Current Clinical Applications and Future Perspectives of Immune Checkpoint Inhibitors in Non-Hodgkin Lymphoma

Navigating between Scylla and Charybdis: A roadmap to do better than Pola-RCHP in DLBCL

In treating diffuse large B-cell lymphoma (DLBCL), oncologists have traditionally relied on the chemotherapy backbone of R-CHOP as standard of care. The two dangers that the hematologist must navigate between are the aggressive disease (Charybdis that in the absence of therapy systematically destroys all the ships) and the toxicity of the therapies (Scylla with its six monstrous heads that devours six crew members at a time), and hematologists have to navigate very carefully between both. Therefore, three different strategies were employed with the goal of improving cure rates: de-escalating regimens, escalating regimens, and replacement strategies. With a replacement strategy, a breakthrough in treatment was identified with polatuzumab vedotin (anti-CD79B antibody/drug conjugate) plus R-CHP. However, this regimen still did not achieve the elusive universal cure rate. Fortunately, advances in genomic and molecular technologies have allowed for an improved understanding of the heterogenous molecular nature of the disease to help develop and guide more targeted, precise, and individualized therapies. Additionally, new pharmaceutical technologies have led to the development of novel cellular therapies, such as chimeric antigen receptor (CAR) T-cell therapy, that could be more effective, while maintaining an acceptable safety profile. Thus, we aim to highlight the challenges of DLBCL therapy as well as the need to address therapeutic regimens eventually no longer tethered to a chemotherapy backbone. In the intersection of artificial intelligence and multi-omics (genomics, epigenomics, transcriptomics, proteomics, metabolomics), we propose the need to analyze multidimensional biologic datato launch a decisive attack against DLBCL in a targeted and individualized fashion.

Harnessing the Immune System: An Effective Way to Manage Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a heterogenous hematological disorder with malignant potential controlled by immunological characteristics of the tumor microenvironment. Rapid breakthrough in the molecular pathways has made immunological approaches the main anchor in the management of DLBCL, with or without chemotherapeutic agents. Rituximab was the first monoclonal antibody approved for the treatment of DLBCL. Following rituximab that transformed the therapeutic landscape, other novel immunological agents including chimeric antigen T-cell therapy have reshaped the management of relapsed/refractory DLBCL. However, resistance and refractory state remain a challenge in the management of DLBCL. For this literature review, we screened articles from Medline, Embase, Cochrane databases and the European/North American guidelines from March 2010 through October 2022 for DLBCL. Here we discuss immunological agents that will significantly affect future treatment of this aggressive type of lymphoma.

Dysfunctions of innate and adaptive immune tumor microenvironment in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a rare subtype of non-Hodgkin lymphoma characterized by malignant lymphoplasmacytic cells in the bone marrow (BM). To dissect the pathophysiology of WM, we evaluated clonal cells by mapping of B cell lymphomagenesis with adaptive and innate immune tumor microenvironment (TME) in the BM of WM patients using mass cytometry (CyTOF). In-depth immunophenotypic profiling of WM cells exhibited profound expansion of clonal cells in both unswitched and switched memory B cells and also plasma cells with aberrant expression variations. WM B lymphomagenesis was associated with reduction of most B cell precursors assessed with the same clonally restricted light chain and phenotypic changes. The immune TME was infiltrated by mature monocytes, neutrophils and adaptive T cells, preferentially subsets of effector T helper, effector CTL and effector memory CTL cells that were associated with superior overall survival (OS), in contrast to progenitors of T cells and myeloid/monocytic lineage subsets that were suppressed in WM cohort. Moreover, decrease in immature B and NKT cells was related to worse OS in WM patients. Innate and adaptive immune subsets of WM TME were modulated by immune checkpoints, including PD-1/PD-L1&PD-L2, TIGIT/PVR, CD137/CD137-L, CTLA-4, BTLA and KIR expression. The response of ibrutinib treatment to the reduction of clonal memory B cell was associated with high levels of immature B cells and effector memory CTL cells. Our study demonstrates that CyTOF technology is a powerful approach for characterizing the pathophysiology of WM at various stages, predicting patient risk and monitoring the effectiveness of treatment strategies.

A systematic review and meta-analysis of immune checkpoint therapy in relapsed or refractory non-Hodgkin lymphoma; a friend or foe?

