Sensory nerve release of CGRP increases tumor growth in HNSCC by suppressing TILs

BACKGROUND

Perineural invasion (PNI) and nerve density within the tumor microenvironment (TME) have long been associated with worse outcomes in head and neck squamous cell carcinoma (HNSCC). This prompted an investigation into how nerves within the tumor microenvironment affect the adaptive immune system and tumor growth.

METHODS

We used RNA sequencing analysis of human tumor tissue from a recent HNSCC clinical trial, proteomics of human nerves from HNSCC patients, and syngeneic orthotopic murine models of HPV-unrelated HNSCC to investigate how sensory nerves modulate the adaptive immune system.

FINDINGS

Calcitonin gene-related peptide (CGRP) directly inhibited CD8 T cell activity in vitro, and blocking sensory nerve function surgically, pharmacologically, or genetically increased CD8 and CD4 T cell activity in vivo.

CONCLUSIONS

Our data support sensory nerves playing a role in accelerating tumor growth by directly acting on the adaptive immune system to decrease Th1 CD4 T cells and activated CD8 T cells in the TME. These data support further investigation into the role of sensory nerves in the TME of HNSCC and points toward the possible treatment efficacy of blocking sensory nerve function or specifically inhibiting CGRP release or activity within the TME to improve outcomes.

FUNDING

1R01DE028282-01, 1R01DE028529-01, 1P50CA261605-01 (to S.D.K.), 1R01CA284651-01 (to S.D.K.), and F31 DE029997 (to L.B.D.).

Comparative Evaluation of Implant-Protected Occlusion in Partially Edentulous Fixed Restoration Using Qualitative and Quantitative Assessment - A Prospective Clinical Trial

OBJECTIVES

To compare and evaluate the occlusal variability/discrepancy recorded using qualitative (articulating paper) and quantitative (T-scan) techniques in partially edentulous implant-supported restorations.

MATERIALS AND METHODS

A total of 20 patients in the age group of 25-61 yrs participated in this study. All the patients had more than one tooth replaced with implant-supported prosthesis. After three months of restoration, occlusion reevaluated was carried out using qualitative (articulating paper) and quantitative (T-scan). T-scan data were used to measure implant occlusion time, occlusion time, and the relative occlusal force (ROFs) on implant prosthesis. And the data were statistically evaluated.

RESULTS

The T-scan values showed high points on the implants in most of the patients, which could not be evaluated by that of articulating paper outcomes.

CONCLUSION

The occlusal harmony achieved from using qualitative analysis of articulating paper was not supported by the finding of the quantitative analysis (T-scan). Also the T-scan provided the time interval of occlusion of the implant-supported restorations, which would help in better defining the implant-protected occlusal.

CLINICAL RELEVANCE

The T-scan occlusal analysis system provides ROF and time intervals of occlusal contact. This allows accurate occlusal equilibration of implant-supported restoration according to implant protected occlusal concept.

Selective targeting of IL2Rβγ combined with radiotherapy triggers CD8- and NK-mediated immunity, abrogating metastasis in HNSCC

The implementation of cancer immunotherapies has seen limited clinical success in head and neck squamous cell carcinoma (HNSCC). Interleukin-2 (IL-2), which modulates the survival and functionality of lymphocytes, is an attractive target for new immunotherapies but one that is limited by presence of regulatory T cells (Tregs) expressing the high-affinity IL-2Rα. The bispecific immunocytokine PD1-IL2v preferentially delivers IL-2 signaling through IL-2Rβγ on PD-1-expressing cells. Selectively targeting the intermediate-affinity IL-2Rβγ can be leveraged to induce anti-tumor immune responses in effector T cells and natural killer (NK) cells while limiting the negative regulation of IL-2Rα activation on Tregs. Using radiation therapy (RT) in combination with PD1-IL2v improves local tumor control and survival, and controls metastatic spread in orthotopic HNSCC tumor models. PD1-IL2v drives systemic activation and expansion of circulating and tumor-infiltrating cytotoxic T cells and NK cells while limiting Treg-mediated immunosuppression. These data show that PD1-L2v induces durable systemic tumor control in HNSCC.

