930 Fibroblast activation protein alpha expression in tumor stroma and its association with immuno-regulatory circuits across epithelial tumors

Background

Carcinoma associated fibroblasts (CAFs) play important roles in modulating tumor development and prognosis through biochemical and biomechanical signals, but also through their immuno-modulatory characteristics. Fibroblast activation protein alpha (FAP), a serine protease with selectively high expression on CAFs, may be an ideal target for therapeutic intervention, including cancer immunotherapy. Therefore, a thorough understanding of FAP expression, but also immune cell composition and especially their interaction is key to optimally inform drug development and patient enrichment strategies.

Methods

Formalin-fixed paraffin embedded tissue specimens comprising 253 primary tumors and 277 metastatic lesions were included in this study. Tumor sections were analyzed by digital immunohistochemistry (IHC) to assess tumor-stroma composition, FAP content and immune cell infiltration, complemented by transcriptomic analyses.

Results

Across different types of epithelial tumors, FAP was detected by digital IHC in the tumor-associated stroma at a low to moderate proportion and with heterogeneous distribution patterns. Primary tumors in breast and lung cancer demonstrated a higher median FAP content (6.5% and 6.6% area coverage, respectively) compared to renal cell carcinoma (0.2% area coverage), which was confirmed on mRNA expression level. Median FAP levels were similar between primary and metastatic lesions in most tumor types except for renal cancer, for which FAP levels were significantly increased in metastasis lesions (3.3% area coverage). FAP content positively correlated with the density of FoxP3 positive regulatory T cells, but indication and tissue type specific differences were observed. Transcriptomic analysis revealed that both stroma-richness as well as higher FAP content were positively correlated with macrophage and dendritic cell gene signatures. However, while a higher stromal content was associated with signatures related to endothelial cells and preadipocytes, higher FAP content showed a stronger correlation with regulatory T cells. These findings are suggestive of a distinct biological role of FAP positive stroma in human tumors.

Conclusions

FAP-targeted therapy is a promising strategy to optimize accumulation and action of anti-cancer drugs in the tumor microenvironment, potentially leading to more specific and effective therapies. Our study further elucidates the role of FAP by providing a comprehensive and granular landscape of FAP content in primary and metastatic tumor lesions derived from the same patient population and its association with immune cell composition. Future studies aim to elucidate the complex and dynamic interplay between malignant, stromal and immune cell populations in both temporal and spatial contexts and how that contributes to outcome in cancer immunotherapy.

527 Digital spatial profiling of paired tumor biopsies reveals indoleamine 2,3-dioxygenase (IDO)1 as a potential resistance mechanism for a tumor-targeted 4–1BB agonist in patients with solid tumors

Background

We previously described the capacity of RO7122290 (RO) - a FAP-targeted 4-1BB bispecific antibody - to induce CD8+ T cell infiltration and activation in the tumor (Moreno V. et al, SITC 2020). Aiming to compare pharmacodynamic (PD) changes in tumor nests and stroma, paired tumor biopsies from patients treated with RO (Part A) and RO + atezolizumab (Part B) were analysed by digital spatial profiling (DSP, Nanostring).

Methods

Seven paired (baseline and on-treatment) FFPE tumor tissue biopsies (three from Part A, four from Part B) obtained from an ongoing Phase 1/1b trial (EUDRACT 2017-003961-83) were assessed for mRNA and protein expression. Biopsies were taken from six different tumor types at different RO doses. Up to twelve Regions of Interest (ROIs) were collected per slide and the morphology markers PanCK, CD8, CD3 and DAPI were applied. The ROIs were further annotated in tumor nests and stroma segments based on PanCK staining. The immune-oncology 58-plex protein and 78-plex mRNA expression panels (Nanostring) were used to profile all samples. Data were normalized according to Nanostring guidelines and filtered based on relevance (absolute log2 fold change > 1) and significance (FDR < 0.05, p-value).

