NK cells with adhesion defects and reduced cytotoxic functions are associated with a poor prognosis in Multiple Myeloma.

The promising results obtained with immunotherapeutic approaches for multiple myeloma (MM) call for a better stratification of patients based on immune components. The most pressing being cytotoxic lymphocytes such as Natural Killer (NK) cells that are mandatory for MM surveillance and therapy. In this study, we performed a single cell RNA sequencing analysis of NK cells from 10 MM patients and 10 age/sex matched healthy donors (HD) that revealed important transcriptomic changes in NK cell landscape affecting both the bone marrow and peripheral blood compartment. The frequency of mature cytotoxic "CD56dim" NK cell subsets was reduced in MM patients at the advantage of late-stage NK cell subsets expressing NFB and IFN-I inflammatory signatures. These NK cell subsets accumulating in MM patients were characterized by a low CD16 and CD226 expression and poor cytotoxic functions. MM CD16/CD226Lo NK cells also had adhesion defects with reduced LFA-1 integrin activation and actin polymerization that may account for their limited effector functions in vitro. Finally, analysis of BM infiltrating NK cells in a retrospective cohort of 177 MM patients from the IFM 2009 trial demonstrated that a high frequency of NK cells and their low CD16 and CD226 expression were associated with a shorter overall survival. Thus, CD16/CD226Lo NK cells with reduced effector functions accumulate along MM development and negatively impact patients' clinical outcome. Given the growing interest in harnessing NK cells to treat myeloma, this improved knowledge around MM-associated NK cell dysfunction will stimulate the development of more efficient immunotherapeutic drugs against MM.

Bortezomib, thalidomide, and dexamethasone with or without daratumumab and followed by daratumumab maintenance or observation in transplant-eligible newly diagnosed multiple myeloma: long-term follow-up of the CASSIOPEIA randomised controlled phase 3 trial.

BACKGROUND: CASSIOPEIA part 1 demonstrated superior depth of response and prolonged progression-free survival with daratumumab in combination with bortezomib, thalidomide, and dexamethasone (D-VTd) versus bortezomib, thalidomide, and dexamethasone (VTd) alone as an induction and consolidation regimen in transplant-eligible patients newly diagnosed with myeloma. In CASSIOPEIA part 2, daratumumab maintenance significantly improved progression-free survival and increased minimal residual disease (MRD)-negativity rates versus observation. Here, we report long-term study outcomes of CASSIOPEIA. METHODS: CASSIOPEIA was a two-part, open-label, phase 3 trial of patients done at 111 European academic and community-based centres. Eligible patients were aged 18-65 years with transplant-eligible newly diagnosed myeloma and an Eastern Cooperative Oncology Group performance status of 0-2. In part 1, patients were randomly assigned (1:1) to pre-transplant induction and post-transplant consolidation with D-VTd or VTd. Patients who completed consolidation and had a partial response or better were re-randomised (1:1) to intravenous daratumumab maintenance (16 mg/kg every 8 weeks) or observation for 2 years or less. An interactive web-based system was used for both randomisations, and randomisation was balanced using permuted blocks of four. Stratification factors for the first randomisation (induction and consolidation phase) were site affiliation, International Staging System disease stage, and cytogenetic risk status. Stratification factors for the second randomisation (maintenance phase) were induction treatment and depth of response in the induction and consolidation phase. The primary endpoint for the induction and consolidation phase was the proportion of patients who achieved a stringent complete response after consolidation; results for this endpoint remain unchanged from those reported previously. The primary endpoint for the maintenance phase was progression-free survival from second randomisation. Efficacy evaluations in the induction and consolidation phase were done on the intention-to-treat population, which included all patients who underwent first randomisation, and efficacy analyses in the maintenance phase were done in the maintenance-specific intention-to-treat population, which included all patients who were randomly assigned at the second randomisation. This analysis represents the final data cutoff at the end of the study. The trial is registered with ClinicalTrials.gov, NCT02541383. FINDINGS: Between Sept 22, 2015 and Aug 1, 2017, 1085 patients were randomly assigned to D-VTd (n=543) or VTd (n=542); between May 30, 2016 and June 18, 2018, 886 were re-randomised to daratumumab maintenance (n=442) or observation (n=444). At the clinical cutoff date, Sept 1, 2023, median follow-up was 80·1 months (IQR 75·7-85·6) from first randomisation and 70·6 months (66·4-76·1) from second randomisation. Progression-free survival from second randomisation was significantly longer in the daratumumab maintenance group than the observation-alone group (median not reached [95% CI 79·9-not estimable (NE)] vs 45·8 months [41·8-49·6]; HR 0·49 [95% CI 0·40-0·59]; p<0·0001); benefit was observed with D-VTd with daratumumab maintenance versus D-VTd with observation (median not reached [74·6-NE] vs 72·1 months [52·8-NE]; 0·76 [0·58-1·00]; p=0·048) and VTd with daratumumab maintenance versus VTd with observation (median not reached [66·9-NE] vs 32·7 months [27·2-38·7]; 0·34 [0·26-0·44]; p<0·0001). INTERPRETATION: The long-term follow-up results of CASSIOPEIA show that including daratumumab in both the induction and consolidation phase and the maintenance phase led to superior progression-free survival outcomes. Our results confirm D-VTd induction and consolidation as a standard of care, and support the option of subsequent daratumumab monotherapy maintenance, for transplant-eligible patients with newly diagnosed multiple myeloma. FUNDING: Intergroupe Francophone du Myélome, Dutch-Belgian Cooperative Trial Group for Hematology Oncology, and Janssen Research & Development.

