cDC2 plasticity and acquisition of a DC3-like phenotype mediated by IL-6 and PGE2 in a patient-derived colorectal cancer organoids model

Metastatic colorectal cancer (CRC) is highly resistant to therapy and prone to recur. The tumor-induced local and systemic immunosuppression allows cancer cells to evade immunosurveillance, facilitating their proliferation and dissemination. Dendritic cells (DCs) are required for the detection, processing, and presentation of tumor antigens, and subsequently for the activation of antigen-specific T cells to orchestrate an effective antitumor response. Notably, successful tumors have evolved mechanisms to disrupt and impair DC functions, underlining the key role of tumor-induced DC dysfunction in promoting tumor growth, metastasis initiation, and treatment resistance. Conventional DC type 2 (cDC2) are highly prevalent in tumors and have been shown to present high phenotypic and functional plasticity in response to tumor-released environmental cues. This plasticity reverberates on both the development of antitumor responses and on the efficacy of immunotherapies in cancer patients. Uncovering the processes, mechanisms, and mediators by which CRC shapes and disrupts cDC2 functions is crucial to restoring their full antitumor potential. In this study, we use our recently developed 3D DC-tumor co-culture system to investigate how patient-derived primary and metastatic CRC organoids modulate cDC2 phenotype and function. We first demonstrate that our collagen-based system displays extensive interaction between cDC2 and tumor organoids. Interestingly, we show that tumor-corrupted cDC2 shift toward a CD14+ population with defective expression of maturation markers, an intermediate phenotype positioned between cDC2 and monocytes, and impaired T-cell activating abilities. This phenotype aligns with the newly defined DC3 (CD14+ CD1c+ CD163+) subset. Remarkably, a comparable population was found to be present in tumor lesions and enriched in the peripheral blood of metastatic CRC patients. Moreover, using EP2 and EP4 receptor antagonists and an anti-IL-6 neutralizing antibody, we determined that the observed phenotype shift is partially mediated by PGE2 and IL-6. Importantly, our system holds promise as a platform for testing therapies aimed at preventing or mitigating tumor-induced DC dysfunction. Overall, our study offers novel and relevant insights into cDC2 (dys)function in CRC that hold relevance for the design of therapeutic approaches.

Magnetic-field induced melting of long-range magnetic order akin to Kitaev insulators in the metallic compound Tb5Si3

There have been constant efforts to find 'exotic' quantum spin-liquid (QSL) materials. Some of the transition metal insulators dominated by the direction-dependent anisotropic exchange interaction ('Kitaev model' for honeycomb network of magnetic ions) are considered to be promising cases for the same. In such Kitaev insulators, QSL is achieved from the zero-field antiferromagnetic state by the application of magnetic-field, suppressing other exchange interactions responsible for magnetic order. Here, we show that the features attributable to long-range magnetic ordering of the intermetallic compound, Tb₅Si₃, (T_N= 69 K), containing honey-comb network of Tb ions, are completely suppressed by a critical applied field,H_cr, in heat-capacity and magnetization data, mimicking the behavior of Kitaev physics candidates. The neutron diffraction patterns as a function ofHreveal that it is an incommensurate magnetic structure that gets suppressed, showing peaks arising from multiple wave vectors beyondH_cr. Increasing magnetic entropy as a function ofHwith a peak in the magnetically ordered state is in support of some kind of magnetic disorder in a narrow field range afterH_cr. Such a high-field behavior for a metallic heavy rare-earth system to our knowledge has not been reported in the past and therefore is intriguing.

Abstract 4028: High-dose short-exposure of osimertinib robustly inhibits growth of patient-derived metastatic colorectal cancer organoids

