Interleukin-6 mediates resistance to PI3K-pathway-targeted therapy in lymphoma

PI3Kδ activation, IL-6 overexpression, and CD37 loss cause resistance to naratuximab emtansine in lymphomas

ABSTRACT

CD37-directed antibody and cellular-based approaches have shown preclinical and promising early clinical activity. Naratuximab emtansine (Debio 1562; IMGN529) is an antibody-drug conjugate (ADC) incorporating an anti-CD37 monoclonal antibody conjugated to the maytansinoid DM1 as payload, with activity as a single agent and in combination with rituximab in patients with lymphoma. We studied naratuximab emtansine and its free payload in 54 lymphoma models, correlated its activity with CD37 expression, characterized two resistance mechanisms, and identified combination partners providing synergy. The activity, primarily cytotoxic, was more potent in B- than T-cell lymphoma cell lines. After prolonged exposure to the ADC, one diffuse large B-cell lymphoma (DLBCL) cell line developed resistance to the ADC due to the CD37 gene biallelic loss. After CD37 loss, we also observed upregulation of interleukin-6 (IL-6) and related transcripts. Recombinant IL-6 led to resistance. Anti-IL-6 antibody tocilizumab improved the ADC's cytotoxic activity in CD37+ cells. In a second model, resistance was sustained by a PIK3CD activating mutation, with increased sensitivity to PI3Kδ inhibition and a functional dependence switch from MCL1 to BCL2. Adding idelalisib or venetoclax overcame resistance in the resistant derivative and improved cytotoxic activity in the parental cells. In conclusion, targeting B-cell lymphoma with the naratuximab emtansine showed vigorous antitumor activity as a single agent, which was also observed in models bearing genetic lesions associated with inferior outcomes, such as Myc Proto-Oncogene (MYC) translocations and TP53 inactivation or R-CHOP (rituximab, cyclophosphamide, doxorubicin, Oncovin [vincristine], and prednisone) resistance. Resistant DLBCL models identified active combinations of naratuximab emtansine with drugs targeting IL-6, PI3Kδ, and BCL2.

Intra- and inter-patient diversity in hepatocellular carcinoma based on phosphorylation profiles-A pilot study in a single institution

BACKGROUND

Recent studies have addressed the efficacy of targeted drugs against hepatocellular carcinoma. However, most tumors escape a single kinase inhibition; co-inhibition of additional signaling pathways re-sensitizes resistant cancer cells to targeted drugs, thus reinforcing the importance of combination therapy for drug-resistant tumors. This study aimed to clarify the phosphorylation profiles of representative cancer-related tyrosine kinases in hepatocellular carcinoma to focus on potential therapeutic targets and to investigate the possibility of expanding combination therapy options using targeted drugs.

MATERIALS AND METHODS

Patients' whole blood, hepatocellular carcinoma tissue, and adjacent hepatic tissues were obtained during surgeries from 10 patients. All patients showed negative results for hepatitis B and hepatitis C RNA and none had a history of heavy drinking. The activation of receptor tyrosine kinases (RTKs) was analyzed by using a human RTK phosphorylation antibody array.

RESULTS

Among 62 different phospho-RTKs, 26 were activated in tumor tissues, of which ACK1, Dtk, Fyn, and Lyn were positive in 9 out of 10 cases. The median concordance rates of activated tumor and serum RTKs in each patient was 50 %. There was an inter- and intra-patient diversity of phosphorylation profiles in the serum, tumor of resected specimens, and non-tumor tissue of resected specimens in the same patients.

CONCLUSION

There was an intra- and inter- patient diversity in the activation of important and representative cancer-related RTKs. Expanding on this approach will allow us to learn how to predict the best combination of targets for each patient and to prioritize those combinations for clinical testing.

What have we learnt from the inhibition of IL-6 in RA and what are the clinical opportunities for patient outcomes?

Rheumatoid arthritis (RA) is an autoimmune disease characterised by persistent inflammation of the synovial joints as well as other tissues and organs. Left untreated, it can lead to joint damage, disability and even increased mortality. The disease is driven by inflammatory cytokines that contribute to the chronic inflammation seen in RA. Interleukin-6 (IL-6) is a key pathological cytokine and a target for treatments aiming to alleviate local and systemic inflammation. Despite advances in understanding RA and the introduction of new treatments, achieving sustained remission remains challenging. This review explores the role of IL-6 in RA pathogenesis, its potential as a treatment target and the significance of personalised medicine in RA management. IL-6 has a dual signalling mechanism, classical and trans-signalling, which influences various intracellular pathways. While several targeted therapies have emerged, no single mechanism-based therapy is universally effective due to the diversity and complexity of the disease. Different approaches to targeting IL-6 have been tested, including biologic blockade of receptors or ligands, and inhibition of IL-6 signalling. IL-6 receptor inhibitors have been validated as RA therapeutics, either alone or in combination with other treatments. Tocilizumab, the first approved IL-6 inhibitor, blocks both soluble and membrane-bound IL-6 receptors, reducing the inflammatory cascade. Clinical trials confirm the efficacy and safety of tocilizumab and its role as a treatment option for patients unresponsive to conventional therapies. The benefits of IL-6 inhibition extend beyond reduced joint inflammation to the amelioration of comorbidities like anaemia, cardiovascular disease, depression and osteoporosis. Tailoring treatment to patients' profiles and comorbidities is essential for optimal outcomes. A 'treat-to-profile' approach, focusing on a holistic view of the patient, could improve personalised medicine strategies. Biosimilars - lower-cost alternatives to biologics - further enhance the accessibility and cost-effectiveness of treatment. IL-6 inhibitors present a valuable treatment option for RA management, particularly for patients with specific comorbidities.

