Microenvironment Of Solid Tumors Research Articles

An Endoplasmic Reticulum Targeting Type I Photosensitizer for Effective Photodynamic Therapy against Hypoxic Tumor Cells.

Organelle-targeted type I photodynamic therapy (PDT) shows great potential to overcome the hypoxic microenvironment in solid tumors. The endoplasmic reticulum (ER) is an indispensable organelle in cells with important biological functions. When the ER is damaged due to the production of reactive oxygen species (ROS), the accumulation of misfolded proteins will interfere with ER homeostasis, resulting in ER stress. Here, an ER-targeted benzophenothiazine-based photosensitizer NBS-ER was presented. ER targeting modification significantly reduced the dark toxicity and improved phototoxicity index (PI). NBS-ER could effectively produce O2 - ⋅ with near-infrared irradiation, making its phototoxicity under hypoxia close to that under normoxia. Meanwhile, the photoinduced ROS triggered ER stress and induced apoptosis. In addition, NBS-ER possessed excellent photodynamic therapeutic effect in 4T1-tumor-bearing mice.

Targeted delivery of liposomal chemoimmunotherapy for cancer treatment.

Chemoimmunotherapy that utilizes the immunomodulatory effect of chemotherapeutics has shown great promise for treating poorly immunogenic solid tumors. However, there remains a significant room for improving the synergy between chemotherapy and immunotherapy, including the efficient, concurrent delivery of chemotherapeutics and immunomodulators into tumors. Here, we report the use of metabolic glycan labeling to facilitate cancer-targeted delivery of liposomal chemoimmunotherapy. 4T1 triple-negative breast cancer cells can be metabolically labeled with azido groups for subsequently targeted conjugation of dibenzocycoloctyne (DBCO)-bearing liposomes loaded with doxorubicin and imiquimod (R837) adjuvant via efficient click chemistry. The encased doxorubicin can induce the immunogenic death of cancer cells and upregulate the expression of CD47 and calreticulin on the surface of cancer cells, while R837 can activate dendritic cells for enhanced processing and presentation of tumor antigens. Targeted delivery of liposomes encapsulating doxorubicin and R837 to 4T1 tumors, enabled by metabolic glycan labeling and click chemistry, showed the promise to reshape the immunosuppressive tumor microenvironment of solid tumors. This cancer-targetable liposomal chemoimmunotherapy could provide a new approach to improving conventional chemotherapy.

Advances and Hurdles in CAR T Cell Immune Therapy for Solid Tumors.

Simple SummaryChimeric antigen receptor (CAR) T cells are genetically engineered T cells that recognize markers present on tumor cells and drive the degradation of the tumor itself. CAR T immunotherapy has obtained remarkable success in targeting a number of blood malignancies; however, its outcome is typically modest when applied to solid tumors, because of specific structural, biological, and metabolic aspects of the solid tumor environment. This article offers an overview of the interactions between CAR T cells and the solid tumor microenvironment, highlighting the main strategies that have been attempted to overcome CAR T suppression, both in preclinical models and in clinical trials.Chimeric antigen receptor (CAR) T cells in solid tumors have so far yielded limited results, in terms of therapeutic effects, as compared to the dramatic results observed for hematological malignancies. Many factors involve both the tumor cells and the microenvironment. The lack of specific target antigens and severe, potentially fatal, toxicities caused by on-target off-tumor toxicities constitute major hurdles. Furthermore, the tumor microenvironment is usually characterized by chronic inflammation, the presence of immunosuppressive molecules, and immune cells that can reduce CAR T cell efficacy and facilitate antigen escape. Nonetheless, solid tumors are under investigation as possible targets despite their complexity, which represents a significant challenge. In preclinical mouse models, CAR T cells are able to efficiently recognize and kill several tumor xenografts. Overall, in the next few years, there will be intensive research into optimizing novel cell therapies to improve their effector functions and keep untoward effects in check. In this review, we provide an update on the state-of-the-art CAR T cell therapies in solid tumors, focusing on the preclinical studies and preliminary clinical findings aimed at developing optimal strategies to reduce toxicity and improve efficacy.

FOXP3+ regulatory T cells and the immune escape in solid tumours.

