EGFR and HER2 expression in cervical cancer patients in Ibadan, Nigeria

Cervical cancer is a leading cause of cancer-related deaths in developing countries, including Nigeria where it is the second most common female malignancy. Studies from elsewhere have demonstrated the relationship between epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) and advanced cervical cancer. However, we are not aware of such studies in Nigerian patients. The main objective of the study was to determine the prevalence of EGFR or HER1 and HER2 protein expression in cervical cancers and to determine their impact on overall survival. Clinical data and formalin-embedded tissue blocks of 124 patients who presented in the Radiation Oncology Department, University College Hospital (UCH), from 2006 to 2015 and had their histological diagnosis at the Pathology Department, UCH were retrieved and analysed for EGFR and HER2 expression using immunohistochemistry. EGFR expression was analysed using the immunoreactivity score by Remmele and Stegner. HER2 was analysed using the Hercep® test kit guidelines. Survival analysis was done using Kaplan-Meier and Cox regression analysis. Missing data were reported as missing, not documented. EGFR (immunoreactivity score > 4) was overexpressed in 26.6% of the 124 cervical tissue samples tested. Most patients whose samples were positive for EGFR were young, had squamous cell carcinoma and advanced diseases. HER2 was overexpressed in two samples (1.6%). The 5-year overall survival rate of the patients was 28.3%. The 5-year survival rate of patients who were EGFR positive was 9.5% and 34.1% for those who were EGFR negative. Screening for EGFR should be considered in cervical cancer patients. HER2 was overexpressed in two cervical tissue samples in this study and may be of poor interest as a potential target in the management of cervical cancer patients. Large prospective multi-institutional studies should be considered to further explore the relationship between EGFR and survival in cervical cancer patients.

Identifying the effectiveness of 3D culture systems to recapitulate breast tumor tissue in situ

PURPOSE

Breast cancer heterogeneity contributes to chemotherapy resistance and decreased patient survival. To improve patient outcomes it is essential to develop a technology that is able to rapidly select the most efficacious therapy that targets the diverse phenotypes present within the tumor. Breast cancer organoid technologies are proposed as an attractive approach for evaluating drug responses prior to patient therapy. However, there remain challenges in evaluating the effectiveness of organoid cultures to recapitulate the heterogeneity present in the patient tumor in situ.

METHOD

Organoids were generated from seven normal breast and nineteen breast cancer tissues diagnosed as estrogen receptor positive or triple negative. The Jensen-Shannon divergence index, a measure of the similarity between distributions, was used to compare and evaluate heterogeneity in starting tissue and their resultant organoids. Heterogeneity was analyzed using cytokeratin 8 and cytokeratin 14, which provided an easily scored readout.

RESULTS

In the in vitro culture system HER1 and FGFR were able to drive intra-tumor heterogeneity to generate divergent phenotypes that have different sensitivities to chemotherapies.

CONCLUSION

Our methodology, which focuses on quantifiable cellular phenotypes, provides a tractable system that complements omics approaches to provide an unprecedented view of heterogeneity and will enhance the identification of novel therapies and facilitate personalized medicine.

CAR-NK Cells Targeting HER1 (EGFR) Show Efficient Anti-Tumor Activity against Head and Neck Squamous Cell Carcinoma (HNSCC)

(1) Background: HNSCC is a highly heterogeneous and relapse-prone form of cancer. We aimed to expand the immunological tool kit against HNSCC by conducting a functional screen to generate chimeric antigen receptor (CAR)-NK-92 cells that target HER1/epidermal growth factor receptor (EGFR). (2) Methods: Selected CAR-NK-92 cell candidates were tested for enhanced reduction of target cells, CD107a expression and IFNγ secretion in different co-culture models. For representative HNSCC models, patient-derived primary HNSCC (pHNSCC) cell lines were generated by employing an EpCAM-sorting approach to eliminate the high percentage of non-malignant cells found. (3) Results: 2D and 3D spheroid co-culture experiments showed that anti-HER1 CAR-NK-92 cells effectively eliminated SCC cell lines and primary HNSCC (pHNSCC) cells. Co-culture of tumor models with anti-HER1 CAR-NK-92 cells led to enhanced degranulation and IFNγ secretion of NK-92 cells and apoptosis of target cells. Furthermore, remaining pHNSCC cells showed upregulated expression of putative cancer stem cell marker CD44v6. (4) Conclusions: These results highlight the promising potential of CAR-NK cell therapy in HNSCC and the likely necessity to target multiple tumor-associated antigens to reduce currently high relapse rates.