Deciphering JAK/STAT signaling pathway: A multifaceted approach to tumorigenesis, progression and therapeutic interventions

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, essential for cellular communication, orchestrates a myriad of physiological and pathological processes. Recently, the intricate association between the pathway's dysregulation and the progression of malignant tumors has garnered increasing attention. Nevertheless, there is no systematic summary detailing the anticancer effects of molecules targeting the JAK/STAT pathway in the context of tumor progression. This review offers a comprehensive overview of pharmaceutical agents targeting the JAK/STAT pathway, encompassing phytochemicals, synthetic drugs, and biomolecules. These agents can manifest their anticancer effects through various mechanisms, including inhibiting proliferation, inducing apoptosis, suppressing tumor metastasis, and angiogenesis. Notably, we emphasize the clinical challenges of drug resistance while spotlighting the potential of integrating JAK/STAT inhibitors with other therapies as a transformative approach in cancer treatment. Moreover, this review delves into the avant-garde strategy of employing nanocarriers to enhance the solubility and bioavailability of anticancer drugs, significantly amplifying their therapeutic prowess. Through this academic exploration of the multifaceted roles of the JAK/STAT pathway in the cancer milieu, we aim to sketch a visionary trajectory for future oncological interventions.

ERBB4-Mediated Signaling Is a Mediator of Resistance to PI3K and BTK Inhibitors in B-cell Lymphoid Neoplasms

BTK and PI3K inhibitors are among the drugs approved for the treatment of patients with lymphoid neoplasms. Although active, their ability to lead to long-lasting complete remission is rather limited, especially in the lymphoma setting. This indicates that tumor cells often develop resistance to the drugs. We started from a marginal zone lymphoma cell line, Karpas-1718, kept under prolonged exposure to the PI3Kδ inhibitor idelalisib until acquisition of resistance, or with no drug. Cells underwent transcriptome, miRNA and methylation profiling, whole-exome sequencing, and pharmacologic screening, which led to the identification of the overexpression of ERBB4 and its ligands HBEGF and NRG2 in the resistant cells. Cellular and genetic experiments demonstrated the involvement of this axis in blocking the antitumor activity of various BTK/PI3K inhibitors, currently used in the clinical setting. Addition of recombinant HBEGF induced resistance to BTK/PI3K inhibitors in parental cells and in additional lymphoma models. Combination with the ERBB inhibitor lapatinib was beneficial in resistant cells and in other lymphoma models already expressing the identified resistance factors. An epigenetic reprogramming sustained the expression of the resistance-related factors, and pretreatment with demethylating agents or EZH2 inhibitors overcame the resistance. Resistance factors were also shown to be expressed in clinical specimens. In conclusion, we showed that the overexpression of ERBB4 and its ligands represents a novel mechanism of resistance for lymphoma cells to bypass the antitumor activity of BTK and PI3K inhibitors and that targeted pharmacologic interventions can restore sensitivity to the small molecules.

Emerging Therapeutic Targets and Drug Resistance Mechanisms in Immunotherapy of Hematological Malignancies

CAR-T cell therapy has revolutionized the treatment of hematological malignancies with high remission rates in the case of ALL and NHL. This therapy has some limitations such as long manufacturing periods, persistent restricted cell sources and high costs. Moreover, combination regimens increase the risk of immune-related adverse events, so the identification new therapeutic targets is important to minimize the risk of toxicities and to guide more effective approaches. Cancer cells employ several mechanisms to evade immunosurveillance, which causes resistance to immunotherapy; therefore, a very important therapeutic approach is to focus on the development of rational combinations of targeted therapies with non-overlapping toxicities. Recent progress in the development of new inhibitory clusters of differentiation (CDs), signaling pathway molecules, checkpoint inhibitors, and immunosuppressive cell subsets and factors in the tumor microenvironment (TME) has significantly improved anticancer responses. Novel strategies regarding combination immunotherapies with CAR-T cells are the most promising approach to cure cancer.

PI3Kδ activation, IL6 over-expression, and CD37 loss cause resistance to the targeting of CD37-positive lymphomas with the antibody-drug conjugate naratuximab emtansine

Purpose

The transmembrane protein CD37 is expressed almost exclusively in lymphoid tissues, with the highest abundance in mature B cells. CD37-directed antibody- and, more recently, cellular-based approaches have shown preclinical and promising early clinical activity. Naratuximab emtansine (Debio 1562, IMGN529) is an antibodydrug conjugate (ADC) that incorporates an anti-CD37 monoclonal antibody conjugated to the maytansinoid DM1 as payload. Naratuximab emtansine has shown activity as a single agent and in combination with the anti-CD20 monoclonal antibody rituximab in B cell lymphoma patients.

Experimental Design

We assessed the activity of naratuximab emtansine using in vitro models of lymphomas, correlated its activity with CD37 expression levels, characterized two resistance mechanisms to the ADC, and identified combination partners providing synergy.

Results

The anti-tumor activity of naratuximab emtansine was tested in 54 lymphoma cell lines alongside its free payload. The median IC 50 of naratuximab emtansine was 780 pM, and the activity, primarily cytotoxic, was more potent in B than in T cell lymphoma cell lines. In the subgroup of cell lines derived from B cell lymphoma, there was some correlation between sensitivity to DM1 and sensitivity to naratuximab emtansine (r=0.28, P = 0.06). After prolonged exposure to the ADC, one diffuse large B cell lymphoma (DLBCL) cell line developed resistance to the ADC due to the biallelic loss of the CD37 gene. After CD37 loss, we also observed upregulation of IL6 (IL-6) and other transcripts from MYD88/IL6-signaling. Recombinant IL6 led to resistance to naratuximab emtansine, while the anti-IL6 antibody tocilizumab improved the cytotoxic activity of the ADC in CD37-positive cells. In a second model, resistance was sustained by an activating mutation in the PIK3CD gene, associated with increased sensitivity to PI3K δ inhibition and a switch from functional dependence on the anti-apoptotic protein MCL1 to reliance on BCL2. The addition of idelalisib or venetoclax to naratuximab emtansine overcame resistance to the ADC in the resistant derivative while also improving the cytotoxic activity of the ADC in the parental cells.

