A biogeographical appraisal of the threatened South East Africa Montane Archipelago ecoregion

Recent biological surveys of ancient inselbergs in southern Malawi and northern Mozambique have led to the discovery and description of many species new to science, and overlapping centres of endemism across multiple taxa. Combining these endemic taxa with data on geology and climate, we propose the 'South East Africa Montane Archipelago' (SEAMA) as a distinct ecoregion of global biological importance. The ecoregion encompasses 30 granitic inselbergs reaching > 1000 m above sea level, hosting the largest (Mt Mabu) and smallest (Mt Lico) mid-elevation rainforests in southern Africa, as well as biologically unique montane grasslands. Endemic taxa include 127 plants, 45 vertebrates (amphibians, reptiles, birds, mammals) and 45 invertebrate species (butterflies, freshwater crabs), and two endemic genera of plants and reptiles. Existing dated phylogenies of endemic animal lineages suggests this endemism arose from divergence events coinciding with repeated isolation of these mountains from the pan-African forests, together with the mountains' great age and relative climatic stability. Since 2000, the SEAMA has lost 18% of its primary humid forest cover (up to 43% in some sites)-one of the highest deforestation rates in Africa. Urgently rectifying this situation, while addressing the resource needs of local communities, is a global priority for biodiversity conservation.

Differing impacts of the COVID-19 pandemic on farmers and intermediaries: insights into the Ecuadorian cocoa value chain

The COVID-19 pandemic generated diverse impacts and responses in agricultural value chains worldwide. Cocoa is a key crop for Ecuadorian exports, and the analysis of effects the pandemic had on value chain actors contributes to the understanding of their individual capacities to coping with a major shock. The purpose of this study was to assess the number and severity of impacts and responses implemented by two links in the cocoa value chain to the pandemic, based on a survey of 158 cocoa farmers and 52 cocoa intermediaries from the main cocoa-producing provinces of the northern coast of Ecuador in 2021. Surveyed farmers and part of the intermediaries form part of the sustainability program of a large Swiss chocolate manufacturer. The impacts and responses reported were grouped into seven resources according to the Activity System Approach. Then, a comparison between groups was applied using the Wilcoxon rank sum test for nonparametric data, determining the most severe impacts and effective resilience responses among the actors. The results reveal that farmers and intermediaries were similarly affected by the pandemic, reporting 21 and 16 negative impacts, respectively. Farmers experienced a higher number and severity of impacts on financial and social resources, while intermediaries on human and material resources. The strongest impact was the loss of sales, reported by 65% of farmers and 58% of intermediaries. Farmers implemented more social responses that they judged highly effective, while intermediaries implemented more human responses that they judged highly effective. Public policy should enhance the social resources of farmers by strengthening their associativity and the capacities of their members, as mechanisms to mitigate their vulnerability to future health and climate crises. The financial resources of both actors should be protected through public credit and agricultural insurance.

Bovine congenital defects recorded by veterinary practitioners

A mobile phone app was used by 59 veterinary practitioners to collect case histories and images of 191 cattle with congenital defects distributed nationally over a 3-year period. The majority of cases were recorded during the spring calving season (57.6%) in pluriparous dairy dams. The majority of calves were recorded at birth or within the first week (66.5%) in singletons born at full-term. On the majority of farms (75.9%), this was the only congenitally deformed bovine recorded up to that point in the year and on the majority of farms, there were no congenitally deformed cattle recorded in the previous 5 years. The majority of congenital defects (83.5%) were recorded in the musculoskeletal or digestive systems. The three most commonly recorded individual defects were intestinal atresia (24.1%), schistosomus reflexus (20.4%) and ankylosis (6.8%); multiple defects were recorded in 13.1% of cases. These findings highlight the relatively high prevalence of intestinal atresia and schistosomus reflexus in calves attended by veterinary practitioners, which warrants implementation of preventive measures. The project highlights the potential benefits of veterinary-practitioner apps to detect changing trends in endemic, or the emergence of novel, congenital or other conditions.

Galectin-3 Cooperates with CD47 to Suppress Phagocytosis and T-cell Immunity in Gastric Cancer Peritoneal Metastases

The peritoneal cavity is a common site of gastric adenocarcinoma (GAC) metastasis. Peritoneal carcinomatosis (PC) is resistant to current therapies and confers poor prognosis, highlighting the need to identify new therapeutic targets. CD47 conveys a "don't eat me" signal to myeloid cells upon binding its receptor signal regulatory protein alpha (SIRPα), which helps tumor cells circumvent macrophage phagocytosis and evade innate immune responses. Previous studies demonstrated that the blockade of CD47 alone results in limited clinical benefits, suggesting that other target(s) might need to be inhibited simultaneously with CD47 to elicit a strong antitumor response. Here, we found that CD47 was highly expressed on malignant PC cells, and elevated CD47 was associated with poor prognosis. Galectin-3 (Gal3) expression correlated with CD47 expression, and coexpression of Gal3 and CD47 was significantly associated with diffuse type, poor differentiation, and tumor relapse. Depletion of Gal3 reduced expression of CD47 through inhibition of c-Myc binding to the CD47 promoter. Furthermore, injection of Gal3-deficient tumor cells into either wild-type and Lgals3-/- mice led to a reduction in M2 macrophages and increased T-cell responses compared with Gal3 wild-type tumor cells, indicating that tumor cell-derived Gal3 plays a more important role in GAC progression and phagocytosis than host-derived Gal3. Dual blockade of Gal3 and CD47 collaboratively suppressed tumor growth, increased phagocytosis, repolarized macrophages, and boosted T-cell immune responses. These data uncovered that Gal3 functions together with CD47 to suppress phagocytosis and orchestrate immunosuppression in GAC with PC, which supports exploring a novel combination therapy targeting Gal3 and CD47.

SIGNIFICANCE

Dual inhibition of CD47 and Gal3 enhances tumor cell phagocytosis and reprograms macrophages to overcome the immunosuppressive microenvironment and suppress tumor growth in peritoneal metastasis of gastric adenocarcinoma.

Pan-cancer T cell atlas links a cellular stress response state to immunotherapy resistance

Tumor-infiltrating T cells offer a promising avenue for cancer treatment, yet their states remain to be fully characterized. Here we present a single-cell atlas of T cells from 308,048 transcriptomes across 16 cancer types, uncovering previously undescribed T cell states and heterogeneous subpopulations of follicular helper, regulatory and proliferative T cells. We identified a unique stress response state, TSTR, characterized by heat shock gene expression. TSTR cells are detectable in situ in the tumor microenvironment across various cancer types, mostly within lymphocyte aggregates or potential tertiary lymphoid structures in tumor beds or surrounding tumor edges. T cell states/compositions correlated with genomic, pathological and clinical features in 375 patients from 23 cohorts, including 171 patients who received immune checkpoint blockade therapy. We also found significantly upregulated heat shock gene expression in intratumoral CD4/CD8+ cells following immune checkpoint blockade treatment, particularly in nonresponsive tumors, suggesting a potential role of TSTR cells in immunotherapy resistance. Our well-annotated T cell reference maps, web portal and automatic alignment/annotation tool could provide valuable resources for T cell therapy optimization and biomarker discovery.

Abstract 5073: NT219 induces tumor PD-L1 expression and potentiates anti-PD-1 efficacy

While the advent of immune checkpoint blockade (ICB) has dramatically improved the prognosis of many immune-infiltrated cancers, for others, unfortunately, these benefits have yet to be realized. The major challenge before the field, then, is to identify combination therapies that act both to combat evolved resistance. NT219 is a novel dual inhibitor of insulin receptor substrates 1 and 2 (IRS) and STAT3. NT219 demonstrated antitumor effects against both in situ and metastatic human melanoma models in mice as a stand-alone treatment and in combination with mutated BRAF and MEK inhibitors. The potential of NT219 to overcome resistance and increase efficacy was demonstrated in PDX models with multiple drug classes. Collectively, these findings provided preclinical proof-of-concept NT219 as a promising novel cancer therapy. Given this data, the goal of our study was to assess the efficacy of combining NT219 with anti-PD-1 and anti-CTLA-4 ICB, and test capacity of the combination to overcome immune resistance. To that end, we have examined PD-L1 expression levels in vitro following NT219 treatment in two different strains of melanoma cells, B16-tdTomato (TMT) and B16 3I-F4, ICB sensitive and ICB resistant derivative lines, respectively. In addition, to evaluate the combination effect of NT219 with ICB therapy in ICB-resistant PDX model, we used a humanized PDX model of pembrolizumab-resistant gastroesophageal tumor (GEJ). These mice were injected with PBMCs from the same patient. Using multiple syngeneic immunocompetent models of melanoma (TMT and 3I-F4 cells) and the humanized PDX model, we investigated the potential of each ICB with NT219. Our findings showed that NT219 increased PD-L1 expression levels on both melanoma cell lines in vitro, however, the PD-L1 expression levels were much more elevated 3I-F4 than TMT cells. Interestingly, the levels of both IRS and activated pSTAT3, the targets of NT219, which consist well known resistance mechanisms, were higher in the resistant cells as compared to the sensitive line. In accordance we found that NT219 was able to restore anti-PD-1 sensitivity in 3I-F4 model (TGI = 58%) in the syngeneic model, promoting tumor rejection and increasing survival rates. The combined approach between NT219 and anti-CTLA-4 displayed a moderate effect (TGI = 37%). In the TMT, NT219 combined with anti-PD-1 showed greater efficacy compared to anti-PD-1 alone (TGI = 63% and TGI = 47%, respectively). These results were confirmed using the humanized ICB-resistant PDX model, where impressive synergy between NT219 and the anti-PD-1 (TGI = 98%) was demonstrated. To summarize, we found a significant synergistic effect of NT219 combined with anti-PD-1 therapy, supported by a mechanism of PDL-1 induction making ICB resistant tumors amenable to ICB treatment. Collectively, these findings demonstrated that NT219 has the potential to reverse ICB resistance in both human PDX and murine syngeneic tumor model systems

Citation Format: Ricardo Alexandre de Azevedo, Hadas Reuveni, Menashe Bar-Eli, Michael Curran. NT219 induces tumor PD-L1 expression and potentiates anti-PD-1 efficacy. [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 5073.

IL6 Mediates Suppression of T- and NK-cell Function in EMT-associated TKI-resistant EGFR-mutant NSCLC

PURPOSE

Patients with advanced non-small cell lung cancer (NSCLC) harboring activating EGFR mutations are initially responsive to tyrosine kinase inhibitors (TKI). However, therapeutic resistance eventually emerges, often via secondary EGFR mutations or EGFR-independent mechanisms such as epithelial-to-mesenchymal transition. Treatment options after EGFR-TKI resistance are limited as anti-PD-1/PD-L1 inhibitors typically display minimal benefit. Given that IL6 is associated with worse outcomes in patients with NSCLC, we investigate whether IL6 in part contributes to this immunosuppressed phenotype.

