Baclofen and Tizanidine Adverse Effects Observed Among Community-Dwelling Adults Above the Age of 50 Years: A Systematic Review.

OBJECTIVE: This review highlights adverse effects of baclofen and tizanidine in older community-dwelling adults. DATA SOURCES: A literature search was conducted, including search terms of "adverse effect," "baclofen," "elderly," "falls," "fractures," and "tizanidine." Studies were included if they described community-dwelling adults aged 50 years and older who received oral baclofen or tizanidine. The Federal Drug Administration Adverse Event Reporting System (FAERS) data were compiled for adverse effect incidence. STUDY SELECTION AND DATA EXTRACTION: The literature search was completed in July 2019 and updated in June 2023. Reviews performed by 2 independent reviewers yielded 15 records. FAERS identified 486 (baclofen) and 305 (tizanidine) adverse effects of interest. DATA SYNTHESIS: Two retrospective cohort studies evaluating baclofen use in older adults showed increased hospitalizations for encephalopathy in chronic kidney disease (7.2% vs 0.1%) and end-stage renal disease (daily dose 20 mg or more; relative risk [RR] 19.8, 95% CI = [14.0-28.0]). Other articles were case reports; 10 articles reported dyskinesias, encephalopathy or disorientation, and drowsiness associated with baclofen, and 5 articles reported bradycardia and/or hypotension with tizanidine. The FAERS Public Dashboard revealed 12.1% and 28.7% overall incidence of adverse effects of interest, with a 27.8% and 29.2% incidence of falls for baclofen and tizanidine, respectively. Baclofen and tizanidine are associated with concerning adverse effects in older adults. Alternative agents should be considered, but, if necessary, providers should start at lower doses and increase slowly. CONCLUSIONS: This review highlights the importance of using baclofen and tizanidine with caution in older adults.

Health Behavior Changes Among Adults in the Supplemental Nutrition Assistance Program Education, Los Angeles County, California.

PURPOSE AND OBJECTIVES: The Supplemental Nutrition Assistance Program Education (SNAP-Ed), the educational branch of SNAP, can play an important role in improving dietary outcomes, eliminating food insecurity, and preventing chronic disease among low-income populations. This study examined the effects of local SNAP-Ed efforts on self-reported health behaviors and body mass index (BMI) over a 1-year period, using data collected from intercept surveys of program-eligible adults. INTERVENTION APPROACH: From 2016 to 2020, the Los Angeles County Department of Public Health partnered with 24 community-based organizations to provide nutrition education and to implement policy, systems, and environmental changes in the community. EVALUATION METHODS: A cross-sectional survey was conducted in 2018 and repeated in 2019 to measure 6 outcomes describing population-level changes in health behaviors and BMI. The study recruited 4 samples: 2 samples from outside selected supermarkets (2018, n = 2,098; 2019, n = 2,323) and 2 samples from participants at SNAP-Ed class sites (2018, n = 651; 2019, n = 569). RESULTS: While study results showed an increase in consumption of fruits and vegetables and in vigorous physical activity, they also showed an increase in BMI and high consumption of unhealthy foods. Participating in SNAP-Ed classes was positively associated with several health behaviors but no change in BMI. Participants who experienced food insecurity had worse health behavior outcomes than those who did not experience this condition. IMPLICATIONS FOR PUBLIC HEALTH: SNAP-Ed interventions appear to have a favorable effect on fruit and vegetable consumption, but increases in BMI suggest that unhealthy food consumption is abundant and may be counteracting the benefits gained from eating more fruits and vegetables. Future efforts should take these results into consideration and optimize enrollment in nutrition assistance programs. These efforts should include coordinating with local programs to increase healthy food access for at-risk low-income populations in Los Angeles County.

Food insecurity, participating in the Supplemental Nutrition Assistance Program, and the degree to which patients anticipate help from clinics to find food in Los Angeles County.

