Immunomodulatory Drugs for the Treatment of B Cell Malignancies

Targeting the tumor microenvironment for treating double-refractory chronic lymphocytic leukemia

ABSTRACT

The introduction of BTK inhibitors and BCL2 antagonists to the treatment of chronic lymphocytic leukemia (CLL) has revolutionized therapy and improved patient outcomes. These agents have replaced chemoimmunotherapy as standard of care. Despite this progress, a new group of patients is currently emerging, which has become refractory or intolerant to both classes of agents, creating an unmet medical need. Here, we propose that the targeted modulation of the tumor microenvironment provides new therapeutic options for this group of double-refractory patients. Furthermore, we outline a sequential strategy for tumor microenvironment-directed combination therapies in CLL that can be tested in clinical protocols.

Immunomodulatory drugs: a promising clinical ally for cancer immunotherapy

While immunomodulatory imide drugs (IMiDs) have been authorised for treatment of haematological cancers for over two decades, the appreciation of their ability to stimulate antitumour T cell and natural killer (NK) cell responses is relatively recent. Clinical trial data increasingly show that targeted immunotherapies, such as antibodies, T cells, and vaccines, improve outcomes when delivered in combination with the IMiD derivatives lenalidomide or pomalidomide. Here, we review these clinical data to highlight the relevance of IMiDs in combinatorial immunotherapy for both haematological and solid tumours. Further research into the molecular mechanisms of IMiDs and an increased understanding of their immunomodulatory effects may refine the specific applications of IMiDs and improve the design of future clinical trials, moving IMiDs to the forefront of combinatorial cancer immunotherapy.

Updates of primary central nervous system lymphoma

Lymphoma occurring in the central nervous system is considered primary central nervous system lymphoma (PCNSL), usually without systematic lesions. Over the last few decades, a deep understanding of PCNSL has been lacking due to the low incidence rate, and the overall survival and progression-free survival of patients with PCNSL are lower than those with other types of non-Hodgkin lymphoma. Recently, there have been several advancements in research on PCNSL. Advances in diagnosis of the disease are primarily reflected in the promising diagnostic efficiency of novel biomarkers. Pathogenesis mainly involves abnormal activation of nuclear factor kappa-B signaling pathways, copy number variations, and DNA methylation. Novel therapies such as Bruton's tyrosine kinase inhibitors, immunomodulatory drugs, immune checkpoint inhibitors, and phosphoinositide 3-kinase/mammalian target of rapamycin inhibitors are being evaluated as possible treatment options for PCNSL, especially for relapsed/refractory (R/R) cases. Several clinical trials also indicated the promising feasibility and efficacy of chimeric antigen receptor T-cell therapy for selected R/R PCNSL patients. This review focuses on discussing recent updates, including the diagnosis, pathogenesis, and novel therapy of PCNSL.

Synergy between BRD9- and IKZF3-Targeting as a Therapeutic Strategy for Multiple Myeloma

Progress in the treatment of multiple myeloma (MM) has resulted in improvement in the survival rate. However, there is still a need for more efficacious and tolerated therapies. We and others have shown that bromodomain-containing protein 9 (BRD9), a member of the non-canonical SWI/SNF chromatin remodeling complex, plays a role in MM cell survival, and targeting BRD9 selectively blocks MM cell proliferation and synergizes with IMiDs. We found that synergy in vitro is associated with the downregulation of MYC and Ikaros proteins, including IKZF3, and overexpression of IKZF3 or MYC could partially reverse synergy. RNA-seq analysis revealed synergy to be associated with the suppression of pathways associated with MYC and E2F target genes and pathways, including cell cycle, cell division, and DNA replication. Stimulated pathways included cell adhesion and immune and inflammatory response. Importantly, combining IMiD treatment and BRD9 targeting, which leads to the downregulation of MYC protein and upregulation of CRBN protein, was able to override IMiD resistance of cells exposed to iberdomide in long-term culture. Taken together, our results support the notion that combination therapy based on agents targeting BRD9 and IKZF3, two established dependencies in MM, represents a promising novel therapeutic strategy for MM and IMiD-resistant disease.

