bims-tuchim 2021-06-13 papers

bims-tuchim

Biomed News

on Tumor-on-chip models

Issue of 2021–06–13
sixteen papers selected by
Philipp Albrecht, Friedrich Schiller University

Suppression of tumor-associated neutrophils by lorlatinib attenuates pancreatic cancer growth and improves treatment with immune checkpoint blockade.
Human colorectal cancer-on-chip model to study the microenvironmental influence on early metastatic spread.
Single-cell analyses of renal cell cancers reveal insights into tumor microenvironment, cell of origin, and therapy response.
A risk model developed based on tumor microenvironment predicts overall survival and associates with tumor immunity of patients with lung adenocarcinoma.
Cancer-Associated Fibroblasts and Tumor-Associated Macrophages in Cancer and Cancer Immunotherapy.
Mechanism of action of PD-1 receptor/ligand targeted cancer immunotherapy.
An Eight-Gene Hypoxia Signature Predicts Survival in Pancreatic Cancer and Is Associated With an Immunosuppressed Tumor Microenvironment.
On-chip determination of tissue-specific metastatic potential of breast cancer cells.
The biological underpinnings of therapeutic resistance in pancreatic cancer.
Signaling pathways in cancer-associated fibroblasts and targeted therapy for cancer.
The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment.
Quantifying nanotherapeutic penetration using a hydrogel-based microsystem as a new 3D in vitro platform.
Acidic tumor microenvironment-sensitive liposomes enhance colorectal cancer therapy by acting on both tumor cells and cancer-associated fibroblasts.
Obstacles and Coping Strategies of CAR-T Cell Immunotherapy in Solid Tumors.
A Microfluidic Multisize Spheroid Array for Multiparametric Screening of Anticancer Drugs and Blood-Brain Barrier Transport Properties.
Cancer stem cell-immune cell crosstalk in tumour progression.

Nat Commun. 2021 06 07. 12(1): 3414

Suppression of tumor-associated neutrophils by lorlatinib attenuates pancreatic cancer growth and improves treatment with immune checkpoint blockade.

Sebastian R Nielsen, Jan E Strøbech, Edward R Horton, Rene Jackstadt, Anu Laitala, Marina C Bravo, Giorgia Maltese, Adina R D Jensen, Raphael Reuten, Maria Rafaeva, Saadia A Karim, Chang-Il Hwang, Luis Arnes, David A Tuveson, Owen J Sansom, Jennifer P Morton, Janine T Erler.

Pancreatic ductal adenocarcinoma (PDAC) patients have a 5-year survival rate of only 8% largely due to late diagnosis and insufficient therapeutic options. Neutrophils are among the most abundant immune cell type within the PDAC tumor microenvironment (TME), and are associated with a poor clinical prognosis. However, despite recent advances in understanding neutrophil biology in cancer, therapies targeting tumor-associated neutrophils are lacking. Here, we demonstrate, using pre-clinical mouse models of PDAC, that lorlatinib attenuates PDAC progression by suppressing neutrophil development and mobilization, and by modulating tumor-promoting neutrophil functions within the TME. When combined, lorlatinib also improves the response to anti-PD-1 blockade resulting in more activated CD8 + T cells in PDAC tumors. In summary, this study identifies an effect of lorlatinib in modulating tumor-associated neutrophils, and demonstrates the potential of lorlatinib to treat PDAC.

DOI: https://doi.org/10.1038/s41467-021-23731-7
iScience. 2021 May 21. 24(5): 102509

Human colorectal cancer-on-chip model to study the microenvironmental influence on early metastatic spread.

Carly Strelez, Sujatha Chilakala, Kimya Ghaffarian, Roy Lau, Erin Spiller, Nolan Ung, Danielle Hixon, Ah Young Yoon, Ren X Sun, Heinz-Josef Lenz, Jonathan E Katz, Shannon M Mumenthaler.