EXPERIMENTAL DESIGN

We utilized a syngeneic genetically engineered mouse model (GEMM) of EGFR-mutant NSCLC to investigate the effects of IL6 on the tumor microenvironment and the combined efficacy of IL6 inhibition and anti-PD-1 therapy. Corresponding in vitro studies used EGFR-mutant human cell lines and clinical specimens.

RESULTS

We identified that EGFR-mutant tumors which have oncogene-independent acquired resistance to EGFR-TKIs were more mesenchymal and had markedly enhanced IL6 secretion. In EGFR-mutant GEMMs, IL6 depletion enhanced activation of infiltrating natural killer (NK)- and T-cell subpopulations and decreased immunosuppressive regulatory T and Th17 cell populations. Inhibition of IL6 increased NK- and T cell-mediated killing of human osimertinib-resistant EGFR-mutant NSCLC tumor cells in cell culture. IL6 blockade sensitized EGFR-mutant GEMM tumors to PD-1 inhibitors through an increase in tumor-infiltrating IFNγ+ CD8+ T cells.

CONCLUSIONS

These data indicate that IL6 is upregulated in EGFR-mutant NSCLC tumors with acquired EGFR-TKI resistance and suppressed T- and NK-cell function. IL6 blockade enhanced antitumor immunity and efficacy of anti-PD-1 therapy warranting future clinical combinatorial investigations.

Cell-directed aptamer therapeutic targeting for cancers including those within the central nervous system

Osteopontin (OPN) is produced by tumor cells as well as by myeloid cells and is enriched in the tumor microenvironment (TME) of many cancers. Given the roles of OPN in tumor progression and immune suppression, we hypothesized that targeting OPN with aptamers that have high affinity and specificity could be a promising therapeutic strategy. Bi-specific aptamers targeting ligands for cellular internalization were conjugated to siRNAs to suppress OPN were created, and therapeutic leads were selected based on target engagement and in vivo activity. Aptamers as carriers for siRNA approaches were created including a cancer targeting nucleolin aptamer Ncl-OPN siRNA and a myeloid targeting CpG oligodeoxynucleotide (ODN)-OPN siRNA conjugate. These aptamers were selected as therapeutic leads based on 70–90% OPN inhibition in cancer (GL261, 344SQ, 4T1B2b) and myeloid (DC2.4) cells relative to scramble controls. In established immune competent 344SQ lung cancer and 4T1B2b breast cancer models, these aptamers, including in combination, demonstrate therapeutic activity by inhibiting tumor growth. The Ncl-OPN siRNA aptamer demonstrated efficacy in an immune competent orthotopic glioma model administered systemically secondary to the ability of the aptamer to access the glioma TME. Therapeutic activity was demonstrated using both aptamers in a breast cancer brain metastasis model. Targeted inhibition of OPN in tumor cells and myeloid cells using bifunctional aptamers that are internalized by specific cell types and suppress OPN expression once internalized may have clinical potential in cancer treatment.

592 ATR-mediated CD47 and PD-L1 upregulation restricts radiotherapy-induced immune priming and abscopal responses in colorectal cancer

Background

Background: Radiotherapy of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)-expressing CRC cells systemically; however, incidences of abscopal tumor remission are extremely rare. We sought to unravel the post-irradiation immune escape mechanisms in CRC.

Methods

Methods

Flow cytometry, gene knockdown, RNA and T cell receptor sequencing, and multiple murine syngeneic CRC models were used to interrogate mechanisms of CRC immune evasion following radiotherapy. Comparison of immunohistochemistry staining between pretreatment biopsy and post-irradiation surgical specimens was performed in rectal patients who underwent neoadjuvant radiotherapy with 5 Gy for 5 fractions.

Results

Results

We find that CRC cells utilize a common DNA repair signaling pathway — ATR/Chk1/STAT3 — to upregulate both CD47 and PD-L1 in response to radiotherapy, which through engagement of SIRPα and PD-1 suppresses the capacity of antigen-presenting cells (APCs) to phagocytose them thereby preventing TAA cross-presentation. This post-irradiation CD47 and PD-L1 upregulation can be observed in CRC cells treated with either photon or proton radiotherapy and across a wide variety of human solid tumor cells. Concordantly, rectal cancer patients who responded poorly (tumor regression grade 4–5, n = 10) to neoadjuvant radiotherapy exhibited significantly elevated post-irradiation CD47 levels (P = 0.005). In murine CRC models, the combination of radiotherapy, αSIRPα, and αPD-1 (RSP) profoundly enhances TAA uptake, activation of innate immune sensors, and TAA cross-priming across various antigen-presenting myeloid populations in the irradiated tumor microenvironment and facilitates TAA-presenting APC migration to secondary lymphoid organs. Furthermore, we observed robust production of TAA-specific CD8 T cells, functional activation of effector T cells, and increased tumor-infiltrating T cell clonality and clonal diversity in mice treated with RSP. Importantly, radiotherapy coupled with phagocytosis checkpoint blockade significantly improves complete response rates in both irradiated and abscopal tumors and prolongs survival in three distinct murine CRC models, including a cecal orthotopic model. In addition, αSIRPα exerts superior tumoricidal efficacy than αCD47 in combination with RT and αPD-1. We find RSP efficacy to be STING dependent as knockout animals lose most benefit of phagocytosis checkpoint blockade.

Conclusion

ATR-mediated CD47 and PD-L1 upregulation restrains radiation-induced immune priming in CRC. Blockade of the phagocytosis checkpoints SIRPα and PD-1 during radiotherapy promotes vigorous anti-CRC immune priming leading to systemic tumor regression.

Acknowledgements

This study is supported in part by NIH grant P30 CA16672, the MD Anderson Andrew Sabin Family Fellowship, and Chang Gung Memorial Hospital grant CMRPG3K1751. RCH was supported by the CPRIT Research Training Grant (RP170067) and Ralph B. Arlinghaus Ph.D. Scholarship. The authors are grateful to the members of the Advanced Cytometry & Sorting Facility at South Campus, Tissue Bank of Chang Gung Memorial Hospital at Linkou, and MHC Tetramer Core Facility at Baylor College of Medicine for their invaluable help.

Ethics Approval

This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital, Taiwan; approval number: 202001191B0C601.

The effectiveness of exercise interventions to increase physical activity in Cystic Fibrosis: A systematic review

Physical activity (PA) and exercise have numerous benefits in Cystic Fibrosis (CF) including improved lung function, exercise capacity and quality of life. Despite these benefits, the effectiveness of interventions to promote PA in this population are still largely unknown. The objective of this review was to synthesise existing research and determine whether exercise interventions are effective in promoting PA in people with CF. Using the PRISMA guidelines, a comprehensive search was conducted. Fifteen studies (463 participants) met the inclusion criteria. Eleven studies demonstrated improvements in PA in both short- and long-term interventions. However, the interventions were variable across the included studies, with a large inconsistency in PA assessment tools used. Aerobic training and activity counselling were the two elements identified in this review which most consistently improved PA. Future research should consider larger sample sizes and the use of accurate instruments to assess and track PA levels longitudinally.

622 Disrupted oxygen supply and tumor hyper- oxygen consumption contribute independently to prostate cancer immune privilege

Background

Despite the success of immunotherapy in immune-infiltrated ”hot” tumors like melanoma, ”cold” tumors like prostate cancer remain unresponsive [1,2,3]. We find that these tumors harbor regions of hypoxia that act as islands of immune privilege that exclude T cells, while retaining immunosuppressive myeloid cells. Targeting hypoxia using the hypoxia-activated prodrug, TH-302 (Evofosfamide) reduced hypoxic regions and co-operated with immune checkpoint blockade (anti-CTLA-4+anti PD-1) to drive tumor regression in transplantable and spontaneous murine prostate tumors [4]. In a Phase I clinical trial, the combination of Evofosfamide and anti CTLA-4 (Ipilimumab) elicited both objective responses and prolonged disease stabilization in late-stage ”cold” tumor patients. However, Evofosfamide reduces but does not eliminate hypoxia and patient tumors resistant to treatment with Evofosfamide and Ipilimumab were hyper-metabolic [5]. Heightened tumor oxidative metabolism has been shown to generate hypoxic zones that resist PD-1 blockade therapy [6] and treatment with Metformin, a mitochondrial complex I inhibitor may reduce hypoxia and improve responses [7]. We hypothesized that targeting tumor oxidative metabolism using mitochondrial complex I inhibitors might diminish tumor hypoxia and, in conjunction with Evofosfamide, sensitize unresponsive tumors to immunotherapy.

Methods

We investigated the capacity of two mitochondrial complex I inhibitors to reduce tumor oxidative metabolism, diminish myeloid suppressive capacity and improve anti-tumor T cell immunity, alone and in combination with Evofosfamide and checkpoint blockade. We assessed tumor burden and immune composition and characterized metabolic profiles using Seahorse XFe96 analyzer (Agilent).

Results

While Evofosfamide or inhibition of oxidative metabolism alone did not significantly impact tumor regression, dual combination and triple combination with checkpoint blockade led to a significant reduction in tumor burden. Assessment of the tumor immune microenvironment identified improvements in CD8 and CD4 effector T cell proliferation. In vitro metabolic and functional profiling of TRAMP-C2 prostate tumors, pre-activated T cells and myeloid derived suppressor cells revealed differential effects of complex I inhibition, with inhibition resulting in reduced tumor proliferation and myeloid suppressive function but increases in proliferation and cytotoxic function of pre-activated T cells.

Conclusions

Our findings indicate that tumor hypoxia and associated immune suppressive programming can be reduced through both local tissue remodeling and limitation of tumor oxygen metabolism. Complex I inhibition selectively inhibits tumor and myeloid cell function, while sparing T cells. This provides opportunities to craft synergistic immuno-metabolic therapies with the potential to treat ”cold” tumor patients refractory to current FDA approved immunotherapeutics.

References

Curran MA, Montalvo W, Yagita H, and Allison JP. PD-1 and CTLA-4 combination blockade expands infiltrating T cells and reduces regulatory T and myeloid cells within B16 melanoma tumors. Proc Natl Acad Sci U S A. 2010; 107(9): 4275–80.

Wolchok JD, Kluger H, Callahan MK, Postow MA, Rizvi NA, Lesokhin AM, et al. Nivolumab plus ipilimumab in advanced melanoma. N Engl J Med. 2013; 369(2): 122–33.

Kwon ED, Drake CG, Scher HI, Fizazi K, Bossi A, van den Eertwegh AJ, et al. Ipilimumab versus placebo after radiotherapy in patients with metastatic castration-resistant prostate cancer that had progressed after docetaxel chemotherapy (CA184-043): a multicentre, randomised, doubleblind, phase 3 trial. Lancet Oncol. 2014;15(7):700–12.