FOXP3+ regulatory T (Treg) cells play critical roles in establishing the immunosuppressive tumour microenvironment, which is achieved and dynamically maintained with the contribution of various stromal and immune cell subsets. However, the dynamics of non-lymphoid FOXP3+ Treg cells and the mutual regulation of Treg cells and other cell types in solid tumour microenvironment remains largely unclear. In this review, we summarize the latest findings on the dynamic connections and reciprocal regulations of non-lymphoid Treg cell subsets in accordance with well-established and new emerging hallmarks of cancer, especially on the immune escape of tumour cells in solid tumours. Our comprehension of the interplay between FOXP3+ Treg cells and key hallmarks of cancer may provide new insights into the development of next-generation engineered T cell-based immune treatments for solid tumours.

Hypoxia and ERα Transcriptional Crosstalk Is Associated with Endocrine Resistance in Breast Cancer.

Simple SummaryHormone receptor positive breast cancer patients are treated with anti-hormone molecules as a standard of care. However, resistance frequently occurs, leading to hormone resistant metastatic relapses in foreign organs. Understanding the molecular mechanisms through which breast cancer cells evade therapeutic pressure is of paramount interest. Hypoxia, which refers to oxygen deprivation and is characterized by the activation of hypoxia inducible factors, is a common feature of the solid tumor microenvironment, yet its influence on estrogen receptor alpha activity remains elusive. Here, we investigate the consequence of hypoxia and the signaling of hypoxia inducible factors on hormone responsiveness in breast cancer cells and its clinical implications.Estrogen receptor-alpha (ERα) is the driving transcription factor in 70% of breast cancers and its activity is associated with hormone dependent tumor cell proliferation and survival. Given the recurrence of hormone resistant relapses, understanding the etiological factors fueling resistance is of major clinical interest. Hypoxia, a frequent feature of the solid tumor microenvironment, has been described to promote endocrine resistance by triggering ERα down-regulation in both in vitro and in vivo models. Yet, the consequences of hypoxia on ERα genomic activity remain largely elusive. In the present study, transcriptomic analysis shows that hypoxia regulates a fraction of ERα target genes, underlying an important regulatory overlap between hypoxic and estrogenic signaling. This gene expression reprogramming is associated with a massive reorganization of ERα cistrome, highlighted by a massive loss of ERα binding sites. Profiling of enhancer acetylation revealed a hormone independent enhancer activation at the vicinity of genes harboring hypoxia inducible factor (HIFα) binding sites, the major transcription factors governing hypoxic adaptation. This activation counterbalances the loss of ERα and sustains hormone-independent gene expression. We describe hypoxia in luminal ERα (+) breast cancer as a key factor interfering with endocrine therapies, associated with poor clinical prognosis in breast cancer patients.

Oral administration of sodium bicarbonate can enhance the therapeutic outcome of Doxil® via neutralizing the acidic tumor microenvironment.

The pH of the tumor microenvironment in solid tumors is reported to be more acidic than that of normal tissues. The pH is controlled by over-expression of several transporters that are associated with the progression, angiogenesis, and metastasis of solid tumors. Antitumor effects of weak-base anticancer agents, such as doxorubicin (DXR), could be reduced in an acidic environment because of increases in the ionized form of the drug under these conditions, reducing its membrane penetrability. In our previous studies, we demonstrated that oral administration of sodium bicarbonate (NaHCO3) can neutralize the acidic tumor microenvironment and enhance the effects of small molecule anticancer drugs. However, it is not known whether or not increasing the tumor pH by oral administration of NaHCO3 leads to enhanced antitumor effects of lipidic nanoparticle formulations of weak-base anticancer drugs, such as Doxil®. In this study, we investigated the antitumor efficacy of Doxil® in combination with oral administration of NaHCO3 in a Colon26 tumor-bearing mouse model. NaHCO3 clearly enhanced the tumor-growth inhibitory effect of Doxil® without exacerbating any systemic side effects. In vitro studies indicated that high levels of DXR were internalized into cells at neutral pH. These studies demonstrate that the neutralization of acidic tumor microenvironment by an oral administration of NaHCO3 could be a promising approach to enhance the therapeutic outcomes of Doxil®.