Chimeric Antigen Receptor (CAR)-T Cell Therapy for Non-Hodgkin's Lymphoma

This review focuses on the use of chimeric antigen receptor (CAR)-T cell therapy to treat non-Hodgkin's lymphoma (NHL), a classification of heterogeneous malignant neoplasms of the lymphoid tissue. Despite various conventional and multidrug chemotherapies, the poor prognosis for NHL patients remains and has prompted the utilization of groundbreaking personalized therapies such as CAR-T cells. CAR-T cells are T cells engineered to express a CAR that enables T cells to specifically lyse tumor cells with extracellular expression of a tumor antigen of choice. A CAR is composed of an extracellular antibody fragment or target protein binding domain that is conjugated to activating intracellular signaling motifs common to T cells. In general, CAR-T cell therapies for NHL are designed to recognize cellular markers ubiquitously expressed on B cells such as CD19+, CD20+, and CD22+. Clinical trials using CAR-T cells such as ZUMA-7 and TRANSFORM demonstrated promising results compared to standard of care and ultimately led to FDA approval for the treatment of relapsed/refractory NHL. Despite the success of CAR-T therapy for NHL, challenges include adverse side effects as well as extrinsic and intrinsic mechanisms of tumor resistance that lead to suboptimal outcomes. Overall, CAR-T cell therapies have improved clinical outcomes in NHL patients and generated optimism around their future applications.

FPFT-2216, a Novel Anti-lymphoma Compound, Induces Simultaneous Degradation of IKZF1/3 and CK1α to Activate p53 and Inhibit NFκB Signaling

Reducing casein kinase 1α (CK1α) expression inhibits the growth of multiple cancer cell lines, making it a potential therapeutic target for cancer. Herein, we evaluated the antitumor activity of FPFT-2216-a novel low molecular weight compound-in lymphoid tumors and elucidated its molecular mechanism of action. In addition, we determined whether targeting CK1α with FPFT-2216 is useful for treating hematopoietic malignancies. FPFT-2216 strongly degraded CK1α and IKAROS family zinc finger 1/3 (IKZF1/3) via proteasomal degradation. FPFT-2216 exhibited stronger inhibitory effects on human lymphoma cell proliferation than known thalidomide derivatives and induced upregulation of p53 and its transcriptional targets, namely, p21 and MDM2. Combining FPFT-2216 with an MDM2 inhibitor exhibited synergistic antiproliferative activity and induced rapid tumor regression in immunodeficient mice subcutaneously transplanted with a human lymphoma cell line. Nearly all tumors in mice disappeared after 10 days; this was continuously observed in 5 of 7 mice up to 24 days after the final FPFT-2216 administration. FPFT-2216 also enhanced the antitumor activity of rituximab and showed antitumor activity in a patient-derived diffuse large B-cell lymphoma xenograft model. Furthermore, FPFT-2216 decreased the activity of the CARD11/BCL10/MALT1 (CBM) complex and inhibited IκBα and NFκB phosphorylation. These effects were mediated through CK1α degradation and were stronger than those of known IKZF1/3 degraders. In conclusion, FPFT-2216 inhibits tumor growth by activating the p53 signaling pathway and inhibiting the CBM complex/NFκB pathway via CK1α degradation. Therefore, FPFT-2216 may represent an effective therapeutic agent for hematopoietic malignancies, such as lymphoma.

SIGNIFICANCE

We found potential vulnerability to CK1α degradation in certain lymphoma cells refractory to IKZF1/3 degraders. Targeting CK1α with FPFT-2216 could inhibit the growth of these cells by activating p53 signaling. Our study demonstrates the potential therapeutic application of CK1α degraders, such as FPFT-2216, for treating lymphoma.

Zanubrutinib-lenalidomide-rituximab (ZR2) in unfit diffuse large B-cell lymphoma: efficient and tolerant

