The kava chalcone flavokawain B exerts inhibitory activity and synergizes with BCL-2 inhibition in malignant B-cell lymphoma.

BACKGROUND: B-cell lymphoma, which originates from B cells at diverse differentiation stages, is the most common non-Hodgkin lymphoma with tremendous treatment challenges and unsatisfactory clinical outcomes. Flavokawain B (FKB), a naturally occurring chalcone extracted from kava, possesses promising anticancer properties. However, evidence on the effects of FKB on hematological malignancies, particularly lymphomas, remains scarce. PURPOSE: This study aimed to investigate the antilymphoma effect of FKB and its underlying mechanisms. STUDY DESIGN/METHODS: Proliferation assays, flow cytometry, and western blotting were employed to determine whether and how FKB affected B-cell lymphoma cell lines in vitro. Xenograft mouse models were established to evaluate the antilymphoma efficacy of FKB in vivo. RESULTS: FKB reduced the viability of a panel of B-cell lymphoma cell lines in a dose- and time-dependent manner. Mitochondrial apoptosis was markedly induced by FKB, as evidenced by an increased percentage of annexin V-positive cells, a loss of mitochondrial membrane potential, and cleavage of caspase-3 and PARP. Moreover, FKB inhibited BCL-XL expression and synergized with the BCL-2 inhibitor ABT-199. Mechanistically, FKB treatment decreased the phosphorylation of Akt, mammalian target of rapamycin (mTOR), glycogen synthase kinase-3ß (GSK3ß), and ribosomal protein S6 (RPS6). Pharmacological blockage of phosphoinositide 3-kinase (PI3K), Akt, or GSK3ß potentiated the activity of FKB, indicating the involvement of the PI3K/Akt cascade in FKB-mediated inhibitory effects. In mouse xenograft models, the intraperitoneal administration of FKB significantly decreased lymphoma growth, accompanied by diminished mitosis and Ki-67 staining of tumor tissues. CONCLUSION: Our data demonstrate the robust therapeutic potential of FKB in the treatment of B-cell lymphoma.

Bendamustine lymphodepletion is a well-tolerated alternative to fludarabine and cyclophosphamide lymphodepletion for axicabtagene ciloleucel therapy for aggressive B-cell lymphoma.

Fludarabine/cyclophosphamide (Flu/Cy) is established for lymphodepletion (LD) prior to standard-of-care CAR T-cell therapy for lymphoma. There is ongoing need to test alternative LD regimens to preserve efficacy, improve safety, and address challenges including the recent national fludarabine shortage. We retrospectively evaluated outcomes among patients with relapsed/refractory aggressive B-cell lymphoma who received bendamustine (n = 27) or Flu/Cy (n = 42) LD before axicabtagene ciloleucel (axi-cel) at our institution. The median change in absolute lymphocyte count from pre-LD to time of axi-cel infusion was -0.6×109 /L in bendamustine cohort and -0.7×109 /L in Flu/Cy cohort. The best overall response/complete response rates were 77.8% (95% CI: 57.7%-91.4%)/48.1% (95% CI: 28.7%-68.1%) among bendamustine cohort and 81.0% (95% CI: 65.9%-91.4%)/50.0% (95% CI: 34.2%-65.8%) among Flu/Cy cohort. Six-month progression-free survival were 43.8% (95% CI: 24.7%-61.3%) and 55.6% (95% CI: 39.0%-69.3%) in bendamustine and Flu/Cy cohorts, while 6-month overall survival were 81.5% (95% CI: 61.1%-91.8%) and 90.4% (95% CI: 76.4%-96.3%), respectively. Relative to Flu/Cy-treated patients, bendamustine-treated patients did not show an increase in hazards associated with experiencing progression/relapse/death (aHR:1.4 [95% CI: 0.7-2.8]; p = .32) or death (aHR:1.6 [95% CI: 0.5-5.6]; p = .46), after adjusting for baseline number of prior therapies and refractory disease. Any grade/grade ≥3 CRS were observed in 89%/3.7% and 86%/4.8% among bendamustine and Flu/Cy cohorts, while any grade ICANS/grade ≥3 ICANS were observed in 30%/19% and 55%/31% respectively. While more Flu/Cy-treated patients experienced grade ≥3 neutropenia compared with bendamustine-treated patients (100% vs. 68%), grade ≥3 infectious complications were comparable (24% vs. 19% respectively). More patients received bendamustine LD and axi-cel as outpatient than Flu/Cy cohort, without increased toxicities and with shorter median inpatient stays. In conclusion, we observed comparable efficacy and lower any grade ICANS among patients receiving bendamustine relative to Flu/Cy LD, followed by axi-cel.

