NK cell activation and recovery of NK cell subsets in lymphoma patients after obinutuzumab and lenalidomide treatment

Increased TIGIT expression correlates with impaired NK cell function in diffuse large B-cell lymphoma

Purpose

This study aims to investigate the status of natural killer (NK) cells and the role of T-cell immunoreceptor with Ig and ITIM domains (TIGIT)-mediated regulation in diffuse large B-cell lymphoma (DLBCL).

Methods

Peripheral blood samples from 30 newly diagnosed DLBCL patients and 25 healthy controls were collected. Multiparametric flow cytometry was used to analyze the expression levels of TIGIT and its family molecules (CD226 and CD96) on NK cells, as well as to assess NK cell phenotype and function. The restorative effects of TIGIT blockade on NK cell cytotoxicity were evaluated through in vitro functional assays and in vivo animal models.

Results

Compared to healthy controls, DLBCL patients exhibited significantly reduced percentages and absolute numbers of NK cells. TIGIT expression was markedly upregulated on NK cells in DLBCL patients, while CD226 expression was downregulated; however, no significant difference in CD96 expression was observed. These alterations were associated with impaired NK cell function in DLBCL patients, including reduced secretion of activation factors such as granzyme B, perforin, and CD107a. Importantly, TIGIT blockade significantly enhanced the cytotoxic activity of NK cells against DLBCL cells in both in vitro and in vivo settings.

Conclusion

Dysregulated expression of TIGIT and its family molecules on NK cells contributes to NK cell dysfunction and promotes tumor immune escape in DLBCL. These findings highlight TIGIT as a promising therapeutic target for restoring NK cell-mediated antitumor immunity in DLBCL.

Natural Killer cells at the frontline in the fight against cancer

Natural Killer (NK) cells are innate immune cells that play a pivotal role as first line defenders in the anti-tumor response. To prevent tumor development, NK cells are searching for abnormal cells within the body and appear to be key players in immunosurveillance. Upon recognition of abnormal cells, NK cells will become activated to destroy them. In order to fulfill their anti-tumoral function, they rely on the secretion of lytic granules, expression of death receptors and production of cytokines. Additionally, NK cells interact with other cells in the tumor microenvironment. In this review, we will first focus on NK cells' activation and cytotoxicity mechanisms as well as NK cells behavior during serial killing. Lastly, we will review NK cells' crosstalk with the other immune cells present in the tumor microenvironment.

Identification of a novel form of caspase-independent cell death triggered by BH3-mimetics in diffuse large B-cell lymphoma cell lines

BH3-mimetics represent promising anti-cancer agents in tumors that rely on the anti-apoptotic function of B-Cell Lymphoma 2 (BCL2) proteins, particularly in leukemia and lymphoma cells primed for apoptosis. Mechanistically, BH3-mimetics may displace pro-apoptotic binding partners thus inducing BAX/BAK-mediated mitochondrial permeabilization followed by cytochrome c release, activation of the caspase cascade and apoptosis. Here, we describe a novel mode of caspase-independent cell death (CICD) induced by BH3-mimetics in a subset of diffuse large B-cell lymphoma (DLBCL) cells. Of note, rather than occurring via necroptosis, CICD induced immediately after mitochondrial permeabilization was associated with transcriptional reprogramming mediated by activation of c-Jun N-terminal Kinase (JNK) signaling and Activator Protein 1 (AP1). Thereby, CICD resulted in the JNK/AP1-mediated upregulation of inflammatory chemokines and increased migration of cytotoxic Natural Killer (NK) cells. Taken together, our study describes a novel mode of CICD triggered by BH3-mimetics that may alter the immune response towards dying cells.

Ex Vivo Expanded Cord Blood Natural Killer Cells Combined with Rituximab and High-Dose Chemotherapy and Autologous Stem Cell Transplantation for B Cell Non-Hodgkin Lymphoma

Relapse is the major cause of failure of high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT) for B cell non-Hodgkin lymphomas (B-NHL). Improvement strategies include use in combination with effective immunotherapies. We hypothesized that the combination of rituximab/HDC/ASCT with expanded cord blood (CB)-derived natural killer (NK) cells is safe and active in B-NHL. Patients with B-NHL age 15 to 70 years and appropriate ASCT candidates were eligible for the study. The CB units were selected without considering HLA match with the recipient. The CB NK cells were expanded from day -19 to day -5. Treatment included rituximab on days -13 and -7, BEAM (carmustine/etoposide/cytarabine/melphalan) on days -13 to -7, lenalidomide on days -7 to -2, CB NK infusion (108/kg) on day -5, and ASCT (day 0). The primary endpoint was 30-day treatment-related mortality (TRM); secondary endpoints included relapse-free survival (RFS), overall survival (OS), and persistence of CB NK cells. We enrolled 20 patients. CB NK cells were expanded a median of 1552-fold with >98% purity and >96% viability. We saw no adverse events attributable to the CB NK cells and 0% 30-day TRM. At median follow-up of 47 months, the RFS and OS rates were 53% and 74%, respectively. CB NK cells were detectable in blood for 2 weeks, independent of HLA-mismatch status. CD16 expression in donor NK cells was correlated favorably with outcome, and homozygosity for the high-affinity CD16 variant (158 V/V) in CB, but not recipient, NK cells was correlated with better outcomes. Our data indicate that the combination of expanded and highly purified CB-derived NK cells with HDC/ASCT for B-NHL is safe. CD16 expression in donor NK cells, particularly if homozygous for the high-affinity CD16 variant, was correlated with better outcomes.

