Efficacy, safety, and biomarker analyses of bintrafusp alfa, a bifunctional fusion protein targeting TGF-β and PD-L1, in patients with advanced non-small cell lung cancer

BACKGROUND

Bintrafusp alfa, a first-in-class bifunctional fusion protein targeting transforming growth factor-β (TGF-β) and programmed cell death ligand 1, has demonstrated encouraging efficacy as second-line treatment in patients with non-small cell lung cancer (NSCLC) in a dose expansion cohort of the phase 1, open-label clinical trial (NCT02517398). Here, we report the safety, efficacy, and biomarker analysis of bintrafusp alfa in a second expansion cohort of the same trial (biomarker cohort).

METHODS

Patients with stage IIIb/IV NSCLC who were either immune checkpoint inhibitor (ICI)-naïve (n=18) or ICI-experienced (n=23) were enrolled. The primary endpoint was the best overall response. Paired biopsies (n=9/41) and peripheral blood (n=14/41) pretreatment and on-treatment were studied to determine the immunological effects of treatment and for associations with clinical activity.

RESULTS

Per independent review committee assessment, objective responses were observed in the ICI-naïve group (overall response rate, 27.8%). No new or unexpected safety signals were identified. Circulating TGF-β levels were reduced (>97%; p<0.001) 2 weeks after initiation of treatment with bintrafusp alfa and remained reduced up to 12 weeks. Increases in lymphocytes and tumor-associated macrophages (TAMs) were observed in on-treatment biospies, with an increase in the M2 (tumor trophic TAMs)/M1 (inflammatory TAMs) ratio associated with poor outcomes. Specific peripheral immune analytes at baseline and early changes after treatment were associated with clinical response.

CONCLUSIONS

Bintrafusp alfa was observed to have modest clinical activity and manageable safety, and was associated with notable immunologic changes involving modulation of the tumor immune microenvironment in patients with advanced NSCLC.

Prediction of cancer treatment response from histopathology images through imputed transcriptomics

Advances in artificial intelligence have paved the way for leveraging hematoxylin and eosin (H&E)-stained tumor slides for precision oncology. We present ENLIGHT-DeepPT, an approach for predicting response to multiple targeted and immunotherapies from H&E-slides. In difference from existing approaches that aim to predict treatment response directly from the slides, ENLIGHT-DeepPT is an indirect two-step approach consisting of (1) DeepPT, a new deep-learning framework that predicts genome-wide tumor mRNA expression from slides, and (2) ENLIGHT, which predicts response based on the DeepPT inferred expression values. DeepPT successfully predicts transcriptomics in all 16 TCGA cohorts tested and generalizes well to two independent datasets. Our key contribution is showing that ENLIGHT-DeepPT successfully predicts true responders in five independent patients' cohorts involving four different treatments spanning six cancer types with an overall odds ratio of 2.44, increasing the baseline response rate by 43.47% among predicted responders, without the need for any treatment data for training. Furthermore, its prediction accuracy on these datasets is comparable to a supervised approach predicting the response directly from the images, which needs to be trained and tested on the same cohort. ENLIGHT-DeepPT future application could provide clinicians with rapid treatment recommendations to an array of different therapies and importantly, may contribute to advancing precision oncology in developing countries.

GNRH2 Polymorphism in Men With Prostate Cancer Treated With Androgen Deprivation Therapy

BACKGROUND/AIM

Gonadotropin-releasing hormone 2 (GNRH2) is a poorly-studied peptide hormone that is widely distributed in the central nervous system and expressed in peripheral tissues of mammals. The non-synonymous rs6051545 variant in GNRH2 (A16V) has been linked to higher serum testosterone concentrations. This study investigated whether the A16V variant is associated with altered androgen-deprivation therapy (ADT) progression-free survival (PFS) and overall survival (OS).

PATIENTS AND METHODS

We examined the expression of GNRH2 in prostate tissue microarrays comprising normal tissue, prostatic hyperplasia, and prostate cancer using immunofluorescence. We also evaluated the GNRH2 genotype in 131 patients with prostate cancer who received ADT and compared PFS and OS between the variant and wild-type genotypes.

RESULTS

GNRH2 was detected in all prostate tissues, although expression did not vary with Gleason grade or disease stage (p=0.71). The GNRH2 A16V genotype was not associated with PFS or OS; however, univariate and multivariate analyses revealed Gleason score and definitive local therapy were each associated with PFS (p≤0.0074), whereas age and Gleason score were associated with OS (p≤0.0046).

CONCLUSION

GNRH2 is expressed in normal, hyperplastic, and neoplastic prostate tissues; the A16V variant is not related to treatment outcome or survival.

