Embracing cancer complexity: Hallmarks of systemic disease

The last 50 years have witnessed extraordinary developments in understanding mechanisms of carcinogenesis, synthesized as the hallmarks of cancer. Despite this logical framework, our understanding of the molecular basis of systemic manifestations and the underlying causes of cancer-related death remains incomplete. Looking forward, elucidating how tumors interact with distant organs and how multifaceted environmental and physiological parameters impinge on tumors and their hosts will be crucial for advances in preventing and more effectively treating human cancers. In this perspective, we discuss complexities of cancer as a systemic disease, including tumor initiation and promotion, tumor micro- and immune macro-environments, aging, metabolism and obesity, cancer cachexia, circadian rhythms, nervous system interactions, tumor-related thrombosis, and the microbiome. Model systems incorporating human genetic variation will be essential to decipher the mechanistic basis of these phenomena and unravel gene-environment interactions, providing a modern synthesis of molecular oncology that is primed to prevent cancers and improve patient quality of life and cancer outcomes.

Inhibition of lactate transport by MCT-1 blockade improves chimeric antigen receptor T-cell therapy against B-cell malignancies

BACKGROUND

Chimeric antigen receptor (CAR) T cells have shown remarkable results against B-cell malignancies, but only a minority of patients have long-term remission. The metabolic requirements of both tumor cells and activated T cells result in production of lactate. The export of lactate is facilitated by expression of monocarboxylate transporter (MCTs). CAR T cells express high levels of MCT-1 and MCT-4 on activation, while certain tumors predominantly express MCT-1.

METHODS

Here, we studied the combination of CD19-specific CAR T-cell therapy with pharmacological blockade of MCT-1 against B-cell lymphoma.

RESULTS

MCT-1 inhibition with small molecules AZD3965 or AR-C155858 induced CAR T-cell metabolic rewiring but their effector function and phenotype remained unchanged, suggesting CAR T cells are insensitive to MCT-1 inhibition. Moreover, improved cytotoxicity in vitro and antitumoral control on mouse models was found with the combination of CAR T cells and MCT-1 blockade.

CONCLUSION

This work highlights the potential of selective targeting of lactate metabolism via MCT-1 in combination with CAR T cells therapies against B-cell malignancies.

Risk and response adapted therapy following autologous stem cell transplant in patients with newly diagnosed multiple myeloma (RADAR (UK-MRA Myeloma XV Trial): study protocol for a phase II/III randomised controlled trial

INTRODUCTION

Multiple myeloma is a plasma cell malignancy that accounts for 1%-2% of newly diagnosed cancers.At diagnosis, approximately 20% of patients can be identified, using cytogenetics, to have inferior survival (high-risk). Additionally, standard-risk patients, with detectable disease (minimal residual disease (MRD)-positive) postautologus stem cell transplant (ASCT), fare worse compared with those who do not (MRD-negative). Research is required to determine whether a risk-adapted approach post-ASCT could further improve patient outcomes.

METHODS

RADAR is a UK, multicentre, risk-adapted, response-guided, open-label, randomised controlled trial for transplant-eligible newly diagnosed multiple myeloma patients, using combinations of lenalidomide (R), cyclophosphamide (Cy), bortezomib (Bor), dexamethasone (D) and isatuximab (Isa).Participants receive RCyBorD(x4) induction therapy, followed by high-dose melphalan and ASCT. Post-ASCT, there are three pathways as follows:A phase III discontinuation design to assess de-escalating therapy in standard-risk MRD-negative patients. Participants receive 12 cycles of Isa maintenance. Those who remain MRD-negative are randomised to either continue or stop treatment.A phase II/III multiarm multistage design to test treatment strategies for treatment escalation in standard-risk MRD-positive patients. Participants are randomised to either; R, RBorD(x4) +R, RIsa, or RBorIsaD(x4) + RIsa.A phase II design to assess the activity of intensive treatment strategies in high-risk patients. Participants are randomised to RBorD(x4) +R or RBorIsaD(x4) + RIsa.1400 participants will be registered to allow for 500, 450 and 172 participants in each pathway. Randomisations are equal and treatment is given until disease progression or intolerance.

