Mechanisms of Lymphoma Clearance Induced by High-Dose Alkylating Agents

Empowering macrophages: the cancer fighters within the tumour microenvironment in mantle cell lymphoma

In Mantle Cell Lymphoma (MCL), the role of macrophages within the tumour microenvironment (TME) has recently gained attention due to their impact on prognosis and response to therapy. Despite their low absolute number in MCL tumour tissue, recent findings reveal an association between the levels of macrophages and prognosis, consistent with trends observed in other lymphoma subtypes. M2-like macrophages, identified by markers such as CD163, contribute to angiogenesis and suppression of the immune response. Clinical trials with MCL patients treated with chemoimmunotherapy and targeted treatments underscore the adverse impact of high levels of M2-like macrophages. Immunomodulatory drugs like lenalidomide reduce the levels of MCL-associated CD163+ macrophages and enhance macrophage phagocytic activity. Similarly, clinical approaches targeting the CD47 "don't eat me" signalling, in combination with the anti-CD20-antibody rituximab, demonstrate increased macrophage activity and phagocytosis of MCL tumour cells. Cell-based therapies such as chimeric antigen receptor (CAR) T-cell have shown promise but various challenges persist, leading to a potential interest in CAR-macrophages (CAR-M). When macrophages are recruited to the TME, they offer advantages including phagocytic function and responsiveness to microenvironment alterations, suggesting their potential as a manipulable and inducible alternative when CAR T-cell therapies fails in the complex landscape of MCL treatment.

Adverse clinical outcomes and immunosuppressive microenvironment of RHO-GTPase activation pattern in hepatocellular carcinoma

BACKGROUND

Emerging evidence suggests that Rho GTPases play a crucial role in tumorigenesis and metastasis, but their involvement in the tumor microenvironment (TME) and prognosis of hepatocellular carcinoma (HCC) is not well understood.

METHODS

We aim to develop a tumor prognosis prediction system called the Rho GTPases-related gene score (RGPRG score) using Rho GTPase signaling genes and further bioinformatic analyses.

RESULTS

Our work found that HCC patients with a high RGPRG score had significantly worse survival and increased immunosuppressive cell fractions compared to those with a low RGPRG score. Single-cell cohort analysis revealed an immune-active TME in patients with a low RGPRG score, with strengthened communication from T/NK cells to other cells through MIF signaling networks. Targeting these alterations in TME, the patients with high RGPRG score have worse immunotherapeutic outcomes and decreased survival time in the immunotherapy cohort. Moreover, the RGPRG score was found to be correlated with survival in 27 other cancers. In vitro experiments confirmed that knockdown of the key Rho GTPase-signaling biomarker SFN significantly inhibited HCC cell proliferation, invasion, and migration.

CONCLUSIONS

This study provides new insight into the TME features and clinical use of Rho GTPase gene pattern at the bulk-seq and single-cell level, which may contribute to guiding personalized treatment and improving clinical outcome in HCC.

Modeling the crosstalk between malignant B cells and their microenvironment in B-cell lymphomas: challenges and opportunities

B-cell lymphomas are a group of heterogeneous neoplasms resulting from the clonal expansion of mature B cells arrested at various stages of differentiation. Specifically, two lymphoma subtypes arise from germinal centers (GCs), namely follicular lymphoma (FL) and GC B-cell diffuse large B-cell lymphoma (GCB-DLBCL). In addition to recent advances in describing the genetic landscape of FL and GCB-DLBCL, tumor microenvironment (TME) has progressively emerged as a central determinant of early lymphomagenesis, subclonal evolution, and late progression/transformation. The lymphoma-supportive niche integrates a dynamic and coordinated network of immune and stromal cells defining microarchitecture and mechanical constraints and regulating tumor cell migration, survival, proliferation, and immune escape. Several questions are still unsolved regarding the interplay between lymphoma B cells and their TME, including the mechanisms supporting these bidirectional interactions, the impact of the kinetic and spatial heterogeneity of the tumor niche on B-cell heterogeneity, and how individual genetic alterations can trigger both B-cell intrinsic and B-cell extrinsic signals driving the reprogramming of non-malignant cells. Finally, it is not clear whether these interactions might promote resistance to treatment or, conversely, offer valuable therapeutic opportunities. A major challenge in addressing these questions is the lack of relevant models integrating tumor cells with specific genetic hits, non-malignant cells with adequate functional properties and organization, extracellular matrix, and biomechanical forces. We propose here an overview of the 3D in vitro models, xenograft approaches, and genetically-engineered mouse models recently developed to study GC B-cell lymphomas with a specific focus on the pros and cons of each strategy in understanding B-cell lymphomagenesis and evaluating new therapeutic strategies.