Jayaprakash P, Ai M, Liu A, Budhani P, Bartkowiak T, Sheng J, et al. Targeted hypoxia reduction restores T cell infiltration and sensitizes prostate cancer to immunotherapy. J Clin Invest. 2018; 128 (11): 5137–5149.

Hegde A, Jayaprakash P, Couillault CA, Piha-Paul S, Karp D, Rodon J, et al. A Phase I Dose-Escalation Study to Evaluate the Safety and Tolerability of Evofosfamide in Combination with Ipilimumab in Advanced Solid Malignancies. Clin Cancer Res. 2021; 27(11): 3050–3060.

Najjar YG, Menk AV, Sander C, Rao U, Karunamurthy A, Bhatia R, et al. Tumor cell oxidative metabolism as a barrier to PD-1 blockade immunotherapy in melanoma. JCI Insight. 2019 4(5): e124989. A.

Scharping NE, Menk AV, Whetstone RD, Zeng X, Delgoffe GM. Efficacy of PD-1 Blockade Is Potentiated by Metformin-Induced Reduction of Tumor Hypoxia. Cancer Immunol Res. 2017; 5(1):9–16.

291 Dual-specific antibodies blocking both PD-L1 and PD-L2 engagement of PD-1 restore anti-tumor immunity

Background

Inhibition of T cell activation and effector function via engagement of the co-inhibitory receptor PD-1 is a critical mechanism enabling tumors to evade host immunity. The two ligands for PD-1, PD-L1 and PD-L2, can be expressed by a variety of immunosuppressive stromal cells, particularly of the myeloid lineage, endothelial cells, and by tumors themselves. In addition to PD-1, PD-L1 engages B7-1 in an additional co-inhibitory interaction. Blocking only PD-1 or only PD-L1 thus does not relieve all inhibitory components of this pathway. We hypothesized that bispecific antibodies blocking both PD-L1 and PD-L2 could more fully restore tumor-specific T cell activation and potentiate anti-cancer immunotherapy. Furthermore, we speculated that enhancing the cytotoxic effector function of these antibodies might further enhance their efficacy through the depletion of tumor cells and supportive stroma.

Methods

We investigated the capacity of monoclonal antibodies capable of bivalent binding to both PD-L1 and PD-L2 to restore the function of PD-1-suppressed T cells in vitro. To assess the in vivo therapeutic efficiency of bispecific PD-Ligand antibodies with ADCC capacities, mouse IgG2a and modified human IgG1 versions were generated. We assessed their ADCC activity in vitro using a bioluminescent reporter assay, and their therapeutic efficiency in vivo in syngeneic or human-cell derived tumors.

Results

The bispecific antibodies we generated restore the function of PD-1-suppressed T cells in vitro with equivalent efficiency to the FDA approved PD-1 antibody Pembrolizumab. Moreover, our modified human bispecific antibodies lead to significantly higher FcγRIIa activation than FDA-approved clinical human IgG1 PD-L1 antibodies in vitro. In vivo, ADCC-capable PD-Ligand bispecific antibodies suppress the growth of U2940 lymphoma in immunodeficient mice more efficiently than Rituximab, and in a syngeneic model of PD-L1/PD-L2 double positive colon carcinoma, these antibodies demonstrate superiority to PD-1 blocking antibodies to limit tumor growth and increase survival. Furthermore, treatment with our bispecific antibodies increases T cell proliferation and cytotoxicity and reduces density of immunosuppressive myeloid stroma in vivo.

Conclusions

ADCC-capable PD-Ligand bispecific antibodies display higher therapeutic potential than existing anti-PD-1 antibodies and represent a new class of PD-1 pathway therapeutics with significant potential for the treatment of a variety of human cancers.

Acknowledgements

I would like to thank Anupallavi Srinivasamani, PhD student in Michael Curran’s lab, who performed a considerable amount of the work on this project before I joined.

233 Human PD-L2 triggers a unique T cell inhibitory program through PD-1 engagement distinct from that of PD-L1

Background

PD-1/PD-L1 blockade is responsible for the majority of the success of cancer immunotherapy.1 However, only 14% of patients eligible to receive checkpoint blockade achieve objected clinical responses.2 3 The reason for the failure of PD-L1 blockade may be attributed to the recently appreciated widespread expression of PD-L2 across human cancers and its immunosuppresive stromal cells.4 PD-L2 expression was shown to be as or more predictive of response to PD-1 blockade than PD-L14. PD-L2 traditionally was dismissed as functionally redundant to PD-L1 varying only in pattern of expression. We hypothesize that PD-L2 engages PD-1 to generate a distinct inhibitory signal from that of PD-L1, and antibody mediated blockade and depletion of PD-L2+ cells may promote anti-tumor immunity that is superior to PD-L1 blockade alone.

Methods

Cell based bioluminescent assay demonstrated the nature of regulation mediated by human PD-L2 through the PD-1 co-receptor. RNA-sequencing identified key differences in the signaling pathways generated in Jurkat T cells by PD-1 binding to PD-L1 or PD-L2. Multidimensional flow cytometry determined the differential effects of PD-L1 and PD-L2 on human T cell proliferation and effector function. Western blot elucidated the temporal kinetics of inhibition mediated by PD-L1 and PD-L2. Survival studies in murine syngeneic lymphoma model evaluated the efficacy of antibody mediated blockade and depletion of PD-L2+ cells.

Results

We validated that human PD-L2, unlike murine PD-L2, generates a purely co-inhibitory signal in human T cells, albeit with a reduced inhibitory potential relative to PD-L1. We discovered significant differences in downstream T cell signaling pathways generated by PD-L1 versus PD-L2 through PD-1 engagement. Human PD-L1 and PD-L2 differentially modulated T cell effector function and proliferation with PD-L2 preferentially arresting T cells in S-phase of cell cycle. PD-L1 and PD-L2 also differed in the temporal kinetics of dephosphorylation of the membrane proximal proteins in the TCR-CD3 signaling complex. We observed that combination blockade of PD-L1 and PD-L2 improves on blockade of PD-L1 alone resulting in increased production of IL-2 and IFNγ in primary human mixed lymphocyte reactions. Our data in a syngeneic murine model of EL4 showed that effector-function capable PD-L2 blocking antibodies are therapeutically superior to PD-L1 or PD-L2 blockade alone.

Conclusions

We are the first to report on T cell immunoregulatory functions of PD-L2 which are distinct from those of PD-L1, and demonstrate that the more tumor-selective expression pattern of PD-L2 relative to PD-L1 provides a therapeutic advantage to effector-function capable PD-L2 antibodies.

Acknowledgements

AS was supported by the CPRIT Research Training Grant(RP170067)

References

Ribas A, Wolchok JD (2018). Cancer immunotherapy using checkpoint blockade. Science 359:1350–1355.

Cristescu R, Mogg R, Ayers M, Albright A, Murphy E, Yearley J, Sher X, Liu XQ, Lu H, Nebozhyn M, Zhang C, Lunceford JK, Joe A, Cheng J, Webber AL, Ibrahim N, Plimack ER, Ott PA, Seiwert TY, Ribas A, McClanahan TK, Tomassini JE, Loboda A, Kaufman D (2018). Pan-tumor genomic biomarkers for PD-1 checkpoint blockade-based immunotherapy. Science 362.

Haslam A, Prasad V (2019). Estimation of the percentage of US patients with cancer who are eligible for and respond to checkpoint inhibitor immunotherapy drugs. JAMA Netw Open 2:e192535.

Yearley JH, Gibson C, Yu N, Moon C, Murphy E, Juco J, Lunceford J, Cheng J, Chow LQM, Seiwert TY, Handa M, Tomassini JE, McClanahan T (2017). PD-L2 expression in human tumors: relevance to anti-PD-1 therapy in cancer. Clin Cancer Res 23:3158–3167.

758 High-potency synthetic STING agonists rewire the myeloid stroma in the tumour microenvironment to amplify immune checkpoint blockade efficacy in refractory pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies and is clinically unresponsive to immune checkpoint blockade (ICB) immunotherapy.1 2 High densities of immunosuppressive myeloid cells,3 a paucity of antigen-presenting cells4–6 and T cell exclusion from tumour microenvironment7 all contribute to the refractory nature of PDAC to immune-based therapies. We and others have shown that innate immune activation of myeloid stroma via engagement of the STING (Stimulator of Interferon Genes) pathway can mediate proinflammatory remodeling and trigger a flood of T cell infiltration into otherwise 'cold' tumours.8–11 To that end, intratumoral injection of cyclic dinucleotide (CDN) agonists of the STING pathway has been shown to foster local and abscopal tumor immunity.8–10 Despite proven therapeutic efficacy in preclinical models, the mechanistic basis at a cellular level of how CDNs reprogram the suppressive myeloid stroma to sensitise tumours to ICB is poorly understood.

Methods

Using RNA sequencing and protein arrays we profiled myeloid-derived suppressor cell (MDSC) and M2 macrophage function following stimulation with CDNs of ascending potency. We describe the effects of CDN STING agonists on cell cycle dynamics, metabolic reprogramming and c-Myc expression in MDSCs. Next, in an orthotopic Kras+/G12DTP53+/R172HPdx1-Cre (KPC)-derived model of PDAC, we determined the ability of intratumorally-administered CDNs to sensitise PDAC to checkpoint blockade using bioluminescent in vivo imaging and multi-parameter flow cytometry of tumor stroma post-therapy.

Results

Multi-omics profiling of MDSCs and M2 Macrophages of human and murine origin show that high-potency synthetic STING agonists rewire these populations from immunosuppressive to immune-permissive phenotypes in part through inhibition of c-Myc signaling, energy metabolic modulation, and antagonism of cell cycle. Intratumoral injection of the STING agonist, IACS-8803 resulted in an amplified therapeutic response to checkpoint blockade that was dependent on T/NK cell infiltration into the tumour. Furthermore, dimensionality reduction analyses of multiparameter flow cytometry data show proinflammatory remodeling of the myeloid stroma and enhanced T cell function as salient features of synthetic agonists versus natural CDNs in orchestrating the in vivo therapeutic benefit.

Conclusions

This study uncovers molecular and cellular mechanisms by which STING agonists drive proinflammatory conversion of tumour myeloid stroma. We are the first to report that synthetic CDN STING agonists affect MDSC and M2 macrophage repolarization through altering energy metabolism and c-Myc signalling. Lastly, we demonstrate the potential for high-potency STING agonists to overcome resistance to checkpoint blockade in an aggressive orthotopic tumour model of PDAC.

References

Royal RE, Levy C, et al. Phase 2 trial of single agent Ipilimumab (anti-CTLA-4) for locally advanced or metastatic pancreatic adenocarcinoma. J Immunother 2010;33(8):828–33.

Brahmer JR, Tykodi SS, et al. Safety and activity of anti-PD-L1 antibody in patients with advanced cancer. N Engl J Med 2012;366(26):2455–65.

