Potential Therapeutic Target For Head And Neck Squamous Cell Carcinoma Research Articles

CD100-plexin-B1 induces epithelial-mesenchymal transition of head and neck squamous cell carcinoma and promotes metastasis.

Head and neck squamous cell carcinoma (HNSCC) is one of the most lethal cancers mainly due to the high rate of metastasis. Here, we find that the expression level of CD100 in HNSCC is positively correlated with the T category, pathological grade and lymph node metastasis of the tumor. The level of soluble CD100 (sCD100) is highly increased in serum of HNSCC patients, and sCD100 markedly induces the epithelial-mesenchymal transition (EMT) of HNSCC through its receptor, Plexin-B1 (PlxnB1), and promotes the metastasis in a xenograft mouse model. Furthermore, sCD100 promotes the stabilization of Snail through the regulation of the Vav1-Rac1/RhoA-p21-activated kinase pathway for the induction of EMT. Anti-CD100 antibody abolishes the CD100-induced EMT and prevents the metastasis of HNSCC, and anti-CD100 antibody also increases the drug sensitivity of HNSCC. Taken together, our study shows for the first time that CD100 induces the EMT of HNSCC and promotes the metastasis, and CD100 would be a candidate as a novel prognostic biomarker and a potential therapeutic target for HNSCC.

Abstract 351: mTOR-ERK co-targeting strategies for head and neck cancer therapy

Abstract Despite therapeutic advances in the past decade, head and neck squamous cell carcinoma (HNSCC) continues to be a major public health concern. Although recent studies of human cancer genomes identified remarkable complexity of genomic alterations in HNSCC, surprisingly, most aberrations have fallen within key driver signaling pathways. Among them, PI3K/AKT/mTOR pathway is most frequently activated in over 80% of the HNSCC patients. We showed that the majority of HNSCC lesions exhibit high levels of phosphorylated ribosomal S6 protein (pS6), key downstream target of the AKT-mTOR pathway, and that inhibition of mTOR by the use of rapamycin causes a rapid decrease in the level of pS6 and the apoptotic death of HNSCC tumor xenografts, thereby causing tumor regression. Our initial studies identified the AKT-mTOR pathway as a potential therapeutic target for HNSCC and provided strong rational to initiate multiple clinical trials. Indeed, inhibitors of PI3K/AKT/mTOR block mTOR activity and exert a beneficial response in HNSCC patients. However, therapeutic resistance was evidenced in several trials, which might be due to the activation of adaptive survival signaling in tumor cells. To explore the therapeutic option that can overcome the resistance, we performed a synthetic lethality screen in HNSCC cell lines using shRNA libraries. We found that multiple molecules involved in ERK pathway were highly represented. Furthermore, treating HNSCC cell lines harboring activated mTOR with small molecule inhibitors that target PI3K/AKT/mTOR pathway can sequentially induce ERK activation, which is consistent with the findings observed in numerous clinical trials. We demonstrated that co-targeting mTOR and ERK using trametinib, a MEK1/2 inhibitor or cetuximab, an EGFR monoclonal antibody, exhibited the synergistic effect by sensitizing HNSCC to priming with the mTOR inhibitor. Specifically, mTOR-ERK co-targeting prevented the growth of HNSCC tumor xenografts by decreasing cell proliferation, reducing lymphangiogenesis and activating apoptosis. In addition, we have recently used a phosphoproteomics approach to identify the molecular mechanisms of ERK feedback activation caused by PI3K/AKT/mTOR inhibition. Overall, our promising findings from these preclinical studies suggest that the use of mTOR-ERK co-targeting strategies may provide the novel alternative approach to achieve durable responses (cure) in HNSCC cancer patients. Citation Format: Zhiyong Wang, Esteban Delgado, Kosuke Yamaguchi, Ramiro Iglesias-Bartolomé, Panomwat Amornphimoltham, Alfredo Molinolo, Qianming Chen, J.Silvio Gutkind. mTOR-ERK co-targeting strategies for head and neck cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 351. doi:10.1158/1538-7445.AM2017-351

Implication of the Receptor Tyrosine Kinase AXL in Head and Neck Cancer Progression.