Bone marrow stromal cells induce chromatin remodeling in multiple myeloma cells leading to transcriptional changes.

The natural history of multiple myeloma is characterized by its localization to the bone marrow and its interaction with bone marrow stromal cells. The bone marrow stromal cells provide growth and survival signals, thereby promoting the development of drug resistance. Here, we show that the interaction between bone marrow stromal cells and myeloma cells (using human cell lines) induces chromatin remodeling of cis-regulatory elements and is associated with changes in the expression of genes involved in the cell migration and cytokine signaling. The expression of genes involved in these stromal interactions are observed in extramedullary disease in patients with myeloma and provides the rationale for survival of myeloma cells outside of the bone marrow microenvironment. Expression of these stromal interaction genes is also observed in a subset of patients with newly diagnosed myeloma and are akin to the transcriptional program of extramedullary disease. The presence of such adverse stromal interactions in newly diagnosed myeloma is associated with accelerated disease dissemination, predicts the early development of therapeutic resistance, and is of independent prognostic significance. These stromal cell induced transcriptomic and epigenomic changes both predict long-term outcomes and identify therapeutic targets in the tumor microenvironment for the development of novel therapeutic approaches.

Twice-weekly induction with ixazomib-lenalidomide-dexamethasone (IRd) combination followed by extended IRd consolidation and lenalidomide maintenance in transplant-eligible patients with newly diagnosed multiple myeloma: Results of the phase 2 study IFM2014-03.

Therapeutic strategies for patients with newly diagnosed multiple myeloma (NDMM) have considerably improved during the last 10 years. The IFM2014-03 trial proposed an all-oral triplet induction/consolidation regimen in transplant-eligible NDMM patients, followed by lenalidomide maintenance. Induction consisted of three 21-day cycles of ixazomib, lenalidomide and dexamethasone (IRd), before high-dose Melphalan with transplant followed by eight 28-day cycles of IRd consolidation before 13 cycles of lenalidomide maintenance. Forty-six patients were enrolled and received at least one dose of therapy, and 39 entered the maintenance phase. The primary end-point was stringent complete response after consolidation, and was achieved in nine patients (20.9%, 90% CI 11.4-33.7; p = 0.998). Ten patients (24.4%) had an undetectable minimal residual disease. The overall response rate was 95.7%. The 3-year progression-free survival was 66.3%. No unexpected toxicities were recorded, and only eight patients suspended from any study drug. Of note, 21 (45.7%) patients reported peripheral neuropathy (PN) (grades 1-2 with no serious adverse events). IRd induction and consolidation with transplant before lenalidomide maintenance shows lower response rates compared to other triplet therapies. It could be an alternative for patients who require an all-oral regimen and/or with pre-existent PN, especially if quadruplet regimens including anti-CD38 antibody are not available.

RAS/RAF landscape in monoclonal plasma cell conditions.