Conclusions

Targeting B cell lymphoma with the CD37 targeting ADC naratuximab emtansine showed vigorous anti-tumor activity as a single agent, which was also observed in models bearing genetic lesions associated with inferior outcomes, such as MYC translocations and TP53 inactivation or resistance to R-CHOP. Resistance DLBCL models identified active combinations of naratuximab emtansine with drugs targeting IL6, PI3K δ , and BCL2. Despite notable progress in recent decades, we still face challenges in achieving a cure for a substantial number of lymphoma patients (1,2). A pertinent example is diffuse large B cell lymphoma (DLBCL), the most prevalent type of lymphoma (3). More than half of DLBCL patients can achieve remission, but around 40% of them experience refractory disease or relapse following an initial positive response (3). Regrettably, the prognosis for many of these cases remains unsatisfactory despite introducing the most recent antibody-based or cellular therapies (3,4), underscoring the importance of innovating new therapeutic strategies and gaining insights into the mechanisms of therapy resistance. CD37 is a transmembrane glycoprotein belonging to the tetraspanin family, primarily expressed on the surface of immune cells, principally in mature B cells but also, at lower levels, in T cells, macrophages/monocytes, granulocytes and dendritic cells (5) (6-8). CD37 plays a crucial role in various immune functions, including B cell activation, proliferation, and signaling, although its precise role still needs to be fully elucidated. CD37 interacts with multiple molecules, including SYK, LYN, CD19, CD22, PI3K δ , PI3K γ , and different integrins, among others (6-8). In mice, the lack of CD37 is paired with reduced T cell-dependent antibody-secreting cells and memory B cells, apparently due to the loss of CD37-mediated clustering of α 4 β 1 integrins (VLA-4) on germinal center B cells and decreased downstream activation of PI3K/AKT signaling and cell survival (5). Reflecting the expression pattern observed in normal lymphocytes, CD37 exhibits elevated expression in all mature B-cell lymphoid neoplasms, including most lymphoma subtypes, and absence in early progenitor cells or terminally differentiated plasma cells (6,8-14). In DLBCL, CD37 expression has been reported between 40% and 90% of cases across multiple studies performed using different antibodies (10,14-16). CD37-directed antibody- and, more recently, cellular-based approaches have shown preclinical (7,10-14,17-23) and early promising clinical activity (24-32). Among the CD37-targeting agents, naratuximab emtansine (Debio 1562, IMGN529) is an antibody-drug conjugate (ADC) that incorporates the anti-CD37 humanized IgG1 monoclonal antibody K7153A conjugated to the maytansinoid DM1, as payload, via the thioether linker, N-succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC) (10). Based on the initial in vitro and in vivo evidence of anti-tumor activity in lymphoma and chronic lymphocytic leukemia (CLL) (7,10), naratuximab emtansine entered the clinical evaluation as a single agent. The phase 1 study exploring naratuximab emtansine enrolled 39 patients with relapsed/refractory B cell lymphoma (27). The overall response rate (ORR) was 13% across all patients and 22% in DLBCL patients, including the only observed complete remission (CR) (27). In preliminary results of a phase 2 trial exploring the combination of naratuximab emtansine with the anti-CD20 monoclonal antibody rituximab (18), based on positive preclinical data (18), the ORR was 45% in 76 patients with DLBCL with 24 CRs (32%), 57% in 14 patients with follicular lymphoma (five CR), 50% in four MCL patients (2 CR) (31). Here, we studied the pattern of activity of naratuximab emtansine across a large panel of cell lines derived from DLBCL and other lymphoma subtypes and characterized two resistance mechanisms to the ADC.

ERBB4-mediated signaling is a mediator of resistance to BTK and PI3K inhibitors in B cell lymphoid neoplasms

BTK and PI3K inhibitors are among the drugs approved for the treatment of patients with lymphoid neoplasms. Although active, their ability to lead as single agents to long-lasting complete remission is rather limited especially in the lymphoma setting. This indicates that tumor cells often develop resistance to the drugs. Here, we show that the overexpression of ERBB4 and its ligands represents a modality for B cell neoplastic cells to bypass the anti-tumor activity of BTK and PI3K inhibitors and that targeted pharmacological interventions can restore sensitivity to the small molecules. We started from a marginal zone lymphoma (MZL) cell line, Karpas-1718, kept under prolonged exposure to the PI3Kδ inhibitor idelalisib until acquisition of resistance, or with no drug. Cells underwent transcriptome, miRNA and methylation profiling, whole exome sequencing, and pharmacological screening which led to the identification of the overexpression of ERBB4 and its ligands HBEGF and NRG2 in the resistant cells. Cellular and genetic experiments demonstrated the involvement of this axis in blocking the anti-tumor activity of various BTK and PI3K inhibitors, currently used in the clinical setting. Addition of recombinant HBEGF induced resistance to BTK and PI3K inhibitors in parental cells but also in additional lymphoma models. Combination with the ERBB inhibitor lapatinib was beneficial in resistant cells and in other lymphoma models already expressing the identified resistance factors. Multi-omics analysis underlined that an epigenetic reprogramming affected the expression of the resistance-related factors, and pretreatment with demethylating agents or EZH2 inhibitors overcame the resistance. Resistance factors were shown to be expressed in clinical samples, further extending the findings of the study. In conclusions, we identified a novel ERBB4-driven mechanism of resistance to BTK and PI3K inhibitors and treatments that appear to overcome it.

Key points

A mechanism of secondary resistance to the PI3Kδ and BTK inhibitors in B cell neoplasms driven by secreted factors.Resistance can be reverted by targeting ERBB signaling.

Genomic landscape of mature B-cell non-Hodgkin lymphomas - an appraisal from lymphomagenesis to drug resistance

BACKGROUND

Mature B-cell non-Hodgkin lymphomas are one of the most common hematological malignancies with a divergent clinical presentation, phenotype, and course of disease regulated by underlying genetic mechanism.