Results

The level of CD8+ T cell infiltration measured by spatial profiling correlated with the level measured by IHC, in both tumor nests and stroma. The activation markers 4-1BB and PD-1 were upregulated, confirming the PD effect already measured by mRNA sequencing. We also identified novel protein markers - CD40, PD-L1 and IDO1 - being upregulated after treatment. Spatial regulation differed among the markers with 4-1BB, PD-1 and CD40 upregulated only in the stroma, PD-L1 and IDO1 upregulated in the tumor nests and in the stroma. IDO1 induction is particularly relevant, since this protein is known to attenuate 4-1BB-mediated effector responses. Conventional IHC analysis performed on 14 paired biopsies confirmed IDO1 being upregulated in 11 out of 14 cases and revealed dendritic cells, macrophages and stromal cells to express IDO1. Importantly, IDO1 upregulation was observed in both Part A (3 out of 3) and Part B (8 out of 11).

Conclusions

Spatial profiling allowed us to identify key markers that are spatially regulated after treatment and to gain new insights on the MoA of RO. The induction of IDO1 by RO confirms the dual immunoregulatory nature of 4-1BB signaling and highlights IDO1 as a potential resistance mechanism for RO in the clinical setting, both as single agent and in combination with atezolizumab.

Trial Registration

EUDRACT Number:

2017-003961-83; Protocol Number: BP40087

References

Moreno V. et al, Pharmacodynamic assessment of a novel FAP-targeted 4–1BB agonist, administered as single agent and in combination with atezolizumab to patients with advanced solid tumors, Nov 1 2020, Journal for ImmunoTherapy of Cancer, presented at SITC 2020

Biomarker Technologies to Support Early Clinical Immuno-oncology Development: Advances and Interpretation

Today, there is a huge effort to develop cancer immunotherapeutics capable of combating cancer cells as well as the biological environment in which they can grow, adapt, and survive. For such treatments to benefit more patients, there is a great need to dissect the complex interplays between tumor cells and the host's immune system. Monitoring mechanisms of resistance to immunotherapeutics can delineate the evolution of key players capable of driving an efficacious antitumor immune response. In doing so, simultaneous and systematic interrogation of multiple biomarkers beyond single biomarker approaches needs to be undertaken. Zooming into cell-to-cell interactions using technological advancements with unprecedented cellular resolution such as single-cell spatial transcriptomics, advanced tissue histology approaches, and new molecular immune profiling tools promises to provide a unique level of molecular granularity of the tumor environment and may support better decision-making during drug development. This review will focus on how such technological tools are applied in clinical settings, to inform the underlying tumor-immune biology of patients and offer a deeper understanding of cancer immune responsiveness to immuno-oncology treatments.

Abstract 2270: RG7769 (PD1-TIM3), a novel heterodimeric avidity-driven T cell specific PD-1/TIM-3 bispecific antibody lacking Fc-mediated effector functions for dual checkpoint inhibition to reactivate dysfunctional T cells