ABSTRACT: Multiple myeloma is characterized by a huge heterogeneity at the molecular level. The RAS/RAF pathway is the most frequently mutated, in ∼50% of the patients. However, these mutations are frequently subclonal, suggesting a secondary event. Because these genes are part of our routine next-generation sequencing panel, we analyzed >10 000 patients with different plasma cell disorders to describe the RAS/RAF landscape. In this large cohort of patients, almost 61% of the patients presented a RAS/RAF mutation at diagnosis or relapse, but much lower frequencies occurred in presymptomatic cases. Of note, the mutations were different from that observed in solid tumors (higher proportions of Q61 mutations). In 29 patients with 2 different mutations, we were able to perform single-cell sequencing, showing that in most cases, mutations occurred in different subclones, suggesting an ongoing mutational process. These findings suggest that the RAS/RAF pathway is not an attractive target, both on therapeutic and residual disease assessment points of view.

Early Chimeric Antigen Receptor T Cell Expansion Is Associated with Prolonged Progression-Free Survival for Patients with Relapsed/Refractory Multiple Myeloma Treated with Ide-Cel: A Retrospective Monocentric Study.

The outcomes of patients with relapsed and refractory multiple myeloma (RRMM) previously treated with the 3 main classes of myeloma therapy-immunomodulatory drugs, proteasome inhibitors, and anti-CD38 antibodies-remain poor. Recently, based on the phase II pivotal KarMMa trial showing prolonged overall survival (OS) and progression-free survival (PFS) in heavily treated patients, idecabtagene vicleucel (ide-cel), a B cell maturation antigen (BCMA)-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) product, was approved in the United States for the treatment of RRMM. In France, since June 2021, an early access program has authorized the use of ide-cel in the setting of RRMM (defined as progressive myeloma after at least 3 previous regimens, including the 3 main antimyeloma therapies). We report the first French experience through this early access program in a retrospective study of 24 consecutive patients treated with ide-cel at our institution. The patients were evaluated according to International Myeloma Working Group criteria and by positron emission tomography computed tomography (PET-CT) at 1, 3, 6, 9, and 12 months after ide-cel infusion. Most patients had adverse cytogenetic abnormalities, and RRMM with triple-refractory drugs were seen in 79%. Bridging therapy was required for 19 of 24 patients. Before CAR-T cell infusion, lymphodepletion with fludarabine and cyclophosphamide was systematically performed. The median follow-up was 15.2 months. At 3 months after ide-cel infusion, 92% of patients achieved at least a partial response, and 50% achieved a complete response or better (≥CR). At 6 months, 70% of patients had a persistent ≥CR. At 3 and 6 months, bone marrow minimal residual disease (10-6 level) was undetectable in 79% and 75% of patients, respectively. At 6 months, CR as assessed by PET-CT was achieved in 15 of 20 patients (75%). The median PFS was 14.8 months, and median OS was not reached. Notably, an expansion of circulating CAR-T cells to >180/mm3 after infusion was strongly associated with prolonged PFS. Additionally, the level of soluble BCMA measured before infusion was identified as a prognostic factor for PFS, likely correlated to the tumor burden. Grade 1-2 cytokine release syndrome (CRS) occurred in 22 of 24 patients (92%). Only 1 patient (4%) experienced grade ≥3 CRS. The occurrence of neurologic toxicity was infrequent (12.5%) and reversible in all cases. Hematologic toxicity was relatively common, and secondary hypogammaglobulinemia occurred in most patients. Infections (mostly viral) were frequent but most often nonsevere. This study echoes the promising results of the KarMMa trial and identifies possible prognostic indicators in RRMM patients treated with ide-cel, potentially refining treatment strategies and improving outcomes in this challenging context.

Smoldering multiple myeloma: taking the narrow over the wide path?

ABSTRACT: Smoldering multiple myeloma (MM) is an asymptomatic clonal plasma cell condition considered as a premalignant entity that may evolve over time to symptomatic MM. Based on a "poorly defined" risk of progression, some well-intended investigators proposed prospective interventional trials for these individuals. We believe this may be a harmful intervention and favor a close "wait and watch" approach and rather enroll these patients in dedicated observational biological studies aiming to better identify patients who will evolve to MM, based on their plasma cells' biology, including genomics, epigenetics, and the immune microenvironment.

Daratumumab, carfilzomib, lenalidomide, and dexamethasone with tandem transplant for high-risk newly diagnosed myeloma.

