Human Diffuse Large B-cell Lymphoma Research Articles

EZB-type diffuse large B-cell lymphoma cell lines have superior migration capabilities compared to MCD-type.

Diffuse large B-cell lymphoma (DLBCL) represents the most prevalent aggressive B-cell lymphoma. The group is heterogeneous and the outcome is variable. A variety of approaches have been employed with the objective of improving the stratification of DLBCL patients according to their prognosis, based on the cell of origin. Recently, distinct genetic subtypes of DLBCL have been identified. Given the importance of cell migration in immune cells, the objective of this study was to ascertain whether different genetic subtypes of DLBCL exhibit disparate migration abilities. MCD- and EZB-type DLBCL cell lines were subjected to testing to ascertain their basal velocity in straight microchannels and their ability to overcome tight constrictions of 2 μm. The EZB-type cell lines showed superior basal migration velocity and constriction passage time, and a similar trend was observed in live cell imaging of native human DLBCL tissue. In addition, MCD-type DLBCL exhibited significantly elevated levels of nuclear lamin A/C, which is responsible for the stiffness of the nuclear envelope and could thus explain the disparate migration behaviours observed among these subtypes. Our study suggests that different genetic subtypes of DLBCL may not only influence the outcome after therapy but also the motility of the tumour cells.

Development of New Diffuse Large B Cell Lymphoma Mouse Models.

Diffuse large B cell lymphoma (DLBCL) is the most diagnosed, aggressive non-Hodgkin lymphoma, with ~40% of patients experiencing refractory or relapsed disease. Given the low response rates to current therapy, alternative treatment strategies are necessary to improve patient outcomes. Here, we sought to develop an easily accessible new xenograft mouse model that better recapitulates the human disease for preclinical studies. We generated two Luciferase (Luc)-EGFP-expressing human DLBCL cell lines representing the different DLBCL cell-of-origin subtypes. After intravenous injection of these cells into humanized NSG mice, we monitored the tumor growth and evaluated the organ-specific engraftment/progression period. Our results showed that human IL6-expressing NSG (NSG-IL6) mice were highly permissive for DLBCL cell growth. In NSG-IL6 mice, systemic engraftments of both U2932 activated B cell-like- and VAL germinal B cell-like-DLBCL (engraftment rate; 75% and 82%, respectively) were detected within 2nd-week post-injection. In the organ-specific ex vivo evaluation, both U2932-Luc and VAL-Luc cells were initially engrafted and expanded in the spleen, liver, and lung and subsequently in the skeleton, ovary, and brain. Consistent with the dual BCL2/MYC translocation association with poor patient outcomes, VAL cells showed heightened proliferation in human IL6-conditioned media and caused rapid tumor expansion and early death in the engrafted mice. We concluded that the U2932 and VAL cell-derived human IL6-expressing mouse models reproduced the clinical features of an aggressive DLBCL with a highly consistent pattern of tumor development. Based on these findings, NSG mice expressing human IL6 have the potential to serve as a new tool to develop DLBCL xenograft models to overcome the limitations of standard subcutaneous DLBCL xenografts.

Low NDRG2, regulated by the MYC/MIZ-1 complex and methylation, predicts poor outcomes in DLBCL patients.

Diffuse large B-cell lymphoma (DLBCL) represents the most common tumor in non-Hodgkin's lymphoma. N-Myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor highly expressed in healthy tissues but downregulated in many cancers. Although cell proliferation-related metabolism rewiring has been well characterized, less is known about the mechanism of metabolic changes with DLBCL. Herein, we investigated the expressions of NDRG2, MYC and Myc-interacting zinc finger protein 1 (MIZ-1) in seven human lymphoma (mostly DLBCLs) cell lines. NDRG2 expression was inversely correlated with the expressions of MYC and MIZ-1. Further, we explored the regulatory mechanism and biological functions underlying the lymphomagenesis involving NDRG2, MYC and MIZ-1. MYC and MIZ-1 promoted DLBCL cell proliferation, while NDRG2 induced apoptosis in LY8 cells. Moreover, NDRG2 methylation was reversed by the 5-Aza-2'-deoxycytidine (5-Aza-CDR) treatment, triggering the downregulation of MYC and inhibiting DLBCL cell survival. MYC interacts with NDRG2 to regulate energy metabolism associated with mTOR. Remarkably, supporting the biological significance, the converse correlation between NDRG2 and MYC was observed in human DLBCL tumor tissues (R = -0.557). Bioinformatics analysis further validated the association among NDRG2, MYC, MIZ-1, mTOR, and related metabolism genes. Additionally, NDRG2 (P = 0.001) and MYC (P < 0.001) were identified as promising prognostic biomarkers in DLBCL patients through survival analysis. Together, our data demonstrate that the MYC/MIZ-1 complex interplays with NDRG2 to influence the proliferation and apoptosis of DLBCL cells and show the characterizations of NDRG2, MYC and MIZ-1 for metabolism features and prediction prognosis in DLBCL.

Abstract B008: Utilizing pathway incompatibility for synthetic lethality: A therapeutic strategy for B-cell lymphoma