EphB4 and ephrinB2 act in opposition in the head and neck tumor microenvironment

Differential outcomes of EphB4-ephrinB2 signaling offers formidable challenge for the development of cancer therapeutics. Here, we interrogate the effects of targeting EphB4 and ephrinB2 in head and neck squamous cell carcinoma (HNSCC) and within its microenvironment using genetically engineered mice, recombinant constructs, pharmacologic agonists and antagonists. We observe that manipulating the EphB4 intracellular domain on cancer cells accelerates tumor growth and angiogenesis. EphB4 cancer cell loss also triggers compensatory upregulation of EphA4 and T regulatory cells (Tregs) influx and their targeting results in reversal of accelerated tumor growth mediated by EphB4 knockdown. EphrinB2 knockout on cancer cells and vasculature, on the other hand, results in maximal tumor reduction and vascular normalization. We report that EphB4 agonism provides no additional anti-tumoral benefit in the absence of ephrinB2. These results identify ephrinB2 as a tumor promoter and its receptor, EphB4, as a tumor suppressor in HNSCC, presenting opportunities for rational drug design.

Loss of cancer cell STAT1 improves response to radiation therapy and promotes T cell activation in head and neck squamous cell carcinoma

Resistance to radiation therapy (RT) remains an obstacle in HPV-negative head and neck squamous cell carcinomas (HNSCCs)-even with a combined RT-immunotherapy approach. Jak-Stat proteins have long been studied for both their immune regulatory role in the host immune response as well as their cancer cell signaling role in shaping the tumor microenvironment (TME). Here, we identify STAT1 as a mediator of radioresistance in HPV-negative preclinical mouse models of HNSCC, by which knockout of STAT1 in the cancer cell (STAT1 KO)-but not in the host-resulted in decreased tumor growth alongside increased immune activation. We show that RT increases STAT1/pSTAT1 expression, which may act as a marker of radioresistance. Whereas RT increased JAK-STAT and interferon (IFN) signaling, transcriptomic analysis revealed that STAT1 KO in the cancer cell resulted in decreased expression of IFN-associated genes of resistance. In vitro experiments showed that STAT1 KO increased T cell chemoattraction and decreased baseline growth. These results indicate that STAT1 may serve a tumor-promoting role in the cancer cell and will inform biomarker development and treatment regimens for HNSCC incorporating RT.

The effects of ephrinB2 signaling on proliferation and invasion in glioblastoma multiforme

The aggressive nature of glioblastoma multiforme (GBM) may be attributed to the dysregulation of pathways driving both proliferation and invasion. EphrinB2, a membrane-bound ligand for some of the Eph receptors, has emerged as a critical target regulating these pathways. In this study, we investigated the role of ephrinB2 in regulating proliferation and invasion in GBM using intracranial and subcutaneous xenograft models. The Cancer Genome Atlas analysis suggested high transcript and low methylation levels of ephrinB2 as poor prognostic indicators in GBM, consistent with its role as an oncogene. EphrinB2 knockdown, however, increased tumor growth, an effect that was reversed by ephrinB2 Fc protein. This was associated with EphB4 receptor activation, consistent with the data showing a significant decrease in tumor growth with ephrinB2 overexpression. Mechanistic analyses showed that ephrinB2 knockdown has anti-invasive but pro-proliferative effects in GBM. EphB4 stimulation following ephrinB2 Fc treatment in ephrinB2 knockdown tumors was shown to impart strong anti-proliferative and anti-invasive effects, which correlated with decrease in PCNA, p-ERK, vimentin, Snail, Fak, and increase in the E-cadherin levels. Overall, our study suggests that ephrinB2 cannot be used as a sole therapeutic target. Concomitant inhibition of ephrinB2 signaling with EphB4 activation is required to achieve maximal therapeutic benefit in GBM.

