therapy. To date, cetuximab has been studied in recurrent HNSCC in combination with cisplatin and platinum plus fluorouracil (FU) as first-line treatment for recurrence and in the setting of platinum refractory disease, whereas the small molecule TK inhibitors have been tested as single agents in the secondor third-line setting. The optimal timing of EGFR inhibitors in the palliation of patients with disease recurrence has not been well defined. HNSCC has the theoretical advantage of providing easily accessible tumor for biopsy, which could facilitate study of the putative effects of molecularly targeted therapies on the complex signaling pathways downstream of the EGFR. Such correlative tissue studies are needed to elucidate EGFR pathway tumor biology and identify predictive markers for better patient selection for these costly therapies. This issue of the Journal of Clinical Oncology contains five articles that provide some insights into these questions and the results of an analysis of the impact of radiotherapy (RT) plus EGFR antibody therapy on quality of life (QoL). QoL is a complex measure, particularly for those not immersed in this field, seemingly with its own terminology, variety of tools, and myriad statistical tests. However, the importance of QoL cannot be underestimated for patients with head and neck cancer. As multimodality therapies are intensified, consideration of QoL in therapeutic decision-making, and in formulating standards of care, is of paramount importance. This issue of JCO contains a report of QoL assessments that were performed as part of the prospective comparison of RT alone to RT plus concurrent cetuximab in patients with locally advanced HNSCC published by Bonner et al. Significant improvements in overall survival and local-regional recurrence-free survival were observed for patients in the cetuximab treatment group without an apparent increase in toxicity. The current paper bolsters those findings through the use of two validated questionnaires (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire C30 and Quality of Life Questionnaire, Head and Neck Module) that address symptom burden and its effect on physical and functional well-being, emotional, and social interactions. No significant differences were found between the two treatments in QoL at baseline or during the course of treatment out to 12 months. In both groups, QoL declined during treatment, with the greatest impact on function due to fatigue, loss of appetite, swallowing difficulty, and sensory problems, and then improved by 8 to 12 months. The authors interpreted this as a positive result. This pattern of decline and then return to baseline by about 12 months confirms data from other head and neck trials as does the observed correlation between global health/QoL and survival. Because a significant difference in local-regional control was reported in the primary paper, one might have postulated that the symptom burden of uncontrolled disease would result in a worse QOL for patients in the control group. In other words, the real goal and indication of a positive outcome should be an improvement in QOL for patients receiving the treatment that afforded them significantly longer survival and disease control, in this case RT plus cetuximab. It is not clear whether the occurrence of more dropouts over time among controls (RT alone) obscured this effect or the questionnaires used were not sensitive enough to detect differences between the treatment groups (not just within treatment groups). The conclusion that QOL was not worse for patients receiving RT plus cetuximab than for those treated with RT alone is, unfortunately, not very satisfying. As advances are made in multimodality therapies, we should seek improvements in QoL that parallel improvements in survival. Two therapeutic trials are reported in this issue. Vermorken et al tested single-agent cetuximab in a multicenter phase II trial enrolling 103 patients with recurrent/metastatic HNSCC that had progressed on platinum-based chemotherapy. In a two-part design, patients were first treated with cetuximab alone until disease progression, and then they were offered continuation of cetuximab with the addition of platinum. The objective response rate (complete plus partial response) for treatment with cetuximab alone was 13% (95% CI, 7 to 21), the disease control rate (complete plus partial plus stable response) was 46% (95% CI, 36 to 56), and the median time to progression (TTP) was 70 days. Of these 103 patients, 53 proceeded to the second part of the trial and received JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 25 NUMBER 16 JUNE 1 2007