ETHICS AND DISSEMINATION

Ethical approval was granted by the London-Central Research Ethics Committee (20/LO/0238) and capacity and capability confirmed by the appropriate local research and development department for each participating centre prior to opening recruitment. Participant informed consent is required before trial registration and reconfirmed post-ASCT. Results will be disseminated by conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ISCRTN46841867.

Abstract 5636: V-delta-1 T cells are resident in the human lung and associate with survival in patients with non-small cell lung cancer in the TRACERx Study

Murine tissues harbour signature, resident γδ T cell compartments with profound yet differential impacts on carcinogenesis. γδ T cell knockout mice have heightened susceptibility to carcinogenesis. However, it is now clear in the murine setting that IFNγ-producing γδ T cells reject tumours whilst IL-17-producing γδ T cells promote them. Nonetheless, many human γδ T cell compartments are distinct from that in mice and vice versa. The extent to which human tissues and tumours harbour resident γδ T cells, their effector function and their role in cancer is less clear. Although a large scale in silico study of 5000+ patients with cancer found that intratumoural γδ T cells were the most important correlate of survival, smaller studies have found that these cells to be associated with either survival or progression. Many historical studies have however been limited by the availability of technologies to rigorously identify, isolate, and examine tissue-resident γδ T cells.

To address these issues, we present data from stage I-III non-small cell lung cancers and paired non-tumour (NT) tissue obtained at primary surgery from 25 patients enrolled in the TRACERx Study. Using flow cytometry and quantitative T cell receptor sequencing, we demonstrate that NT lung tissues harbour a resident population of Vδ1 γδ T cells, entirely distinct to blood. Compared with NT lung tissues, resident-memory and effector-memory Vδ1 T cells are enriched in tumours. RNA sequencing revealed that intratumoural Vδ1 T cells are skewed towards cytolysis and T-helper-1 functions, akin to intratumoural NK and CD8+ T cells. Importantly, we found no evidence of T-helper-17 skew that has been implicated in tumour promotion in murine models. Ongoing remission after surgery was significantly associated with the presence of CD103+ tissue-resident Vδ1 T cells in non-malignant lung tissues and the presence of CD45RA-/CD27+ effector-memory Vδ1 T cells in tumours. Moreover, patients with a greater proportion of intratumoural Vδ1 T cell clones shared with paired NT tissues were more likely to remain in remission, consistent with the cells’ proposed immunosurveillance function in steady state epithelial tissues.

Whilst immunotherapies modulating αβ T cells have been successful for some patients, including those with non-small cell lung cancer, clinical trials of γδ T cells have so far demonstrated poor efficacy in solid cancers. These trials have hitherto exclusively utilised Vδ2 T cells, a subset which is found predominantly in peripheral blood and more commonly associated, albeit still rarely, with IL-17 production. The first-in-human clinical trial of Vδ1 T cell immunotherapy has just opened for patients with acute myeloid leukaemia. Thus, our findings have immediate translational relevance and support the utilisation of these as-yet-untapped Vδ1 T cells in solid cancer immunotherapy.

Citation Format: Yin Wu, Dhruva Biswas, Ieva Usaite, Angelova Mihaela, Stefan Boeing, Takahiro Karasaki, Selvaraju Veeriah, Justyna Czyzewska-Khan, James Reading, Andrew Georgiou, Maise Al-Bakir, Nicholas McGranahan, Mariam Jamal-Hanjani, Allan Hackshaw, TRACERx Consortium, Sergio Quezada, Adrian Hayday, Charles Swanton. V-delta-1 T cells are resident in the human lung and associate with survival in patients with non-small cell lung cancer in the TRACERx Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5636.

