Tristan Grogan

PD-1 blockade induces responses by inhibiting adaptive immune resistance

Therapies that target the programmed death-1 (PD-1) receptor have shown unprecedented rates of durable clinical responses in patients with various cancer types. One mechanism by which cancer tissues limit the host immune response is via upregulation of PD-1 ligand (PD-L1) and its ligation to PD-1 on antigen-specific CD8+ T cells (termed adaptive immune resistance). Here we show that pre-existing CD8+ T cells distinctly located at the invasive tumour margin are associated with expression of the PD-1/PD-L1 immune inhibitory axis and may predict response to therapy. We analysed samples from 46 patients with metastatic melanoma obtained before and during anti-PD-1 therapy (pembrolizumab) using quantitative immunohistochemistry, quantitative multiplex immunofluorescence, and next-generation sequencing for T-cell antigen receptors (TCRs). In serially sampled tumours, patients responding to treatment showed proliferation of intratumoral CD8+ T cells that directly correlated with radiographic reduction in tumour size. Pre-treatment samples obtained from responding patients showed higher numbers of CD8-, PD-1- and PD-L1-expressing cells at the invasive tumour margin and inside tumours, with close proximity between PD-1 and PD-L1, and a more clonal TCR repertoire. Using multivariate analysis, we established a predictive model based on CD8 expression at the invasive margin and validated the model in an independent cohort of 15 patients. Our findings indicate that tumour regression after therapeutic PD-1 blockade requires pre-existing CD8+ T cells that are negatively regulated by PD-1/PD-L1-mediated adaptive immune resistance.

Role of Pancreatic Cancer-derived Exosomes in Salivary Biomarker Development

Background: Salivary biomarkers for systemic diseases have been undermined due to lack of mechanistic and biological rationale. Results: Suppression of exosome biogenesis leads to ablation of salivary biomarkers. Conclusion: Tumor-derived exosomes provide a mechanism for discriminatory biomarkers in saliva. Significance: Tumor-derived exosomes provide the scientific rationale that connects pancreatic tumors and the oral cavity leading to salivary biomarkers. Recent studies have demonstrated that discriminatory salivary biomarkers can be readily detected upon the development of systemic diseases such as pancreatic cancer, breast cancer, lung cancer, and ovarian cancer. However, the utility of salivary biomarkers for the detection of systemic diseases has been undermined due to the absence of the biological and mechanistic rationale as to why distal diseases from the oral cavity would lead to the development of discriminatory biomarkers in saliva. Here, we examine the hypothesis that pancreatic tumor-derived exosomes are mechanistically involved in the development of pancreatic cancer-discriminatory salivary transcriptomic biomarkers. We first developed a pancreatic cancer mouse model that yielded discriminatory salivary biomarkers by implanting the mouse pancreatic cancer cell line Panc02 into the pancreas of the syngeneic host C57BL/6. The role of pancreatic cancer-derived exosomes in the development of discriminatory salivary biomarkers was then tested by engineering a Panc02 cell line that is suppressed for exosome biogenesis, implanting into the C56BL/6 mouse, and examining whether the discriminatory salivary biomarker profile was ablated or disrupted. Suppression of exosome biogenesis results in the ablation of discriminatory salivary biomarker development. This study supports that tumor-derived exosomes provide a mechanism in the development of discriminatory biomarkers in saliva and distal systemic diseases.

Dynamic changes in intracellular ROS levels regulate airway basal stem cell homeostasis through Nrf2-dependent Notch signaling

Airways are exposed to myriad environmental and damaging agents such as reactive oxygen species (ROS), which also have physiological roles as signaling molecules that regulate stem cell function. However, the functional significance of both steady and dynamically changing ROS levels in different stem cell populations, as well as downstream mechanisms that integrate ROS sensing into decisions regarding stem cell homeostasis, are unclear. Here, we show in mouse and human airway basal stem cells (ABSCs) that intracellular flux from low to moderate ROS levels is required for stem cell self-renewal and proliferation. Changing ROS levels activate Nrf2, which activates the Notch pathway to stimulate ABSC self-renewal and an antioxidant program that scavenges intracellular ROS, returning overall ROS levels to a low state to maintain homeostatic balance. This redox-mediated regulation of lung stem cell function has significant implications for stem cell biology, repair of lung injuries, and diseases such as cancer.