Healthcare clinics are uniquely positioned to screen for food insecurity and refer patients to food resources. This study examines this approach to address this social condition. A 2018 intercept survey of 1,103 adult patients recruited from across 11 clinic waiting rooms in Los Angeles County was conducted to describe the prevalence of food insecurity and whether Supplemental Nutrition Assistance Program (SNAP) participation and the degree to which patients anticipated their clinics to help them locate food varied by socio-demographic factors. The prevalence of food insecurity was high for this low-income survey sample (63.4%); 72% of Spanish-speaking Latinx reported experiencing it. For those who experienced food insecurity, older age was associated with lower odds of SNAP participation. Spanish-speaking Latinx had higher odds of anticipating help from a clinic to find food relative to English-speaking Latinx (Adjusted Odds Ratio 1.88, 95% Confidence Interval: 1.18, 2.98). An exploratory analysis showed that common reasons for not enrolling in SNAP included older adults not knowing how to apply to the program and Spanish-speaking Latinx worrying about citizenship status as it relates to the eligibility process. Findings revealed disparities in the prevalence of food insecurity and SNAP participation among patients of Los Angeles' low income clinics. Information from this study can help inform low-income clinics' efforts to intervene on food insecurity in their patient population.

Use of Population Health Data and Qualitative Analysis to Guide Local Planning and Implementation of Supplemental Nutrition Assistance Program Education.

PURPOSE: The purpose is to describe how local quantitative and qualitative data were used to assess the progress of the Supplemental Nutrition Assistance Program Education (SNAP-Ed) interventions in Los Angeles County, California. APPROACH: Data from the California Health Interview Survey informed the geographical concentration of program resources during the planning phase. At the end of the program, semi-structured interviews with stakeholders were conducted to assess factors that facilitated SNAP-Ed implementation. SETTING: Los Angeles County, California. PARTICIPANTS: Twenty-four project coordinators were interviewed. INTERVENTION: From 2016 to 2020, 24 organizations across Los Angeles County delivered nutrition education, reaching an estimated 2 million people. Two-hundred policy, systems, and environmental change interventions reached an estimated 1.2 million people. METHOD: Semi-structured interview data were analyzed using a form of both inductive and deductive content analysis. A codebook was developed based on themes identified in these interviews. Each interview was coded by 2 team members; discrepancies (if they arose) were resolved by a 5-member group. RESULTS: Two facilitators-support for capacity building from a local health department and presence of community partnerships-were identified as critical factors that contributed to the success of SNAP-Ed implementation. CONCLUSION: A local health department can increase SNAP-Ed intervention reach and uptake by assisting funded partners with further capacity building, helping them to develop feasible work plans, foster evaluation skills, and engage in sustainability planning.

Anti-epidermal growth factor receptor monoclonal antibody cetuximab inhibits EGFR/HER-2 heterodimerization and activation.

Human carcinomas frequently express one or more members of the epidermal growth factor receptor family. Two family members, epidermal growth factor receptor (EGFR) and c-erbB2/neu (HER2), homodimerize or heterodimerize upon activation with ligand and trigger potent mechanisms of cellular proliferation, differentiation and migration. In this study, we examined the effect of the anti-EGFR monoclonal antibody Erbitux (cetuximab) on human tumor cells expressing both EGFR and HER2. Investigation of the effect of cetuximab on the activation of EGFR-EGFR, EGFR-HER2 and HER2-HER2 homodimers and heterodimers was conducted using the NCI-N87 human gastric carcinoma cell line. Treatment of NCI-N87 cells with cetuximab completely inhibited formation of EGFR-EGFR homodimers and EGFR-HER2 heterodimers. Activation of HER2-HER2 homodimers was not appreciably stimulated by exogenous ligand and was not inhibited by cetuximab treatment. Furthermore, cetuximab inhibited EGF-induced EGFR and HER2 phosphorylation in CAL27, NCI-H226 and NCI-N87 cells. The activation of downstream signaling molecules such as AKT, MAPK and STAT-3 were also inhibited by cetuximab in these cells. To examine the effect of cetuximab on the growth of tumors in vivo, athymic mice bearing established NCI-N87 or CAL27 xenografts were treated with cetuximab (1 mg, i.p., q3d). The growth of NCI-N87 and CAL27 tumors was significantly inhibited with cetuximab therapy compared to the control groups (p<0.0001 in both cases). In the CAL27 xenograft model, tumor growth inhibition by cetuximab treatment was similar to that by cetuximab and trastuzumab combination treatment. Immunohistological analysis of cetuximab-treated tumors showed a decrease in EGFR-HER2 signaling and reduced tumor cell proliferation. These results suggest that cetuximab may be useful in the treatment of carcinomas co-expressing EGFR and HER2.

