Abstract 5647: Single cell, multiomic spatial phenotyping of immunotherapy responses in head and neck cancer

Background: Immune checkpoint inhibitors (ICI) have proven to be game-changing treatments for mucosal head and neck squamous cell cancer (HNSCC). Emerging successes with anti-PD-1/PD-L1 therapy have led to durable responses and prolonged survival in both human papillomavirus-positive (HPV+) and negative (HPV-) patients. There is now a need for predictive biomarkers to guide patient selection for highly targeted ICI therapies as currently available diagnostic biomarkers have a limited value. The tumor microenvironment (TME) composition, contexture, and cellular architecture are now recognized as key to understanding immune responsive and resistant phenotypes. Here, we are using a spatial biology approach to explore the TME in metastatic/recurrent HNSCC tumors treated with Pembrolizumab/Nivolumab.

Methods: In this study, we used single cell, multiomic spatial phenotyping utilizing the PhenoCycler-Fusion spatial biology platform to characterize the TME of HNSCC tumors from a cohort of n=40 patients. The discovery cohort consisted of patients who had complete vs. partial vs. stable vs. progressive responses to ICI therapy. We first analyzed tissues using an ultrahigh-plex antibody panel of >60 antibodies that label immune cell lineages, checkpoints, activation markers as well as tissue structure and the stroma. We then conducted whole-slide, single cell resolution RNA detection with complementary markers on serial sections from the same tissue blocks; the combination of these data allowed us to obtain multiomic spatial signatures that offered uniquely comprehensive insight into the TME of our tissue cohorts.

Results: Our study identified highly resolved tissue immune contexture analysis and metabolic tissue signatures associated with resistance and sensitivity to immunotherapy. Most notably, multiomic profiling of HNSCC tumours provided deeper insights into ICI therapy resistance than the single omics based approaches alone.

Conclusions: Our study demonstrates the power of unbiased, multiomic spatial phenotyping with whole-slide imaging to identify biomarkers associated with response to ICI therapy in HNSCC.

Citation Format: HaYeun Ji, Niyati Jhaveri, Ning Ma, Bassem B. Cheikh, Aditya Pratapa, James Monkman, Ken O’Byrne, Brett Hughes, Arutha Kulasinghe, Oliver Braubach. Single cell, multiomic spatial phenotyping of immunotherapy responses in head and neck cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5647.

Abstract 5648: Single cell spatial phenotyping of bladder tumors with a novel mechanism of NKG2A and HLA-E mediated resistance to BCG immunotherapy

Background: ~75% of diagnosed bladder tumors are non-muscle-invasive, requiring instillation of M. bovis Bacillus Calmette-Guérin (BCG) with recurrence rates observed in ~50% of patients. Treatments for BCG-resistant bladder tumors have lagged because few studies have tried to understand the relationship between timing of tumor recurrence and the state of immune system at the time of recurrence. Natural Killer (NK) cells are very early responders to tumor cells. HLA-E, like PD-L1, is sensitive to IFN-γ and strongly inhibits NKG2A+ NK and CD8 T cells and is commonly upregulated on tumors. We observed that BCG exposure results in chronic activation of NK and CD8 T cells and their acquisition of NKG2A and PD-1 phenotypes. Upon tumor recurrence in all patients sampled, a subset of the tumor cells aggregated in nests, were activated in response to NK/CD8 T cell-derived IFN-γ, and upregulate HLA-E and PD-L1. Spatial sequencing revealed HLA-EBright tumor nests with high levels of CXCL9/10/11 and in significantly closer proximity to NK/CD8 T cells (and Tregs) compared with HLA-EDim tumor nests that lacked CXCL9/10/11. Here, we apply single cell spatial phenotyping to study major subsets of NK cells in the TME of bladder tumors obtained from patient matched tumor sections before and after BCG therapy.

Purpose of the study: The goal of this study is to understand the underlying cell-to-cell interactions that promote BCG resistance in non-muscle-invasive bladder cancer (NMIBC).