Head and neck squamous cell carcinoma (HNSCC) remains a clinical challenge and identification of novel therapeutic targets is necessary. The receptor tyrosine kinase AXL has been implicated in several tumor entities and a selective AXL small molecule inhibitor (BGB324) is currently being tested in clinical trials for patients suffering from non-small cell lung cancer or acute myeloid leukemia. Our study investigates AXL expression during HNSCC progression and its use as a potential therapeutic target in HNSCC. AXL protein expression was determined in a HNSCC cohort (n = 364) using immunohistochemical staining. For functional validation, AXL was either overexpressed or inhibited with BGB324 in HNSCC cell lines to assess proliferation, migration and invasion. We found AXL protein expression increasing during tumor progression with highest expression levels in recurrent tumors. In HNSCC cell lines in vitro, AXL overexpression increased migration as well as invasion. Both properties could be reduced through treatment with BGB324. In contrast, proliferation was neither affected by AXL overexpression nor by inhibition with BGB324. Our patient-derived data and in vitro results show that, in HNSCC, AXL is important for the progression to more advanced tumor stages. Moreover, they suggest that AXL could be a target for precision medicine approaches in this dismal tumor entity.

Drug-induced RAF dimerization is independent of RAS mutation status and does not lead to universal MEK dependence for cell survival in head and neck cancers.

Treatments for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) have limited efficacy. One potential therapeutic target for HNSCC is the RAS/RAF/MEK/ERK cascade, which is one of the major signaling pathways for HNSCC cell survival. In HNSCC, RAS can be activated either by HRAS mutation or by upstream signaling. The ABL inhibitor nilotinib acts as a weak RAF inhibitor that induces RAF dimerization and subsequent activation of MEK/ERK in other cancer cell lines with activated RAS, leading to an unexpected dependence on MEK/ERK for cell survival. We hypothesized that nilotinib and the MEK inhibitor MEK162 would be synergistic in HNSCC cell lines owing to the frequent activation of RAS. We treated HNSCC cell lines with nilotinib and performed immunoblotting and cell-viability experiments. We used an orthotopic mouse model to assess synergistic effects in vivo. Nilotinib induced significant BRAF-CRAF heterodimerization and ERK activation irrespective of RAS mutation status. In cell-viability assays, nilotinib synergized with MEK162. MEK162 alone induced G1 arrest that was minimally enhanced by nilotinib. In the mouse model, treatment with MEK162 alone or combined with nilotinib led to tumor growth inhibition. In HNSCC, nilotinib-induced RAF dimerization is independent of RAS mutation status, but this dimerization does not lead to MEK dependence for cell survival in all HNSCC cell lines. MEK inhibition alone leads to decreased proliferation both in vitro and in vivo. Although nilotinib has some synergistic effects with MEK162, other agents may be more effective against HNSCC when combined with MEK162.

Cytoplasmic DRAK1 overexpressed in head and neck cancers inhibits TGF-β1 tumor suppressor activity by binding to Smad3 to interrupt its complex formation with Smad4.

Head and neck squamous cell carcinoma (HNSCC) is an extremely aggressive cancer with a poor prognosis and low patient survival. Because chemotherapy for advanced HNSCC is often ineffective, discovering new therapeutic targets that are important for HNSCC development and progression and elucidating their molecular mechanisms are required. In the present study, we describe the role of DRAK1 (death-associated protein kinase-related apoptosis-inducing kinase 1) as a novel negative regulator of the transforming growth factor-β (TGF-β) tumor suppressor signaling pathway for the first time in human HNSCC cells. DRAK1 was significantly overexpressed in primary human HNSCCs and in HNSCC cell lines. Through gain- and loss-of-function experiments, we demonstrated that the DRAK1 expression level regulated TGF-β1-induced transcriptional activity and expression of the tumor suppressor gene p21(Waf1/Cip1). DRAK1 depletion enhanced TGF-β1-induced growth inhibition in vitro and suppressed tumorigenicity in xenograft models in vivo. Mechanistically, DRAK1 was predominantly localized in the cytoplasm and bound to Smad3, thereby interrupting Smad3/Smad4 complex formation, which is the core process for the induction of tumor suppressor genes by TGF-β1. Thus, our findings suggest that cytoplasmic DRAK1 increases tumorigenic potential through inhibition of TGF-β1-mediated tumor suppressor activity in HNSCC cells and may be a potential therapeutic target for HNSCCs.

Abstract 2450: Either pan class I PI3K inhibitor or PI3K alpha selective inhibitor sensitizes head and neck squamous cell carcinoma cells to Erlotinib, an EGFR TKI.