543 Sensitive quantification and tracking of the active components of a Clonal Neoantigen T cell (cNeT) therapy: From manufacture to peripheral circulation

Background

Ex-vivo expanded tumour infiltrating lymphocytes (TIL) show promise in delivering durable responses among several solid tumour indications. However, characterising, quantifying and tracking the active component of TIL therapy remains challenging as the expansion process does not distinguish between tumour reactive and bystander T-cells. Achilles Therapeutics has developed ATL001, a patient-specific TIL-based product, manufactured using the VELOS™ process that specifically targets clonal neoantigens present in all tumour cells within a patient. Two Phase I/IIa clinical trials of ATL001 are ongoing in patients with advanced Non-Small Cell Lung Cancer, CHIRON (NCT04032847), and metastatic or recurrent melanoma, THETIS (NCT03997474). Extensive product characterisation and immune-monitoring are performed through Achilles’ manufacturing and translational science programme. This enables precise quantification and characterisation of the active component of this therapy – Clonal Neoantigen T cells (cNeT) – during manufacture and following patient administration, offering unique insight into the mechanism of action of ATL001 and aiding the development of next generation processes.

Methods

ATL001 was manufactured using procured tumour and matched whole blood from 8 patients enrolled in the THETIS (n=5) and CHIRON (n=3) clinical trials. Following administration of ATL001, peripheral blood samples were collected up to week 6. The active component of the product was detected via re-stimulation with clonal neoantigen peptide pools and evaluation of IFN-γ and/or TNF-α production. Deconvolution of individual reactivities was achieved via ELISPOT assays. Immune reconstitution was evaluated by flow cytometry. cNeT expansion was evaluated by restimulation of isolated PBMCs with peptide pools and individual peptide reactivities (ELISPOT).

Results

The median age was 57 (range 30 – 71) and 6/8 patients were male. The median number of previous lines of systemic anti-cancer treatment at the time of ATL001 dosing was 2.5 (range 1 – 5). Proportion of cNeT in manufactured products ranged from 0.20% - 77.43% (mean 26.78%) and unique single peptide reactivities were observed in 7 of 8 products (range 0 – 28, mean 8.6). Post-dosing, cNeTs were detected in 5/8 patients and cNeT expansion was observed in 3/5 patients.

Conclusions

These data underscore our ability to sensitively detect, quantify and track the patient-specific cNeT component of ATL001 – during manufacture and post dosing. As the dataset matures, these metrics of detection and expansion will be correlated with product, clinical and genomic characteristics to determine variables associated with peripheral cNeT dynamics and clinical response.

References

NCT04032847, NCT03997474

Ethics Approval

The first 8 patients described have all been located within the UK and both trials (CHIRON and THETIS) have been approved by the UK MHRA (among other international bodies, e.g FDA). Additionally, these trials have been approved by local ethics boards at active sites within the UK. Patient‘s are fully informed by provided materials and investigators prior to consenting to enrol into either ATL001 trial.

193 The Achilles VELOSTM Process 2 boosts the dose of highly functional clonal neoantigen-reactive T cells for precision personalized cell therapies

Background

Adoptive transfer of ex-vivo expanded tumor-infiltrating lymphocytes (TIL) has shown promise in the clinic. However, the non-specific expansion of TIL and the lack of understanding of the active component of TIL has resulted in poor correlation between clinical response and dose as well as poor understanding of response and resistance mechanisms. The VELOSTM manufacturing process generates a precision and personalized treatment modality by targeting clonal neoantigens with the incorporation of an antigen-specific expansion step to enrich the product for these specificities. Achilles has developed a second generation manufacturing process (VELOSTM Process 2) to boost the neoantigen-reactive cell dose while maintaining key qualitative features associated with function. Here we report the in-depth characterization of clonal neoantigen-reactive T cells (cNeT) products expanded using the two VELOSTM processes.

Methods

Matched tumors and peripheral blood from patients undergoing routine surgery were obtained from patients with primary NSCLC or metastatic melanoma (NCT03517917). TIL were expanded from tumor fragments and peptide pools corresponding to the clonal mutations identified using the PELEUSTM bioinformatics platform were synthesized. cNeT were expanded by co-culture of TIL with peptide-pulsed autologous dendritic cells, with an optimized cytokine cocktail and co-stimulation for Process 2. Neoantigen reactivity was assessed using our proprietary potency assay with peptide pool re-challenge followed by intracellular cytokine staining. Single peptide reactivities were identified using ELISPOT and flow cytometric analysis for in-depth phenotyping of cNeT was performed.

