Tumor necrosis factor receptor signaling is a driver of chronic lymphocytic leukemia that can be therapeutically targeted by the flavonoid wogonin

IL-1 receptor antagonism reveals a yin-yang relationship between NFκB and interferon signaling in chronic lymphocytic leukemia

Nuclear factor kappa B (NFκB) is a pathogenic factor in chronic lymphocytic leukemia (CLL) that is not addressed specifically by current therapies. NFκB is activated by inflammatory factors that stimulate toll-like receptors (TLRs) and receptors for interleukin-1 (IL-1) family members. IL-1 is considered a master regulator of inflammation, and IL-1 receptor signaling is inhibited by the IL-1 receptor antagonist anakinra. These considerations suggested that anakinra might have a role in the treatment of CLL. Consistent with this idea, anakinra inhibited spontaneous and TLR7-mediated activation of the canonical NFκB pathway in CLL cells in vitro. However, CLL cells exhibited only weak signaling responses to IL-1 itself, and anakinra was found to inhibit NFκB along with oxidative stress in an IL-1 receptor-independent manner. Anakinra was then administered with minimal toxicity to 11 previously untreated CLL patients in a phase I dose-escalation trial (NCT04691765). A stereotyped clinical response was observed in all patients. Anakinra lowered blood lymphocytes and lymph node sizes within the first month that were associated with downregulation of NFκB and oxidative stress in the leukemia cells. However, inhibition of NFκB was accompanied by upregulation of type 1 interferon (IFN) signaling, c-MYC-regulated genes and proteins, and loss of the initial clinical response. Anakinra increased IFN signaling and survival of CLL cells in vitro that were, respectively, phenocopied by mitochondrial antioxidants and reversed by IFN receptor blocking antibodies. These observations suggest that anakinra has activity in CLL and may be a useful adjunct for conventional therapies as long as compensatory IFN signaling is blocked at the same time.

On the mechanism of wogonin against acute monocytic leukemia using network pharmacology and experimental validation

Wogonin is a natural flavone compound from the plant Scutellaria baicalensis, which has a variety of pharmacological activities such as anti-cancer, anti-virus, anti-inflammatory, and immune regulation. However, the potential mechanism of wogonin remains unknown. This study was to confirm the molecular mechanism of wogonin for acute monocytic leukemia treatment, known as AML-M5. The potential action targets between wogonin and acute monocytic leukemia were predicted from databases. The compound-target-pathway network and protein-protein interaction network (PPI) were constructed. The enrichment analysis of related targets and molecular docking were performed. The network pharmacological results of wogonin for AML-M5 treatment were verified using the THP-1 cell line. 71 target genes of wogonin associated with AML-M5 were found. The key genes TP53, SRC, AKT1, RELA, HSP90AA1, JUN, PIK3R1, and CCND1 were preliminarily found to be the potential central targets of wogonin for AML-M5 treatment. The PPI network analysis, GO analysis and KEGG pathway enrichment analysis demonstrated that the PI3K/AKT signaling pathway was the significant pathway in the wogonin for AML-M5 treatment. The antiproliferative effects of wogonin on THP-1 cells of AML-M5 presented a dose-dependent and time-dependent manner, inducing apoptosis, blocking the cell cycle at the G2/M phase, decreasing the expressions of CCND1, CDK2, and CyclinA2 mRNA, as well as AKT and p-AKT proteins. The mechanisms of wogonin on AML-M5 treatment may be associated with inhibiting cell proliferation and regulating the cell cycle via the PI3K/AKT signaling pathway.