654 Background: Guidelines for managing patients with metastatic colorectal cancer (mCRC) were updated in Denmark in 2013, and anti-epidermal growth factor receptor (EGFR) inhibitors were promoted from third-line to first-line treatment for KRAS wildtype mCRC patients. As a result, more patients became eligible for EGFR antibody therapy. Weexamined KRAS testing practice among patients with mCRC who received systemic cancer treatment in Denmark during 2009-2013. Methods: We linked data from several population registries with nationwide coverage - the Danish Cancer Registry, the Danish National Patient Registry, and the Danish National Pathology Registry - to identify patients diagnosed with mCRC (primary or recurrent) between 2009 and 2013, their systemic cancer treatment, and their KRAS testing status. We obtained all KRAS test results through 2014 and calculated proportions of KRAS-tested patients by year of mCRC diagnosis. Results: There were 7,245 mCRC patients, among whom 4,272 (59%) had a record of systemic cancer treatment within 6 months of mCRC diagnosis and were included in the analysis. The proportion of men was 57%; median age at mCRC diagnosis was 67 years (range 20-94 years). Overall, 2,099/4,272 (49%) of the treated mCRC patients had a recorded KRAS test result, with similar proportions for patients with primary and recurrent mCRC. Among patients diagnosed with mCRC in 2009, the proportion with a recorded KRAS test result was 374/900 (42%). Corresponding proportions for patients diagnosed in 2010, 2011, 2012, and 2013 were 411/891 (46%), 457/870 (52%), 430/807 (53%), and 427/804 (53%). Conclusions: Among patients in Denmark diagnosed with mCRC who received systemic cancer treatment, the proportion of patients with a KRAS test result recorded in the Danish National Pathology Registry increased from 2009 to 2013. This may have resulted from increased testing or increased recording, or both.

TPS5600 Background: Standard treatment for locally advanced SCCHN, chemoradiotherapy (CRT), leads to significant acute and long-term morbidity. The demonstration that EGFR antibody (Ab) therapy improves outcome when added to standard RT (Bonner NEJM 2006) and that altered fractionation RT improves outcome compared to standard RT that is of similar magnitude as CRT (Bourhis Lancet 2006), led to the hypothesis that the combination of the two treatment strategies will improve efficacy compared to standard CRT with good tolerability. Methods: HN.6 is a Canadian phase III randomized study comparing standard RT 70Gy/35 over 7 weeks + cisplatin 100mg/m2 d 1, 22, 43 to accelerated RT 70Gy/35 over 6 weeks + panitumumab (anti EGFR Ab)) 9mg/kg 1 week prior to RT, d15, 36. Key eligibility criteria are: SCC of oral cavity, oropharynx, larynx or hypopharynx; TanyN+M0 or T3-4N0M0; adequate organ function and PS. Primary endpoint is progression free survival (PFS). Secondary endpoints include OS, local PFS, regional PFS, distant metastases, swallowing related QOL, functional swallowing outcomes, and economic evaluation (healthcare utilization, health utilities, indirect costs). Tissue and blood collection will allow biomarker evaluation including HPV status. Real time quality review of RT plans with plan data and radiology archiving will allow future analysis of RT parameters relative to toxicity and patterns of failure. Clinical epidemiological data will be prospectively collected and correlated with biomarkers and outcome. Planned sample size is 320 patients over 3.2 years with 3 more years of follow-up and target hazard ratio = 0.7 (absolute difference in control arm 2 year PFS of 12%, power 80%, 2-tail type 1 error 0.05). If superiority is not demonstrated, noninferiority will be tested. One interim analysis is planned. Conduct to Date: Study activation: Dec 2008 and completed accrual in Nov 2011. In Oct 2011, the DSMC recommended trial continuation. Supported by CCSRI grant 021039 and Amgen Inc. ClinicalTrials.gov: NCT00820248.

e14021 Background: KRAS mutation status is a predictive biomarker for resistance to EGFR antibodies among mCRC pts, and is recommended for use by ASCO and the FDA. Little is known about the uptake of clinical recommendations in oncology practice. We sought to study the effect of ASCO and FDA guidelines on the use of EGFR antibodies among a commercially insured population. Methods: The LifeLink Health Plan Claims Database (formerly the PharMetrics Patient-Centric Database) was used to create a cohort of >18 yo mCRC pts treated between 2004-2010. We identified treatment and diagnosis using ICD-9 or HCPCS (J) codes. We defined 1st line therapy as any chemotherapy +/- bevacizumab given after the pt had a claim for mCRC, excluding pts treated with EGFR antibodies in the 1st line. 2nd line therapy was defined as the initiation of a new chemotherapy agent (irinotecan/oxaliplatin) +/- EGFR antibody. We examined pts in two-month time intervals and calculated the fraction of pts in each interval who received EGFR antibody at any point beyond their 1st line treatment. Chi2 tests were used to compare treatment rates at the time points shown in the Table. Results: 5099 pts received 2nd line therapy of which 2603 pts received an EGFR antibody. Median age was 61 years, with 57% males. 59% received an EGFR antibody as a single agent. The remainder received this in combination with one or more of the following agents: fluorouracil 13.5%, irinotecan 36.7%, oxaliplatin 3.9%, and bevacizumab 6.1%. Rates of EGFR antibody use are outlined in the Table. Conclusions: The utilization of EGFR antibodies for mCRC treatment decreased following the presentation of clinical trial data, publication of ASCO guidelines and FDA label change. These data suggest that oncologists respond rapidly to new evidence and professional guidelines, and readily accept the use of predictive biomarkers in clinical practice. [Table: see text]