Abstract The epidermal growth factor receptor (EGFR) is overexpressed in 90% of head and neck squamous cell carcinoma (HNSCC), and is correlated with poor prognosis. EGFR is therefore a potential therapeutic target for HNSCC. However, most HNSCC patients do not respond well to small molecular EGFR inhibitors. One of the possible mechanisms of EGFR TKI resistance is compensatory collateral activation of PI3K/Akt pathway. This study sought to explore whether NVP-BKM120, a selective pan class I PI3 kinase inhibitor, and NVP-BYL719, a novel PI3 kinase alpha selective inhibitor, may reverse the resistance of HNSCC cells toward erlotinib, an EGFR TKI. Cells were treated with the PI3K inhibitors, either BKM120 or BYL719, alone, erlotinib alone, or in combination, and viability was measured at 72 hours with MTT assay. Combination effect was evaluated by median effect analysis. Synergism, indicated by a combination index (CI) value <1, were seen in all five cell lines (SAS, HSC3, UMCC1, CA922 and FaDu) studied. By immunoblotting analysis, combination of Erlotinib and either PI3K inhibitor resulted in dowregulation of p-EGFR and p-AKT expression in SAS cells. When SAS and HSC3 cells were treated with erlotinib in combination with either BKM120 or BYL719, an additional increase in the subG1 population by flow cytometry analysis were observed, indicating an increase of apoptotic cell death. Our data suggest that additional PI3K blockade might be an effective strategy to overcome resistance of HNSCC cells toward EGFR TKIs, and the beneficial effect is similar between pan Class I PI3K inhibitor and PI3K alpha selective inhibitor. (The study was supported by the grant of DOH101-TD-B-111-001). Citation Format: Ming Gao, Yen-Shen Lu, Li-Ping Hsiao, Suz Wen Chen, Ann-Lii Cheng. Either pan class I PI3K inhibitor or PI3K alpha selective inhibitor sensitizes head and neck squamous cell carcinoma cells to Erlotinib, an EGFR TKI. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2450. doi:10.1158/1538-7445.AM2013-2450

Ubiquitin-specific protease 4 promotes TNF-α-induced apoptosis by deubiquitination of RIP1 in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common type of cancer. Better understanding of molecular aberrations associated with HNSCC might identify new diagnostic and therapeutic strategies for this disease. In this study, we found ubiquitin-specific protease 4 (USP4) was significantly upregulated in HNSCC. USP4 negatively regulates RIP1-mediated NF-κB activation and promotes TNF-α-induced apoptosis in FaDu cells. USP4 directly interacts with receptor-interacting protein 1 (RIP1) and deubiquitinates K63-linked ubiquitination from RIP1. Therefore, our results indicate that USP4 has tumor suppressor roles in HNSCC and suggest USP4 as a potential therapeutic target for HNSCC. Structured summary of protein interactionsRIP1 physically interacts with USP4 by anti tag coimmunoprecipitation (View Interaction: 1, 2, 3)RIP1 physically interacts with USP4 by anti bait coimmunoprecipitation (View interaction)

Elevated expression of iASPP in head and neck squamous cell carcinoma and its clinical significance

iASPP is shown to be elevated in several cancers. However, the role of iASPP in head and neck squamous cell carcinoma (HNSCC) remains unknown. We have investigated iASPP expression in HNSCC tissue and cell lines and evaluated its prognostic significance in HNSCC. The expression of iASPP in 109 primary HNSCC tissue specimens was examined by immunohistochemistry and its association with clinicopathological parameters and prognosis was analyzed. Additionally, expression status of iASPP in 16 paired HNSCC tissues and 7 HNSCC cell lines was evaluated by quantitative real-time PCR (qPCR) and immunoblotting. The protein and mRNA expression of iASPP were increased in HNSCC tissues and cell lines. Immunohistochemical staining indicated iASPP was detected in both cytoplasm and nucleus. Importantly, overexpression of cytoplasmic and nuclear iASPP was significantly associated with T classification (p = 0.002 and p = 0.033, respectively), clinical stage (p < 0.001 and p = 0.004), lymph node metastasis (p = 0.001 and p < 0.001), and recurrence (both p < 0.001). Survival analysis demonstrated high iASPP expression significantly correlated with shorter disease-free survival (DFS) (both p < 0.001 for cytoplasmic and nuclear expression) and overall survival (OS) (both p < 0.001 for cytoplasmic and nuclear expression). Multivariate analysis revealed that cytoplasmic iASPP was the only independent prognostic factor for HNSCC patients. iASPP expression is elevated in HNSCC tissues and cell lines, which suggests iASPP may contribute to the malignant progression of HNSCC, and serves as a novel prognostic marker and a potential therapeutic target in HNSCC.