Abstract 4706: Multispectral immunofluorescence analysis of the olfactory neuroblastoma tumor immune microenvironment reveals macrophage and polymorphonuclear leukocyte stroma localization and tumor parenchyma exclusion

Background: Olfactory neuroblastoma (ONB), also known as esthesioneuroblastoma, is a rare malignancy of the nasal cavity and anterior skull base. Multispectral immunofluorescence (mxIF), allows for comprehensive evaluation of tumor immune cell spatial relationships and thorough characterization of the tumor immune microenvironment (TIME). The objective of this study was to comprehensively define the ONB myeloid cell TIME with mxIF.

Methods: A tissue microarray including 47 clinically annotated human ONB samples was obtained, in addition to IRB approval, from our tertiary care hospital. A myeloid specific panel was validated in ONB tissue as well as controls. The panel stained for CD15, CD68, CD11b, CD14, HLA-DR, synaptophysin, and DAPI. Phenotypes of interest included CD11b+/CD15+/CD14−/HLA-DRlow/− polymorphonuclear leukocytes (PMNs), CD11b+/CD14+/CD15−/HLA-DR low/−monocytes, and CD68+ Pan Macrophages. HALO image analysis v3.4 was used to objectively quantify immune cell spatial relationships. A retrospective chart review was performed from these clinically annotated specimens with collection of patient demographics, stage, Hyams grade, dural infiltration status, and outcomes.

Results: Three samples were excluded based on too little available tissue for meaningful analysis. Of the remaining 44, 38 were primary and 6 were recurrent tumors. PMNs, monocytes, and macrophages are present in the TIME of ONB at 22 cells per mm2, 2.0 cells per mm2, and 34 cells per mm2 respectively. Increased PMN and macrophage cell densities were noted in the stroma when compared to the tumor parenchyma (28 cells per mm2 vs 14 cells per mm2, p&lt;0.0001 and 46 cells per mm2 vs 21 cells per mm2, p&lt;0.0001). A similar trend was seen in monocytes (3.5 cells per mm2 vs 0.80 cells per mm2, p=0.0588) but it did not reach statistical significance. When we compared by Kadish Stage, higher stage (C/D) had more tumor infiltrating PMNs than low stage (A/B) (median of 1.3 cells per mm2 vs median 0 cells per mm2, p=0.0011). No further differences in cell distributions were noted when comparing for Hyams grade, stage, dural infiltration, recurrent disease, or other clinical factors. Nearest neighbor analysis demonstrates that macrophages are closer to tumor cells than PMNs or monocytes (19.68 µm vs 27.78 µm, p&lt;0.0001, and 25.77 µm, p=0.0026, respectively).

Conclusion: This study is the first to comprehensively define the ONB myeloid TIME using mxIF. Our study demonstrates the ONB TIME contains abundant myeloid populations. As these cells have been shown to be immunosuppressive, thereby fostering tumor cell escape and host evasion, in other human malignancies we posit they play a similar role in ONB. The functional study of myeloid populations in ONB, and whether they represent targets for therapeutic intervention, is warranted.

Citation Format: Riley Larkin, Diana Lopez, Yvette Robbins, Wiem Lassoued, Gary Gallia, Clint T. Allen, Nyall R. London. Multispectral immunofluorescence analysis of the olfactory neuroblastoma tumor immune microenvironment reveals macrophage and polymorphonuclear leukocyte stroma localization and tumor parenchyma exclusion. [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 4706.

Tumor cell HLA class I expression and pathologic response following neoadjuvant immunotherapy for newly diagnosed head and neck cancer

OBJECTIVES

Biomarkers are needed to identify patients likely to respond to neoadjuvant immunotherapy (NIT) prior to receiving definitive treatment.

MATERIALS AND METHODS

We hypothesized that expression of tumor cell HLA class I would correlate with pathologic response (PR) following NIT for primary untreated head and neck cancer. Multispectral immunofluorescence of pre- and post-treatment biopsy specimens from a neoadjuvant study of bintrafusp alfa, a dual TGF-β and PD-L1 inhibitor, was performed.

RESULTS

Discordant expression of tumor cell HLA class I and PD-L1 measured by multispectral immunofluorescence was observed with most positive tumor cells expressing HLA class I or PD-L1 but not both. Spatial analysis revealed colocalization between tumor parenchyma T cells and HLA class I positive tumors cells, but no clear colocalization between T cells and PD-L1 positive tumor cells. Greater pre-treatment tumor cell HLA class I expression, but not PD-L1 expression or tumor T cell infiltration, correlated with the development of a PR. Additionally, increased tumor cell HLA class I expression after NIT compared to before NIT correlated with development of a PR, whereas inconsistent changes in PD-L1 and T cell infiltration were observed after treatment in all patients.

CONCLUSIONS

These data provide the rationale for the study of tumor cell HLA class I expression in larger prospective studies powered to determine the performance of biomarkers of PR in newly diagnosed HNSCC patients receiving NIT.