MAIN BODY

Genetic and molecular alterations are not only critical for lymphomagenesis but also largely responsible for differing therapeutic response in these neoplasms. In recent years, advanced molecular tools have provided a deeper understanding regarding these oncogenic drives for predicting progression as well as refractory behavior in these diseases. The prognostic models based on gene expression profiling have also been proved effective in various clinical scenarios. However, considerable overlap does exist between the genotypes of individual lymphomas and at the same time where additional molecular lesions may be associated with each entity apart from the key genetic event. Therefore, genomics is one of the cornerstones in the multimodality approach essential for classification and risk stratification of B-cell non-Hodgkin lymphomas.

CONCLUSION

We hereby in this review discuss the wide range of genetic aberrancies associated with tumorigenesis, immune escape, and chemoresistance in major B-cell non-Hodgkin lymphomas.

Obesity and Risk for Lymphoma: Possible Role of Leptin

Obesity, which is considered a pandemic due to its high prevalence, is a risk factor for many types of cancers, including lymphoma, through a variety of mechanisms by promoting an inflammatory state. Specifically, over the last few decades, obesity has been suggested not only to increase the risk of lymphoma but also to be associated with poor clinical outcomes and worse responses to different treatments for those diseases. Within the extensive range of proinflammatory mediators that adipose tissue releases, leptin has been demonstrated to be a key adipokine due to its pleotropic effects in many physiological systems and diseases. In this sense, different studies have analyzed leptin levels and leptin/leptin receptor expressions as a probable bridge between obesity and lymphomas. Since both obesity and lymphomas are prevalent pathophysiological conditions worldwide and their incidences have increased over the last few years, here we review the possible role of leptin as a promising proinflammatory mediator promoting lymphomas.

Functional Testing to Characterize and Stratify PI3K Inhibitor Responses in Chronic Lymphocytic Leukemia

PURPOSE

PI3K inhibitors (PI3Ki) are approved for relapsed chronic lymphocytic leukemia (CLL). Although patients may show an initial response to these therapies, development of treatment intolerance or resistance remain clinical challenges. To overcome these, prediction of individual treatment responses based on actionable biomarkers is needed. Here, we characterized the activity and cellular effects of 10 PI3Ki and investigated whether functional analyses can identify treatment vulnerabilities in PI3Ki-refractory/intolerant CLL and stratify responders to PI3Ki.

EXPERIMENTAL DESIGN

Peripheral blood mononuclear cell samples (n = 51 in total) from treatment-naïve and PI3Ki-treated patients with CLL were studied. Cells were profiled against 10 PI3Ki and the Bcl-2 antagonist venetoclax. Cell signaling and immune phenotypes were analyzed by flow cytometry. Cell viability was monitored by detection of cleaved caspase-3 and the CellTiter-Glo assay.

RESULTS

pan-PI3Kis were most effective at inhibiting PI3K signaling and cell viability, and showed activity in CLL cells from both treatment-naïve and idelalisib-refractory/intolerant patients. CLL cells from idelalisib-refractory/intolerant patients showed overall reduced protein phosphorylation levels. The pan-PI3Ki copanlisib, but not the p110δ inhibitor idelalisib, inhibited PI3K signaling in CD4+ and CD8+ T cells in addition to CD19+ B cells, but did not significantly affect T-cell numbers. Combination treatment with a PI3Ki and venetoclax resulted in synergistic induction of apoptosis. Analysis of drug sensitivities to 73 drug combinations and profiling of 31 proteins stratified responders to idelalisib and umbralisib, respectively.

CONCLUSIONS

Our findings suggest novel treatment vulnerabilities in idelalisib-refractory/intolerant CLL, and indicate that ex vivo functional profiling may stratify PI3Ki responders.

Targeted and cellular therapies in lymphoma: Mechanisms of escape and innovative strategies

The therapeutic landscape for lymphomas is quite diverse and includes active surveillance, chemotherapy, immunotherapy, radiation therapy, and even stem cell transplant. Advances in the field have led to the development of targeted therapies, agents that specifically act against a specific component within the critical molecular pathway involved in tumorigenesis. There are currently numerous targeted therapies that are currently Food and Drug Administration (FDA) approved to treat certain lymphoproliferative disorders. Of many, some of the targeted agents include rituximab, brentuximab vedotin, polatuzumab vedotin, nivolumab, pembrolizumab, mogamulizumab, vemurafenib, crizotinib, ibrutinib, cerdulatinib, idelalisib, copanlisib, venetoclax, tazemetostat, and chimeric antigen receptor (CAR) T-cells. Although these agents have shown strong efficacy in treating lymphoproliferative disorders, the complex biology of the tumors have allowed for the malignant cells to develop various mechanisms of resistance to the targeted therapies. Some of the mechanisms of resistance include downregulation of the target, antigen escape, increased PD-L1 expression and T-cell exhaustion, mutations altering the signaling pathway, and agent binding site mutations. In this manuscript, we discuss and highlight the mechanism of action of the above listed agents as well as the different mechanisms of resistance to these agents as seen in lymphoproliferative disorders.

Role of TGM2 in T‑cell lymphoblastic lymphoma via regulation of IL‑6/JAK/STAT3 signalling

Transglutaminase 2 (TGM2) is a Ca²⁺-dependent enzyme that is closely associated with cancer progression; however, the function of TGM2 in T-cell lymphoma remains unclear. In the present study, TGM2 was identified as an upregulated gene by bioinformatics analysis of the microarray datasets GSE132550 and GSE143382 from the Gene Expression Omnibus database. The effects and mechanisms of TGM2 on T-cell lymphoma cells were evaluated using the Cell Counting Kit-8, colony formation assay, 5-ethynyl-2′-deoxyuridine (EdU) assay, flow cytometry, reverse transcription-quantitative polymerase chain reaction, western blotting and gene set enrichment analysis (GSEA). TGM2 expression was shown to be elevated in formalin-fixed paraffin-embedded skin biopsies from patients with T-cell lymphoma relative to skin tissue from healthy cases. TGM2 expression was also increased in T-cell lymphoma cell lines compared with that in CD4⁺ T cells. Transfection with TGM2 small interfering RNAs (siRNAs) decreased the number of EdU-positive cells, and the viability and colony formation of T-cell lymphoma cells. Furthermore, TGM2 siRNAs enhanced the apoptosis of T-cell lymphoma cells potentially via cleavage of caspase-3 and poly ADP-ribose polymerase. GSEA identified the IL-6/JAK/STAT3 pathway as a potential downstream signalling pathway of TGM2. Notably, the effects of TGM2 siRNAs on T-cell lymphoma cells were attenuated by IL-6 and accelerated by IL-6/JAK/STAT3 inhibitor AG490. These findings indicated that TGM2 siRNAs inhibited the proliferation of T-cell lymphoma cells by regulating the IL-6/JAK/STAT3 signalling pathway; therefore, TGM2 may function as a potential therapeutic target for T-cell lymphoma.