NK cells in peripheral blood carry trogocytosed tumor antigens from solid cancer cells

The innate immune lymphocyte lineage natural killer (NK) cell infiltrates tumor environment where it can recognize and eliminate tumor cells. NK cell tumor infiltration is linked to patient prognosis. However, it is unknown if some of these antitumor NK cells leave the tumor environment. In blood-borne cancers, NK cells that have interacted with leukemic cells are recognized by the co-expression of two CD45 isoforms (CD45RARO cells) and/or the plasma membrane presence of tumor antigens (Ag), which NK cells acquire by trogocytosis. We evaluated solid tumor Ag uptake by trogocytosis on NK cells by performing co-cultures in vitro. We analyzed NK population subsets by unsupervised dimensional reduction techniques in blood samples from breast tumor (BC) patients and healthy donors (HD). We confirmed that NK cells perform trogocytosis from solid cancer cells in vitro. The extent of trogocytosis depends on the target cell and the antigen, but not on the amount of Ag expressed by the target cell or the sensitivity to NK cell killing. We identified by FlowSOM (Self-Organizing Maps) several NK cell clusters differentially abundant between BC patients and HD, including anti-tumor NK subsets with phenotype CD45RARO+CD107a+. These analyses showed that bona-fide NK cells that have degranulated were increased in patients and, additionally, these NK cells exhibit trogocytosis of solid tumor Ag on their surface. However, the frequency of NK cells that have trogocytosed is very low and much lower than that found in hematological cancer patients, suggesting that the number of NK cells that exit the tumor environment is scarce. To our knowledge, this is the first report describing the presence of solid tumor markers on circulating NK subsets from breast tumor patients. This NK cell immune profiling could lead to generate novel strategies to complement established therapies for BC patients or to the use of peripheral blood NK cells in the theranostic of solid cancer patients after treatment.

A phase 1/2 study of lenalidomide and obinutuzumab with CHOP for newly diagnosed DLBCL

Diffuse large B-cell lymphoma (DLBCL) can be cured with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP); however, one-third of patients experience refractory or relapsed disease. Studies comparing R-CHOP with modified regimens replacing R with obinutuzumab (O) or adding lenalidomide (L) did not result in improved outcomes; however, L and O together may enhance natural killer-cell mediated antibody-dependent cellular toxicity when paired with CHOP. Here, we report on a phase 1b/2 study of 53 patients with newly diagnosed DLBCL who received 6 cycles of LO-CHOP. The end of treatment overall and complete response rates of the 50 evaluable patients were 98% and 90%, respectively. After a median follow-up of 4.5 years, the 4-year progression free and overall survival rates were 87.4% and 91.3%, respectively. Grade 3 to 4 adverse events were experienced by 70% of patients, including neutropenia (38%), thrombocytopenia (17%), fatigue (13%), and neutropenic fever (13%). Of the 33 patients profiled with circulating tumor DNA (ctDNA) sequencing, 31 (94%) had detectable pretreatment ctDNA with cancer personalized profiling by deep sequencing, 24 (73%) were classifiable by the LymphGen classifier, and 15/20 (75%) and 12/17 (71%) patients achieved early and major molecular responses after 1 and 2 cycles, respectively. Using phased variant enrichment and detection sequencing, 16/18 evaluable patients (89%) showed no detectable ctDNA after at least 5 cycles of LO-CHOP. LO-CHOP demonstrates high efficacy and tolerability in newly diagnosed DLBCL, leading to a high rate of undetectable minimal residual disease by ctDNA. This trial has been registered at www.clinicaltrials.gov as NCT02529852.

Management of indolent B-cell Lymphomas: A review of approved and emerging targeted therapies

The indolent B-cell non-Hodgkin lymphomas (B-NHL) comprise a heterogenous group of lymphoproliferative disorders characterized by slow growth kinetics and a relapsing/remitting course. Management has, until recently, been uniform across all indolent B-NHL subtypes. Improving insight into pathophysiological and molecular features of each disease has led to development of several targeted therapies. Consequently, each subtype must now be considered an individual entity. In this review, we consider the three commonest indolent B-NHLs: follicular lymphoma, marginal zone lymphoma and Waldenstrom's macroglobulinemia and review in detail the data on approved and emerging targeted therapeutic agents for each B-NHL subtype.