Results

CD3+ T cells displayed higher fold expansion in Process 2 (median 77.4) compared to Process 1 (median 3.8)(n=5). Both processes showed similar CD3+ T cell content (median Process 1=91.3%, Process 2=96.9% n=5) and contained both CD4+ and CD8+ T cells showing reactivity to clonal neoantigens. Proportion of cells responding to neoantigen re-challenge was similar across both processes (median Process 1=19.9% and Process 2=18.2%) leading to higher reactive dose when coupled with higher T cell doses in Process 2. Phenotypically T cells were predominantly effector memory for both processes and Process 2 had lower frequencies of terminally differentiated T cells.

Conclusions

Achilles’ proprietary potency assay enables the optimization of new processes that deliver high cNeT doses to patients by detecting the active drug component. We have generated proof of concept data that supports the transfer of the VELOSTM Process 2 to clinical manufacture for two first-in-human studies for the treatment of solid cancers.

Ethics Approval

The samples for the study were collected under an ethically approved protocol (NCT03517917)

Abstract 1508: Characterization of a novel clonal neoantigen reactive T cell (cNeT) product through a comprehensive translational research program

Adoptive cell therapy (ACT) using ex vivo expanded tumor infiltrating lymphocytes (TIL) has shown great promise as a treatment for metastatic melanoma and has the potential to deliver durable responses in other solid tumors. Clonal neoantigens, which are derived from mutations occurring very early in the tumor development, are present in all cancer cells within a patient and therefore could be the optimal targets for TIL-based therapies. Recently it was shown that the number of clonal neoantigens within a tumor is associated with improved clinical outcomes following checkpoint inhibition in patients with non-small cell lung cancer (NSCLC) and melanoma. An approach that targets multiple clonal neoantigens with specific T cells has the potential to demonstrate high specificity and efficacy whilst mitigating the risk of immune escape.

Achilles Therapeutics is developing a personalized ACT product, ATL001, to target clonal neoantigens, which are identified using tumor exome sequencing and the PELEUS™ bioinformatics platform. Clonal neoantigen reactive T cells (cNeTs) are then manufactured from TIL using the VELOS™ manufacturing process. Two Phase I/IIa clinical trials of ATL001 are ongoing in patients with advanced NSCLC and metastatic or recurrent melanoma.

In common with the development of other ACT products, the key to characterizing and improving cNeT products relies on evaluating a diverse set of exploratory endpoints in early clinical trials, including understanding the procedural, clinical and biological factors that influence cNeT manufacturing rate and product reactivity; monitoring the expansion, persistence and phenotype of the infused cells in vivo and identifying potential biomarkers of clinical activity or safety of cNeTs in treated patients. These insights may suggest further improvements to cNeT product development in ensuing iterations.

The evaluation of these endpoints requires the collection of a rich longitudinal dataset that traces each patient's journey from tissue procurement and cNeT manufacture, to final product infusion and follow up. The data collected will include clinical and disease characteristics, tumor microenvironment insights from exome sequencing and immunohistochemistry of procured tumor, and metrics from the VELOS™ manufacturing process, along with a comprehensive immune-monitoring programme comprising immuno-sequencing, immunophenotyping, bespoke ctDNA panels and reactivity assays at specified timepoints, all to be evaluated against clinical outcomes data. The amalgamation of diverse streams of data requires the development of robust processes and systems for data collection, processing and storage. Furthermore, the evaluation of multiple exploratory endpoints will require integration and modelling of baseline covariates, time-series immune-monitoring and efficacy data, all of which will be described

Citation Format: Michael Epstein, Rebecca Pike, Emma Leire, Jen Middleton, Megan Wileman, Lylia Ouboussad, Leah Manning, Theres Oakes, Eva Pekle, Amy Baker, Mark Brown, Daisy Melandri, Pablo Becker, Anabel Ramirez, Natasa Hadjistephanou, Samra Turaljic, Mariam Jamal-Hanjani, Martin Forster, Iraj Ali, Jane Robertson, Karl Peggs, Sergio Quezada. Characterization of a novel clonal neoantigen reactive T cell (cNeT) product through a comprehensive translational research program [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 1508.