Antibody-mediated phagocytosis in cancer immunotherapy

Unconjugated monoclonal antibodies (mAb) have revolutionized the treatment of many types of cancer. Some of these mAbs promote the clearance of malignant cells via direct cytotoxic effects. More recently, antibody-dependent cellular phagocytosis (ADCP) has been appreciated as a major mechanism of action for a number of widely-used mAbs, including anti-CD20 (rituximab, obinutuzumab), anti-HER2 (trazituzumab), and anti-CD38 (daratumumab). However, as a monotherapy these ADCP-inducing mAbs produce insufficient levels of cytotoxicity in vivo and are not curative. As a result, these mAbs are most effectively used in combination therapies. The efficacy of these mAbs is further hampered by the apparent development of drug resistance by many patients. Here we will explore the role of ADCP in cancer immunotherapy and discuss the key factors that could limit the efficacy of ADCP-inducing mAbs in vivo. Finally, we will discuss current insights and approaches being applied to overcome these limitations.

Advances in single-cell RNA sequencing and its applications in cancer research

Cancers are a group of heterogeneous diseases characterized by the acquisition of functional capabilities during the transition from a normal to a neoplastic state. Powerful experimental and computational tools can be applied to elucidate the mechanisms of occurrence, progression, metastasis, and drug resistance; however, challenges remain. Bulk RNA sequencing techniques only reflect the average gene expression in a sample, making it difficult to understand tumor heterogeneity and the tumor microenvironment. The emergence and development of single-cell RNA sequencing (scRNA-seq) technologies have provided opportunities to understand subtle changes in tumor biology by identifying distinct cell subpopulations, dissecting the tumor microenvironment, and characterizing cellular genomic mutations. Recently, scRNA-seq technology has been increasingly used in cancer studies to explore tumor heterogeneity and the tumor microenvironment, which has increased the understanding of tumorigenesis and evolution. This review summarizes the basic processes and development of scRNA-seq technologies and their increasing applications in cancer research and clinical practice.

The Role of Macrophage Populations in Skeletal Muscle Insulin Sensitivity: Current Understanding and Implications

Insulin resistance is a crucial factor in the development of type 2 diabetes mellitus (T2DM) and other metabolic disorders. Skeletal muscle, the body's largest insulin-responsive tissue, plays a significant role in the pathogenesis of T2DM due to defects in insulin signaling. Recently, there has been growing evidence that macrophages, immune cells essential for tissue homeostasis and injury response, also contribute to the development of skeletal muscle insulin resistance. This review aims to summarize the current understanding of the role of macrophages in skeletal muscle insulin resistance. Firstly, it provides an overview of the different macrophage populations present in skeletal muscle and their specific functions in the development of insulin resistance. Secondly, it examines the underlying mechanisms by which macrophages promote or alleviate insulin resistance in skeletal muscle, including inflammation, oxidative stress, and altered metabolism. Lastly, the review discusses potential therapeutic strategies targeting macrophages to improve skeletal muscle insulin sensitivity and metabolic health.

Macrophage Involvement in Aging-Associated Skeletal Muscle Regeneration

The skeletal muscle is a dynamic organ composed of contractile muscle fibers, connective tissues, blood vessels and nerve endings. Its main function is to provide motility to the body, but it is also deeply involved in systemic metabolism and thermoregulation. The skeletal muscle frequently encounters microinjury or trauma, which is primarily repaired by the coordinated actions of muscle stem cells (satellite cells, SCs), fibro-adipogenic progenitors (FAPs), and multiple immune cells, particularly macrophages. During aging, however, the capacity of skeletal muscle to repair and regenerate declines, likely contributing to sarcopenia, an age-related condition defined as loss of muscle mass and function. Recent studies have shown that resident macrophages in skeletal muscle are highly heterogeneous, and their phenotypes shift during aging, which may exacerbate skeletal muscle deterioration and inefficient regeneration. In this review, we highlight recent insight into the heterogeneity and functional roles of macrophages in skeletal muscle regeneration, particularly as it declines with aging.