Oxidative stress enhances the therapeutic action of a respiratory inhibitor in MYC-driven lymphoma.

MYC is a key oncogenic driver in multiple tumor types, but concomitantly endows cancer cells with a series of vulnerabilities that provide opportunities for targeted pharmacological intervention. For example, drugs that suppress mitochondrial respiration selectively kill MYC-overexpressing cells. Here, we unravel the mechanistic basis for this synthetic lethal interaction and exploit it to improve the anticancer effects of the respiratory complex I inhibitor IACS-010759. In a B-lymphoid cell line, ectopic MYC activity and treatment with IACS-010759 added up to induce oxidative stress, with consequent depletion of reduced glutathione and lethal disruption of redox homeostasis. This effect could be enhanced either with inhibitors of NADPH production through the pentose phosphate pathway, or with ascorbate (vitamin C), known to act as a pro-oxidant at high doses. In these conditions, ascorbate synergized with IACS-010759 to kill MYC-overexpressing cells in vitro and reinforced its therapeutic action against human B-cell lymphoma xenografts. Hence, complex I inhibition and high-dose ascorbate might improve the outcome of patients affected by high-grade lymphomas and potentially other MYC-driven cancers.

Anticancer Activity of Continentalic Acid in B-Cell Lymphoma.

Aralia continentalis has been used in Korea as a folk remedy for arthralgia, rheumatism, and inflammation. However, its anti-lymphoma effect remains uncharacterized. Here, we demonstrate that A. continentalis extract and its three diterpenes efficiently kill B-lymphoma cells. Our in vitro and in vivo results suggest that the cytotoxic activities of continentalic acid, a major diterpene from A. continentalis extract, are specific towards cancer cells while leaving normal murine cells and tissues unharmed. Mechanistically, continentalic acid represses the expression of pro-survival Bcl-2 family members, such as Mcl-1 and Bcl-xL. It dissociates the mitochondrial membrane potential, leading to the stimulation of effector caspase 3/7 activities and, ultimately, cell death. Intriguingly, this agent therapeutically synergizes with roflumilast, a pan-PDE4 inhibitor that has been successfully repurposed for the treatment of aggressive B-cell malignancies in recent clinical tests. Our findings unveiled that A. continentalis extract and three of the plant's diterpenes exhibit anti-cancer activities. We also demonstrate the synergistic inhibitory effect of continentalic acid on the survival of B-lymphoma cells when combined with roflumilast. Taken in conjunction, continentalic acid may hold significant potential for the treatment of B-cell lymphoma.

Eupafolin induces autophagy and apoptosis in B-cell non-Hodgkin lymphomas.

OBJECTIVES: Eupafolin, an extract from Artemisia princeps, possesses multiple pharmacological activities. However, the effect of eupafolin on B-cell non-Hodgkin lymphomas is currently unknown. In this study, we report that eupafolin shows anticancer activity against B-cell non-Hodgkin lymphomas cell line, OCI-LY-3. METHODS: A CCK-8 assay was used to detect the proliferation inhibition of OCI-LY-3 cells treated with additional concentrations of eupafolin. Flow cytometric analysis method of the cell apoptosis was detected after cells stained with Annexin-V-FITC/PI according to the manufacturer's instructions. The proteins in the cell were detected by western blot after treatment with eupafolin. KEY FINDINGS: Eupafolin induced apoptosis in this cell line evidenced by the caspases activation, cleavage of PARP and downregulation of Bcl-2 and Bcl-xl. Eupafolin-induced autophagy was verified by accumulation of LC3-II and beclin-1. Eupafolin induced autophagy promoting apoptosis by the treatment of eupafolin combined with autophagy inhibitors 3-methyladenine and bafilomycin A1, respectively. Moreover, we disclose that the expression levels of p-Akt, p-mTOR,p-P70S6K and p-4EBP1 decrease in the Akt/mTOR signalling pathway, and the expression levels of proteins in the NF-ΚB signalling pathway, such as p-p65, p-IκBα, is downregulation. CONCLUSIONS: Together, these results provide crucial evidences explaining the antitumour activity of eupafolin in human NHL cell line, OCI-LY-3.