Abstract PL04-02: Targeting regulatory T cells in cancer: From mechanisms to new therapies

Regulatory T cells have a critical role in the maintenance of immune homeostasis in mice and man. However, despite their role in maintaining host integrity, their function is known to be hijacked in the context of cancer. The murine and human tumour microenvironment actively recruits regulatory T cells bearing features of activation such as upregulation of the high affinity IL2Ra (CD25) and the immune-regulatory receptor CTLA-4. In mice, anti-CTLA-4 antibodies are able to promote depletion of Tregs and enhanced tumour control whilst in humans this remains less clear. That said, in human cancers, the number of tumour infiltrating regulatory T cells and their spatial distribution with regards to effector T cells has been negatively associated to patient outcomes, underscoring their negative role in anti-tumour immunity and the need for tools that tamper with their function and number. In this talk I will discuss the role of regulatory T cells in the context of cancer, as well as old and new strategies to target this compartment including the development of a new CD25-targeting Treg depleting antibody for mice and man.

Citation Format: Sergio Quezada. Targeting regulatory T cells in cancer: From mechanisms to new therapies [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 PL04-02.

Potential of Magnetic Hyperthermia to Stimulate Localized Immune Activation

Magnetic hyperthermia (MH) harnesses the heat-releasing properties of superparamagnetic iron oxide nanoparticles (SPIONs) and has potential to stimulate immune activation in the tumor microenvironment whilst sparing surrounding normal tissues. To assess feasibility of localized MH in vivo, SPIONs are injected intratumorally and their fate tracked by Zirconium-89-positron emission tomography, histological analysis, and electron microscopy. Experiments show that an average of 49% (21-87%, n = 9) of SPIONs are retained within the tumor or immediately surrounding tissue. In situ heating is subsequently generated by exposure to an externally applied alternating magnetic field and monitored by thermal imaging. Tissue response to hyperthermia, measured by immunohistochemical image analysis, reveals specific and localized heat-shock protein expression following treatment. Tumor growth inhibition is also observed. To evaluate the potential effects of MH on the immune landscape, flow cytometry is used to characterize immune cells from excised tumors and draining lymph nodes. Results show an influx of activated cytotoxic T cells, alongside an increase in proliferating regulatory T cells, following treatment. Complementary changes are found in draining lymph nodes. In conclusion, results indicate that biologically reactive MH is achievable in vivo and can generate localized changes consistent with an anti-tumor immune response.

IMMU-16. INTRA-TUMOURAL IL-12 DELIVERY ENABLES CAR T-CELL IMMUNOTHERAPY FOR HIGH-GRADE GLIOMA

Treatment with T-cells redirected to tumour specificity with a chimeric antigen receptor (CAR) may be well suited to treat intracranial tumours due to the ability of T-cells to access the central nervous system and migrate to infiltrative sites of disease. In adult glioblastoma, a case report of local and distant eradication of intracranial and spinal tumour deposits following intraventricular infusion of IL13Ra2-CAR T-cells indicates the potential of this approach. However, in contrast to the sustained complete remissions observed in haematological malignancies, in the majority of patients with glioblastoma CAR T-cell therapy has not resulted in clinical benefit. Tumour heterogeneity and the highly immune inhibitory tumour microenvironment (TME) are likely key barriers to achieving durable anti-tumour immunity. Here use intra-tumoural administration of IL-12 to enable CAR T-cell immunity. We employed CAR-T cells targeting the tumour-specific epidermal growth factor variant III (EGFRvIII). In an immunocompetent orthotopic mouse model of high-grade glioma, we show that CAR-T cells alone failed to control fully established tumour, but when combined with a single, locally delivered dose of IL-12, durable antitumor responses were achieved. IL-12 not only boosted cytotoxicity of CAR T-cells, but also reshaped the TME driving increased infiltration of proinflammatory CD4+ T-cells, decreased numbers of regulatory T-cells (Tregs) and activation of the myeloid compartment. Critically, immunotherapy enabling benefits of IL-12 were achieved with minimal systemic effects. Our findings show that local delivery of IL-12 is an effective adjuvant for CAR-T cell therapy for high-grade glioma. Assessment of application in high-risk childhood brain tumours is ongoing.