Immune priming with avelumab and rituximab prior to R-CHOP in diffuse large B-cell lymphoma: the phase II AvR-CHOP study

Immune evasion, due to abnormal expression of programmed-death ligands 1 and 2 (PD-L1/PD-L2), predicts poor outcomes with chemoimmunotherapy in diffuse large B-cell lymphoma (DLBCL). Immune checkpoint inhibition (ICI) has limited efficacy at relapse but may sensitise relapsed lymphoma to subsequent chemotherapy. ICI delivery to immunologically intact patients may thus be the optimal use of this therapy. In the phase II AvR-CHOP study, 28 patients with treatment-naive stage II-IV DLBCL received sequential avelumab and rituximab priming ("AvRp;" avelumab 10 mg/kg and rituximab 375 mg/m2 2-weekly for 2 cycles), R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone for 6 cycles) and avelumab consolidation (10 mg/kg 2-weekly for 6 cycles). Grade 3/4 immune-related adverse events occurred in 11%, meeting the primary endpoint of a grade ≥3 irAE rate of <30%. R-CHOP delivery was not compromised but one patient ceased avelumab. Overall response rates (ORR) after AvRp and R-CHOP were 57% (18% CR) and 89% (all CR). High ORR to AvRp was observed in primary mediastinal B-cell lymphoma (67%; 4/6) and molecularly-defined EBV-positive DLBCL (100%; 3/3). Progression during AvRp was associated with chemorefractory disease. Two-year failure-free and overall survival were 82% and 89%. An immune priming strategy with AvRp, R-CHOP and avelumab consolidation shows acceptable toxicity with encouraging efficacy.

Melittin-Carrying Nanoparticle Suppress T Cell-Driven Immunity in a Murine Allergic Dermatitis Model

Allergic contact dermatitis (ACD) and atopic dermatitis (AD) are the most common human skin disorders. Although corticosteroids have been widely used to treat ACD and AD, the side effects of corticosteroids encourage researchers to explore new immunoregulatory treatments. Here, an immunomodulatory approach based on lipid nanoparticles carrying α-helical configurational melittin (α-melittin-NP) is developed to overcome T cell-mediated inflammatory reactions in an oxazolone (OXA)-induced contact hypersensitivity mouse model and OXA-induced AD-like mouse model. Intradermal injection of low-dose α-melittin-NPs prevents the skin damage caused by melittin administration alone and efficiently targeted lymph nodes. Importantly, melittin and α-melittin-NPs restrain RelB activity in dendritic cells (DCs) and further suppresses dendritic cell activation and maturation in lymph nodes. Furthermore, low-dose α-melittin-NPs leads to relief of antigen recognition-induced effector T cell arrest in the dermis and inhibited allergen-specific T cell proliferation and activation. Significantly, this approach successfully controls Th1-type cytokine release in the ACD model and restricts Th2-type cytokine and IgE release in the AD-like model. Overall, intradermal delivery of low-dose α-melittin-NPs efficiently elicits immunosuppression against T cell-mediated immune reactions, providing a promising therapeutic strategy for treating skin disorders not restricted to the lesion region.

Targeting tumor-associated macrophages for cancer immunotherapy

Tumor-associated macrophages (TAMs) are one of the most abundant immune components in the tumor microenvironment and play a plethora of roles in regulating tumorigenesis. Therefore, the therapeutic targeting of TAMs has emerged as a new paradigm for immunotherapy of cancer. Herein, the review summarizes the origin, polarization, and function of TAMs in the progression of malignant diseases. The understanding of such knowledge leads to several distinct therapeutic strategies to manipulate TAMs to battle cancer, which include those to reduce TAM abundance, such as depleting TAMs or inhibiting their recruitment and differentiation, and those to harness or boost the anti-tumor activities of TAMs such as blocking phagocytosis checkpoints, inducing antibody-dependent cellular phagocytosis, and reprogramming TAM polarization. In addition, modulation of TAMs may reshape the tumor microenvironment and therefore synergize with other cancer therapeutics. Therefore, the rational combination of TAM-targeting therapeutics with conventional therapies including radiotherapy, chemotherapy, and other immunotherapies is also reviewed. Overall, targeting TAMs presents itself as a promising strategy to add to the growing repertoire of treatment approaches in the fight against cancer, and it is hopeful that these approaches currently being pioneered will serve to vastly improve patient outcomes and quality of life.