Pirtobrutinib in relapsed or refractory B-cell malignancies (BRUIN): a phase 1/2 study.

BACKGROUND: Covalent Bruton's tyrosine kinase (BTK) inhibitors are efficacious in multiple B-cell malignancies, but patients discontinue these agents due to resistance and intolerance. We evaluated the safety and efficacy of pirtobrutinib (working name; formerly known as LOXO-305), a highly selective, reversible BTK inhibitor, in these patients. METHODS: Patients with previously treated B-cell malignancies were enrolled in a first-in-human, multicentre, open-label, phase 1/2 trial of the BTK inhibitor pirtobrutinib. The primary endpoint was the maximum tolerated dose (phase 1) and overall response rate (ORR; phase 2). This trial is registered with ClinicalTrials.gov, NCT03740529. FINDINGS: 323 patients were treated with pirtobrutinib across seven dose levels (25 mg, 50 mg, 100 mg, 150 mg, 200 mg, 250 mg, and 300 mg once per day) with linear dose-proportional exposures. No dose-limiting toxicities were observed and the maximum tolerated dose was not reached. The recommended phase 2 dose was 200 mg daily. Adverse events in at least 10% of 323 patients were fatigue (65 [20%]), diarrhoea (55 [17%]), and contusion (42 [13%]). The most common adverse event of grade 3 or higher was neutropenia (32 [10%]). There was no correlation between pirtobrutinib exposure and the frequency of grade 3 treatment-related adverse events. Grade 3 atrial fibrillation or flutter was not observed, and grade 3 haemorrhage was observed in one patient in the setting of mechanical trauma. Five (1%) patients discontinued treatment due to a treatment-related adverse event. In 121 efficacy evaluable patients with chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL) treated with a previous covalent BTK inhibitor (median previous lines of treatment 4), the ORR with pirtobrutinib was 62% (95% CI 53-71). The ORR was similar in CLL patients with previous covalent BTK inhibitor resistance (53 [67%] of 79), covalent BTK inhibitor intolerance (22 [52%] of 42), BTK C481-mutant (17 [71%] of 24) and BTK wild-type (43 [66%] of 65) disease. In 52 efficacy evaluable patients with mantle cell lymphoma (MCL) previously treated with covalent BTK inhibitors, the ORR was 52% (95% CI 38-66). Of 117 patients with CLL, SLL, or MCL who responded, all but eight remain progression-free to date. INTERPRETATION: Pirtobrutinib was safe and active in multiple B-cell malignancies, including patients previously treated with covalent BTK inhibitors. Pirtobrutinib might address a growing unmet need for alternative therapies for these patients. FUNDING: Loxo Oncology.

Safety and financial analysis of outpatient dose-adjusted EPOCH for B-cell lymphoma at a tertiary comprehensive cancer center.