Expression of epidermal growth factor receptor and human epidermal growth factor receptor 2 in urothelial bladder carcinoma in an Egyptian cohort: Clinical implication and prognostic significance

BACKGROUND

Bladder cancer (BC) has a particular importance in Egyptian patients due to aggressive behavior and absence of prognostic markers.

OBJECTIVE

To evaluate the expression of gene and protein expression of HER2 and epidermal growth factor (EGFR) in Egyptian patients with BC and ultimately to investigate their clinical implication and prognostic significance.

MATERIAL AND METHODS

The study was carried out on 46 patients with urothelial bladder BC. Tissue were obtained from transurethral resection (N = 22) and radical cystectomy (N = 24) specimens. The original hematoxylin and eosin slides were re-evaluated and the formalin fixed, paraffin-embedded (FFPE) tissues which had sufficient tumor tissue (>75%) and minimal or absent tumor necrosis were selected for immunohistochemistry (IHC) and RNA extraction. Furthermore, five control biopsies were obtained from patients with cystitis. Follow-up data were retrieved from the medical records which included the treatment regimen, disease recurrence and/or progression, and survival.

RESULTS

EGFR and HER2 protein were overexpressed in 35% and 46% of patients respectively. EGFR was correlated with the tumor size, grade and pathological stage, with a similar trend for HER2. The recurrence rate was higher in patients with expression of any of the markers. Gene expression was significantly higher (10.6-folds) for EGFR and (21-folds) for HER2 in patients with BC in comparison to control patients. Survival analysis showed lower median disease-free survival in association with HER2 protein overexpression.

CONCLUSIONS

Our data highlighted the prognostic significance of EGFR and HER in BC and proposed their possible use as predictive markers and potential therapeutic targets.

First-in-human trial exploring safety, antitumor activity, and pharmacokinetics of Sym013, a recombinant pan-HER antibody mixture, in advanced epithelial malignancies

PURPOSE

 Sym013 contains six humanized monoclonal antibodies that bind to non-overlapping epitopes on three human epidermal growth factor receptors (HER1-3). Preclinical studies suggested Sym013 strongly suppresses growth of multiple epithelial tumors. This is a first-in-human study exploring safety and efficacy of Sym013 in patients with advanced epithelial malignancies.

METHODS

 Dose escalation used single-patient cohorts until the stopping rule was met, followed by 3 + 3 design. Dose levels planned were: 1, 2, 4, 6, 9, 12, 15, and 18 mg/kg. Treatment cycles were 28 days with imaging every eight weeks. Serum samples were collected at multiple time points for assessment of pharmacokinetics and development of anti-drug antibodies.

RESULTS

 Thirty-two patients were enrolled with multiple solid tumors, most common being colorectal cancer (CRC; 10/32, 31%). Due to mucositis, rash, and diarrhea at 4 mg/kg once-weekly, dosing was changed to biweekly (Q2W). Mandatory prophylaxis was added due to Grade 3 infusion-related reaction and oral mucositis at 9 mg/kg Q2W. The 15 mg/kg Q2W cohort was enrolling when the study was terminated for business reasons. Most common adverse events were skin (81%) and gastrointestinal (75%) disorders, including dermatitis/rash, stomatitis, and diarrhea. One patient with CRC achieved a partial response; 12 patients with varied malignancies had stable disease.

CONCLUSION

 During the conduct of the study, management of frequent infusion-related reactions, skin toxicities, and mucosal disorders, which are indicative of HER inhibition, necessitated multiple protocol amendments. The investigators, in concert with the Sponsor, agreed that achieving a tolerated regimen with acceptable target saturation was unlikely.

TRIAL REGISTRY

www.clinicaltrials.gov ; NCT02906670 (September 20, 2016).