Abstract 5035: Blockade of EphB4-ephrin-B2 interaction remodels the tumor immune microenvironment in head and neck cancers

Introduction: Identifying targets in the tumor microenvironment (TME) that act as barriers to an effective anti-tumor immune response has become an area of intense investigation. In the current study, we established EphB4-ephrin-B2 signaling as a key pathway that regulates both innate and adaptive arms of the immune system. Eph receptor tyrosine kinases and their membrane-bound ephrin ligands have been implicated in human malignancies and in immune cell development, migration, and activation in inflammatory models. However, direct evidence that supports the role of Eph-ephrin interaction in cancer-related immune response is lacking. We hypothesized that EphB4-ephrin-B2 interaction regulates TME by sustaining immunosuppressive cells-Tregs and TAMs thus negatively impacting the functional ability of CD8 T cells.

Materials and methods: We used orthotopic models of head and neck squamous cell carcinoma to determine the role of EphB4-ephrin-B2 interaction in tumor immune microenvironment. Mice were treated with control agent or an EphB4-ephrin-B2 blocker in the absence or presence of radiation (RT). Tumor immune cell infiltrates were analyzed using mass cytometry and flow cytometry applications. ELISA or multiplex cytokine array were utilized to determine circulating cytokine/chemokine levels in plasma.

Results: We observed that inhibition of EphB4-ephrin-B2 signaling in vivo significantly reduced tumor growth and decreased intratumoral Tregs, TAMs, and increased the activation of Teffector cells, without affecting CD4 T cell numbers. This was correlated with decreased Treg proliferation and activation when EphB4-ephrin-B2 signaling is inhibited. Since RT remains the mainstay in treatment of head and neck squamous cell cancer (HNSCC) patients, we combined EphB4-ephrin-B2 inhibitor with RT in our tumor model and observed further increase in CD8 and CD4 T cell infiltrates and activation status, and a significant decline in circulating TGF-β1 levels and an increase in CXCL10 levels compared to the control group. A significant reduction of TAMs, favoring a polarization towards an anti-tumoral M1 phenotype, was also observed in EphB4-ephrin-B2 inhibitor+RT group. We also compared the efficacy of combining EphB4-ephrin-B2 inhibitor with RT to anti-PDL1+RT in an in vivo model known to develop resistance to anti-PDL1+RT therapy. Our data demonstrated that combining EphB4-ephrin-B2 inhibitor with RT was equally effective to that of anti-PDL1+RT in terms of anti-tumor growth response.

Conclusions: Our study provides the first insight into a novel role for EphB4-ephrin-B2 interaction in modulating tumor immune microenvironment in HNSCC. Our findings present a potential alternative in the form of EphB4-ephrin-B2 targeted therapeutics that can be tested in clinical trials in combination with RT for HNSCC patients.

Citation Format: Shilpa Bhatia, Ayman Oweida, Shelby Lennon, Laurel Darragh, Sanjana Bukkapatnam, Benjamin Van Court, David Raben, Natalie Serkova, Antonio Jimeno, Eric Clambey, Elena Pasquale, Sana Karam. Blockade of EphB4-ephrin-B2 interaction remodels the tumor immune microenvironment in head and neck cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5035.

Resistance to Radiotherapy and PD-L1 Blockade Is Mediated by TIM-3 Upregulation and Regulatory T-Cell Infiltration