INTRODUCTION: Dose-adjusted (DA-) EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin) is a front-line treatment option for aggressive B-cell lymphomas. Due to regimen complexity, inpatient administration of DA-EPOCH has been historically required. Moffitt Cancer Center (MCC) developed an Inpatient/Outpatient (IPOP) program to facilitate administration of complicated regimens in the outpatient setting. We hypothesized that outpatient administration of DA-EPOCH at a comprehensive cancer center is both safe and cost-effective. METHODS: We conducted a single-center, retrospective chart review including B-cell lymphoma patients who were 18 years or older and who had received DA-EPOCH at MCC from April 26, 2017 through August 10, 2019. The primary endpoint was hospital admissions during outpatient chemotherapy administration. Additional safety endpoints included hospitalizations between cycles, infectious complications, extravasations, drug spills, pump-malfunctions, and drug-related adverse events. Financial analysis included drug cost, resource utilization, and impact of hospital bed backfill. RESULTS: 56 patients received 219 cycles of DA-EPOCH with 193 cycles administered outpatient. Zero patients required hospitalization during outpatient administration of DA-EPOCH, resulting in 965 saved hospital days. 23 patients (41%) were hospitalized between cycles, most commonly due to neutropenic fever (52%). No extravasations were documented throughout the study period. There were few incidences of drug spills or pump malfunctions. Based on current regimen utilization, the annual transition of 84 cycles of DA-EPOCH to the outpatient setting has a positive impact on margin of $1,444,548. CONCLUSIONS: Routine outpatient administration of DA-EPOCH is both safe and feasible with a positive annual impact on margin of $1,444,548 at a comprehensive cancer center.

SHC014748M, a novel selective inhi-bitor of PI3Kδ, demonstrates promising preclinical antitumor activity in B cell lymphomas and chronic lymphocytic leukemia.

PI3Kδ (phosphatidylinositol 3-kinase-δ), one of the class I PI3Ks, is found expressed primarily in leukocytes and plays an essential role in B-cell development and function. This provides a rationale for the development of small molecule inhibitors that selectively target p110δ for patients with indolent non-Hodgkin lymphomas. Here in this paper, we comprehensively evaluated the in vitro and in vivo antitumor activity of SHC014748M, an oral selective inhibitor of PI3Kδ under Phase I clinical evaluation. Biochemical and cell-based assays were used to measure compound potency and selectivity in lymphoma cell lines as well as primary chronic lymphocytic leukemia (CLL) cells. Scid mice were subcutaneously inoculated with the SU-DHL-6 cell line. SHC014748M was more selective for PI3Kδ inhibition relative to other class I PI3K enzymes and showed in vitro activity in most of 23 B lymphoma cell lines and primary CLL cells. SHC014748M also inhibited phosphorylation of AKT, targets downstream of PI3Kδ, in both lymphoma cells and primary CLL cells. In vivo study revealed that SHC014748M significantly reduced lymphoma cell growth in the treatment group compared with control mice. CCL4, CCL17, CCL22 and CXCL13 in patient serum decreased sharply after SHC014748M treatment. According to the results, SHC014748M appeared to be a novel promising compound in the treatment of B cell lymphomas and CLL.

Role of the Transcription Factor Yin Yang 1 and Its Selectively Identified Target Survivin in High-Grade B-Cells Non-Hodgkin Lymphomas: Potential Diagnostic and Therapeutic Targets.

B-cell non-Hodgkin lymphomas (B-NHLs) are often characterized by the development of resistance to chemotherapeutic drugs and/or relapse. During drug-induced apoptosis, Yin Yang 1 (YY1) transcription factor might modulate the expression of apoptotic regulators genes. The present study was aimed to: (1) examine the potential oncogenic role of YY1 in reversing drug resistance in B-NHLs; and (2) identify YY1 transcriptional target(s) that regulate the apoptotic pathway in B-NHLs. Predictive analyses coupled with database-deposited data suggested that YY1 binds the promoter of the BIRC5/survivin anti-apoptotic gene. Gene Expression Omnibus (GEO) analyses of several B-NHL repositories revealed a conserved positive correlation between YY1 and survivin, both highly expressed, especially in aggressive B-NHLs. Further validation experiments performed in Raji Burkitt's lymphomas cells, demonstrated that YY1 silencing was associated with survivin downregulation and sensitized the cells to apoptosis. Overall, our results revealed that: (1) YY1 and survivin are positively correlated and overexpressed in B-NHLs, especially in BLs; (2) YY1 strongly binds to the survivin promoter, hence survivin may be suggested as YY1 transcriptional target; (3) YY1 silencing sensitizes Raji cells to drug-induced apoptosis via downregulation of survivin; (4) both YY1 and survivin are potential diagnostic markers and therapeutic targets for the treatment of resistant/relapsed B-NHLs.