The objective of this study is to examine the effectiveness and safety of zanubrutinib, rituximab, and lenalidomide (ZR2) in unfit patients with diffuse large B-cell lymphoma (DLBCL). Thrombosis or bleeding risk of ZR2 regimen, especially when antiplatelet agents were co-prescribed, was also evaluated. We retrospectively reviewed unfit newly diagnosed (ND) and refractory or relapsed (R/R) patients with DLBCL who were administered with ZR2 regimen in two medical centers between December 2019 and February 2022. Response rates, progression-free survival (PFS), overall survival (OS), bleeding adverse events (AEs), and thrombosis episodes were analyzed. Furthermore, we investigated the effects of zanubrutinib alone or in combination with lenalidomide on platelet functions in vitro and in vivo. A total of 30 unfit patients (13 ND DLBCL and 17 R/R DLBCL patients) who received ZR2 regimen were enrolled in the study (median age: 69.5 years). The ultimate ORRs for the ND DLBCL and R/R DLBCL were 77.0% and 50.1%, respectively. The median follow-up was 16.6 months. The median PFS and OS were not achieved during the follow-up time. Subcutaneous hemorrhage AEs occurred in four cases, three cases suffered severe bleeding events, and thrombosis events were observed in two patients. ZR2 regimen inhibited platelet functions (aggregation, clot retraction, spreading and activation) in vitro and in vivo function testing especially in response to collagen. ZR2 is an efficient treatment option for unfit patients with DLBCL and could be well tolerated. Notably, this regimen inhibited platelet functions. Antiplatelet agents should be used with caution in patients treated with this regimen.

Population pharmacokinetics of lenalidomide in Chinese patients with influence of genetic polymorphisms of ABCB1

Affected by differences in the pharmacokinetics (PK) of lenalidomide, the toxicity of lenalidomide varies among different patients, with serious toxicity leading to dose reduction or discontinuation. The differences in the PK of lenalidomide may be related to factors such as patients' physiological characteristics, pathological characteristics and gene polymorphisms etc., which may also affect its toxicity. The aim of this study is to establish a population pharmacokinetic (PPK) model of lenalidomide and explore factors associated with the adverse events (AEs) of lenalidomide from a PK perspective. Blood samples were collected by opportunistic blood collection. Drug concentrations were determined by using HPLC/MS and genotype of ABCB1 3435 C > T (rs1045642), ABCB1 1236 A > G (rs1128503) and ABCB1 2677 A > C/T (rs2032582) was tested by the first-generation DNA sequencing technology. NONMEM software and SPSS 26.0 software were used respectively to establish PPK model of lenalidomide and explore the correlation between PK parameters and the incidence of serious AEs of lenalidomide. 51 patients were enrolled in the PPK study, and one-compartment model with first-order absorption and elimination agreed well with the observed data. The significant covariate affecting lenalidomide apparent volume of distribution (V/F) were the gene polymorphism of ABCB1 3435 C > T and diet. Safety studies could be conducted in 39 patients. The V/F value in patients suffering from serious AEs was significantly higher than that in others ( median = 67.04 L vs 37.17 L, P = 0.033). According to the covariates screened, the incidence of serious AEs was higher in patients with genotype CT or TT at ABCB1 3435 C > T locus than that in patients with genotype CC (P = 0.039). Additionally, V/F value was the highest in patients carrying genotype TT with postprandial medication, in whom the incidence of serious AEs was higher than others (P = 0.037). In conclusion, the genotype of ABCB1 3435 C > T locus and diet had pharmacokinetically relevant impact on lenalidomide, which may also be related to the incidence of serious AEs. Patients with gene variants of CT or TT at ABCB1 3435 C > T locus may be more susceptible to serious AEs, and monitoring of adverse reactions should be particularly strengthened in patients who carried genotype TT with postprandial medication.

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.

Reprogramming of Treg cells in the inflammatory microenvironment during immunotherapy: a literature review

Regulatory T cells (Treg), as members of CD4+ T cells, have garnered extensive attention in the research of tumor progression. Treg cells have the function of inhibiting the immune effector cells, preventing tissue damage, and suppressing inflammation. Under the stimulation of the tumor inflammatory microenvironment (IM), the reprogramming of Treg cells enhances their suppression of immune responses, ultimately promoting tumor immune escape or tumor progression. Reducing the number of Treg cells in the IM or lowering the activity of Treg cells while preventing their reprogramming, can help promote the body's anti-tumor immune responses. This review introduces a reprogramming mechanism of Treg cells in the IM; and discusses the regulation of Treg cells on tumor progression. The control of Treg cells and the response to Treg inflammatory reprogramming in tumor immunotherapy are analyzed and countermeasures are proposed. This work will provide a foundation for downregulating the immunosuppressive role of Treg in the inflammatory environment in future tumor immunotherapy.