Interferon-a potentiates anti-PD-1 efficacy by remodeling glucose metabolism in the hepatocellular carcinoma microenvironment

The overall response rate for anti-PD-1 therapy remains modest in hepatocellular carcinoma (HCC). We found that a combination of interferon alpha (IFN-a) and anti-PD-1-based immunotherapy resulted in enhanced antitumor activity in unresectable HCC patients. In both immunocompetent orthotopic and spontaneous HCC models, IFN-a therapy synergized with anti-PD-1 and the combination treatment led to significant enrichment of cytotoxic CD27+ CD8+ T cells. Mechanistically, IFN-a suppressed HIF1a signaling by inhibiting FosB transcription in HCC cells, resulting in reduced glucose consumption capacity and consequentially establishing the high-glucose microenvironment that fostered transcription of the T cell costimulatory molecule Cd27 via mTOR-FOXM1 signaling in infiltrating CD8+ T cells. Together, these data reveal that IFN-a reprograms glucose metabolism within HCC tumor microenvironment, thereby liberating T cell cytotoxic capacities and potentiating the PD-1 blockade-induced immune response. Our findings suggest that IFN-a and anti-PD-1 cotreatment is an effective novel combination strategy for HCC patients.

Extracellular vesicles and PDL1 suppress macrophages inducing therapy resistance in TP53-deficient B-cell malignancies

Genetic alterations in the DNA Damage Response (DDR) pathway are a frequent mechanism of resistance to CIT in B-cell malignancies. We have previously shown that the synergy of CIT relies on secretory crosstalk elicited by chemotherapy between the tumour cells and macrophages. Here, we show that loss of multiple different members of the DDR pathway inhibits macrophage phagocytic capacity in vitro and in vivo. Particularly loss of TP53 led to decreased phagocytic capacity ex vivo across multiple B-cell malignancies. We demonstrate via in vivo cyclophosphamide treatment using the Eµ-TCL1 mouse model that loss of macrophage phagocytic capacity in Tp53-deleted leukemia is driven by a significant downregulation of a phagocytic transcriptomic signature using scRNA-Seq. By analysing the tumour B-cell proteome, we identified a TP53 specific upregulation of proteins associated with extracellular vesicles (EV). We abrogated EV biogenesis in tumour B-cells via CRISPR-knockout (KO) of RAB27A and confirmed that the EVs from TP53-deleted lymphoma cells were responsible for the reduced phagocytic capacity and the in vivo CIT resistance. Furthermore, we observed that TP53 loss led to an upregulation of both PD-L1 cell surface expression and secretion of EVs by lymphoma cells. Disruption of EV bound PD-L1 by anti-PD-L1 antibodies or PD-L1 CRISPR-KO improved macrophage phagocytic capacity and in vivo therapy response. Thus, we demonstrate enhanced EV-release and increased PD-L1 expression in TP53-deficient B-cell lymphomas as novel mechanisms of macrophage function alteration in CIT resistance. This study indicates the use of checkpoint inhibition in the combination treatment of B-cell malignancies with TP53 loss.

Coadministration with bendamustine restores the antitumor activity of obinutuzumab in obinutuzumab-resistant tumors

BACKGROUND

The glycoengineered, humanized anti-CD20 antibody obinutuzumab is indicated for previously untreated or relapsed/refractory CD20-positive follicular lymphoma (FL). However, the effectiveness of obinutuzumab retreatment in relapsed/refractory FL after prior obinutuzumab-containing therapy is unclear. To address this issue, we investigated the antitumor activity of obinutuzumab plus bendamustine in obinutuzumab-resistant tumors established from a human non-Hodgkin lymphoma xenograft model.

MATERIALS AND METHODS

Obinutuzumab-resistant tumors (SU-DHL-4-OR-18-8) were established from an SU-DHL-4 xenograft model by repeated administration of obinutuzumab. Antitumor activity was evaluated based on tumor volume after treatment with obinutuzumab on Day 1, 8, and 15 and/or bendamustine on Day 1 and 2. Intratumoral natural killer (NK) cells/macrophages were evaluated by immunohistochemistry and flow cytometry.

RESULTS

In SU-DHL-4-OR-18-8 xenografted tumors, intratumoral NK cells/macrophages after obinutuzumab treatment were significantly decreased compared with parent tumors on Day 4. The endoplasmic reticulum stress sensor phospho-IRE1 was also decreased. In SU-DHL-4-OR-18-8 tumors, bendamustine treatment increased phospho-IRE1 on Day 4 and intratumor NK cells/macrophages on Day 10. Obinutuzumab combined with bendamustine significantly increased antitumor activity compared with each single agent on Day 29, with an increase in chemoattractant CCL6 expression on Day 10.