  Colorectal cancer (CRC) progression is a complex process that is not well understood. We describe an in vitro organ-on-chip model that emulates in vivo tissue structure and the tumor microenvironment (TME) to better understand intravasation, an early step in metastasis. The CRC-on-chip incorporates fluid flow and peristalsis-like cyclic stretching and consists of endothelial and epithelial compartments, separated by a porous membrane. On-chip imaging and effluent analyses are used to interrogate CRC progression and the resulting cellular heterogeneity. Mass spectrometry-based metabolite profiles are indicative of a CRC disease state. Tumor cells intravasate from the epithelial channel to the endothelial channel, revealing differences in invasion between aggressive and non-aggressive tumor cells. Tuning the TME by peristalsis-like mechanical forces, the epithelial:endothelial interface, and the addition of fibroblasts influences the invasive capabilities of tumor cells. The CRC-on-chip is a tunable human-relevant model system and a valuable tool to study early invasive events in cancer.

Keywords:  Bioengineering; Biomedical materials; Cancer; Classification Description; Tissue engineering

DOI:  https://doi.org/10.1016/j.isci.2021.102509
Proc Natl Acad Sci U S A. 2021 Jun 15. pii: e2103240118. [Epub ahead of print]118(24):

Single-cell analyses of renal cell cancers reveal insights into tumor microenvironment, cell of origin, and therapy response.

Yuping Zhang, Sathiya P Narayanan, Rahul Mannan, Gregory Raskind, Xiaoming Wang, Pankaj Vats, Fengyun Su, Noshad Hosseini, Xuhong Cao, Chandan Kumar-Sinha, Stephanie J Ellison, Thomas J Giordano, Todd M Morgan, Sethuramasundaram Pitchiaya, Ajjai Alva, Rohit Mehra, Marcin Cieslik, Saravana M Dhanasekaran, Arul M Chinnaiyan.

  Diverse subtypes of renal cell carcinomas (RCCs) display a wide spectrum of histomorphologies, proteogenomic alterations, immune cell infiltration patterns, and clinical behavior. Delineating the cells of origin for different RCC subtypes will provide mechanistic insights into their diverse pathobiology. Here, we employed single-cell RNA sequencing (scRNA-seq) to develop benign and malignant renal cell atlases. Using a random forest model trained on this cell atlas, we predicted the putative cell of origin for more than 10 RCC subtypes. scRNA-seq also revealed several attributes of the tumor microenvironment in the most common subtype of kidney cancer, clear cell RCC (ccRCC). We elucidated an active role for tumor epithelia in promoting immune cell infiltration, potentially explaining why ccRCC responds to immune checkpoint inhibitors, despite having a low neoantigen burden. In addition, we characterized an association between high endothelial cell types and lack of response to immunotherapy in ccRCC. Taken together, these single-cell analyses of benign kidney and RCC provide insight into the putative cell of origin for RCC subtypes and highlight the important role of the tumor microenvironment in influencing ccRCC biology and response to therapy.

Keywords:  cell of origin; clear cell renal cell carcinoma; renal cell carcinoma; single-cell RNA sequencing; tumor microenvironment

DOI:  https://doi.org/10.1073/pnas.2103240118
Oncogene. 2021 Jun 09.

A risk model developed based on tumor microenvironment predicts overall survival and associates with tumor immunity of patients with lung adenocarcinoma.

Jie Wu, Lan Li, Huibo Zhang, Yaqi Zhao, Haohan Zhang, Siyi Wu, Bin Xu.

Tumor microenvironment (TME) has been reported to exhibit a crucial effect in lung cancer. Therefore, this study was aimed to investigate the genes associated with TME and develop a risk score to predict the overall survival (OS) of patients with lung adenocarcinoma (LUAD) based on these genes. The immune and stromal scores were generated by the ESTIMATE algorithm for LUAD patients in The Cancer Genome Atlas (TCGA) database. Differentially expressed gene and weighted gene co-expression network analyses were used to derive immune- and stromal-related genes. The Least Absolute Shrinkage and Selection Operator (LASSO)-Cox regression was applied for further selection and the selected genes were inputted into stepwise regression to develop TME-related risk score (TMErisk) which was further validated in Gene Expression Omnibus (GEO) datasets. TMErisk-related biological phenotypes were analyzed in function enrichment, tumor immune signature, and tumor mutation signature. The patient's response to immunotherapy was inferred by the tumor immune dysfunction and exclusion (TIDE) score and immunophenoscore (IPS). According to our results, TMErisk was developed based on SERPINE1, CX3CR1, CD200R1, GBP1, IRF1, STAP1, LOX, and OR7E47P. Furthermore, high TMErisk was identified as a poor factor for OS in TCGA and GEO datasets, as well as in subgroup analysis with different gender, smoking status, age, race, anatomic site, therapies, and tumor-node-metastasis (TNM) stages. Higher TMErisk is also associated negatively with the abundance of B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, and other stromal or immune cells. Several genes of the human leukocyte antigen (HLA) family and immune checkpoints were less expressed in the high-TMErisk group. Mutations of 19 genes occurred more frequently in the high-TMErisk group. These mutations may be associated with TME change and indicate patients' response to immunotherapy. According to our analyses, a lower TMErisk score may indicate better response and OS outcome of immunotherapy.