Artificial Scaffold Polypeptides As an Efficient Tool for the Targeted Delivery of Nanostructures In Vitro and In Vivo

The use of traditional tools for the targeted delivery of nanostructures, such as antibodies, transferrin, lectins, or aptamers, often leads to an entire range of undesirable effects. The large size of antibodies often does not allow one to reach the required number of molecules on the surface of nanostructures during modification, and the constant domains of heavy chains, due to their effector functions, can induce phagocytosis. In the recent two decades, targeted polypeptide scaffold molecules of a non-immunoglobulin nature, antibody mimetics, have emerged as much more effective targeting tools. They are small in size (3–20 kDa), possess high affinity (from subnano- to femtomolar binding constants), low immunogenicity, and exceptional thermodynamic stability. These molecules can be effectively produced in bacterial cells, and, using genetic engineering manipulations, it is possible to create multispecific fusion proteins for the targeting of nanoparticles to cells with a given molecular portrait, which makes scaffold polypeptides an optimal tool for theranostics.

Nuclear HER3 expression improves the prognostic stratification of patients with HER1 positive advanced laryngeal squamous cell carcinoma

Background

Compared to the other members of human epidermal growth factor family receptors (HER), the role of HER3 has not been well defined in laryngeal cancer. The predictive and prognostic role of HER3 has been the focus of clinical attention but the research findings are contradictory, especially in laryngeal squamous cell carcinoma (LSCC). The variable localization of HER3 within cancer cells and the role of HER3 in primary and acquired resistance to HER1-targeted therapies remain unclear.

Methods

We performed a retrospective analysis of two cohorts of 66 homogeneous consecutive untreated primary advanced LSCC patients, in which co-expression of HER1, HER2 and HER3 receptors was investigated by semi-quantitative immunohistochemistry. The association of their pattern of expression with survival was evaluated by Kaplan–Meier and Cox’s proportional hazard analyses. Multivariable Cox proportional hazards models were developed to predict median 2- and 3-year RFS and 2.5- and 5-year OS. The Akaike information criterion technique and backwards stepwise procedure were used for model selections. The performance of the final Cox models was assessed with respect to calibration and discrimination.

Results

Immunohistochemical labeling for HER1 and HER2 was localized both in the cell membrane and in the cytoplasm, while HER3 labeling was observed both in the cell cytoplasm and in the nucleus. HER3 expression was inversely correlated with HER1 positivity. The expression patterns of HERs were associated with tumor differentiation. In both cohorts of patients, HER1 expression was associated with reduced relapse-free (RFS) and overall survival (OS). In HER1 positive tumors, the co-expression with nuclear HER3 was associated with better RFS and OS, compared with HER3 negative tumors or tumors expressing HER3 at cytoplasmic level. HER3 expressing tumors had a higher Geminin/MCM7 ratio than HER3 negative ones, regardless of HER1 co-expression. Multivariable analyses identified age at diagnosis, tumor site, HER1, HER3 and age at diagnosis, tumor stage, HER1, HER3, as covariates significantly associated with RFS and OS, respectively. Bootstrapping verified the good fitness of these models for predicting survivals and the optimism-corrected C-indices were 0.76 and 0.77 for RFS and OS, respectively.

Conclusions

Nuclear HER3 expression was strongly associated with favourable prognosis and allows to improve the prognostic stratification of patients with HER1 positive advanced LSCC carcinoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03081-0.

PET and SPECT Imaging of the EGFR Family (RTK Class I) in Oncology

The human epidermal growth factor receptor family (EGFR-family, other designations: HER family, RTK Class I) is strongly linked to oncogenic transformation. Its members are frequently overexpressed in cancer and have become attractive targets for cancer therapy. To ensure effective patient care, potential responders to HER-targeted therapy need to be identified. Radionuclide molecular imaging can be a key asset for the detection of overexpression of EGFR-family members. It meets the need for repeatable whole-body assessment of the molecular disease profile, solving problems of heterogeneity and expression alterations over time. Tracer development is a multifactorial process. The optimal tracer design depends on the application and the particular challenges of the molecular target (target expression in tumors, endogenous expression in healthy tissue, accessibility). We have herein summarized the recent preclinical and clinical data on agents for Positron Emission Tomography (PET) and Single Photon Emission Tomography (SPECT) imaging of EGFR-family receptors in oncology. Antibody-based tracers are still extensively investigated. However, their dominance starts to be challenged by a number of tracers based on different classes of targeting proteins. Among these, engineered scaffold proteins (ESP) and single domain antibodies (sdAb) show highly encouraging results in clinical studies marking a noticeable trend towards the use of smaller sized agents for HER imaging.