ABSTRACT: High-risk (HR) cytogenetics are associated with poor outcomes in newly diagnosed multiple myeloma (NDMM), and dedicated studies should address this difficult-to-treat population. The phase 2 study 2018-04 from the Intergroupe Francophone du Myelome evaluated feasibility of an intensive strategy with quadruplet induction and consolidation plus tandem transplant in HR transplant-eligible (TE) NDMM. HR cytogenetics were defined by presence of del(17p), t(4;14), and/or t(14;16). Treatment consisted of daratumumab-carfilzomib-lenalidomide-dexamethasone (D-KRd) induction, autologous stem cell transplantation (ASCT), D-KRd consolidation, second ASCT, and daratumumab-lenalidomide maintenance. The primary end point was feasibility. Fifty patients with previously untreated NDMM were included. Median age was 57. Del(17p), t(4;14), and t(14;16) were found in 40%, 52%, and 20% of patients, respectively. At data cutoff, the study met the primary end point with 36 patients completing second transplant. Twenty patients discontinued the study due to stem cell collection failure (n = 8), disease progression (n = 7), adverse event (n = 4), or consent withdrawal (n = 1). Grade 3 to 4 D-KRd induction/consolidation-related adverse events (>5% of patients) were neutropenia (39%), anemia (12%), thrombocytopenia (7%), and infection (6%). The overall response rate was 100% for patients completing second transplant, including 81% complete response. Premaintenance minimal residual disease (MRD) negativity rate (10-6) was 94%. After a median follow-up of 33 months, the 30-month progression-free survival (PFS) and overall survival were 80% and 91%, respectively. In conclusion, D-KRd with tandem transplant is feasible in patients with HR TE-NDMM and resulted in high response rates and PFS. This trial was registered at www.clinicaltrials.gov as #NCT03606577.

Venous thromboembolism prophylaxis and multiple myeloma patients in real-life: Results of a large survey and clinical guidance recommendations from the IFM group.

Venous thromboembolism (VTE) remains a critical issue in the management of patients with multiple myeloma (MM), particularly when immunomodulatory drugs (IMiDs) combined with dexamethasone therapy are being prescribed as first-line and relapse therapy. One possible explanation for the persistent high rates of VTE, is the use of inappropriate thromboprophylaxis strategies for patients starting antimyeloma treatment. To tackle the issue, the Intergroupe francophone du myélome (IFM) offered convenient guidance for VTE thromboprophylaxis in MM patients initiating systemic therapy. This guidance is mainly supported by the results of a large survey on the clinical habits regarding VTE of physicians who are substantially involved in daily care of MM patients. VTE prophylaxis should be considered for all patients treated with IMiDs in combination with dexamethasone, in the absence of significant comorbidities, such as renal failure or bleeding risk. Anticoagulant should be preferred to antiplatelet agents for thromboprophylaxis. Despite the absence of large randomized controlled trials comparing those attitudes/options, available data on direct oral anticoagulants, which are already used in daily management of MM patients, are consistent with their potential usefulness for VTE prophylaxis in such patients. However, in order to implement a personalized continuous improvement strategy, clinicians must to be organized to collect all the data regarding this management. In other situations, thromboprophylaxis should be evaluated by using risk models and after careful evaluation of the risk/benefit ratio.

Immunomodulation of NK, NKT and B/T cell subtypes in relapsed/refractory multiple myeloma patients treated with pomalidomide along with velcade and dexamethasone and its association with improved progression-free survival.

Background: Multiple Myeloma (MM) patients exhibit dysregulated immune system, which is further weakened by chemotherapeutic agents. While cereblon-modulating agents, such as pomalidomide and lenalidomide, have been found to improve the immune profile, the efficacy of their impact in combination with other treatments is yet unknown. Methods: We conducted an immune-profiling of a longitudinal cohort of 366 peripheral blood samples from the CC4047-MM-007 (OPTIMISMM, NCT01734928) study. This study followed relapsed/refractory Multiple Myeloma (RRMM) patients who were treated with Velcade + dexamethasone (Vd), or Vd with pomalidomide (PVd). 366 blood samples from 186 patients were evaluated using multi-color flow cytometry at 3 timepoints: screening, day 8 of cycle 1, and cycle 3. Results: Among NK and NKT cell populations, adding pomalidomide showed no inhibition in the frequency of NK cells. When expression of double positivity for activation markers like, p46/NKG2D, on NK cells was higher than the median, PVd treated patients showed significantly better (p=0.05) progression-free survival (PFS) (additional 15 months) than patients with lower than the median expression of p46/NKG2D on NK cells. PVd treated patients who expressed CD158a/b below the median at cycle 1 demonstrated a significantly better PFS (more than 18months). Among B cell subtypes, PVd treatment significantly increased the abundance of B1b cells (p<0.05) and decreased Bregs (p<0.05) at day 8 of both cycle 1 and cycle 3 when compared to screening samples. Of all the B cell-markers evaluated among paired samples, a higher expression of MZB cells at day 8 of cycle 1 has resulted in enhanced PFS in PVd treated patients. Within T cells, pomalidomide treatment did not decrease the frequency of CD8 T cells when compared with screening samples. The higher the surface expression of OX-40 on CD8 T cells and the lower the expression of PD-1 and CD25 on CD4 T cells by PVd treatment resulted in improved PFS. Conclusion: The prognostic significance for the number of immune markers is only seen in the PVd arm and none of these immune markers exhibit prognostic values in the Vd arm. This study demonstrates the importance of the immunomodulatory effects and the therapeutic benefit of adding pomalidomide to Vd treatment.