Abstract 3338: Characterization of glucose transporter 3 in head and neck cancer initiating cells

Abstract Background: Head and Neck squamous cell carcinoma (HNSCC) is a lethal cancer with clinical, pathological, phenotypical and biological heterogeneity. Cancer initiating cells (CICs) exhibit self-renewal and promote tumor progression capacity. We have also identified the subpopulation of head and neck cancer initiating cells (HN-CICs), and observed the upregulation of Glucose Transporter 3(Glut3) in HN-CICs by differential systemic analyses. However, the role of Glut3 in HN-CICs metabolism alternation remains unclear. Herein we determined the critical role of Glut3, a novel CICs marker, in the maintenance of stemness characteristics and tumorigenic phenotype of HN-CICs. Methods: Stable overexpression and knockdown of Glut3 expression in HNSCCs and HN-CICs was achieved by lentiviral-mediated system. Consequently, we elucidated the stemness properties and tumorigenicity of HNSCCs and HN-CICs with Glut3 down-regulation. Consequently, we investigated the role of Glut3 in metabolism regulation of cancer initiation cells. Results: Lentiviral knockdown of Glut3 significantly reduced the self-renewal ability and cancer initiation cell marker Grp78 expression in HN-CICs. Additionally, down-regulation of Glut3 enhanced the differentiation capability but inversely diminished “stemness” gene expression of HN-CICs. Of note, knockdown of Glut3 lessened tumorigenicity of HN-CICs both in vitro. Conclusion: We showed that Glut3 contributes to the maintenance of stemness and tumorigenicity of HN-CICs. In addition, the expression of Glut3 was involved in HN-CICs metabolism. Overall, silencing Glut3 might be a potential therapeutic target for HNSCC by eliminating CICs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3338. doi:1538-7445.AM2012-3338

CD133/Src Axis Mediates Tumor Initiating Property and Epithelial-Mesenchymal Transition of Head and Neck Cancer

BackgroundHead and Neck squamous cell carcinoma (HNSCC) is a human lethal cancer with clinical, pathological, phenotypical and biological heterogeneity. Caner initiating cells (CICs), which are responsible for tumor growth and coupled with gain of epithelial-mesenchymal transition (EMT), have been identified. Previously, we enriched a subpopulation of head and neck cancer initiating cells (HN-CICs) with up-regulation of CD133 and enhancement of EMT. Others demonstrate that Src kinase interacts with and phosphorylates the cytoplasmic domain of CD133. However, the physiological function of CD133/Src signaling in HNSCCs has not been uncovered.Methodology/Principal FindingHerein, we determined the critical role of CD133/Src axis modulating stemness, EMT and tumorigenicity of HNSCC and HN-CICs. Initially, down-regulation of CD133 significantly reduced the self-renewal ability and expression of stemness genes, and promoted the differentiation and apoptotic capability of HN-CICs. Additionally, knockdown of CD133 in HN-CICs also lessened both in vitro malignant properties including cell migration/cell invasiveness/anchorage independent growth, and in vivo tumor growth by nude mice xenotransplantation assay. In opposite, overexpression of CD133 enhanced the stemness properties and tumorigenic ability of HNSCCs. Lastly, up-regulation of CD133 increased phosphorylation of Src coupled with EMT transformation in HNSCCs, on the contrary, silence of CD133 or treatment of Src inhibitor inversely abrogated above phenotypic effects, which were induced by CD133 up-regulation in HNSCCs or HN-CICs.Conclusion/SignificanceOur results suggested that CD133/Src signaling is a regulatory switch to gain of EMT and of stemness properties in HNSCC. Finally, CD133/Src axis might be a potential therapeutic target for HNSCC by eliminating HN-CICs.