Abstract A19: Conditional inactivation of SHOC2 in adult mice to study its role in tissue homeostasis

The RAS-RAF-MEK-ERK signaling pathway plays an important role throughout mammalian development, from embryogenesis to tissue-specific cellular homeostasis, and its aberrant activation is a major driver of human cancer. Mouse models have highly improved our current understanding of the RAS-ERK pathway in physiologic and pathologic contexts. RAF activation is a complex process that involves multiple regulatory steps in addition to RAS binding. Key among them is the dephosphorylation of a conserved inhibitory site (S259-RAF1, S365-BRAF) by a phosphatase complex comprising SHOC2, MRAS and PP1 (SHOC2 complex). Work from our lab has proposed the SHOC2 complex has properties of an attractive therapeutic target against RAS-driven tumors that may help overcome the main problems associated with pharmacologic inhibition of the pathway in the clinic, namely, drug resistance and toxicity. In order to study the role of SHOC2 in vivo/in tissue homeostasis we have generated 2 mouse models of conditional SHOC2 inactivation. A knock-out model (KO) was generated by flanking exon 4 with loxP sites. A knock-in (KI) model was generated using a minigene strategy, where wild-type SHOC2 is expressed in a cDNA configuration under its endogenous promoter and replaced after Cre-mediated recombination by a mutant SHOC2 D175N allele that is defective for interaction with MRAS and PP1. SHOC2 KO and KI mice are embryonic lethal, indicating SHOC2 function is required during mouse development. To study SHOC2 function in adult tissue homeostasis, SHOC2 KO and KI mice were crossed with animals carrying an inducible ubiquitously expressed CreERT2 recombinase (R26-CreERT2). Treatment with tamoxifen leads to efficient recombination (>80%) in all tissues examined except brain. Significantly, SHOC2 inactivation is tolerated well in the short term as mice appear normal up to ~10 weeks post-treatment. However, at later times KO female mice start to lose weight and have to be sacrificed after ~14 weeks. Male KO mice do not lose weight but instead develop skin lesions and have to be culled at ~15 weeks. Postmortem studies show both sexes have splenomegaly and swollen lymph nodes consistent with an immune phenotype that is under study. Male KO mice also have swollen bladders, suggesting a sexually dymorphic role for SHOC2 in urinary function. Our mouse studies reveal that SHOC2 inactivation in adult mice appears well tolerated in the short term and thus help validate SHOC2 as a good therapeutic target. However, our studies also reveal new roles for SHOC2 in tissue homeostasis and suggest pleiotropic phenotypes likely to emerge after sustained inhibition.

Citation Format: Sibel Sari, Isabel Boned del Rio, Greg Jones, Jake Henry, Maria De Las Nieves Amalia Peltzer, York Posor, Sergio Quezada, Pablo Rodriguez-Viciana. Conditional inactivation of SHOC2 in adult mice to study its role in tissue homeostasis [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr A19.

Abstract A101: Single-cell analysis reveals the pivotal role of the innate immune compartment in aCTLA-4 antitumor response