Based on the unprecedented clinical efficacy of PD-1/PD-L1 pathway checkpoint inhibitors (CPI), non-redundant immune checkpoints like TIM-3, LAG-3, TIGIT or BTLA are currently being targeted, by combinatorial approaches using monospecific or bispecific antibodies. Up-regulation of TIM-3 has been described as an adaptive CPI resistance mechanism, and internal prevalence data on archival samples of CPI-naïve and -experienced patients showed co-expression of PD-1 and TIM-3 in various tumor types, consistent with literature reports. Here, we describe RG7769 (PD1-TIM3), a novel avidity driven heterodimeric PD-1/TIM-3 1+1 bispecific CrossMabVH-VL intentionally designed as high affinity PD-1 (KD 250 pM, 37°C) and low affinity TIM-3 (KD 130 nM, 37°C) Fab-moieties to specifically target PD-1+ and PD-1+ TIM-3+ T cells through avidity gain, while bypassing PD-1- TIM3+ myeloid and NK cells. In contrast to IgG4-based PD-1 antibodies and conventional IgG1-based TIM-3 Fc-effector function competent antibodies, RG7769 harbors a PG LALA containing heterodimeric KiH IgG1 Fc-region rendering the BsAb refractory to drug shaving by FcgR-expressing macrophages in the TME, while retaining IgG-pharmacokinetics. RG7769 binds to PD-1 with higher affinity than pembrolizumab and nivolumab. X-ray crystallography demonstrated that the humanized PD-1 binding Fab recognizes a unique glycosylated epitope on PD-1, and potently blocks the PD-1/PD-L1 and PD-1/PD-L2 interactions in both biochemical and reporter cell line assays. The humanized TIM-3 binding arm was identified for maximal functional activity using mixed lymphocyte reaction (MLR) assays. Compared with bivalent TIM-3 antibodies, RG7769 shows reduced binding to TIM-3+ myeloid and NK cells, but binds preferentially to dysfunctional T cells expressing PD-1 or both PD-1 and TIM-3, like tumor infiltrating lymphocytes (TILs) in the tumor microenvironment. By virtue of its monovalency, RG7769 induced low antibody internalization on activated T cells when compared with bivalent TIM-3 antibodies, overcoming a major cellular sink for TIM-3 antibodies. In functional assays, RG7769 showed increased IFN-γ secretion by in vitro generated tumor-specific T-cells, increased ex vivo tumor-specific effector functions of T cells from PBMCs of melanoma patients, and enhanced the anti-tumor-activity of TILs from melanoma patients when compared to the monospecific parental PD-1 antibody. Finally, RG7769 showed superior efficacy in controlling s.c. MC38 tumor growth in huPD-1/huTIM-3 transgenic C57/BL6 mice compared to the parental PD-1 antibody. In summary, these preclinical data support the use of RG7769 as a monotherapy and as combination partner for the treatment of patients with solid/hematological tumors. A phase I study is currently ongoing in patients with advanced metastatic solid tumors (NCT03708328).

Citation Format: Laura Laura Codarri Deak, Stefan Seeber, Mario Perro, Patrick Weber, Laura Lauener, Standford Chen, Sonja Offner, Stefan Dengl, Friederike Hesse, Adrian Zwick, Marco Boettger, Alexander Bujotzek, Jörg Benz, Guy Georges, Georg Fertig, Valeria Lifke, Jens Fischer, Stephane Leclair, Victor Levitsky, Marta Canamero, Juha Lindner, Sara Colombetti, Stefanie Bendels, Christophe Boetsch, Matthias Fueth, Merlind Muecke, Henry Kao, Pablo Umana, Christian Klein. RG7769 (PD1-TIM3), a novel heterodimeric avidity-driven T cell specific PD-1/TIM-3 bispecific antibody lacking Fc-mediated effector functions for dual checkpoint inhibition to reactivate dysfunctional T cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2270.

Immunohistochemical Method and Histopathology Judging for the Systemic Synuclein Sampling Study (S4)

Immunohistochemical (IHC) α-synuclein (Asyn) pathology in peripheral biopsies may be a biomarker of Parkinson disease (PD). The multi-center Systemic Synuclein Sampling Study (S4) is evaluating IHC Asyn pathology within skin, colon and submandibular gland biopsies from 60 PD and 20 control subjects. Asyn pathology is being evaluated by a blinded panel of specially trained neuropathologists. Preliminary work assessed 2 candidate immunoperoxidase methods using a set of PD and control autopsy-derived sections from formalin-fixed, paraffin-embedded blocks of the 3 tissues. Both methods had 100% specificity; one, utilizing the 5C12 monoclonal antibody, was more sensitive in skin (67% vs 33%), and was chosen for further use in S4. Four trainee neuropathologists were trained to perform S4 histopathology readings; in subsequent testing, their scoring was compared to that of the trainer neuropathologist on both glass slides and digital images. Specificity and sensitivity were both close to 100% with all readers in all tissue types on both glass slides and digital images except for skin, where sensitivity averaged 75% with digital images and 83.5% with glass slides. Semiquantitative (0-3) density score agreement between trainees and trainer averaged 67% for glass slides and 62% for digital images.