Calcium/Phosphate Solubility Curves for Premasol and Trophamine Pediatric Parenteral Nutrition Formulations.

OBJECTIVES: Calcium and phosphate incompatibility in parenteral nutrition formulations remains a critical concern for patient safety. This study examined calcium phosphate solubility for 2-in-1 admixtures prepared using 2 commercially available pediatric amino acid solutions (Premasol, Baxter Healthcare Corp; or Trophamine, B. Braun Medical Inc), applying identical test methods, storage conditions, and acceptance criteria. METHODS: Parenteral 2-in-1 admixtures included amino acid; dextrose; static concentrations of sodium, potassium, and magnesium, and varying concentrations of calcium (0-60 mEq/L), phosphate (15-50 mmol/L), and cysteine. Three replicate samples were stored for 48 hours at 40°C ± 2°C and then visually inspected for particulate matter, evaluated for subvisible particulate matter, when particulate matter was noted, microscopic examination was performed to confirm the presence of calcium phosphate crystals. Pass criteria were: all replicates free of visible particulate matter related to calcium phosphate crystals and particle counts below US Pharmacopeia <788> limits. RESULTS: Premasol and Trophamine generated identical calcium phosphate curves for 2% amino acid formulations containing 20% dextrose with/without cysteine, and similar curves for the 1% or 3% amino acid formulations containing 10% or 20% dextrose with/without cysteine. Calcium phosphate particles were identified in failed samples by scanning electron microscopy/energy dispersive X-ray spectroscopy. Calcium phosphate solubility was higher in formulations containing cysteine 40 mg/g amino acid vs. cysteine 20 mg/g amino acid and in cysteine 20 mg/g amino acid vs. no cysteine. CONCLUSIONS: Admixtures made with 1%, 2%, or 3% Premasol or Trophamine have essentially equivalent calcium phosphate solubility curves when tested with identical methods, storage conditions, and acceptance criteria.

Enhanced suppression of melanoma tumor growth and metastasis by combined therapy with anti-VEGF receptor and anti-TYRP-1/gp75 monoclonal antibodies.

Targeted immunotherapy against tumors or angiogenesis has shown promise as an alternative approach for the treatment of malignant disease. Whether or not combining these two treatment modalities would enhance the antitumor effect was tested in mouse models of malignant melanoma. C57BL/6 mice bearing established subcutaneous B16 tumors were treated with anti-vascular endothelial growth factor receptor (anti-VEGFR) fetal liver kinase-1 (Flk-1) monoclonal antibody (mAb) DC101 and/or anti-TYRP-1/gp75 (tyrosinase-related protein-1) mAb TA99. The growth of subcutaneous B16 tumors was significantly suppressed by the mAb DC101 (63%, p<0.001) and by mAb TA99 (75%, p<0.001) treatment alone. The combined antibody (TA99+DC101) treatment resulted in a significant enhancement (93%, p<0.001) of tumor growth suppression. In a B16 pulmonary metastasis model, combined therapy with mAb DC101 and mAb TA99 resulted in a significant reduction of lung metastases compared to the control (p<0.001) and the single agent treatment groups (p<0.05). A combined modality approach that provides passive immunity to melanoma differentiation antigens as well as inhibiting tumor neovascularization may be valuable for the treatment of malignant melanoma.

