Harnessing the cytotoxic granule exocytosis to augment the efficacy of T-cell-engaging bispecific antibody therapy

T-cell-engaging bispecific antibody (T-BsAb, also known as BiTE) therapy has emerged as a powerful therapeutic modality against multiple myeloma. Given that T-BsAb therapy redirects endogenous T cells to eliminate tumor cells, reinvigorating dysfunctional T cells may be a potential approach to improve the efficacy of T-BsAb. While various immunostimulatory cytokines can potentiate effector T-cell functions, the optimal cytokine treatment for T-BsAb therapy is yet to be established, partly due to a concern of cytokine release syndrome driven by aberrant interferon (IFN)-γ production. Here, we functionally screen immunostimulatory cytokines to determine an ideal combination partner for T-BsAb therapy. This approach reveals interleukin (IL)-21 as a potential immunostimulatory cytokine with the ability to augment T-BsAb-mediated release of granzyme B and perforin, without increasing IFN-γ release. Transcriptome profiling and functional characterization strongly support that IL-21 selectively targets the cytotoxic granule exocytosis pathway, but not pro-inflammatory responses. Notably, IL-21 modulates multiple steps of cytotoxic effector functions including upregulation of co-activating CD226 receptor, increasing cytotoxic granules, and promoting cytotoxic granule delivery at the immunological synapse. Indeed, T-BsAb-mediated myeloma killing is cytotoxic granule-dependent, and IL-21 priming significantly augments cytotoxic activities. Furthermore, in vivo IL-21 treatment induces cytotoxic effector reprogramming in bone marrow T cells, showing synergistic anti-myeloma effects in combination with T-BsAb therapy. Together, harnessing the cytotoxic granule exocytosis pathway by IL-21 may be a potential approach to achieve better responses by T-BsAb therapy.

Systemic diffuse large B-cell lymphoma involving the central nervous system have high rates of defective antigen presentation and immune surveillance

Not available.

Regulatory T cells hamper the efficacy of T-cell-engaging bispecific antibody therapy

T-cell-engaging bispecific antibodies (T-BsAb) have produced impressive clinical responses in patients with relapsed/refractory B-cell malignancies, although treatment failure remains a major clinical challenge. Growing evidence suggests that a complex interplay between immune cells and tumor cells is implicated in the mechanism of action and therefore, understanding immune regulatory mechanisms might provide a clue for how to improve the efficacy of T-BsAb therapy. Here, we investigated the functional impact of regulatory T (Treg) cells on anti-tumor immunity elicited by T-BsAb therapy. In a preclinical model of myeloma, the activation and expansion of Treg cells in the bone marrow were observed in response to anti-B-cell maturation antigen (BCMA) T-BsAb therapy. T-BsAb triggered the generation of induced Treg cells from human conventional CD4 cells after co-culture with tumor cells. Moreover, T-BsAb directly activated freshly isolated circulating Treg cells, leading to the production of interleukin-10 and inhibition of T-BsAb-mediated CD8 T-cell responses. The activation of Treg cells was also seen in bone marrow samples from myeloma patients after ex vivo treatment with T-BsAb, further supporting that T-BsAb have an impact on Treg homeostasis. Importantly, transient ablation of Treg cells in combination with T-BsAb therapy dramatically improved effector lymphocyte activities and disease control in the preclinical myeloma model, leading to prolonged survival. Together, this information suggests that therapy-induced activation of Treg cells critically regulates anti-tumor immunity elicited by T-BsAb therapy, with important implications for improving the efficacy of such treatment.

Epstein-Barr virus-associated lymphomas decoded

Epstein-Barr virus (EBV)-associated lymphomas cover a range of histological B- and T-cell non-Hodgkin and Hodgkin lymphoma subtypes. The role of EBV on B-cell malignant pathogenesis and its impact on the tumour microenvironment are intriguing but incompletely understood. Both the International Consensus Classification (ICC) and 5th Edition of the World Health Organization (WHO-HAEM5) proposals give prominence to the distinct clinical, prognostic, genetic and tumour microenvironmental features of EBV in lymphoproliferative disorders. There have been major advances in our biological understanding, in how to harness features of EBV and its host immune response for targeted therapy, and in using EBV as a method to monitor disease response. In this article, we showcase the latest developments and how they may be integrated to stimulate new and innovative approaches for further lines of investigation and therapy.

Expanding the bacterial origins of nodular lymphocyte-predominant Hodgkin lymphoma

Not available.