Methods: The PhenoCycler technology centers around an oligo-based barcoding strategy, in which oligonucleotide-labeled antibodies are imaged in iterative cycles of hybridized/dehybridized complementary oligonucleotide fluorescent reporters. The platform enables (1) whole-slide imaging, (2) single-cell and subcellular resolution, (3) compatibility with a wide range of FFPE tissues, (4) customized content and plexing capability and (5) sophisticated analysis of cell phenotypes and cellular neighborhoods.

Results and conclusions: We developed a comprehensive antibody panel for in-depth analysis of the TME of bladder tumors. Our panel centers around a core of 67 markers for cell lineage, immune checkpoints, immune activation markers, tissue structure and vasculature. This core was supplemented with a module of additional antibodies that define complex NK cell phenotypes, including markers of maturation and differentiation, metabolism, activation and inhibition, trafficking, cytolytic killing, as well as cytokines/chemokines that shape the TME. The power of single cell spatial biology is the ability to visualize all major subsets of NK cells and their associated microenvironment simultaneously in single tissue sections. In doing so, we are defining novel functional interactions as new correlates of BCG resistance and identifying pathways that can be exploited for next-gen immunotherapies.

Citation Format: Dmytro Klymyshyn, Niyati Jhaveri, Nadine Nelson, Michael Prater, Zhenqin Wu, Steven Hamel, Matthew D. Galsky, Nina Bhardwaj, John P. Sfakianos, Subham Basu, Oliver Braubach, Amir Horowitz. Single cell spatial phenotyping of bladder tumors with a novel mechanism of NKG2A and HLA-E mediated resistance to BCG immunotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5648.

Abstract 5626: Multiomic spatial profiling of the tumor immune microenvironment at single cell resolution

Background: It has been well established that the tumor microenvironment (TME), which comprises cancer cells, stromal cells, and surrounding extracellular matrix, plays a critical role in cancer development, progression, and control. The immunological components within tumors, known as the tumor immune microenvironment (TiME), have also been implicated in tumor development, recurrence, and metastasis. Effective strategies for cancer immunotherapies will require a deep understanding of the factors that shape both the TME and TiME. Here, we describe a spatial multiomics approach that utilizes RNAscope™ ISH technology paired with high-plex whole-slide spatial phenotyping with the PhenoCycler™-Fusion platform. This two-step approach is compatible with human FFPE tissues and enables researchers to characterize the spatial biology of the TiME more accurately by detecting RNA and protein markers on serial sections. The resulting multiomic data more accurately reveal the interplay between TME and TiME by giving insight into cell lineages, surrounding structures, as well as secreted chemokines and cytokines that exist within the TME ecosystem.

Methods: We performed ultrahigh-plex spatial phenotyping on the PhenoCycler-Fusion on FFPE tumor tissue sections, using an antibody panel that is designed for immune cell phenotyping, evaluation of immune contexture and proliferation across the TME. Using serial sections from the same tissue blocks, we then ran the RNAscope HiPlex v2 assay automated on the PhenoCycler-Fusion system. This assay consisted of a 12-plex immuno-oncology panel of RNA target probes, which were selected to detect macrophages, chemokines, and cytokines within tumors. We used Phenoplex software to analyze the protein and RNA datasets and to compute cell phenotypes and spatial associations.

Results and Conclusions: In this proof-of-concept study, we demonstrate the utility of multiomic spatial profiling on the PhenoCycler-Fusion platform. Analysis of the resulting multiplex imaging data not only revealed the structural organization of cells within the TME, but also activation states of immune cells. Together, this information provides a more complete functional map of immune cells within the TME and TiME and thereby enriches our understanding of tumor biology that may be deterministic of immunotherapy responsiveness. This work paves the way for future research that will rely on deep spatial phenotyping with protein biomarkers coupled with accurate quantification of the expression of regulatory cytokines, chemokines, growth factors, or non-coding RNAs that only RNA probes can detect.

Citation Format: Niyati Jhaveri, HaYeun Ji, Anushka Dikshit, Jessica Yuan, Emerald Doolittle, Steve Zhou, Maithreyan Srinivasan, Bassem B. Cheikh, Fabian Schneider, James Mansfield, Julia Kennedy-Darling, Oliver Braubach. Multiomic spatial profiling of the tumor immune microenvironment at single cell resolution. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5626.