t(11;14) status is stable between diagnosis and relapse, and concordant between detection methodologies based on fluorescence in situ hybridization and next-generation sequencing in patients with multiple myeloma.

Multiple myeloma (MM) is associated with a wide variety of recurrent genomic alterations. The most common translocation in MM is t(11;14). In this retrospective, single-center, non-interventional study, patient bone marrow samples were examined at diagnosis and at relapse(s) following treatment with anti-myeloma regimens to determine whether t(11;14) status was stable over time. This Stability Cohort consisted of 272 patients, of whom 118 were t(11;14)-positive at diagnosis and 154 were negative. All patients in the Stability Cohort retained the same t(11;14) status at relapse that they had at diagnosis of MM. Sixteen patients who had t(11;14)-positive MM at diagnosis had multiple longitudinal FISH assessments at relapse events, which remained t(11;14)-positive across all time points. Patients who had t(11;14)-positive disease at diagnosis of monoclonal gammopathy of unknown significance (MGUS) or smoldering multiple myeloma (SMM) also retained t(11;14) positivity through MM diagnosis and relapse. The t(11;14) fusion patterns also remained constant for 90% of patients. For detection of t(11;14), results from fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) were compared to determine the rate of concordance between these 2 methods. This Concordance Cohort contained 130 patients, of whom 66 had t(11;14)-positive disease and 64 were t(11;14)-negative. In this sample set, the concordance between FISH and NGS-based detection of t(11;14) was 100%. These results strongly suggest that the t(11;14) rearrangement remains stable during the full disease course in patients with multiple myeloma and can be detected by FISH- and NGS-based methodologies.

Large T cell clones expressing immune checkpoints increase during multiple myeloma evolution and predict treatment resistance.

Tumor recognition by T cells is essential for antitumor immunity. A comprehensive characterization of T cell diversity may be key to understanding the success of immunomodulatory drugs and failure of PD-1 blockade in tumors such as multiple myeloma (MM). Here, we use single-cell RNA and T cell receptor sequencing to characterize bone marrow T cells from healthy adults (n = 4) and patients with precursor (n = 8) and full-blown MM (n = 10). Large T cell clones from patients with MM expressed multiple immune checkpoints, suggesting a potentially dysfunctional phenotype. Dual targeting of PD-1 + LAG3 or PD-1 + TIGIT partially restored their function in mice with MM. We identify phenotypic hallmarks of large intratumoral T cell clones, and demonstrate that the CD27- and CD27+ T cell ratio, measured by flow cytometry, may serve as a surrogate of clonal T cell expansions and an independent prognostic factor in 543 patients with MM treated with lenalidomide-based treatment combinations.

Measurable Residual Disease Testing in Multiple Myeloma Routine Clinical Practice: A Modified Delphi Study.