New hopes in relapsed refractory primary central nervous system lymphoma

PURPOSE OF REVIEW

Patients with relapsed/refractory primary central nervous system lymphoma (rrPCNSL) have poor prognosis, with a median survival after relapse of 6.8 months. In this review, we discuss the evolving landscape and the possible future directions related to this important unmet clinical need.

RECENT FINDINGS

The modern two-phase approach for newly diagnosed PCNSL based on an induction using high-dose methotrexate (HD-MTX) combinations and a subsequent consolidation, has significantly improved the outcome in this setting. However, this strategy is able to cure more or less 50% of patients. rrPCNSL patients have a very poor prognosis with a reported 5-year overall survival of 18%. Late relapses (after third year) and use of high-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT) represent important factors associated with a better outcome in this setting. On the basis of the growing acquisition of knowledge on the molecular characteristics of PCNSL, the use of non-chemotherapeutic drugs such as bruton tyrosine kinase inhibitors (BTK-is), immunomodulatory drugs (IMiDs) and immune checkpoint blockers (ICBs) is increasing in the last years along with the introduction of novel approaches (CAR-T cells and blood--brain barrier disruption). However, despite high responses in some cases, durations are often short, translating in outcome results still unsatisfactory.

SUMMARY

Treatment of rrPCNSL patients is challenging. As no standard of care exist in this setting, it is of paramount importance to acquire new knowledge related to this condition and start multidisciplinary collaboration in order to improve pts outcome.

Beyond Bruton's tyrosine kinase inhibitors in mantle cell lymphoma: bispecific antibodies, antibody-drug conjugates, CAR T-cells, and novel agents

Mantle cell lymphoma is a B cell non-Hodgkin lymphoma (NHL), representing 2-6% of all NHLs and characterized by overexpression of cyclin D1. The last decade has seen the development of many novel treatment approaches in MCL, most notably the class of Bruton's tyrosine kinase inhibitors (BTKi). BTKi has shown excellent outcomes for patients with relapsed or refractory MCL and is now being studied in the first-line setting. However, patients eventually progress on BTKi due to the development of resistance. Additionally, there is an alteration in the tumor microenvironment in these patients with varying biological and therapeutic implications. Hence, it is necessary to explore novel therapeutic strategies that can be effective in those who progressed on BTKi or potentially circumvent resistance. In this review, we provide a brief overview of BTKi, then discuss the various mechanisms of BTK resistance including the role of genetic alteration, cancer stem cells, tumor microenvironment, and adaptive reprogramming bypassing the effect of BTK inhibition, and then provide a comprehensive review of current and emerging therapeutic options beyond BTKi including novel agents, CAR T cells, bispecific antibodies, and antibody-drug conjugates.

The progress of novel strategies on immune-based therapy in relapsed or refractory diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) can be cured with standard front-line immunochemotherapy, whereas nearly 30-40% of patients experience refractory or relapse. For several decades, the standard treatment strategy for fit relapsed/refractory (R/R) DLBCL patients has been high-dose chemotherapy followed by autologous hematopoietic stem cell transplant (auto-SCT). However, the patients who failed in salvage treatment or those ineligible for subsequent auto-SCT have dismal outcomes. Several immune-based therapies have been developed, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engaging antibodies, chimeric antigen receptor T-cells, immune checkpoint inhibitors, and novel small molecules. Meanwhile, allogeneic SCT and radiotherapy are still necessary for disease control for fit patients with certain conditions. In this review, to expand clinical treatment options, we summarize the recent progress of immune-related therapies and prospect the future indirections in patients with R/R DLBCL.

Pharmacologic targeting of Nedd8-activating enzyme reinvigorates T-cell responses in lymphoid neoplasia