Compartmentalized spatial profiling of the tumor microenvironment in head and neck squamous cell carcinoma identifies immune checkpoint molecules and tumor necrosis factor receptor superfamily members as biomarkers of response to immunotherapy

Mucosal head and neck squamous cell carcinoma (HNSCC) are the seventh most common cancer, with approximately 50% of patients living beyond 5 years. Immune checkpoint inhibitors (ICIs) have shown promising results in patients with recurrent or metastatic (R/M) disease, however, only a subset of patients benefit from immunotherapy. Studies have implicated the tumor microenvironment (TME) of HNSCC as a major factor in therapy response, highlighting the need to better understand the TME, particularly by spatially resolved means to determine cellular and molecular components. Here, we employed targeted spatial profiling of proteins on a cohort of pre-treatment tissues from patients with R/M disease to identify novel biomarkers of response within the tumor and stromal margins. By grouping patient outcome categories into response or non-response, we show that immune checkpoint molecules, including PD-L1, B7-H3, and VISTA, were differentially expressed. Patient responders possessed significantly higher tumor expression of PD-L1 and B7-H3, but lower expression of VISTA. Analysis of response subgroups by Response Evaluation Criteria in Solid Tumors (RECIST) criteria indicated that tumor necrosis factor receptor (TNFR) superfamily members including OX40L, CD27, 4-1BB, CD40, and CD95/Fas, were associated with immunotherapy outcome. OX40L expression in tumor regions was higher in patient-responders than those with progressive disease (PD), while other TNFR members, CD27 and CD95/Fas were lower expressed in patients with a partial response (PR) compared to those with PD. Furthermore, we found that high 4-1BB expression in the tumor compartment, but not in the stroma, was associated with better overall survival (OS) (HR= 0.28, p-adjusted= 0.040). Moreover, high CD40 expression in tumor regions (HR= 0.27, p-adjusted= 0.035), and high CD27 expression in the stroma (HR= 0.2, p-adjusted=0.032) were associated with better survival outcomes. Taken together, this study supports the role of immune checkpoint molecules and implicates the TNFR superfamily as key players in immunotherapy response in our cohort of HNSCC. Validation of these findings in a prospective study is required to determine the robustness of these tissue signatures.

Abstract 3877: Deep ultrahigh-plex spatial phenotyping of human cancer tissues

Spatial phenotyping is poised to revolutionize cancer research and treatment. Technologies like CO-Detection by indEXing (CODEX), which enable the detection of dozens of protein biomarkers in situ, have already transformed immuno-oncology and are expected to play formative roles in future research. To further support the implementation of CODEX in cancer research, we present a comprehensive 100 antibody panel that is aimed at in-depth identification of immune cell lineages, activation states, immune checkpoints, tissue structure, cellular signaling, apoptosis, DNA damage and cellular metabolism. Deployment of this panel is possible at high-throughput on the CODEX platform, which is a fully-integrated spatial biology solution that provides cyclical multiplexed imaging at unprecedented resolution and rapid turn-around time. The key features of this novel spatial biology system include: 1) true single-cell and sub-cellular resolution, 2) unparalleled biomarker imaging depth on whole FFPE samples, 3) wide-ranging compatibility with whole slide FFPE tissues, 4) panel customization and flexibility via dedicated barcodes, 5) uncompromised access to whole tissues, and 6) sophisticated single-cell analytical metrics. In this study, we generate a comprehensive account of the spatial biology in different tumor tissues including lung cancer, colon cancer, and melanoma using the CODEX instrument. Single-cell spatial phenotyping coupled with deep bioinformatic analyses reveals new quantitative phenotypic and spatial information that will be essential to gain further insights into distinct cellular neighborhoods and their role in regulating immune and metabolic functions of certain cancers.

Citation Format: Niyati Jhaveri, Nadya Nikulina, Hailing Zong, Ning Ma, Bassem Ben Cheikh, Aditya Pratapa, Yasmin Kassim, Bhaskar Anand, Michael Prater, Subham Basu, Oliver Braubach. Deep ultrahigh-plex spatial phenotyping of human cancer tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3877.