We used a modified Delphi approach to establish areas of consensus and nonconsensus regarding the utility of determining measurable residual disease (MRD) to assess multiple myeloma (MM) treatment response, which may inform disease management and design of future clinical trials. This modified Delphi study incorporated 2 iterative rounds of surveys to evaluate the opinions of an expert panel of 61 practicing hematological oncologists from across 14 countries in Europe concerning the use of MRD testing in MM management. Survey 1 assessed experts' opinions on MRD testing in different clinical situations and associated challenges. Survey 2 focused on the lack of consensus areas identified in survey 1. Consensus to an individual question was defined a priori as 75% agreement or disagreement by the panel. From the 2 rounds of surveys, the experts reached consensus agreement that MRD testing should be performed in newly diagnosed or relapsed patients who achieved complete response (CR) or better after transplantation. In transplant-ineligible patients, experts recommended MRD testing in those who are ≤70 years old and in CR. If a patient was previously positive on positron-emission tomography and computed tomography (PET/CT), both MRD and PET/CT should be assessed at CR. MRD testing should be performed ≤6 months after transplantation and every 6-12 months in continuously treated patients in CR. There was no consensus on making treatment decisions based on MRD status. MRD testing is an important component of clinical management in MM. Additional data will further clarify the role of MRD in guiding treatment decisions.

Deneddylation of ribosomal proteins promotes synergy between MLN4924 and chemotherapy to elicit complete therapeutic responses.

The neddylation inhibitor MLN4924/Pevonedistat is in clinical trials for multiple cancers. Efficacy is generally attributed to cullin RING ligase (CRL) inhibition, but the contribution of non-CRL targets is unknown. Here, CRISPR screens map MLN4924-monotherapy sensitivity in retinoblastoma to a classic DNA damage-induced p53/E2F3/BAX-dependent death effector network, which synergizes with Nutlin3a or Navitoclax. In monotherapy-resistant cells, MLN4924 plus standard-of-care topotecan overcomes resistance, but reduces DNA damage, instead harnessing ribosomal protein nucleolar-expulsion to engage an RPL11/p21/MYCN/E2F3/p53/BAX synergy network that exhibits extensive cross-regulation. Strikingly, unneddylatable RPL11 substitutes for MLN4924 to perturb nucleolar function and enhance topotecan efficacy. Orthotopic tumors exhibit complete responses while preserving visual function. Moreover, MLN4924 plus melphalan deploy this DNA damage-independent strategy to synergistically kill multiple myeloma cells. Thus, MLN4924 synergizes with standard-of-care drugs to unlock a nucleolar death effector network across cancer types implying broad therapeutic relevance.

Potential future direction of measurable residual disease evaluation in multiple myeloma.

Multiple myeloma remains an incurable disease plagued by high relapse rates. Deeper and more sustainable responses, however, have been consistently shown to improve outcomes and could eventually pave the way to achieving a cure. Our understanding of disease response has surpassed complete response (CR), because the current definitions are suboptimal, and the treatment goal should aim even beyond stringent CR, toward molecular and flow CR, that is, measurable residual disease (MRD) negativity. It has been more than 20 years since the discrepancy in the outcome between patients in CR with and without MRD has been demonstrated, and the field has come a long way from multiparameter flow cytometry to next-generation flow and next-generation sequencing, able to detect up to a limit of detection of a single myeloma cell from 1 million healthy counterparts. This review aims to summarize the current available data regarding MRD but also its potential future use as a coprimary outcome both in clinical and trial settings as a survival surrogate as well as its use to evaluate treatment efficacy and for adaptive response-based and early-rescue therapy. Furthermore, we discuss whether these concepts are applicable in different settings (eg, newly diagnosed and relapsed/refractory myeloma, patients who are eligible and ineligible for tansplant, and standard- and high-risk disease).

TCR-independent CD137 (4-1BB) signaling promotes CD8+-exhausted T cell proliferation and terminal differentiation.

CD137 (4-1BB)-activating receptor represents a promising cancer immunotherapeutic target. Yet, the cellular program driven by CD137 and its role in cancer immune surveillance remain unresolved. Using T cell-specific deletion and agonist antibodies, we found that CD137 modulates tumor infiltration of CD8+-exhausted T (Tex) cells expressing PD1, Lag-3, and Tim-3 inhibitory receptors. T cell-intrinsic, TCR-independent CD137 signaling stimulated the proliferation and the terminal differentiation of Tex precursor cells through a mechanism involving the RelA and cRel canonical NF-κB subunits and Tox-dependent chromatin remodeling. While Tex cell accumulation induced by prophylactic CD137 agonists favored tumor growth, anti-PD1 efficacy was improved with subsequent CD137 stimulation in pre-clinical mouse models. Better understanding of T cell exhaustion has crucial implications for the treatment of cancer and infectious diseases. Our results identify CD137 as a critical regulator of Tex cell expansion and differentiation that holds potential for broad therapeutic applications.