Factors associated with long-term outcomes of CD19 CAR T-cell therapy for relapsed/refractory CLL

High response rates have been reported after CD19-targeted chimeric antigen receptor-modified (CD19 CAR) T-cell therapy for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL), yet the factors associated with duration of response in this setting are poorly characterized. We analyzed long-term outcomes in 47 patients with R/R CLL and/or Richter transformation treated on our phase 1/2 clinical trial of CD19 CAR T-cell therapy with an updated median follow-up of 79.6 months. Median progression-free survival (PFS) was 8.9 months, and the 6-year PFS was 17.8%. Maximum standardized uptake value (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.07-1.23; P < .001) and bulky disease (≥5 cm; HR, 2.12; 95% CI, 1.06-4.26; P = .034) before lymphodepletion were associated with shorter PFS. Day +28 complete response by positron emission tomography-computed tomography (HR, 0.13; 95% CI, 0.04-0.40; P < .001), day +28 measurable residual disease (MRD) negativity by multiparameter flow cytometry (HR, 0.08; 95% CI, 0.03-0.22; P < .001), day +28 MRD negativity by next-generation sequencing (HR, 0.21; 95% CI, 0.08-0.51; P < .001), higher peak CD8+ CAR T-cell expansion (HR, 0.49; 95% CI; 0.36-0.68; P < .001), higher peak CD4+ CAR T-cell expansion (HR, 0.47; 95% CI; 0.33-0.69; P < .001), and longer CAR T-cell persistence (HR, 0.56; 95% CI, 0.44-0.72; P < .001) were associated with longer PFS. The 6-year duration of response and overall survival were 26.4% and 31.2%, respectively. CD19 CAR T-cell therapy achieved durable responses with curative potential in a subset of patients with R/R CLL. This trial was registered at www.clinicaltrials.gov as #NCT01865617.

Death of tonsillar B cells by NETosis

Regulating B cell death is essential for generating antibodies and maintaining immune tolerance. B cells can die by apoptosis, and we report that human tonsil B cells, but not peripheral blood B cells also die by NETosis. This cell death is density-dependent, characterized by the loss of cell and nuclear membrane integrity, release of reactive oxygen species, and chromatin decondensation. Tonsil B cells secrete high levels of TNF, and inhibiting TNF prevented chromatin decondensation. By in situ fluorescence microscopy, B cell NETosis, as identified by the hyper citrullination of Histone-3, was localized to the light zone (LZ) of germinal centers in normal tonsil and overlapped with the B cell marker CD19/IgM. We propose a model in which stimulation of B cells in the LZ induces NETosis, driven in part by TNF. We also provide evidence that NETosis of tonsil B cells may be inhibited by an unidentified factor in tonsil. The results describe a previously unidentified form of B cell death and suggest a new mechanism to maintain B cell homeostasis during immune responses.

The function of natural compounds in important anticancer mechanisms

The existence of malignant tumors has been a threat to human life, health, and safety. Although the rapid development of radiotherapy, drug therapy, surgery, and local therapy has improved the quality of life of tumor patients, there are still some risks. Natural compounds are widely used in cancer because they are easy to obtain, have a good curative effects and have no obvious side effects, and play a vital role in the prevention and treatment of various cancers. Phenolic, flavonoids, terpenoids, alkaloids, and other natural components of traditional Chinese medicine have certain anti-tumor activities, which can promote apoptosis, anti-proliferation, anti-metastasis, inhibit angiogenesis, change the morphology of cancer cells and regulate immune function, etc., and have positive effects on breast cancer, liver cancer, lung cancer, gastric cancer, rectal cancer and so on. To better understand the effects of natural compounds on cancer, this paper screened out four important pathways closely related to cancer, including cell death and immunogenic cell death, immune cells in the tumor microenvironment, inflammation and related pathways and tumor metastasis, and systematically elaborated the effects of natural compounds on cancer.