Despite major interest in tyrosine kinase inhibitors (TKIs) as a treatment option for metastatic colorectal cancer (mCRC), almost all TKIs tested for mCRC fail in early-phase clinical trials. Although showing specific target inhibition at low concentrations, TKIs have a much broader kinase inhibitory potency at higher concentrations. Alternative high dose regimens have been proposed to explore if efficacy can be improved with acceptable toxicity. We used 3D matrix-embedded tumor organoids as a preclinical platform to determine optimal drug exposure, i.e. preclinical pharmacology, and to dissect the mechanisms of action to potentially convert the dismal translational success rate of TKIs for mCRC. We established patient-derived tumor organoids (PDTOs) from mCRC biopsies and, based on favorable physicochemical and pharmacokinetic properties, selected 3 TKIs (sunitinib, cediranib and osimertinib). Following standard IC50 assessment using continuous dosing with a concentration range, we investigated the cytotoxic antitumor effect of high-dose, short-exposure (HDSE) treatment. Five PDTOs were exposed to 20 µM TKI for 1-24h, washed and given normal medium, and PDTO-outgrowth was determined 1 week later. At exposures of 1, 3 and 6h, we measured intra-tumoroid TKI concentrations using a clinically validated LC/MS-MS method. PDTO cell death was observed using live-cell microscopy, and quantified by both caspase 3/7 enzyme activity assay and cleaved caspase-3 immunofluorescent staining. While PDTOs could be categorized for their sensitivity across tested TKIs, all were highly sensitive for osimertinib (IC50 values 0.40-3.8 µM). Lower sensitivity was observed for sunitinib (2.0-10.5 µM) and cediranib (2.5-7.1 µM). Only for osimertinib exposure to 20 µM for 3h was sufficient to block proliferation in all PDTOs. Interestingly, peak intra-tumoroid TKI concentration measurements across PDTOs revealed marked cellular accumulation, indicating an expanded potential for target inhibition. The concentrations correlated with sensitivity: for sunitinib from 1.5 mM for the most sensitive PDTO to 0.72 mM for the least sensitive PDTO. Likewise, the corresponding cediranib concentrations were 0.15 mM vs 0.062 mM. All PDTOs had high intra-tumoroid osimertinib concentrations (0.90-1.6 mM). Lastly, we detected a significant increase in apoptosis after 3h of HDSE with osimertinib. Whereas our HDSE regimen shows promising results for all 3 TKIs, very short exposure with high-dose osimertinib effectively reduces proliferation and induces cell death in all mCRC PDTOs. While this is likely due to high intra-tumoroid concentrations reached by osimertinib—the mechanism of action at these concentrations remains unknown and is subject to further studies. In parallel, we propose that a HDSE osimertinib regimen warrants clinical exploration as a potential new treatment option for mCRC.

Citation Format: Kirti K. Iyer, Dennis Poel, Anne Miggelenbrink, Wouter Kerkhof, Erik van den Hombergh, Loek A. de Jong, Nielka P. van Erp, Daniele V. Tauriello, Henk M. Verheul. High-dose short-exposure of osimertinib robustly inhibits growth of patient-derived metastatic colorectal cancer organoids. [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 4028.

Abstract 418: Elacridar potentiates sunitinib efficacy in colorectal cancer models

For unresectable metastatic colorectal cancer (mCRC), the main treatment strategy is combination chemotherapy, targeted therapy, or immunotherapy. Long-term treatment benefit of these therapies is limited to a small subgroup of patients. To improve treatment outcome, many tyrosine kinase inhibitors (TKIs) have been clinically tested in patients with mCRC. Most failed already in early-phase clinical trials due to intrinsic resistance. ATP Binding Cassette Transporter (ABC)B1- and ABCG2-transporters are known contributors to treatment resistance in mCRC. Therefore, we evaluated whether inhibition of these transporters could potentiate the efficacy of TKIs in colorectal cancer (CRC) models.

CRC cell lines, HT29, COLO320 and CACO2 and newly established patient-derived tumor organoids (PDTOs) from mCRC biopsies were first analyzed for the presence of ABCB1 and ABCG2 expression. Models that expressed ABCB1 or ABCG2 were pre-incubated with a non-toxic dose of elacridar, a potent transporter inhibitor, and exposed to a concertation range of three TKIs; sunitinib, cediranib and osimertinib. Next, we measured intracellular drug concentrations using LC/MS-MS one hour after TKI exposure (20 µM) with or without pre-incubation of elacridar. Using the fluorescent properties of sunitinib, we performed live-cell imaging to compare intracellular sunitinib distribution in cells that were or were not pre-incubated with elacridar.

ABCB1 and ABCG2 expression was observed in all CRC models except for HT29 cells, which did not express ABCB1. Pre-incubation with elacridar significantly improved sunitinib efficacy in CRC cells. The IC50 decreased from 2.15 µM to 1.17 µM (p = 0.04), from 1.32 µM to 0.44 µM (p = 0.03), and from 4.94 µM to 3.43 µM (p = 0.03) for HT29, COLO320 and CACO2 cells respectively. This effect was not observed for cediranib and osimertinib. Although not significant, for both PDTO models tested, the IC50 for sunitinib decreased from 8.04 µM to 3.29 µM and from 6.93 µM to 4.16 µM. Intracellular sunitinib concentrations in the tested CRC cell models after sunitinib exposure ranged from 2.46 mM to 4.13 mM without elacridar and from 0.38 mM µM to 1.31 mM when pre-incubated with elacridar (p < 0.01). Live-cell imaging of CRC cells revealed a different pattern of intracellular sunitinib accumulation with and without pre-incubation with elacridar.