10 Oral - CBX-12-101: A first-in-human study of CBX-12, an alphalex peptide drug conjugate (PDC) in patients with advanced or metastatic solid tumors

10 Oral - CBX-12-101: A first-in-human study of CBX-12, an alphalex peptide drug conjugate (PDC) in patients with advanced or metastatic solid tumors

339 (PB119) - An open-source, pathologist-in-the-loop workflow for quantitative and spatially-driven analysis of multiplexed immunohistochemistry images of the solid tumor microenvironment

With the recent technological advancements for highly multiplexed spatial imaging platforms, extensive studies have been performed to elucidate molecular landmarks of proliferation, immune invasion, hypoxia, and other attributes of the solid tumor microenvironment. However, many of the analysis pipelines for extracting quantitative information from these datasets offer limited windows for pathologists to interpret and provide biological meaning to results. We present an end-to-end workflow for quantitative analysis of tumor microenvironments, with an emphasis on using pathologists input for the classification of cells, quality control, and segmentation of microenvironmental structures.

41 (PB031) - CAR-T cell engineering strategies aimed at safe and effective targeting of solid tumors

Adoptive cell therapy based on chimeric antigen receptor-engineered T (CAR-T) cells has proven to be life-saving for many cancer patients. However, its therapeutic efficacy has so far been restricted to only a few malignancies, with solid tumors proving to be especially recalcitrant to efficient therapy. Poor intra-tumor infiltration by T cells and “T cell dysfunction” due to an immunosuppressive microenvironment are key barriers against CAR-T cell success against solid tumors. Furthermore, low level expression of CAR-directed tumor-associated antigens (TAA) in normal tissues can result in “on-target off-tumor” cytotoxicity, raising potential safety concerns. Using our best-in-class TALEN®-based gene editing platform, we present here innovative T cell engineering strategies that can combat some of the challenges posed by CAR-T cell development for solid tumors. These allogeneic ‘Smart CAR-T’ cells are designed to integrate locus-specific synthetic genes that respond to cues localized to the solid tumor microenvironment. The subsequent expression of these genes increases CAR-T cell persistence and anti-tumor activity while staying restricted to the tumor milieu. Thus, our proof-of-concept study demonstrates the feasibility of developing CAR-T cell engineering strategies that can improve solid tumor targeting while mitigating potential safety risks, encouraging us to bring them to the clinic. No conflict of interest.

Enforcing GLUT3 expression in CD8+ T cells improves fitness and tumor control by promoting glucose uptake and energy storage.

Despite the tremendous success of adoptive T-cell therapies (ACT) in fighting certain hematologic malignancies, not all patients respond, a proportion experience relapse, and effective ACT of most solid tumors remains elusive. In order to improve responses to ACT suppressive barriers in the solid tumor microenvironment (TME) including insufficient nutrient availability must be overcome. Here we explored how enforced expression of the high-affinity glucose transporter GLUT3 impacted tumor-directed T cells. Overexpression of GLUT3 in primary murine CD8+ T cells enhanced glucose uptake and increased glycogen and fatty acid storage, and was associated with increased mitochondrial fitness, reduced ROS levels, higher abundance of the anti-apoptotic protein Mcl-1, and better resistance to stress. Importantly, GLUT3-OT1 T cells conferred superior control of B16-OVA melanoma tumors and, in this same model, significantly improved survival. Moreover, a proportion of treated mice were cured and protected from re-challenge, indicative of long-term T cell persistence and memory formation. Enforcing expression of GLUT3 is thus a promising strategy to improve metabolic fitness and sustaining CD8+ T cell effector function in the context of ACT.

Ultrasound and laser-promoted dual-gas nano-generator for combined photothermal and immune tumor therapy.