Multi-spectral immunofluorescence evaluation of the myeloid, T cell, and natural killer cell tumor immune microenvironment in chordoma may guide immunotherapeutic strategies

Background

Chordoma is a rare, invasive, and devastating bone malignancy of residual notochord tissue that arises at the skull base, sacrum, or spine. In order to maximize immunotherapeutic approaches as a potential treatment strategy in chordoma it is important to fully characterize the tumor immune microenvironment (TIME). Multispectral immunofluorescence (MIF) allows for comprehensive evaluation of tumor compartments, molecular co-expression, and immune cell spatial relationships. Here we implement MIF to define the myeloid, T cell, and natural killer (NK) cell compartments in an effort to guide rational design of immunotherapeutic strategies for chordoma.

Methods

Chordoma tumor tissue from 57 patients was evaluated using MIF. Three panels were validated to assess myeloid cell, T cell, and NK cell populations. Slides were stained using an automated system and HALO software objective analysis was utilized for quantitative immune cell density and spatial comparisons between tumor and stroma compartments.

Results

Chordoma TIME analysis revealed macrophage infiltration of the tumor parenchyma at a significantly higher density than stroma. In contrast, helper T cells, cytotoxic T cells, and T regulatory cells were significantly more abundant in stroma versus tumor. T cell compartment infiltration more commonly demonstrated a tumor parenchymal exclusion pattern, most markedly among cytotoxic T cells. NK cells were sparsely found within the chordoma TIME and few were in an activated state. No immune composition differences were seen in chordomas originating from diverse anatomic sites or between those resected at primary versus advanced disease stage.

Conclusion

This is the first comprehensive evaluation of the chordoma TIME including myeloid, T cell, and NK cell appraisal using MIF. Our findings demonstrate that myeloid cells significantly infiltrate chordoma tumor parenchyma while T cells tend to be tumor parenchymal excluded with high stromal infiltration. On average, myeloid cells are found nearer to target tumor cells than T cells, potentially resulting in restriction of T effector cell function. This study suggests that future immunotherapy combinations for chordoma should be aimed at decreasing myeloid cell suppressive function while enhancing cytotoxic T cell and NK cell killing.

Enhanced neoepitope-specific immunity following neoadjuvant PD-L1 and TGF-b blockade in HPV-unrelated head and neck cancer

BACKGROUND

Head and neck squamous cell carcinoma not associated with human papillomavirus (HPV-unrelated HNSCC) is associated with high rates of recurrence and poor survival.

METHODS

We conducted a clinical trial in 14 patients with newly diagnosed, HPV-unrelated HNSCC to evaluate the safety and efficacy of neoadjuvant bintrafusp alfa, a bifunctional fusion protein that blocks programmed death-ligand 1 (PD-L1) and neutralizes transforming growth factor-beta (TGF-).

RESULTS

Bintrafusp alfa was well tolerated, and no treatment-associated surgical delays or complications occurred. Objective pathologic responses were observed and 12 of 14 patients (86%) were alive and disease free at one year. Alterations in regulatory T cell infiltration and spatial distribution relative to proliferating CD8 T cells indicated reversal of Treg immunosuppression in the primary tumor. Detection of neoepitope-specific tumor T cell responses, but not viral-specific responses, correlated with development of a pathologic response. Detection of neoepitope-specific responses and pathologic responses in tumors was not correlated with genomic features or tumor antigenicity but was associated with reduced pre-treatment myeloid cell tumor infiltration. These results indicate that dual PD-L1 and TGF- blockade can safely enhance tumor antigen-specific immunity and highlight the feasibility of multi-mechanism neoadjuvant immunotherapy in patients with HPV-unrelated HNSCC.

CONCLUSION

Our studies provide new insight into the ability of neoadjuvant immunotherapy to induce polyclonal neoadjuvant-specific T cell responses in tumors and suggest that features of the tumor microenvironment, such as myeloid cell infiltration, may be a major determinant of enhanced anti-tumor immunity following such treatment.

420 PROSTVAC in combination with nivolumab enhanced immune cell infiltration in prostate cancer

Background

Prostate cancer (PC) is the most common non-cutaneous diagnosed cancer among men in USA.1 Although clinical outcomes are favorable for patients with localized disease, 20–30% of patients will develop metastatic prostate cancer (mPC) and have poor prognosis. Immunotherapy, as a single agent, provides benefit to a small subset of PC patients, which is thought to be partially due to its known cold tumor immune microenvironment (TIME). Combination studies are needed to enhance benefit.2 Prostvac is a therapeutic cancer vaccine engineered to activate an immune response against prostate-specific Antigen (PSA).3 Prostvac alone could induce systemic immune response by increasing immune-cell infiltrates in and around the tumor.4 In this study, we are exploring the effect of Prostvac in combination with nivolumab in TIME in prostate cancer.