DOI: https://doi.org/10.1038/s41388-021-01853-y
Front Oncol. 2021 ;11 668731

Cancer-Associated Fibroblasts and Tumor-Associated Macrophages in Cancer and Cancer Immunotherapy.

Hans Raskov, Adile Orhan, Shruti Gaggar, Ismail Gögenur.

  Our understanding of the tumor microenvironment (TME), including the interplay between tumor cells, stromal cells, immune cells, and extracellular matrix components, is mandatory for the innovation of new therapeutic approaches in cancer. The cell-cell communication within the TME plays a pivotal role in the evolution and progression of cancer. Cancer-associated fibroblasts (CAF) and tumor-associated macrophages (TAM) are major cell populations in the stroma of all solid tumors and often exert protumorigenic functions; however, the origin and precise functions of CAF and TAM are still incompletely understood. CAF and TAM hold significant potential as therapeutic targets to improve outcomes in oncology when combined with existing therapies. The regulation of CAF/TAM communication and/or their differentiation could be of high impact for improving the future targeted treatment strategies. Nevertheless, there is much scope for research and innovation in this field with regards to the development of novel drugs. In this review, we elaborate on the current knowledge on CAF and TAM in cancer and cancer immunotherapy. Additionally, by focusing on their heterogenous functions in different stages and types of cancer, we explore their role as potential therapeutic targets and highlight certain aspects of their functions that need further research.

Keywords:  cancer biology; cancer immunotherapy; cancer-associated fibroblasts; tumor microenvironment; tumor-associated macrophages

DOI:  https://doi.org/10.3389/fonc.2021.668731
Eur J Immunol. 2021 Jun 09.

Mechanism of action of PD-1 receptor/ligand targeted cancer immunotherapy.

Jannie Borst, Julia Busselaar, Douwe M T Bosma, Ferry Ossendorp.

  Immunotherapy targeting the Programmed Death (PD-1) receptor/ligand (L) "checkpoint" rapidly gains ground in the treatment of many cancer types. To increase treatment scope and efficacy, predictive biomarkers and rational selection of co-treatments is required. To meet these demands, we must understand PD-1 function in detail. We here outline recent insights into the regulation of the CD8+ T cell response by PD-1. The prevailing view has been that blockade of PD-1/ligand (L) interaction "reinvigorates" cytotoxic T lymphocytes (CTL) that were rendered dysfunctional in the tumor microenvironment (TME). However, this review stresses that tumors continuously communicate with adjacent draining lymph nodes (LNs) and that the PD-1 checkpoint also operates during T cell priming. We clarify the role of the PD-(L)1 system at the T cell/dendritic cell (DC) interface, where it regulates T cell receptor (TCR) signaling and CD28 costimulation and thus controls activation of tumor-specific T cells. We also highlight the importance of CD4+ T cell help during priming, which allows DCs to provide other costimulatory and cytokine signals required for optimal CTL differentiation and likely avoidance of a dysfunctional state. Therefore, we pose that PD-(L)1 blockade should exploit LN function and be combined with "help" signals to optimize CTL efficacy. This article is protected by copyright. All rights reserved.

Keywords:  PD-1; cytotoxic T cell; exhaustion; immunotherapy; priming

DOI:  https://doi.org/10.1002/eji.202048994
Front Immunol. 2021 ;12 680435

An Eight-Gene Hypoxia Signature Predicts Survival in Pancreatic Cancer and Is Associated With an Immunosuppressed Tumor Microenvironment.