Abstract 3359: Glucose regulated protein78, a putative head and neck cancer initiating cells marker

Abstract Background: Head and neck squamous cell carcinoma (HNSCC) is a highly lethal cancer that contains cellular and functional heterogeneity. Previously, we enriched a subpopulation of highly tumorigenic head and neck cancer initiating cells (HN-CICs) from HNSCC cells (HNSCCs) using tumor sphere formation approach. GRP78, a stress-inducible endoplasmic reticulum (ER) chaperone, has been reported to play a role in the maintenance of embryonic stem cells and was up-regulated in enriched HN-CICs. However, the molecular mechanisms mediated by GRP78 to operate the physiological characteristics in HN-CICs remain unclear. Herein, we determined the critical role of GRP78 in the maintenance of stemness characteristics and tumorigenic phenotype in HNSCCs. Methods: First, Affymatrix microarray and two-dimensional differential gel electrophoresis (2-D DIGE) proteomic analyses were applied to identify GRP78 and membrane associated GRP78 (memGRP78) as a putative marker of HN-CICs. Flow cytometry cell sorting was used to isolate memGRP78+ cells and memGRP78− cells for evaluating CICs properties. Down-regulation of GRP78 expression in HNSCCs and HN-CICs were achieved by lentiviral-mediated small hairpin RNA interference (shRNAi), and the stemness characteristics in GRP78-knockdown HN-CICs were elucidated. In addition, in vitro tumorigenic properties between GRP78-knockdown and control HN-CICs were determined. The in vivo tumorigenicity of GRP78-knockdown HN-CICs was evaluated by xenotransplantation assay. Finally, we examined the correlation on expression of GRP78 and stemness genes in HNSCC patient tissues by immunohistochemical staining. Results: We identified that GRP78/memGRP78 was significantly up-regulated in enriched HN-CICs. Subsequently, memGRP78+ HNSCCs displayed CICs properties. Lentiviral mediated knockdown of GRP78 significantly reduced expression of stemness genes in HN-CICs and HNSCCs, but enhanced the differentiation capability of HN-CICs. Overall, down-regulation of GRP78 lessened tumorigenicity of HN-CICs both in vitro and in vivo. Conclusion: Our studies first elucidated the crucial role of GRP78 in the maintenance of stemness and tumorigenicity of HN-CICs. Notably, targeting GRP78 signaling might be a potential therapeutic target for HNSCC by eliminating CICs and memGRP78 could be a novel surface biomarker for isolation HN-CICs. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3359.

Targeting Polo-Like Kinase 1 Enhances Radiation Efficacy for Head-and-Neck Squamous Cell Carcinoma

To investigate the efficacy of targeting polo-like kinase 1 (Plk1) combined with ionizing radiotherapy (RT) for head-and-neck squamous cell carcinoma (HNSCC). Polo-like kinase 1 messenger ribonucleic acid (mRNA) was targeted by small interfering RNA (siRNA) transfection into the FaDu HNSCC cell line; reduction was confirmed using quantitative real-time polymerase chain reaction. The cellular effects were assessed using [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium], clonogenic, flow cytometric, and caspase assays. In vivo efficacy of siPlk1 was evaluated using mouse xenograft models. Small interfering Plk1 significantly decreased Plk1 mRNA expression, while also increasing cyclin B1 and p21(Waf1/CIP1) mRNA levels after 24 h. This depletion resulted in a time-dependent increase in FaDu cytotoxicity, which was enhanced by the addition of RT. Flow cytometric and caspase assays demonstrated progressive apoptosis, DNA double-strand breaks (gamma-H2AX), G2/M arrest, and activation of caspases 3 and 7. Implantation of siPlk1-treated FaDu cells in severe combined immunodeficient mice delayed tumor formation, and systemic administration of siPlk1 inhibited tumor growth enhanced by RT. These data demonstrate the suitability of Plk1 as a potential therapeutic target for HNSCC, because Plk1 depletion resulted in significant cytotoxicity in vitro and abrogated tumor-forming potential in vivo. The effects of Plk1 depletion were enhanced with the addition of RT, indicating that Plk1 represents an important potential radiation sensitizer for HNSCC.