Karakhanova S, Link J. Characterization of myeloid leukocytes and soluble mediators in pancreatic cancer: importance of myeloid-derived suppressor cells. Oncoimmunology 2015;4:e998519.

Dallal RM, Christakos P, et al. Paucity of dendritic cells in pancreatic cancer. Surgery 2002;131:135–138.

Yamamoto T, Yanagimoto H, et al. Circulating myeloid dendritic cells as prognostic factors in patients with pancreatic cancer who have undergone surgical resection. J Surg Res 2012;173:299–308.

Hegde S, Krisnawan V, et al. Dendritic cell paucity leads to dysfunctional immune surveillance in pancreatic cancer. Cancer Cell 2020;37(3):289–307.

Beatty GL, Winograd R, et al. Exclusion of T cells from pancreatic carcinomas in mice is regulated by Ly6Clow F4/80+ extratumoral macrophages. Gastroenterology 2015;149(1):201–210.

Baird JR, Friedman D, et al. Radiotherapy combined with novel STING-Targeting oligonucleotides results in regression of established tumors. Cancer Res 2016;76(1):50–61.

Ager CR, Reilley MJ, et al. Intratumoral STING activation with T-cell checkpoint modulation generates systemic antitumor immunity. Cancer Immunol Res 2017;5(8):676–84.

Smith TT, Moffett HF, et al. Biopolymers codelivering engineered T cells and STING agonists can eliminate heterogeneous tumors. J Clin Invest 2017;127(6):2176–91.

Jing W, McAllister D, et al. STING agonist inflames the pancreatic cancer immune microenvironment and reduces tumor burden in mouse models. J Immunother Cancer 2019;7(1):115.

754 TIGIT-PVR is a key immune checkpoint and therapeutic target in HPV-positive head and neck squamous cell carcinomas

Background

Human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HPV+ HNSCC) is a disease that has moderate response to anti-PD-1/L1 immune checkpoint blockade, with the response rates less than 20% and median progression-free survival less than 3 months. A greater understanding of tumor intrinsic and extrinsic factors that restrict anti-tumor immunity in the tumor immune microenvironment (TIME) is needed to identify other immune checkpoints to enhance therapeutic efficacy.

Methods

Two cohorts (TCGA n=72 and a separate cohort n=84) of surgically resected, treatment-naïve HPV+ HNSCC with RNA-seq were analyzed to understand the immune features. In addition, single-cell RNA-seq and TCR-seq were performed on 18 cases to further delineate the immune molecules' interactions. An immune-competent murine HPV+ HNSCC model was used to preliminarily evaluate the therapeutic efficacy.

Results

In two bulk-sequenced HPV+ HNSCC cohorts, TIGIT ligands PVR and NECTIN2 were found to associate with an epithelial-to-mesenchymal gene expression signature, suppression of IFNα and IFNγ signaling, a stromal-enriched or immune-excluded TIME, and poor survival. Single-cell RNA-seq of over 72,000 cells of HPV+ HNSCC revealed that the PVR/NECTIN ligand TIGIT was highly prevalent in T-cells (34%), significantly higher than PD1- (20%, p<0.01). There is an enrichment of cell-cell interactions mediated by TIGIT-PVR/NECTIN2 in the TIME of HPV+HNSCC versus normal tonsil. TIGIT was the most differentially upregulated immune checkpoint on clonally expanded CD8+T-cells and was abundant on antigen-experienced, tissue-resident memory CD8+T-cell and T-regulatory subsets. TIGIT ligands PVR, NECTIN1, and NECTIN2 were abundant on mature regulatory dendritic cells (DCs), immunosuppressive plasmacytoid (p)DCs, and macrophages, respectively. TIGIT and PD-1 co-blockade in the mEER syngeneic murine model significantly reduced tumor growth, improved survival, restored effector function of HPV16E7-specific CD8+T cells, natural killer cells, and DCs, and conferred tumor re-challenge protection.

Conclusions

TIGIT-PVR/NECTIN receptors/ligands are more abundant than PD-1/L1 in the TIME of HPV+ HNSCC. Co-blockade of TIGIT and PD-1 immune checkpoints enhanced anti-tumor efficacy in a CD8+ T-cell-dependent manner and conferred long-term immune protection in a murine model. Our study nominates TIGIT as a therapeutic target for HPV+ HNSCC.

730 Hypoxia reduction in tandem with anti-angiogenic therapy remodels the PDAC microenvironment and potentiates CD40 agonist therapy

Background

The majority of patients with pancreatic ductal adenocarcinoma (PDAC) fail to derive any durable responses from single agent immune checkpoint blockade therapy. This refractory state originates from PDAC's unique tumor microenvironment that is densely populated by immunosuppressive myeloid cells while excluding most antitumor CD8 T cells.1 In addition, PDAC is highly hypoxic and exhibits poor vascularity, both qualities which further limit antitumor immunity.2 3 We showed that the hypoxia-activated prodrug TH-302 (Evofosfamide) potentiates immunotherapy responses.4 Mechanistically, TH-302 decreases intratumoral hypoxia and initiates normalization of the tumor vasculature. While TH-302 facilitates a cellular remodeling process that diminishes tumor hypoxia, the nature of the vascular remodeling involved remains unknown, as do the downstream consequences for the composition of the tumor microenvironment and responsiveness to immunotherapy. We hypothesized that anti-angiogenic therapy and Evofosfamide might cooperate to normalize tumor vasculature and diminish hypoxia.

Methods

TH-302 and a vascular endothelial growth factor receptor-2 (VEGFR-2) blocking antibody were used to treat several syngeneic murine models, including orthotopic pancreatic cancer and a transplantable model of prostate cancer. Immunofluorescence and flow cytometry were used to assess intratumoral hypoxia, vessel normalization, and tumor immune infiltrate.

Results

We find that anti-VEGFR-2 (DC101) in combination with TH-302 demonstrates a cooperative benefit to combat both orthotopically implanted pancreatic cancer and transplantable prostate cancer. Combination therapy reduces intratumoral hypoxia, leads to pruning of the tumor vasculature, and increases the infiltration of endothelial cells into hypoxic regions. Across models, the combination of DC101 and TH-302 significantly enhance CD8 T cell function and limits their exhausted state. At the same time, tumor associated macrophages exhibit decreased expression of M2-like features. Similar to other anti-angiogenic therapies, combination DC101 and TH-302 leads to an increased frequency of PD-L1 expressing cells. Concurrent anti-PD-1 failed to provide any additional therapeutic benefit, which in part may be due poor CD8 T cell infiltration. Instead, we find that CD40 agonist therapy is improved when combined with TH-302 and DC101.

Conclusions

TH-302 and DC101 utilize unique yet complementary mechanisms to improve the survival of mice challenged with pancreatic or prostate tumors. This combination relieves hypoxia and simultaneously reinvigorates T cell function and reduces macrophage mediated immunosuppression. In this setting, CD40 agonist therapy provides an additive benefit in prolonging mouse survival. Put together, these data indicate that targeted hypoxia reduction with anti-angiogenic therapy remodels the tumor microenvironment and enhances immunotherapy responses in PDAC.

References

Bear AS, Vonderheide RH, O'Hara MH. Challenges and opportunities for pancreatic cancer immunotherapy. Cancer Cell. 2020;38(6):788–802. doi: 10.1016/j.ccell.2020.08.004. Epub 2020 Sep 17. PMID: 32946773; PMCID: PMC7738380.

Koong AC, Mehta VK, Le QT, Fisher GA, Terris DJ, Brown JM, Bastidas AJ, Vierra M. Pancreatic tumors show high levels of hypoxia. Int J Radiat Oncol Biol Phys 2000;48(4):919–22. doi: 10.1016/s0360-3016(00)00803-8. PMID: 11072146.

Olive KP, Jacobetz MA, Davidson CJ, Gopinathan A, McIntyre D, Honess D, Madhu B, Goldgraben MA, Caldwell ME, Allard D, Frese KK, Denicola G, Feig C, Combs C, Winter SP, Ireland-Zecchini H, Reichelt S, Howat WJ, Chang A, Dhara M, Wang L, Rückert F, Grützmann R, Pilarsky C, Izeradjene K, Hingorani SR, Huang P, Davies SE, Plunkett W, Egorin M, Hruban RH, Whitebread N, McGovern K, Adams J, Iacobuzio-Donahue C, Griffiths J, Tuveson DA. Inhibition of Hedgehog signaling enhances delivery of chemotherapy in a mouse model of pancreatic cancer. Science 2009;324(5933):1457–61. doi: 10.1126/science.1171362. Epub 2009 May 21. PMID: 19460966; PMCID: PMC2998180.

Jayaprakash P, Ai M, Liu A, Budhani P, Bartkowiak T, Sheng J, Ager C, Nicholas C, Jaiswal AR, Sun Y, Shah K, Balasubramanyam S, Li N, Wang G, Ning J, Zal A, Zal T, Curran MA. Targeted hypoxia reduction restores T cell infiltration and sensitizes prostate cancer to immunotherapy. J Clin Invest 2018;128(11):5137–5149. doi: 10.1172/JCI96268. Epub 2018 Oct 15. PMID: 30188869; PMCID: PMC6205399.

865 iosH2 exerts potent anti-tumor activity by blocking LILRB1/2 and KIR3DL1 receptor signaling

Background

To develop novel anti-cancer therapeutics we have used a reverse rational approach and searched for human HLA class I molecules known to induce autoimmunity and long-term lasting viral control as a surrogate marker for potential anti-cancer activity. HLA-B*27 or HLA-B*57 are well known genetic factors associated with superior control of viral infections (e.g. HIV and HCV) through processes related to both adaptive and innate immunity. Here we demonstrate that the expression of an optimised HLA-B57-Fc fusion protein (iosH2) exerts anti-tumor efficacy through its multimodal inhibition of LILRB1/2 and KIR3DL1 receptors.

Methods iosH2 was produced by stable expression in CHO cells and purified by standard chromatography techniques. Interaction and competition studies were performed using Bio-Layer Interferometry, ELISA, and cell-based assays. Analysis of LILRB1/2 downstream ITIM signaling was assessed using an automated western blot system. Functional cell-based assays including in vitro polarization and phagocytosis of macrophages, T cell and NK cell assays were assessed using live-cell imaging. In vivo efficacy studies were performed using syngeneic and humanized mouse models of cancer.

Results iosH2 binds with nanomolar affinity to LILRB1/2 and KIR3DL1, and blocks HLA-G and ANGPTL’s binding to LILRB1/2. iosH2 reduces ITIM downstream signalling including phosphorylation of SHP1/2 and promotes conversion from M2 to M1 macrophage phenotype resulting in enhanced tumor cell phagocytosis in vitro. In addition, iosH2 increases T and NK cell cytotoxicity in co-cultures with cancer cell lines. In vivo efficacy studies demonstrate therapeutic efficacy in syngeneic C38 colon cancer mice and in BRGSF-HIS humanized PDX NSCLC mice in concert with reduction of pro-tumorigenic cytokines.