CONCLUSIONS

Coadministration of bendamustine in obinutuzumab retreatment may be effective against obinutuzumab-resistant tumors.

Promoting antibody-dependent cellular phagocytosis for effective macrophage-based cancer immunotherapy

Macrophages are essential in eliciting antibody-dependent cellular phagocytosis (ADCP) of cancer cells. However, a satisfactory anticancer efficacy of ADCP is contingent on early antibody administration, and resistance develops along with cancer progression. Here, we investigate the mechanisms underlying ADCP and demonstrate an effective combinatorial strategy to potentiate its efficacy. We identified paclitaxel as a universal adjuvant that efficiently potentiated ADCP by a variety of anticancer antibodies in multiple cancers. Rather than eliciting cytotoxicity on cancer cells, paclitaxel polarized macrophages toward a state with enhanced phagocytic ability. Paclitaxel-treated macrophages down-regulated cell surface CSF1R whose expression was negatively correlated with patient survival in multiple malignancies. The suppression of CSF1R in macrophages enhanced ADCP of cancer cells, suggesting a role of CSF1R in regulating macrophage phagocytic ability. Together, these findings define a potent strategy for using conventional anticancer drugs to stimulate macrophage phagocytosis and promote the therapeutic efficacy of clinical anticancer antibodies.

The Role of METTL3-Mediated N6-Methyladenosine (m6A) of JPH2 mRNA in Cyclophosphamide-Induced Cardiotoxicity

Cyclophosphamide (CYP)-induced cardiotoxicity is a common side effect of cancer treatment. Although it has received significant attention, the related mechanisms of CYP-induced cardiotoxicity remain largely unknown. In this study, we used cell and animal models to investigate the effect of CYP on cardiomyocytes. Our data demonstrated that CYP-induced a prolonged cardiac QT interval and electromechanical coupling time courses accompanied by JPH2 downregulation. Moreover, N6-methyladenosine (m6A) methylation sequencing and RNA sequencing suggested that CYP induced cardiotoxicity by dysregulating calcium signaling. Importantly, our results demonstrated that CYP induced an increase in the m6A level of JPH2 mRNA by upregulating methyltransferases METTL3, leading to the reduction of JPH2 expression levels, as well as increased field potential duration and action potential duration in cardiomyocytes. Our results revealed a novel mechanism for m6A methylation-dependent regulation of JPH2, which provides new strategies for the treatment and prevention of CYP-induced cardiotoxicity.

Follicular lymphoma and macrophages: impact of approved and novel therapies

The survival and proliferation of follicular lymphoma (FL) cells are strongly dependent on macrophages, because their presence is necessary for the propagation of FL cells in vitro. To this regard, as also shown for the majority of solid tumors, a high tissue content of tumor-associated macrophages (TAMs), particularly if showing a protumoral phenotype (also called M2), is strongly associated with a poor outcome among patients with FL treated with chemotherapy. The introduction of rituximab, an anti-CD20 antibody that can be used by TAMs to facilitate antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis, has challenged this paradigm. In the rituximab era, clinical studies have yielded conflicting results in FL, showing variable outcomes based on the type of regimen used. This highlighted, for the first time, that the impact of TAMs on the prognosis of patients with FL may depend on the administered treatment, emphasizing the need to better understand how currently available therapies affect macrophage function in FL. We summarize the impact of approved and novel therapies for FL, including radiation therapy, chemotherapy, anti-CD20 monoclonal antibodies, lenalidomide, and targeted agents, on the biology of TAMs and describe their effects on macrophage phagocytosis, polarization, and function. Although novel agents targeting the CD47/SIRPα axis are being developed and show promising activity in FL, a deeper understanding of macrophage biology and their complex pathways will help to develop novel and safer therapeutic strategies for patients with this type of lymphoma.