Raefa Abou Khouzam, Shyama Prasad Rao, Goutham Hassan Venkatesh, Nagwa Ahmed Zeinelabdin, Stephanie Buart, Maxime Meylan, Manjunath Nimmakayalu, Stéphane Terry, Salem Chouaib.

  Intratumoral hypoxia is a widely established element of the pancreatic tumor microenvironment (TME) promoting immune escape, tumor invasion, and progression, while contributing to treatment resistance and poor survival. Despite this critical role, hypoxia is underrepresented in molecular signatures of pancreatic ductal adenocarcinoma (PDA) and concurrent investigations into the hypoxia-immune status are lacking. In this work a literature-based approach was applied to derive an eight-gene hypoxia signature that was validated in fourteen cancer cell lines and in a cohort of PDA. The eight-gene hypoxia signature was significantly associated with overall survival in two distinct PDA datasets and showed independent prognostic value in multivariate analysis. Comparative analysis of tumors according to their hypoxia score (high versus low) determined that tumors with high hypoxia were significantly less enriched in cytotoxic T-cells, and cytolytic activity. In addition, they had lower expression of cytokines and tumor inflammatory markers, pointing to the signature's ability to discern an immune "cold", hypoxic TME. Combining the signature with an immune metric highlighted a worse survival probability in patients with high hypoxia and low immune reactivity, indicating that this approach could further refine survival estimates. Hypoxia as determined by our signature, was significantly associated with certain immune checkpoint inhibitors (ICI) biomarkers, suggesting that the signature reflects an aspect of the TME that is worth pursuing in future clinical trials. This is the first work of its kind in PDA, and our findings on the hypoxia-immune tumor contexture are not only relevant for ICI but could also guide combinatorial hypoxia-mediated therapeutic strategies in this cancer type.

Keywords:  hypoxia; immunosuppresive; immunotharapy; microenvironment; pancreatic cancer; prognostic; signature; tumor inflammation

DOI:  https://doi.org/10.3389/fimmu.2021.680435
Biotechnol Bioeng. 2021 Jun 10.

On-chip determination of tissue-specific metastatic potential of breast cancer cells.

Burcu Firatligil-Yildirir, Gizem Bati-Ayaz, Ismail Tahmaz, Muge Bilgen, Devrim Pesen-Okvur, Ozden Yalcin-Ozuysal.

  Metastasis is one of the major obstacles for breast cancer patients. Limitations of current models demand the development of custom platforms to predict metastatic potential and homing choices of cancer cells. Here, two organ-on-chip (OoC) platforms, invasion/chemotaxis (IC-chip) and extravasation (EX-chip) were used for the quantitative assessment of invasion and extravasation towards specific tissues. Lung, liver and breast microenvironments were simulated in the chips using tissue specific cells embedded in matrigel. In the IC-chip, invasive MDA-MB-231, but not non-invasive MCF-7 breast cancer cells invaded into lung and liver microenvironments. In the EX-chip, MDA-MB-231 cells extravasated more into the lung compared to the liver and breast microenvironments. In addition, lung-specific MDA-MB-231 clone invaded and extravasated into the lung microenvironment more efficiently than the bone-specific clone. Both invasion/chemotaxis and extravasation results were in agreement with published clinical data. Collectively, our results show that IC-chip and EX-chip, simulating tissue specific microenvironments, can distinguish different in vivo metastatic phenotypes, in vitro. Determination of tissue specific metastatic potential of breast cancer cells is expected to improve diagnosis and help select the ideal therapy. This article is protected by copyright. All rights reserved.

Keywords:  breast cancer; extravasation; invasion; lab-on-a-chip; metastasis

DOI:  https://doi.org/10.1002/bit.27855
Genes Dev. 2021 Jun 11.

The biological underpinnings of therapeutic resistance in pancreatic cancer.

Gregory L Beatty, Gregor Werba, Costas A Lyssiotis, Diane M Simeone.

  Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related mortality in the United States and has only recently achieved a 5-yr survival rate of 10%. This dismal prognosis reflects the remarkable capacity of PDAC to effectively adapt to and resist therapeutic intervention. In this review, we discuss recent advances in our understanding of the biological underpinnings of PDAC and their implications as targetable vulnerabilities in this highly lethal disease.