Abstract Previous pan-cancer analyses revealed co-occurring mutations exploitable for combination therapies and mutually exclusive mutations assumed to reflect functional redundancy (Mina M et al. 2017; Sanchez-Vega F et al. 2018). However, we recently highlighted an alternative scenario when mutual exclusivity reflects the incapability of two pathways to function together, a phenomenon we term “pathway incompatibility” (Chan LN et al. 2020). We found that STAT5-and ERK-activating genetic lesions were not only mutually exclusive in B-ALL cases, but also reciprocally inhibited each other at the signal transduction level, inducing cell death instead of promoting leukemogenesis. Notably, we demonstrated, for the first time, that pharmacological activation of STAT5 in ERK-driven B-ALL cells and ERK in STAT5-driven B-ALL cells represents a tractable synthetic lethality (Chan LN et al. 2020). We now take the important next step of identifying potential candidates for synthetic lethal genetic interactions resulting from pathway incompatibility in B-cell malignancies more broadly. Diffuse large B-cell lymphoma (DLBCL) is a rapidly growing blood cancer affecting older adults and constituting about 25% of all lymphoma cases in the US. Around 40% of patients develop relapsed or refractory DLBCL (Pfreundschuh M et al. 2006; Ngu H et al. 2022). Thus, there is an unmet need to develop new therapeutic strategies to improve clinical outcomes. Studying 1684 DLBCL cases from published datasets, we found that about 30% of DLBCL cases carry loss-of-function (LOF) CBP or gain-of-function (GOF) MYD88 genetic lesions. CBP encodes a histone acetyltransferase and, together with p300, functions as a transcriptional coactivator and tumor suppressor. Conversely, GOF MYD88 mutations drive lymphomagenesis by regulating kinases and transcription factors. Our analysis revealed that LOF CBP and GOF MYD88 genetic lesions co-occurred less frequently than expected by chance (odds ratio: 0.57, P=0.0), indicating their mutual exclusivity. Experiments with human DLBCL cell lines expressing wild-type MYD88 and CBP showed that CBP/p300 inhibitors did not impact cell viability. However, cells expressing a GOF MYD88 mutant or stimulated with a toll-like receptor (TLR) agonist to activate MYD88 became sensitized to CBP/p300 inhibitors, resulting in cell death. This suggests that LOF CBP and GOF MYD88 are incompatible for cell survival, with their co-occurrence resulting in synthetic lethality. We then tested a synthetic lethality-based therapeutic concept based on CBP-MYD88 incompatibility in DLBCL. We found that MYD88-mutated DLBCL cell lines were more sensitive to pharmacological inhibition of CBP/p300, while CBP-deficient DLBCL cell lines showed increased sensitivity to TLR agonist treatment. In summary, we identified mutual exclusivity between LOF CBP and GOF MYD88 lesions in DLBCL, where their co-occurrence induces cell death. Moreover, we demonstrated the therapeutic potential of synthetic lethality resulting from co-introduction of LOF CBP and GOF MYD88 in DLBCL. Citation Format: Mia Knupke, Lai Chan. Utilizing pathway incompatibility for synthetic lethality: A therapeutic strategy for B-cell lymphoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr B008.

Genome-scale clustered regularly interspaced short palindromic repeats screen identifies nucleotide metabolism as an actionable therapeutic vulnerability in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common malignancy that develops in patients with ataxia-telangiectasia, a cancer-predisposing inherited syndrome characterized by inactivating germline ATM mutations. ATM is also frequently mutated in sporadic DLBCL. To investigate lymphomagenic mechanisms and lymphoma-specific dependencies underlying defective ATM, we applied ribonucleic acid (RNA)-seq and genome-scale loss-offunction clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 screens to systematically interrogate B-cell lymphomas arising in a novel murine model (Atm-/-nu-/-) with constitutional Atm loss, thymic aplasia but residual T-cell populations. Atm-/-nu-/-lymphomas, which phenotypically resemble either activated B-cell-like or germinal center Bcell-like DLBCL, harbor a complex karyotype, and are characterized by MYC pathway activation. In Atm-/-nu-/-lymphomas, we discovered nucleotide biosynthesis as a MYCdependent cellular vulnerability that can be targeted through the synergistic nucleotidedepleting actions of mycophenolate mofetil (MMF) and the WEE1 inhibitor, adavosertib (AZD1775). The latter is mediated through a synthetically lethal interaction between RRM2 suppression and MYC dysregulation that results in replication stress overload in Atm-/-nu-/-lymphoma cells. Validation in cell line models of human DLBCL confirmed the broad applicability of nucleotide depletion as a therapeutic strategy for MYC-driven DLBCL independent of ATM mutation status. Our findings extend current understanding of lymphomagenic mechanisms underpinning ATM loss and highlight nucleotide metabolism as a targetable therapeutic vulnerability in MYC-driven DLBCL.

Abstract LB081: Novel targeted oligonucleotide-based telomere disruptor for immunotherapy of diffuse large B-cell lymphoma

Abstract Telomerase (TERT) is an enzyme critical for carcinogenesis expressed in about 90% of human cancers, including aggressive diffuse large B-cell lymphoma (DLBCL). Targeting TERT proven difficult due to on-target toxicities to non-malignant hematopoietic stem cells and potentially to activated immune effector cells. To overcome these challenges, we developed novel TLR9+ cell-selective CpG-oligodeoxynucleotides (ODNs) to deliver telomere-damaging nucleoside analogue, 6-thio-2’-deoxy-guanosine (6tdG), into target B cell lymphoma cells in vitro and in vivo. Human and mouse TLR9+/TERT+ lymphoma cells rapidly internalized CpG(6tdG)-oligonucleotides through active endocytosis. 6tdG molecules were released from the 3’ end of the oligonucleotide into cytosol and cell nucleus. TERT-mediated 6tdG incorporation into telomeres, led to DNA damage and lymphoma cell death. In vitro, CpG(6tdG)-oligonucleotides showed potency in targeting variety of human DLBCL cells in nanomolar range without detectable toxicity to non-malignant TERT— cells or human TERT+ hematopoietic stem cells and activated T cells. Importantly, the repeated systemic administration of CpG(6tdG)-oligonucleotides was well-tolerated by humanized hCD34/NOG mice, without detectable decrease in the percentage of hematopoietic stem cells, myeloid cells or T cells although the numbers of B cells were partly reduced as expected. Intravenously injected CpG(6tdG)-oligonucleotides, but not 6tdG nucleoside, had potent and dose-dependent antitumor effects against xenotransplanted models of human GC- or ABC-subtypes of DLBCL, such as OCI-Ly18 or OCI-Ly3, respectively. Furthermore, we assessed CpG(6tdG)-oligonucleotide activity against aggressive, syngeneic TERT+ Eμ-myc/15A lymphoma in immunocompetent mice. CpG(6tdG)-oligonucleotide, but not the CpG-oligonucleotide alone, 6tdG alone or co-injection of thereof, was effective in triggering regression of established 15A tumors with long-term survival of the majority of mice. The effect of CpG(6tdG)-oligonucleotide correlated with the activation of tumor antigen-specific T cell-mediated antitumor immune responses. In contrast, when tested in immunodeficient mice, CpG(6tdG)-oligonucleotide induced significant but transient regression of 15A lymphoma. These results suggest that the oligonucleotide elicits two-pronged activity triggering direct lymphoma cell cytotoxicity and also immune-mediated antitumor effects. Overall, this cell-selective strategy could provide an effective and safer strategy against aggressive TERT+ DLBCL cells with potential to engage and support T cell-based antitumor immunity. Citation Format: Chunsong Yu, Yong Liang, Piotr Swiderski, Larry Kwak, Marcin Kortylewski. Novel targeted oligonucleotide-based telomere disruptor for immunotherapy of diffuse large B-cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB081.