Immunotherapies have revolutionized and continue to revolutionize cancer patient care; however, much of our understanding of the mechanism of action of these therapies is currently limited. The accumulation of regulatory T cells (Tregs) in the tumor hampers antitumor activity and correlates with bad prognosis in several human cancers. Anti-CTLA-4 monoclonal antibodies (mAbs) have been extensively studied, and their activity depends both on the blockade of the CTLA-4 coinhibitory molecule, as well as the intratumoral depletion of Tregs, increasing effector cell abundance, and favoring tumor rejection. Fc-gamma receptor (FcgR) coengagement has been proven to be important for the action of aCTLA-4, in addition to its Treg-depleting activity via antibody-dependent cellular cytotoxicity (ADCC); however, it is unclear what are the cellular changes involved. We therefore wished to dissect the differences between aCTLA-4 mIgG1, an antibody that only blocks the CTLA-4 receptor, and aCTLA-4 mIgG2a, which has a dual activity of both blocking the receptor and depleting Tregs. To address this, we performed single-cell RNA-seq of infiltrating leukocytes from tumors in mice treated with aCTLA-4 mIgG1, mIgG2a, or left untreated (UT). This high-resolution comparison revealed unique cellular profiles generated by each treatment. While the blocking-only mIgG1 was similar to UT, mIgG2a with ADCC effector function demonstrated major changes. Tumors in mIgG2a treated mice showed an immediate decline of immune suppressive macrophages, and the emergence of proinflammatory monocytes, as well as NK cells and naive CD8 T cells. In addition, mIgG2a-treated mice displayed a gradual increase of CD4 T-cell subsets throughout treatment. Finally, a vast tissue repair signature was observed in later time points of aCTLA-4 mIgG2a treatment, comprising MRC1+ macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs), while CD8 T-cell abundance declined. In summary, our findings provide an in-depth view of the differences in mechanisms of action between an aCTLA-4 blocking mAb and an optimized blocking-depleting mAb, underscoring how FcgRs coengagement leads to enhanced antitumor response via the innate immune compartment.

Citation Format: Ido Yofe, Adam Jelinski, Isabelle Solomon, Tomer Landsberger, Marc Robert de Massy, Karl Peggs, Sergio Quezada, Ido Amit. Single-cell analysis reveals the pivotal role of the innate immune compartment in aCTLA-4 antitumor response [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A101.

Genomic and Transcriptomic Determinants of Therapy Resistance and Immune Landscape Evolution during Anti-EGFR Treatment in Colorectal Cancer

Despite biomarker stratification, the anti-EGFR antibody cetuximab is only effective against a subgroup of colorectal cancers (CRCs). This genomic and transcriptomic analysis of the cetuximab resistance landscape in 35 RAS wild-type CRCs identified associations of NF1 and non-canonical RAS/RAF aberrations with primary resistance and validated transcriptomic CRC subtypes as non-genetic predictors of benefit. Sixty-four percent of biopsies with acquired resistance harbored no genetic resistance drivers. Most of these had switched from a cetuximab-sensitive transcriptomic subtype at baseline to a fibroblast- and growth factor-rich subtype at progression. Fibroblast-supernatant conferred cetuximab resistance in vitro, confirming a major role for non-genetic resistance through stromal remodeling. Cetuximab treatment increased cytotoxic immune infiltrates and PD-L1 and LAG3 immune checkpoint expression, potentially providing opportunities to treat cetuximab-resistant CRCs with immunotherapy.

Abstract IA36: Regulatory T cells, polymorphisms, and response to checkpoint blockade: From mechanisms to potential biomarkers

In mice, anti-CTLA-4 monoclonal antibodies (mAbs) require Fc-gamma receptor (FcγR)-mediated depletion of intratumoral regulatory T (Treg) cells to promote tumor rejection. However, the relevance of this mechanism in the human setting remains controversial. Using a mouse model expressing human FcγRs, and analysis of clinical samples from ipilimumab-treated melanoma patients, we investigate the potential role of Treg depletion in the activity of antibodies targeting human CTLA-4.

Citation Format: Sergio Quezada. Regulatory T cells, polymorphisms, and response to checkpoint blockade: From mechanisms to potential biomarkers [abstract]. In: Proceedings of the Fifth AACR-IASLC International Joint Conference: Lung Cancer Translational Science from the Bench to the Clinic; Jan 8-11, 2018; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(17_Suppl):Abstract nr IA36.

[Monitoring indicators of the program "Chile Grows with You" 2008-2011]

OBJECTIVE

To monitor coverage and outcomes associated with the activities of the integrated protection system for early childhood Chile Grows with You (CHCC), which includes the comprehensive psychosocial development of children between 18 months and 3 years old, in each of the 29 Health Services of the country, as well as the changes observed after 4 years.

MATERIAL AND METHOD

Database analysis of all local public networks in the country between 2008 and 2011 was performed. The application of the test regarding psychomotor development, prevalence of development delay and risk, participation of mothers in educational workshops, home visits and recovery rate of deficient children by age were studied. Median and observed changes of each indicator were analyzed developing a ranking based on the results observed.