Abstract 492: Spatial overlap analysis of myeloid and T cell compartments identifies distinct subgroups in the cohort of selected colorectal primary tumors

The immune contexture of colorectal cancer (CRC) tumors classifies clinically relevant immune subtypes that are extensively studied. Recent developments in digital computational pathology supporting spatial characterization of tumor immune infiltrate allow more comprehensive analysis of relevant cell to cell interactions. Leveraging that methodology in the current study, we tried to address the question how the distribution of myeloid cells in the tumor microenvironment (TME) of CRC affects the effector functions and distribution of cytotoxic T cells.

We applied multicolored immunohistochemistry to identify monocytic (CD11b/CD14) and granulocytic (CD11b/CD15) myeloid cell populations together with proliferating and non-proliferating cytotoxic T cells (Ki67/CD8). Through automated object detection and image registration using HALO software (IndicaLab), we measured the extent of overlap between the areas occupied by myeloid and T cells. Subsequently, we correlated it with other parameters such as CD8 T cell proliferation ratio, amount of necrosis, MMR status, tumor mutational burden and CMS classes. With this approach, we identified distinct categories of CRC based on the myeloid - T cell overlap irrespective of the MMR status. These categories reflect certain functional areas in the TME and correlate with specific gene signatures that mainly include T effector and memory together with myeloid inflammatory and immunosuppressive signatures.

Our results emphasize the importance of analyzing spatial organization of immune infiltrate in TME and shed a new light on myeloid and T cell interactions in CRC. The approach we used has a potential to be applied in immunotherapy related biomarker studies.

Citation Format: Natalie Zwing, Marta Canamero, Fabien Gaire, Konstanty Korski. Spatial overlap analysis of myeloid and T cell compartments identifies distinct subgroups in the cohort of selected colorectal primary tumors [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 492.

Abstract B47: Unraveling tumor metabolism with in silico IHC multiplexing supported by automated imaging analysis

The aim of our study is to understand and characterize tumor biology and its metabolism by evaluating some of the most relevant hallmarks of cancer like hypoxia, apoptosis, tumor proliferation, angiogenesis and immune status.

We selected from our tissue bank FFPE blocks from 3 main tumor indications (CRC, GC, RCC) analyzed with 9 different markers: CA9, CC3, Ki67, CD34, aSMA, Podoplanin, CD3, CD8 and FOXP3 in consecutive sections. We applied 2 triplex, one duplex and one single IHC assays. After quality check made by board certified pathologist, all slides were scanned with the iScan-HT scanner (VENTANA) at 20x magnification and the whole slide sections were analyzed with help of automated imaging algorithms developed in house.

Tumors harbor different metabolic states. Our cutting-edge approach enables comprehensive understanding of the interactions among different tumor components with respect to tumor metabolism and immune infiltration. Our automated image analysis tool is able to reconstruct and understand the architectural patterns of different tumor metabolic states and to show distribution of hypoxia (CA9), proliferation (Ki67), cell death (CC3), angiogenesis (CD34/aSMA/Podoplanin) and immune cells (CD8/CD3, FOXP3).

Deep understanding of tumor biology and metabolism is crucial for guiding drug development and overcoming challenges in clinical translation.

Citation Format: Suzana Vega Harring, Marta Canamero, Konstanty Korski, Georges Marchal, Oliver Grimm, Claudia Ferreira, Joerg Bredno, Christophe Chefd`hotel, Fabien Gaire. Unraveling tumor metabolism with in silico IHC multiplexing supported by automated imaging analysis. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B47.