Advances in Anti-Cancer Activities of Flavonoids in Scutellariae radix: Perspectives on Mechanism

Despite encouraging progresses in the development of novel therapies, cancer remains the dominant cause of disease-related mortality and has become a leading economic and healthcare burden worldwide. Scutellariae radix (SR, Huangqin in Chinese) is a common herb used in traditional Chinese medicine, with a long history in treating a series of symptoms resulting from cancer, like dysregulated immune response and metabolic abnormalities. As major bioactive ingredients extracted from SR, flavonoids, including baicalein, wogonin, along with their glycosides (baicalin and wogonoside), represent promising pharmacological and anti-tumor activities and deserve extensive research attention. Emerging evidence has made great strides in elucidating the multi-targeting therapeutic mechanisms and key signaling pathways underlying the efficacious potential of flavonoids derived from SR in the field of cancer treatment. In this current review, we aim to summarize the pharmacological actions of flavonoids against various cancers in vivo and in vitro. Moreover, we also make a brief summarization of the endeavor in developing a drug delivery system or structural modification to enhance the bioavailability and biological activities of flavonoid monomers. Taken together, flavonoid components in SR have great potential to be developed as adjuvant or even primary therapies for the clinical management of cancers and have a promising prospect.

Natural Products and their Derivatives as Immune Check Point Inhibitors: Targeting Cytokine/Chemokine Signalling in Cancer

Cancer immunotherapy is the new generation and widely accepted form of tumour treatment. It is, however, associated with exclusive challenges which include organ-specific inflammation, and single-target strategies. Therefore, approaches that can enhance the efficiency of existing immunotherapies and expand their indications are required for the further development of immunotherapy. Natural products and medicines are stated to have this desired effect on cancer immunotherapy (adoptive immune-cells therapy, cancer vaccines, and immune-check point inhibitors). They refurbish the immunosuppressed tumour microenvironment, which is the primary location of interaction of tumour cells with the host immune system. Various immune cell subsets, via interaction with cytokine/chemokine receptors, are recruited into this microenvironment, and these subsets have roles in tumour progression and treatment responsiveness. This review summarises cytokine/chemokine signalling, types of cancer immunotherapy and the herbal medicine-derived natural products targeting cytokine/chemokines and immune checkpoints. These natural compounds possess immunomodulatory activities and exert their anti-tumour effect by either blocking the interaction or modulating the expression of the proteins linked with immune checkpoint signaling pathways. Some compounds also show a synergistic effect in combination with existing monoclonal antibody drugs to reverse the tumour microenvironment. Additionally, we have also reported some studies about the derivatives and formulations used to overcome the limitations of natural forms. This review can provide important insights for directing future research.

Modulation of TLR/NF-κB/NLRP Signaling by Bioactive Phytocompounds: A Promising Strategy to Augment Cancer Chemotherapy and Immunotherapy

Background

Tumors often progress to a more aggressive phenotype to resist drugs. Multiple dysregulated pathways are behind this tumor behavior which is known as cancer chemoresistance. Thus, there is an emerging need to discover pivotal signaling pathways involved in the resistance to chemotherapeutic agents and cancer immunotherapy. Reports indicate the critical role of the toll-like receptor (TLR)/nuclear factor-κB (NF-κB)/Nod-like receptor pyrin domain-containing (NLRP) pathway in cancer initiation, progression, and development. Therefore, targeting TLR/NF-κB/NLRP signaling is a promising strategy to augment cancer chemotherapy and immunotherapy and to combat chemoresistance. Considering the potential of phytochemicals in the regulation of multiple dysregulated pathways during cancer initiation, promotion, and progression, such compounds could be suitable candidates against cancer chemoresistance.

Objectives

This is the first comprehensive and systematic review regarding the role of phytochemicals in the mitigation of chemoresistance by regulating the TLR/NF-κB/NLRP signaling pathway in chemotherapy and immunotherapy.

Methods

A comprehensive and systematic review was designed based on Web of Science, PubMed, Scopus, and Cochrane electronic databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to include papers on TLR/NF-κB/NLRP and chemotherapy/immunotherapy/chemoresistance by phytochemicals.