2567 Background: MEHD is a novel dual-action human IgG1 antibody that blocks ligand binding to HER3 and EGFR, and elicits antibody-dependent cell-mediated cytotoxicity (ADCC). MEHD demonstrates single-agent activity in a broad panel of tumor models, including models resistant to anti-HER3 or anti-EGFR treatment alone. The objective of this analysis was to characterize the PK of MEHD associated with body weight (BW)-based dosing used in a phase I study in patients with epithelial tumors and to evaluate the potential for using fixed dosing in future studies. Methods: Preliminary non-compartmental and population PK analyses were performed using patient data from the dose-escalation stage [1, 4, 10, 15, 22, and 30 mg/kg every two weeks (q2w)] and expansion stage (14 mg/kg q2w) of the phase I study. Patient demographic data and other relevant clinical covariates were evaluated in the population analysis. PK simulation of 1000 subjects with a log-normal BW distribution was performed to compare the inter-individual variability of MEHD exposure following fixed or BW-based dosing. Results: As expected,MEHD exhibited nonlinear PK. In the noncompartmenal analysis, the apparent clearance (CL) decreased in a dose-dependent fashion (about 40 to 9.9 mL/day/kg from 1 to 30 mg/kg) and approached linearity at doses >10 mg/kg (q2w). In the population analysis, the PK profile of MEHD was well described by a two compartment model with linear and nonlinear clearance. The target-mediated clearance was consistent with that of anti-EGFR antibodies. The nonspecific CL and central volume of distribution (V1) values were approximately 6 mL/day/kg and 52.4 mL/kg, respectively. BW had a moderate effect on V1, but not on CL. PK simulations suggest that, compared with BW-based dosing, fixed dosing would result in less inter-individual variability in MEHD exposure. Both 1100 mg q2w or 1650 mg q3w of MEHD achieve the targeted therapeutic exposure. Conclusions: The dual-action antibody MEHD demonstrated PK consistent with anti-EGFR antibodies. Fixed dosing of MEHD on an every 2 or 3 week schedule is supported.

e16008 Background: To explore the efficacy of the combination of biological target therapy and chemotherapy. Methods: Seventy-one patients (54 men and 17 women aged from 30 to 83 years; mean 60) wi...

e13022 Background: Targeting the epidermal growth factor receptor (EGFR) with monoclonal antibodies has proven to be an effective therapy for the treatment of cancer. In addition to blocking activation, antibodies directed to the ligand-binding domain also induce EGFR degradation. A number of EGFR antibodies are approved for use in patients and/or in clinical development, including cetuximab (chimeric IgG1), necitumumab (human IgG1), and panitumumab (human IgG2). It is important to understand the similarities and differences between these antibodies to guide future drug development strategies. Methods: We used confocal live cell microscopy to measure EGFR antibody internalization and EGFR degradation. To obtain kinetic data on antibody induced receptor degradation, a HELA reporter cell line expressing EGFR fused to the green fluorescent protein (GFP) was utilized to quantify the decrease in sum pixel intensity of EGFR-GFP over a 24-hour time course in live cells. EGFR antibody trafficking to the lysosome ...

3089 Background: Sym004 is a recombinant antibody 1:1 mixture of two chimeric anti-EGFR mAbs, which elicits superior cancer cell growth inhibition in preclinical models. Uniquely, Sym004 mediates cell surface receptor removal by triggering EGFR internalization and degradation. Results from a first-in-human multicenter trial evaluating safety and tolerability of multiple doses of Sym004 are reported. Methods: The trial comprises a dose-escalating part A (0.4 mg/kg-12 mg/kg) with classical 3+3 design after the first 2 cohorts and an extension part B at maximum tolerated dose (MTD). Patients (pts) received weekly IV infusions of Sym004 until disease progression or unacceptable toxicity. Pharmacokinetics and safety is evaluated weekly, with dose-limiting toxicities (DLT) assessed in the first 4 weeks, and tumor response every 8 weeks. Results: In part A, 17 pts (median age 60 years) were treated with doses up to 9 mg/kg without reaching the MTD: 0.4 mg/kg (1 had 6 doses), 0.75 mg/kg (1 had 35* doses), 1.5 mg/...