R-DHA-oxaliplatin (R-DHAOx) versus R-DHA-cisplatin (R-DHAP) regimen in B-cell lymphoma treatment: A eight-year trajectory study.

BACKGROUND: The R-DHAP regimen (rituximab, cisplatin, dexamethasone, and high-dose cytarabine) is standardly used to treat relapsed Non-Hodgkin lymphoma (NHL). Despite scarce data, cisplatin is frequently substituted with oxaliplatin (R-DHAOx) to avoid nephrotoxicity. We compared nephrotoxicity of cisplatin and oxaliplatin based on creatinine-based trajectory modeling. METHODS: All patients with NHL treated by R-DHAP or R-DHAOx in Angers hospital between January 01, 2007, and December 31, 2014, were included. Patients received cisplatin 100 mg/m2 or oxaliplatin 130 mg/m2 (d1) with cytarabine (2000 mg/m2 , two doses, d2), dexamethasone (40 mg, d1-4), and rituximab (375 mg/m2 , d1). Creatinine levels were recorded before each cycle. Individual profiles of trajectories were clustered to detect homogeneous patterns of evolution. RESULTS: Twenty-two patients received R-DHAP, 35 R-DHAOx, 6 switched from R-DHAP to R-DHAOx due to nephrotoxicity. Characteristics of patients were similar between two groups. Patients receiving R-DHAP experienced more severe renal injury than patients receiving R-DHAOx (68% vs. 7.7%, P < .001). Two homogeneous clusters appeared: cluster A, with a majority of R-DHAOx (32, 91.4%), was less nephrotoxic than B, with a majority of R-DHAP (19, 86.4%), with a decreased average serum creatinine level (P < .0001). There were no other differences between clusters. CONCLUSIONS: Our study confirms that R-DHAOx regimen causes less nephrotoxicity than R-DHAP regimen.

[Unmittelbare Remission eines mit großzelligem B-Non-Hodgkin-Lymphom befallenen inguinalen Lymphknotens unter alleiniger homöopathischer Behandlung mit Conium: Wann ist eine alleinige adjuvant-homöopathische Tumortherapie zulässig und sinnvoll?] / Immediate Remission of an Inguinal Lymph Node Afflicted with Large-Cell B-Non-Hodgkin's Lymphoma Under Sole Homeopathic Treatment with Conium: When Is a Sole Adjuvant-Homeopathic Tumor Therapy Permissible and Useful?

Bei einer 63-jährigen Patientin wird mittels Biopsie eines linksinguinalen Lymphknotens ein großzelliges B-Non-Hodgkin-Lymphom diagnostiziert. Unmittelbar nach Beginn einer homöopathischen Therapie mit Conium C 30 beginnt sich der Lymphknoten in der linken Leiste zurückzubilden. Bei Exzision des Lymphknotens vierzehn Tage nach Therapiebeginn können histologisch keine Residuen des Tumors mehr nachgewiesen werden und es darf von einer vollständigen Remission ausgegangen werden. Die Patientin bleibt in der Folge rezidivfrei. Das homöopathische Mittel Conium (Schierling) kommt in der adjuvanten homöopathischen Tumortherapie und bei vergrößerten Lymphknoten als häufig indiziertes Mittel zur Anwendung.A large-cell B-cell non-Hodgkin Lymphoma (LCBCL) was diagnosed bioptically in a female patient (age 63 years) in one left inguinal lymph node. Immediately after beginning homeopathic treatment with Conium C 30, the lymph node started to show a reduction in size. Two weeks after starting homeopathic therapy, histological examination of the excised lymph node showed no evidence of a residual tumor ­ suggestive of a complete remission. The patient remains disease free until now. The homeopathic remedy Conium (hemlock) is frequently applied for adjuvant homeopathic tumor therapy as well as for the treatment of enlarged lymph nodes.

Is there overuse of proton pump inhibitors in B-cell non-Hodgkin lymphomas? A cohort study based on the French health insurance database in the Midi-Pyrénées region.