Immuno-toxicological evaluation of her1 cancer vaccine in non-human primates: a 6-month subcutaneous study

Purpose: A vaccine composition based on the extracellular domain of the human epidermal growth factor receptor 1 (HER1-ECD) and the combination of VSSP (very small size proteoliposomes) and Montanide ISA 51 adjuvants when used by intramuscular route, demonstrated promising results in preclinical studies. However, in order to avoid potential adverse events due to the use of Montanide, it is proposed to modify the vaccine formulation by using VSSP (very small size proteoliposomes) adjuvant alone, and to evaluate the quality of subcutaneously induced immune response. This study aimed to assess the immunotoxicological effects of HER1 vaccine in Cercopithecus aethiops.Materials and methods: Fifteen monkeys were randomized into four groups: Negative Control (Tris/NaCl, s.c.), Positive Control (200 µg HER1-ECD/VSSP/Montanide ISA-51 VG, i.m), Low Dose (200 µg HER1-ECD/VSSP/Tris NaCl, s.c.) and High Dose (800 µg HER1-ECD/VSSP/Tris NaCl, s.c). All monkeys received 7 doses and were daily inspected for clinical signs. Body weight, rectal temperature, cardiac and respiratory rates were measured during the study, and electrocardiographical and ophthalmological studies were performed. Humoral and cellular immune response and clinical pathology parameters were analyzed.Results: Animal's survival in the study was 100% (n = 15). Administration site reactions were observed in the Positive Control animals (n = 4). HER1 vaccine administered subcutaneously (High Dose Group) achieved good IgG antibody titers although lower than the Positive Control group, but with higher ability to inhibit HER1 phosphorylation. Conclusions: This suggests that the alternative of eliminating the use of Montanide in the HER1 vaccine preparation and the using subcutaneous route is feasible.

Exploration of a F(ab')2 Fragment as the Targeting Agent of α-Radiation Therapy: A Comparison of the Therapeutic Benefit of Intraperitoneal and Intravenous Administered Radioimmunotherapy

Refinement of treatment regimens enlisting targeted α-radiation therapy (TAT) is an ongoing effort. Among the variables to consider are the target molecule, radionuclide, dosage, and administration route. The panitumumab F(ab')₂ fragment targeting epidermal growth factor receptor tolerated modification with the TCMC chelate as well as radiolabeling with ²⁰³Pb or ²¹²Pb. Good specific activity was attained when the immunoconjugate was labeled with ²¹²Pb (9.6 ± 1.4 mCi/mg). Targeting of LS-174T tumor xenografts with the ²⁰³Pb-panitumumab F(ab')₂ demonstrated comparable amounts of uptake to the similarly radiolabeled panitumumab IgG. A dose escalation study was performed to determine an effective working dose for both intraperitoneal (i.p.) and intravenous (i.v.) injections of ²¹²Pb-panitumumab F(ab')₂. Therapeutic efficacy, with modest toxicity, was observed with 30 μCi given i.p. Results for the i.v. administration were not as definitive and the experiment was repeated with a higher dose range. From this study, 20 μCi given i.v. was selected as the effective working dose. A subsequent therapy study combined gemcitabine or paclitaxel with i.v. ²¹²Pb-panitumumab F(ab')₂, which increased the median survival (MS) of LS-174T tumor-bearing mice to 208 and 239 d, respectively. Meanwhile, the MS of mice treated with i.v. ²¹²Pb-panitumumab F(ab')₂ alone was 61 and 11 d for the untreated group of mice. In conclusion, the panitumumab F(ab')₂ fragment whether given by i.p. or i.v. injection, is a viable candidate as a delivery vector for TAT of disseminated i.p. disease.

HER1-based vaccine: Simultaneous activation of humoral and cellular immune response

The human epidermal growth factor receptor 1 (HER1) is a tumor-associated antigen that has been validated as a clinical target for several passive, non-immune therapies currently approved for the treatment of epithelial tumors. HER1 is an oncogene that not only promotes tumor progression and survival, but also immune escape. Its overexpression in some epithelial malignancies has been correlated with a poor prognosis. We developed an approach to target HER1 by specific active immunotherapy, recognizing the extracellular domain of the receptor, using a combination of VSSP and Montanide ISA 51 as adjuvants. We summarize the results obtained with this vaccine in both the preclinical and clinical settings, emphasizing the importance of the induction of both humoral and cellular responses for the success of cancer vaccines as safe therapeutic alternatives for the treatment of cancer.