Discovery and characterization of novel, potent, non-peptide parathyroid hormone-1 receptor antagonists.

A 1,3,4-benzotriazepine was identified as a suitable lead in our effort toward obtaining a non-peptide parathyroid hormone-1 receptor (PTH1R) antagonist. A process of optimization afforded derivatives displaying nanomolar PTH1R affinity, a representative example of which behaved as a PTH1R antagonist in cell-based cyclic adenosine monophosphate (cAMP) assays, with selectivity over PTH2 receptors.

Monoclonal antibody cetuximab binds to and down-regulates constitutively activated epidermal growth factor receptor vIII on the cell surface.

BACKGROUND: The epidermal growth factor receptor (EGFR) plays an important role in the growth and survival of many human tumors of epithelial origin. EGFR variant III (EGFRvIII) is a truncated form of EGFR that does not bind ligand, is constitutively active, and is reported to be coexpressed with EGFR in some human tumors including breast, glioblastoma, lung, and prostate. MATERIALS AND METHODS: Here we have tested the anti-EGFR monoclonal antibody cetuximab for its interaction with EGFRvIII. Chinese hamster ovary (CHO), 32D (non-tumorigenic murine hematopoetic cells), and U87-MG stable transfectants were generated to express EGFRvIII. RESULTS: Analysis of receptor phosphorylation showed that the EGFRvIII was constitutively phosphorylated in transfected cells. Flow cytometry, direct binding, and immunoprecipitation analysis of EGFRvIII transfectants showed specific binding of cetuximab to EGFRvIII. Cetuximab bound to EGFRvIII with a KD of 0.38 nM determined by Scatchard analysis and 1.1 nM determined by Biacore analysis respectively. In internalization studies, binding of cetuximab to the EGFRvIII on the cell surface led to at least 50% of the cetuximab-EGFRvIII complex internalized from cell surface of CHO-EGFRvIII after 3 hours. This internalization led to a reduction in phosphorylated EGFRvIII in transfected cells. Furthermore, incubation of cells expressing EGFRvIII with cetuximab resulted in 40-50% inhibition of cell proliferation. CONCLUSION: These data suggest that cetuximab may be a potential candidate for the treatment of tumors that also express EGFRvIII.

Generation and characterization of a therapeutic human antibody to melanoma antigen TYRP1.

TYRP1 (tyrosinase-related protein 1) is a melanoma antigen expressed in melanosomes and on the surface of melanoma cells. Previous studies have shown that mouse antibodies to TYRP1 localized to melanomas in vivo and inhibited tumor growth and metastasis. Here, we describe the characterization of a novel fully human anti-TYRP1 MAb (20D7) generated by immunizing HuMAb mice (Medarex). 20D7 recognized recombinant and native human TYRP1 by Western blotting and ELISA, and native TYRP1 in melanoma cells as determined by flow cytometry analysis. 20D7 cross-reacted with mouse TYRP1. The binding affinity to human TYRP1 for the human MAb was in the low nM range as determined by surface plasmon resonance kinetics. 20D7 can bind to human and mouse Fc receptor and induce a strong ADCC response against human melanoma cells in vitro. The antitumor activity of 20D7 was tested in human melanoma xenografts and mouse metastatic melanoma models in athymic nude mice. Growth of s.c. human melanoma tumors and metastatic nodules of murine B16 tumor were significantly suppressed by 20D7 compared to human IgG control. These results suggest that human anti-TYRP1 MAb may be a potent therapeutic for the treatment of malignant melanoma.

Action of celgosivir (6 O-butanoyl castanospermine) against the pestivirus BVDV: implications for the treatment of hepatitis C.