Reduced efficacy of the Plk1 inhibitor BI 2536 on the progression of hepatocellular carcinoma due to low intratumoral drug levels

Highly promising preclinical data obtained in cultured cells and in nude mice bearing xenografts contrast with the rather modest clinical efficacy of Polo-like kinase 1 (Plk1) inhibitors. In the present study, we investigated if Plk1 might be a suitable target in hepatocellular carcinoma (HCC) and if a genetically engineered mouse tumor model that well reflects the tumor cell and micro-environmental features of naturally occurring cancers might be suitable to study anti-Plk1 therapy. Analysis of Plk1 expression in human HCC samples confirmed that HCC express much higher Plk1 levels than the adjacent normal liver tissue. Inhibition of Plk1 by an adenovirus encoding for a short hairpin RNA against Plk1 or by the small-molecule inhibitor BI 2536 reduced the viability of HCC cell lines and inhibited HCC xenograft progression in nude mice. Treatment of transforming growth factor (TGF) α/c-myc bitransgenic mice with BI 2536 during hepatocarcinogenesis reduced the number of dysplastic foci and of Ki-67-positive cells within the foci, indicating diminished tumorigenesis. In contrast, BI 2536 had no significant effect on HCC progression in the transgenic mouse HCC model as revealed by magnetic resonance imaging. Measurement of BI 2536 by mass spectrometry revealed considerably lower BI 2536 levels in HCC compared with the adjacent normal liver tissue. In conclusion, low intratumoral levels are a novel mechanism of resistance to the Plk1 inhibitor BI 2536. Plk1 inhibitors achieving sufficient intratumoral levels are highly promising in HCC treatment.

Oncogenicity of the developmental transcription factor Sox9

SOX9 [sex-determining region Y (SRY)-box 9 protein], a high mobility group box transcription factor, plays critical roles during embryogenesis and its activity is required for development, differentiation, and lineage commitment in various tissues including the intestinal epithelium. Here, we present functional and clinical data of a broadly important role for SOX9 in tumorigenesis. SOX9 was overexpressed in a wide range of human cancers, where its expression correlated with malignant character and progression. Gain of SOX9 copy number is detected in some primary colorectal cancers. SOX9 exhibited several pro-oncogenic properties, including the ability to promote proliferation, inhibit senescence, and collaborate with other oncogenes in neoplastic transformation. In primary mouse embryo fibroblasts and colorectal cancer cells, SOX9 expression facilitated tumor growth and progression whereas its inactivation reduced tumorigenicity. Mechanistically, we have found that Sox9 directly binds and activates the promoter of the polycomb Bmi1, whose upregulation represses the tumor suppressor Ink4a/Arf locus. In agreement with this, human colorectal cancers showed a positive correlation between expression levels of SOX9 and BMI1 and a negative correlation between SOX9 and ARF in clinical samples. Taken together, our findings provide direct mechanistic evidence of the involvement of SOX9 in neoplastic pathobiology, particularly, in colorectal cancer.

The distribution and expression of the Bloom's syndrome gene product in normal and neoplastic human cells

Bloom's syndrome (BS) is an autosomal recessive disorder associated with a predisposition to cancers of all types. Cells from BS sufferers display extreme genomic instability. The BS gene product, BLM, is a 159 kDa DNA helicase enzyme belonging to the RecQ family. Here, we have analysed the distribution of BLM in normal and tumour tissues from humans using a recently characterized, specific monoclonal antibody. BLM was found to be localized to nuclei in normal lymphoid tissues, but was largely absent from other normal tissues analysed with the exception of the proliferating compartment of certain tissues. In contrast, expression of BLM was observed in a variety of tumours of both lymphoid and epithelial origin. A strong correlation was observed between expression of BLM and the proliferative status of cells, as determined by staining for markers of cell proliferation (PCNA and Ki67). We conclude that BLM is a proliferation marker in normal and neoplastic cells in vivo, and, as a consequence, is expressed at a higher level in tumours than in normal quiescent tissues.