The SUMOylation inhibitor subasumstat potentiates rituximab activity by IFN1-dependent macrophage and NK cell stimulation

Small ubiquitin-like modifier (SUMO) is a member of a ubiquitin-like protein superfamily. SUMOylation is a reversible posttranslational modification that has been implicated in the regulation of various cellular processes including inflammatory responses and expression of type 1 interferons (IFN1). In this report, we have explored the activity of the selective small molecule SUMOylation inhibitor subasumstat (TAK-981) in promoting antitumor innate immune responses. We demonstrate that treatment with TAK-981 results in IFN1-dependent macrophage and natural killer (NK) cell activation, promoting macrophage phagocytosis and NK cell cytotoxicity in ex vivo assays. Furthermore, pretreatment with TAK-981 enhanced macrophage phagocytosis or NK cell cytotoxicity against CD20+ target cells in combination with the anti-CD20 antibody rituximab. In vivo studies demonstrated enhanced antitumor activity of TAK-981 and rituximab in CD20+ lymphoma xenograft models. Combination of TAK-981 with anti-CD38 antibody daratumumab also resulted in enhanced antitumor activity. TAK-981 is currently being studied in phase 1 clinical trials (#NCT03648372, #NCT04074330, #NCT04776018, and #NCT04381650; www.clinicaltrials.gov) for the treatment of patients with lymphomas and solid tumors.

NK Cells Acquire CCR5 and CXCR4 by Trogocytosis in People Living with HIV-1

NK cells play a major role in the antiviral immune response, including against HIV-1. HIV-1 patients have impaired NK cell activity with a decrease in CD56^dim NK cells and an increase in the CD56⁻CD16⁺ subset, and recently it has been proposed that a population of CD56⁺NKG2C⁺KIR⁺CD57⁺ cells represents antiviral memory NK cells. Antiretroviral therapy (ART) partly restores the functional activity of this lymphocyte lineage. NK cells when interacting with their targets can gain antigens from them by the process of trogocytosis. Here we show that NK cells can obtain CCR5 and CXCR4, but barely CD4, from T cell lines by trogocytosis in vitro. By UMAP (Uniform Manifold Approximation and Projection), we show that aviremic HIV-1 patients have unique NK cell clusters that include cells expressing CCR5, NKG2C and KIRs, but lack CD57 expression. Viremic patients have a larger proportion of CXCR4⁺ and CCR5⁺ NK cells than healthy donors (HD) and this is largely increased in CD107⁺ cells, suggesting a link between degranulation and trogocytosis. In agreement, UMAP identified a specific NK cell cluster in viremic HIV-1 patients, which contains most of the CD107a⁺, CCR5⁺ and CXCR4⁺ cells. However, this cluster lacks NKG2C expression. Therefore, NK cells can gain CCR5 and CXCR4 by trogocytosis, which depends on degranulation.

Identification of molecular subtypes and a novel prognostic model of diffuse large B-cell lymphoma based on a metabolism-associated gene signature

Background

Diffuse large B cell lymphoma (DLBCL) is the most common lymphoma in adults. Metabolic reprogramming in tumors is closely related to the immune microenvironment. This study aimed to explore the interactions between metabolism-associated genes (MAGs) and DLBCL prognosis and their potential associations with the immune microenvironment.

Methods

Gene expression and clinical data on DLBCL patients were obtained from the GEO database. Metabolism-associated molecular subtypes were identified by consensus clustering. A prognostic risk model containing 14 MAGs was established using Lasso-Cox regression in the GEO training cohort. It was then validated in the GEO internal testing cohort and TCGA external validation cohort. GO, KEGG and GSVA were used to explore the differences in enriched pathways between high- and low-risk groups. ESTIMATE, CIBERSORT, and ssGSEA analyses were used to assess the immune microenvironment. Finally, WGCNA analysis was used to identify two hub genes among the 14 model MAGs, and they were preliminarily verified in our tissue microarray (TMA) using multiple fluorescence immunohistochemistry (mIHC).

Results

Consensus clustering divided DLBCL patients into two metabolic subtypes with significant differences in prognosis and the immune microenvironment. Poor prognosis was associated with an immunosuppressive microenvironment. A prognostic risk model was constructed based on 14 MAGs and it was used to classify the patients into two risk groups; the high-risk group had poorer prognosis and an immunosuppressive microenvironment characterized by low immune score, low immune status, high abundance of immunosuppressive cells, and high expression of immune checkpoints. Cox regression, ROC curve analysis, and a nomogram indicated that the risk model was an independent prognostic factor and had a better prognostic value than the International Prognostic Index (IPI) score. The risk model underwent multiple validations and the verification of the two hub genes in TMA indicated consistent results with the bioinformatics analyses.

Conclusions

The molecular subtypes and a risk model based on MAGs proposed in our study are both promising prognostic classifications in DLBCL, which may provide novel insights for developing accurate targeted cancer therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03393-9.