DDRE-06. REGULATION OF TUMOR MICROENVIRONMENT VIA ENDOTHELIAL-TO-MESENCHYMAL TRANSITION BLOCKADE IN GLIOBLASTOMA-ASSOCIATED BRAIN ENDOTHELIAL CELLS

Glioblastoma multiforme (GBM) is a malignant brain tumor noted for its extensive vascularity, aggressiveness, and highly invasive nature. Glioma stem cells (GSC) are a subpopulation of cells resistant to treatments and considered responsible for tumor recurrence. GSC are found in the vascular niches of the tumors, where endothelial cells (EC) secrete factors that stimulate GSC self-renewal. There are several studies regarding the effects of the vasculature on CSC and tumorigenesis, but little is known about how GSC affects the vasculature. Resistance to therapies and tumor recurrence greatly rely on the pro-angiogenic nature and aberrant vasculature of GBM. The endothelial-to-mesenchymal transition (EndMT) supports the pro-angiogenic and invasive characteristics of GBM. Hence, blocking the EndMT would be a promising approach to inhibit tumor progression and recurrence. We have examined the dynamic cross-talk between GSC and EC during EndMT. We demonstrate that GSC induce EndMT in brain endothelial cells (BEC), through a collaboration between TGF-β and Notch pathways, nicotinamide N-methyltransferase upregulation and other key signaling routes. Elucidating the cells and molecular pathways responsible for this process represents a milestone in the understanding of the tumor microenvironment and will help develop novel treatments in glioma therapy. One promising treatment, developed by our research group, is the conjugate of temozolomide and perillyl alcohol (POH), NEO212. This drug blocks EndMT induction in BEC and reverts the mesenchymal phenotype of tumor-associated BEC (TuBEC), reducing the invasiveness and pro-angiogenic properties of GBM in vitro and in vivo. We are currently performing Investigational New Drug (IND)-enabling studies, and we foresee that NEO212 will be of great clinical value for the treatment of GBM.

Abstract A65: Spatial characterization of drug resistance in ovarian cancer

As we strive to prolong patient survival, the advent of targeted therapy for the treatment of ovarian cancer has significantly added to our armamentarium. Unfortunately, both chemotherapy and molecularly targeted PARPi approaches share the overarching limitation of the emergence of drug resistance. One key aspect towards realizing the potential of targeted therapies is a better understanding of the intrinsic and acquired resistance mechanisms that limit their efficacy. Through comprehensive genomic analysis of post-treatment patient samples, we recently identified the most common mechanism of acquired drug resistance in high-grade serous ovarian cancer (HGSC) to date, a transcriptional fusion involving ABCB1. ABCB1 encodes P-gp also known as multidrug resistance protein 1 (MDR1), a multi-transmembrane domain protein that is a member of the superfamily of ATP binding cassette (ABC) transporters involved in the cellular efflux of chemotherapeutic drugs. The SLC25A40-ABCB1 fusion was associated with upregulation of ABCB1 expression, whilst leaving the predicted ABCB1 protein unaltered. Interestingly, fusion events were only detected in patients who had been exposed to chemotherapies that are known substrates of P-gp, with the probability of fusion events closely correlated to the number of lines of P-gp substrate chemotherapy. Surprisingly, WGS analysis of patient samples revealed that not all tumor cells in fusion-positive patients carry the fusion. An intriguing possibility is that resistance within tumor sites is spatially ordered rather than random. Identifying such patterning could explain why tumor eradication has not been effective for the majority of HGSC patients to date. To address the subclonal localization and spatial patterning of ABCB1 fusions in HGSC, CASCADE (rapid autopsy program), biopsy specimens, and PDX tissue are being prescreened (qRT-PCR) to identify those with the highest levels of ABCB1 expression and thus most likely to harbor fusions. In situ DNA and RNA detection assays are being employed to identify ABCB1 fusions. To examine whether fusion negative cells also overexpress P-gp, IHC analysis will then be conducted to co-register fusion positivity and protein expression. We have successfully identified fusion events using ACD BaseScope technology and examined the localization of key HGSC genes including CCNE1 and ABCB1 through PCR FISH assays. In summary, this study will decipher the diversity of resistance mechanisms within individual HGSC patients, thereby providing critical information required for next-generation chemotherapy and PARPi clinical trials aimed at reversing or bypassing acquired resistance.