Methods

We treated locally advanced prostate cancer patients (n=6) undergoing radical prostatectomy (RP) with neoadjuvant Prostvac in combination with nivolumab, an immune checkpoint PD-1 inhibitor. Dynamic changes in TIME before and after treatment were studied using multiplex immunofluorescence (Opal Method). Formalin fixed paraffin-embedded sections from matched pre-treated prostate biopsies and post-treated RP samples were stained with a validated T cell panel (DAPI, CD4, CD8, FOXP3, Ki67, Pan CK and PD-L1). To analyze the data, TIME was segmented into 3 compartments: intratumoral, invasive margin and benign.

Results

Combination immunotherapy significantly increased CD4+ T cell density in the invasive margin (mean 211.5 cells/mm2 vs 592.2 cells/mm2, p<0.05), with similar trend in the intratumoral and the benign compartments. CD8+ T cell density increased after treatment in the invasive margin (mean 47.25 cells/mm2 vs 157cells/mm2) and the benign compartment. 5/6 and 4/6 patients showed more than 2-fold increase of CD4 and CD8 T cells in the TIME, respectively, in at least one of the three compartments. Increased proliferative indices in CD4+ and CD8+ T cells were also seen after treatment. Tregs were present in low frequencies in TIME (maximum of 12 cells/mm2) with no significant changes. Moreover, a significant drop in tumor cell Ki67 after treatment (mean 252.8 cells/mm2 vs 100.5 cells/332, p<0.05) suggests that the combination may control tumor growth.

Conclusions

The combination of Neoadjuvant Prostvac and nivolumab was associated with increased immune cell infiltration in a cohort of early prostate cancer patients. A broader examination of the TIME and the role immune cells undertake to control tumor growth is on-going.

Trial Registration

NCT02933255

References

Siegel RL, Miller KD, Jemal A. Cancer statistics, 2020. CA Cancer J Clin (Internet) 2020;70:7–3

Zhao SG, Lehrer J, Chang SL, et al. The immune landscape of prostate cancer and nomination of PD-L2 as a potential therapeutic target. J Natl Cancer Inst 2018;111:301–10.

Madan RA, Arlen PM, Mohebtash M, et al. Prostvac-VF: a vectorbased vaccine targeting PSA in prostate cancer. Expert Opin Investig Drugs 2009;18:1001–11

Abdul Sater H, Marté JL, Donahue RN, et al. Neoadjuvant PROSTVAC prior to radical prostatectomy enhances T-cell infiltration into the tumor immune microenvironment in men with prostate cancer. J Immunother Cancer 2020;8(1):655–64

Ethics Approval

This study was performed in compliance with ethical standard and was approved by the NIH IRB, 17C-0007. All patients participating in this study gave an informed consent before taking part.

Abstract 4524: Comparison of PDX, PDC, and PDOrg models from the National Cancer Institute’s Patient-Derived Models Repository (PDMR)

The National Cancer Institute (NCI) has developed a Patient-Derived Models Repository (PDMR) comprised of quality-controlled, early-passage, clinically-annotated patient-derived tumor xenografts (PDXs), in vitro tumor cell cultures (PDCs), cancer associated fibroblasts (CAFs), and patient-derived organoids (PDOrg). NCI has focused on generating models to complement existing PDX collections and address unmet needs in the preclinical model space. These models are offered to the extramural community for research use (https://pdmr.cancer.gov), along with clinical annotation and molecular information (whole exome sequence, gene expression using RNASeq), via a publicly accessible database. Currently, over 200 PDX models, 50 PDC models, and 100 CAF models are available for distribution to the US research community. Approximately 50 PDOrg models will be released in early 2019. As part of its rare cancer initiative, the NCI is also targeting the collection of infrequently-observed tumor histologies to advance both biological investigations and drug development efforts for under-studied malignancies. Comparison of matched models, models where more than one model type are available (e.g., PDX and PDC), demonstrate a high degree of concordance across the model types. Genetic stability across the models is assessed using multiple criteria including genetic assessment of CNVs and presence of driver mutations. Optimal CNV assessment uses whole exome sequence data corrected for cellularity in the patient specimen using germline reads and corrected for cellularity in the PDX specimens by subtraction of the mouse reads. Histomorphologic comparison of PDXs and cell line xenografts (CLX) generated from in vitro PDCs and PDOrgs also overall show a high degree of concordance, though loss of features and dedifferentiation can be observed in some models. Overall these models demonstrate a high degree of conservation at the genetic and pathologic level when compared to the patient tumor. These models can provide researchers the ability to perform high- or mid-throughput screening in 2D or 3D culture followed by targeted selection of PDX models for in vivo studies. Funded by NCI Contract No. HHSN261200800001E