Alpha-glucosidase I inhibitors have been shown to inhibit the replication of a broad range of enveloped viruses by preventing the correct folding of their envelope glycoproteins. This study assesses the potential of 6 O-butanoyl castanospermine (celgosivir) as a treatment for hepatitis C virus (HCV). In the absence of an adequate culture system for HCV, the closely related virus, bovine viral diarrhoea virus (BVDV), was used as a surrogate model. Using both a plaque assay and a cytopathic effect assay, celgosivir (IC50 16 and 47 microM respectively) was shown to be more potent than N-nonyl DNJ (105 and 74 microM), castanospermine (110 and 367 microM) and N-butyl DNJ (> 250 and 550 microM). Of the alpha-glucosidase inhibitors tested, only N-nonyl DNJ showed evidence of toxicity (CC50 > or = 120 microM). Two-way combinations of interferon-alpha, ribavirin and either celgosivir or castanospermine demonstrated that each could enhance the antiviral efficacy of the others, either additively or synergistically. The observation that the number of viral genomes released from BVDV-infected cells was inhibited by either castanospermine or celgosivir in parallel with the number of infectious units was taken as confirmation that these alpha-glucosidase I inhibitors block the production or release of flavivirus particles.

Conservation of receptor antagonist anti-tumor activity by epidermal growth factor receptor antibody expressed in transgenic corn seed.

Recombinant protein production in plants such as corn is a promising means to generate high product yields at low comparable production cost. The anti-EGFR monoclonal antibody C225, cetuximab, is a well-characterized receptor antagonist antibody recently approved for the treatment of refractory colorectal cancer. We initiated a study to test and compare the functional activity of glycosylated and aglycosylated C225 produced in stable transgenic corn seed. Both corn antibodies were shown to be functionally indistinguishable from mammalian-derived C225 in demonstrating high-affinity binding to the EGF receptor, blocking of ligand-dependent signaling, and inhibiting cell proliferation. In addition, consistent with cetuximab, both corn antibodies possessed strong anti-tumor activity in vivo. Acute dose primate pharmacokinetic studies, however, revealed a marked increase in clearance for the glycosylated corn antibody, while the aglycosylated antibody possessed in vivo kinetics similar to cetuximab. This experimentation established that corn-derived receptor blocking monoclonal antibodies possess comparable efficacy to mammalian cell culture-derived antibody, and offer a cost effective alternative to large-scale mammalian cell culture production.

Automated system for kinetic analysis of particle size distributions for pharmaceutically relevant systems.

Detailing the kinetics of particle formation for pharmaceutically relevant solutions is challenging, especially when considering the combination of formulations, containers, and timescales of clinical importance. This paper describes a method for using commercial software Automate with a stream-selector valve capable of sampling container solutions from within an environmental chamber. The tool was built to monitor changes in particle size distributions via instrumental particle counters but can be adapted to other solution-based sensors. The tool and methodology were demonstrated to be highly effective for measuring dynamic changes in emulsion globule distributions as a function of storage and mixing conditions important for parenteral nutrition. Higher levels of agitation induced the fastest growth of large globules (≥5 µm) while the gentler conditions actually showed a decrease in the number of these large globules. The same methodology recorded calcium phosphate precipitation kinetics as a function of [Ca(2+)] and pH. This automated system is readily adaptable to a wide range of pharmaceutically relevant systems where the particle size is expected to vary with time. This instrumentation can dramatically reduce the time and resources needed to probe complex formulation issues while providing new insights for monitoring the kinetics as a function of key variables.

Probability-based compatibility curves for calcium and phosphates in parenteral nutrition formulations.