Prospects in the management of patients with follicular lymphoma beyond first-line therapy

The management of patients with relapsed or refractory follicular lymphoma has evolved markedly in the last decade, with the availability of new classes of agents (phosphoinositide 3-kinase inhibitors, immunomodulators, epigenetic therapies, and chimeric antigen receptor T cells) supplementing the multiple approaches already available (cytotoxic agents, anti-CD20 antibodies, radiation therapy, radioimmunotherapy, and autologous and allogeneic transplants). The diversity of clinical scenarios, the flood of data derived from phase II studies, and the lack of randomized studies comparing treatment strategies preclude firm recommendations and require personalized decisions. Patients with early progression require specific attention given the risk of histological transformation and their lower response to standard therapies. In sequencing therapies, one must consider prior treatment regimens and the potential need for future lines of therapy. Careful evaluation of risks and expected benefits of available options, which vary depending on location and socioeconomics, should be undertaken, and should incorporate the patient's goals. Preserving quality of life for these patients is essential, given the likelihood of years to decades of survival and the possibility of multiple lines of therapy. The current landscape is likely to continue evolving rapidly with other effective agents emerging (notably bispecific antibodies and other targeted therapies), and multiple combinations being evaluated. It is hoped that new treatments under development will achieve longer progression-free intervals and minimize toxicity. A better understanding of disease biology and the mechanisms of these different agents should provide further insights to select the optimal therapy at each stage of disease.

The use of tafasitamab in diffuse large B-cell lymphoma

Patients who relapse or are refractory after first-line therapy for diffuse large B-cell lymphoma (DLBCL) frequently have poor prognoses, especially when they are not candidates for autologous stem cell transplant (ASCT). Tafasitamab is a humanized monoclonal anti-CD19 antibody that has recently been approved by the FDA in combination with lenalidomide for the treatment of relapsed/refractory (R/R) DLBCL in patients who are not eligible for ASCT. Tafasitamab has an Fc region which has been modified to have an increased affinity for Fcγ receptors, to potentiate antibody-dependent cellular cytotoxicity and antibody-dependent cell-mediated phagocytosis. Here, we review the development, mode of action and clinical data for tafasitamab in combination with lenalidomide in R/R DLBCL, and discuss the various ways in which this novel antibody could be utilized in the treatment sequence to improve clinical outcomes for patients with DLBCL.

Lenalidomide triggers T-cell effector functions in vivo in patients with follicular lymphoma

The immunomodulatory drug lenalidomide is used in patients with follicular lymphoma (FL) with the aim of stimulating T-cell antitumor immune response. However, little is known about the effects of lenalidomide on T-cell biology in vivo in patients with FL. We thus undertook an extensive longitudinal immunologic study, including phenotypic, transcriptomic, and functional analyses, on 44 first-line and 27 relapsed/refractory patients enrolled in the GALEN trial (Obinutuzumab Combined With Lenalidomide for Relapsed or Refractory Follicular B-Cell Lymphoma) to test the efficacy of lenalidomide and obinutuzumab combination in patients with FL. Lenalidomide rapidly and transiently induced an activated T-cell phenotype, including HLA-DR, Tim-3, CD137, and programmed cell death protein 1 (PD-1) upregulation. Furthermore, sequential RNA-sequencing of sorted PD-1+ and PD-1- T-cell subsets revealed that lenalidomide triggered a strong enrichment for several gene signatures related to effector memory T-cell features, including proliferation, antigen receptor signaling, and immune synapse restoration; all were validated at the phenotypic level and with ex vivo functional assays. Correlative analyses pinpointed a negative clinical impact of high effector T-cell and regulatory T-cell percentages before and during treatment. Our findings bring new insight in lenalidomide mechanisms of action at work in vivo and will fuel a new rationale for the design of combination therapies.

Dissecting the NK Cell Population in Hematological Cancers Confirms the Presence of Tumor Cells and Their Impact on NK Population Function

The lymphocyte lineage natural killer (NK) cell is part of the innate immune system and protects against pathogens and tumor cells. NK cells are the main cell effectors of the monoclonal antibodies (mAbs) that mediates antibody-dependent cell cytotoxicity (ADCC). Hence, it is relevant to understand NK physiology and status to investigate the biological effect of mAbs in the clinic. NK cells are heterogeneous with multiple subsets that may have specific activity against different attacks. The presence of viral-sculpted NK cell populations has already been described, but the presence of cancer-sculpted NK cells remains unknown. Cancer induces a broad NK cell dysfunction, which has not been linked to a specific population. Here, we investigated the NK cell population by Uniform Manifold Approximation and Projection (UMAP) embed maps in Hodgkin lymphoma (HL) and acute myeloid leukemia (AML) patients at diagnosis and at least 30 days after treatment, which correlates with tumor cell clearance. We found that the NK lineage largely responded to the tumor by generating antitumor NK cells and renewing the population with a subset of immature NK cells. However, we failed to identify a specific "memory-like" subset with the NK cell markers used. Moreover, in patients in relapse, we found essentially the same NK populations as those found at diagnosis, suggesting that NK cells equally respond to the first or second tumor rise. Finally, we observed that previous cytomegalovirus (CMV) infection largely affects the tumor-associated changes in NK population, but the CMV-associated CD57⁺NKG2C⁺ NK cell population does not appear to play any role in tumor immunity.