FGFR1 and HER1 or HER2 co-amplification in breast cancer indicate poor prognosis

Human epidermal growth factor receptor 1 or 2 (HER1/2), and fibroblast growth factor receptor 1 (FGFR1) signaling serve critical roles in the progression of breast cancer; however, cross-talk between HER1/2 and FGFR1 signaling has not been extensively studied. In the present study, the copy number variation status of FGFR1 and HER1/2, and the clinical implications and prognostic relevance of this, were evaluated in invasive ductal breast cancer (IDC) tissue samples. Quantitative polymerase chain reaction and fluorescence in situ hybridization were used to assess gene copy number variation in IDC samples, and the clinical characteristics and survival curves of patients with IDC were analyzed. The amplification of FGFR1 was identified in 16.0% of the samples (12 of 75), of HER1 in 26.7% (20 of 75), of HER2 in 37.3% (28 of 75), and of FGFR1 and HER1/2 simultaneously in 8.0% (6 of 75). FGFR1 and HER1/2 co-amplification were significantly correlated with distant metastasis (P=0.035), recurrence (P=0.026) and decreased disease-free survival time (P=0.042). This was the case for patients undergoing endocrine therapy (P=0.002) and chemotherapy (P=0.044). Taken together, the results indicate that patients with FGFR1 and HER1/2 co-amplification may exhibit a less favorable prognosis compared with patients with either FGFR1, HER1/2 amplification or without amplification.

Anti-proliferative and pro-apoptotic effects induced by simultaneous inactivation of HER1 and HER2 through endogenous polyclonal antibodies

The human epidermal growth factor receptor (HER1) and its partner HER2 are extensively described oncogenes and validated targets for cancer therapy. However, the effectiveness of monospecific therapies targeting these receptors is hampered by resistance emergence, which is frequently associated with the upregulation of other members of HER family. Combined therapies using monoclonal antibodies or tyrosine kinase inhibitors have been suggested as a promising strategy to circumvent this resistance mechanism. We propose an alternative approach based on simultaneous inactivation of HER1 and HER2 by multi-epitope blockade with specific polyclonal antibodies induced by vaccination. Elicited antibodies impaired both receptors activation and induced their degradation, which caused the inhibition of down-signaling cascades. This effect was translated into cell cycle arrest and apoptosis induction of human tumor cells. Elicited antibodies were able to reduce the viability of a panel of human tumor lines with differential expression levels of HER1 and HER2. The most significant effects were obtained in the tumor lines with lower expression levels of both receptors. These new insights would contribute to the rational design of HER receptors targeting multivalent vaccines, as an encouraging approach for the treatment of cancer patients.

Piperlongumine downregulates the expression of HER family in breast cancer cells

HER family receptors are frequently deregulated in breast cancer and the deregulation of these receptors is associated with poor prognosis. Thus, these receptors are considered therapeutic targets. In the present study, we found that piperlongumine (PL) downregulates the expression of HER family receptors HER1, HER2, and HER3 in breast cancer cells. Downregulation of these receptors by PL is mediated through the generation of reactive oxygen species (ROS), as N-acetyl-cysteine blocks it. Interestingly, the HER2-overexpressing cell lines BT474 and SkBr3 are somewhat more sensitive to PL than the low HER2-expressing cell line MCF7. In addition, the overexpression of HER2 increases the sensitivity of MCF7 cells to PL. Collectively, our data indicate the therapeutic potential of PL in the treatment of breast cancer.

The prognostic significance of human epidermal growth factor receptor family protein expression in operable pancreatic cancer : HER1-4 protein expression and prognosis in pancreatic cancer

Background

Prognostic factors aid in the stratification and treatment of cancer. This study evaluated the prognostic significance of human epidermal growth factor receptor (HER) family members (HER1–4) expression in patients with operable pancreatic cancer.

Methods

The expression of individual HER proteins in patient tissue specimens was detected by immunohistochemistry staining. Patient follow-up time was between 1.0 and 78.1 months.

Results

Positive expression of HER1, HER2, HER3 and HER4 was detected in 41.4, 60.0, 24.3 and 65.7% of cases, respectively. Kaplan–Meier analysis revealed that HER3 positive expression was associated with decreased median survival time (12.0 vs. 25.6 months for HER3 positive and negative groups, respectively; P = 0.013). Cox’s regression confirmed that positive HER3 expression was an independent predictor of poor survival (RR = 3.684, P = 0.001). In contrast, HER4 negative patients had a significantly decreased median survival time when compared with HER4 positive patients (11.4 vs. 25.6 months, respectively; P = 0.027). However, HER4 was not an independent predictor of survival. No significant association between HER1 or HER2 expression and survival was observed (P = 0.626 & P = 0.859, respectively).