BACKGROUND: The information content of the calcium phosphate compatibility curves for adult parenteral nutrition (PN) solutions may benefit from a more sophisticated statistical treatment. Binary logistic regression analyses were evaluated as part of an alternate method for generating formulation compatibility curves. MATERIALS AND METHODS: A commercial PN solution was challenged with a systematic array of calcium and phosphate concentrations. These formulations were then characterized for particulates by visual inspection, light obscuration, and filtration followed by optical microscopy. Logistic regression analyses of the data were compared with traditional treatments for generating compatibility curves. RESULTS: Assay-dependent differences were observed in the compatibility curves and associated probability contours; the microscopic method of precipitate detection generated the most robust results. Calcium and phosphate compatibility data generated from small-volume glass containers reasonably predicted the observed compatibility of clinically relevant flexible containers. CONCLUSIONS: The published methods for creating calcium and phosphate compatibility curves via connecting the highest passing or lowest failing calcium concentrations should be augmented or replaced by probability contours of the entire experimental design to determine zones of formulation incompatibilities. We recommend researchers evaluate their data with logistic regression analysis to help build a more comprehensive probabilistic database of compatibility information.

Interactions between Parenteral Lipid Emulsions and Container Surfaces.

OBJECTIVE: To evaluate the relationship between changes in emulsion globule size distributions and container uptake of lipid emulsions in total nutrient admixtures. METHODS: A total nutrient admixture was prepared from a commercial lipid emulsion, 20% ClinOleic®, separated into glass (borosilicate) and ethylene vinyl acetate (EVA) plastic containers, and then stored at ambient conditions for approximately 24 h. The large globule size distribution was monitored continuously for both containers, and the quantity of triglycerides associated with both containers was measured by liquid chromatography. The changes in mass of the EVA containers were also measured gravimetrically. RESULTS: The volume percent of globules greater than 5 microns in diameter (PFAT5) levels for an emulsion admixture in EVA containers showed a 75% reduction compared to a marginal decrease of PFAT5 when in the glass container. Extraction of the containers showed that the quantity of triglycerides associated with the EVA surfaces steadily increased with emulsion exposure time, while the glass showed a significantly lower triglyceride content compared to the EVA. Gravimetric measurements confirmed that the EVA containers gained significant mass during exposure to the emulsion admixture. CONCLUSION: A time-dependent decrease in PFAT5 values for an emulsion admixture was associated with container triglyceride absorption where EVA containers had a greater uptake than glass containers. The larger globules appear to absorb preferentially, and the admixture globule size distribution fraction represented by PFAT5 accounts for 15-20% of the total triglyceride adsorption to the container. LAY ABSTRACT: The goal of this work is to evaluate how emulsions in total nutrition admixtures are affected by the containers within which they are stored. Specifically, the study examines how the emulsion globule size distribution in different containers is related to adsorption or absorption of the lipids onto or into the container. The admixtures were prepared from a commercial lipid emulsion, 20% ClinOleic®, and the containers were either glass (borosilicate) or plastic (ethylene vinyl acetate, EVA). The large globule size distribution was monitored continuously for both containers over the course of 24 h, and the quantity of triglycerides taken up by both containers was measured by liquid chromatography. The lipid uptake by the EVA containers was also monitored by gravimetric methods. Briefly, the percent of fat globules greater than 5 micrometers (PFAT5) in EVA containers showed a 75% reduction compared to a marginal decrease of PFAT5 when in the glass container. Extraction of the lipids from the containers showed that the quantity of triglycerides associated with the EVA surfaces steadily increased with admixture exposure time, while the glass showed a significantly lower triglyceride content. Gravimetric measurements confirmed that the EVA containers gained measurable mass during exposure to the emulsion admixture.

Removal of a C-terminal serine residue proximal to the inter-chain disulfide bond of a human IgG1 lambda light chain mediates enhanced antibody stability and antibody dependent cell-mediated cytotoxicity.