Expanded and activated allogeneic NK cells are cytotoxic against B-chronic lymphocytic leukemia (B-CLL) cells with sporadic cases of resistance

Adoptive transfer of allogeneic natural killer (NK) cells is becoming a credible immunotherapy for hematological malignancies. In the present work, using an optimized expansion/activation protocol of human NK cells, we generate expanded NK cells (eNK) with increased expression of CD56 and NKp44, while maintaining that of CD16. These eNK cells exerted significant cytotoxicity against cells from 34 B-CLL patients, with only 1 sample exhibiting resistance. This sporadic resistance did not correlate with match between KIR ligands expressed by the eNK cells and the leukemic cells, while cells with match resulted sensitive to eNK cells. This suggests that KIR mismatch is not relevant when expanded NK cells are used as effectors. In addition, we found two examples of de novo resistance to eNK cell cytotoxicity during the clinical course of the disease. Resistance correlated with KIR-ligand match in one of the patients, but not in the other, and was associated with a significant increase in PD-L1 expression in the cells from both patients. Treatment of one of these patients with idelalisib correlated with the loss of PD-L1 expression and with re-sensitization to eNK cytotoxicity. We confirmed the idelalisib-induced decrease in PD-L1 expression in the B-CLL cell line Mec1 and in cultured cells from B-CLL patients. As a main conclusion, our results reinforce the feasibility of using expanded and activated allogeneic NK cells in the treatment of B-CLL.

A prognostic gene model of immune cell infiltration in diffuse large B-cell lymphoma

Background

Immune cells in the tumor microenvironment are an important prognostic indicator in diffuse large B-cell lymphoma (DLBCL). However, information on the heterogeneity and risk stratification of these cells is limited. We sought to develop a novel immune model to evaluate the prognostic intra-tumoral immune landscape of patients with DLBCL.

Methods

The ESTIMATE and CIBERSORT algorithms were used to estimate the numbers of 22 infiltrating immune cells based on the gene expression profiles of 229 patients with DLBCL who were recruited from a public database. The least absolute shrinkage and selection operator (Lasso) penalized regression analyses and nomogram model were used to construct and evaluate the prognostic immunoscore (PIS) model for overall survival prediction. An immune gene prognostic score (IGPS) was generated by Gene Set Enrichment Analysis (GSEA) and Cox regression analysis was and validated in an independent NCBI GEO dataset (GSE10846).

Results

A higher proportion of activated natural killer cells was associated with a poor outcome. A total of five immune cells were selected in the Lasso model and DLBCL patients with high PIS showed a poor prognosis (hazard ratio (HR) 2.16; 95% CI [1.33-3.50]; P = 0.002). Differences in immunoscores and their related outcomes were attributed to eight specific immune genes involved in the cytokine-cytokine receptor interaction and chemokine signaling pathways. The IGPS based on a weighted formula of eight genes is an independent prognostic factor (HR: 2.14, 95% CI [1.40-3.28]), with high specificity and sensitivity in the validation dataset.

Conclusions

Our findings showed that a PIS model based on immune cells is associated with the prognosis of DLBCL. We developed a novel immune-related gene-signature model associated with the PIS model and enhanced the prognostic functionality for the prediction of overall survival in patients with DLBCL.

Immunomodulatory Agents in Follicular Lymphoma

New treatment strategies in follicular lymphoma (FL) are driven by a deeper understanding of microenvironmental cues supporting lymphomagenesis, chemoresistance, and immuno-escape. These immune-mediated signaling pathways contribute to initial learnings and clinical successes with lenalidomide, the first, oral, non-chemotherapeutic immunomodulatory drug, combined with anti-CD20 antibodies. This combination of lenalidomide with rituximab showed similar efficacy to chemoimmunotherapy (CIT) in first-line patients requiring therapy, and is approved in relapsed/refractory FL. We review the biology supporting the rationale for adequate inhibitory receptor/ligand pathways targeting the tissue immune microenvironment of FL cells, and potential immunomodulating combinations to replace CIT in the near future.

Unleashing Natural Killer Cells in the Tumor Microenvironment-The Next Generation of Immunotherapy?

The emergence of immunotherapy for cancer treatment bears considerable clinical promise. Nevertheless, many patients remain unresponsive, acquire resistance, or suffer dose-limiting toxicities. Immune-editing of tumors assists their escape from the immune system, and the tumor microenvironment (TME) induces immune suppression through multiple mechanisms. Immunotherapy aims to bolster the activity of immune cells against cancer by targeting these suppressive immunomodulatory processes. Natural Killer (NK) cells are a heterogeneous subset of immune cells, which express a diverse array of activating and inhibitory germline-encoded receptors, and are thus capable of directly targeting and killing cancer cells without the need for MHC specificity. Furthermore, they play a critical role in triggering the adaptive immune response. Enhancing the function of NK cells in the context of cancer is therefore a promising avenue for immunotherapy. Different NK-based therapies have been evaluated in clinical trials, and some have demonstrated clinical benefits, especially in the context of hematological malignancies. Solid tumors remain much more difficult to treat, and the time point and means of intervention of current NK-based treatments still require optimization to achieve long term effects. Here, we review recently described mechanisms of cancer evasion from NK cell immune surveillance, and the therapeutic approaches that aim to potentiate NK function. Specific focus is placed on the use of specialized monoclonal antibodies against moieties on the cancer cell, or on both the tumor and the NK cell. In addition, we highlight newly identified mechanisms that inhibit NK cell activity in the TME, and describe how biochemical modifications of the TME can synergize with current treatments and increase susceptibility to NK cell activity.