Keywords:  PDAC; genetics; metabolism; microbiome; pancreatic cancer; pancreatic tumor microenvironment; targeted therapy; therapeutic resistance

DOI:  https://doi.org/10.1101/gad.348523.121
Signal Transduct Target Ther. 2021 Jun 10. 6(1): 218

Signaling pathways in cancer-associated fibroblasts and targeted therapy for cancer.

Fanglong Wu, Jin Yang, Junjiang Liu, Ye Wang, Jingtian Mu, Qingxiang Zeng, Shuzhi Deng, Hongmei Zhou.

To flourish, cancers greatly depend on their surrounding tumor microenvironment (TME), and cancer-associated fibroblasts (CAFs) in TME are critical for cancer occurrence and progression because of their versatile roles in extracellular matrix remodeling, maintenance of stemness, blood vessel formation, modulation of tumor metabolism, immune response, and promotion of cancer cell proliferation, migration, invasion, and therapeutic resistance. CAFs are highly heterogeneous stromal cells and their crosstalk with cancer cells is mediated by a complex and intricate signaling network consisting of transforming growth factor-beta, phosphoinositide 3-kinase/AKT/mammalian target of rapamycin, mitogen-activated protein kinase, Wnt, Janus kinase/signal transducers and activators of transcription, epidermal growth factor receptor, Hippo, and nuclear factor kappa-light-chain-enhancer of activated B cells, etc., signaling pathways. These signals in CAFs exhibit their own special characteristics during the cancer progression and have the potential to be targeted for anticancer therapy. Therefore, a comprehensive understanding of these signaling cascades in interactions between cancer cells and CAFs is necessary to fully realize the pivotal roles of CAFs in cancers. Herein, in this review, we will summarize the enormous amounts of findings on the signals mediating crosstalk of CAFs with cancer cells and its related targets or trials. Further, we hypothesize three potential targeting strategies, including, namely, epithelial-mesenchymal common targets, sequential target perturbation, and crosstalk-directed signaling targets, paving the way for CAF-directed or host cell-directed antitumor therapy.

DOI: https://doi.org/10.1038/s41392-021-00641-0
Front Cell Dev Biol. 2021 ;9 637675

The Role of Tumor-Stroma Interactions in Drug Resistance Within Tumor Microenvironment.

Yanghong Ni, Xiaoting Zhou, Jia Yang, Houhui Shi, Hongyi Li, Xia Zhao, Xuelei Ma.

  Cancer cells resistance to various therapies remains to be a key challenge nowadays. For a long time, scientists focused on tumor cells themselves for the mechanisms of acquired drug resistance. However, recent evidence showed that tumor microenvironment (TME) is essential for regulating immune escape, drug resistance, progression and metastasis of malignant cells. Reciprocal interactions between cancer cells and non-malignant cells within this milieu often reshape the TME and promote drug resistance. Therefore, advanced knowledge about these sophisticated interactions is significant for the design of effective therapeutic approaches. In this review, we highlight cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), T-regulatory lymphocytes (Tregs), mesenchymal stem cells (MSCs), cancer-associated adipocytes (CAAs), and tumor endothelial cells (TECs) existing in TME, as well as their multiple cross-talk with tumor cells, which eventually endows tumor cells with therapeutic resistance.

Keywords:   MSCs; CAFs; TAMs; antineoplastic drug resistance; cell-cell interplays; tumor microenvironment

DOI:  https://doi.org/10.3389/fcell.2021.637675
Lab Chip. 2021 Jun 10.

Quantifying nanotherapeutic penetration using a hydrogel-based microsystem as a new 3D in vitro platform.

Saba Goodarzi, Audrey Prunet, Fabien Rossetti, Guillaume Bort, Olivier Tillement, Erika Porcel, Sandrine Lacombe, Ting-Di Wu, Jean-Luc Guerquin-Kern, Hélène Delanoë-Ayari, François Lux, Charlotte Rivière.