Treatment Response Evaluation using 18F-FDOPA PET in Patients with Recurrent Malignant Glioma on Bevacizumab Therapy

Purpose: This study compares the value of 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine (18F-FDOPA) positron emission tomography (PET) and MRI in assessing outcome during antiangiogenic treatment in patients with recurrent high-grade gliomas. Experimental Design: Thirty patients were prospectively studied with 18F-FDOPA PET scans immediately before, and two and six weeks after start of bevacizumab therapy. 18F-FDOPA metabolic tumor volumes (MTV) as well as max and mean standardized uptake values (SUV) within this MTV were obtained. MRI treatment response was assessed at six weeks. The predictive ability of 18F-FDOPA PET and MRI response assessment were evaluated with regard to progression-free survival (PFS) and overall survival (OS). Results: A total of 30, 28, and 24 18F-FDOPA PET scans at baseline, two weeks, and six weeks, were available for analysis, respectively. 18F-FDOPA PET SUVs as well as their changes through therapy were not predictive of outcome. However, MTV parameters such as MTV changes were highly prognostic. Interestingly, absolute MTV at the first follow up scan provides the most significant prediction for increased OS (P < 0.0001) as well as PFS (P = 0.001). This surprising result was scrutinized with cross-validation and simulation analysis. Responders based on 18F-FDOPA PET data survived 3.5 times longer (12.1 months vs. 3.5 months, median OS, P < 0.001) than nonresponders (17 patients vs. 11 patients, respectively). In comparison, responders based on MRI data lived 1.5 times longer (11.4 months vs 7.7 months, P = 0.03) than nonresponders (22 patients vs. 7 patients, respectively). Conclusions: 18F-FDOPA PET identifies treatment responders to antiangiogenic therapy as early as two weeks after treatment initiation. Clin Cancer Res; 20(13); 3550–9. ©2014 AACR.

Modification of hematopoietic stem/progenitor cells with CD19-specific chimeric antigen receptors as a novel approach for cancer immunotherapy.

Chimeric antigen receptors (CARs) against CD19 have been shown to direct T-cells to specifically target B-lineage malignant cells in animal models and clinical trials, with efficient tumor cell lysis. However, in some cases, there has been insufficient persistence of effector cells, limiting clinical efficacy. We propose gene transfer to hematopoietic stem/progenitor cells (HSPC) as a novel approach to deliver the CD19-specific CAR, with potential for ensuring persistent production of effector cells of multiple lineages targeting B-lineage malignant cells. Assessments were performed using in vitro myeloid or natural killer (NK) cell differentiation of human HSPCs transduced with lentiviral vectors carrying first and second generations of CD19-specific CAR. Gene transfer did not impair hematopoietic differentiation and cell proliferation when transduced at 1-2 copies/cell. CAR-bearing myeloid and NK cells specifically lysed CD19-positive cells, with second-generation CAR including CD28 domains being more efficient in NK cells. Our results provide evidence for the feasibility and efficacy of the modification of HSPC with CAR as a strategy for generating multiple lineages of effector cells for immunotherapy against B-lineage malignancies to augment graft-versus-leukemia activity.

Head and Neck Sarcomas: Analysis of the SEER Database

Objective To summarize the epidemiology of sarcomas occurring in the head and neck and identify prognostic factors for patient survival. Study Design and Setting Cross-sectional analysis of the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) program. Methods The SEER 18 registries, comprising sarcoma diagnoses made from 1973 to 2010, were queried for sarcomas arising in the head and neck. Pediatric and adult patients were analyzed separately, and multivariate and propensity-matched analyses were performed to identify predictors of disease-specific survival. Results In all, 11,481 adult cases and 1244 pediatric cases were identified. In adults, the most common histologic subtypes were malignant fibrous histiocytoma (MFH), Kaposi sarcoma, and hemangiosarcoma, while in the pediatric cohort, the most common histologic subtypes were rhabdomyosarcoma, MFH, and osteosarcoma. Cause-specific 2-, 5-, and 10-year survival rates were 76%, 66%, and 61% for adults and 84%, 73%, and 71% for pediatric patients. Multivariate analysis performed for adults revealed that male gender, absence of radiation therapy, and stage I disease were associated with improved cause-specific survival reaching statistical significance. However, a propensity-matched model demonstrated no significant difference in cause-specific survival between patients who received radiation and those who did not. Conclusion Sarcomas, a heterogeneous group of malignant mesenchymal tumors, are uncommonly found in the head and neck. This study represents the largest analysis of patients with head and neck sarcomas in the literature and demonstrates the impact of age, gender, primary site, histology, and radiation status on overall prognosis.

Randomized Clinical Trial of Brewed Green and Black Tea in Men With Prostate Cancer Prior to Prostatectomy

Preclinical and epidemiologic studies suggest chemopreventive effects of green tea (GT) and black tea (BT) in prostate cancer. In the current study we determined the effect of GT and BT consumption on biomarkers related to prostate cancer development and progression.