Over the last decades, a revolution has occurred in oncology with the development of immune checkpoint inhibitors (ICIs). Following tremendous successes in solid tumors, interest has risen to explore these inhibitors in hematologic malignancies; while Hodgkin's lymphoma (HL) has shown overwhelming achievements, available data on different types of non-Hodgkin's lymphoma (NHL) vary considerably. To the best of our knowledge, no meta-analysis has assessed the efficacy and safety of ICI therapy in relapsed or refractory NHL patients. Meta-analysis of the included studies (n = 29) indicated PD-1 may probably be the more attractive ICI target rather than PD-L1 and CTLA-4 in NHL patients. Also, there is a plausible correlation between NHL subtypes and response to ICI therapy. While MF, ENKTL, RT, and PMBCL showed promising responses to ICI monotherapy, neither FL nor DLBCL had satisfactory responses; further necessitating novel strategies such as the application of ICIs in combination with other treatment strategies. Notably, among different combinations, BTK inhibitors showed an obvious improvement as compared to ICI monotherapy in both FL and DLBCL, however, the best results were obtained when ICI was combined with anti-CD20 monoclonal antibodies. Finally, while most NHL patients who received ICI treatment have experienced mild AEs, larger trials with long-term follow-up are required to confirm the safety, as well as the efficacy, of ICI therapy in NHL patients.

Targeting CD47 enhanced the antitumor immunity of PD-L1 blockade in B-cell lymphoma

Background: Only a subset of B-cell lymphoma (BCL) patients can benefit from immune checkpoint inhibitors targeting PD-1/PD-L1. Materials & methods: In the A20 model, SIRPα-Fc and anti-PD-L1 were employed to target CD47 and PD-L1 simultaneously. Flow cytometry, immunofluorescence and quantitative polymerase chain reaction were used to unravel the potential mechanisms. Results: Simultaneously targeting CD47 and PD-L1 activated CD8⁺ T cells with an increased release of effector molecules. Furthermore, infiltration of F4/80⁺iNOS⁺ M1 macrophages was enhanced by the dual therapy. Conclusion: Anti-CD47 therapy could sensitize BCL tumors to anti-PD-L1 therapy in a CD8⁺ T-cell- and M1-macrophage-dependent manner by promoting cytotoxic lymphocyte infiltration, which may provide a potential strategy for BCL treatment by simultaneously targeting CD47 and PD-L1.

Research progress of therapeutic effects and drug resistance of immunotherapy based on PD-1/PD-L1 blockade

The binding of programmed death-1 (PD-1) on the surface of T cells and PD-1 ligand 1 (PD-L1) on tumor cells can prevent the immune-killing effect of T cells on tumor cells and promote the immune escape of tumor cells. Therefore, immune checkpoint blockade targeting PD-1/PD-L1 is a reliable tumor therapy with remarkable efficacy. However, the main challenges of this therapy are low response rate and acquired resistance, so that the outcomes of this therapy are usually unsatisfactory. This review begins with the description of biological structure of the PD-1/PD-L1 immune checkpoint and its role in a variety of cells. Subsequently, the therapeutic effects of immune checkpoint blockers (PD-1 / PD-L1 inhibitors) in various tumors were introduced and analyzed, and the reasons affecting the function of PD-1/PD-L1 were systematically analyzed. Then, we focused on analyzing, sorting out and introducing the possible underlying mechanisms of primary and acquired resistance to PD-1/PD-L1 blockade including abnormal expression of PD-1/PD-L1 and some factors, immune-related pathways, tumor immune microenvironment, and T cell dysfunction and others. Finally, promising therapeutic strategies to sensitize the resistant patients with PD-1/PD-L1 blockade treatment were described. This review is aimed at providing guidance for the treatment of various tumors, and highlighting the drug resistance mechanisms to offer directions for future tumor treatment and improvement of patient prognosis.

Single-cell RNA-sequencing reveals predictive features of response to pembrolizumab in Sézary syndrome

The PD-1 inhibitor pembrolizumab is effective in treating Sézary syndrome, a leukemic variant of cutaneous T-cell lymphoma. Our purpose was to investigate the effects of pembrolizumab on healthy and malignant T cells in Sézary syndrome and to discover characteristics that predict pembrolizumab response. Samples were analyzed before and after 3 weeks of pembrolizumab treatment using single-cell RNA-sequencing of 118,961 peripheral blood T cells isolated from six Sézary syndrome patients. T-cell receptor clonotyping, bulk RNA-seq signatures, and whole-exome data were integrated to classify malignant T-cells and their underlying subclonal heterogeneity. We found that responses to pembrolizumab were associated with lower KIR3DL2 expression within Sézary T cells. Pembrolizumab modulated Sézary cell gene expression of T-cell activation associated genes. The CD8 effector populations included clonally expanded populations with a strong cytotoxic profile. Expansions of CD8 terminal effector and CD8 effector memory T-cell populations were observed in responding patients after treatment. We observed intrapatient Sézary cell heterogeneity including subclonal segregation of a coding mutation and copy number variation. Our study reveals differential effects of pembrolizumab in both malignant and healthy T cells. These data support further study of KIR3DL2 expression and CD8 immune populations as predictive biomarkers of pembrolizumab response in Sézary syndrome.