The combination of photothermal therapy (PTT) and immune tumor therapy has emerged as a promising avenue for cancer treatment. However, the insufficient immune response caused by inefficient immunogenic cell death (ICD) inducers and thermal resistance, immunosuppression, and immune escape resulting from the hypoxic microenvironment of solid tumors severely limit its efficacy. Herein, we report an ultrasound and laser-promoted dual-gas nano-generator (calcium carbonate-polydopamine-manganese oxide nanoparticles, CPM NPs) for enhanced photothermal/immune tumor therapy through reprogramming tumor hypoxic microenvironment. In this system, CPM NPs undergo reactive decomposition in a moderately acidic tumor, resulting in the generation of calcium, manganese ions, carbon dioxide (CO2), and oxygen (O2). Calcium and manganese ions act as adjuvants that trigger an immune response. The cancer cell membrane rupture caused by sudden burst of bubbles (CO2 and O2) under ultrasound stimulation and the photothermal properties of PDA also contributed to the ICD effect. The generation of O2 alleviates tumor hypoxia and thus reduces hypoxia-induced heat resistance and immunosuppressive effects, thereby improving the therapeutic efficacy of combination PTT and immune therapy. The present study provides a novel approach for the fabrication of a safe and effective tumor treatment platform for future clinical applications.

Cancer Immunotherapies Based on Genetically Engineered Macrophages

Anticancer immunotherapies are therapeutics aimed at eliciting immune responses against tumor cells. Immunotherapies based on adoptive transfer of engineered immune cells have raised great hopes of cures because of the success of chimeric antigen receptor T-cell therapy in treating some hematologic malignancies. In parallel, advances in detailed analyses of the microenvironment of many solid tumors using high-dimensional approaches have established the origins and abundant presence of tumor-associated macrophages. These macrophages have an anti-inflammatory phenotype and promote tumor growth through a variety of mechanisms. Attempts have been made to engineer macrophages with chimeric receptors or transgenes to counteract their protumor activities and promote their antitumor functions such as phagocytosis of cancer cells, presentation of tumor antigens, and production of inflammatory cytokines. In this review, we cover current breakthroughs in engineering myeloid cells to combat cancer as well as potential prospects for myeloid-cell treatments.

Abstract 3 Generation of Myeloid Cells from Cord Blood-Derived CD34+ Cells for Therapeutic Intent

IntroductionMacrophages and monocytes traffic to and infiltrate complex solid tumor microenvironments where conditions can promote an immunosuppressive phenotype in resident tumor-associated macrophages that hinder effective anti-tumor immune responses. Ongoing advances in cell engineering are being adapted to modify monocytes and macrophages into efficacious anti-tumor cell therapies. However, a limiting factor to this promising therapy has been cell numbers, since monocytes obtained from adult peripheral blood mononuclear cells do not expand ex vivo.ObjectiveWe are developing an expanded allogeneic, cryopreserved, off-the-shelf myeloid cell product for the treatment of solid tumors.MethodsCD34+ cells isolated from pooled donor cord blood are the starting material for generation of myeloid cells. The process has three phases: (1) expansion of hematopoietic stem and progenitor cells, (2) continued expansion and differentiation into monocytes, and (3) differentiation of monocytes into mature macrophages. Cells are characterized before and after cryopreservation by immune phenotyping, morphology, and phagocytic capacity.ResultsThe current culture method produces several thousand HLA-DR+ CD11b+ myeloid cells at both the monocyte and macrophage stage per starting CD34+ cell. These cells make up ~70% of the final cell product along with a potentially beneficial heterogeneous mix of additional myeloid-derived cells. Immunophenotyping demonstrates expression of canonical monocyte/macrophage markers, including CD14, CD86, and CD163. Cell morphology after macrophage differentiation is similar to that of peripheral blood-derived mature adult macrophages. Importantly, the final cell product can be cryopreserved with excellent recovery of viable cells post-thaw that are functional, as demonstrated by maintenance of phagocytic potential when compared with pre-cryopreservation function.DiscussionThis proprietary CD34+ cell expansion and directed differentiation platform results in the generation of therapeutically relevant numbers of functional myeloid cells. Furthermore, the ability to cryopreserve these cells, with demonstrated viability and function upon thaw, facilitates their use as an off-the-shelf cell therapy, with potential for faster and less expensive routes to treatments for solid tumors that have proven resistant to other cell therapies. Additional work is being done toward engineering these myeloid cells to express proteins to enhance a patient’s anti-tumor immune responses, whether these cells are used alone or in combination with other therapeutics.