Rap1 Stabilizes β-Catenin and Enhances β-Catenin–Dependent Transcription and Invasion in Squamous Cell Carcinoma of the Head and Neck

In head and neck squamous cell carcinoma (HNSCC) cells, Rap1 shuttles between the nucleus and cytoplasm. Prior findings suggested that Rap1 may modulate the beta-catenin-independent Wnt pathway in some settings, but the role of Rap1 in beta-catenin-dependent Wnt signaling remains undefined. We observed that beta-catenin bound to active Rap1 in vitro and Rap1 activated beta-catenin/T-cell factor (TCF)-dependent transcription. Immunofluorescence studies showed that ectopic expression of Rap1 increased nuclear translocation of beta-catenin. Overexpression of active Rap1 facilitated an increase in beta-catenin-mediated transcription that was abrogated by dominant-negative TCF4. Conversely, small interfering RNA-mediated inhibition of endogenous Rap1 expression inhibited beta-catenin/TCF-mediated transcription as well as invasion of HNSCC. Furthermore, inhibition of Rap1 expression downregulated the expression of matrix metalloproteinase 7, a transcriptional target of beta-catenin/TCF. In HNSCC cells stably transfected with beta-catenin or treated with lithium chloride or Wnt3A to stabilize endogenous beta-catenin, inhibition of Rap1 expression led to decreases in the free pool of beta-catenin. Immunohistochemical studies of tissue from HNSCC patients revealed that increased beta-catenin intensity correlated with higher tumor stage. Furthermore, the prognostic effect of active Rap1 on tumor N stage was found to depend on cytosolic beta-catenin expression (P < 0.013). When beta-catenin is high, higher Rap1GTP intensity is associated with more advanced N stage. The findings suggest that Rap1 enhances beta-catenin stability and nuclear localization. In addition to indicating that Rap1 has a significant role in regulating beta-catenin and beta-catenin-dependent progression to more advanced N-stage lesions, these data highlight Rap1 as a potential therapeutic target in HNSCC.

Aurora kinase A inhibition and paclitaxel as targeted combination therapy for head and neck squamous cell carcinoma

Aurora kinase A (AURKA) is amplified with varying incidence in multiple human cancers including head and neck squamous cell carcinoma (HNSCC). We investigated whether AURKA is a potential therapeutic target in HNSCC. We conducted an immunohistochemical analysis of AURKA expression in paired normal and tumor samples (n = 63). HNSCC cells treated with siRNA specific for AURKA were assessed for AURKA mRNA and protein expression levels by reverse transcriptase-polymerase chain reaction and Western blot analysis. Tumor cells treated with siRNA and paclitaxel were assessed for cell proliferation by MTT assay and for cell cycle distribution by flow cytometry. AURKA expression was higher in tumor than in adjacent normal in most (85%) of the samples analyzed. HNSCC cells and primary tumors revealed high expression levels of AURKA. Most primary tumors also showed high kinase activity of the enzyme. Targeted AURKA inhibition increased the sub-G1 cell fraction, with a concomitant reduction in the G1 cell population, indicating induction of apoptosis and thus markedly suppressed proliferation of HNSCC cells. Combining siRNA-induced AURKA inhibition with 5 to 10 nM paclitaxel synergistically enhanced apoptosis induction. AURKA is a potential therapeutic target for HNSCC. Further investigation of small-molecule AURKA inhibitors as therapeutic agents is warranted.

Uptake of the anti-epidermal growth factor receptor (EGFR) antibody EMD 72000 in tumors of subjects with head and neck squamous cell carcinoma (HNSCC)

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 antibody. Tumor:background ratios (Tu:B) were obtained from SPECT and normalized time-activity curves for the heart, liver, and WB were obtained from planar images. Tumor expression of EGFR was determined by immunohistochemistry. Results: Fourteen subjects with stage 3 or 4 EGFR+ HNSCC participated in the study. There were no major differences in either EGFR expression or EMD 72000 PK between the study groups, and PK parameters were similar to those seen in other studies. Tumor uptake of EMD 72000 increased in both groups for 24 h. Although Tu:B was greater in group A, which indicated substantial tumor accumulation, peak Tu:B (A 2.9; B 2.4) did not differ significantly between groups. Bloodpool activities were comparable between groups; liver accumulation was slightly but not significantly lower in B. After 48 h, WB retention in A (84%) was significantly (P < 0.05) lower than in B (94%). Conclusions: Tumor accumulation of EMD 72000 suggests potential applications for this antibody in the treatment of HNSCC. However, a single 200-mg dose of EMD 72000 did not completely saturate EGFR in this study. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Merck KGaA Merck KGaA

Uptake of the anti-epidermal growth factor receptor (EGFR) antibody EMD 72000 in tumors of subjects with head and neck squamous cell carcinoma (HNSCC)

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...