PGE2-Driven Expression of c-Myc and OncomiR-17-92 Contributes to Apoptosis Resistance in NSCLC

Aberrant expression of microRNAs (miRNA) with oncogenic capacities (oncomiRs) has been described for several different malignancies. The first identified oncomiR, miR-17-92, is frequently overexpressed in a variety of cancers and its targets include the tumor suppressor PTEN. The transcription factor c-Myc (MYC) plays a central role in proliferative control and is rapidly upregulated upon mitogenic stimulation. Expression of c-Myc is frequently deregulated in tumors, facilitating proliferation and inhibiting terminal differentiation. The c-Myc–regulated network comprises a large number of transcripts, including those encoding miRNAs. Here, prostaglandin E2 (PGE2) exposure rapidly upregulates the expression of the MYC gene followed by the elevation of miR-17-92 levels, which in turn suppresses PTEN expression, thus enhancing apoptosis resistance in non–small cell lung cancer (NSCLC) cells. Knockdown of MYC expression or the miR-17-92 cluster effectively reverses this outcome. Similarly, miR-17-92 levels are significantly elevated in NSCLC cells ectopically expressing COX-2. Importantly, circulating miR-17-92 was elevated in the blood of patients with lung cancer as compared with subjects at risk for developing lung cancer. Furthermore, in patients treated with celecoxib, miR-17-92 levels were significantly reduced. These data demonstrate that PGE2, abundantly produced by NSCLC and inflammatory cells in the tumor microenvironment, is able to stimulate cell proliferation and promote resistance to pharmacologically induced apoptosis in a c-Myc and miR-17-92–dependent manner. Implications: This study describes a novel mechanism, involving c-Myc and miR-17-92, which integrates cell proliferation and apoptosis resistance. Mol Cancer Res; 12(5); 765–74. ©2014 AACR.

Impaired Preadipocyte Differentiation Into Adipocytes in Subcutaneous Abdominal Adipose of PCOS-Like Female Rhesus Monkeys

Metabolic characteristics of polycystic ovary syndrome women and polycystic ovary syndrome-like, prenatally androgenized (PA) female monkeys worsen with age, with altered adipogenesis of sc abdominal adipose potentially contributing to age-related adverse effects on metabolism. This study examines whether adipocyte morphology and gene expression in sc abdominal adipose differ between late reproductive-aged PA female rhesus monkeys compared with age-matched controls (C). Subcutaneous abdominal adipose of both groups was obtained for histological imaging and mRNA determination of zinc finger protein 423 (Zfp423) as a marker of adipose stem cell commitment to preadipocytes, and CCAAT/enhancer binding protein (C/EBP)α/peroxisome proliferator-activated receptor (PPAR)δ as well as C/EBPα/PPARγ as respective markers of early- and late-stage differentiation of preadipocytes to adipocytes. In all females combined, serum testosterone (T) levels positively correlated with fasting serum levels of total free fatty acid (r(2) = 0.73, P < .002). PA females had a greater population of small adipocytes vs C (P < .001) in the presence of increased Zfp423 (P < .025 vs C females) and decreased C/EBPα (P < .003, vs C females) mRNA expression. Moreover, Zfp423 mRNA expression positively correlated with circulating total free fatty acid levels during iv glucose tolerance testing (P < .004, r(2) = 0.66), whereas C/EBPα mRNA expression negatively correlated with serum T levels (P < .02, r(2) = 0.43). Gene expression of PPARδ and PPARγ were comparable between groups (P = .723 and P = .18, respectively). Early-to-mid gestational T excess in female rhesus monkeys impairs adult preadipocyte differentiation to adipocytes in sc abdominal adipose and may constrain the ability of this adipose depot to safely store fat with age.

Liver Metastasis and Treatment Outcome with Anti-PD-1 Monoclonal Antibody in Patients with Melanoma and NSCLC

The association between metastatic site and responses to anti-PD-1 immunotherapy was explored In both melanoma and lung cancer. Liver metastasis was associated with worse outcome and CD8+ T cell-poor tumors, suggesting a potential mechanism for the outcomes. We explored the association between liver metastases, tumor CD8+ T-cell count, and response in patients with melanoma or lung cancer treated with the anti-PD-1 antibody, pembrolizumab. The melanoma discovery cohort was drawn from the phase I Keynote 001 trial, whereas the melanoma validation cohort was drawn from Keynote 002, 006, and EAP trials and the non–small cell lung cancer (NSCLC) cohort from Keynote 001. Liver metastasis was associated with reduced response and shortened progression-free survival [PFS; objective response rate (ORR), 30.6%; median PFS, 5.1 months] compared with patients without liver metastasis (ORR, 56.3%; median PFS, 20.1 months) P ≤ 0.0001, and confirmed in the validation cohort (P = 0.0006). The presence of liver metastasis significantly increased the likelihood of progression (OR, 1.852; P < 0.0001). In a subset of biopsied patients (n = 62), liver metastasis was associated with reduced CD8+ T-cell density at the invasive tumor margin (liver metastasis+ group, n = 547 ± 164.8; liver metastasis− group, n = 1,441 ± 250.7; P < 0.016). A reduced response rate and shortened PFS was also observed in NSCLC patients with liver metastasis [median PFS, 1.8 months; 95% confidence interval (CI), 1.4–2.0], compared with those without liver metastasis (n = 119, median PFS, 4.0 months; 95% CI, 2.1–5.1), P = 0.0094. Thus, liver metastatic patients with melanoma or NSCLC that had been treated with pembrolizumab were associated with reduced responses and PFS, and liver metastases were associated with reduced marginal CD8+ T-cell infiltration, providing a potential mechanism for this outcome. Cancer Immunol Res; 5(5); 417–24. ©2017 AACR.