Neddylation is a sequential enzyme-based process which regulates the function of E3 Cullin-RING ligase (CRL) and thus degradation of substrate proteins. Here we show that CD8+ T cells are a direct target for therapeutically relevant anti-lymphoma activity of pevonedistat, a Nedd8-activating enzyme (NAE) inhibitor. Pevonedistat-treated patient-derived CD8+ T cells upregulated TNFα and IFNγ and exhibited enhanced cytotoxicity. Pevonedistat induced CD8+ T-cell inflamed microenvironment and delayed tumor progression in A20 syngeneic lymphoma model. This anti-tumor effect lessened when CD8+ T cells lost the ability to engage tumors through MHC class I interactions, achieved either through CD8+ T-cell depletion or genetic knockout of B2M. Meanwhile, loss of UBE2M in tumor did not alter efficacy of pevonedistat. Concurrent blockade of NAE and PD-1 led to enhanced tumor immune infiltration, T-cell activation and chemokine expression and synergistically restricted tumor growth. shRNA-mediated knockdown of HIF-1α, a CRL substrate, abrogated the in vitro effects of pevonedistat, suggesting that NAE inhibition modulates T-cell function in HIF-1α-dependent manner. scRNA-Seq-based clinical analyses in lymphoma patients receiving pevonedistat therapy demonstrated upregulation of interferon response signatures in immune cells. Thus, targeting NAE enhances the inflammatory T-cell state, providing rationale for checkpoint blockade-based combination therapy.

Suspected Immune Thrombocytopenic Purpura Induced by Lenalidomide for the Treatment of Myelodysplastic Syndrome with Deletion of Chromosome 5q: A Case Report

Lenalidomide (LEN), one of the key drugs in the treatment of myelodysplastic syndromes (MDS) with 5q deletion, as well as multiple myeloma (MM), has various immunomodulatory effects and has been associated with autoimmune diseases, including immune thrombocytopenic purpura (ITP). A 78-year-old man presented with pancytopenia and was diagnosed with MDS with 5q deletion and other chromosomal abnormalities. Two cycles of LEN therapy (one cycle: 10 mg/day for 21 days) resulted in a transient improvement in anemia, followed by MDS progression with severe thrombocytopenia (4 × 10⁹/L) refractory to platelet transfusions. As other non-immune and alloimmune causes of transfusion-refractory thrombocytopenia were excluded, and the level of platelet-associated immunoglobulin G was extremely high compared with the level before treatment with LEN, the diagnosis of ITP was highly suspected. Despite treatment with prednisolone (PSL), eltrombopag, and repeated platelet transfusions, his platelet count did not increase, and he died of a gastrointestinal hemorrhage. Several cases of ITP induced by LEN used to treat MM had been reported, but the platelet count recovered after administration of PSL in these previous cases. However, we should be mindful of using LEN for patients with MDS because its treatment may become extremely difficult if ITP develops.

Targeting cereblon in hematologic malignancies

The protein cereblon (CRBN) is a substrate receptor of the cullin 4-really interesting new gene (RING) E3 ubiquitin ligase complex CRL4^CRBN. Targeting CRBN mediates selective protein ubiquitination and subsequent degradation via the proteasome. This review describes novel thalidomide analogs, immunomodulatory drugs, also known as CRBN E3 ubiquitin ligase modulators or molecular glues (avadomide, iberdomide, CC-885, CC-90009, BTX-1188, CC-92480, CC-99282, CFT7455, and CC-91633), and CRBN-based proteolysis targeting chimeras (PROTACs) with increased efficacy and potent activity for application in hematologic malignancies. Both types of CRBN-binding drugs, molecular glues, and PROTACs stimulate the interaction between CRBN and its neosubstrates, recruiting target disease-promoting proteins and the E3 ubiquitin ligase CRL4^CRBN. Proteins that are traditionally difficult to target (transcription factors and oncoproteins) can be polyubiquitinated and degraded in this way. The competition of CRBN neosubstrates with endogenous CRBN-interacting proteins and the pharmacology and rational combination therapies of and mechanisms of resistance to CRL4^CRBN modulators or CRBN-based PROTACs are described.

Reshaping the tumor microenvironment: The versatility of immunomodulatory drugs in B-cell neoplasms

Immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide and pomalidomide are antitumor compounds that have direct tumoricidal activity and indirect effects mediated by multiple types of immune cells in the tumor microenvironment (TME). IMiDs have shown remarkable therapeutic efficacy in a set of B-cell neoplasms including multiple myeloma, B-cell lymphomas and chronic lymphocytic leukemia. More recently, the advent of immunotherapy has revolutionized the treatment of these B-cell neoplasms. However, the success of immunotherapy is restrained by immunosuppressive signals and dysfunctional immune cells in the TME. Due to the pleiotropic immunobiological properties, IMiDs have shown to generate synergetic effects in preclinical models when combined with monoclonal antibodies, immune checkpoint inhibitors or CAR-T cell therapy, some of which were successfully translated to the clinic and lead to improved responses for both first-line and relapsed/refractory settings. Mechanistically, despite cereblon (CRBN), an E3 ubiquitin ligase, is considered as considered as the major molecular target responsible for the antineoplastic activities of IMiDs, the exact mechanisms of action for IMiDs-based TME re-education remain largely unknown. This review presents an overview of IMiDs in regulation of immune cell function and their utilization in potentiating efficacy of immunotherapies across multiple types of B-cell neoplasms.