Citation Format: Yvonne A. Evrard, Dianne Newton, Biswajit Das, Sergio Y. Alcoser, Kaitlyn Arthur, Mariah Baldwin, Carrie Bonomi, Suzanne Borgel, John Carter, Tiffany Chase, Alice Chen, Lily Chen, Nikki E. Craig, Vivekananda Datta, Emily Delaney, Raymond Divelbiss, Kelly Dougherty, Thomas Forbes, Kyle Georgius, Joe Geraghty, Marion Gibson, Michelle M. Gottholm-Ahalt, Tara Grinnage-Pulley, Kelly Hedger, Sierra Hoffman, Chris Karlovich, Wiem Lassoued, Shahanawaz Jiwani, Candace Mallow, Chelsea McGlynn, Mallorie Morris, Jenna Moyer, Mike Mullendore, Matt Murphy, Rajesh Patidar, Kevin Plater, Marianne Radzyminski, Nicki Scott, Luke H. Stockwin, Howard Stotler, Jesse Stottlemyer, Savanna Styers, Debbie Trail, Tomas Vilimas, Anna Wade, Abigail Walke, Thomas Walsh, P. Mickey Williams, Melinda G. Hollingshead, James H. Doroshow. Comparison of PDX, PDC, and PDOrg models from the National Cancer Institute’s Patient-Derived Models Repository (PDMR) [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 4524.

Abstract 1056: Xenograft-associated B cell lymphoproliferative disease (XABLD) as a surrogate model to study Epstein-Barr virus (EBV) driven B cell Diseases

Background: Patient-derived tumor xenografts (PDX) are powerful tools to study cancer biology, cancer genomics and developmental therapeutics. A common problem in the development of PDX models is proliferation of atypical lymphocytes at the implantation site, which often overtake or limit the growth of the original tumor. This atypical lymphocyte proliferation has been described as XABLD in our PDX models. In this study, we characterized XABLD cases by morphology, immunophenotyping and genomic profiling. We hypothesize that XABLD tumors are morphologically and phenotypically similar to EBV-driven post-transplant lymphoproliferative disease (PTLD) and diffuse large B cell lymphoma (DLBCL). XABLD is a surrogate model to study EBV-driven PTLD and DLBCL.

Materials and Methods: Models were generated from patient tissue collected under NCI Tissue Procurement Protocol (clinicaltrials.gov: NCT00900198) and CIRB Tissue Procurement Protocol 9846 for development of models for NCI’s Patient-Derived Models Repository (https://pdmr.cancer.gov). Specimens were implanted subcutaneously in NOD/SCID/IL2Rg null (NSG) mice and animal health was monitored throughout the study. Tumors in mice with suspected XABLD were harvested and reviewed by histology and immunohistochemical analysis for CD45, B and T cell markers, EBV status, B-cell clonality assay. All samples were also classified by the Lymph2Cx NanoString cell of origin assay and transcriptome profiling.

Results: XABLD cases were found to originate from both solid tumor and circulating tumor cell implants. XABLD is a rapidly growing tumor positive for CD45, CD20, and LMP1 stains, 36 of 42 cases are strongly positive for PD-L1 stain. 39 of 42 cases exhibited an activated B cell (ABC) phenotype with evidence of elevated NF-kB signaling. Most cases were monoclonal for IGK/IGH and contained high numbers of tumor infiltrating CD8-positive T-cells with associated high mRNA expression of activated T cell markers.

Conclusion: The clinical presentation, morphology and molecular characteristics of XABLD cases were similar to EBV-driven DLBCL. As the XABLD models exhibited frequent PD-L1 expression and marked infiltration of CD8-positive T cells, they may be useful for in vitro evaluation of checkpoint inhibitor response and T cell antitumor activity.

Grant Support: This project has been funded in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261200800001E. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Citation Format: Tomas Vilimas, Gloryvee Rivera, Brandie Fullmer, Wiem Lassoued, Lindsay Dutko, Amanda Peach, Corinne Camalier, Li Chen, Rajesh Patidar, Suzanne Borgel, John Carter, Howard Stotler, Raymond Divelbiss, Jesse Stottlemyer, Michelle M. Gottholm-Ahalt, Michelle Crespo-Eugeni, Sean McDermott, William Jacob, Liqiang Xi, Pallavi Galera, Yvonne A. Evrard, Melinda G. Hollingshead, Elaine S. Jaffe, Mark Raffeld, Biswajit Das, Chris Karlovich, Vivekananda Datta, James H. Doroshow, P. Mickey Williams. Xenograft-associated B cell lymphoproliferative disease (XABLD) as a surrogate model to study Epstein-Barr virus (EBV) driven B cell Diseases [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 1056.