RESULTS

Approximately 75% of children were evaluated, with a prevalence of delay or risk of about 5% and a rate of recovery close to 50%. The participation of mothers in educational workshops increased from 7.6 to 11.0% (p<0.001) and home visits to developmentally delayed children increased 6 times between 2009 and 2011 (p<0.001). Most changes were positive, although the prevalence of developmentally delayed children under 2 years slightly increased (0.6%), and the recovery of 3 year olds decreased (-14.4%). A great variability was observed among the Health Services.

CONCLUSIONS

There are some positive results in relation to psychomotor development, with significant regional differences. A lower than expected deficit rate regarding psychomotor development was observed, which implies the need to further analyze the instrument used or the conditions of application.

Tracking genomic cancer evolution for precision medicine: the lung TRACERx study

The importance of intratumour genetic and functional heterogeneity is increasingly recognised as a driver of cancer progression and survival outcome. Understanding how tumour clonal heterogeneity impacts upon therapeutic outcome, however, is still an area of unmet clinical and scientific need. TRACERx (TRAcking non-small cell lung Cancer Evolution through therapy [Rx]), a prospective study of patients with primary non-small cell lung cancer (NSCLC), aims to define the evolutionary trajectories of lung cancer in both space and time through multiregion and longitudinal tumour sampling and genetic analysis. By following cancers from diagnosis to relapse, tracking the evolutionary trajectories of tumours in relation to therapeutic interventions, and determining the impact of clonal heterogeneity on clinical outcomes, TRACERx may help to identify novel therapeutic targets for NSCLC and may also serve as a model applicable to other cancer types.

Prediction of early and late pre-eclampsia from maternal characteristics, uterine artery Doppler and markers of vasculogenesis during first trimester of pregnancy

OBJECTIVE

To develop a predictive model for pre-eclampsia using clinical, biochemical and ultrasound markers during the first trimester of pregnancy.

METHODS

This was a nested case-control study within a pre-eclampsia screening project that involved 5367 asymptomatic pregnant women undergoing routine transvaginal uterine artery (UtA) Doppler at 11 + 0 to 13 + 6 weeks. Following exclusions, there were 70 pregnant women who later developed pre-eclampsia and 289 control patients enrolled during the first trimester who had serum or plasma samples taken at enrolment available for the purposes of this study. Of these, 17 pregnancies were diagnosed with early-onset (delivery < 34 weeks) pre-eclampsia and 53 with late-onset (delivery ≥ 34 weeks) pre-eclampsia. The lowest, highest and mean of left and right UtA pulsatility indices (PI) were calculated. Blood samples were stored at -84 °C until biochemical analysis for markers of vasculogenesis was performed. The distributions of the lowest UtA-PI and the biochemical markers were adjusted for maternal characteristics, expressed as multiples of the median (MoM), and compared between groups. Logistic regression analysis was used to evaluate if any variable was significantly associated with pre-eclampsia.

RESULTS

Pregnancies that later developed pre-eclampsia were associated with higher maternal prepregnancy body mass index. An increased lowest UtA-PI was significantly associated with both early- and late-onset disease. Placental growth factor (PlGF) MoM was significantly reduced in women who later developed early- or late-onset pre-eclampsia compared with controls (median (interquartile range), 0.69 (0.33-1.46) and 1.10 (0.39-1.56), respectively, vs 1.19 (0.65-1.84), P < 0.05). Different combined models were generated by logistic regression analysis, and the detection rate with a fixed 10% false-positive rate was 47% and 29% for early- and late-onset pre-eclampsia, respectively.

CONCLUSION

Pregnancies that later developed early or late pre-eclampsia were characterized by impaired placentation and an anti-angiogenic state during the first trimester of pregnancy. Regression models which include maternal characteristics, UtA Doppler and PlGF can apparently predict approximately half of pregnancies that will be complicated by early-onset pre-eclampsia. We believe more research in several areas is needed to aid in the creation of a better and more population-specific screening test for pre-eclampsia during the first trimester of pregnancy.