Purpose: Radiotherapy (RT) can transform the immune landscape and render poorly immunogenic tumors sensitive to PD-L1 inhibition. Here, we established that the response to combined RT and PD-L1 inhibition is transient and investigated mechanisms of resistance.Experimental Design: Mechanisms of resistance to RT and PD-L1 blockade were investigated in orthotopic murine head and neck squamous cell carcinoma (HNSCC) tumors using mass cytometry and whole-genome sequencing. Mice were treated with anti-PD-L1 or anti-TIM-3 alone and in combination with and without RT. Tumor growth and survival were assessed. Flow cytometry was used to assess phenotypic and functional changes in intratumoral T-cell populations. Depletion of regulatory T cells (Treg) was performed using anti-CD25 antibody.Results: We show that the immune checkpoint receptor, TIM-3, is upregulated on CD8 T cells and Tregs in tumors treated with RT and PD-L1 blockade. Treatment with anti-TIM-3 concurrently with anti-PD-L1 and RT led to significant tumor growth delay, enhanced T-cell cytotoxicity, decreased Tregs, and improved survival in orthotopic models of HNSCC. Despite this treatment combination, the response was not durable, and analysis of relapsed tumors revealed resurgence of Tregs. Targeted Treg depletion, however, restored antitumor immunity in mice treated with RT and dual immune checkpoint blockade and resulted in tumor rejection and induction of immunologic memory.Conclusions: These data reveal multiple layers of immune regulation that can promote tumorigenesis and the therapeutic potential of sequential targeting to overcome tumor resistance mechanisms. We propose that targeted Treg inhibitors may be critical for achieving durable tumor response with combined radiotherapy and immunotherapy. Clin Cancer Res; 24(21); 5368-80. ©2018 AACR.

Role of EphB3 Receptor in Mediating Head and Neck Tumor Growth, Cell Migration, and Response to PI3K Inhibitor

Eph proteins have emerged as critical drivers affecting tumor growth and progression in human malignancies. Our The Cancer Genome Atlas (TCGA) data analysis showed that EphB3, a receptor tyrosine kinase, is frequently coamplified with PIK3CA in head and neck squamous cell carcinoma (HNSCC). We therefore hypothesized that EphB3 amplification plays a protumorigenic role in HNSCC and that EphB3 and PIK3CA are cooperating oncogenes that contribute toward its pathogenesis. This hypothesis was not experimentally supported, because EphB3 knockdown failed to alter HNSCC tumor cell growth in vitro or in vivo with an orthotopic model. However, responsiveness of EphB3 knockdown tumors to the PI3K inhibitor, BKM120, was significantly decreased in terms of both tumor growth delay and survival. This is correlated with an increase in prosurvival proteins, S6 and BcL-XL, in the EphB3 shRNA tumors treated with BKM120 compared with controls. We further observed that EphB3 knockdown resulted in increased migration in vitro and increased EMT gene signature in vivo To explain these results, we examined EphB3 phosphorylation levels in HNSCC at baseline. Although total EphB3 levels were high, we found low phospho-EphB3 levels in HNSCCs. Forced EphB3 phosphorylation with an ephrin-B2-Fc fusion protein resulted in decreased HNSCC migration and cell growth, and enhanced response to BKM120 in vitro These data collectively indicate that progression of HNSCC selects for low/inhibited EphB3 activity to enhance their survival and migratory abilities and decrease response to PI3K signaling. Therefore, strategies focused on activating EphB3 might be helpful to inhibit tumor growth and enhance sensitivity to PI3K inhibitors in HNSCC. Mol Cancer Ther; 17(9); 2049-59. ©2018 AACR.

Abstract 4173: Inhibition of EphB4-ephrinB2 signaling increases efficacy of radiation in pancreatic ductal adenocarcinoma

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer related death in the United States. Survival rates are dismal, at only 8% five year survival. Radiation is one treatment option for PDAC, although historically its efficacy has been controversial. Our research goal is to improve the efficacy of radiation for PDAC patients. An ancillary study of the recent LAP07 trial showed that patients with neutrophilia were more resistant to chemoradiation. Additionally, when patients with systemic inflammation were excluded, one year local control was 80% in the chemoradiation arm compared to 54% in the chemotherapy arm. The EphB4 receptor and ephrinB2 ligand have been shown to play a role in neutrophil mobilization from the bone marrow and infiltration into melanoma tumors. We hypothesize that inhibition of EphB4-ephrinB2 signaling will enhance the efficacy of radiation in PDAC by reducing inflammation by neutrophils.