470P Preclinical assessment of the pharmacokinetics, disposition, and duration of action of the dual alphav-integrin and neuropilin-1 targeting peptide CEND-1

CEND-1 (iRGD), a bifunctional cyclic peptide, enhances delivery of co-administered anti-cancer agents by transforming the solid tumour microenvironment into a temporary drug conduit. The present study explored the pharmacokinetic (PK) properties of CEND-1, as well as its distribution, tumor selectivity and duration of action in preclinical tumor models.

Effect of pulsed field ablation on solid tumor cells and microenvironment.

Pulsed field ablation can increase membrane permeability and is an emerging non-thermal ablation. While ablating tumor tissues, electrical pulses not only act on the membrane structure of cells to cause irreversible electroporation, but also convert tumors into an immune active state, increase the permeability of microvessels, inhibit the proliferation of pathological blood vessels, and soften the extracellular matrix thereby inhibiting infiltrative tumor growth. Electrical pulses can alter the tumor microenvironment, making the inhibitory effect on the tumor not limited to short-term killing, but mobilizing the collective immune system to inhibit tumor growth and invasion together.

Supramolecular Nitric Oxide Depot for Hypoxic Tumor Vessel Normalization and Radiosensitization.

In cancer radiotherapy, the lack of fixed DNAdamage by oxygen in hypoxic microenvironment of solid tumors often leads to severe radioresistance. Nitric oxide (NO) is a potent radiosensitizer that acts in two ways. It can directly react with the radical DNA thus fixing the damage. It also normalizes the abnormal tumor vessels, thereby increasing blood perfusion and oxygen supply. To achieve these functions, the dosage and duration of NO treatment need to be carefully controlled, otherwise it will lead to the exact opposite outcomes. However, a delivery method that fulfills both requirements is still lacking. A NO depot is designed for the control of NO releasing both over quantity and duration for hypoxic tumor vessel normalization and radiosensitization. In B16-tumor-bearing mice, the depot can provide low dosage NO continuously and release large amount of NO immediately before irradiation for a short period of time. These two modes of treatment work in synergy to reverse the radioresistance of B16tumors more efficiently than releasing at single dosage.

Engineering H2 O2 and O2 Self-Supplying Nanoreactor to Conduct Synergistic Chemiexcited Photodynamic and Calcium-Overloaded Therapy in Orthotopic Hepatic Tumors.

Photodynamic therapy (PDT) is traditionally ineffective for deeply embedded tumors due to the poor penetration depth of the excitation light. Chemiluminescence resonance energy transfer (CRET) has emerged as a promising mode of PDT without external light. To date, related research has frequently used endogenous hydrogen peroxide (H2 O2 ) and oxygen (O2 ) inside the solid tumor microenvironment to trigger CRET-mediated PDT. Unfortunately, this significantly restricts treatment efficacy and the development of further biomedical applications because of the limited amounts of endogenous H2 O2 and O2 . Herein, a nanohybrid (mSiO2 /CaO2 /CPPO/Ce6: mSCCC) nanoparticle (NP) is designed to achieve synergistic CRET-mediated PDT and calcium (Ca2+ )-overload-mediated therapy. The calcium peroxide (CaO2 ) formed inside mesoporous SiO2 (mSC) with the inclusion of the chemiluminescent agent (CPPO) and photosensitizer (Ce6) self-supplies H2 O2 , O2 , and Ca2+ allowing for the subsequent treatments. The Ce6 in mSCCC NPs is excited by chemical energy in situ following the supply of H2 O2 and O2 to produce singlet oxygen (1 O2 ). The nanohybrid NPs are coated with stearic acid to avoid decomposition during blood circulation through contact with aqueous environment. This nanohybrid shows promising performance in the generation of 1 O2 for external light-free PDT and the release of Ca2+ ions for Ca2+ -overloaded therapy against orthotopic hepatocellular carcinoma.