SAF-248, a novel PI3Kδ-selective inhibitor, potently suppresses the growth of diffuse large B-cell lymphoma

PI3Kδ is expressed predominately in leukocytes and overexpressed in B-cell-related malignances. PI3Kδ has been validated as a promising target for cancer therapy, and specific PI3Kδ inhibitors were approved for clinical practice. However, the substantial toxicity and relatively low efficacy as a monotherapy in diffuse large B-cell lymphoma (DLBCL) limit their clinical use. In this study, we described a novel PI3Kδ inhibitor SAF-248, which exhibited high selectivity for PI3Kδ (IC₅₀ = 30.6 nM) over other PI3K isoforms at both molecular and cellular levels, while sparing most of the other human protein kinases in the kinome profiling. SAF-248 exhibited superior antiproliferative activity against 27 human lymphoma and leukemia cell lines compared with the approved PI3Kδ inhibitor idelalisib. In particular, SAF-248 potently inhibited the proliferation of a panel of seven DLBCL cell lines (with GI₅₀ values < 1 μM in 5 DLBCL cell lines). We demonstrated that SAF-248 concentration-dependently blocked PI3K signaling followed by inducing G₁ phase arrest and apoptosis in DLBCL KARPAS-422, Pfeiffer and TMD8 cells. Its activity against the DLBCL cells was negatively correlated to the protein level of PI3Kα. Oral administration of SAF-248 dose-dependently inhibited the growth of xenografts derived from Pfeiffer and TMD8 cells. Activation of mTORC1, MYC and JAK/STAT signaling was observed upon prolonged treatment and co-targeting these pathways would potentiate the activity of SAF-248. Taken together, SAF-248 is a promising selective PI3Kδ inhibitor for the treatment of DLBCL and rational drug combination would further improve its efficacy.

H3.3K27M Mutation Controls Cell Growth and Resistance to Therapies in Pediatric Glioma Cell Lines

Simple Summary

Although the involvement of the H3.3K27M mutation in Diffuse Midline Glioma tumorigenesis is now established, its role in their resistance to treatments and, therefore, in their fatal outcome remains poorly documented. Here, thanks to our models of H3.3K27M induction in pediatric glioma cells, we finally shed light on this crucial issue. Hence, we demonstrate here for the first time that H3.3K27M can increase cell radioresistance capabilities independently of TP53 alterations. Moreover, thanks to a drug library screening, we evidenced that this mutation can, depending on the cellular context, drastically modulate the response of these cells to different classes of compounds, thus paving the way for new therapeutic strategies. Altogether, our results provide here the proof that, beyond its role in tumorigenesis, the presence of H3.3K27M mutation by itself alters the response to treatments of pediatric glioma cells.

Abstract

High-grade gliomas represent the most lethal class of pediatric tumors, and their resistance to both radio- and chemotherapy is associated with a poor prognosis. Recurrent mutations affecting histone genes drive the tumorigenesis of some pediatric high-grade gliomas, and H3K27M mutations are notably characteristic of a subtype of gliomas called DMG (Diffuse Midline Gliomas). This dominant negative mutation impairs H3K27 trimethylation, leading to profound epigenetic modifications of genes expression. Even though this mutation was described as a driver event in tumorigenesis, its role in tumor cell resistance to treatments has not been deciphered so far. To tackle this issue, we expressed the H3.3K27M mutated histone in three initially H3K27-unmutated pediatric glioma cell lines, Res259, SF188, and KNS42. First, we validated these new H3.3K27M-expressing models at the molecular level and showed that K27M expression is associated with pleiotropic effects on the transcriptomic signature, largely dependent on cell context. We observed that the mutation triggered an increase in cell growth in Res259 and SF188 cells, associated with higher clonogenic capacities. Interestingly, we evidenced that the mutation confers an increased resistance to ionizing radiations in Res259 and KNS42 cells. Moreover, we showed that H3.3K27M mutation impacts the sensitivity of Res259 cells to specific drugs among a library of 80 anticancerous compounds. Altogether, these data highlight that, beyond its tumorigenic role, H3.3K27M mutation is strongly involved in pediatric glioma cells’ resistance to therapies, likely through transcriptomic reprogramming.

Barriers to achieving a cure in lymphoma

Lymphoma is a diverse disease with a variety of different subtypes, each characterized by unique pathophysiology, tumor microenvironment, and underlying signaling pathways leading to oncogenesis. With our increasing understanding of the molecular biology of lymphoma, there have been a number of novel targeted therapies and immunotherapy approaches that have been developed for the treatment of this complex disease. Despite rapid progress in the field, however, many patients still relapse largely due to the development of drug resistance to these therapies. A better understanding of the mechanisms underlying resistance is needed to develop more novel treatment strategies that circumvent these mechanisms and design better treatment algorithms that personalize therapies to patients and sequence these therapies in the most optimal manner. This review focuses on the recent advances in therapies in lymphoma, including targeted therapies, monoclonal antibodies, antibody-drug conjugates, cellular therapy, bispecific antibodies, and checkpoint inhibitors. We discuss the genetic and cellular principles of drug resistance that span across all the therapies, as well as some of the unique mechanisms of resistance that are specific to these individual classes of therapies and the strategies that have been developed to address these modes of resistance.