575 Background: Targeted therapies for MCRC have increased treatment (Tx) options in multiple therapy lines. Symptoms associated with MCRC Tx have not been well studied from the Pt perspective. Objective: To characterize symptoms reported by MCRC Pts treated with chemotherapy and/or targeted drugs at a large US oncology network. Methods: Pt reported symptom data were linked to electronic medical records and Pt charts from Georgia Cancer Specialists in Southeast US. MCRC Pts aged ≥18 years with ≥1 administration of chemo or targeted therapy between 1/2007-3/2009 were included. Pt reports captured 13 symptoms, onset, and severity. Due to small sample sizes, no statistical comparisons were conducted. Results: 332 MCRC Pts were included (median age 62 years, 47% male, median weight 74 kg, 48% ECOG PS 0 or 1). Amongst Pts receiving 1L Tx (n=299), 78% received bevacizumab (BV) +/- chemo, 4% cetuximab (CX) +/- chemo, 15% chemo only, and 2% other. 162 Pts received 2L Tx: 49% BV +/- chemo, 17% chemo only, 28% CX +/- chemo, and 6% other. The 5 most common symptoms in 1L Tx for all severity ratings were 36% fatigue, 20% nausea, 17% weight (wt) loss, 15% diarrhea, and 9% constipation. The 5 most common symptoms in all 2L Tx groups were 44% fatigue, 27% nausea, 19% diarrhea, 16% wt loss, and 11% abdomen pain. 2L moderate, severe, or disabling symptoms reported in >10% Pts receiving BV +/- chemo, CX +/- chemo, and chemo only Tx are shown in the table. Conclusions: The most commonly reported symptoms by 1L and 2L MCRC Pts were fatigue, nausea, diarrhea, and weight loss. Overall, a numerically higher % of 2L Pts treated with CX +/- chemo reported moderate, severe, and disabling symptoms than Pts receiving BV +/- chemo and chemo alone. Rash was not observed in the BV +/- chemo group. Further research of MCRC Pt reported symptoms in a larger sample size are warranted. [Table: see text] [Table: see text]

LBA5506 Background: Zalutumumab is a novel, fully human IgG1 mAb targeting the EGFr that has shown encouraging activity in SCCHN. Methods: Patients with noncurable SCCHN with an ECOG PS of 0-2 and centrally documented radiographic progressive disease (PD) within 6 months after platinum-therapy were randomized between zalutumumab monotherapy and best supportive care (BSC) in a 2:1 ratio. Stratification parameter was ECOG PS. Methotrexate (MTX) was allowed in the BSC arm only. Individual dose-titration of zalutumumab was applied (max. exposure 16 mg/kg). The primary endpoint was overall survival (OS), with progression free survival (PFS) as the only secondary endpoint to be compared between groups, using log-rank test. 231 deaths were required to statistically differentiate OS between groups with 80% power. Results: 286 patients (34F, 252M) were randomized. The median age was 57 years (range 18-78), 65% had distant metastasis and 17% were ECOG PS 2, all similar between groups. 78% of patients in BSC arm received MTX. Although a median OS of 6.7 months was observed in the zalutumumab group compared to 5.2 in the BSC group, this was not statistically significant (p=0.065). A clear improvement in PFS (P=0.001) was demonstrated. Zalutumumab showed a safety profile as expected within this drug class. Conclusions: This is the first controlled study to demonstrate that an EGFr-targeted antibody given as monotherapy induces a clinically meaningful improvement in PFS in patients with SSCHN who have failed platinum-based chemotherapy. [Table: see text] [Table: see text]

e13102 Background: Zalutumumab (HuMax-EGFr, clone-2F8), a fully human IgG1 EGFR antibody, currently in phase III clinical trials, was previously demonstrated to have a dual mechanism of action. Fir...