Evaluating upfront high-dose consolidation after R-CHOP for follicular lymphoma by clinical and genetic risk models

High-dose therapy and autologous stem cell transplantation (HDT/ASCT) is an effective salvage treatment for eligible patients with follicular lymphoma (FL) and early progression of disease (POD). Since the introduction of rituximab, HDT/ASCT is no longer recommended in first remission. We here explored whether consolidative HDT/ASCT improved survival in defined subgroups of previously untreated patients. We report survival analyses of 431 patients who received frontline rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) for advanced FL, and were randomized to receive consolidative HDT/ASCT. We performed targeted genotyping of 157 diagnostic biopsies, and calculated genotype-based risk scores. HDT/ASCT improved failure-free survival (FFS; hazard ratio [HR], 0.8, P = .07; as-treated: HR, 0.7, P = .04), but not overall survival (OS; HR, 1.3, P = .27; as-treated: HR, 1.4, P = .13). High-risk cohorts identified by FL International Prognostic Index (FLIPI), and the clinicogenetic risk models m7-FLIPI and POD within 24 months-prognostic index (POD24-PI) comprised 27%, 18%, and 22% of patients. HDT/ASCT did not significantly prolong FFS in high-risk patients as defined by FLIPI (HR, 0.9; P = .56), m7-FLIPI (HR, 0.9; P = .91), and POD24-PI (HR, 0.8; P = .60). Similarly, OS was not significantly improved. Finally, we used a machine-learning approach to predict benefit from HDT/ASCT by genotypes. Patients predicted to benefit from HDT/ASCT had longer FFS with HDT/ASCT (HR, 0.4; P = .03), but OS did not reach statistical significance. Thus, consolidative HDT/ASCT after frontline R-CHOP did not improve OS in unselected FL patients and subgroups selected by genotype-based risk models.

CD4+ T-cell killing of multiple myeloma cells is mediated by resident bone marrow macrophages

CD4+ T cells may induce potent antitumor immune responses through interaction with antigen-presenting cells within the tumor microenvironment. Using a murine model of multiple myeloma, we demonstrated that adoptive transfer of idiotype-specific CD4+ T cells may elicit curative responses against established multifocal myeloma in bone marrow. This finding indicates that the myeloma bone marrow niche contains antigen-presenting cells that may be rendered tumoricidal. Given the complexity of the bone marrow microenvironment, the mechanistic basis of such immunotherapeutic responses is not known. Through a functional characterization of antitumor CD4+ T-cell responses within the bone marrow microenvironment, we found that killing of myeloma cells is orchestrated by a population of bone marrow-resident CD11b+F4/80+MHC-IIHigh macrophages that have taken up and present secreted myeloma protein. The present results demonstrate the potential of resident macrophages as powerful mediators of tumor killing within the bone marrow and provide a basis for novel therapeutic strategies against multiple myeloma and other malignancies that affect the bone marrow.

Protection by ginseng saponins against cyclophosphamide-induced liver injuries in rats by induction of cytochrome P450 expression and mediation of the l-arginine/nitric oxide pathway based on metabolomics

Ginseng saponins (GS) are the main active compounds in Panax ginseng and have been proven to be highly effective in attenuating the side effects of chemotherapy. However, there have been no reports on the mechanism of action of GS. Treatment with GS has certain benefits, including decreasing the toxicity levels in the liver [alanine aminotransferase (ALT), albumin (ALB), alkaline phosphatase (ALP), aspartate transaminase (AST)], reducing oxidative stress [malondialdehyde (MDA), nitric oxide (NO)], diminishing inflammatory factors [interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels], and augmenting the levels of glutathione (GSH) and superoxide dismutase (SOD). The pharmacokinetics study showed that the area under the curve from 0 to 24 hr (AUC 0-24 hr) of 4-ketocyclophosphamide (4-KetoCTX) and carboxyphosphamide (CPM) was significantly increased after GS treatment. This study found that GS treatment can reduce chloroacetaldehyde (CAA) production by affecting CYP3A4, CYP2B6, and CYP2C9 protein expression in the liver. For the metabolomics study, GS attenuated the abnormalities of amino acid metabolic pathways in CP-induced liver injuries of rats and significantly enhanced the l-arginine level while reducing the serum nitric oxide (NO) level. This outcome was confirmed by the inhibition of the activities of NO synthase in the liver of rats.

Embryonic Origin and Subclonal Evolution of Tumor-Associated Macrophages Imply Preventive Care for Cancer