Abstract 1038: Xenograft-associated B cell lymphoproliferative disease as a surrogate model to study Epstein-Barr virus (EBV) driven lymphoma of the elderly

Background: Patient-derived tumor xenografts (PDX) are powerful tools to study cancer biology, cancer genomics and developmental therapeutics. A common problem in the development of PDX models is proliferation of atypical lymphocytes at the implant site, which often overtake or limit the growth of the original tumor. This atypical proliferation has been described as Xenograft-Associated B cell Lymphoproliferative Disease (XABLD) in our PDX models. In this study, we characterized XABLD cases by morphology, immunophenotyping and genomic profiling. We hypothesize that XABLD tumors are morphologically and phenotypically similar to EBV-driven lymphoma of the elderly and may function as a surrogate model for that lymphoma. Materials and Methods: Models were generated from patient tissue collected under NCI Tissue Procurement Protocol (clincialtrials.gov: NCT00900198) and CIRB Tissue Procurement Protocol 9846 for development of models for NCI's Patient-Derived Models Repository (https://pdmr.cancer.gov). Specimens were implanted subcutaneously in NOD/SCID/IL2Rg null (NSG) mice and animal health was monitored throughout the study. Tumors in mice with suspected XABLD were harvested and reviewed by histology and immunohistochemical analysis for CD45, B and T cell markers and EBV status. All samples in this study were classified by the Lymph2Cx NanoString cell of origin assay and transcriptome profiling. Results: XABLD-associated mice had rapidly growing CD45-positive tumors at the implantation site. Histopathological features were consistent with EBV-driven diffuse large B-cell lymphoma (DLBCL) primarily of polymorphous subtype. All XABLD specimens were diffusely positive for CD20 and EBNA, and most cases contained tumor infiltrating CD8-positive T-cells. Out of 42 cases, 36 were PD-L1-positive and 26 were PD-1-positive by IHC. 39 cases exhibited an activated B cell (ABC) phenotype, which is predominant in EBV-positive DLBCL. Conclusion: XABLD development has been seen across multiple patient histologies from both solid tumor and circulating tumor cells tissues of origin. The clinical presentation, morphology and molecular characteristics of XABLD cases were similar to EBV-driven DLBCL. As DLBCL is an aggressive disease with limited treatment options, our early-passage XABLD models may be useful in the preclinical evaluation of new therapies for EBV-positive DLBCL. Grant Support: This project has been funded in part with federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. HHSN261200800001E. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

Citation Format: Tomas Vilimas, Gloryvee Rivera, Brandie Fullmer, Wiem Lassoued, Lindsay Dutko, William Walsh, Amanda Peach, Corinne Camalier, Li Chen, Rajesh Patidar, Suzanne Borgel, John Carter, Howard Stotler, Raymond Divelbiss, Jesse Stottlemyer, Margaret Defreytas, Michelle M. Gottholm-Ahalt, Michelle A. Crespo-Eugeni, Sean McDermott, Yvonne A. Evrard, Melinda G. Hollingshead, Biswajit Das, Chris Karlovich, Vivekananda Datta, James H. Doroshow, P. Mickey Williams. Xenograft-associated B cell lymphoproliferative disease as a surrogate model to study Epstein-Barr virus (EBV) driven lymphoma of the elderly [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 1038.

Cell-based quantification of molecular biomarkers in histopathology specimens

AIMS

To investigate the use of a computer-assisted technology for objective, cell-based quantification of molecular biomarkers in specified cell types in histopathology specimens, with the aim of advancing current visual estimation and pixel-level (rather than cell-based) quantification methods.

METHODS AND RESULTS

Tissue specimens were multiplex-immunostained to reveal cell structures, cell type markers, and analytes, and imaged with multispectral microscopy. The image data were processed with novel software that automatically delineates and types each cell in the field, measures morphological features, and quantifies analytes in different subcellular compartments of specified cells.The methodology was validated with the use of cell blocks composed of differentially labelled cultured cells mixed in known proportions, and evaluated on human breast carcinoma specimens for quantifying human epidermal growth factor receptor 2, estrogen receptor, progesterone receptor, Ki67, phospho-extracellular signal-related kinase, and phospho-S6. Automated cell-level analyses closely matched human assessments, but, predictably, differed from pixel-level analyses of the same images.

CONCLUSIONS

Our method reveals the type, distribution, morphology and biomarker state of each cell in the field, and allows multiple biomarkers to be quantified over specified cell types, regardless of their abundance. It is ideal for studying specimens from patients in clinical trials of targeted therapeutic agents, for investigating minority stromal cell subpopulations, and for phenotypic characterization to personalize therapy and prognosis.