Results

Phytochemicals are promising multi-targeting candidates against the TLR/NF-κB/NLRP signaling pathway and interconnected mediators. Employing phenolic compounds, alkaloids, terpenoids, and sulfur compounds could be a promising strategy for managing cancer chemoresistance through the modulation of the TLR/NF-κB/NLRP signaling pathway. Novel delivery systems of phytochemicals in cancer chemotherapy/immunotherapy are also highlighted.

Conclusion

Targeting TLR/NF-κB/NLRP signaling with bioactive phytocompounds reverses chemoresistance and improves the outcome for chemotherapy and immunotherapy in both preclinical and clinical stages.

A systems genetics approach delineates the role of Bcl2 in leukemia pathogenesis

Leukemia is a group of malignancies of the blood forming tissues, and is characterized by the uncontrolled proliferation of blood cells. In the United States, it accounts for approximately 3.5% and 4% of all cancer-related incidences and mortalities, respectively. The current study aimed to explore the role of Bcl2 and associated genes in leukemia pathogenesis using a systems genetics approach. The transcriptome data from BXD Recombinant Inbred (RI) mice was analyzed to identify the expression of Bcl2 in myeloid cells. eQTL mapping was performed to select the potential chromosomal region and subsequently identify the candidate gene modulating the expression of Bcl2. Furthermore, gene enrichment and protein-protein interaction (PPI) analyses of the Bcl2-coexpressed genes were performed to demonstrate the role of Bcl2 in leukemia pathogenesis. The Bcl2-coexpressed genes were found to be enriched in various hematopoietic system related functions, and multiple pathways related to signaling, immune response, and cancer. The PPI network analysis demonstrated direct interaction of hematopoietic function related genes, such as Bag3, Bak1, Bcl2l11, Bmf, Mapk9, Myc, Ppp2r5c, and Ppp3ca with Bcl2. The eQTL mapping identified a 4.5 Mb genomic region on chromosome 11, potentially regulating the expression of Bcl2. A multi-criteria filtering process identified Top2a, among the genes located in the mapped locus, as the best candidate upstream regulator for Bcl2 expression variation. Hence, the current study provides better insights into the role of Bcl2 in leukemia pathogenesis and demonstrates the significance of our approach in gaining new knowledge on leukemia. Furthermore, our findings from the PPI network analysis and eQTL mapping provide supporting evidence of leukemia-associated genes, which can be further explored for their functional importance in leukemia. DATA AVAILABILITY: The myeloid cell transcriptomic data of the BXD mice used in this study can be accessed through our GeneNetwork (http://www.genenetwork.org) with the accession number of GN144.

IL-10 Rescues CLL Survival through Repolarization of Inflammatory Nurse-like Cells

Simple Summary

In in vitro co-cultures of CLL cells and nurse-like cells (NLC), protection against apoptosis is only provided by M2-like NLC, and not M1-like NLC. In this study, we propose that fine-tuning of NLC polarization (and therefore survival of leukemic cells) is dictated by a balance between IL-10 and TNF.

Abstract

Tumor-associated macrophages (TAMs) in chronic lymphocytic leukemia (CLL) are also called nurse-like cells (NLC), and confer survival signals through the release of soluble factors and cellular contacts. While in most patient samples the presence of NLC in co-cultures guarantees high viability of leukemic cells in vitro, in some cases this protective effect is absent. These macrophages are characterized by an “M1-like phenotype”. We show here that their reprogramming towards an M2-like phenotype (tumor-supportive) with IL-10 leads to an increase in leukemic cell survival. Inflammatory cytokines, such as TNF, are also able to depolarize M2-type protective NLC (decreasing CLL cell viability), an effect which is countered by IL-10 or blocking antibodies. Interestingly, both IL-10 and TNF are implied in the pathophysiology of CLL and their elevated level is associated with bad prognosis. We propose that the molecular balance between these two cytokines in CLL niches plays an important role in the maintenance of the protective phenotype of NLCs, and therefore in the survival of CLL cells.