Conclusions iosH2 binds to LILRB1/2 and KIR3DL1, restores immune effector cell function in vitro and demonstrates anti-tumor activity in diverse in vivo mouse models. iosH2 is a first-in-class multi-functional agent that promotes key components of the innate and adaptive immune system leading to profound anti-tumor activity. Clinical development is underway and a phase I trial in preparation.

Ethics Approval

1. Animal housing and experimental procedures were conducted according to the French and European Regulations and the National Research Council Guide for the Care and Use of Laboratory Animals7–8. The animal facility is authorized by the French authorities (Agreement N° B 21 231 011 EA). All animals procedures (including surgery, anesthesia and euthanasia as applicable) used in the current study (200269/ACT1 C38 SC/Ethical protocol: ONCO 1) were submitted to the Institutional Animal Care and Use Committee of Oncodesign (Oncomet) approved by French authorities (CNREEA agreement N° 91). 2. Animal welfare for this study complies with the UK Animals Scientific Procedures Act 1986 (ASPA) in line with Directive 2010/63/EU of the European Parliament and the Council of 22 September 2010 on the protection of animals used for scientific purposes. All experimental data management and reporting procedures were in strict accordance with applicable Crown Bioscience UK Guidelines and Standard Operating Procedures.

763 Intratumoral delivery of high potency STING agonists modulates the immunosuppressive myeloid compartment and induces curative responses in checkpoint-refractory glioblastoma models

Background

Glioblastoma is an aggressive primary brain malignancy that is characterized by a highly suppressive tumor microenvironment, including myeloid-derived suppressor cells, tumor-associated macrophages, and brain-resident microglia, but lacking significant T cell infiltration.1 2 This phenotype is reflected in the recently developed QKi-/- Pten-/- P53-/- (QPP) tumor model,3 which we show is resistant to PD1 or CTLA-4 blockade, but sensitive to agonists of the innate immune sensor Stimulator of Interferon Genes (STING). We have previously shown that agonists of the innate dsDNA-sensing cGAS-STING pathway are capable of proinflammatory repolarization in in vitro models of suppressive myeloid cells, although their function in the context of the Glioblastoma myeloid compartment in vivo remains poorly understood.4

Methods

We utilized the synthetic cyclic di-nucleotide STING agonists IACS-8803 (8803) and ML-RR-S2-CDA (MLRR) to assess survival and tumor immune infiltrate functional reprogramming in two orthotopic transplantable human and murine Glioblastoma tumor models, U87 and the recently developed QPP8 (Qki-/- Pten-/- P53-/-). Using in vitro models of M2-polarized microglia, we investigated the ability of natural (2'3'-cGAMP) and synthetic (MLRR and 8803) STING agonists to reverse immunosuppressive microglial polarization.

Results

We found that intratumoral delivery of STING agonists significantly prolonged survival in the murine QPP8 orthotopic Glioblastoma tumor model, in contrast to checkpoint blockade which had no benefit on survival. In huNOG-EXL mice engrafted with human hematopoietic stem cells implanted with orthotopic U87 Glioblastoma, intratumoral delivery of STING agonists significantly prolonged survival and reduced expression of CD163 and CD206 on human tumor-infiltrating myeloid populations. Preliminary data suggests that in vitro suppressively-polarized microglia reduce expression of M2 functional markers, and increase expression of iNOS, PD-L1, CD80, and CD86 in a STING agonist potency-dependent manner.

Conclusions

We found that STING agonists can induce curative responses in checkpoint-refractory murine Glioblastoma models and mediate significant extension of survival in a humanized mouse U87 xenograft setting. This prolonged survival is associated with a decrease in immunosuppressive M2 functional markers in human tumor infiltrating myeloid populations. Additionally, M2-polarized microglia demonstrated a reduction in M2 functional markers and upregulation of proinflammatory M1 markers following treatment with STING agonists. Together these results indicate that delivery of STING agonists can induce proinflammatory repolarization of the Glioblastoma myeloid stroma, including both infiltrating myeloid populations and brain-resident microglia, to drive prolonged survival in refractory models of Glioblastoma.

References

Gabrusiewicz K, Rodriguez B, Wei J, et al. Glioblastoma-infiltrated innate immune cells resemble M0 macrophage phenotype. JCI Insight 2016;1(2).

Quail DF, Joyce JA. The microenvironmental landscape of brain tumors. Cancer Cell 2017;31(3):326–41.

Shingu T, Ho AL, Yuan L, et al. Qki deficiency maintains stemness of glioma stem cells in suboptimal environment by downregulating endolysosomal degradation. Nat Genet 2017;49(1):75–86.

Ager C, Boda A, Rajapakshe K, et al. (2021) “High potency STING agonists engage unique myeloid pathways to reverse pancreatic cancer immune privilege. JITC (in press)

Ethics Approval

All experiments were conducted according to protocols approved by the University of Texas MD Anderson Cancer Center Institutional Animal Care and Use Committee.

325 Eliminating tumor immune privilege through immune checkpoint cytoreduction

Background

Anti-checkpoint antibodies blocking T cell co-inhibitory molecules (e.g. αPD-1, αCTLA-4) allow immune effector cells to persist, expand, and maintain cytotoxic function in the tumor microenvironment (TME). Despite being effective in immune ”hot” tumors that are infiltrated by effector anti-tumor cells, immune ”cold” tumors fail to respond to checkpoint blockade. ”Cold” tumors are populated with immune suppressive cells including regulatory T cells, M2 macrophages, and myeloid derived suppressor cells, which inhibit immune effector infiltration and function. These suppressive populations, along with tumor cells, express co-inhibitory checkpoints already targeted with current immunotherapeutics, but also some checkpoints in need of further investigation. We hypothesized that by targeting these checkpoints with cytoreductive antibodies which selectively deplete suppressive populations and tumor cells via ADCC/ADCP, we will compromise ”cold” immune privilege and restore an efficient anti-tumor immune response.

Methods

To identify novel targets to produce checkpoint cytoreductive antibodies we conducted in silico analysis that prioritized immune-inhibitory targets with tumor-specific or tumor-selective expression on cell surface. We cross-referenced a previously published list of transmembrane proteins against publicly sourced datasets including TCGA, HPA, GTEx, BioGPS, and SAGE.1 We then characterized the expression profile of each selected target on tumor cells in vitro and on cell populations in the TME ex vivo via multiparameter flow cytometry. Finally, we assessed the impact of existing checkpoint-targeting cytoreductive antibodies on survival and tumor growth in murine ”hot” and ”cold” tumors.

Results

VISTA and DLL3 were identified via in silico analysis as co-inhibitory surface proteins specifically and selectively in the TME and not in healthy tissues. DLL3 is mainly expressed on tumor cells while VISTA was described mostly on immunosuppressive myeloid cells. An anti-DLL3 antibody was produced by a previous laboratory as an IgG1 antibody, and we engineered a version in the depletive (IgG2a) isotype, which will enable us to target this checkpoint with either a blocking or a depleting antibody. Flow cytometry analysis identified VISTA on multiple myeloid cell populations in ”cold” 4T1 murine mammary tumors while its expression was low in spleen. To start assessing the efficiency of depleting versus non-depleting antibodies, ”hot” CT26 murine tumors and 4T1 tumors were treated with an αCTLA-4-IgG2a or αCTLA-4-IgG1. Groups treated with depleting antibodies showed increased survival compared to groups treated with non-depleting antibodies.

Conclusions

Novel immune-inhibitory checkpoints can be identified and targeting them with cytoreductive antibodies leads to a higher anti-tumor immune response. This investigation opens the door to more efficient combination therapies.

Acknowledgements

Supported by a training fellowship from The University of Texas Health Science Center at Houston Center for Clinical and Translational Sciences TL1 Program (Grant No. TL1 TR003169).

References

Wang J, et al. Siglec-15 as an immune suppressor and potential target for normalization cancer immunotherapy. Nat Med 25,(2019).

Mycobacterium porcinum Skin and Soft Tissue Infections After Vaccinations - Indiana, Kentucky, and Ohio, September 2018-February 2019

During December 2018-February 2019, a multistate investigation identified 101 patients with vaccination-associated adverse events among an estimated 940 persons in Kentucky, Indiana, and Ohio who had received influenza; hepatitis A; pneumococcal; or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines at the workplace during September 11-November 28, 2018. These vaccines had been administered by staff members of a third-party health care company contracted by 24 businesses. Company A provided multiple vaccine types during workplace vaccination events across 54 locations in these adjoining states. Injection-site wound isolates from patients yielded Mycobacterium porcinum, a nontuberculous mycobacteria (NTM) species in the Mycobacterium fortuitum group; subtyping using pulsed-field gel electrophoresis of all 28 available isolates identified two closely related clusters. Site visits to company A and interviews with staff members identified inadequate hand hygiene, improper vaccine storage and handling, lack of appropriate medical record documentation, and lack of reporting to the Vaccine Adverse Event Reporting System (VAERS). Vaccination-associated adverse events can be prevented by training health care workers responsible for handling or administering vaccines in safe vaccine handling, administration, and storage practices, timely reporting of any suspected vaccination-associated adverse events to VAERS, and notifying public health authorities of any adverse event clusters.

Abstract 1553: Intratumoral delivery of STING agonist results in radiographic response in spontaneous canine high-grade glioma

Introduction: STING (stimulator of interferon genes) agonists can increase T cell infiltration into immunologically “cold” tumors such as gliomas through proinflammatory activation of suppressive tumor stroma, re-education of tumor-supportive M2 macrophages toward a proinflammatory M1 phenotype and can reverse the suppressive phenotype of myeloid-derived suppressor cells. Preclinical murine glioma models have not correlated with immunotherapy responses in human glioma subjects in part because of poor correlative immunobiology, but recent “omic” profiling has demonstrated a marked association of spontaneously arising canine gliomas with those in human subjects.

Methods: We have created a novel STING agonist IACS-8779 that has shown robust activation of the STING pathway with equivalent or superior systemic anti-tumor responses relative to clinical benchmark compounds in murine models. A dose escalation clinical trial was conducted in client-owned canines (n=4) with newly-diagnosed presumed high-grade glioma identified radiographically on standard MRI sequences obtained on a 3T magnet. Each dog received 2 injections intratumorally at an interval of 4-6 weeks. The dose of IACS-8779 was sequentially increased over the course of the 6 injections from 5ug to 20ug, whereas the injection volume was fixed at 50uL. Injections were targeted to the tumors by image guidance, and injections were performed at a rate of 2uL/minute. Neurological status was monitored during the inter-injection interval. MRI was repeated at intervals of 4-6 weeks and radiographic responses were volumetrically analyzed.