Macrophages are widely distributed in tissues and function in homeostasis. During cancer development, tumor-associated macrophages (TAMs) dominatingly support disease progression and resistance to therapy by promoting tumor proliferation, angiogenesis, metastasis, and immunosuppression, thereby making TAMs a target for tumor immunotherapy. Here, we started with evidence that TAMs are highly plastic and heterogeneous in phenotype and function in response to microenvironmental cues. We pointed out that efforts to tear off the heterogeneous "camouflage" in TAMs conduce to target de facto protumoral TAMs efficiently. In particular, several fate-mapping models suggest that most tissue-resident macrophages (TRMs) are generated from embryonic progenitors, and new paradigms uncover the ontogeny of TAMs. First, TAMs from embryonic modeling of TRMs and circulating monocytes have distinct transcriptional profiling and function, suggesting that the ontogeny of TAMs is responsible for the functional heterogeneity of TAMs, in addition to microenvironmental cues. Second, metabolic remodeling helps determine the mechanism of phenotypic and functional characteristics in TAMs, including metabolic bias from macrophages' ontogeny in macrophages' functional plasticity under physiological and pathological conditions. Both models aim at dissecting the ontogeny-related metabolic regulation in the phenotypic and functional heterogeneity in TAMs. We argue that gleaning from the single-cell transcriptomics on subclonal TAMs' origins may help understand the classification of TAMs' population in subclonal evolution and their distinct roles in tumor development. We envision that TAM-subclone-specific metabolic reprogramming may round-up with future cancer therapies.

Macrophage-Mediated Antibody Dependent Effector Function in Aggressive B-Cell Lymphoma Treatment is Enhanced by Ibrutinib via Inhibition of JAK2

Targeted inhibition of Bruton's Tyrosine Kinase (BTK) with ibrutinib and other agents has become important treatment options in chronic lymphocytic leukemia, Waldenström's Macroglobulinemia, Mantle cell lymphoma, and non-GCB DLBCL. Clinical trials combining small molecule inhibitors with monoclonal antibodies have been initiated at rapid pace, with the biological understanding between their synergistic interactions lagging behind. Here, we have evaluated the synergy between BTK inhibitors and monoclonal antibody therapy via macrophage mediated antibody dependent cellular phagocytosis (ADCP). Initially, we observed increased ADCP with ibrutinib, whilst second generation BTK inhibitors failed to synergistically interact with monoclonal antibody treatment. Kinase activity profiling under BTK inhibition identified significant loss of Janus Kinase 2 (JAK2) only under ibrutinib treatment. We validated this potential off-target effect via JAK inhibition in vitro as well as with CRISPR/Cas9 JAK2^-/- experiments in vivo, showing increased ADCP and prolonged survival, respectively. This data supports inhibition of the JAK-STAT (Signal Transducers and Activators of Transcription) signaling pathway in B-cell malignancies in combination with monoclonal antibody therapy to increase macrophage-mediated immune responses.

RPL41 sensitizes retinoblastoma cells to chemotherapeutic drugs via ATF4 degradation

Retinoblastoma is the most common intraocular cancer with metastatic potential affecting infants and children. Although chemotherapy is available for retinoblastoma, side effects and drug resistance are frequent. Rpl41, encoding ribosomal protein L41 (RPL41), has been identified as a tumor suppressor gene, and its targeted degradation of activating transcription factor 4 (ATF4) produces an antitumor effect. The goal of the present study is to provide experimental evidence for the clinical application of a small peptide regimen in combination with chemotherapy for the treatment of retinoblastoma and to investigate the mechanism of their combined cytotoxicity. It was observed that treatment with the RPL41 peptide alone decreased the viability, migration, and invasion of retinoblastoma Y79 and Weri-Rb1 cells, in addition to promoting cell apoptosis and cell cycle arrest. Furthermore, RPL41 protein levels showed a significantly decreased trend in retinoblastoma specimens, whereas ATF4 protein levels tended to be increased. Mechanistically, ATF4 degradation as a result of RPL41 peptide treatment was observed in retinoblastoma Y79 and Weri-Rb1 cells. Most important, low-dose administration of the RPL41 peptide significantly enhanced the antitumor effect of carboplatin, and further analysis confirmed their synergistic effect as anti-retinoblastoma therapy, indicating that RPL41 sensitized Y79 and Weri-Rb1 retinoblastoma cells to carboplatin. Thus, our data provide a preclinical rationale for the exploration of the RPL41 peptide as a potential adjuvant to carboplatin treatment in retinoblastoma.

Beyond DNA Damage: Exploring the Immunomodulatory Effects of Cyclophosphamide in Multiple Myeloma

The alkylating agent cyclophosphamide has been used in the treatment of multiple myeloma for over 60 years. At low doses, cyclophosphamide also has significant immunomodulatory activity, which can be used to modify the immunosuppressive tumor microenvironment in order to augment responses to existing therapies. Immune-mediated therapies are becoming more widespread in modern approaches to myeloma treatment. In this review, we discuss the effects cyclophosphamide has on the immune system, and how it can be used synergistically with other treatment modalities including the immunomodulatory agents, monoclonal antibodies and cellular therapies.