Recent Updates on the Development of Deuterium-Containing Drugs for the Treatment of Cancer

Cancer is one of the deadliest diseases in the world. In 2020, 19.3 million cancer cases and 10 million deaths were reported in the world. It is supposed that the prevalence of cancer cases will rise to 28.4 million by 2040. Chemotherapy-based regimens have a narrow therapeutic index, severe adverse drug reactions, and lack metabolic stability. Besides, the metabolism of anticancer produces several non-active and toxic metabolites that reduce exposure of the target site to the parent drug. Therefore, developing better-tolerated and effective new anticancer drugs and modification of the existing anticancer drugs to minimize toxicity and increase efficacy has become a very urgent need. Deuterium incorporation reduces the metabolism of certain drugs that are breakdown by pathways involving hydrogen-carbon bond scission. For example, CYP450 mediated oxidative metabolism of drugs that involves the breakdown of a hydrogen-carbon bond affected by deuteration. Deuterium incorporation into the drug increases the half-life and reduces the dose, which provides better safety and efficacy. Deutetrabenazine is the first deuterated form of tetrabenazine approved to treat chorea associated with Huntington’s disease and tardive dyskinesia. The study revealed that Deutetrabenazine has fewer neuropsychiatric side effects with favorable safety than tetrabenazine. The current review highlights the deuterium kinetic isotope effect on drug metabolism, deuterated compound pharmacokinetic property, and safety profile. Besides, this review explains the deuterated anticancer drug development update status.

SOHO State of the Art Updates and Next Questions: Managing Relapsed Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin lymphoma i.e., incurable with current therapies. While some patients experience prolonged remissions following initial therapy, most will have a relapsing-remitting course requiring several lines of treatment over the course of their disease. Several targeted therapies are now available to treat patients with relapsed MCL. The Bruton's tyrosine kinase (BTK) inhibitors, including ibrutinib, acalabrutinib, and zanubrutinib, are highly active in MCL and currently approved for treating patients with relapsed disease. Bortezomib and lenalidomide are available as monotherapy or in combination with other agents. Venetoclax is active and can be considered for use in relapsed MCL, although it is not currently approved by regulatory agencies. Chimeric antigen receptor T-cell (CAR-T) therapy with brexucabtagene autoleucel yields high response rates and is now approved for patients with relapsed MCL. Allogeneic stem cell transplant remains an option for a small subset of medically fit and motivated patients who have progressed through multiple lines of therapy, although its use is limited by substantial toxicity. There is currently no standard approach to sequencing therapies for patients with relapsed MCL, and the ability to utilize disease biologic and clinical characteristics to guide treatment decisions in this setting remains limited. In this review, we summarize the current evidence to guide the management of patients with relapsed MCL, review emerging agents and combination therapies that are under investigation, and outline our current treatment approach for these patients.

Regulatory T cells (Tregs) in lymphoid malignancies and the impact of novel therapies

Regulatory T cells (Tregs) are responsible for maintaining immune homeostasis by controlling immune responses. They can be characterized by concomitant expression of FoxP3, CD25 and inhibitory receptors such as PD-1 and CTLA-4. Tregs are key players in preventing autoimmunity and are dysregulated in cancer, where they facilitate tumor immune escape. B-cell lymphoid malignancies are a group of diseases with heterogenous molecular characteristics and clinical course. Treg levels are increased in patients with B-cell lymphoid malignancies and correlate with clinical outcomes. In this review, we discuss studies investigating Treg immunobiology in B-cell lymphoid malignancies, focusing on clinical correlations, mechanisms of accumulation, phenotype, and function. Overarching trends suggest that Tregs can be induced directly by tumor cells and recruited to the tumor microenvironment where they suppress antitumor immunity to facilitate disease progression. Further, we highlight studies showing that Tregs can be modulated by novel therapeutic agents such as immune checkpoint blockade and targeted therapies. Treg disruption by novel therapeutics may beneficially restore immune competence but has been associated with occurrence of adverse events. Strategies to achieve balance between these two outcomes will be paramount in the future to improve therapeutic efficacy and safety.