Results: All dogs tolerated the injections well with clinical symptoms remaining stable between the first and second injection. The survival times of the first 2 dogs were 2.5 and 9 months from the date of onset of signs, whereas the remaining dogs are still alive. The first dog, treated twice at a dose of 5ug, had progressive disease on serial MRI; whereas the second (5 and 10ug) and third (15 and 20ug) dogs had stable disease. The fourth dog treated at 20ug showed a volumetric change of 0.785cm3 pre-treatment to 0.194cm3 (&gt;75%) after a single dose 5 weeks after the first injection.

Conclusion: In support of previously published data showing effectiveness of IACS-8779 for treatment of orthotopic murine tumors (Ager CR, Bioorg Med Chem Lett. 2019), these data indicate that IACS-8779 is well-tolerated for repeated intratumoral injections up to 20ug in 50uL in a large animals (canines) with spontaneous glioma. Further, we have shown that a single injection of 20ug IACS-8779 can produce a radiographic response in a spontaneously arising high-grade glioma in the dog.

Citation Format: C. Elizabeth Boudreau, Cynthia Kassab, Martina Ott, Chase M. DeRay, Jonathan Levine, Michael Curran, Amy B. Heimberger. Intratumoral delivery of STING agonist results in radiographic response in spontaneous canine high-grade glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1553.

External stakeholder management and engagement on urban construction projects in Ireland

The disruptive nature of urban construction projects results in hazardous and complex environments, particularly when considering the management of external stakeholders. Therefore, this paper aims to identify who these external stakeholders are, what issues occur and what strategies are used to counteract such issues on urban construction projects in Ireland. The research method is qualitatively based, encompassing five exploratory case study interviews with five construction professionals on urban construction projects in Ireland. The data are qualitatively assessed using mind-mapping software and cognitively summarised. The research identifies ‘residents’, ‘road users’, ‘environmental agencies’ and the ‘local authority’ as the main external stakeholders, from a potential list of 22. ‘Traffic management’, ‘noise’, ‘dust and vibrations from site works’, ‘excess documentation’ and ‘environmental controls’ were identified as the main issues, from a list of 26 issues. Finally, ‘consultations’, ‘regular meetings’, ‘traffic-management systems’, ‘inform stakeholders early’, ‘noise-monitoring reports’ and ‘sustainable construction methods’ were identified as the main response strategies, from a list of 15 potential strategies. The key contribution of this study illustrates to on-site management the importance of identifying and engaging with the external stakeholders, in addressing their issues and, subsequently, counteracting such concerns using one or more response strategies identified.

Chasing ghosts: An investigation of the ghosting phenomenon in footprints

Ghosting is a phenomenon that has been identified in dynamic (walking) footprints. There is sparse research on the occurrence of ghosting; however, due to the forensic value of footprints and their use in other scientific fields, the phenomenon of ghosting warrants further study. Ghosting can be used to determine if a footprint is static (standing) or dynamic, which can help forensic investigators create a sequence of events at a crime scene. Furthermore, this can help in footprint comparisons from this determination, as "like versus like" comparisons of dynamic or static footprints can be made. The purpose of this research was to determine the prevalence and locations of the ghosting phenomena in dynamic footprints. 136 dynamic footprints from 68 volunteers were collected using an inkless collection system. Each footprint was visually inspected for ghosting as well as examined using software. Ghosting was present on at least one location in all footprints. The highest prevalence occurred at the tip of the great toe, followed by the second digit and the heel. To a lesser extent, ghosting appeared at the tips of the other three digits. Ghosting often occurred at two or more areas in a given footprint.

Anti-PD-1 Induces M1 Polarization in the Glioma Microenvironment and Exerts Therapeutic Efficacy in the Absence of CD8 Cytotoxic T Cells

PURPOSE

Anti-programmed cell death protein 1 (PD-1) therapy has demonstrated inconsistent therapeutic results in patients with glioblastoma (GBM) including those with profound impairments in CD8 T-cell effector responses.

EXPERIMENTAL DESIGN

We ablated the CD8α gene in BL6 mice and intercrossed them with Ntv-a mice to determine how CD8 T cells affect malignant progression in forming endogenous gliomas. Tumor-bearing mice were treated with PD-1 to determine the efficacy of this treatment in the absence of T cells. The tumor microenvironment of treated and control mice was analyzed by IHC and FACS.

RESULTS

We observed a survival benefit in immunocompetent mice with endogenously arising intracranial glioblastomas after intravenous administration of anti-PD-1. The therapeutic effect of PD-1 administration persisted in mice even after genetic ablation of the CD8 gene (CD8^-/-). CD11b⁺ and Iba1⁺ monocytes and macrophages were enriched in the glioma microenvironment of the CD8^-/- mice. The macrophages and microglia assumed a proinflammatory M1 response signature in the setting of anti-PD-1 blockade through the elimination of PD-1-expressing macrophages and microglia in the tumor microenvironment. Anti-PD-1 can inhibit the proliferation of and induce apoptosis of microglia through antibody-dependent cellular cytotoxicity, as fluorescently labeled anti-PD-1 was shown to gain direct access to the glioma microenvironment.

CONCLUSIONS

Our results show that the therapeutic effect of anti-PD-1 blockade in GBM may be mediated by the innate immune system, rather than by CD8 T cells. Anti-PD-1 immunologically modulates innate immunity in the glioma microenvironment-likely a key mode of activity.

The mobilisation of early mature CD56dim-CD16bright NK cells is blunted following a single bout of vigorous intensity exercise in Type 1 Diabetes

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease that targets and destroys insulin-secreting pancreatic beta cells. Although T cell mediated, a number of other immune cells are also critically involved in coordinating the events leading to T1D. Specifically, innate subsets play an important role in the pathogenesis of T1D. NK cells are one of the first cell types to infiltrate the pancreas, causing damage and release of beta cell antigens. Previous work in our group has shown differential mobilisation of highly differentiated CD8+ T cells during vigorous intensity exercise in T1D compared to a control cohort. Here, we aimed to explore exercise-induced mobilisation of other cell types involved in T1D pathogenesis. In this study, we investigated the effects of a single bout of vigorous (80% predicted VO2max) intensity exercise on innate cell mobilisation in T1D and control participants. T1D (N=12, mean age 33.2yrs, predicted VO₂max 32.2 ml.kg.min⁻¹, BMI 25.3 kg.m⁻²) and control (N=12, mean age 29.4yrs, predicted VO2 max 38.5 ml.kg.min⁻¹, BMI 23.7 kg.m⁻² male participants completed a 30-minute bout of cycling at 80% predicted VO₂ max in a fasted state. Peripheral blood was collected at baseline, immediately post-exercise, and 1 hour post-exercise. NK cell subsets mobilised during vigorous intensity exercise in both control and T1D participants. However, mature NK cells, defined as the CD56dimCD16bright subset, displayed a lower percentage increase following vigorous intensity exercise in T1D participants (Control: 185.12%, T1D: 97.06%). This blunted mobilisation was specific to early mature NK cells (KIR+) but not later differentiated NK cells (KIR+CD57+). Myeloid lineage subsets mobilised to a similar extent in both control and T1D participants. In conclusion, vigorous exercise mobilises innate immune cells in people with T1D albeit to a different extent to those without T1D. This mobilisation of innate immune cells provides a mechanistic argument to support exercise in people with T1D where it has the potential to improve surveillance for infection and to modulate the autoimmune response to the beta cell.

Combining Immune Checkpoint Blockade and Tumor-Specific Vaccine for Patients With Incurable Human Papillomavirus 16-Related Cancer: A Phase 2 Clinical Trial

Importance

In recurrent human papilloma virus (HPV)-driven cancer, immune checkpoint blockade with anti-programmed cell death 1 (PD-1) antibodies produces tumor regression in only a minority of patients. Therapeutic HPV vaccines have produced strong immune responses to HPV-16, but vaccination alone has been ineffective for invasive cancer.

Objective

To determine whether the efficacy of nivolumab, an anti-PD-1 immune checkpoint antibody, is amplified through treatment with ISA 101, a synthetic long-peptide HPV-16 vaccine inducing HPV-specific T cells, in patients with incurable HPV-16-positive cancer.

Design, Setting, and Participants

In this single-arm, single-center phase 2 clinical trial, 24 patients with incurable HPV-16-positive cancer were enrolled from December 23, 2015, to December 12, 2016. Duration of follow-up for censored patients was 12.2 months through August 31, 2017.

Interventions

The vaccine ISA101, 100 μg/peptide, was given subcutaneously on days 1, 22, and 50. Nivolumab, 3 mg/kg, was given intravenously every 2 weeks beginning day 8 for up to 1 year.

Main Outcomes and Measures

Assessment of efficacy reflected in the overall response rate (per Response Evaluation Criteria in Solid Tumors, version 1.1).

Results

Of the 24 patients (4 women and 20 men; 22 with oropharyngeal cancer; median age, 60 years [range, 36-73 years]), the overall response rate was 33% (8 patients; 90% CI, 19%-50%). Median duration of response was 10.3 months (95% CI, 10.3 months to inestimable). Five of 8 patients remain in response. Median progression-free survival was 2.7 months (95% CI, 2.5-9.4 months). Median overall survival was 17.5 months (95% CI, 17.5 months to inestimable). Grades 3 to 4 toxicity occurred in 2 patients (asymptomatic grade 3 transaminase level elevation in 1 patient and grade 4 lipase elevation in 1 patient), requiring discontinuation of nivolumab therapy.

Conclusions and Relevance

The overall response rate of 33% and median overall survival of 17.5 months is promising compared with PD-1 inhibition alone in similar patients. A randomized clinical trial to confirm the contribution of HPV-16 vaccination to tumoricidal effects of PD-1 inhibition is warranted for further study.

Trial Registration

ClinicalTrials.gov identifier: NCT02426892.

IMMU-10. ESTABLISHING EFFECTIVE MODELS FOR IMMUNOTHERAPY IN GBM

The introduction of immunotherapies has been paradigm shifting for cancers that were previously a death sentence. However, preclinical/clinical studies on glioblastoma (GBM) have generated mixed outcomes in patients, likely due to its great heterogeneity of immune microenvironment, particularly the myeloid cell populations. Primary patient studies have been limited by a difficulty in performing longitudinal studies, uncontrolled environmental conditions, and genetic variability. There is also, unfortunately, a paucity of mouse models that effectively re-capitulate the immune microenvironment of the human disease. To address these difficulties, we have established the Qk/p53/Pten (QPP) triple knockout mouse model established in our lab. The QPP model uses a cre-lox system to induce Qk deletion on a Pten−/−; p53−/− background which helps NSCs maintain their stemness outside the SVZ in Nes-CreERT2;QkiL/L PtenL/L p53L/L mice, which develops glioblastoma with survival of ~105 days. We have preliminarily assessed the QPP tumors as a faithful model to study the immune response to GBM and found them to recapitulate human GBM with respect to differential response to checkpoint blockade therapy and myeloid and T-cells histopathologically, particularly regarding upregulation of Arginase-1 (Arg1). Arg1 is the canonical marker for tumor-associated macrophages (TAMs), which is a major population of myeloid cells that greatly infiltrate in human GBM, sometimes making up more than ~30% of all GBM cells. Given TAMs’ prevalence in the tumor microenvironment and their upregulation of Arg1 in both human GBM and our QPP model, we are testing whether manipulation of Arg1 will impact TAM function and influence GBM growth. We are also evaluating arginine metabolism in TAMs effect on T cell function in GBM. Lastly, we have developed a genetically engineered mouse model to study the role of Arg1 knockout in a GBM context in-vivo. Our studies suggest that Arg1 plays an important role in GBM immune interaction.