Optimization of biophysical properties is a critical success factor for the developability of monoclonal antibodies with potential therapeutic applications. The inter-domain disulfide bond between light chain (Lc) and heavy chain (Hc) in human IgG1 lends structural support for antibody scaffold stability, optimal antigen binding, and normal Fc function. Recently, human IgG1λ has been suggested to exhibit significantly greater susceptibility to reduction of the inter Lc-Hc disulfide bond relative to the same disulfide bond in human IgG1κ. To understand the molecular basis for this observed difference in stability, the sequence and structure of human IgG1λ and human IgG1κ were compared. Based on this Lc comparison, three single mutations were made in the λ Lc proximal to the cysteine residue, which forms a disulfide bond with the Hc. We determined that deletion of S214 (dS) improved resistance of the association between Lc and Hc to thermal stress. In addition, deletion of this terminal serine from the Lc of IgG1λ provided further benefit, including an increase in stability at elevated pH, increased yield from transient transfection, and improved in vitro antibody dependent cell-mediated cytotoxicity (ADCC). These observations support the conclusion that the presence of the terminal serine of the λ Lc creates a weaker inter-chain disulfide bond between the Lc and Hc, leading to slightly reduced stability and a potential compromise in IgG1λ function. Our data from a human IgG1λ provide a basis for further investigation of the effects of deleting terminal serine from λLc on the stability and function of other human IgG1λ antibodies.

IgG isotype, glycosylation, and EGFR expression determine the induction of antibody-dependent cellular cytotoxicity in vitro by cetuximab.

PURPOSE: To evaluate the antibody-dependent cellular cytotoxicity (ADCC) of cetuximab, an anti-epidermal growth factor receptor (EGFR) IgG1 antibody, in vitro. METHODS: Binding to human Fc receptors was measured by ELISA. ADCC against a panel of tumor cell lines was evaluated using peripheral blood mononuclear cells or NK cells as effectors and lactate dehydrogenase release as a marker of cell killing. Cetuximab was compared with two glycan variants of cetuximab and with panitumumab, an anti-EGFR IgG2. RESULTS: Cetuximab bound with high affinity to FcγRI (EC50 = 0.13 nM) and FcγRIIIa (EC50 = 6 nM) and effectively induced ADCC across multiple tumor cell lines. Panitumumab and aglycosylated cetuximab did not bind to FcγRI or FcγRIIIa nor have ADCC activity even at high effector-target cell ratios, even though the EGFR-binding affinity of cetuximab and panitumumab were shown to be comparable (KD = 87 pM and 83 pM, respectively). The extent of cetuximab-elicited ADCC was associated with the level of EGFR expression on tumor cells. CONCLUSIONS: Cetuximab elicits effective ADCC activity against a wide range of tumor cells in vitro. This activity is dependent on antibody glycosylation and IgG1 isotype as well as tumor-cell EGFR expression. These findings suggest that ADCC may contribute to the antitumor activity of cetuximab.

A fully human recombinant IgG-like bispecific antibody to both the epidermal growth factor receptor and the insulin-like growth factor receptor for enhanced antitumor activity.

Both the epidermal growth factor receptor (EGFR) and the insulin-like growth factor receptor (IGFR) have been implicated in the tumorigenesis of a variety of cancers. Here we propose that simultaneous targeting of both receptors with a bispecific antibody would lead to enhanced antitumor activity. To this end, we produced a recombinant human IgG-like bispecific antibody, a Di-diabody, using the variable regions from two antagonistic antibodies: IMC-11F8 to EGFR and IMC-A12 to IGFR. The Di-diabody binds to both EGFR and IGFR and effectively blocked both EGF- and IGF-stimulated receptor activation and tumor cell proliferation. The Di-diabody also inherited the biological properties from both of its parent antibodies; it triggers rapid and significant IGFR internalization and degradation and mediates effective antibody-dependent cellular cytotoxicity in a variety of tumor cells. Finally, the Di-diabody strongly inhibited the growth of two different human tumor xenografts in vivo. Our results underscore the benefits of simultaneous targeting of two tumor targets with bispecific antibodies.