Non-Genetically Improving the Natural Cytotoxicity of Natural Killer (NK) Cells

The innate lymphocyte lineage natural killer (NK) is now the target of multiple clinical applications, although none has received an agreement from any regulatory agency yet. Transplant of naïve NK cells has not proven efficient enough in the vast majority of clinical trials. Hence, new protocols wish to improve their medical use by producing them from stem cells and/or modifying them by genetic engineering. These techniques have given interesting results but these improvements often hide that natural killers are mainly that: natural. We discuss here different ways to take advantage of NK physiology to improve their clinical activity without the need of additional modifications except for in vitro activation and expansion and allograft in patients. Some of these tactics include combination with monoclonal antibodies (mAb), drugs that change metabolism and engraftment of specific NK subsets with particular activity. Finally, we propose to use specific NK cell subsets found in certain patients that show increase activity against a specific disease, including the use of NK cells derived from patients.

Polyoxidonium® Activates Cytotoxic Lymphocyte Responses Through Dendritic Cell Maturation: Clinical Effects in Breast Cancer

Immunotherapy, which is seen as a major tool for cancer treatment, requires, in some cases, the presence of several agents to maximize its effects. Adjuvants can enhance the effect of other agents. However, despite their long-time use, only a few adjuvants are licensed today, and their use in cancer treatment is rare. Azoximer bromide, marketed under the trade name Polyoxidonium® (PO), is a copolymer of N-oxidized 1,4-ethylenepiperazine and (N-carboxyethyl)-1,4-ethylene piperazinium bromide. It has been described as an immune adjuvant and immunomodulator that is clinically used with excellent tolerance. PO is used in the treatment and prophylaxis of diseases connected with damage to the immune system, and there is interest in testing it in antitumor therapy. We show here that PO treatment for 1 week induced positive pathological changes in 6 out of 20 patients with breast cancer, including complete response in a triple-negative patient. This correlated with an increased tumor CD4⁺ T-lymphocyte infiltration. The immune effects of PO are associated with myeloid cell activation, and little is known about the action of PO on lymphocyte lineages, such as natural killer (NK) and T cells. We reveal that PO increases T-cell proliferation in vitro without negative effects on any activation marker. PO does not affect dendritic cell (DC) viability and increases the expansion of immature DC (iDC) and mature DC (mDC) at 100 μg/ml, and it stimulates expression of several DC co-stimulatory molecules, inducing the proliferation of allogeneic T cells. In contrast, PO decreases DC viability when added at day 5 post-expansion. PO is not toxic for NK cells at doses up to 100 μM and does not affect their activation, maturation, and cytotoxicity but tends to increase degranulation. This could be beneficial against target cells that show low sensitivity to NK cells, e.g., solid tumor cells. Finally, we have found great variability in PO response between donors. In summary, our in vitro results show that PO increases the number of costimulatory molecules on DC that prime T cells, favoring the production of effector T cells. This may support the future clinical development of PO in cancer treatment.

NK Cells in the Treatment of Hematological Malignancies

Natural killer (NK) cells have the innate ability to kill cancer cells, however, tumor cells may acquire the capability of evading the immune response, thereby leading to malignancies. Restoring or potentiation of this natural antitumor activity of NK cells has become a relevant therapeutic approach in cancer and, particularly, in hematological cancers. The use of tumor-specific antibodies that promote antibody-dependent cell-mediated cytotoxicity (ADCC) through the ligation of CD16 receptor on NK cells has become standard for many hematologic malignancies. Hematopoietic stem cell transplantation is another key therapeutic strategy that harnesses the alloreactivity of NK cells against cancer cells. This strategy may be refined by adoptive transfer of NK cells that may be previously expanded, activated, or redirected (chimeric antigen receptor (CAR)-NK cells) against cancer cells. The antitumor activity of NK cells can also be boosted by cytokines or immunostimulatory drugs such as lenalidomide or pomalidomide. Finally, targeting immunosubversive mechanisms developed by hematological cancers and, in particular, using antibodies that block NK cell inhibitory receptors and checkpoint proteins are novel promising therapeutic approaches in these malignant diseases.

Obinutuzumab combined with lenalidomide for relapsed or refractory follicular B-cell lymphoma (GALEN): a multicentre, single-arm, phase 2 study

BACKGROUND

Lenalidomide plus rituximab is approved to treat patients with relapsed or refractory follicular lymphoma. Obinutuzumab has been shown to enhance antibody-dependent cellular cytotoxicity, phagocytosis, and direct B-cell killing better than rituximab. Our aim was to determine the activity and safety of lenalidomide plus obinutuzumab in previously treated patients with relapsed or refractory follicular lymphoma.