The huge gap between 2D in vitro assays used for drug screening and the in vivo 3D physiological environment hampered reliable predictions for the route and accumulation of nanotherapeutics in vivo. For such nanotherapeutics, multi-cellular tumour spheroids (MCTS) are emerging as a good alternative in vitro model. However, the classical approaches to produce MCTS suffer from low yield, slow process, difficulties in MCTS manipulation and compatibility with high-magnification fluorescence optical microscopy. On the other hand, spheroid-on-chip set-ups developed so far require a practical knowledge of microfluidics difficult to transfer to a cell biology laboratory. We present here a simple yet highly flexible 3D model microsystem consisting of agarose-based microwells. Fully compatible with the multi-well plate format conventionally used in cell biology, our simple process enables the formation of hundreds of reproducible spheroids in a single pipetting. Immunostaining and fluorescence imaging including live high-resolution optical microscopy can be performed in situ, with no manipulation of spheroids. As a proof of principle of the relevance of such an in vitro platform for nanotherapeutic evaluation, this study investigates the kinetics and localisation of nanoparticles within colorectal cancer MCTS cells (HCT-116). The nanoparticles chosen are sub-5 nm ultrasmall nanoparticles made of polysiloxane and gadolinium chelates that can be visualized in MRI (AGuIX®, currently implicated in clinical trials as effective radiosensitizers for radiotherapy) and confocal microscopy after addition of Cy5.5. We show that the amount of AGuIX® nanoparticles within cells is largely different in 2D and 3D. Using our flexible agarose-based microsystems, we are able to resolve spatially and temporally the penetration and distribution of AGuIX® nanoparticles within MCTS. The nanoparticles are first found in both extracellular and intracellular space of MCTS. While the extracellular part is washed away after a few days, we evidenced intracellular localisation of AGuIX®, mainly within the lysosomal compartment, but also occasionally within mitochondria. Hence, our agarose-based microsystem appears as a promising 3D in vitro user-friendly platform for investigation of nanotherapeutic transport, ahead of in vivo studies.

DOI: https://doi.org/10.1039/d1lc00192b
Nanoscale. 2021 Jun 07.

Acidic tumor microenvironment-sensitive liposomes enhance colorectal cancer therapy by acting on both tumor cells and cancer-associated fibroblasts.

Chenglei Li, Zhaohuan Li, Xue Gong, Jianhao Liu, Tingyue Zheng, Fangqing Wang, Jingliang Wu, Bo Zhang.

Cancer-associated fibroblasts (CAFs) play a crucial role in facilitating tumor invasion and metastasis, which act as the "soil" in the tumor microenvironment (TME). Accordingly, it would be a promising strategy to enhance the antitumor effect by killing both tumor cells and CAFs simultaneously. Herein, novel TME acid-responsive liposomes for co-delivery of IRI and 398 (IRI&398-s-LPs) were developed, in which the rapid release of both drugs could be triggered under acidic conditions. Notably, a CT-26/3T3 cell co-culture system was used to mimic the real TME both in vitro and in vivo. Cellular immunofluorescence revealed that IRI&398-s-LPs could efficiently decrease the activation of CAFs. In vitro cytotoxicity evaluation demonstrated that IRI&398-s-LPs exhibited higher cytotoxicity than the other liposomal formulations in the CT-26 and CT-26/3T3 cell co-culture system. In vivo NIRF imaging showed that the IRI&398-s-LPs could increase drug accumulation in the tumor sites. Furthermore, IRI&398-s-LPs not only presented superior in vivo anti-tumor activity in CT-26 bearing BALB/c mice, but also enhanced the effect in CT-26/3T3 cell bearing mice with decreased collagen and CAF biomarker expression. Furthermore, IRI&398-s-LPs also presented superior anti-metastatic efficiency in a lung metastasis model. These results indicated that this combinational strategy for eliminating both tumor cells and CAFs provides a new approach for cancer therapy, and the prepared TME-responsive liposomes for co-delivery of drugs hold promising clinical application prospects.

DOI: https://doi.org/10.1039/d1nr01506k
Front Immunol. 2021 ;12 687822

Obstacles and Coping Strategies of CAR-T Cell Immunotherapy in Solid Tumors.

Lele Miao, Zhengchao Zhang, Zhijian Ren, Futian Tang, Yumin Li.