Abstract 605: ABBV-101, a highly potent and selective clinical stage Bruton tyrosine kinase degrader, overcomes BTK mutation-induced resistance to BTK inhibitors

Abstract Bruton tyrosine kinase (BTK), a clinically validated target for various B-cell malignancies, plays a critical role in regulating cell growth, adhesion, and homing to lymphoid tissues that provide a microenvironment favorable to cancer cells. Despite the success of approved covalent BTK inhibitors in diseases such as CLL, most patients do not achieve complete response with monotherapy and eventually relapse, often via the emergence of the BTK-C481S mutation. Although second-generation reversible BTK inhibitors may temporarily overcome the C481S mutation, novel BTK mutations associated with resistance emerged in the clinic recently. Additionally, covalent BTK inhibitors have not shown sufficient differentiation from standard-of-care (SoC) in B-cell malignancies, such as diffuse large B cell lymphoma (DLBCL) to warrant approval to date. To address these unmet needs, a next-generation orally bioavailable BTK degrader ABBV-101 has been developed. Unlike BTK inhibitors that solely bind to and impede the catalytic domain of BTK, ABBV-101 eliminates the protein in a highly selective fashion. This degradation mechanism targets both the catalytic and scaffolding functions of BTK, and thus may enable deeper and more durable responses in patients with B-cell malignancies. Cellular activity of ABBV-101 was determined in a panel of DLBCL cell lines. We show that most non-germinal center B cell DLBCL (non-GCB-DLBCL) cell lines are sensitive to ABBV-101. To determine whether ABBV-101 could overcome BTK mutations-induced resistance, we engineered human DLBCL cell line TMD8 using CRISPR technology to express these BTK mutations and tested for sensitivity to ABBV-101 and BTK inhibitors. We show that ABBV-101 demonstrates similar potent activity against all BTK mutations associated with resistance to both covalent and reversible BTK inhibitors. The modulation of downstream pathway by ABBV-101 and how it differentiates from other BTK inhibitors will be presented. Further, ABBV-101 induces complete tumor regression in the BTK-C481S TMD8 DLBCL xenograft model. A spontaneous mouse CLL model carrying BTK-C481S mutation was developed through crossing BTK-C481S knock-in mice with the Emu-TCL1 transgenic mice in the C57BL/6 background. ABBV-101 completely inhibits BTK-C481S Emu-TCL1 CLL burden increase in the blood compartment and reduces CLL burden in the spleen and lymph nodes, whereas covalent BTK inhibitors show no activity. Finally, combination with a BCL-2 inhibitor enhances the efficacy of ABBV-101 in CLL and DLBCL models. Taken together, our results suggest that ABBV-101 has potent in vitro and in vivo efficacy. ABBV-101 is currently in phase 1 clinical trial for a variety of B-cell malignancies. ClinicalTrials.gov identifier: NCT05753501 Citation Format: Chin Pan, Jacob Riehm, Tarikere L. Gururaja, Haiyan Li, Henry Nguyen, Yongjiao Zhai, Xiaoping Xie, Rong-Xian Ding, Rebecca Matthew, Hana Y. Hoh, Zhaozhong J. Jia, Bo Liu, Cassandra P. Shu, Claudina A. Stevenson, Christine Will, Federico Innocenti, Wissam Assaily, Lloyd T. Lam, Alexey Rivkin. ABBV-101, a highly potent and selective clinical stage Bruton tyrosine kinase degrader, overcomes BTK mutation-induced resistance to BTK inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 605.

Kaempferol inhibits the proliferation and migration of Epstein-Barr virus-positive diffuse large B-cell lymphoma cells

Purpose: To assess the effect of kaempferol on the growth, apoptosis, and motility of Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) cells, and to elucidate its mechanism of action. &#x0D; Methods: Human DLBCL cells were used to generate EBV-positive (EBV +) cell line Pfeiffer. CCK-8, colony formation, flow cytometry (FCM), and immunoblot assays were employed to determine the effects of kaempferol on the growth and apoptosis of EBV + DLBCL cells. Cell motility was evaluated by Transwell and immunoblot assays. Immunoblot assay was further conducted to unravel the mechanism of action. &#x0D; Results: Kaempferol inhibited the growth of EBV + DLBCL cells. It also enhanced the apoptosis of EBV + DLBCL cells, but inhibited the motility of the cells. Furthermore, kaempferol inhibited PI3K/AKT axis, thereby suppressing DLBCL. &#x0D; Conclusion: Kaempferol inhibits the growth and motility of EBV + DLBCL cells via PI3K/AKT axis. It is therefore a potential drug for the treatment of DLBCL.

Fludarabine Enhances Radiosensitivity by Promoting Ferroptosis in B-Cell Lymphoma.

The objective of this study is to investigate the impact of fludarabine, a signal transducer and activator of transcription-1 (STAT1) inhibitor, on the radiosensitivity of B-cell lymphoma (BCL) and to explore the underlying mechanisms. Radiotherapy is one of the primary treatments for BCL, and STAT1 plays a critical role in the transcription of cell proliferation-related genes, which are associated with radiotherapy and ferroptosis. This study aims to determine whether fludarabine can enhance the radiosensitivity of BCL and to elucidate the molecular pathways involved. Various in vitro methodologies, including CCK-8 assays, clonogenic formation assays, immunohistochemistry, immunofluorescence, flow cytometry, qRT-PCR, and Western blot analyses, were employed in B-cell lymphoma cell models to thoroughly investigate the effects of fludarabine on radiosensitivity. Subsequently, the obtained results were further validated through invivo animal models and by examining human diffuse large B-cell lymphoma (DLBCL) cancer samples. Our findings demonstrate that the combination of fludarabine and irradiation synergistically inhibits cell viability and colony formation, while inducing apoptosis and ferroptosis in B-cell lymphoma cell lines Raji and Su-DHL-10. Moreover, fludarabine was found to enhance the ferroptosis induced by radiation, thereby synergistically impeding the growth of BCL. In vivo experiments confirmed these findings, revealing that the intraperitoneal injection of fludarabine significantly enhanced the inhibitory effects of radiation on Raji cell xenograft models, leading to an increased percentage of ferroptosis compared to models without fludarabine. Additionally, the administration of liproxstatin-1, a ferroptosis inhibitor, attenuated the inhibition of xenograft growth caused by the combination of fludarabine and irradiation. Furthermore, our analysis of clinical data revealed that increased co-expression of STAT1 and GPX4 is associated with poor overall survival in patients with diffuse large B-cell lymphoma. These results highlight the potential of fludarabine to enhance radiosensitivity and ferroptosis induction as a promising therapeutic strategy for BCL. Our results demonstrated that fludarabine promoted radiation-induced BCL death through the ferroptosis pathway. We have identified a previously unrecognized mechanism in the fludarabine and radiation combination, indicating that it is necessary to conduct prospective clinical trials to verify this new treatment regimen in BCL.