METHODS

In this multicentre, single-arm, phase 2 study, patients were enrolled from 24 Lymphoma Academic Research Organisation centres in France. Eligible patients (age ≥18 years) had histologically confirmed CD20-positive relapsed or refractory follicular lymphoma of WHO grade 1, 2, or 3a; an ECOG performance status of 0-2; and received at least one previous rituximab-containing therapy. Patients received oral lenalidomide (20 mg) plus intravenously infused obinutuzumab as induction therapy (1000 mg; six 28-day cycles), 1-year maintenance with lenalidomide (10 mg; 12 28-day cycles; days 2-22) plus obinutuzumab (1000 mg; alternate cycles), and 1-year maintenance with obinutuzumab (1000 mg; six 56-day cycles; day 1). The primary endpoint was the proportion of patients who achieved an overall response at induction end as per investigator assessment using the 1999 international working group criteria. The secondary endpoints were event-free survival, progression-free survival, overall survival, and safety. Analyses were per-protocol; the efficacy population included all patients who received at least one dose of both obinutuzumab and lenalidomide, and the safety population included all patients who received one dose of either investigational drug. The study is registered with ClinicalTrials.gov, number NCT01582776, and is ongoing but closed to accrual.

FINDINGS

Between June 11, 2014, and Dec 18, 2015, 89 patients were recruited and 86 patients were evaluable for efficacy and 88 for safety. Median follow-up was 2·6 years (IQR 2·2-2·8). 68 (79%) of 86 evaluable patients (95% CI 69-87) achieved an overall response at induction end, meeting the prespecified primary endpoint. At 2 years, event-free survival was 62% (95% CI 51-72), progression-free survival 65% (95% CI 54-74), duration of response 70% (95% CI 57-79), and overall survival 87% (95% CI 78-93). Complete response was achieved by 33 (38%, 95% CI 28-50) of 86 patients at induction end, and the proportion of patients achieving a best overall response was 70 (81%, 95% CI 72-89) and 72 (84%, 74-91) of 86 patients during induction and treatment, respectively. The most common adverse events were asthenia (n=54, 61%), neutropenia (n=38, 43%), bronchitis (n=36, 41%), diarrhoea (n=35, 40%), and muscle spasms (n=34, 39%). Neutropenia was the most common toxicity of grade 3 or more; four (5%) patients had febrile neutropenia. 57 serious adverse events were reported in 30 (34%) of 88 patients. The most common serious adverse events were basal cell carcinoma (n=5, 6%), febrile neutropenia (n=4, 5%), and infusion-related reaction (n=3, 3%). One patient died due to treatment-related febrile neutropenia.

INTERPRETATION

Our data shows that lenalidomide plus obinutuzumab is active in previously treated patients with relapsed or refractory follicular lymphoma, including those with early relapse, and has a manageable safety profile. Randomised trials of new immunomodulatory regimens, such as GALEN or using GALEN as a backbone, versus lenalidomide plus rituximab, are warranted.

FUNDING

Lymphoma Academic Research Organisation, and Celgene and Roche.

Development and validation of an interferon signature predicting prognosis and treatment response for glioblastoma

Background: Interferon treatment, as an important approach of anti-tumor immunotherapy, has been implemented in multiple clinical trials of glioma. However, only a small number of gliomas benefit from it. Therefore, it is necessary to investigate the clinical role of interferons and to establish robust biomarkers to facilitate its application. Materials and methods: This study reviewed 1,241 glioblastoma (GBM) and 1,068 lower grade glioma (LGG) patients from six glioma cohorts. The transcription matrix and clinical information were analyzed using R software, GraphPad Prism 7 and Medcalc, etc. Immunohistochemical (IHC) staining were performed for validation in protein level. Results: Interferon signaling was significantly enhanced in GBM. An interferon signature was developed based on five interferon genes with prognostic significance, which could reflect various interferon statuses. Survival analysis showed the signature could serve as an unfavorable prognostic factor independently. We also established a nomogram model integrating the risk signature into traditional prognostic factors, which increased the validity of survival prediction. Moreover, high-risk group conferred resistance to chemotherapy and high IFNB1 expression levels. Functional analysis showed that the high-risk group was associated with overloaded immune response. Microenvironment analysis and IHC staining found that high-risk group occupied a disorganized microenvironment which was characterized by an enrichment of M0 macrophages and neutrophils, but less infiltration of activated nature killing (NK) cells and M1 type macrophages. Conclusion: This interferon signature was an independent indicator for unfavorable prognosis and showed great potential for screening out patients who will benefit from chemotherapy and interferon treatment.