Conclusions

HER3 is an independent prognostic marker for patients with operable pancreatic cancer. HER4 may also be of potential prognostic value in this disease and deserves further attention.

The use of CrossMAb technology for the generation of bi- and multispecific antibodies

The major challenge in the generation of bispecific IgG antibodies is enforcement of the correct heavy and light chain association. The correct association of generic light chains can be enabled using immunoglobulin domain crossover, known as CrossMAb technology, which can be combined with approaches enabling correct heavy chain association such as knobs-into-holes (KiH) technology or electrostatic steering. Since its development, this technology has proven to be very versatile, allowing the generation of various bispecific antibody formats, not only heterodimeric/asymmetric bivalent 1+1 CrossMAbs, but also tri- (2+1), tetravalent (2+2) bispecific and multispecific antibodies. Numerous CrossMAbs have been evaluated in preclinical studies, and, so far, 4 different tailor-made bispecific antibodies based on the CrossMAb technology have entered clinical studies. Here, we review the properties and activities of bispecific CrossMAbs and give an overview of the variety of CrossMAb-enabled antibody formats that differ from heterodimeric 1+1 bispecific IgG antibodies.

Engineering Chimeric Receptors To Investigate the Size- and Rigidity-Dependent Interaction of PEGylated Nanoparticles with Cells

Attachment of ligands to the surface of nanoparticles (NPs) is an attractive approach to target specific cells and increase intracellular delivery of nanocargos. To expedite investigation of targeted NPs, we engineered human cancer cells to express chimeric receptors that bind polyethylene glycol (PEG) and internalize stealth NPs in a fashion similar to ligand-targeted liposomes against epidermal growth factor receptor 1 or 2 (HER1 or HER2), which are validated targets for cancer therapy. Measurement of the rate of endocytosis and lysosomal accumulation of small (80-94 nm) or large (180-220 nm) flexible liposomes or more rigid lipid-coated mesoporous silica particles in human HT29 colon cancer and SKBR3 breast cancer cells that express chimeric receptors revealed that larger and more rigid NPs were internalized more slowly than smaller and more flexible NPs. An exception is when both the small and large liposomes underwent endocytosis via HER2. HER1 mediated faster and greater uptake of NPs into cells but retained NPs less well as compared to HER2. Lysosomal accumulation of NPs internalized via HER1 was unaffected by NP rigidity but was inversely related to NP size, whereas large rigid NPs internalized by HER2 displayed increased lysosomal accumulation. Our results provide insight into the effects of NP properties on receptor-mediated endocytosis and suggest that anti-PEG chimeric receptors may help accelerate investigation of targeted stealth NPs.

Evaluation of cetuximab as a candidate for targeted α-particle radiation therapy of HER1-positive disseminated intraperitoneal disease

Although the epidermal growth factor receptor (EGFR), also known as HER1, has been studied for over a decade, it continues to be a molecule of great interest and focus of investigators for development of targeted therapies. The marketed monoclonal antibody cetuximab binds to HER1, and thus might serve as the basis for creation of imaging or therapies that target this receptor. The potential of cetuximab as a vehicle for the delivery of α-particle radiation was investigated in an intraperitoneal tumor mouse model. The effective working dose of 10 μCi of (212)Pb-cetuximab was determined from a dose (10-50 μCi) escalation study. Toxicity, as indicated by the lack of animal weight loss, was not evident at the 10 μCi dose of (212)Pb-cetuximab. A subsequent study demonstrated (212)Pb-cetuximab had a therapeutic efficacy similar to that of (212)Pb-trastuzumab (p = 0.588). Gemcitabine given 24 h prior to (212)Pb-cetuximab increased the median survival from 174 d to 283 d, but carboplatin suppressed the effectiveness of (212)Pb-cetuximab. Notably, concurrent treatment of tumor-bearing mice with (212)Pb-labeled cetuximab and trastuzumab provided therapeutic benefit that was greater than either antibody alone. In conclusion, cetuximab proved to be an effective vehicle for targeting HER1-expressing tumors with α-radiation for the treatment of disseminated intraperitoneal disease. These studies provide further evidence that the multimodality therapy regimens may have greater efficacy and benefit in the treatment of cancer patients.