Genome-wide transcription factor-binding maps reveal cell-specific changes in the regulatory architecture of human HSPCs

Hematopoietic stem and progenitor cells (HSPCs) rely on a complex interplay among transcription factors (TFs) to regulate differentiation into mature blood cells. A heptad of TFs (FLI1, ERG, GATA2, RUNX1, TAL1, LYL1, LMO2) bind regulatory elements in bulk CD34+ HSPCs. However, whether specific heptad-TF combinations have distinct roles in regulating hematopoietic differentiation remains unknown. We mapped genome-wide chromatin contacts (HiC, H3K27ac, HiChIP), chromatin modifications (H3K4me3, H3K27ac, H3K27me3) and 10 TF binding profiles (heptad, PU.1, CTCF, STAG2) in HSPC subsets (stem/multipotent progenitors plus common myeloid, granulocyte macrophage, and megakaryocyte erythrocyte progenitors) and found TF occupancy and enhancer-promoter interactions varied significantly across cell types and were associated with cell-type-specific gene expression. Distinct regulatory elements were enriched with specific heptad-TF combinations, including stem-cell-specific elements with ERG, and myeloid- and erythroid-specific elements with combinations of FLI1, RUNX1, GATA2, TAL1, LYL1, and LMO2. Furthermore, heptad-occupied regions in HSPCs were subsequently bound by lineage-defining TFs, including PU.1 and GATA1, suggesting that heptad factors may prime regulatory elements for use in mature cell types. We also found that enhancers with cell-type-specific heptad occupancy shared a common grammar with respect to TF binding motifs, suggesting that combinatorial binding of TF complexes was at least partially regulated by features encoded in DNA sequence motifs. Taken together, this study comprehensively characterizes the gene regulatory landscape in rare subpopulations of human HSPCs. The accompanying data sets should serve as a valuable resource for understanding adult hematopoiesis and a framework for analyzing aberrant regulatory networks in leukemic cells.

A coordinated strategy for a simple, pragmatic approach to the early identification of the ultra-high-risk patient with diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most frequent aggressive lymphoma seen in clinical practice. Despite huge strides in understanding its biology, front-line therapy has remained unchanged for decades. Roughly one-third of patients have primary refractory or relapse following the end of conventional first-line therapy. The outcome of patients with primary refractory disease and those with early relapse (defined as relapse less than 1 year from the end of therapy) is markedly inferior to those with later relapse and is exemplified by dismal overall survival. In this article, the authors term patients with features that identify them as being at particularly high-risk for either primary refractory disease or early relapse, as 'ultra-high-risk'. As new treatment options become established (e.g. bispecific T-cell engagers, chimeric antigen receptor 'CAR' T-cells and antibody-drug conjugates), it is likely that there will be a push to incorporate some of these agents into the first-line setting for patients identified as ultra-high-risk. In this review, the authors outline advances in positron emission tomography, widely available laboratory assays and clinical prognosticators, which can detect a high proportion of patients with ultra-high-risk disease. Since these approaches are pragmatic and able to be adopted widely, they could be incorporated into routine clinical practice.

EBV-positive PCNSL in older patients: incidence, characteristics, tumor pathology, and outcomes across a large multicenter cohort

The objective of this multicenter retrospective study was to examine the incidence, patient characteristics, pathology, and outcomes associated with Epstein-Barr virus (EBV)-related CNS lymphoma (CNSL) in older patients. Among 309 CNSL patients aged ≥60, 11.7% had EBV + tumors of which 72.2% were solid organ transplant (SOT)-related post-transplant lymphoproliferative disorders (PTLD). Younger age, SOT or autoimmune disease, and immunosuppressive treatment correlated highly with EBV-positivity. EBV + tumors were associated with absent C-MYC and BCL6 expression. EBV + PTLD was more likely to be associated with the absence of CD5 expression. EBV + non-PTLD had better median OS (not reached) compared to EBV + PTLD (10.8 months) and EBV-negative patients (43 months). Multivariable Cox regression analysis showed that age, performance status, and PTLD were negative predictors of OS. EBV status and immunosuppressive treatment were not correlated with OS. Our findings merit further investigation of EBV + PCNSL tumors and EBV-directed therapies.