e22088 Background: Specific EGFR inhibition therapies are currently promising and advanced in the clinical setting. It is revealed patients with a colorectal cancer bearing mutated K-ras do not benefit from cetuximab, a chimeric mouse-human antibody to EGFR. However, appropriate evaluation of the therapeutic effects has not been clarified yet, because of the lack of reliable tumor response predictors. Measurement of tumor proliferative activity by PET using FLT may serve to assess early response of the therapy. The purpose of this study is to determine whether 18F- FLT is useful to evaluate very early response to cetuximab treatment in human lung cancer cell line xenograft. Methods: Human tumor xenograft model was established in male BALB/c athymic mice by human lung cancer cell line NCI-H1975, which expresses L858R/T790M-EGFR. These mice were assigned to two groups (n=5, each group): control and cetuximab-treated groups. Cetuximab was intra-peritoneally given 1.0mg/body once on the first day. Biodistribution of 3H-FLT (%Inject Dose/g/kg) were studied two days after the treatment. Immunohistochemical staining of EGFR, phosphorylated EGFR (pEGFR), and nuclear antigen Ki-67 as a tumor cell proliferation marker in tumor tissues were also studied to assess early effects of cetuximab. Results: FLT uptake was high in tumors compared with any other organs. Two days after the cetuximab therapy, the mean value of FLT uptake in tumor was significantly decreased to 55% of control value (0.38 ± 0.03 in control group vs. 0.21 ± 0.07 in cetuximab-treated group; p < 0.05). There were no statistical differences in the tumor volume and body weight of mice between each group. High expression of EGFR and Ki-67 were observed in this xenograft. As compared with control, Ki-67 expression was remarkably decreased in cetuximab-treated group, while there were no definite changes in expression of EGFR and pEGFR. Conclusions: In this animal model, FLT uptake and Ki-67 expression were decreased in cetuximab- treated group just two days after the treatment start. These results indicate FLT-PET can be a useful predictor to evaluate very early response to molecular targeted medicine such as cetuximab before significant change of tumor size. No significant financial relationships to disclose.

6077 Background: Recurrence of resected HNSCC is due to outgrowth of unrecognized residual cells, and/or to second field tumors. Epidermal growth factor receptor (EGFR) is overexpressed in HNSCC and in the mucosa surrounding the tumor. Evidence indicates that processes triggered by surgery stimulate recurrence of EGFR family overexpressing tumors. Methods: Tumors collected from 33 resected HNSCC patients were characterized for EGFR expression-activation using EGFR-DAKO Kit, EGFR antibody (528:sc- 120, Santa Cruz) and anti-phosphotyrosine antibody (clone 4G10, Upstate) for immunohistochemistry, immunoprecipitation/Western blott. EGFR FISH was performed on 2 tumors and surrounding dysplastic areas using the LSI EGFR/CEP 7 probe. WDFs at 24–48 hours after surgery of the 33 HNSCC patients and as control, from 23 plastic/reconstructive interventions were collected. WDFs were employed for stimulating the proliferation of two EGFR overexpressing squamous carcinoma cell lines (SCCLs) in which FISH detected gene a...

4546 Background: Combining the EGFR antibody cetuximab with chemotherapy has shown increased efficacy compared with chemotherapy alone in various types of cancer. This trial was conducted to assess...

12504 Background: Nimotuzumab (OSAG101, Theraloc) is a humanized monoclonal antibody (mAb) that binds to the EGFR. In preclinical studies the antibody has shown potent antitumor activity. Based on phase I data, the recommended dose has been established at 200 mg weekly. A previous phase II study in children with high grade brain tumors showed activity of nimotuzumab as a monotherapeutic agent, even in prognostically very unfavorable pontine glioma. No drug related side effects were reported. The present ongoing phase II study was aimed at evaluating the safety and efficacy of nimotuzumab monotherapy in patients (pts) with locally advanced or metastatic PC. Methods: Pts who failed standard chemotherapy with gemcitabine or another first line regimen for advanced disease and had at least one measurable lesion were eligible for the study. Nimotuzumab was given iv as induction therapy at 200 mg once weekly for 6 weeks. Follow up by CT was performed after 8 weeks. Pts continued receiving treatment 3-weekly until disease progression or unacceptable toxicity occurred. Endpoints included tumor response (RECIST), time to disease progression, and safety. Blood samples were collected prior to first dose, at end of infusion, and 3h, 6h, 48h, as well as every time before subsequent nimotuzumab doses were administered. Nimotuzumab concentrations in serum were measured by cellular ELISA. Results: Enrollment is complete, with treatment ongoing. In total, 55 pts were treated (28 women/ 27 men; ECOG status of 1 [n= 41] or 0 [n=14], median age 63.6 yrs [range 46–83 yrs]). Pts evaluable for response: n= 36; CR:0; PR:0; SD:6 pts (median TTP 19.2 weeks; 14.1–26.1). The only reported treatment-related adverse event was rash grade 1 in 1 pt. After 200 mg single dose, the mean value of Cmax was calculated to 141 ± 33 μg/ml. The t1/2 was calculated to 45 h, volume of distribution to 1.46 ± 0.3 l, respectively. The total clearance was determined to 23 ± 6 ml/h. The trough values after 168 h were 6.2 ± 6.3 μg/ml. Conclusions: These data confirm that nimotuzumab is safe and well tolerated. To improve efficacy, a combination trial with gemcitabine is planned. [Table: see text]