Materials/Methods: To study tumor growth delay, Athymic nude mice were implanted in the flank with a patient derived xenograft (PDX) model of PDAC. To inhibit EphB4-ephrinB2 signaling, mice were administered with 20mg/kg of B11, a human single chain Fv antibody fragment against ephrinB2. Tumors were irradiated with 12Gy and volume was monitored by caliper. For mechanistic studies, C57/BL6 mice were injected in the flank with 10^6 FC1242 cells, which are derived from the pancreata of KPC mice. To inhibit EphB4-ephrinB2 signaling, mice received a hydrodynamic tail vein injection of 20ug/2mL TNYL-RAW-Fc plasmid. TNYL-RAW is a peptide antagonist of EphB4, and it is fused to human Fc. Tumors were irradiated with 12Gy and harvested four days later for flow cytometry analysis. Blood was also collected at various time points and analyzed by blood film white blood cell differential and flow for neutrophils. Plasmid transduction efficiency was confirmed by analyzing plasma samples collected at different time-points on an Fc protein-based ELISA assay.

Results: We observed a significant tumor growth delay in PDX implanted mice who received B11 and radiation. An ELISA for human Fc confirmed transduction of the TNYL-RAW-Fc plasmid in FC1242 tumor bearing mice. Flow analysis on FC1242 tumors showed a significant decrease in percentage of infiltrating neutrophils when treated with TNYL-RAW and radiation, and blood film white blood cell differential and flow analysis on blood showed a significant decrease in circulating neutrophils in the same mice.

Conclusions: Our findings support the hypothesis that EphB4-ephrinB2 signaling contributes to inflammation by neutrophils in PDAC, and inhibiting this signaling will increase the efficacy of radiation. This data can contribute toward a clinical trial design for combination therapy of EphB4-ephrinB2 inhibition and radiation in patients with pancreatic ductal adenocarcinoma.

Citation Format: Shelby Lennon, Shilpa Bhatia, Ayman Oweida, Jaspreet Sharma, Andy Phan, Sanjana Bukkapatnam, Nomin Uyanga, Todd Pitts, Stephen Leong, Karyn Goodman, David Raben, Elena Pasquale, Jorge Martinez-Torrecuadrada, Sana Karam. Inhibition of EphB4-ephrinB2 signaling increases efficacy of radiation in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4173.

Abstract 2946: Role of EphB3 receptor in mediating head and neck tumor growth, cell migration, and response to PI3K inhibitor

Introduction: Eph proteins have emerged as critical drivers affecting tumor growth and progression in human malignancies. Dysregulated expression of EphB3, a member of the Eph receptor gene family, has been reported in different cancers. However, the precise role of EphB3 in head and neck squamous cell carcinoma (HNSCC) has not been explored. In the current study, we examined the effect of EphB3 downregulation on HNSCC tumor cell growth, migration, and response to PIK3CA inhibition both in vitro and in an orthotopic model of head and neck cancer.

Materials and methods: Alterations in EPHB3 across cancer types in the TCGA database were accessed via cBioportal. shRNA approach was used to knockdown the levels of EphB3 in human and murine HNSCC cell lines. The effect of EphB3 knockdown on cell viability and cell migration was determined by MTT/Trypan blue assay and by Boyden chamber assay respectively. We also generated a BKM120 resistant HNSCC cell line to elucidate the functional role of EphB3 in mediating sensitivity to PI3K inhibitor. The phospho-EphB3 levels were analyzed by an immunoprecipitation assay. For in vivo testing, we used an orthotopic model of HNSCC. Immunohistochemistry and Western blot analysis was performed on cultured HNSCC cells and on tumor tissues to determine key proteins that are altered in response to EphB3 knockdown in the presence and absence of PI3K inhibition.