TNFAIP3 Overexpression Inhibits Diffuse Large B-Cell Lymphoma Progression by Promoting Autophagy through TLR4/MyD88/NF-κB Signaling Pathway.

Tumor necrosis factor alpha induced protein 3 (TNFAIP3) is reportedly to have significant implications for autophagy regulation in various cancers. The current study aimed to decipher the role and mechanism of TNFAIP3 in diffuse large B-cell lymphoma (DLBCL) by modulating autophagy. Information pertaining to the differential expression and prognostic role of TNFAIP3 in DLBCL was gleaned from the Gene Expression Omnibus (GEO) database. The TNFAIP3 expression levels in human DLBCL cells were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Cell counting kit-8 (CCK-8) and colony formation assays were employed to determine cell proliferation. Transwell assay and flow cytometry were applied to detect cell migration and apoptosis, respectively. Immunofluorescence and transmission electron microscope were used for the assessment of cell autophagy. The levels of apoptotic markers (caspase-3, cleaved-caspase-3, Bcl-2 Associated X (Bax), and B cell lymphoma-2 (Bcl-2)), autophagy indicators (the ratio of microtubule-associated proteins 1A/1B light chain 3 II and I (LC3II/LC3I), Sequestosome (p62)), and pathway proteins (toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), Transcription Factor NF-Kappa-B P65 Subunit (p65), and phosphorylated-p65 (p-p65)) were assessed via Western blotting. Immunohistochemistry was employed to detect Ki67 expression in tumor tissues. TNFAIP3 expression in DLBCL samples was downregulated, correlating with poor prognosis. TNFAIP3 expression was also downregulated in DLBCL cells. It was found that TNFAIP3 impeded cell proliferation and migration, and enhanced apoptosis of OCI-LY3 cells. Intervention with autophagy inhibitor 3-methyladenine (3-MA) markedly reversed apoptosis of OCI-LY3 cells induced by TNFAIP3. Besides, TNFAIP3 induced autophagy via modulating the TLR4/MyD88/nuclear factor kappa B (NF-κB) signaling pathway. In vivo experiments showed that TNFAIP3 expression in DLBCL was downregulated, and upregulation of TNFAIP3 could inhibit tumor growth. TNFAIP3 inhibits DLBCL progression by inducing TLR4/MyD88/NF-κB pathway-mediated autophagy.

Mouse models of diffuse large B cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is a genetically highly heterogeneous disease. Yet, to date, the vast majority of patients receive standardized frontline chemo-immune-therapy consisting of an anthracycline backbone. Using these regimens, approximately 65% of patients can be cured, whereas the remaining 35% of patients will face relapsed or refractory disease, which, even in the era of CAR-T cells, is difficult to treat. To systematically tackle this high medical need, it is important to design, generate and deploy suitable in vivo model systems that capture disease biology, heterogeneity and drug response. Recently published, large comprehensive genomic characterization studies, which defined molecular sub-groups of DLBCL, provide an ideal framework for the generation of autochthonous mouse models, as well as an ideal benchmark for cell line-derived or patient-derived mouse models of DLBCL. Here we discuss the current state of the art in the field of mouse modelling of human DLBCL, with a particular focus on disease biology and genetically defined molecular vulnerabilities, as well as potential targeting strategies.

Abbv-101, a Highly Potent and Selective Clinical Stage Bruton Tyrosine Kinase Degrader for the Treatment of B-Cell Malignancies

Bruton tyrosine kinase (BTK), a clinically validated target for various B-cell malignancies, plays a critical role in regulating cell growth, adhesion and homing to key lymphoid tissues that provide a microenvironment favorable to cancer cells. Despite the success of approved covalent BTK inhibitors in diseases such as CLL, most patients do not achieve complete response with monotherapy and eventually relapse, often via the emergence of the BTK-C481S mutation. Additionally, covalent BTK inhibitors have not shown sufficient differentiation from standard-of-care (SoC) in B-cell malignancies such as diffuse large B cell lymphoma (DLBCL) to warrant approval to date. To address these unmet needs, a next-generation orally bioavailable BTK degrader ABBV-101 has been developed. Unlike BTK inhibitors that solely bind to and impede the catalytic domain of BTK, ABBV-101 eliminates the protein in a highly selective fashion. This degradation mechanism targets both the catalytic and scaffolding functions of BTK, and thus may enable deeper and more durable responses in patients with B-cell malignancies. In preclinical studies, the BTK degrader ABBV-101 has shown potent in vitro and in vivo efficacy in BCR pathway-dependent leukemia/lymphoma models, including covalent BTK inhibitor resistant BTK-C481S systemic mouse CLL and human DLBCL models. ABBV-101 degrades BTK-WT and BTK-C481S with similar sub-nanomolar potency in the human DLBCL cell line TMD8 which translates to potent cellular growth inhibition. In addition to the BTK-C481S mutation, ABBV-101 demonstrates similar potent activity against novel BTK mutations associated with resistance to reversible BTK inhibitors in the clinic, an emerging unmet need. ABBV-101 induces complete tumor regression in the BTK-C481S TMD8 DLBCL xenograft model. A spontaneous mouse CLL model carrying BTK-C481S mutation was developed through crossing BTK-C481S knock-in mice with the Emu-TCL1 transgenic mice in the C57BL/6 background. ABBV-101 completely inhibits BTK-C481S Emu-TCL1 CLL burden increase in the blood compartment and reduces CLL burden in the spleen and lymph nodes, whereas covalent BTK inhibitors show no activity. Further, ABBV-101 induces complete tumor regressions in multiple non-GCB DLBCL PDX models, demonstrating deeper and more durable response than covalent and reversible inhibitors. Combination with a BCL-2 inhibitor enhances the efficacy of ABBV-101 in CLL and DLBCL models. Kinome and global proteomics profiling showed ABBV-101 to be highly selective, a designed feature that may enable favorable tolerability in patients. ABBV-101 is currently in phase 1 clinical trial for a variety of B-cell malignancies. ClinicalTrials.gov identifier: NCT05753501

Qpctl Inhibition, By Targeting the Inflammatory Tumor Microenvironment, Constitutes a Novel Therapeutic Approach for Diffuse Large B-Cell Lymphoma