Myeloid-derived suppressor cell subtypes differentially influence T-cell function, T-helper subset differentiation, and clinical course in CLL

Cancer pathogenesis involves the interplay of tumor- and microenvironment-derived stimuli. Here we focused on the influence of an immunomodulatory cell type, myeloid-derived suppressor cells (MDSCs), and their lineage-related subtypes on autologous T lymphocytes. Although MDSCs as a group correlated with an immunosuppressive Th repertoire and worse clinical course, MDSC subtypes (polymorphonuclear, PMN-MDSC, and monocytic, M-MDSCs) were often functionally discordant. In vivo, PMN-MDSCs existed in higher numbers, correlated with different Th-subsets, and more strongly associated with poor clinical course than M-MDSCs. In vitro, PMN-MDSCs were more efficient at blocking T-cell growth and promoted Th17 differentiation. Conversely, in vitro M-MDSCs varied in their ability to suppress T-cell proliferation, due to the action of TNFα, and promoted a more immunostimulatory Th compartment. Ibrutinib therapy impacted MDSCs differentially as well, since after initiating therapy, PMN-MDSC numbers progressively declined, whereas M-MDSC numbers were unaffected, leading to a set of less immunosuppressive Th cells. Consistent with this, clinical improvement based on decreasing CLL-cell numbers correlated with the decrease in PMN-MDSCs. Collectively, the data support a balance between PMN-MDSC and M-MDSC numbers and function influencing CLL disease course.

LW-213 induces cell apoptosis in human cutaneous T-cell lymphomas by activating PERK-eIF2α-ATF4-CHOP axis

Cutaneous T-cell lymphoma (CTCL) is characterized by a heterogeneous group of extranodal non-Hodgkin lymphomas, in which monoclonal T lymphocytes infiltrate the skin. LW-213, a derivative of wogonin, was found to induce cell apoptosis in chronic myeloid leukemia (CML). In this study, we investigated the effects of LW-213 on CTCL cells and the underlying mechanisms. We showed that LW-213 (1-25 μM) dose-dependently inhibited human CTCL cell lines (Hut-102, Hut-78, MyLa, and HH) with IC₅₀ values of around 10 μM, meanwhile it potently inhibited primary leukemia cells derived from peripheral blood of T-cell lymphoma patients. We revealed that LW-213-induced apoptosis was accompanied by ROS formation and the release of calcium from endoplasmic reticulum (ER) through IP₃R-1channel. LW-213 selectively activated CHOP and induced apoptosis in Hut-102 cells via activating PERK-eIF2α-ATF4 pathway. Interestingly, the degree of apoptosis and expression of ER stress-related proteins were alleviated in the presence of either N-acetyl cysteine (NAC), an ROS scavenger, or 2-aminoethyl diphenylborinate (2-APB), an IP₃R-1 inhibitor, implicating ROS/calcium-dependent ER stress in LW-213-induced apoptosis. In NOD/SCID mice bearing Hut-102 cell line xenografts, administration of LW-213 (10 mg/kg, ip, every other day for 4 weeks) markedly inhibited the growth of Hut-102 derived xenografts and prolonged survival. In conclusion, our study provides a new insight into the mechanism of LW-213-induced apoptosis, suggesting the potential of LW-213 as a promising agent against CTCL.

Chronic lymphocytic leukemia B-cell-derived TNFα impairs bone marrow myelopoiesis

TNFα is implicated in chronic lymphocytic leukemia (CLL) immunosuppression and disease progression. TNFα is constitutively produced by CLL B cells and is a negative regulator of bone marrow (BM) myelopoiesis. Here, we show that co-culture of CLL B cells with purified normal human hematopoietic stem and progenitor cells (HSPCs) directly altered protein levels of the myeloid and erythroid cell fate determinants PU.1 and GATA-2 at the single-cell level within transitional HSPC subsets, mimicking ex vivo expression patterns. Physical separation of CLL cells from control HSPCs or neutralizing TNFα abrogated upregulation of PU.1, yet restoration of GATA-2 required TNFα neutralization, suggesting both cell contact and soluble-factor-mediated regulation. We further show that CLL patient BM myeloid progenitors are diminished in frequency and function, an effect recapitulated by chronic exposure of control HSPCs to low-dose TNFα. These findings implicate CLL B-cell-derived TNFα in impaired BM myelopoiesis.