The PO4-tential for Less Toxic CAR T-cell Therapies

Chimeric antigen receptor (CAR) T-cell therapy has yielded remarkable and durable responses for some patients with relapsed and refractory blood cancers. However, life-threatening toxicities such as immune effector cell-associated neurotoxicity syndrome (ICANS) remain a challenge for broad delivery of such therapies. In this issue, Tang and colleagues demonstrate an association between hypophosphatemia and CAR T cell-induced ICANS. Prospective studies are required to establish if phosphate monitoring is an early predictor for ICANS occurrence and if maintenance of phosphate levels has a role as a preventative strategy. See related article by Tang et al., p. 1433 (4).

Resolution of melanoma to PD-1 blockade but simultaneous rapid progression of concomitant chronic lymphocytic leukemia

Here we present a novel case of a patient with Chronic Lymphocytic Leukaemia (CLL) who received CTLA-4 and then PD-1 immune-checkpoint blockade (ICB) as treatment for concomitant metastatic melanoma. Whereas the metastatic melanoma was responsive to ICB, the CLL rapidly progressed (but responded to ICB cessation and ibrutinib). There were no new genetic mutational drivers to explain the altered clinical course. PD-1/PD-L1/PD-L2 and CTLA-4/CD80/CD86 expression was not increased in CLL B-cells, CD8+ or CD4+ T-cell subsets or monocytes. The patient’s CLL B-cells demonstrated strikingly prolonged in-vitro survival during PD-1 blockade, which was not observed in samples taken before or after ICB, or with other patients. To our knowledge, a discordant clinical course to ICB coupled with these biological features has not been reported in a patient with dual malignancies.

Abstract A17: The immune checkpoints TIGIT and PD-1 are markedly upregulated in NLPHL compared to classical Hodgkin Lymphoma

Hodgkin lymphoma (HL) comprises two distinct disease entities based on clinical, morphologic and genotypic characteristics. Relative to classical Hodgkin Lymphoma (cHL), nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is rare, and its tumor microenvironment (TME) is very poorly characterized. With the exception of rituximab, there are no targeted treatments nor advances in the treatment of NLPHL for decades. Unlike cHL, the utility of immune-checkpoint blockade (ICB) has not been evaluated in NLPHL. Diagnostic samples were collected from 49 NLPHL patients from 4 Australian centres and compared with stage-matched cHL patients (and with normal lymph nodes). An integrative transcriptomic, proteomic, T-cell clonal and functional analysis was performed to enable a comparison of the composition of the TME and its contribution to immune-evasion in NLPHL with cHL. 730 cancer-immune related genes were digitally quantified. Relative to cHL, gene set enrichment analysis identified T-cell receptor (TCR) and immune-checkpoint signaling pathway dysregulation in NLPHL. Most striking was prominent differential expression of the immune-transcriptome, particularly enrichment for programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) in NLPHL versus cHL. These were also over expressed compared to normal lymph nodes. Consistent with this, there was also upregulation of numerous T-cell markers (CD247, CD3D, GZMK, CD28, EOMES) in NLPHL. In contrast, immunosuppressive macrophage (CD163, CD36, CD68, COLEC12, MARCO) and regulatory T-cell genes (FOXP3) were higher in cHL. Importantly, PD-L1 and CD155 (respective ligands for PD-1 and TIGIT) were expressed at the surface of NLPHL and cHL malignant B-cells. Multispectral immunofluorescent microscopy showed intratumoral TIGIT+CD4+ and PD-1+CD4+ T-cells were markedly increased in NLPHL versus cHL and localised within NLPHL follicles. Expanded populations of intratumoral CD4+ T-cell clones were predominantly PD-1+ and frequently also TIGIT+. Multi-parameter flow cytometry and dimensionality reduction was used to establish the distribution of immune checkpoints within circulating T-cell subsets. PD-1+TIGIT+CD4+ T-cells were raised in circulating Treg, TH1 and TH2 subsets in NLPHL versus cHL, and PD-1+TIGIT+ TH2 T-cells displayed raised levels of the exhaustion marker EOMES, collectively indicating systemic T-cell dysfunction. To functionally demonstrate the utility of ICB to stimulate T-cells, an assay using cHL and/or NLPHL cell-lines co-cultured with a genetically engineered effector T-cell-line was developed. This showed that TIGIT/PD-1 dual-blockade was more effective than mono-blockade in inducing NLPHL and cHL tumor-directed CD4+ T-cell activation. Overall, our results indicate that immune-evasion mechanisms in NLPHL are distinct to those operative in cHL, with markedly greater T-cell, PD-1 and TIGIT dysregulation. PD-1 and/or TIGIT blockade warrants evaluation in NLPHL.