Effect of VEGF and VEGF Trap on vascular endothelial cell signaling in tumors

Vascular endothelial growth factor (VEGF) A is a major promoter of tumor angiogenesis and a prime target of antiangiogenic cancer therapy. To examine whether endothelial cell signaling might provide histological biomarkers of angiogenesis and VEGF activity in vivo, normal mouse organs and multiple tumor models were studied immunohistochemically for endothelial expression of activated ERK, STAT3, and AKT. Phospho(p)-ERK and p-STAT3 expression was negligible in the endothelia of normal organs but was significantly elevated in tumor endothelium. p-AKT was present at significant and comparable levels in both tumor and normal endothelia. In K1735 tumors induced to express more VEGF, endothelial p-ERK, p-STAT3 and p-AKT increased accompanied by signs of accelerated angiogenesis. Treatment of K1735 and Colo-205 tumors with the VEGF inhibitor, VEGF Trap (aflibercept), decreased tumor endothelial p-ERK, p-STAT3 and p-AKT expression accompanied by signs of antiangiogenic effect. These results show that endothelial p-ERK and p-STAT3 (but not p-AKT) distinguish tumor from normal vessels and that the presence of these two signaling intermediates may be useful indicators of tumor angiogenic activity and angiogenesis inhibition by VEGF antagonist.

Improved automatic detection and segmentation of cell nuclei in histopathology images

Automatic segmentation of cell nuclei is an essential step in image cytometry and histometry. Despite substantial progress, there is a need to improve accuracy, speed, level of automation, and adaptability to new applications. This paper presents a robust and accurate novel method for segmenting cell nuclei using a combination of ideas. The image foreground is extracted automatically using a graph-cuts-based binarization. Next, nuclear seed points are detected by a novel method combining multiscale Laplacian-of-Gaussian filtering constrained by distance-map-based adaptive scale selection. These points are used to perform an initial segmentation that is refined using a second graph-cuts-based algorithm incorporating the method of alpha expansions and graph coloring to reduce computational complexity. Nuclear segmentation results were manually validated over 25 representative images (15 in vitro images and 10 in vivo images, containing more than 7400 nuclei) drawn from diverse cancer histopathology studies, and four types of segmentation errors were investigated. The overall accuracy of the proposed segmentation algorithm exceeded 86%. The accuracy was found to exceed 94% when only over- and undersegmentation errors were considered. The confounding image characteristics that led to most detection/segmentation errors were high cell density, high degree of clustering, poor image contrast and noisy background, damaged/irregular nuclei, and poor edge information. We present an efficient semiautomated approach to editing automated segmentation results that requires two mouse clicks per operation.

Interferon-gamma-dependent infiltration of human T cells into neuroblastoma tumors in vivo

PURPOSE

To investigate the impact of interferon-gamma-mediated upregulation of major histocompatibility complex class I expression on tumor-specific T-cell cytotoxicity and T-cell trafficking into neuroblastoma tumors in vivo.

EXPERIMENTAL DESIGN

Restoration of major histocompatibility complex class I expression by interferon-gamma treatment enhances killing of neuroblastoma cells. To understand the potential of this approach in vivo, we developed a novel model of neuroblastoma in which NOD/scid/IL2R gamma(null) immunodeficient mice are engrafted with both human T cells and tumor cells.

RESULTS

Here, we show enhanced killing of neuroblastoma cells by patient-derived, tumor-specific T cells in vitro. In addition, interferon-gamma treatment in vivo induces efficient upregulation of major histocompatibility complex class I expression on neuroblastoma tumor cells, and this is accompanied by significantly enhanced infiltration of T cells into the tumor. In a pilot clinical trial in patients with high-risk neuroblastoma, we similarly observed augmented T-cell trafficking into neuroblastoma nests in tumor biopsy specimens obtained from patients after 5 days of systemic interferon-gamma therapy.

CONCLUSIONS

Interferon-gamma overcomes critical obstacles to the killing of human neuroblastoma cells by specific T cells. Together, these findings provide a rationale for the further testing of interferon-gamma as an approach for improving the efficacy of T cell-based therapies for neuroblastoma and other major histocompatibility complex class I-deficient malignancies. In addition, we describe a model that may expedite the preclinical screening of approaches aimed at augmenting T-cell trafficking into human tumors.