Inhibition of multi-drug resistance proteins ABCB1 and ABCG2 with the clinically tested selective transporter inhibitor elacridar potentiates sunitinib efficacy in CRC models. Interestingly, this was accompanied with reduced intracellular sunitinib accumulation. Further research in mCRC PDTOs is warranted to confirm whether this mechanism is involved in intrinsic TKI resistance and therefore contribute to the early-phase failure of clinical trials testing TKIs for mCRC.

Citation Format: Dennis Poel, Kirti K. Iyer, Bob van Gasteren, Beau Dagniaux, Erik van den Hombergh, Nielka P. van Erp, Daniele V. Tauriello, Henk M. Verheul. Elacridar potentiates sunitinib efficacy in colorectal cancer models [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 418.

Dendritic cell phenotype and function in a 3D co-culture model of patient-derived metastatic colorectal cancer organoids

Colorectal cancer (CRC) remains one of the most aggressive and lethal cancers, with metastasis accounting for most deaths. As such, there is an unmet need for improved therapies for metastatic CRC (mCRC). Currently, the research focus is shifting towards the reciprocal interactions within the tumor microenvironment (TME), which prevent tumor clearance by the immune system. Dendritic cells (DCs) play a key role in the initiation and amplification of anti-tumor immune responses and in driving the clinical success of immunotherapies. Dissecting the interactions between DCs and CRC cells may open doors to identifying key mediators in tumor progression, and possible therapeutic targets. This requires representative, robust and versatile models and tools. Currently, there is a shortage of such in vitro systems to model the CRC TME and its tumor-immune cell interactions. Here we develop and establish a dynamic organotypic 3D co-culture system to recapitulate and untangle the interactions between DCs and patient-derived mCRC tumor organoids. To our knowledge, this is the first study investigating human DCs in co-culture with tumor organoids in a 3D, organotypic setting. This system reveals how mCRC organoids modulate and shape monocyte-derived DCs (MoDCs) behavior, phenotype, and function, within a collagen matrix, using techniques such as brightfield and fluorescence microscopy, flow cytometry, and fluorescence-activated cell sorting. Our 3D co-culture model shows high viability and extensive interaction between DCs and tumor organoids, and its structure resembles patient tissue sections. Furthermore, it is possible to retrieve DCs from the co-cultures and characterize their phenotypic and functional profile. In our study, the expression of activation markers in both mature and immature DCs and their ability to activate T cells were impacted by co-culture with tumor organoids. In the future, this direct co-culture platform can be adapted and exploited to study the CRC-DC interplay in more detail, enabling novel and broader insights into CRC-driven DC (dys)function.

A reentrant phenomenon in magnetic and dielectric properties of Dy2BaNiO5 and an intriguing influence of external magnetic field

We report that the spin-chain compound Dy2BaNiO5, recently proven by us to exhibit magnetoelectric coupling below its Néel temperature (TN) of 58 K, exhibits strong frequency-dependent behavior in ac magnetic susceptibility and complex dielectric properties at low temperatures (<10 K), mimicking the 'reentrant' multiglass phenomenon. Such a behavior is not known among undoped compounds. A new finding in the field of multiferroics is that the characteristic magnetic feature at low temperatures moves towards higher temperatures in the presence of a magnetic field (H), whereas the corresponding dielectric feature shifts towards lower temperatures with H, unlike the situation near TN. This observation indicates that the alignment of spins by external magnetic fields tends to inhibit glassy-like slow electric-dipole dynamics, at least in this system, possibly arising from peculiarities in the magnetic structure.

Selective nanoprobes for 'signalling gases'

The use of arrays of chemical detectors has been realized in electronic nose applications. Recently attention has been focused on the application of e-Noses in the medical arena. These are electronic devices that typically employ non-selective gas sensitive elements for the monitoring of odours and other gaseous analytes. Currently, the lack of relative specificity to a mixture of gaseous analytes for these sensing elements makes the use of pattern recognition algorithms to process the signal and match the acquired data profile to a known pattern necessary, thus identifying the signature of the odour or gas detected. An alternative approach to chemical detection through the use of small arrays (two or three elements) of selective gas sensors made of nanostructured semiconducting films and membranes is described in this work. Sensor selectivity is defined here as higher sensitivity to a given gas or class of gases in the presence of interfering gaseous species. Transition metal oxides are key sensing elements of resistive type chemical detectors. A given oxide may be found in several polymorph phases, each having a distinct structural configuration. Gas-oxide interactions are strongly dependent on the 'structure sensitivity' of the polymorph used in sensing. This paper reviews the effect of polymorphism on the gas specificity and the importance of nanoscale processing for stabilizing the desirable oxide phases, and it introduces a gas-polymorph selection library for building the next generation of gas sensing systems with inherent selectivity to be used as non-invasive disease diagnosis tools.