Evaluating steady-state resting energy expenditure using indirect calorimetry in adults with overweight and obesity

BACKGROUND

Determining a period of steady state (SS) is recommended when estimating resting energy expenditure (REE) using a metabolic cart. However, this practice may be unnecessarily burdensome and time-consuming in the research setting.

AIM

The aim of the study was to evaluate the use of SS criteria, and compare it to alternative approaches in adults with overweight and obesity.

METHODS

In this cross-sectional, ancillary analysis, participants enrolled in a bariatric (study 1; n = 13) and lifestyle (study 2; n = 51) weight loss intervention were included. Indirect calorimetry was performed during baseline measurements using a metabolic cart for 25 min, including a 5-min stabilization period at the start. SS was defined as the first 5-min period with a coefficient of variation (CV) ≤10% for both VO₂ and VCO₂ (hereafter REE_5-SS). Body composition was measured using bioelectrical impedance analysis in study 2 participants only. REE_5-SS was compared against the lowest CV (REE_CV-lowest), 5-min time intervals (REE_6-10, REE_11-15, REE_16-20, REE_21-25), 4-min and 3-min SS intervals (REE_4-SS and REE_3-SS), and time intervals of 6-15, 6-20 and 6-25 min (REE_6-15, REE_6-20, and REE_6-25) using repeated measures ANOVA and Bland-Altman analysis to test for bias, limits of agreement and accuracy (±6% measured REE).

RESULTS

Participants were 54 ± 13 years old, mostly women (75%) and had a BMI of 35 ± 5 kg/m². Overall, 54/63 (84%) of participants reached REE_5-SS, often (47/54, 87%) within the first 10-min (6-15 min). Alternative approaches to estimating REE had a relatively low bias (-16 to 13 kcals), narrow limits of agreement and high accuracy (83-98%) when compared to REE_5-SS, in particular, outperforming standard prediction equations (e.g., Mifflin St. Joer).

CONCLUSION

Indirect calorimetry measurements that utilize the 5-min SS approach to estimate REE are considered the gold-standard. Under circumstances of non-SS, it appears 4-min and 3-min SS periods, or fixed time intervals of atleast 5 min are accurate and practical alternatives for estimating REE in adults with overweight and obesity. However, future trials should validate alternative methods in similar populations to confirm these findings.

A comparison of the length and width of static inked two-dimensional bare footprints found on a hard compared to a soft surface

In forensic intelligence-gathering it would be useful to evaluate if there are differences between static inked bare footprints captured on hard surfaces compared to soft surfaces. This was undertaken using samples from 30 undergraduate students. Initially a static footprint was taken for each participant on a hard surface and this was followed by a static footprint on a soft surface. On both occasions, the participants stood on an inkless mat and then on reactive paper, creating a two-dimensional print. The Reel method was used to analyse each footprint and the print was measured to see whether a difference existed between length and width (forefoot and rearfoot width) on a hard surface compared to a soft surface. The conclusion from this study was there is a statistically significant increase in length and width of a static bare footprint on a soft surface as opposed to a hard surface. If a forensic footprint examiner compares static bare footprints found on a soft surface and compares them to a static bare footprint of the same foot taken later, then the increase in both length and width of the footprints on a soft surface should be considered in the evaluation.

Abstract 4799: Inhibition of STAT3 in pancreatic ductal adenocarcinoma and immunotherapeutic implications

Introduction: Signal Transducer and Activators of Transcription 3 (STAT3) plays a pivotal role in carcinogenesis, chemo- and radio-sensitivity, metastasis and immune evasion in multiple malignances including Pancreatic Ductal Adenocarcinoma (PDAC). Our drug discovery program focused on modulators of transcriptional activity led us to identify small molecules that potently inhibits tyrosine 705 phosphorylated STAT3 (p-STAT3). Compound WP1066, currently being evaluated in a Phase I clinical trial (NCT01904123) as orally administered agent and its novel, analog WP1732 suitable for IV administration, were selected as promising, potent p-STAT3 inhibitors with drug-like properties for further development as lead compounds. The purpose of these study is to perform a preclinical evaluation of WP1066 and WP1732 aiming at their future application for treatment of PDAC.

Materials and Methods: The chemical synthesis of WP1066 and WP1732 and their characterization was performed at UT MD Anderson Cancer Center. In vitro efficacy of both inhibitors was assessed using proliferation and apoptosis induction assays in a panel of patient-derived and commercially-available PDAC cell lines. Inhibition of p-STAT3 was investigated using western blot (WB) and immunofluorescence. Acute and multiple dose toxicity of WP1732 was tested in CD-1 mice. Pharmacokinetic parameters of WP1732 after intravenous administration was evaluated in naïve CD-1 mice using Mass Spectrometry LC/MS/MS or rats by liquid scintillation counting (LSC) using radio-labeled agent. Efficacy of both agents alone or in combination with immune checkpoints inhibitors was tested in PDAC tumor models.

Results: Both WP1066 and WP1732 were shown to induce apoptosis and inhibit p-STAT3 and its nuclear localization in all tested PDAC cell lines. Observed IC50 values ranged from 0.5 to 2 µM. WP1732 was well tolerated by mice (LD50 85 mg/kg given IV). Pharmacokinetic and biodistribution studies indicate high plasma levels of the drug and significant accumulation of WP1732 in the pancreas of mice and rats after a single bolus injection of the drug. Importantly, both agents show in vivo efficacy in preliminary experiments when tested alone or in combination with T cell immune checkpoint inhibitors.

Conclusion: WP1066 and WP1732 are inhibitors of p-STAT3 with demonstrated in vitro and in vivo activity against PDAC tumor models. Our preliminary data warrant the further pre-clinical and clinical evaluation of these oncology agents alone and in combination with immunotherapy as a promising new therapeutics for pancreatic cancer.

Citation Format: Rafal Zielinski, Izabela Fokt, Stanislaw Skora, Edward Felix, Krzysztof Grela, Jayakumar Arumugam, Radj Venugopal, Midan Ai, Genevieve Hartley, Michael Curran, Waldemar Priebe. Inhibition of STAT3 in pancreatic ductal adenocarcinoma and immunotherapeutic implications [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 4799.

Abstract 5011: Targeting hypoxia-induced immune suppression to overcome immunotherapy resistance in prostate cancer

Immune checkpoint blockade is effective in “hot” tumors like melanoma with pre-existing immune infiltrates; however, “cold” tumors like prostate cancer fail to respond. We found that prostate cancers harbor regions of hypoxia that resist T cell infiltration even in the context of anti-CTLA-4 (cytotoxic T lymphocyte associated protein-4) and anti-PD-1 (programmed cell death protein 1) blockade. These hypoxic zones serve as islands of immune privilege through the recruitment and suppressive polarization of immature myeloid cells into myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAM). We found that targeted hypoxia ablation using TH-302, a hypoxia-activated prodrug, sensitized both transplantable and spontaneous models of prostate cancer to checkpoint blockade, coincident with enhanced T cell infiltration and effector function and loss of MDSC recruitment and suppressive function. Tumors treated with the combination of TH-302 and checkpoint blockade showed a reduced capacity to suppressively polarize new myeloid immigrants, implying a durable reconditioning of the tumor microenvironment (TME) into an immune-infiltrated, pro-inflammatory milieu. T cells infiltrating combination-treated tumors exhibited increased mitochondrial respiration, consistent with creation of a metabolically favorable milieu for T cell function. Based on these findings, we hypothesized that other approaches capable of metabolically rewiring the TME should promote anti-tumor immunity and sensitize checkpoint blockade-resistant tumors to immunotherapy. With this in mind, we performed a longitudinal study comparing a panel of different mitochondrial respiration inhibitors and a glutaminase inhibitor for their efficacy in reducing hypoxia, improving T cell infiltration and decreasing myeloid cell recruitment and suppressive polarization using immunofluorescence staining and confocal microscopy. Our preliminary data suggests that inhibitors targeting mitochondrial respiration, rather than those targeting glutamine metabolism synergize with checkpoint blockade and exhibit the highest efficacy in increasing T cell recruitment. We continue to characterize the dynamics of hypoxia reduction, duration of normalization following drug withdrawal, and impact on the immune microenvironment of these diverse approaches to metabolic reconditioning.

Citation Format: Priyamvada Jayaprakash, Midan Ai, Arthur Liu, Pratha Budhani, Todd Bartkowiak, Jie Sheng, Casey Ager, Courtney Nicholas, Ashvin Jaiswal, Yanqiu Sun, Krishna Shah, Sadhana Balasubramanyam, Nan Li, Guocan Wang, Jing Ning, Anna Zal, Tomasz Zal, Michael Curran. Targeting hypoxia-induced immune suppression to overcome immunotherapy resistance in prostate 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 5011.

PD-L2 generates a signal through the PD-1 co-receptor distinct from that of PD-L1

Immune checkpoint blockade of the PD-1/PD-L1/PD-L2 signalling axis yields potent anti-tumor responses by disinhibiting T cell effector function. Mouse and human data demonstrating an inhibitory role for PD-L1 has resulted in FDA approval of anti-PD-L1 antibodies; however, PD-L2 remains sparsely studied despite being the higher affinity of the two ligands for PD-1. Recent findings demonstrate that PD-L2 is widely expressed by human malignancies. PD-L1 and PD-L2 have also been shown to induce distinct conformational changes on engaging human PD-1.

We utilized a Jurkat T cell based bioluminescent assay of T cell activation and PD-1 inhibition to determine the unique mechanism of action of human PD-L2. In this system, human PD-L2 generates a solely co-inhibitory signal, but at reduced inhibitory potential relative to PD-L1. We find that unlike murine PD-L2, human PD-L2 appears to have a dedicated co-inhibitory function as we find no significant engagement of the human homolog of its murine co-stimulatory partner RGMb. Reverse phase protein array analysis of human PD-L1 and PD-L2 engagement of PD-1 on Jurkat T cells revealed significant differences in downstream T cell signalling generated by each ligand. We also find that human PD-L1 and PD-L2 have disparate impacts on proliferation wherein PD-L2 supports a preferential arrest of T cells in the S-phase of the cell cycle. We observed that combination blockade of PD-L1 and PD-L2 improves on the blockade of PD-L1 alone resulting in increased production of IL-2 and IFNγ in primary human mixed lymphocyte reactions. Our findings address critical gaps in our knowledge about the basic function of PD-L2 and will inform future attempts to manipulate the PD-1 co-inhibitory circuit.