Janus Kinase Signaling: Oncogenic Criminal of Lymphoid Cancers

Simple Summary

Janus kinases (JAKs) are transmembrane receptors that pass signals from extracellular ligands to downstream. Increasing evidence has suggested that JAK family aberrations promote lymphoid cancer pathogenesis and progression through mediating gene expression via the JAK/STAT pathway or noncanonical JAK signaling. We are here to review how canonical JAK/STAT and noncanonical JAK signalings are represented and deregulated in lymphoid malignancies and how to target JAK for therapeutic purposes.

Abstract

The Janus kinase (JAK) family are known to respond to extracellular cytokine stimuli and to phosphorylate and activate signal transducers and activators of transcription (STAT), thereby modulating gene expression profiles. Recent studies have highlighted JAK abnormality in inducing over-activation of the JAK/STAT pathway, and that the cytoplasmic JAK tyrosine kinases may also have a nuclear role. A couple of anti-JAK therapeutics have been developed, which effectively harness lymphoid cancer cells. Here we discuss mutations and fusions leading to JAK deregulations, how upstream nodes drive JAK expression, how classical JAK/STAT pathways are represented in lymphoid malignancies and the noncanonical and nuclear role of JAKs. We also summarize JAK inhibition therapeutics applied alone or synergized with other drugs in treating lymphoid malignancies.

IL-6/STAT3 signaling pathway regulates the proliferation and damage of intestinal epithelial cells in patients with ulcerative colitis via H3K27ac

The aim of the present study was to investigate the effect of the IL-6/STAT3 signaling pathway on intestinal epithelial barrier injury in patients with ulcerative colitis (UC). Fifty-two patients with UC and 21 healthy subjects were recruited. The expression level of IL-6 in plasma was determined by ELISA. Normal human colon mucosal epithelial NCM460 cells were treated with IL-6 or plasma from the patients with UC. Then, the transepithelial electrical resistance value, fluorescein yellow permeability and zonulin release were evaluated. Using reverse transcription-quantitative (q)PCR and western blotting, claudin (CLDN) 1 and CLDN2 expression levels were analyzed. Furthermore, western blotting was used to detect phosphorylation of STAT3. Chromatin immunoprecipitation-qPCR was performed to investigate the enrichment of H3K27ac in the promoter regions of CLDN1 and CLDN2. The present study revealed that IL-6 content was elevated in the plasma from patients with UC and increased with the progression of the disease. IL-6 was also observed to induce intestinal epithelial cell barrier injury and regulate barrier function by influencing the expression of tight junction-related proteins, as well as STAT3. The IL-6/STAT3 signaling pathway regulated transcription of CLDN1 and CLDN2 by affecting the enrichment of histone H3K27ac in their promoter regions. Thus, the significantly increased expression level of IL-6 in the peripheral blood of patients with UC indicates a positive association with the development of UC. Furthermore, the IL-6/STAT3 signaling pathway influences the function of the intestinal barrier by affecting the H3K27ac level in intestinal epithelial cells.

Combined Inhibition of Akt and mTOR Is Effective Against Non-Hodgkin Lymphomas

Non-Hodgkin lymphoma (NHL) are a diverse group of hematological malignancies comprised of over 60 subtypes. These subtypes range from indolent to aggressive. The PI3K/Akt/mTOR pathway has been shown to contribute to cell survival and proliferation and is constitutively active in most NHL. MK-7075 (miransertib) and MK-4440 are small molecules that effectively inhibit Akt and have entered clinical development. Using in vitro and in vivo models of NHL, we explored targeting the kinase Akt with miransertib and MK-4440 alone or in combination with the mTORC1 inhibitor, rapamycin (sirolimus). Both Akt inhibitors inhibited the pathway and NHL proliferation in a subtype-dependent manner. However, these compounds had a minimal effect on the viability of primary B-cells. Importantly, the combination of miransertib and sirolimus synergistically reduced cell proliferation in NHL, including in one indolent subtype, e.g., follicular lymphoma (FL), and two aggressive subtypes, e.g., diffuse large B-cell lymphoma (DLBCL) and primary effusion lymphoma (PEL). To establish in vivo efficacy, we used several xenograft models of FL, DLBCL, and PEL. The results obtained in vivo were consistent with the in vitro studies. The FL xenograft was highly sensitive to the inhibition of Akt alone; however, the tumor burden of PEL xenografts was only significantly reduced when both Akt and mTORC1 were targeted. These data suggest that targeting the PI3K/Akt/mTOR pathway with Akt inhibitors such as miransertib in combination with mTOR inhibitors serves as a broadly applicable therapeutic in NHL.

Revisiting IL-6 expression in the tumor microenvironment of classical Hodgkin lymphoma

Interleukin-6 (IL-6) can induce therapeutic resistance for several cancer agents currently used to treat classical Hodgkin lymphoma (cHL). We aimed to investigate whether the presence of IL-6+ leukocytes and IL-6+ Hodgkin-Reed-Sternberg (HRS) cells in the tumor microenvironment (TME) was associated with adverse survival outcomes, expression of other immune markers, and serum IL-6 levels. We used a contemporarily treated cohort (n = 136), with a median follow-up of 13.8 years (range, 0.59-15.9 years). We performed immunohistochemistry with an IL-6 antibody on tissue microarrays from diagnostic biopsies of cHL patients. Patients with IL-6+ leukocytes ≥1% (n = 54 of 136) had inferior event-free survival (hazard ratio [HR] = 3.58; 95% confidence interval [CI], 1.80-7.15) and overall survival (HR = 6.71; 95% CI, 2.51-17.99). The adverse survival was maintained in multivariate Cox regression and propensity score-matched analyses, adjusting for well-known poor-prognostic covariates. The presence of IL-6+ HRS cells and high serum IL-6 levels were not associated with survival. IL-6+ leukocytes correlated with increased proportions of IL-6+ HRS cells (P < .01), CD138+ plasma cells (P < .01), CD68+ macrophages (P = .02), and tryptase-positive mast cells (P < .01). IL-6+ HRS cells correlated with increased proportions of CD68+ macrophages (P = .03), programmed death-ligand 1-positive (PD-L1+) leukocytes (P = .04), and PD-L1+ HRS cells (P < .01). Serum-IL-6 lacked correlation with IL-6 expression in the TME. This is the first study highlighting the adverse prognostic impact of IL-6+ leukocytes in the TME in a cohort of contemporarily treated adult patients with cHL.