Citation Format: Kathleen I. Pishas, Elizabeth L. Christie, Jessica A. Beach, Kathryn Alsop, Alison Freimund, Nidhi Vashistha, Niyati Jhaveri, Emerald Doolittle, Wei Wei, Bingqing Zhang, Xiao-Jun Ma, David D.L. Bowtell. Spatial characterization of drug resistance in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A65.

Abstract 2802: In situ detection of PD-1+CXCL13+CD8+ T cells in non-small cell lung cancer

Recent reports identified one subset of intratumoral CD8+ cytotoxic T lymphocytes (CTLs) in non-small cell lung cancer (NSCLC) that are PD-1high with distinct molecular and functional properties. Strikingly, these cells produce very high levels of CXCL13 mRNA and protein, which may mediate immune recruitment. Furthermore, the presence of PD-1high CD8+ T lymphocytes are strongly predictive for both response and survival in NSCLC patients treated with PD-1 blockade. Thus, it is of great value to develop a practical biomarker assay to specifically detect these cells in formalin-fixed paraffin-embedded (FFPE) tumor biopsies. In this study, we combined the highly sensitive and specific RNAscope multiplex fluorescent RNA in situ hybridization (ISH) assay detecting CXCL13 and PDCD1 mRNAs with immunohistochemistry (IHC) detecting CD8 protein in a single tissue section to directly visualize PD-1+CXCL13+CD8+ T lymphocytes in NSCLC tissues. Two NSCLC tissue microarrays (TMAs) consisting of 63 independent patient FFPE samples were stained with full automation using the Leica BOND RX instrument. The resulting slides were scanned, and the images were analyzed using the Perkin Elmer Phenochart software. 57 of the 63 TMA cores were available for image analysis. Each tissue core was first examined under 4X magnification, then snapshot images of three independent 40X fields with enriched CD8+ cells (if present) were taken. CD8+ cells, CXCL13+ cells, and PD-1+ cells in each snapshot were counted. Every snapshot contained both stromal and tumor regions. 43 samples contained high (>20) CD8+ CTLs whereas 14 samples contained low (≤20) CD8+ CTLs across the three snapshots. Interestingly, PD-1+CXCL13+CD8+ cells were detected in both high and low CTL tumors. Five of 57 tumors carried high percentages of PD-1+CXCL13+CD8+ cells (>10% of CD8+ CTLs), with three from high CTL tumors and two from low CTL tumors. These results demonstrate that this fully automated multiplexed RNAscope dual ISH/IHC assay allows for co-localization of RNA and protein biomarkers in single cells with morphological context. The ability to detect RNA and protein in a single slide-based assay enables immune profiling applications to include biomarkers such as secreted proteins and non-coding RNAs that are difficult or impossible to detect by IHC.

Citation Format: Na Li, Bingqing Zhang, Niyati Jhaveri, Zhifu Zhang, Xin Wang, Hongzhe Sun, Ying Zhou, Courtney Anderson, Xiao-Jun Ma. In situ detection of PD-1+CXCL13+CD8+ T cells in non-small cell lung cancer [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 2802.

NEO212, a conjugate of temozolomide and perillyl alcohol, blocks the endothelial-to-mesenchymal transition in tumor-associated brain endothelial cells in glioblastoma

As the endothelial-to-mesenchymal transition (EndMT) supports the pro-angiogenic and invasive characteristics of glioblastoma multiforme (GBM), blocking this process would be a promising approach to inhibit tumor progression and recurrence. Here, we demonstrate that glioma stem cells (GSC) induce EndMT in brain endothelial cells (BEC). TGF-β signaling is necessary, but not sufficient to induce this EndMT process. Cell-to-cell contact and the contribution of Notch signaling are also required. NEO212, a conjugate of temozolomide and perillyl alcohol, blocks EndMT induction and reverts the mesenchymal phenotype of tumor-associated BEC (TuBEC) by blocking TGF-β and Notch pathways. Consequently, NEO212 reduces the invasiveness and pro-angiogenic properties associated with TuBEC, without affecting control BEC. Intracranial co-implantation of BEC and GSC in athymic mice showed that EndMT occurs in vivo, and can be blocked by NEO212, supporting the potential clinical value of NEO212 for the treatment of GBM.