High-Throughput CRISPR Screening in Hematological Neoplasms

CRISPR is becoming an indispensable tool in biological research, revolutionizing diverse fields of medical research and biotechnology. In the last few years, several CRISPR-based genome-targeting tools have been translated for the study of hematological neoplasms. However, there is a lack of reviews focused on the wide uses of this technology in hematology. Therefore, in this review, we summarize the main CRISPR-based approaches of high throughput screenings applied to this field. Here we explain several libraries and algorithms for analysis of CRISPR screens used in hematology, accompanied by the most relevant databases. Moreover, we focus on (1) the identification of novel modulator genes of drug resistance and efficacy, which could anticipate relapses in patients and (2) new therapeutic targets and synthetic lethal interactions. We also discuss the approaches to uncover novel biomarkers of malignant transformations and immune evasion mechanisms. We explain the current literature in the most common lymphoid and myeloid neoplasms using this tool. Then, we conclude with future directions, highlighting the importance of further gene candidate validation and the integration and harmonization of the data from CRISPR screening approaches.

Inside-Out of Complement in Cancer

The role of complement in cancer has received increasing attention over the last decade. Recent studies provide compelling evidence that complement accelerates cancer progression. Despite the pivotal role of complement in fighting microbes, complement seems to suppress antitumor immunity via regulation of host cell in the tumor microenvironment. Although most studies link complement in cancer to complement activation in the extracellular space, the discovery of intracellular activation of complement, raises the question: what is the relevance of this process for malignancy? Intracellular activation is pivotal for the survival of immune cells. Therefore, complement can be important for tumor cell survival and growth regardless of the role in immunosuppression. On the other hand, because intracellular complement (the complosome) is indispensable for activation of T cells, these functions will be essential for priming antitumor T cell responses. Here, we review functions of complement in cancer with the consideration of extra and intracellular pathways of complement activation and spatial distribution of complement proteins in tumors and periphery and provide our take on potential significance of complement as biomarker and target for cancer therapy.

Tumor Microenvironment and Immunotherapy-Based Approaches in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma (NHL) characterized by the translocation t(11;14) (q13;q32) and a poor response to rituximab–anthracycline-based chemotherapy. High-dose cytarabine-based regimens offer a durable response, but an important number of MCL patients are not eligible for intensive treatment and are ideal candidates for novel targeted therapies (such as BTK, proteasome or BCL2 inhibitors, Immunomodulatory Drugs (IMiDs), bispecific antibodies, or CAR-T cell therapy). On the bench side, several studies aiming to integrate the tumor within its ecosystem highlighted a critical role of the tumor microenvironment (TME) in the expansion and resistance of MCL. This led to important insights into the role of the TME in the management of MCL, including potential targets and biomarkers. Indeed, targeted agents often have a combined mechanism of action on the tumor B cell but also on the tumor microenvironment. The aim of this review is to briefly describe the current knowledge on the biology of the TME in MCL and expose the results of the different therapeutic strategies integrating the TME in this disease.

Targeted protein degradation: from small molecules to complex organelles-a Keystone Symposia report

Targeted protein degradation is critical for proper cellular function and development. Protein degradation pathways, such as the ubiquitin proteasomes system, autophagy, and endosome-lysosome pathway, must be tightly regulated to ensure proper elimination of misfolded and aggregated proteins and regulate changing protein levels during cellular differentiation, while ensuring that normal proteins remain unscathed. Protein degradation pathways have also garnered interest as a means to selectively eliminate target proteins that may be difficult to inhibit via other mechanisms. On June 7 and 8, 2021, several experts in protein degradation pathways met virtually for the Keystone eSymposium "Targeting protein degradation: from small molecules to complex organelles." The event brought together researchers working in different protein degradation pathways in an effort to begin to develop a holistic, integrated vision of protein degradation that incorporates all the major pathways to understand how changes in them can lead to disease pathology and, alternatively, how they can be leveraged for novel therapeutics.