Patients suffering from B-cell non-Hodgkin lymphomas (B-NHL) have an increased likelihood of being exposed to proton pump inhibitors (PPIs), related to several factors which have been reported in the literature. PPIs are among the drugs most likely to be prescribed inappropriately. Consequently, B-NHL patients could be particularly at risk of inappropriate PPI prescription, with potential adverse drug reactions. We aimed to evaluate the incidence of PPIs use and to identify factors associated with PPIs initiation during the active treatment phase of B-NHL. We conducted a new-user cohort study using regional data from the French national health insurance database in the Midi-Pyrénées region (southwestern France). Incident B-NHL patients were selected according to an algorithm of selection, validated with data from a cancer registry. Our study revealed that 48.9% (95% confidence interval [CI]: 45.2-52.6) of patients initiated PPIs during chemotherapy after B-NHL diagnosis. According to information available in the SNDS, recommended indications for PPI prescriptions were identified in 21.1% of cases. Median duration of treatment was 65.3 days (CI: 35-112). Determinants of PPIs initiation were peptic ulcer disease, gastroprotection (appropriate or not) for medications considered at risk (NSAIDs, glucocorticoids and anticoagulants), age, nonfollicular lymphoma, polypharmacy, gastroenterologists' consultations and being hospitalized in a university hospital. Around 50% of patients initiated PPI treatment during the chemotherapy phase with only one-fifth identified as appropriate prescriptions and with long durations of treatment in most cases. Given this background, appropriate PPI prescription should be promoted in B-NHL to avoid potential inappropriate chronic use and related adverse events.

Human Serum Albumin-Based Drug-Free Macromolecular Therapeutics: Apoptosis Induction by Coiled-Coil-Mediated Cross-Linking of CD20 Antigens on Lymphoma B Cell Surface.

A therapeutic platform-drug-free macromolecular therapeutics (DFMT)-that induces apoptosis in B cells by cross-linking of CD20 receptors, without the need for low molecular weight cytotoxic drug, is developed. In this report, a DFMT system is synthesized and evaluated based on human serum albumin (HSA) and two complementary coiled-coil forming peptides, CCE and CCK. Fab' fragment of anti-CD20 monoclonal antibody rituximab is attached to CCE (Fab'-CCE); multiple grafts of CCK are conjugated to HSA (HSA-(CCK)7 ). The colocalization of both nanoconjugates at the surface of non-Hodgkin's lymphoma (NHL) Raji cells is demonstrated by confocal fluorescence microscopy. The colocalization leads to coiled-coil formation, CD20 cross-linking, and apoptosis induction. The apoptotic levels are evaluated by Annexin V, Caspase 3, and terminal deoxynucleotidyl transferase dUTP nick end labeling assays. Selective surface binding of DFMT to CD20+ cells is validated in experiments on a coculture of CD20+ (Raji) and CD20-(DG-75) cells. It is found that DFMT can trigger calcium influx only in Raji cells, but not in DG-75 cells. A highly specific treatment for NHL and other B cell malignancies with considerable translational potential is presented by HSA-based DFMT system.

Angelica gigas Nakai and Decursin Downregulate Myc Expression to Promote Cell Death in B-cell Lymphoma.

Angelica gigas Nakai (AGN) is an oriental traditional medicine to treat anemia, dysmenorrhea, and migraine. However, its anti-lymphoma effect is yet to be tested. Here, we demonstrated that AGN and its major component decursin target Myc to suppress lymphomagenesis in vitro and in vivo. AGN inhibited cell viability in multiple B lymphoma cells, while sparing normal splenocytes and bone marrow cells. Increased cleaved PARP level and caspase 3/7 activity and the repression of survival-promoting AKT/mTOR and MAPK pathways downstream of BCR, were responsible for the pro-apoptotic effects of AGN. We found that Myc, a prominent downstream target of these signaling pathways, contributes to AGN-induced cell death. Moreover, co-treatment with AGN and a Myc inhibitor, JQ1 or 10058-F4 yielded synergistic cytotoxic activities against cancer cells with markedly reduced Myc expression. AGN downregulated Myc expression and suppressed tumorigenesis in Eµ-myc transgenic mice. The proapoptotic activities of AGN were recapitulated by decursin, indicating that the anti-tumor effect of AGN was mainly caused by decursin. These findings suggest that AGN and decursin possess potent anti-lymphoma activity, and combination therapies with AGN/decursin and a Myc inhibitor to target Myc more efficiently could be a valuable avenue to explore in the treatment of B-cell lymphoma.