We have previously described that diffuse large B-cell lymphomas (DLBCL) harboring an inflammatory and immunosuppressive microenvironment (i.e., IN-LME) carry independent poor prognosis while proof-of-principle experiments modifying the composition of the LME were sufficient to induce lymphoma regression in mice models ( Kotlov, Cancer Discovery 2021). However, identification of pharmaceutical approaches that by modifying the LME will induce an anti-lymphoma effect while being suitable for short-term human translation remains challenging. The IN-LME is characterized by the presence of pro-inflammatory and immunosuppressive chemokines and cytokines that frequently undergo post-translational modifications. QPCTL (glutaminyl-peptide cyclotransferase-like) is an intracellular enzyme that mediates a N-terminal pyroglutamylation of CD47 and several chemokines, including CCL2 and CCL7, ultimately resulting in their sustained expression and/or secretion. SC-2882 is a first-in-class specific QPCTL inhibitor that induces secondary proteolytic degradation of the monocyte chemoattractants CCL2 and CCL7 ( da Silva, Nature Immunology 2022) and inactivation of the “do-not-eat-me” signal CD47 ( LogtenbergNature Medicine 2019). In a dataset of 470 DLBCL patients we found that the expression of QPCTL correlates negatively with overall survival and progression free survival (0.019 and &amp;lt;0.001, respectively). To determine whether QPCTL could be a potential target in DLBCL, we investigated its expression along with its targets CCL2, CCL7 and CD47 in additional 216 DLBCL cases categorized by LME. We found that while QPCTL and CD47 are expressed at similar levels in all DLBCL cases regardless their COO class and LME category, CCL2 was highly expressed in DLBCL harboring a IN-LME (p &amp;lt;0.05 vs. other LME categories), that also correlate with higher presence of tumor-associated macrophages (TAMs) and exhausted CD8+PD1 HIGH T cells (p &amp;lt;0.01 and p&amp;lt;0.001, vs. other LME categories, respectively). CCL7 was not expressed at detectable levels in majority of LMEs in DLBCL. In preclinical models, murine and human DLBCL cell lines expressed baseline QPCTL and CD47 while CCL2 and CCL7 expression (qPCR) and secretion (ELISA) increased at higher levels upon culturing these cells for 24 h embedded in splenic extracellular matrix 3D cultures. Exposure of a panel of 3 murine and 5 human DLBCL cells to increasing concentrations of SC-2882 (vs. vehicle) for up to 72 h and up to a 10 micromolar dose had no noticeable decrease in cell viability or proliferation. However, SC-2882 (vs. vehicle) at nanomolar concentrations increased anti-Cd20-dependent lymphoma cell phagocytosis by in vitro differentiated macrophages (from splenic monocytes in mice and THP1 cells in humans) in 3D co-cultures (p &amp;lt; 0.05, for all conditions). To further test the anti-lymphoma effect of SC-2882 we used a murine GCB-DLBCL model by implanting GEMM-derived aggressive Ezh2 mutant (EZH2 Y646equivalent) + BCL2 amplified lymphoma cells in the spleen of immunocompetent C57BL/mice (n=14). After implantation, mice were randomized to receive SC-2882 by oral gavage (n=7) or vehicle (n=14) for 14 days. Tumor burden was followed by luciferase imaging (Caliper), and spleens were analyzed at sacrifice by multiparametric imaging, flow-cytometry, and spatial transcriptomics. Oral SC-2882 (vs. vehicle) induced a significant decrease in tumor growth (p=0.0079, Figure 1) without evidence of systemic toxicity by body weight, blood cell count and chemistry panel. Analysis of the LME in remnant splenic tumors showed in SC-2882 (vs. vehicle) treated mice a significant decrease in lymphoma cells and Ki67+ cells (p&amp;lt;0.001) as well as F480+ TAMs (p&amp;lt;0.01) while there was an increase of CD3+ T cell infiltration (p&amp;lt;0.001). We also found a decrease in Cd4+Foxp3+ Tregs and increase in Cd8+Gzb+ cells in SC-2882 treated mice by flow-cytometry. These changes mirrored the findings in the spatial transcriptomics. Additional analysis of LME cell subpopulations by SC-RNA-seq is ongoing. Overall, these data indicate that QPCTL is a potential target in DLBCL, and that QPCTL inhibition exhibits potent anti-lymphoma effects primarily by targeting the IN-LME.

Cd70 Deficiency Impairs CD4 + and CD8 + T-Cell Immune Surveillance in Bcl6-Driven Diffuse Large B-Cell Lymphomas

Anti-tumor immune responses to lymphoid malignancies are modulated by co-stimulatory and co-inhibitory pathways. Our group previously characterized the recurrent genetic alterations in primary diffuse large B-cell lymphomas (DLBCL) and identified frequent inactivating mutations or copy loss of the CD70 co-stimulatory ligand in these tumors. CD70 co-stimulation of CD27 + T cells induces antigen-dependent T-cell expansion and immune surveillance of normal and malignant B cells. Given the frequent combination of CD70 and BCL6 alterations in our human DLBCL series, we investigated the consequences of CD70deficiency ( Cd70 -/-) in a murine model of BCL6-driven lymphomagenesis ( Bcl6 tg/+). Cd70 -/-; Bcl6 tg/+ animals developed predominantly splenic DLBCLs with earlier onset and increased penetrance when compared to Bcl6 tg/+ mice (p&amp;lt;.01). Hence, to elucidate potential differences in T-cell mediated anti-tumor responses in Cd70 -/-; Bcl6 tg/+ versus Bcl6 tg/+ mice (and wild-type (WT) and Cd70 -/- animals) and to characterize the concurrent processes of B-cell transformation and immune evasion over time, we performed single-cell RNA sequencing of splenic cell suspensions from animals euthanized for symptoms and additional asymptomatic mice at pre-determined timepoints (6, 14 and 18 months). We applied unsupervised clustering and defined the major B- and T-cell types based on canonical lineage markers. Additionally, we reconstructed the splenic T-cell receptor (TCR) and B-cell receptor (BCR) sequences with the TRUST4 algorithm to assess their diversity and clonal expansion. TRUST4 analyses revealed clonally expanded B cells that were primarily found in specific clusters. These clusters also had an increased number of aberrant cells identified with an orthogonal approach that detects copy number alterations, InferCNV. Certain of these clusters were more abundant in aged asymptomatic Bcl6 tg/+ and Cd70 -/-; Bcl6 tg/+ animals than in symptomatic mice. Aberrant cells in these clusters had a memory-like IgM + phenotype ( Nt5e, Zeb2, Cd38, Cd44, Itgb1) and included two discrete populations: 1) previously described age-associated/autoimmune-like cells ( Tbx21, Cd11c, Cd11b) and 2) newly appreciated atypical memory cells . Additional clusters that were predominantly found in symptomatic animals included aberrant cells with increased expression of cycling genes and downregulation of lineage-defining markers and MHC II (p&amp;lt;.001). We interpret the aberrant memory-like B-cells in asymptomatic Cd70 -/-; Bcl6 tg/+ and Bcl6 tg/+ animals to be precursors of the ones detected in symptomatic mice. Importantly, malignant clonal expansion and splenomegaly occurred at earlier timepoints and to a greater extent in Cd70 -/-; Bcl6 tg/+ than Bcl6 tg/+ mice (p&amp;lt;.01). To further characterize potential anti-tumor immune responses, we examined splenic CD8 + and CD4 + T-cell subsets in tumor-bearing cohorts ( Bcl6 tg/+ and Cd70 -/-; Bcl6 tg/+) and control animals (WT and Cd70 -/-). In the tumor-bearing cohorts, we detected selective expansion of CD8 + cytotoxic T cells (CTLs) with a spectrum of activation and exhaustion markers. CD8 + CTL expansion was significantly greater in Bcl6 tg/+ mice than Cd70 -/-; Bcl6 tg/+ animals. We also identified selective expansion of a major CD4 + CTL compartment ( GzmB, Prf1, Eomes) in the tumor-bearing cohorts that persisted significantly longer in Bcl6 tg/+ than Cd70 -/-; Bcl6 tg/+ mice. In the tumor-bearing cohorts at 18 months, there was significantly greater clonal expansion of CD4 + CTLs, in comparison to CD8 + CTLs, highlighting the likely importance of this understudied cytotoxic CD4 + T-cell subset. In this regard, the downregulation of MHC II on the malignant B cells of symptomatic mice likely favored CD4 + CTL immune escape and accelerated the development of overt lymphoma. Taken together, our data indicate that genetic perturbation of CD70/CD27 co-stimulation limits the development of an effective T-cell mediated immune response to Bcl6 tg/+-driven DLBCL and highlights the unanticipated role of CD4 + CTLs and MHC II down-regulation in the attempted development and subsequent loss of an anti-tumor immune response. Additionally, we identified previously unappreciated precursor populations of murine DLBCL that warrant further investigation in human tumors.