Citation Format: Jay Gunawardana, Soi C. Law, Muhammed B. Sabdia, Karolina Bednarska, Sandra Brosda, Andreea Zaharia, Hennes Tsang, Lilia M. de Long, Melinda Burgess, Dipti Talaulikar, Justina N. Lee, Emily Jude, Eliza A. Hawkes, Sanjiv Jain, Karthik Nath, Clare Gould, Fiona Swain, Joshua W. D. Tobin, Colm Keane, Simone Birch, Mohamed Shanavas, Cameron Snell, Maher K. Gandhi. The immune checkpoints TIGIT and PD-1 are markedly upregulated in NLPHL compared to classical Hodgkin Lymphoma [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A17.

CD4 T Cells: the complicated key to unlocking the immune environment of classical Hodgkin Lymphoma

Not available.

Intratumoral T-cell receptor repertoire is predictive of interim PET scan results in patients with diffuse large B-cell lymphoma treated with rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R-CHOP) chemoimmunotherapy

Objectives

A diverse intratumoral T‐cell receptor (TCR) repertoire is associated with improved survival in diffuse large B‐cell lymphoma (DLBCL) treated with rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R‐CHOP) chemoimmunotherapy. We explored the impact of intratumoral TCR repertoire on interim PET (iPET) done after four cycles of R‐CHOP, the relationships between intratumoral and circulating repertoire, and the phenotypes of expanded clonotypes.

Methods

We sequenced the third complementarity‐determining region of TCRβ in tumor samples, blood at pre‐therapy and after four cycles of R‐CHOP in 35 patients enrolled in ALLGNHL21 trial in high‐risk DLBCL. We correlated the TCR diversity metrics with iPET status, gene expression profiles and HLA‐class I genotypes. We then sequenced the FACS‐sorted peripheral blood T cells in six patients, and pentamer‐sorted EBV‐specific CD8⁺ T cells in one patient from this cohort.

Results

Compared with iPET⁻ patients, the intratumoral TCR repertoire in iPET⁺ patients was characterised by higher cumulative frequency of abundant clonotypes and higher productive clonality. There was a variable overlap between circulating and intratumoral repertoires, with the dominant intratumoral clonotypes more likely to be detected in the blood. The majority of shared clonotypes were CD8⁺ PD‐1^HI T cells, and CD8⁺ T cells had the largest clonal expansions in tumor and blood. In a patient with EBV⁺ DLBCL, EBV‐specific intratumoral clonotypes were trackable in the blood.

Conclusion

This study demonstrates that clonally expanded intratumoral TCR repertoires are associated with iPET⁺ and that the blood can be used to track tumor‐associated antigen‐specific clonotypes. These findings assist the rationale design and therapeutic monitoring of immunotherapeutic strategies in DLBCL.

Successful treatment of Epstein-Barr virus-associated primary central nervous system lymphoma due to post-transplantation lymphoproliferative disorder, with ibrutinib and third-party Epstein-Barr virus-specific T cells

Primary central nervous system lymphoma (PCNSL) occurring following organ transplantation (post-transplantation lymphoproliferative disorder [PTLD]) is a highly aggressive non-Hodgkin lymphoma. It is typically treated with high-dose methotrexate-based regimens. Outcomes are dismal and clinical trials are lacking. It is almost always Epstein-Barr virus (EBV) associated. Two patients (CA1-2) presented with EBV-associated PCNSL after renal transplant. CA1 was on hemodialysis and had prior disseminated cryptococcus and pseudomonas bronchiectasis, precluding treatment with methotrexate. CA2 was refractory to methotrexate. Both were treated off-label with the first-generation Bruton's tyrosine kinase inhibitor ibrutinib for 12 months. Cerebrospinal fluid penetration at therapeutic levels was confirmed in CA1 despite hemodialysis. Both patients entered remission by 2 months. Sequencing confirmed absence of genetic aberrations in human leukocyte antigen (HLA) class I/II and antigen-presentation/processing genes, indicating retention of the ability to present EBV-antigens. Between Weeks 10 and 13, they received third-party EBV-specific T cells for consolidation with no adverse effects. They remain in remission ≥34 months since therapy began. The strength of these findings led to an ongoing phase I study (ACTRN12618001541291).