Arylated gold nanoparticles have no effect on the adipogenic differentiation of MG-63 cells nor regulate any key signaling pathway during the differentiation

OBJECTIVE

MG-63 cells that have osteoblastic and adipogenic differentiation potential were evaluated for internalization, and adipogenic differentiation in the presence and absence of the covalently functionalized aryl gold nanoparticles (AuNPs-C6H4-4-COOH).

RESULTS

Inductively coupled plasma, flow cytometry and confocal microscopy analyses confirmed that gold nanoparticles were easily internalized by MG-63 cells. The MG-63 cells were differentiated into adipocytes without gold-aryl nanoparticles and with the gold-aryl nanoparticles at 5 µM concentration in both induction and maintenance media. The lipid content assay and the relative expressions of PPAR-γ, ADR1, GLUT1 and GLUT4 genes showed no significant variation with and without the gold nanoparticles treatment. Differential phosphorylation levels of 43 kinases phosphorylation sites were evaluated using the human phospho-kinase array to assess the effect of the gold nanoparticles on the signaling pathways during the differentiation. No kinase phosphorylation site was differentially phosphorylated with two or more folds after the nanoparticles treatment after the first day as well as at the end of MG-63 cells differentiation. The gold-aryl nanoparticles do not affect MG-63 cells differentiation into adipocytes neither do they affect any key signaling pathway. These properties make these gold nanoparticles suitable for future drug delivery and medical applications.

Angiotensin II enhances the proliferation of Natural Killer/T-cell lymphoma cells via activating PI3K/Akt signaling pathway

The present study was to determine the roles of Angiotensin (Ang) II in the growth of lymphoma in nude mice and the proliferation and viability of the human Natural Killer/T (NK/T)-cell lymphoma cell line SNK-6, and the activation of downstream signaling pathway. Lymphoma samples and corresponding normal tissues were obtained from lymphoma patients. Proliferation of SNK-6 cells was detected by CCK8 or MTT assay. The levels of Ang II and its receptor Ang II type 1 receptor (AT1R) were higher in lymphoma tissues than those in control tissues. Ang II increased the lymphoma volume and size in nude mice, the proliferation and viability and the proliferating cell nuclear antigen (PCNA) and Ki67 levels of SNK-6 cells. Losartan, an antagonist of AT1R, reduced lymphoma volume and size in nude mice, and the proliferation and viability and the PCNA and Ki67 levels of SNK-6 cells. The levels of phosphorylated phosphatidylinositol 3-kinase (p-PI3K) and phosphorylated protein kinase B (p-Akt) were increased by Ang II and then reduced by losartan in SNK-6 cells. The proliferation and viability of SNK-6 cells were increased by Ang II, but these increases were inhibited by PI3K inhibitor wortmannin and Akt inhibitor MK2206. The increases of PCNA and Ki67 induced by Ang II were inhibited by wortmannin or MK2206 in SNK-6 cells. These results indicate that Ang II/AT1R is activated in lymphoma, and Ang II promotes the progression of lymphoma in nude mice and the proliferation and viability of SNK-6 cells via activating PI3K/Akt signaling pathway.

Update on the role of copanlisib in hematologic malignancies

Clinical research in hematologic malignancies is continually advancing with emerging concepts in therapy and evolving results from clinical protocols. Targeting of the PI3K pathway remains a valuable treatment across both hematologic and solid malignancies. There are currently four United States Food and Drug Administration (FDA)-approved PI3K inhibitors, with several others in development. Copanlisib is a pan-PI3K inhibitor currently FDA-approved for the treatment of relapsed/refractory follicular lymphoma (FL) following two lines of therapy. Since FDA approval, there have been further investigations into the long-term safety profile of copanlisib, as well as treatment of FL and other lymphoma subtypes, both indolent and aggressive. Here, we review the most recent available data from clinical trials, describe the management of the most common side effects, and explore future concepts. The use of copanlisib as part of a combination therapy for various hematologic malignancies will also be discussed. Copanlisib is a unique drug compared with other PI3K inhibitors, with remarkable potential to improve our armamentarium in cancer treatment.

NVP-BEZ235 or JAKi Treatment leads to decreased survival of examined GBM and BBC cells

Cancer cells almost universally harbor constitutively active Phosphatidylinositol-3 Kinase (PI3K) Pathway activity via mutation of key signaling components and/or epigenetic mechanisms. Scores of PI3K Pathway inhibitors are currently under investigation as putative chemotherapeutics. However, feedback and stem cell mechanisms induced by PI3K Pathway inhibition can lead to reduced treatment efficacy. To address therapeutic barriers, we examined whether JAKi would reduce stem gene expression in a setting of PI3K Pathway inhibition in order to improve treatment efficacy. We targeted the PI3K Pathway with NVP-BEZ235 (dual PI3K and mTOR inhibitor) in combination with the Janus Kinase inhibitor JAKi in glioblastoma (GBM) and basal-like breast cancer (BBC) cell lines. We examined growth, gene expression, and apoptosis in cells treated with NVP-BEZ235 and/or JAKi. Growth and recovery assays showed no significant impact of dual treatment with NVP-BEZ235/JAKi compared to NVP-BEZ235 treatment alone. Gene expression and flow cytometry revealed that single and dual treatments induced apoptosis. Stem gene expression was retained in dual NVP-BEZ235/JAKi treatment samples. Future in vivo studies may give further insight into the impact of combined NVP-BEZ235/JAKi treatment in GBM and BBC.