Results: Our TCGA data analysis showed that EphB3 is frequently co-amplified with PIK3CA in HNSCC. We therefore hypothesized that EphB3 amplification plays a pro-tumorigenic role in HNSCC and that EphB3 and PIK3CA are co-operating oncogenes that contribute toward its pathogenesis. This hypothesis was not experimentally supported since EphB3 knockdown failed to alter HNSCC tumor cell growth in vitro or in vivo with an orthotopic model. However, responsiveness of EphB3 knockdown tumors to the PI3K inhibitor, BKM120, was significantly decreased in terms of both tumor growth delay and survival. This is associated with an increase in pro-survival proteins, S6 and BcL-XL in the EphB3 shRNA tumors treated with BKM120 compared to controls. We further observed that EphB3 knockdown resulted in increased migration in vitro and increased EMT gene signature in vivo. To explain these results, we examined EphB3 phosphorylation levels in HNSCC at baseline. While total EphB3 levels were high, we found low phospho-EphB3 levels in HNSCCs. Forced EphB3 phosphorylation with an ephrin-B2-Fc fusion protein resulted in decreased HNSCC migration and cell growth and enhanced response to BKM120 in vitro.

Conclusions: Our data collectively indicate that progression of HNSCC selects for low/inhibited EphB3 activity to enhance their survival and migratory abilities and decrease response to PI3K inhibitor. Therefore, strategies focused on activating EphB3 might be helpful to inhibit tumor growth and enhance sensitivity to PI3K inhibitors in HNSCC.

Citation Format: Shilpa Bhatia, Anastacia Griego, Shelby Lennon, Ayman Oweida, Jaspreet Sharma, Christina Rohmer, Nomin Uyanga, Sanjana Bukkapatnam, Benjamin Van Court, David Raben, Christian Young, Lynn Heasley, Sana D. Karam. Role of EphB3 receptor in mediating head and neck tumor growth, cell migration, and response to PI3K inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2946.

Abstract 4169: Inhibition of EphB4-ephrin-B2 signaling results in enhanced sensitivity to cetuximab-radiation therapy in head and neck cancers

Introduction: The management of locally-advanced head and neck cancer patients relies on the combination treatment involving 7 weeks of radiation therapy (RT) with Cetuximab, an EGFR-inhibitor. Only a fraction of HNSCC patients, however, show response to cetuximab-radiation with an estimated 5-year overall survival of 46% compared to 36% with radiotherapy alone. This suggests potential involvement of redundant or compensatory tumor survival pathway that comes into action and blunts the therapeutic response. Based on our previous findings and published reports, elevated expression of EphB4, a member of Eph family of receptor tyrosine kinases and its membrane-bound ligand, ephrin-B2 might play a role in mediating this effect. In the current study, we hypothesized that EphB4-ephrin-B2 favors pro-tumorigenic survival signaling by altering the sensitivity to EGFR inhibitor and radiation. Therefore, combined inhibition of EphB4-ephrin-B2 signaling is critical to enhance sensitization of HNSCC towards anti-EGFR and radiation therapy.

Materials and methods: To test the underlying hypothesis, we used a blocking protein targeting EphB4-ephrin-B2 axis in the absence and presence of EGFR inhibitor with radiation in HNSCC cell lines and patient-derived xenograft (PDX) model. Alteration in the protein levels in control and treatment groups was detected by Western blotting and immunohistochemistry. Circulating levels of cytokines was analyzed in vivo by Mesoscale U-plex assay. Tumor tissues were subjected to human PhosphoRTK array to assess changes in the activation status of downstream targets of EphB4-ephrin-B2 signaling mediating response in the triple combination groups.