High Level of IL-16 Secreted By Non-GCB DLBCL Facilitates Tumor Growth Though the Tumor-Promoting and Immunosuppressive Tumor Microenvironment

Introduction: Diffuse Large B-Cell Lymphoma (DLBCL) is a highly heterogeneous non-Hodgkin's lymphoma. Based on cell origin, DLBCL is classified into two main molecular subtypes: the germinal center B-cell-like (GCB) subtype and the activated B-cell-like (ABC) subtype. ABC subtype is more aggressive and associated with a worse prognosis than GCB subtype. Previous studies have shown that cytokines play an important role in the growth of ABC subtypes, and IL-16 was supposed to be highly expressed in ABC-DLBCL, however it has not been explored in depth in DLBCL. In this study, we broadly assessed the expression and role of IL-16 on DLBCL. Method: Serum and tissues samples from patients with DLBCL and whole blood from healthy donors were collected. The characterization of protein expression, mRNA expression, and levels of cytokines in cells and tissues was detected by Western blotting, IHC/IHF, PCR, ELISA, RNA-seq, and Flow cytometry. Cells experiments such as cell proliferation, cell apoptosis, cell cycle, cell migration, and ADPC were detected by CCK-8, Flow cytometry, and Transwells. Gene knockdown or overexpression was conducted by lentiviruses and then verified by Western blotting and ELISA. We established subcutaneous tumors (human DLBCL cells and murine DLBCL cells) in BALB/c mice, BALC/c nude mice, and NOD SCID mice for the tumor size or the therapeutic evaluation. Results: First, we found that IL-16, secreted by the cleavage of active caspase-3 from the lymphoma cells under tumor burden, was highly expressed in ABC-DLBCL compared to GCB-DLBCL. The serum IL-16 levels were positively correlated with unfavorable prognosis in DLBCL patients. The dynamic change of serum IL-16 levels accurately predicted the treatment response in patients with DLBCL who received R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone) or anti-CD19 Chimeric Antigen Receptor (CAR) T cells. Interestingly, bioactive IL-16 showed rare effect on DLBCL cells in vitro, but significantly promoted their growth in vivo. Mechanically, tumor-derived bioactive IL-16 promoted the migration of monocytes via CD4+ receptor, thereby inducing the enrichment of monocytes-derived tumor-associated macrophages in the tumor microenvironment (TME) of DLBCL, which accelerated the tumor growth primarily by expressing cytokines such as IL-6, inducing angiogenesis, and exerting immunosuppressive effects through the expression of cytokines like IL-10; thus, conferring growth advantage to the ABC- DLBCL. To translate the findings into clinical application, we design a novel treatment strategy to overcome the poor outcomes in ABC-DLBCL patients with high IL-16 expression by combination of high-dose cyclophosphamide (CTX) and the bispecific antibody targeting CD20 and CD47 (IMM0306). IMM0306 effectively reversed the tumor-promoting effects of macrophages in subsets of ABC-DLBCL, while CTX induced IL-16 and increased the infiltration of macrophages in the TME. The increasing effector cells/tumor cells ratio further improved the antitumor effect of IMM0306. The combination of high-dose CTX and IMM0306 was confirmed to significantly inhibit the growth of ABC-DLBCL with high IL-16 expression. A clinical trial is being designed to evaluate the potential for clinical applications. Conclusion: In conclusion, this study provides insight into the expression and role of IL-16 in DLBCL. IL-16 is proposed to be highly expressed in ABC-DLBCL, and serum IL-16 indicate the tumor burden, treatment response, and clinical prognosis of DLBCL patients. IL-16 may be a key driver of the TME of DLBCL, which can confer growth advantage to the ABC-DLBCL. Our data provides a theoretical basis for future clinical treatment. A novel treatment regimen (IMM0306 and CTX) could attenuate the pro-oncogenic roles of IL-16 to prevent ABC-DLBCL progression.