Combination lenalidomide-rituximab immunotherapy activates anti-tumour immunity and induces tumour cell death by complementary mechanisms of action in follicular lymphoma

Chemotherapy plus rituximab has been the mainstay of treatment for follicular lymphoma (FL) for two decades but is associated with immunosuppression and relapse. In phase 2 studies, lenalidomide combined with rituximab (R²) has shown clinical synergy in front‐line and relapsed/refractory FL. Here, we show that lenalidomide reactivated dysfunctional T and Natural Killer (NK) cells ex vivo from FL patients by enhancing proliferative capacity and T‐helper cell type 1 (Th1) cytokine release. In combination with rituximab, lenalidomide improved antibody‐dependent cellular cytotoxicity in sensitive and chemo‐resistant FL cells, via a cereblon‐dependent mechanism. While single‐agent lenalidomide and rituximab increased formation of lytic NK cell immunological synapses with primary FL tumour cells, the combination was superior and correlated with enhanced cytotoxicity. Immunophenotyping of FL patient samples from a phase 3 trial revealed that R² treatment increased circulating T‐ and NK‐cell counts, while R‐chemotherapy was associated with reduced cell numbers. Finally, using an in vitro model of myeloid differentiation, we demonstrated that lenalidomide caused a reversible arrest in neutrophil maturation that was distinct from a cytotoxic chemotherapeutic agent, which may help explain the lower rates of neutropenia observed with R²versus R‐chemotherapy. Taken together, we believe these data support a paradigm shift in the treatment of FL – moving from combination immunochemotherapy to chemotherapy‐free immunotherapy.

Trial Watch: Toll-like receptor agonists in cancer immunotherapy

Toll-like receptor (TLR) agonists demonstrate therapeutic promise as immunological adjuvants for anticancer immunotherapy. To date, three TLR agonists have been approved by US regulatory agencies for use in cancer patients. Additionally, the potential of hitherto experimental TLR ligands to mediate clinically useful immunostimulatory effects has been extensively investigated over the past few years. Here, we summarize recent preclinical and clinical advances in the development of TLR agonists for cancer therapy.

An open-label phase 1b study of obinutuzumab plus lenalidomide in relapsed/refractory follicular B-cell lymphoma

Obinutuzumab is a type II anti-CD20 monoclonal antibody that enhances antibody-dependent cellular cytotoxicity better than rituximab. Given promising results with lenalidomide and rituximab, this phase 1b study assessed the safety and efficacy of lenalidomide combined with obinutuzumab (GALEN). Patients age ≥18 years with relapsed or refractory (R/R) follicular lymphoma (FL) after rituximab-containing therapy received escalating doses (10 [n = 7], 15 [n = 3], 20 [n = 6], and 25 mg [n = 3]) of daily oral lenalidomide on days 1 to 21 of cycle 1 and on days 2 to 22 of cycles 2 to 6 (28-day cycles). Obinutuzumab 1000 mg IV was administered on days 8, 15, and 22 (cycle 1) and on day 1 (cycles 2-6). Dose was escalated in a 3 + 3 design based on dose-limiting toxicity (DLT) during cycle 1 to establish the maximum tolerated dose (MTD). We observed 164 adverse events (AEs), of which 139 were grade 1/2. The most common AEs were constipation (52.6%), neutropenia (47.4%), and asthenia (36.8%); 64.3% (9 of 14) of the grade 3/4 AEs were neutropenia/neutrophil decrease, but without any febrile neutropenia. Four DLTs occurred in 2 patients, all deemed unrelated to treatment. MTD was not reached. Twelve patients (63.2%) responded: 8 complete, 3 unconfirmed complete, and 1 partial response. Oral lenalidomide plus obinutuzumab is well tolerated and effective in R/R FL. The recommended dose of lenalidomide was established at 20 mg based on the risk of grade 3/4 neutropenia from cycle 2. This trial was registered at www.clinicaltrials.gov as #NCT01582776.

Expansion of allogeneic NK cells with efficient antibody-dependent cell cytotoxicity against multiple tumors

Monoclonal antibodies (mAbs) have significantly improved the treatment of certain cancers. However, in general mAbs alone have limited therapeutic activity. One of their main mechanisms of action is to induce antibody-dependent cell-mediated cytotoxicity (ADCC), which is mediated by natural killer (NK) cells. Unfortunately, most cancer patients have severe immune dysfunctions affecting NK activity. This can be circumvented by the injection of allogeneic, expanded NK cells, which is safe. Nevertheless, despite their strong cytolytic potential against different tumors, clinical results have been poor.

Methods: We combined allogeneic NK cells and mAbs to improve cancer treatment. We generated expanded NK cells (e-NK) with strong in vitro and in vivo ADCC responses against different tumors and using different therapeutic mAbs, namely rituximab, obinutuzumab, daratumumab, cetuximab and trastuzumab.

Results: Remarkably, e-NK cells can be stored frozen and, after thawing, armed with mAbs. They mediate ADCC through degranulation-dependent and -independent mechanisms. Furthermore, they overcome certain anti-apoptotic mechanisms found in leukemic cells.

Conclusion: We have established a new protocol for activation/expansion of NK cells with high ADCC activity. The use of mAbs in combination with e-NK cells could potentially improve cancer treatment.