A novel drug conjugate, NEO212, targeting proneural and mesenchymal subtypes of patient-derived glioma cancer stem cells

Glioblastoma multiforme (GBM), a highly malignant brain tumor, accounts for half of all gliomas. Despite surgery, radiation and chemotherapy, the median survival is between 12 and 15 months. The poor prognosis is due to tumor recurrence attributed to chemoresistant glioma cancer stem cells (GSCs). Here we examined the effects of a novel compound NEO212, which is composed of two covalently conjugated anti-cancer compounds - temozolomide (TMZ) and perillyl alcohol (POH), on GSCs expressing either the proneural or mesenchymal gene signatures. These GSCs were obtained from patient-derived tumor tissue. Our findings demonstrate that NEO212 is 10 fold more cytotoxic to GSCs than TMZ (standard-of-care). Furthermore, NEO212 is effective against both proneural and clinically aggressive mesenchymal GSC subtypes. The mechanism of NEO212 mediated-cytotoxicity is through double-strand DNA breaks and apoptosis. In vivo studies show that NEO212 significantly delays tumor growth of both proneural and mesenchymal tumor stem cell populations. Patient-derived GSCs and tumors derived from these cells are highly reflective of the heterogeneity in human GBM. The efficacy of NEO212 against both GSC subtypes indicates that NEO212 has great clinical potential to effectively target GBM.

Effects of convection-enhanced delivery of bevacizumab on survival of glioma-bearing animals

OBJECT

Bevacizumab (Avastin), an antibody to vascular endothelial growth factor (VEGF), alone or in combination with irinotecan (Camptosar [CPT-11]), is a promising treatment for recurrent glioblastoma. However, the intravenous (IV) administration of bevacizumab produces a number of systemic side effects, and the increase in survival it provides for patients with recurrent glioblastoma is still only a few months. Because bevacizumab is an antibody against VEGF, which is secreted into the extracellular milieu by glioma cells, the authors hypothesized that direct chronic intratumoral delivery techniques (i.e., convection-enhanced delivery [CED]) can be more effective than IV administration. To test this hypothesis, the authors compared outcomes for these routes of bevacizumab application with respect to animal survival, microvessel density (MVD), and inflammatory cell distribution.

METHODS

Two human glioma cell lines, U87 and U251, were used as sources of intracranial tumor cells. The glioma cell lines were implanted into the brains of mice in an orthotopic xenograft mouse tumor model. After 7 days, the mice were treated with one of the following: 1) vehicle, 2) CED bevacizumab, 3) IV bevacizumab, 4) intraperitoneal (IP) irinotecan, 5) CED bevacizumab plus IP irinotecan, or 6) IV bevacizumab plus IP irinotecan. Alzet micro-osmotic pumps were used to introduce bevacizumab directly into the tumor. Survival was monitored. Excised tumor tissue samples were immunostained to measure MVD and inflammatory cell and growth factor levels.

RESULTS

The results demonstrate that mice treated with CED of bevacizumab alone or in combination with irinotecan survived longer than those treated systemically; CED-treated animals survived 30% longer than IV-treated animals. In combination studies, CED bevacizumab plus CPT-11 increased survival by more than 90%, whereas IV bevacizumab plus CPT-11 increased survival by 40%. Furthermore, CED bevacizumab-treated tissues exhibited decreased MVD compared with that of IV-treated tissues. In additional studies, the infiltration of macrophages and dendritic cells into CED-treated animals were increased compared with those in IV-treated animals, suggesting a highly active inflammatory response taking place in CED-treated mice.

CONCLUSIONS

The administration of bevacizumab via CED increases survival over that of treatment with IV bevacizumab. Thus, CED of bevacizumab alone or in combination with chemotherapy can be an effective protocol for treating gliomas.