ONO-7018, a First-in-Class MALT1 Inhibitor, Provides Novel Therapeutic Strategies for B Cell Malignancies: Overcoming BTK Inhibitor Acquired Resistance and Enhancing the Antitumor Effect of BTK Inhibitors

Introduction: B cell receptor (BCR) signaling plays a crucial role in promoting survival and growth in B cell malignancies, and several compounds targeting the signaling pathways have been approved. Bruton's tyrosine kinase (BTK) is a key molecule in BCR signaling pathways and BTK inhibitors are one of the essential treatment options for chronic lymphocytic leukemia (CLL) and certain subtypes of B cell Non-Hodgkin Lymphoma. However, there are issues that acquired resistance mutations in the BTK kinase domain and gain of function mutation of its downstream molecules, which lead to BTK inhibitor resistance and limit its efficacy. For example, BTK C481S mutation is well known as a resistant mutation to covalent BTK inhibitors and several mutations of BTK (such as T474I and L528W mutation) have recently been reported in relapsed or refractory CLL patients with acquired resistance to pirtobrutinib, a non-covalent BTK inhibitor. In addition, there are unmet medical needs to improve the duration of response of current standard therapies including BTK inhibitors for B cell malignancies. Therefore, therapeutic strategies to overcome the BTK inhibitor resistance and novel combination therapies to enhance the efficacy of BTK inhibitors are required. Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is known as a key growth and survival regulator in BCR signaling and an emerging therapeutic target. ONO-7018 (formerly known as CTX-177), a potent and selective MALT1 inhibitor, demonstrated preclinical efficacy in several lymphoma models. Aim: Firstly, to explore the potential of ONO-7018 to overcome BTK inhibitor acquired resistance, we tested the antitumor effects of ONO-7018 on cell lines harboring BTK inhibitor-resistant mutations. Secondly, we examined the combination antitumor efficacy of ONO-7018 and tirabrutinib, a second generation BTK inhibitor in vitro and in vivo. Methods: Diffuse large B-cell lymphoma (DLBCL) cell lines harboring BTK inhibitor-resistant mutations (BTK T474I, C481S, or L528: PLCG2 R665W) were generated by continuous passage with BTK inhibitor or CRISPR-Cas9 gene editing followed by single cell cloning. In in vivo study, human DLBCL cell line, TMD8 cells were subcutaneously implanted in immune deficient mice. ONO-7018 and tirabrutinib were orally administered to the mice twice a day. Results: Anti-proliferative activities of ONO-7018 on these BTK inhibitor resistant cell lines were evaluated in vitro. ONO-7018 inhibited the proliferation of these cells with comparable IC 50 values to the parent cell line. Anti-proliferative activities of ONO-7018 alone or in combination with tirabrutinib on DLBCL and mantle cell lymphoma (MCL) cell lines were evaluated in vitro. ONO-7018 exhibited synergistic effects with tirabrutinib in both DLBCL and MCL cell lines. In addition, combination treatment of ONO-7018 with tirabrutinib strongly inhibited the expression of interferon regulatory factor 4, which is a downstream signal molecule in BCR signaling pathways, compared to their single treatment. We then evaluated the antitumor effects of ONO-7018 in combination with tirabrutinib in the xenograft model. Combination treatment of ONO-7018 with tirabrutinib showed dramatic antitumor effect with tumor regression. These results suggest that ONO-7018 could demonstrate antitumor effect on patients with B cell malignancies harboring BTK inhibitor acquired resistant mutations and synergistic antitumor effect with BTK inhibitors in clinic. Conclusion: ONO-7018 would provide novel therapeutic strategies to overcome the BTK inhibitor acquired resistance and enhance the antitumor effect of BTK inhibitors in clinic. Phase 1 study of ONO-7018 (NCT05515406) is currently ongoing.

EZH2 Inhibitors Enhance CART Cell Quality, Efficacy, In Vivo Homing, Tumor Cell Binding and Killing of Fully Syngeneic Primary B Cell Lymphomas, As Well As Reprogramming Lymphoma Cells to a Highly Immunogenic and T Cell Adherent Phenotype

Although having efficacy in a subset of diffuse large B cell lymphoma (DLBCL) patients, cellular immunotherapies are currently administered without guidance as to whether the underlying biology or immunology are conducive to durable response. Moreover, mechanisms explaining CART resistance in DLBCLs remain largely unknown. One critical missing link to address these unmet needs are syngeneic animal models precisely reflecting the genetics and immunology of human DLBCLs. To overcome these hurdles, we developed a suite of genetically engineered mouse models (GEMM) faithfully recapitulating different types of DLBCL. A retrospective study showed that C3/EZB DLBCLs, featuring EZH2 mutations and BCL2 translocation, experienced inferior outcomes after CART therapy. We reported that Ezh2 mutations cause aberrant repression of genes required for productive immune synapses with T cells. We hypothesized that this phenotype limits CART cell activity in vivo, and that EZH2 inhibitors could overcome CART resistance. We generated EZB GEMMs with conditional expression of Ezh2 Y641F and BCL2 in germinal center (GC) B cells. These mice developed T cell depleted lymphomas, histologically similar to human C3/EZB DLBCLs. We generated several EZB cell lines from these mice, which recapitulated the epigenetic, transcriptional, histological, and immune microenvironment of EZB DLBCLs in humans when engrafted in immunocompetent recipients. Strikingly, treating EZB cells with EZH2 inhibitor tazemetostat (taz) ex vivo reprogrammed them to re-express the full spectrum of T cell engagement genes such as ICOSL, ITGB7, 4-1BBL, and OX40L and rendered them highly immunogenic. For example, mixing endogenous T cells with taz pre-treated EZB cells yielded markedly enhanced killing (p&amp;lt;0.001). Taz pre-treated EZB cells failed to engraft in syngeneic mice due to immunological rejection, but caused fatal DLBCL in Rag1-/- mice. EZB cell lines did not undergo proliferation arrest after taz ex vivo, but showed a significant reduction in tumor burden (p&amp;lt;0.05) when treated in vivo, along with a 3-fold increase in tumor CD4 and CD8 cells (p&amp;lt;0.05), and 50% reduction in Tregs (p&amp;lt;0.01). Taz also increased the proportion of naïve/memory CD8 and reduced effector CD8 cells. EZH2 inhibitors therefore mediate their effects at least in part through immunological mechanisms. We next examined whether taz had any deleterious effect on CART cells. Pre-treating donor mice with taz prior to harvesting T cells yielded significant increase in memory CD8 CART cells after transduction (p&amp;lt;0.05). Taz pre-treated CART cells displayed superior killing of EZB cells (p&amp;lt;0.001) and proliferative capacity ex vivo (p&amp;lt;0.001). Infusing taz pre-treated CART cells in EZB mice resulted in significantly reduced tumor burden in vivo (p&amp;lt;0.001) and reduction in PD1+CD38+ exhausted CD8 CART cells (p&amp;lt;0.001). On the other hand, pre-treatment of EZB cells (but not CART cells) with taz ex vivo enhanced CART cell killing by 3-fold (p&amp;lt;0.001). Administering CART cells in vivo in EZB mice after taz treatment significantly prolonged their survival (100% vs 30%, p&amp;lt;0.01) and was associated with significant reduction in tumor burden assessed by IVIS and post-mortem examination. Therefore, EZH2 inhibition enhances CART cell activity through direct effects on CART cells, in addition to making EZB immunogenic. Finally, to directly demonstrate the functional consequence of rendering EZB lymphomas immunogenic on CART performance in vivo, we performed intravital 2-photon imaging of popliteal lymph nodes using dTomato labeled CART cells and GFP+ EZB lymphomas. Remarkably, pre-treatment of EZB cells with taz, doubled the recruitment of CART cells into lymphomas (p&amp;lt;0.001) and significantly enhanced the CART to EZB lymphoma cell surface engagement index (strength and duration of binding, p&amp;lt;0.001). This was associated with increased killing, and CART-engaged lymphoma cells were observed to be ingested/engulfed or phagocyted by tumor resident macrophages. Collectively, EZH2 inhibitors yield a potent boost to CART mediated anti-lymphoma effects by enhancing CART cell functions and B cell immunogenicity, which would likely yield a significant clinical benefit for these patients where CART cells are less active. These results prompted us to initiate a clinical trial evaluating the safety and efficacy of this combination in B cell lymphomas (NCT05934838).