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CLL patient BM HSPCs exhibit aberrant molecular and functional characteristics

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CLL B-cell-derived TNFα upregulates PU.1 and GATA-2 in BM HSPCs

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The effects of CLL B-cell-derived TNFα are reversible upon TNFα neutralization

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Chronic TNFα exposure in vitro recapitulates ex vivo HSPC functional deficiencies

Natural products and their derivatives: Promising modulators of tumor immunotherapy

A wealth of evidence supports the role of tumor immunotherapy as a vital therapeutic option in cancer. In recent decades, accumulated studies have revealed the anticancer activities of natural products and their derivatives. Increasing interest has been driven toward finding novel potential modulators of tumor immunotherapy from natural products, a hot research topic worldwide. These works of research mainly focused on natural products, including polyphenols (e.g., curcumin, resveratrol), cardiotonic steroids (e.g., bufalin and digoxin), terpenoids (e.g., paclitaxel and artemisinins), and polysaccharide extracts (e.g., lentinan). Compelling data highlight that natural products have a promising future in tumor immunotherapy. Considering the importance and significance of this topic, we initially discussed the integrated research progress of natural products and their derivatives, including target T cells, macrophages, B cells, NKs, regulatory T cells, myeloid‐derived suppressor cells, inflammatory cytokines and chemokines, immunogenic cell death, and immune checkpoints. Furthermore, these natural compounds inactivate several key pathways, including NF‐κB, PI3K/Akt, MAPK, and JAK/STAT pathways. Here, we performed a deep generalization, analysis, and summarization of the previous achievements, recent progress, and the bottlenecks in the development of natural products as tumor immunotherapy. We expect this review to provide some insight for guiding future research.

Increased levels of the cardiovascular disease risk biomarkers GDF15 and myostatin in patients with chronic lymphocytic leukemia

Individuals suffering from cancer, including hematological malignancies, are at increased risk of cardiovascular disease (CVD). Elevated levels of several biomarkers in blood are associated with an increased risk of CVD. The aim of this study was to investigate whether a subset of such CVD risk biomarkers was elevated in patients with untreated chronic lymphocytic leukemia (CLL). Blood plasma and serum from 139 CLL patients and 71 healthy age-matched controls were analyzed for 11 proposed CVD risk biomarkers. The CLL cohort displayed a more heterogeneous pattern of biomarker expression compared to controls. The majority, eight out of 11, analyzed CVD risk biomarkers differed significantly in concentrations between CLL patients and controls. Increased levels of the biomarkers GDF15 and myostatin have not previously been reported in CLL. Further prospective studies are warranted to investigate whether these biomarkers predict future cardiovascular events in patients with CLL.

Ibrutinib in Chronic Lymphocytic Leukemia: Clinical Applications, Drug Resistance, and Prospects

Bruton’s tyrosine kinase (BTK), a pivotal component of B-cell receptor (BCR) signaling, has been recognized as an important driver of the pathogenesis of chronic lymphocytic leukemia. Ibrutinib is a highly active and selectively irreversible inhibitor of BTK, which has been approved to be effective in both frontline and recurrent therapy of CLL. Acquired resistance has become a greater problem than initially anticipated with the widespread use of ibrutinib. An ongoing exploration of the mechanisms of ibrutinib resistance (IR) in CLL has revealed potentially useful therapeutic targets. New drugs expected to overcome IR in CLL are in the early stages of clinical development. This study aimed to summarize the possible mechanisms of IR and retrospectively analyze promising therapies that might have superior efficacy in overcoming IR.