Results: Our data from locally advanced HNSCC patients treated with standard of care definitive Cetuximab-RT show high levels of both EphB4 and ephrin-B2 after failure of Cetuximab-RT. We observed significant tumor growth delay and increased response towards Cetuximab and radiation therapy following EphB4-ephrin-B2 inhibition resulting in better overall survival in PDX tumors and HNSCC cells. The tumor growth inhibition effects observed in vivo was accompanied by decrease in the levels of proliferation marker, angiogenic regulators, and increased apoptosis. Changes in levels of phopsho-receptor kinases and in circulating immune profile was also evident in tumors subjected to triple combination strategy.

Conclusions: Overall, our data suggest that EphB4-ephrin-B2 and EGFR pathway cross-talk with each other to circumvent the therapeutic response resulting in uncontrolled tumor growth, apoptotic evasion, and immune escape. Therefore, development of combinatorial approaches targeting Eph-ephrin family of proteins might show promising outcome to enhance sensitivity towards anti-EGFR therapeutics and radiation in head and neck cancers.

Citation Format: Shilpa Bhatia, Jaspreet Sharma, Sanjana Bukkapatnam, Ayman Oweida, Shelby Lennon, Parkash Gill, Antonio Jimeno, David Raben, Lynn Heasley, Sana D. Karam. Inhibition of EphB4-ephrin-B2 signaling results in enhanced sensitivity to cetuximab-radiation therapy in head and neck cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4169.

Inhibition of EphB4-Ephrin-B2 Signaling Enhances Response to Cetuximab-Radiation Therapy in Head and Neck Cancers

Purpose: The clinical success of targeted therapies such as cetuximab and radiotherapy (RT) is hampered by the low response rates and development of therapeutic resistance. In the current study, we investigated the involvement of EphB4-ephrin-B2 protumorigenic signaling in mediating resistance to EGFR inhibition and RT in head and neck cancers.Experimental Design: We used patient-derived xenograft (PDX) models of head and neck squamous cell carcinoma (HNSCC) and HNSCC cell lines to test our hypothesis. Tumor tissues were subjected to PhosphoRTK array, and Western blotting to detect changes in EphB4-ephrin-B2 targets. mRNA sequencing and microarray data analysis were performed on PDX tumors and HNSCC cell lines, respectively, to determine differences in gene expression of molecules involved in tumor cell growth, proliferation, and survival pathways. Effects on cell growth were determined by MTT assay on HNSCC cells downregulated for EphB4/ephrin-B2 expression, with and without EGFR inhibitor and radiation.Results: Our data from locally advanced HNSCC patients treated with standard-of-care definitive chemo-RT show elevated EphB4 and ephrin-B2 levels after failure of treatment. We observed significant response toward cetuximab and RT following EphB4-ephrin-B2 inhibition, resulting in improved survival in tumor-bearing mice. Tumor growth inhibition was accompanied by a decrease in the levels of proliferation and prosurvival molecules and increased apoptosis.Conclusions: Our findings underscore the importance of adopting rational drug combinations to enhance therapeutic effect. Our study documenting enhanced response of HNSCC to cetuximab-RT with EphB4-ephrin-B2 blockade has the potential to translate into the clinic to benefit this patient population. Clin Cancer Res; 24(18); 4539-50. ©2018 AACR.

Input vector optimization of feed-forward neural networks for fitting ab initio potential-energy databases