A Combination of CPI-0610 and SAHA Induces Apoptosis through STAT3 and p38 Signalling Pathways in Diffuse Large B-cell Lymphoma Cells.

Although immunotherapies have greatly improved diffuse large B-cell lymphoma (DLBCL) prognosis, a proportion of patients remain to be relapsed or refractory. Therefore, the identification of novel therapeutic targets and drugs is urgently required. Inhibition of the bromodomain and extra-terminal (BET) proteins has been a promising therapeutic strategy for various haematologic cancers. CPI-0610 is a potent and selective BET inhibitor. The effects of CPI-0610 in DLBCL cells have not been reported yet. The aim of this study was to assess the effects of CPI-0610 in DLBCL and its underlying mechanisms. DLBCL cells were treated with CPI-0610, followed by measuring cell viability, cell cycle, apoptosis, autophagy, and specific cell signaling pathways. Moreover, immunodeficient mice were engrafted with SUDHL2 cells and then treated with CPI-0610 for analysis of tumor burden. We also analyzed the synergistic effect of CPI-0610 with histone deacetylase inhibitor suberoylanilide hydroxamic acid. The present study demonstrated that CPI-0610 displayed cell cytotoxicity by arresting the G1 cell cycle and inducing endogenous and exogenous apoptotic pathways. Additionally, CPI-0610 decreased BRD4 and c-Myc expressions and affected MAPK, JAK/STAT, and AKT signalling pathways in human DLBCL cells. An in vivo experiment exhibited that CPI-0610 decreased the primary tumour growth of the DLBCL xenograft model. Furthermore, the use of CPI-0610 in combination with suberoylanilide hydroxamic acid exhibited a specific synergistic effect in inducing apoptosis through the regulation of STAT3 and p38. Targeting BET may be an effective therapeutic strategy and potentiated by a combination with histone deacetylase inhibition in DLBCL.

Targeted Polymersome Delivery of a Stapled Peptide for Drugging the Tumor Protein p53:BCL-2-Family Axis in Diffuse Large B-Cell Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) remains a formidable diagnosis in need of new treatment paradigms. In this work, we elucidated an opportunity for therapeutic synergy in DLBCL by reactivating tumor protein p53 with a stapled peptide, ATSP-7041, thereby priming cells for apoptosis and enhancing their sensitivity to BCL-2 family modulation with a BH3-mimetic, ABT-263 (navitoclax). While this combination was highly effective at activating apoptosis in DLBCL in vitro, it was highly toxic in vivo, resulting in a prohibitively narrow therapeutic window. We, therefore, developed a targeted nanomedicine delivery platform to maintain the therapeutic potency of this combination while minimizing its toxicity via packaging and targeted delivery of a stapled peptide. We developed a CD19-targeted polymersome using block copolymers of poly(ethylene glycol) disulfide linked to poly(propylene sulfide) (PEG-SS-PPS) for ATSP-7041 delivery into DLBCL cells. Intracellular delivery was optimized in vitro and validated in vivo by using an aggressive human DLBCL xenograft model. Targeted delivery of ATSP-7041 unlocked the ability to systemically cotreat with ABT-263, resulting in delayed tumor growth, prolonged survival, and no overt toxicity. This work demonstrates a proof-of-concept for antigen-specific targeting of polymersome nanomedicines, targeted delivery of a stapled peptide in vivo, and synergistic dual intrinsic apoptotic therapy against DLBCL via direct p53 reactivation and BCL-2 family modulation.

Baseline tumor gene expression signatures correlate with chemoimmunotherapy treatment responsiveness in canine B cell lymphoma.

Pet dogs develop spontaneous diffuse large B cell lymphoma (DLBCL), and veterinary clinical trials have been employed to treat canine DLBCL and to inform clinical trials for their human companions. A challenge that remains is selection of treatment to improve outcomes. The dogs in this study were part of a larger clinical trial evaluating the use of combinations of doxorubicin chemotherapy, anti-CD20 monoclonal antibody, and one of three small molecule inhibitors: KPT-9274, TAK-981, or RV1001. We hypothesized that significant differential expression of genes (DEGs) in the tumors at baseline could help predict which dogs would respond better to each treatment based on the molecular pathways targeted by each drug. To this end, we evaluated gene expression in lymph node aspirates from 18 trial dogs using the NanoString nCounter Canine Immuno-oncology (IO) Panel. We defined good responders as those who relapsed after 90 days, and poor responders as those who relapsed prior to 90 days. We analyzed all dogs at baseline and compared poor responders to good responders, and found increased CCND3 correlated with poor prognosis and increased CD36 correlated with good prognosis, as is observed in humans. There was minimal DEG overlap between treatment arms, prompting separate analyses for each treatment cohort. Increased CREBBP and CDKN1A for KPT-9274, increased TLR3 for TAK-981, and increased PI3Kδ, AKT3, and PTEN, and decreased NRAS for RV1001 were associated with better prognoses. Trends for selected candidate biomarker genes were confirmed via qPCR. Our findings emphasize the heterogeneity in DLBCL, similarities and differences between canine and human DLBCL, and ultimately identify biomarkers that may help guide the choice of chemoimmunotherapy treatment in dogs.