4028 Background: ECF (epirubicin, cisplatin and 5FU) is widely used for the treatment of advanced OG cancer. ECX, where capecitabine is substituted for 5FU has demonstrated comparable toxicity and ...

3077 Background: Matuzumab is a humanized monoclonal antibody binding to the EGFR with higher affinity than natural ligands (eg. TGF alpha,EGF) leading to inhibition of signal transduction pathways...

3156 Background: EG cancer is diagnosed in more than 60% of patients (pts) in a locally advanced or metastatic stage. In this situation treatment options are limited; therefore exploration of a new therapeutic regimen is warranted. EGFR is expressed in a high proportion of gastric cancers associated with poor prognosis. Matuzumab, a humanized monoclonal anti-EGFR IgG1 antibody, inhibits ligand-mediated receptor signalling and has demonstrated antitumor activity in solid tumors. In a phase I study we evaluated the safety, tolerability, and pharmacokinetics of matuzumab in combination with standard chemotherapy in pts with advanced EG adenocarcinoma. Methods: Weekly doses of matuzumab (400 mg or 800 mg) were administered in addition to PFL (cisplatin [50 mg/m2] days 1, 15, 29, and leucovorin [500 mg/m2] and 5-fluorouracil [2000 mg/m2] days 1, 8, 15, 22, 29, 36) on a 7-week cycle up to a maximum of 3 cycles. Tumor response was assessed by endoscopy and CT/MRI in the last week of each cycle. Blood samples wer...

3209 Background: Cetuximab is a monoclonal antibody that selectively binds to the Epidermal Growth Factor Receptor (EGFR). Cetuximab as a single agent is effective in patients with colorectal cance...

3157 Background: Receptor-tyrosine kinase (RTK) internalization is a key event in signaling and a requisite event for certain RTK-targeted therapeutics. Endocytosis is the hallmark of trastuzumab and immunoliposomes (ILs) efficacy. To provide a biomarker of ErbB internalization, we developed a quantitative assay of HER2 and EGFR endocytosis triggered by specific probes. Methods: scFv against HER2 (F5) or EGFR (C10) were linked to nickel-containing and fluorescence-labeled liposomes to generate ErbB-targeted immunoliposome probes (ILs-fluor). After incubation with ILs-fluor (2h, 37C), tumor cells were washed +/-EDTA to dissociate scFv from liposomes; this allows FACS-based quantitation of internalized ILs-fluor (EDTA-insensitive fraction) vs. cell-surface bound scFv (EDTA-sensitive). Results: Assay was validated against a panel of cell lines, and was highly specific (HER2- or EGFR-specific vs. irrelevant MAb) and sensitive (internalization measurable at very low HER2/EGFR content). In trastuzumab-sensitive...

3043 Background: EGFR is a potential therapeutic target in HNSCC. EGFR signaling inhibitors such as EMD 72000, a humanized anti-EGFR monoclonal antibody, have shown the potential for antitumor activity in subjects with EGFR-expressing cancers. However, it is undetermined whether EGFR saturation is a prerequisite for effective treatment. Methods: Accumulation of EMD 72000 in tumors of subjects with histologically confirmed HNSCC was measured, and saturation of EGFR by a single 200-mg dose was assessed. EMD 72000 was radiolabeled with I-123 and 2 mg were administered either simultaneously with (Group A; n = 9) or 24 h after (Group B; n = 5) infusion of 198 mg unlabelled antibody. Single photon emission computerized tomography (SPECT) of the neck, and planar whole body (WB) images were acquired 0.2, 4, 24, and 48 h after injection of radiolabeled EMD 72000. Serum was collected prior to infusion of the unlabelled dose and up to72 h thereafter for determination of pharmacokinetic (PK) parameters of the total a...