Tumor vasculature and glioma stem cells: Contributions to glioma progression

Glioblastoma multiforme (GBM), the most malignant of brain tumors, is characterized by extensive vascularization and a high degree of invasion. The current standard of care is not very effective, resulting in tumor recurrence with patients rarely surviving over 2 years. This tumor recurrence is attributed to the presence of chemo and radiation resistant glioma stem cells (GSCs). These cells are associated with vascular niches which regulate GSC self-renewal and survival. Recent studies suggest that while blood vessels support glioma stem cells, these tumor cells in turn may regulate and contribute to the tumor vasculature by transdifferentiating into endothelial cells directly or through the secretion of regulatory growth factors such as vascular endothelial growth factor (VEGF) and hepatoma derived growth factor (HDGF). The relationship between the tumor vasculature and the glioma stem cells is the subject of this review.

Sequential administration of carbon nanotubes and near-infrared radiation for the treatment of gliomas

The objective was to use carbon nanotubes (CNT) coupled with near-infrared radiation (NIR) to induce hyperthermia as a novel non-ionizing radiation treatment for primary brain tumors, glioblastoma multiforme (GBM). In this study, we report the therapeutic potential of hyperthermia-induced thermal ablation using the sequential administration of carbon nanotubes (CNT) and NIR. In vitro studies were performed using glioma tumor cell lines (U251, U87, LN229, T98G). Glioma cells were incubated with CNTs for 24 h followed by exposure to NIR for 10 min. Glioma cells preferentially internalized CNTs, which upon NIR exposure, generated heat, causing necrotic cell death. There were minimal effects to normal cells, which correlate to their minimal uptake of CNTs. Furthermore, this protocol caused cell death to glioma cancer stem cells, and drug-resistant as well as drug-sensitive glioma cells. This sequential hyperthermia therapy was effective in vivo in the rodent tumor model resulting in tumor shrinkage and no recurrence after only one treatment. In conclusion, this sequence of selective CNT administration followed by NIR activation provides a new approach to the treatment of glioma, particularly drug-resistant gliomas.

Abstract 3740: Temozolomide-perillyl alcohol conjugate is cytotoxic for glioma cancer stem cells

Glioblastoma multiforme (GBM), the most malignant glioma, is a highly invasive tumor which is usually fatal within 2 years. The chemotherapeutic agent of choice is temozolomide (TMZ); however glioma patients inevitably become resistant to TMZ and tumors recur. Tumor recurrence has been associated with highly invasive, chemoresistant cancer stem cells (CSC) which is resistant to TMZ. We have constructed a new chemical entity by conjugating TMZ to perillyl alcohol (POH) via a carbamate bond. This compound, TMZ-POH, contains POH, a naturally occurring monoterpene that reduces tumor cell migration and has anti-tumor properties against gliomas as well as other cancers. In the studies presented here we demonstrate that TMZ-POH is cytotoxic to CSCs without affecting normal stem cells. The mechanism of TMZ-POH induced cytotoxicity is mediated in part through the DNA damage response pathway and apoptosis. Furthermore, the TMZ-POH conjugate is 5 to 10 fold more effective in inducing cell death compared to TMZ, POH or the mixture of these agents. Our data show that TMZ-POH is a promising novel compound directed against cancer stem cells and therefore important for the treatment of drug resistant, recurrent gliomas.

Citation Format: Niyati Jhaveri, Fabienne Agasse, Florence M. Hofman, Thomas C. Chen. Temozolomide-perillyl alcohol conjugate is cytotoxic for glioma cancer stem cells. [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 3740. doi:10.1158/1538-7445.AM2013-3740

Abstract C74: Temozolomide-perillyl alcohol conjugate is cytotoxic for glioma cancer stem cells

Glioblastoma multiforme (GBM), the most malignant glioma, is a highly invasive tumor which is usually fatal within 2 years. The chemotherapeutic agent of choice is temozolomide (TMZ); however glioma patients inevitably become resistant to TMZ and tumors recur. Tumor recurrence has been associated with highly invasive, chemoresistant cancer stem cells (CSC) which is resistant to TMZ. We have constructed a new chemical entity by conjugating TMZ to perillyl alcohol (POH) via a carbamate bond. This compound, TMZ-POH, contains POH, a naturally occurring monoterpene that reduces tumor cell migration and has anti-tumor properties against gliomas as well as other cancers. In the studies presented here we demonstrate that TMZ-POH is cytotoxic to CSCs without affecting normal stem cells. The mechanism of TMZ-POH induced cytotoxicity is mediated in part through the DNA damage response pathway and apoptosis. Furthermore, the TMZ-POH conjugate is 5 to 10 fold more effective in inducing cell death compared to TMZ, POH or the mixture of these agents. Our data show that TMZ-POH is a promising novel compound directed against cancer stem cells and therefore important for the treatment of drug resistant, recurrent gliomas.