Practice-based differences in paediatric discoid lupus erythematosus

BACKGROUND

Children with discoid lupus erythematosus (DLE) are at risk for disfigurement and progression to systemic lupus erythematosus (SLE). Consensus is lacking regarding optimal care for children with DLE.

OBJECTIVES

The aim of this study was to compare practice patterns among paediatric dermatologists/rheumatologists treating paediatric DLE.

METHODS

An online survey was sent to 292 paediatric rheumatologists in the Childhood Arthritis and Rheumatology Research Alliance and 200 paediatric dermatologists in the Pediatric Dermatology Research Alliance. Consensus was defined as ≥ 70% agreement.

RESULTS

Survey response rates were 38% (76 of 200) for dermatology and 21% (60 of 292) for rheumatology. Both specialties agreed that screening labs should include complete blood counts with differential, urinalysis, complement levels, erythrocyte sedimentation rate, antinuclear antibody and other autoantibodies, hepatic function and renal function/electrolytes. Both specialties agreed that arthritis or nephritis should prompt intensified evaluation for SLE. No other patient features achieved consensus as disease-modifying risk factors. Hydroxychloroquine was agreed upon as first-line systemic therapy, but consensus was lacking for second- or third-line treatment.

CONCLUSIONS

We found few areas of consensus and significant practice differences between paediatric dermatologists and rheumatologists treating DLE. Knowledge gaps include risk factors for SLE, optimal screening and treatment of refractory skin disease.

A serological marker of the N-terminal neoepitope generated during LOXL2 maturation is elevated in patients with cancer or idiopathic pulmonary fibrosis

Objectives

Lysyl oxidase like 2 (LOXL2) is associated with poor prognosis in idiopathic pulmonary disease (IPF) and cancer. We developed an Enzyme-linked immunosorbent assay (ELISA) targeting the LOXL2 neo-epitope generated through the release of the signal peptide during LOXL2 maturation.

Design and methods

An ELISA targeting the N-terminal site of the human LOXL2 was developed including technical optimization and validation steps. Serum LOXL2 was measured in patients with breast, colorectal, lung, ovarian, pancreatic and prostate cancer, melanoma, IPF and in healthy controls (n = 16).

Results

A technically robust and specific assay was developed. LOXL2 was detectable in serum from healthy controls and showed reactivity towards recombinant LOXL2. Compared to controls, LOXL2 levels were significantly (p < 0.001–0.05) elevated in serum from patients with breast, colerectal, lung, ovarian and pancreatic cancer (mean range: 49–84 ng/mL), but not in prostate cancer (mean: 36 ng/mL) and malignant melanoma patients (41 ng/mL). Serum LOXL2 was elevated in IPF patients compared to healthy controls (mean: 76.5 vs 46.8 ng/mL; p > 0.001)

Conclusions

A specific ELISA towards the N-terminal neo-epitope site in LOXL2 was developed which detected significantly elevated serum levels from patients with above-mentioned cancer types or IPF compared to healthy controls.

STAT3 antisense oligonucleotide AZD9150 in a subset of patients with heavily pretreated lymphoma: results of a phase 1b trial

Background

The Janus kinase (JAK) and signal transduction and activation of transcription (STAT) signaling pathway is an attractive target in multiple cancers. Activation of the JAK-STAT pathway is important in both tumorigenesis and activation of immune responses. In diffuse large B-cell lymphoma (DLBCL), the transcription factor STAT3 has been associated with aggressive disease phenotype and worse overall survival. While multiple therapies inhibit upstream signaling, there has been limited success in selectively targeting STAT3 in patients. Antisense oligonucleotides (ASOs) represent a compelling therapeutic approach to target difficult to drug proteins such as STAT3 through of mRNA targeting. We report the evaluation of a next generation STAT3 ASO (AZD9150) in a non-Hodgkin’s lymphoma population, primarily consisting of patients with DLBCL.

Methods

Patients with relapsed or treatment refractory lymphoma were enrolled in this expansion cohort. AZD9150 was administered at 2 mg/kg and the 3 mg/kg (MTD determined by escalation cohort) dose levels with initial loading doses in the first week on days 1, 3, and 5 followed by weekly dosing. Patients were eligible to remain on therapy until unacceptable toxicity or progression. Blood was collected pre- and post-treatment for analysis of peripheral immune cells.

Results

Thirty patients were enrolled, 10 at 2 mg/kg and 20 at 3 mg/kg dose levels. Twenty-seven patients had DLBCL. AZD9150 was safe and well tolerated at both doses. Common drug-related adverse events included transaminitis, fatigue, and thrombocytopenia. The 3 mg/kg dose level is the recommended phase 2 dose. All responses were seen among DLBCL patients, including 2 complete responses with median duration of response 10.7 months and 2 partial responses. Peripheral blood cell analysis of three patients without a clinical response to therapy revealed a relative increase in proportion of macrophages, CD4+, and CD8+ T cells; this trend did not reach statistical significance.

Conclusions

AZD9150 was well tolerated and demonstrated efficacy in a subset of heavily pretreated patients with DLBCL. Studies in combination with checkpoint immunotherapies are ongoing.

Trial registration

Registered at ClinicalTrials.gov: NCT01563302. First submitted 2/13/2012.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0436-5) contains supplementary material, which is available to authorized users.

Forest restoration: a global dataset for biodiversity and vegetation structure

Restoration initiatives are becoming increasingly applied around the world. Billions of dollars have been spent on ecological restoration research and initiatives, but restoration outcomes differ widely among these initiatives in part due to variable socioeconomic and ecological contexts. Here, we present the most comprehensive dataset gathered to date on forest restoration. It encompasses 269 primary studies across 221 study landscapes in 53 countries and contains 4,645 quantitative comparisons between reference ecosystems (e.g., old-growth forest) and degraded or restored ecosystems for five taxonomic groups (mammals, birds, invertebrates, herpetofauna, and plants) and five measures of vegetation structure reflecting different ecological processes (cover, density, height, biomass, and litter). We selected studies that (1) were conducted in forest ecosystems; (2) had multiple replicate sampling sites to measure indicators of biodiversity and/or vegetation structure in reference and restored and/or degraded ecosystems; and (3) used less-disturbed forests as a reference to the ecosystem under study. We recorded (1) latitude and longitude; (2) study year; (3) country; (4) biogeographic realm; (5) past disturbance type; (6) current disturbance type; (7) forest conversion class; (8) restoration activity; (9) time that a system has been disturbed; (10) time elapsed since restoration started; (11) ecological metric used to assess biodiversity; and (12) quantitative value of the ecological metric of biodiversity and/or vegetation structure for reference and restored and/or degraded ecosystems. These were the most common data available in the selected studies. We also estimated forest cover and configuration in each study landscape using a recently developed 1 km consensus land cover dataset. We measured forest configuration as the (1) mean size of all forest patches; (2) size of the largest forest patch; and (3) edge:area ratio of forest patches. Global analyses of the factors influencing ecological restoration success at both the local and landscape scale are urgently needed to guide restoration initiatives and to further develop restoration knowledge in a topic area of much contemporary interest.

Biodiversity Recovery and Transformation Impacts for Wetland Biodiversity

Life Cycle Assessment (LCA) methods for land use take both occupation and transformation impacts into account. However, for wetlands and impacts from water consumption, it is so far not possible to account for transformation impacts. It is our goal to close this research gap, by determining wetland recovery times and developing characterization factors for transformation. To do this, we conducted a meta-analysis of 59 studies analyzing biodiversity recovery in wetlands subject to passive and active restoration. Generalized linear models were fitted to the biodiversity data and age, along with other wetland characteristics (such as elevation, latitude, or climate class), and were used as predictor variables. The results indicate that elevation, latitude, type of wetland, and restoration method have the strongest effect on recovery speed. Recovery times vary from less than one year to a maximum of 10⁷ years with passive restoration and 10⁵ years with active restoration. Corresponding transformation characterization factors vary between 10^-14 and 10^-2 species-eq·year²/m³. Finally, recognizing the relevance of this work to real-world policy issues beyond LCA, we discuss the implications of our estimated restoration times on the feasibility of "biodiversity offsetting". Offsetting utilizes restoration to replace biodiversity value lost due to development impacts. Our work can help stakeholders make informed decisions on whether offsetting represents a legitimate policy option in a particular context.

Exercise to preserve β-cell function in recent-onset Type 1 diabetes mellitus (EXTOD) - a randomized controlled pilot trial

AIM

Residual β-cell function is present at the time of diagnosis with Type 1 diabetes. Preserving this β-cell function reduces complications. We hypothesized that exercise preserves β-cell function in Type 1 diabetes and undertook a pilot trial to address the key uncertainties in designing a definitive trial to test this hypothesis.

METHODS

A randomized controlled pilot trial in adults aged 16-60 years diagnosed with Type 1 diabetes within the previous 3 months was undertaken. Participants were assigned to control (usual care) or intervention (exercise consultation every month), in a 1 : 1 ratio for 12 months. The primary outcomes were recruitment rate, drop out, exercise adherence [weeks with ≥ 150 min of self-reported moderate to vigorous physical activity (MVPA)], and exercise uptake in the control group. The secondary outcomes were differences in insulin sensitivity and rate of loss of β-cell function between intervention and control at 6 and 12 months.

RESULTS

Of 507 individuals who were approached, 58 (28 control, 30 intervention) entered the study and 41 completed it. Participants were largely white European males, BMI 24.8 ± 3.8 kg/m² , HbA_1c 75 ± 25 mmol/mol (9 ± 2%). Mean level of objectively measured MVPA increased in the intervention group (mean 243 to 273 min/week) and 61% of intervention participants reached the target of ≥ 150 min/week of self-reported MVPA on at least 42 weeks of the year. Physical activity levels fell slightly in the control group (mean 277 to 235 min of MVPA/week). There was exploratory evidence that intervention group became more insulin sensitive and required less insulin. However, the rate of loss of β-cell function appeared similar between the groups, although the change in insulin sensitivity may have affected this.

CONCLUSION

We show that it is possible to recruit and randomize people with newly diagnosed Type 1 diabetes to a trial of an exercise intervention, and increase and maintain their exercise levels for 12 months. Future trials need to incorporate measures of greater adherence to exercise training targets, and include more appropriate measures of β-cell function. (Clinical Trials Registry No; ISRCTN91388505).