Clinico-Biological Implications of Modified Levels of Cytokines in Chronic Lymphocytic Leukemia: A Possible Therapeutic Role

B-cell chronic lymphocytic leukemia (B-CLL) is the main cause of mortality among hematologic diseases in Western nations. B-CLL is correlated with an intense alteration of the immune system. The altered functions of innate immune elements and adaptive immune factors are interconnected in B-CLL and are decisive for its onset, evolution, and therapeutic response. Modifications in the cytokine balance could support the growth of the leukemic clone via a modulation of cellular proliferation and apoptosis, as some cytokines have been reported to be able to affect the life of B-CLL cells in vivo. In this review, we will examine the role played by cytokines in the cellular dynamics of B-CLL patients, interpret the contradictions sometimes present in the literature regarding their action, and evaluate the possibility of manipulating their production in order to intervene in the natural history of the disease.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

Numerous natural products originated from Chinese herbal medicine exhibit anti-cancer activities, including anti-proliferative, pro-apoptotic, anti-metastatic, anti-angiogenic effects, as well as regulate autophagy, reverse multidrug resistance, balance immunity, and enhance chemotherapy in vitro and in vivo. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2011) on the key compounds with anti-cancer effects derived from Chinese herbal medicine (curcumin, epigallocatechin gallate, berberine, artemisinin, ginsenoside Rg3, ursolic acid, silibinin, emodin, triptolide, cucurbitacin B, tanshinone I, oridonin, shikonin, gambogic acid, artesunate, wogonin, β-elemene, and cepharanthine) in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we focused on their recently discovered and/or investigated pharmacological effects, novel mechanism of action, relevant clinical studies, and their innovative applications in combined therapy and immunomodulation. In addition, the present review has extended to describe other promising compounds including dihydroartemisinin, ginsenoside Rh2, compound K, cucurbitacins D, E, I, tanshinone IIA and cryptotanshinone in view of their potentials in cancer therapy. Up to now, the evidence about the immunomodulatory effects and clinical trials of natural anti-cancer compounds from Chinese herbal medicine is very limited, and further research is needed to monitor their immunoregulatory effects and explore their mechanisms of action as modulators of immune checkpoints.

IGF1R as druggable target mediating PI3K-δ inhibitor resistance in a murine model of chronic lymphocytic leukemia

Targeted therapy is revolutionizing the treatment of cancers, but resistance evolves against these therapies and derogates their success. The phosphatidylinositol 3-kinase delta (PI3K-δ) inhibitor idelalisib has been approved for treatment of chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma, but the mechanisms conferring resistance in a subset of patients are unknown. Here, we modeled resistance to PI3K-δ inhibitor in vivo using a serial tumor transfer and treatment scheme in mice. Whole-exome sequencing did not identify any recurrent mutation explaining resistance to PI3K-δ inhibitor. In the murine model, resistance to PI3K-δ inhibitor occurred as a result of a signaling switch mediated by consistent and functionally relevant activation of insulin-like growth factor 1 receptor (IGF1R), resulting in enhanced MAPK signaling in the resistant tumors. Overexpression of IGF1R in vitro demonstrated its prominent role in PI3K-δ inhibitor resistance. IGF1R upregulation in PI3K-δ inhibitor-resistant tumors was mediated by functional activation and enhanced nuclear localization of forkhead box protein O1 transcription factors and glycogen synthase kinase 3β. In human CLL, high IGF1R expression was associated with trisomy 12. CLL cells from an idelalisib-treated patient showed decreased sensitivity to idelalisib in vitro concomitant with enhanced MAPK signaling and strong upregulation of IGF1R upon idelalisib exposure. Thus, our results highlight that alternative signaling cascades play a predominant role in the resistance and survival of cancer cells under PI3K-δ inhibition. We also demonstrate that these pathway alterations can serve as therapeutic targets, because inhibition of IGF1R offered efficacious salvage treatment of PI3K-δ inhibitor-resistant tumors in vitro and in vivo.