Hypoxia-driven miR-1307–3p promotes hepatocellular carcinoma cell proliferation and invasion by modulating DAB2 interacting protein

Hypoxia is a common feature of the solid tumor microenvironment that is presented as poor clinical outcomes in multiple tumor types, including HCC. Hypoxia stabilizes HIF-1α/HIF-2α, which then moves into the nucleus and binds with HIF-1β to form a transcription complex, thereby promoting the transcription of target genes, including mRNAs, miRNAs and lncRNAs to exert their biological functions. Here, through a series of functional assay, including hypoxia culture, MTT, colony-formation, Transwell, qRT-PCR and western blot, we confirmed that miR-1307–3p, as a novel hypoxia-responsive factor, can be directly transcribed by HIF-1α rather than HIF-2α. Hypoxia-driven miR-1307–3p facilitated proliferation and invasion of HCC cells via repressing DAB2IP. Moreover, under hypoxia microenvironment, DAB2IP, as a direct target of miR-1307–3p, was down-regulated to activate AKT/mTOR signaling to further maintain the expression level of HIF-1α, thereby forming a feedback loop between HIF-1α/miR-1307–3p and DAB2IP. Targeting miR-1307–3p/DAB2IP axis also modulated tumor growth and metastasis in vivo. In summary, there exists a feedback loop between HIF-1α/miR-1307–3p and DAB2IP in HCC. Targeting a vicious feedback loop between HIF-1α/miR-1307–3p and DAB2IP may be a promising strategy to combat HCC.

Programmable therapeutic nanoscale covalent organic framework for photodynamic therapy and hypoxia-activated cascade chemotherapy

Clinical photodynamic therapy (PDT) only has a limited cancer therapeutic effect and typically leads to a more hypoxic milieu owing to the hypoxic conditions of the solid tumor microenvironment that limit the singlet oxygen (1O2), generation. To address this issue, the PDT, in combination with hypoxia-activated prodrugs, has recently been investigated as a possible clinical treatment modality for cancer therapy. By cross-linking the photosensitizer tetra(4-hydroxyphenyl)porphine (THPP) and a 1O2-cleavable thioketal (TK) linker, a multifunctional nanoscale covalent organic framework (COF) platform with a high porphyrin loading capacity was synthesized, which significantly improve the reactive oxygen species (ROS) generation efficiency and contributes to PDT. As-synthesized THPPTK-PEG nanoparticles (NPs) possess a high THPP photosensitizer content and mesoporous structure for further loading of the hypoxia-responsive prodrug banoxantrone (AQ4N) into the COF with a high-loading content. The nano-carriers surfaces are coated with a thick PEG coating to promote their dispersibility in physiological surroundings and therapeutic performance. When exposed to 660 nm radiation, such a nanoplatform can efficiently create cytotoxic 1O2 for PDT. Similarly, oxygen intake may exacerbate the hypoxic environment of the tumor, inducing the activation of AQ4N to achieve hypoxia-activated cascade chemotherapy and increased treatment efficacy. This study provides a new nanoplatform for photodynamic-chemical synergistic therapy and offers critical new insights for designing and developing a multifunctional supramolecular drug delivery system. Statement of significanceHere, we designed a laser-activated hypoxia-responsive nanoscale COF nanoplatform for hypoxia-activated cascade chemotherapy and PDT. When exposed to laser light, thus this nanoplatform can efficiently create cytotoxic 1O2 for PDT while consuming oxygen at the tumor location. However, increased oxygen consumption can exacerbate the tumor's hypoxic environment, causing AQ4N to become active, allowing for programmed hypoxia-triggered cascade chemotherapy and improved therapeutic efficacy. In addition, this innovative nanoscale COF nanoplatform allows for laser-controlled drug delivery in specific areas, which dramatically improves tumor inhibition. This research suggests a method for attaining ultrasensitive drug release and effective cascade therapy for cancer treatments.

Cancer-associated fibroblasts in the single-cell era.

Cancer-associated fibroblasts (CAFs) are central players in the microenvironment of solid tumors, affecting cancer progression and metastasis. CAFs have diverse phenotypes, origins and functions and consist of distinct subpopulations. Recent progress in single-cell RNA-sequencing technologies has enabled detailed characterization of the complexity and heterogeneity of CAF subpopulations in multiple tumor types. In this Review, we discuss the current understanding of CAF subsets and functions as elucidated by single-cell technologies, their functional plasticity, and their emergent shared and organ-specific features that could potentially be harnessed to design better therapeutic strategies for cancer.