Combination of Atezolizumab and Tazemetostat in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Results From a Phase Ib Study

BACKGROUND

The combination of atezolizumab, a monoclonal antibody that targets programmed death-ligand 1 (PD-L1) and inhibits the interaction between PD-L1 and its receptors, and tazemetostat, an EZH2 inhibitor, may lead to selective epigenetic reprogramming, alter the tumor microenvironment, and provide additive or synergistic response to patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL).

MATERIALS AND METHODS

This was an open-label, phase Ib study assessing the safety, tolerability, and preliminary efficacy of atezolizumab plustazemetostat in patients with R/R DLBCL. Atezolizumab (1200 mg) was administered via intravenous (IV) infusion on day 1 of each cycle and tazemetostat (800 mg) was given orally twice daily (BID) on days 1 to 21. Primary endpoints were safety and tolerability, and to identify a recommended phase II dose (RP2D) for atezolizumab. Secondary efficacy endpoints included response rate and duration of response.

RESULTS

A total of 43 patients were enrolled, receiving a median of 3 prior lines of treatment (range: 1-9). The RP2D for atezolizumab was 1200 mg IV infusion every 3 weeks in combination with tazemetostat 800 mg BID. At the RP2D, adverse events reported in ≥20% patients were anemia(11 patients [26%]), fatigue (10 patients [23%]), and nausea (10 patients [23%]). Overall response rate was 16% (complete response rate: 7%). Median progression-free survival was 2 months (range: 0-24) and median overall survival was 13 months (range: 1-29).

CONCLUSIONS

The combination of atezolizumab and tazemetostat was determined to be safe and tolerable. However, anti-tumor activity of the combination was modest.

Translating the Biology of Diffuse Large B-cell Lymphoma Into Treatment

Diffuse large B-cell lymphoma (DLBCL) is characterized by clinical and molecular heterogeneity; however, this heterogeneity is rarely taken into account by standard-of-care treatment approaches. While the disease was traditionally classified based on transcriptome signatures purporting the tumor cell of origin, recent classification systems have further differentiated these subtypes into clusters based on molecular and genetic features. Alongside a better understanding of the biology of the disease and the signaling pathways involved, emerging therapeutic agents may be better aimed at attacking distinct disease subsets. It is hoped that molecular subtyping at diagnosis will allow patients to be allocated to the appropriate treatment that targets their specific disease subtype, thus advancing the promise of precision medicine in lymphoma, an approach that is most needed. For high-risk disease subsets, this is particularly important, and much research is still needed to develop agents effective in this population. Here, we review recent advances in DLBCL biology and how they can be translated into clinical care.

A phase-II study of atezolizumab in combination with obinutuzumab or rituximab for relapsed or refractory mantle cell or marginal zone lymphoma or Waldenström's macroglobulinemia

We report efficacy, safety and biomarker data from a phase-II study evaluating atezolizumab (eight 21-day cycle as induction therapy) in combination with obinutuzumab in patients with relapsed/refractory mantle cell lymphoma (MCL, n = 30) or Waldenström's macroglobulinemia (WM, n = 4), and in combination with rituximab in patients with marginal zone lymphoma (MZL, n = 21). All patients received atezolizumab monotherapy as maintenance for ≤10 cycles. Objective response rates at end of induction were 16.7% (MCL) and 42.9% (MZL), with no responses in WM. Median duration of response was 6.8 months (range 5.7-not estimable) for MCL and not reached for MZL. Treatment-emergent adverse events (TEAEs) occurred in 93.3%, 95.2% and 100% of MCL, MZL and WM patients, respectively. One fatal TEAE (pneumonia) occurred in each of the MCL and MZL groups. Biomarker analysis highlighted the importance of characterizing the immune environment to optimize efficacy of immunotherapy regimens.Trial registration details: EudraCT: 2016-003579-22.