The variation in the fitting accuracy of neural networks (NNs) when used to fit databases comprising potential energies obtained from ab initio electronic structure calculations is investigated as a function of the number and nature of the elements employed in the input vector to the NN. Ab initio databases for H(2)O(2), HONO, Si(5), and H(2)C[Double Bond]CHBr were employed in the investigations. These systems were chosen so as to include four-, five-, and six-body systems containing first, second, third, and fourth row elements with a wide variety of chemical bonding and whose conformations cover a wide range of structures that occur under high-energy machining conditions and in chemical reactions involving cis-trans isomerizations, six different types of two-center bond ruptures, and two different three-center dissociation reactions. The ab initio databases for these systems were obtained using density functional theory/B3LYP, MP2, and MP4 methods with extended basis sets. A total of 31 input vectors were investigated. In each case, the elements of the input vector were chosen from interatomic distances, inverse powers of the interatomic distance, three-body angles, and dihedral angles. Both redundant and nonredundant input vectors were investigated. The results show that among all the input vectors investigated, the set employed in the Z-matrix specification of the molecular configurations in the electronic structure calculations gave the lowest NN fitting accuracy for both Si(5) and vinyl bromide. The underlying reason for this result appears to be the discontinuity present in the dihedral angle for planar geometries. The use of trigometric functions of the angles as input elements produced significantly improved fitting accuracy as this choice eliminates the discontinuity. The most accurate fitting was obtained when the elements of the input vector were taken to have the form R(ij) (-n), where the R(ij) are the interatomic distances. When the Levenberg-Marquardt procedure was modified to permit error minimization with respect to n as well as the weights and biases of the NN, the optimum powers were all found to lie in the range of 1.625-2.38 for the four systems studied. No statistically significant increase in fitting accuracy was achieved for vinyl bromide when a different value of n was employed and optimized for each bond type. The rate of change in the fitting error with n is found to be very small when n is near its optimum value. Consequently, good fitting accuracy can be achieved by employing a value of n in the middle of the above range. The use of interparticle distances as elements of the input vector rather than the Z-matrix variables employed in the electronic structure calculations is found to reduce the rms fitting errors by factors of 8.86 and 1.67 for Si(5) and vinyl bromide, respectively. If the interparticle distances are replaced with input elements of the form R(ij) (-n) with n optimized, further reductions in the rms error by a factor of 1.31 to 2.83 for the four systems investigated are obtained. A major advantage of using this procedure to increase NN fitting accuracy rather than increasing the number of neurons or the size of the database is that the required increase in computational effort is very small.

Development of generalized potential-energy surfaces using many-body expansions, neural networks, and moiety energy approximations

A general method for the development of potential-energy hypersurfaces is presented. The method combines a many-body expansion to represent the potential-energy surface with two-layer neural networks (NN) for each M-body term in the summations. The total number of NNs required is significantly reduced by employing a moiety energy approximation. An algorithm is presented that efficiently adjusts all the coupled NN parameters to the database for the surface. Application of the method to four different systems of increasing complexity shows that the fitting accuracy of the method is good to excellent. For some cases, it exceeds that available by other methods currently in literature. The method is illustrated by fitting large databases of ab initio energies for Si(n) (n=3,4,...,7) clusters obtained from density functional theory calculations and for vinyl bromide (C(2)H(3)Br) and all products for dissociation into six open reaction channels (12 if the reverse reactions are counted as separate open channels) that include C-H and C-Br bond scissions, three-center HBr dissociation, and three-center H(2) dissociation. The vinyl bromide database comprises the ab initio energies of 71 969 configurations computed at MP4(SDQ) level with a 6-31G(d,p) basis set for the carbon and hydrogen atoms and Huzinaga's (4333/433/4) basis set augmented with split outer s and p orbitals (43321/4321/4) and a polarization f orbital with an exponent of 0.5 for the bromine atom. It is found that an expansion truncated after the three-body terms is sufficient to fit the Si(5) system with a mean absolute testing set error of 5.693x10(-4) eV. Expansions truncated after the four-body terms for Si(n) (n=3,4,5) and Si(n) (n=3,4,...,7) provide fits whose mean absolute testing set errors are 0.0056 and 0.0212 eV, respectively. For vinyl bromide, a many-body expansion truncated after the four-body terms provides fitting accuracy with mean absolute testing set errors that range between 0.0782 and 0.0808 eV. These errors correspond to mean percent errors that fall in the range 0.98%-1.01%. Our best result using the present method truncated after the four-body summation with 16 NNs yields a testing set error that is 20.3% higher than that obtained using a 15-dimensional (15-140-1) NN to fit the vinyl bromide database. This appears to be the price of the added simplicity of the many-body expansion procedure.