Enhancer of zeste homolog 2 (EZH2) inhibitors.

Dysregulation of the histone methyltransferase EZH2 plays a critical role in the development of a variety of malignancies including B-cell lymphomas. As a result, a series of small molecule inhibitors of EZH2 have been developed and studied in the pre-clinical setting. Three EZH2 inhibitors: tazemetostat (EPZ-6438), GSK2816126 and CPI-1205 have moved into phase I/phase II clinical trials in patients with non-Hodgkin lymphoma and genetically defined solid tumors. Early data from the tazemetostat trials indicate an acceptable safety profile and early signs of activity in diffuse large B-cell lymphoma and follicular lymphoma, including patients with EZH2 wild-type and mutant tumors. In this review, we present the rationale, key pre-clinical and early clinical findings of small molecule EZH2 inhibitors for use in lymphoma as well as future challenges and potential opportunities for combination therapies.

New insights into redox homeostasis as a therapeutic target in B-cell malignancies.

PURPOSE OF REVIEW: The goal of this review is to summarize recent advances in our understanding of the regulation of redox homeostasis and the subtype-specific role of antioxidant enzymes in B-cell-derived malignancies. Furthermore, it presents selected prooxidative therapeutic strategies against B-cell neoplasms. RECENT FINDINGS: Recent reports have shown that the disturbed redox homeostasis in B-cell malignancies is regulated by cancer-specific signaling pathways and therefore varies between the individual subtypes. For instance, in a subtype of diffuse large B-cell lymphoma with increased oxidative phosphorylation, elevated reactive oxygen species are accompanied by higher levels of thioredoxin and glutathione and inhibition of either of these systems is selectively toxic to this subtype. In addition, growing number of small molecule inhibitors targeting antioxidant enzymes, such as auranofin, SK053, adenanthin, or decreasing glutathione level, such as imexon, buthionine sulfoximine, and L-cysteinase, trigger specific cytotoxic effects against B-cell malignancies. Lastly, attention is drawn to recent reports of effective treatment modalities involving prooxidative agents and interfering with redox homeostasis provided by stromal cells. SUMMARY: Recent findings reveal important differences in redox homeostasis within the distinct subsets of B-cell-derived malignancies that can be therapeutically exploited to improve existing treatment and to overcome drug resistance.

Activity of the novel BCR kinase inhibitor IQS019 in preclinical models of B-cell non-Hodgkin lymphoma.

BACKGROUND: Pharmacological inhibition of B cell receptor (BCR) signaling has recently emerged as an effective approach in a wide range of B lymphoid neoplasms. However, despite promising clinical activity of the first Bruton's kinase (Btk) and spleen tyrosine kinase (Syk) inhibitors, a small fraction of patients tend to develop progressive disease after initial response to these agents. METHODS: We evaluated the antitumor activity of IQS019, a new BCR kinase inhibitor with increased affinity for Btk, Syk, and Lck/Yes novel tyrosine kinase (Lyn), in a set of 34 B lymphoid cell lines and primary cultures, including samples with acquired resistance to the first-in-class Btk inhibitor ibrutinib. Safety and efficacy of the compound were then evaluated in two xenograft mouse models of B cell lymphoma. RESULTS: IQS019 simultaneously engaged a rapid and dose-dependent de-phosphorylation of both constitutive and IgM-activated Syk, Lyn, and Btk, leading to impaired cell proliferation, reduced CXCL12-dependent cell migration, and induction of caspase-dependent apoptosis. Accordingly, B cell lymphoma-bearing mice receiving IQS019 presented a reduced tumor outgrowth characterized by a decreased mitotic index and a lower infiltration of malignant cells in the spleen, in tight correlation with downregulation of phospho-Syk, phospho-Lyn, and phospho-Btk. More interestingly, IQS019 showed improved efficacy in vitro and in vivo when compared to the first-in-class Btk inhibitor ibrutinib, and was active in cells with acquired resistance to this latest. CONCLUSIONS: These results define IQS019 as a potential drug candidate for a variety of B lymphoid neoplasms, including cases with acquired resistance to current BCR-targeting therapies.