  Chimeric antigen receptor (CAR) T-cell immunotherapy refers to an adoptive immunotherapy that has rapidly developed in recent years. It is a novel type of treatment that enables T cells to express specific CARs on their surface, then returns these T cells to tumor patients to kill the corresponding tumor cells. Significant strides in CAR-T cell immunotherapy against hematologic malignancies have elicited research interest among scholars in the treatment of solid tumors. Nonetheless, in contrast with the efficacy of CAR-T cell immunotherapy in the treatment of hematologic malignancies, its general efficacy against solid tumors is insignificant. This has been attributed to the complex biological characteristics of solid tumors. CAR-T cells play a better role in solid tumors, for instance by addressing obstacles including the lack of specific targets, inhibition of tumor microenvironment (TME), homing barriers of CAR-T cells, differentiation and depletion of CAR-T cells, inhibition of immune checkpoints, trogocytosis of CAR-T cells, tumor antigen heterogeneity, etc. This paper reviews the obstacles influencing the efficacy of CAR-T cell immunotherapy in solid tumors, their mechanism, and coping strategies, as well as economic restriction of CAR-T cell immunotherapy and its solutions. It aims to provide some references for researchers to better overcome the obstacles that affect the efficacy of CAR-T cells in solid tumors.

Keywords:  chimeric antigen receptor T cell; coping strategies; immunotherapy; obstacles; solid tumors

DOI:  https://doi.org/10.3389/fimmu.2021.687822
Adv Sci (Weinh). 2021 06;8(11): e2004856

A Microfluidic Multisize Spheroid Array for Multiparametric Screening of Anticancer Drugs and Blood-Brain Barrier Transport Properties.

Christoph Eilenberger, Mario Rothbauer, Florian Selinger, Anna Gerhartl, Christian Jordan, Michael Harasek, Barbara Schädl, Johannes Grillari, Julian Weghuber, Winfried Neuhaus, Seta Küpcü, Peter Ertl.

  Physiological-relevant in vitro tissue models with their promise of better predictability have the potential to improve drug screening outcomes in preclinical studies. Despite the advances of spheroid models in pharmaceutical screening applications, variations in spheroid size and consequential altered cell responses often lead to nonreproducible and unpredictable results. Here, a microfluidic multisize spheroid array is established and characterized using liver, lung, colon, and skin cells as well as a triple-culture model of the blood-brain barrier (BBB) to assess the effects of spheroid size on (a) anticancer drug toxicity and (b) compound penetration across an advanced BBB model. The reproducible on-chip generation of 360 spheroids of five dimensions on a well-plate format using an integrated microlens technology is demonstrated. While spheroid size-related IC50 values vary up to 160% using the anticancer drugs cisplatin (CIS) or doxorubicin (DOX), reduced CIS:DOX drug dose combinations eliminate all lung microtumors independent of their sizes. A further application includes optimizing cell seeding ratios and size-dependent compound uptake studies in a perfused BBB model. Generally, smaller BBB-spheroids reveal an 80% higher compound penetration than larger spheroids while verifying the BBB opening effect of mannitol and a spheroid size-related modulation on paracellular transport properties.

Keywords:  anticancer drugs; blood-brain barrier; in vitro tests; microfluidics; multicellular spheroids

DOI:  https://doi.org/10.1002/advs.202004856
Nat Rev Cancer. 2021 Jun 08.

Cancer stem cell-immune cell crosstalk in tumour progression.

Defne Bayik, Justin D Lathia.

Cellular heterogeneity and an immunosuppressive tumour microenvironment are independent yet synergistic drivers of tumour progression and underlie therapeutic resistance. Recent studies have highlighted the complex interaction between these cell-intrinsic and cell-extrinsic mechanisms. The reciprocal communication between cancer stem cells (CSCs) and infiltrating immune cell populations in the tumour microenvironment is a paradigm for these interactions. In this Perspective, we discuss the signalling programmes that simultaneously induce CSCs and reprogramme the immune response to facilitate tumour immune evasion, metastasis and recurrence. We further highlight biological factors that can impact the nature of CSC-immune cell communication. Finally, we discuss targeting opportunities for simultaneous regulation of the CSC niche and immunosurveillance.

DOI: https://doi.org/10.1038/s41568-021-00366-w