Citation Format: Niyati Jhaveri, Fabienne Agasse, Florence M. Hofman, Thomas C. Chen. Temozolomide-perillyl alcohol conjugate is cytotoxic for glioma cancer stem cells. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C74.

Perillyl alcohol for the treatment of temozolomide-resistant gliomas

Perillyl alcohol (POH) is a monoterpene that has been used orally for the treatment of systemic cancer. However, when used orally significant gastrointestinal side effects and lack of overall efficacy were documented. Recently, in a phase II trial in Brazil for the treatment of temozolomide (TMZ)-resistant malignant gliomas, POH was well tolerated when administered intranasally. The present study explores the effects and mechanisms of POH on TMZ-sensitive and TMZ-resistant glioma cells. In vitro studies showed that POH was cytotoxic to TMZ-resistant as well as TMZ-sensitive glioma cells, and this effect was independent of O(6)-methylguanine-DNA methyltransferase expression. POH induced cytotoxicity, in part, through the endoplasmic reticulum (ER) stress pathway as shown by the increased expression of glucose-regulated protein-78 (GRP78), activating transcription factor 3, and C/EBP-homologous protein. In addition, POH impeded survival pathways, such as mTOR and Ras. As well, POH reduced the invasive capacity of sensitive and resistant glioma cells. POH alone and/or in combination with other ER stress-inducing cytotoxic drugs (i.e., 2, 5-dimethyl-celecoxib, nelfinavir) further induced apoptosis in TMZ-sensitive and TMZ-resistant glioma cells. To show whether intranasal delivery of POH was effective for the treatment of TMZ-resistant gliomas, animals bearing intracranial tumors were given POH intranasally. Animals treated through intranasal administration of POH exhibited a decrease in tumor growth and an increase in survival. Our data show that POH is an effective anti-glioma cytotoxic agent for TMZ-resistant gliomas when administered intranasally.

A critical role for GRP78/BiP in the tumor microenvironment for neovascularization during tumor growth and metastasis

Glucose-regulated protein 78 (GRP78)/BiP is a multifunctional protein which plays a major role in endoplasmic reticulum (ER) protein processing, protein quality control, maintaining ER homeostasis, and controlling cell signaling and viability. Previously, using a transgene-induced mammary tumor model, we showed that Grp78 heterozygosity impeded cancer growth through suppression of tumor cell proliferation and promotion of apoptosis and the Grp78(+/-) mice exhibited dramatic reduction (70%) in the microvessel density (MVD) of the endogenous mammary tumors, while having no effect on the MVD of normal organs. This observation suggests that GRP78 may critically regulate the function of the host vasculature within the tumor microenvironment. In this article, we interrogated the role of GRP78 in the tumor microenvironment. In mouse tumor models in which wild-type (WT), syngeneic mammary tumor cells were injected into the host, we showed that Grp78(+/-) mice suppressed tumor growth and angiogenesis during the early phase but not during the late phase of tumor growth. Growth of metastatic lesions of WT, syngeneic melanoma cells in the Grp78(+/-) mice was potently suppressed. We created conditional heterozygous knockout of GRP78 in the host endothelial cells and showed severe reduction of tumor angiogenesis and metastatic growth, with minimal effect on normal tissue MVD. Furthermore, knockdown of GRP78 expression in immortalized human endothelial cells showed that GRP78 is a critical mediator of angiogenesis by regulating cell proliferation, survival, and migration. Our findings suggest that concomitant use of current chemotherapeutic agents and novel therapies against GRP78 may offer a powerful dual approach to arrest cancer initiation, progression, and metastasis.