Identification of apilimod as a first-in-class PIKfyve kinase inhibitor for treatment of B-cell non-Hodgkin lymphoma.

We identified apilimod as an antiproliferative compound by high-throughput screening of clinical-stage drugs. Apilimod exhibits exquisite specificity for phosphatidylinositol-3-phosphate 5-kinase (PIKfyve) lipid kinase and has selective cytotoxic activity in B-cell non-Hodgkin lymphoma (B-NHL) compared with normal cells. Apilimod displays nanomolar activity in vitro, and in vivo studies demonstrate single-agent efficacy as well as synergy with approved B-NHL drugs. Using biochemical and knockdown approaches, and discovery of a kinase domain mutation conferring resistance, we demonstrate that apilimod-mediated cytotoxicity is driven by PIKfyve inhibition. Furthermore, a critical role for lysosome dysfunction as a major factor contributing to apilimod's cytotoxicity is supported by a genome-wide CRISPR screen. In the screen, TFEB (master transcriptional regulator of lysosomal biogenesis) and endosomal/lysosomal genes CLCN7, OSTM1, and SNX10 were identified as important determinants of apilimod sensitivity. These findings thus suggest that disruption of lysosomal homeostasis with apilimod represents a novel approach to treat B-NHL.

Novel DOCK2-selective inhibitory peptide that suppresses B-cell line migration.

Dedicator of cytokinesis 2 (DOCK2) is a key molecule for lymphocyte activation and migration. DOCK2 interacts with Ras-related C3 botulinus toxin substrate 1 (Rac1, GTPase) and mediates the GDP-GTP exchange reaction, indicating that inhibitors against protein-protein interaction (PPI) between DOCK2 and Rac1 would be good drug candidates for treating immune-related disorders. Here, we report DOCK2-selective PPI inhibitory peptides discovered using random peptide T7 phage display technology. These peptides inhibited DOCK2 activity at nanomolar concentrations and were delivered to intracellular compartments by combination with cell-penetrating peptide (CPP). Consequently, one peptide, R4-DCpep-2(V2W/K4R/ox)-NH2 (Ac-RRRRCWARYHGYPWCRRRR-NH2), inhibited migration in human B lymphocyte MINO cell line at IC50 = 120 nM. To our knowledge, this is the first report of a DOCK2-selective peptide inhibitor; this study will contribute to the development of novel DOCK2-targeting immunosuppressive drugs.

Interleukin 21 - its potential role in the therapy of B-cell lymphomas.

Interleukin-21 (IL-21), a member of IL-2 cytokine family, has pleotropic biological effects on lymphoid and myeloid cells. During the past 15 years, since the discovery of IL-21, great advances have been made regarding its biological activity and the mechanisms controlling IL-21-mediated cellular responses, especially in hematological malignancies. Preclinical studies have shown that IL-21R is expressed on healthy and neoplastic B-cells and exogenous IL-21 can induce direct apoptosis of IL-21R expressing B-cell non-Hodgkin lymphomas (NHL), making it a potentially attractive anti-lymphoma therapy. However, in some hematological malignancies such as multiple myeloma, Hodgkin lymphoma and Burkitt lymphoma, IL-21 can induce proliferation of neoplastic B-cells. In NHL, the underlying mechanism of cell death was found to be different between the various subtypes, including activation of different JAK/STAT signal transduction pathways or other factors. Immunomodulatory effects of IL-21 have also been reported to contribute to its anti-tumor effects as described by earlier studies in solid tumors and B-cell associated malignancies. These effects are predominantly mediated by IL-21's ability to activate cytolytic activities by NK-cells and CD4+/CD8+ T-cells. In this review, we provide an overview of IL-21's effects in NHL, results from clinical trials utilizing IL-21, and propose how IL-21 can be therapeutically exploited for treating these lymphomas.