Overcoming resistance to targeted therapies in chronic lymphocytic leukemia

Insight into the critical role of B-cell receptor signaling for the pathogenesis of chronic lymphocytic leukemia (CLL) led to the development of targeted therapies directed at key regulators of cell survival. Agents targeting B-cell lymphoma-2 protein, Bruton's tyrosine kinase (BTK), and phosphatidylinositol 3-kinase are approved for treatment of CLL, and have significantly improved the disease management. Nevertheless, acquired resistance to the targeted therapies is a challenge still to be resolved. The mechanisms underlying resistance are becoming clearer, and include secondary mutations within the drug target and activation of bypass pathways. This knowledge has allowed development of strategies to prevent and overcome treatment resistance. Approaches to prevent resistance include targeting bypass mechanisms by combination therapies, temporally sequencing of therapies, improved clinical trial designs, and real-time monitoring of patient response. A rational design of drug sequencing may secure effective treatment options at the relapsed setting. Next-generation inhibitors and bispecific antibodies have the potential to overcome resistance to the BTK inhibitor ibrutinib. Immunotherapy, including chimeric antigen receptor-modified T-cell therapy, is explored for relapsed CLL. Here, recent advances that have contributed to the understanding of resistance to targeted therapies in CLL are discussed. Strategies for managing resistance are reviewed, including translational, real-world, and clinical perspectives.

Genetic and Non-Genetic Mechanisms of Resistance to BCR Signaling Inhibitors in B Cell Malignancies

The approval of BTK and PI3K inhibitors (ibrutinib, idelalisib) represents a revolution in the therapy of B cell malignancies such as chronic lymphocytic leukemia (CLL), mantle-cell lymphoma (MCL), diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), or Waldenström's macroglobulinemia (WM). However, these "BCR inhibitors" function by interfering with B cell pathophysiology in a more complex way than anticipated, and resistance develops through multiple mechanisms. In ibrutinib treated patients, the most commonly described resistance-mechanism is a mutation in BTK itself, which prevents the covalent binding of ibrutinib, or a mutation in PLCG2, which acts to bypass the dependency on BTK at the BCR signalosome. However, additional genetic aberrations leading to resistance are being described (such as mutations in the CARD11, CCND1, BIRC3, TRAF2, TRAF3, TNFAIP3, loss of chromosomal region 6q or 8p, a gain of Toll-like receptor (TLR)/MYD88 signaling or gain of 2p chromosomal region). Furthermore, relative resistance to BTK inhibitors can be caused by non-genetic adaptive mechanisms leading to compensatory pro-survival pathway activation. For instance, PI3K/mTOR/Akt, NFkB and MAPK activation, BCL2, MYC, and XPO1 upregulation or PTEN downregulation lead to B cell survival despite BTK inhibition. Resistance could also arise from activating microenvironmental pathways such as chemokine or integrin signaling via CXCR4 or VLA4 upregulation, respectively. Defining these compensatory pro-survival mechanisms can help to develop novel therapeutic combinations of BTK inhibitors with other inhibitors (such as BH3-mimetic venetoclax, XPO1 inhibitor selinexor, mTOR, or MEK inhibitors). The mechanisms of resistance to PI3K inhibitors remain relatively unclear, but some studies point to MAPK signaling upregulation via both genetic and non-genetic changes, which could be co-targeted therapeutically. Alternatively, drugs mimicking the BTK/PI3K inhibition effect can be used to prevent adhesion and/or malignant B cell migration (chemokine and integrin inhibitors) or to block the pro-proliferative T cell signals in the microenvironment (such as IL4/STAT signaling inhibitors). Here we review the genetic and non-genetic mechanisms of resistance and adaptation to the first generation of BTK and PI3K inhibitors (ibrutinib and idelalisib, respectively), and discuss possible combinatorial therapeutic strategies to overcome resistance or to increase clinical efficacy.

High serum levels of IL-2R, IL-6, and TNF-α are associated with higher tumor burden and poorer outcome of follicular lymphoma patients in the rituximab era

The clinical behavior of FL patients is heterogeneous. The levels of sIL-2R have been correlated with tumor burden and outcome in FL. However, the impact of IL-6 and TNF-α in this disease is unclear. We studied 253 patients diagnosed with grade 1-3a FL between 2002 and 2018, with available information on serum levels of sIL-2R, IL-6, and TNF-α at diagnosis. Patients with cytokine levels above the cutoff had features of a higher tumor burden and higher-risk disease. Levels of any of the studied cytokines above the cutoff and a higher number of cytokines above the cutoff impacted on a shorter PFS and OS. TNF-α levels were an independent predictor of a poorer PFS. No differences were observed in the risk of histological transformation or second malignancies. The determination of cytokine levels in FL patients is feasible in clinical practice, and elevated levels are associated with a higher tumor burden and poorer survival.

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.

STAT3 Activation and Oncogenesis in Lymphoma

Signal transducer and activator of transcription 3 (STAT3) is an important and the most studied transcription factor in the Janus kinase (JAK)/STAT signaling pathway. STAT3 mediates the expression of various genes that play a critical role in many cellular and biological processes, such as cell proliferation, survival, differentiation, migration, angiogenesis, and inflammation. STAT3 and associated JAKs are activated and tightly regulated by a variety of cytokines and growth factors and their receptors in normal immune responses. However, abnormal expression of STAT3 leads to its constitutive activation, which promotes malignant transformation and tumor progression through oncogenic gene expression in numerous human cancers. Human lymphoma is a heterogeneous malignancy of T and B lymphocytes. Constitutive signaling by STAT3 is an oncogenic driver in several types of B-cell lymphoma and most of T-cell lymphomas. Aberrant STAT3 activation can also induce inappropriate expression of genes involved in tumor immune evasion such as PD-L1. In this review, we focus on the oncogenic role of STAT3 in human lymphoma and highlight potential therapeutic intervention by targeting JAK/STAT3 signaling.