Activated STAT3 is a mediator and biomarker of VEGF endothelial activation

STAT3 plays important roles in cell proliferation and survival signaling and is often constitutively activated in transformed cells. In this study, we examined STAT3 activation in endothelial cells (EC) during angiogenic activation and therapeutic angiogenesis inhibition. VEGF stimulation of cultured EC induced STAT3 phosphorylation by a VEGFR2- and Src-dependent mechanism. FGF2 but not PlGF also induced EC STAT3 activation in vitro. Activated STAT3 mediated VEGF induction of EC Bcl-2 and contributed to VEGF protection of EC from apoptosis. In vivo, p-STAT3 was absent by immunohistological staining in the vascular EC of most normal mouse organs but was present in the vessels of mouse and human tumors. Tumor vascular p-STAT3 increased as tumors were induced to overexpress VEGF, indicating that VEGF is an activator of EC p-STAT3 in vivo. Tumor vascular p-STAT3 decreased during angiogenesis inhibition by antagonists of VEGF-VEGFR signaling, VEGF Trap and SU5416, indicating that VEGF contributed to the EC STAT3 activation seen in the tumors prior to treatment and that p-STAT3 may be used to monitor therapy. These studies show that p-STAT3 is a mediator and biomarker of endothelial activation that reports VEGF-VEGFR2 activity and may be useful for studying the pharmacodynamics of targeted angiogenesis inhibitors.

Sorafenib targets BRAF and VEGFR in metastatic thyroid carcinoma

6019

Background. There is no effective therapy for patients with metastatic thyroid cancer not cured by surgery or treatment with I131. Sorafenib is a promising multi-tyrosine kinase inhibitor for patients with metastatic PTC (mPTC). Although the primary targets of sorafenib are thought to include BRAF and VEGFR, this has been the subject of debate. Whether sorafenib primarily acts on the tumor cells (TC) or endothelial cells (EC) and how BRAF mutation status (45% of PTC harbor V600E) relates to response is also unknown. Methods. Responses of patients with metastatic, iodine-refractory PTC, enrolled into our phase II study of sorafenib were monitored by PET at 4 wks and CTs every 2 mos. Sorafenib activity was studied using immunohistochemistry (IHC) for pERK, pAKT, and pVEGFR-2, while Ki-67 showed proliferating cells in tumor tissue pre- and on treatment. BRAF mutation status was determined by DNA sequencing. Results. Of 15 patients, five patients achieved a PR, three are stable (SD), two progressed, and three patients with SD withdrew due to toxicity. Target lesions decreased on average 31%. Eight of 10 PET scans showed decreased activity at 4 weeks. IHC on tissue from 2 patients (at 1 and 2 wks, both BRAFwt) showed 50% decrease in pERK (downstream of VEGFR2 and BRAF) and 30% decrease in pAKT (downstream of VEGFR2). p-ERK and p-AKT were altered in both the TC and EC. Ki-67 decreased from 10% to <1%. No change in VEGFR-2 was seen; but, pVEGFR-2 completely disappeared in one sample while the other showed a small decrease. Quantitative analysis using a multispectral imaging system confirmed the changes observed by IHC. In tissue from a patient at 17 months on sorafenib, the decrease in pERK and pAKT appeared to be the same or reversed, suggesting compensatory changes in these pathways in resistant but stable disease. Conclusions. Our study shows the early clinical and biologic activity of sorafenib in patients with mPTC and the targets of early suppression. Importantly, it also reveals compensatory changes in target molecules in cells resistant to therapy. These cells are the likely source of tumor resistance that has been seen to develop to other similar targeted agents. Sorafenib is the first viable treatment option for patients with mPTC, and these results provide key insights into the mechanisms of action and resistance of this drug.

No significant financial relationships to disclose.

Inhibition of tumor endothelial ERK activation, angiogenesis, and tumor growth by sorafenib (BAY43-9006)

Activation of the Raf-MEK-ERK signal transduction pathway in endothelial cells is required for angiogenesis. Raf is the kinase most efficiently inhibited by the multikinase inhibitor sorafenib, which has shown activity against certain human cancers in clinical trials. To understand the mechanisms underlying this activity, we studied how it controlled growth of K1735 murine melanomas. Therapy caused massive regional tumor cell death accompanied by severe tumor hypoxia, decreased microvessel density, increased percentage of pericyte-covered vessels, and increased caliber and decreased arborization of vessels. These signs of K1735 angiogenesis inhibition, along with its ability to inhibit Matrigel neovascularization, showed that sorafenib is an effective anti-angiogenic agent. Extracellular signal-regulated kinase (ERK) activation in tumor endothelial cells, revealed by immunostaining for phospho-ERK and CD34, was inhibited, whereas AKT activation, revealed by phospho-AKT immunostaining, was not inhibited in K1735 and two other tumor types treated with sorafenib. Treatment decreased endothelial but not tumor cell proliferation and increased both endothelial cell and tumor cell apoptosis. These data indicate that sorafenib's anti-tumor efficacy may be primarily attributable to angiogenesis inhibition resulting from its inhibition of Raf-MEK-ERK signaling in endothelial cells. Assessing endothelial cell ERK activation in tumor bio-psies may provide mechanistic insights into and allow monitoring of sorafenib's activity in patients in clinical trials.