Characterisation of immune checkpoints in Richter syndrome identifies LAG3 as a potential therapeutic target

Richter syndrome (RS), an aggressive lymphoma occurring in the context of chronic lymphocytic leukaemia/small lymphocytic lymphoma, is associated with poor prognosis when treated with conventional immunochemotherapy, therefore, improved treatments are required. Immune checkpoint blockade has shown efficacy in some B-cell malignancies and modest responses in early clinical trials for RS. We investigated the immune checkpoint profile of RS as a basis to inform rational therapeutic investigations in RS. Formalin-fixed, paraffin-embedded biopsies of RS (n = 19), de novo diffuse large B-cell lymphoma (DLBCL; n = 58), transformed indolent lymphomas (follicular [tFL], n = 16; marginal zone [tMZL], n = 24) and non-transformed small lymphocytic lymphoma (SLL; n = 15) underwent gene expression profiling using the NanoString Human Immunology panel. Copy number assessment was performed using next-generation sequencing. Immunohistochemistry (IHC) for LAG3 and PD-1 was performed. LAG3 gene expression was higher in RS compared to DLBCL (P = 0·0002, log2FC 1·96), tFL (P < 0·0001, log2FC 2·61), tMZL (P = 0·0004, log2FC 1·79) and SLL (P = 0·0057, log2FC 1·45). LAG3 gene expression correlated with the gene expression of human leukocyte antigen Class I and II, and related immune genes and immune checkpoints. IHC revealed LAG3 protein expression on both malignant RS cells and tumour-infiltrating lymphocytes. Our findings support the investigation of LAG3 inhibition to enhance anti-tumour responses in RS.

A cost-effectiveness analysis of front-line treatment strategies in early-stage follicular lymphoma

Recent data suggest the use of radiotherapy alone (RT) in Early-Stage Follicular Lymphoma is declining. Cost-effectiveness analysis of treatments has not been performed. We constructed a partitioning model (15-year horizon) to compare RT, combined-modality therapy (CMT) and immunochemotherapy with rituximab maintenance (ICT + RM) from a PET-staged cohort from the Australian Lymphoma Alliance. Lifetime direct health care costs, quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs) were calculated. AUD $75,000 was defined as the willingness-to-pay threshold (WTP). The direct healthcare costs were: RT $12,791, CMT $29,391 and ICT + RM $42,644. Compared with RT, CMT demonstrated minimal improvement in QALYs (+0.01) and an ICER well above the WTP threshold ($1,535,488). Compared with RT, ICT + RM demonstrated an improvement in QALYs (+0.41) with an ICER of $73,319. Modeling a 25% cost reduction with a rituximab biosimilar led to further ICER reductions with ICT + RM ($52,476). ICT + RM is cost-effective in early-stage FL from the Australian taxpayer perspective.

Targeted Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is the most common indolent B-cell lymphoma. Advanced stage disease is considered incurable and is characterized by a prolonged relapsing/remitting course. A significant minority have less favorable outcomes, particularly those with transformed or early progressive disease. Recent advances in our understanding of the unique genetic and immune biology of FL have led to increasingly potent and precise novel targeted agents, suggesting that a chemotherapy-future may one day be attainable. The current pipeline of new therapeutics is unprecedented. Particularly exciting is that many agents have non-overlapping modes of action, offering potential new combinatorial options and synergies. This review provides up-to-date clinical and mechanistic data on these new therapeutics. Ongoing dedicated attention to basic, translational and clinical research will provide further clarity as to when and how to best use these agents, to improve efficacy without eliciting unnecessary toxicity.

Ibrutinib for central nervous system lymphoma: the Australasian Lymphoma Alliance/MD Anderson Cancer Center experience

Primary and secondary central nervous system lymphomas (PCNSL/SCNSL) are aggressive rare malignancies with dismal outcomes. Encouraging data have emerged from Phase I/II clinical trials treating relapsed/refractory PCNSL/SCNSL with ibrutinib. We analysed 33 patients who received ibrutinib, alone or with other therapies, for PCNSL (n = 9) or SCNSL (n = 24). The objective response rate was 58% (complete response 55%). The median progression-free survival and overall survival for patients with PCNSL were both 3·1 months; for SCNSL, 10·2 and 11·5 months respectively. Only one invasive fungal infection was observed, despite concurrent or recent use of dexamethasone 8-16 mg daily in 14 patients (42%). Ibrutinib has encouraging activity in these aggressive malignancies.