Drug Resistance in Non-Hodgkin Lymphomas

Non-Hodgkin lymphomas (NHL) are lymphoid tumors that arise by a complex process of malignant transformation of mature lymphocytes during various stages of differentiation. The WHO classification of NHL recognizes more than 90 nosological units with peculiar pathophysiology and prognosis. Since the end of the 20^th century, our increasing knowledge of the molecular biology of lymphoma subtypes led to the identification of novel druggable targets and subsequent testing and clinical approval of novel anti-lymphoma agents, which translated into significant improvement of patients’ outcome. Despite immense progress, our effort to control or even eradicate malignant lymphoma clones has been frequently hampered by the development of drug resistance with ensuing unmet medical need to cope with relapsed or treatment-refractory disease. A better understanding of the molecular mechanisms that underlie inherent or acquired drug resistance might lead to the design of more effective front-line treatment algorithms based on reliable predictive markers or personalized salvage therapy, tailored to overcome resistant clones, by targeting weak spots of lymphoma cells resistant to previous line(s) of therapy. This review focuses on the history and recent advances in our understanding of molecular mechanisms of resistance to genotoxic and targeted agents used in clinical practice for the therapy of NHL.

Biology and therapeutic targeting of tumour-associated macrophages

Macrophages sustain tumour progression by facilitating angiogenesis, promoting immunosuppression, and enhancing cancer cell invasion and metastasis. They also modulate tumour response to anti-cancer therapy in pre-clinical models. This knowledge has motivated the development of agents that target tumour-associated macrophages (TAMs), some of which have been investigated in early clinical trials. Here, we provide a comprehensive overview of the biology and therapeutic targeting of TAMs, highlighting opportunities, setbacks, and new challenges that have emerged after a decade of intense translational and clinical research into these multifaceted immune cells. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cyclophosphamide Enhances Cancer Antibody Immunotherapy in the Resistant Bone Marrow Niche by Modulating Macrophage FcγR Expression

Therapy-resistant microenvironments represent a major barrier toward effective elimination of disseminated cancer. Many hematologic and solid tumors are resistant to therapeutic antibodies in the bone marrow (BM), but not in the periphery (e.g., spleen). We previously showed that cyclophosphamide (CTX) sensitizes the BM niche to antibody therapeutics. Here, we show that (i) BM resistance was induced not only by the tumor but also by the intrinsic BM microenvironment; (ii) CTX treatment overcame both intrinsic and extrinsic resistance mechanisms by augmenting macrophage activation and phagocytosis, including significant upregulation of activating Fcγ receptors (FcγRIII and FcγRIV) and downregulation of the inhibitory receptor, FcγRIIB; and (iii) CTX synergized with cetuximab (anti-EGFR) and trastuzumab (anti-Her2) in eliminating metastatic breast cancer in the BM of humanized mice. These findings provide insights into the mechanisms by which CTX synergizes with antibody therapeutics in resistant niche-specific organs and its applicability in treating BM-resident tumors.

Tumor Metabolism as a Regulator of Tumor-Host Interactions in the B-Cell Lymphoma Microenvironment-Fueling Progression and Novel Brakes for Therapy

Tumor metabolism and its specific alterations have become an integral part of understanding functional alterations leading to malignant transformation and maintaining cancer progression. Here, we review the metabolic changes in B-cell neoplasia, focusing on the effects of tumor metabolism on the tumor microenvironment (TME). Particularly, innate and adaptive immune responses are regulated by metabolites in the TME such as lactate. With steadily increasing therapeutic options implicating or utilizing the TME, it has become essential to address the metabolic alterations in B-cell malignancy for therapeutic approaches. In this review, we discuss metabolic alterations of B-cell lymphoma, consequences for currently used therapy regimens, and novel approaches specifically targeting metabolism in the TME.

Lymphoma Chemotherapy: Hungry Macrophages Strike the Final Blow

Macrophages modulate tumor response to chemotherapy; in this issue, Lossos and colleagues show that high-dose alkylating agents instigate a synthetic lethal program in lymphoma cells that is independent of DNA damage and involves recruitment and priming of macrophages for antibody-mediated tumor phagocytosis. These findings implicate chemotherapy-elicited macrophages as critical effectors of lymphoma clearance during biological therapy.See related article by Lossos et al., p. 944.