Aggressive B-cell non-Hodgkin Lymphoma Research Articles

EFFICACY OF FRONT‐LINE IMMUNOCHEMOTHERAPY FOR TRANSPLANT‐INELIGIBLE MANTLE CELL LYMPHOMA: A NETWORK META‐ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

Background: In the past 20 years, there have been significant advances in the prognosis of mantle cell lymphoma (MCL) patients because of the introduction of rituximab. However, there is still no cure, and the relapse is inevitable. The earlier MCL patients progress after the first-line therapy, the worse the prognosis, especially for those who progress within 6 months after first-line therapy. There is no standard first-line immunochemotherapy regimen for transplant-ineligible patients with MCL currently, and the efficacy of various treatment remains unclear. Methods: Network meta-analysis (NMA) can compare the relative treatment effects of multiple interventions by synthesizing evidence from a network of randomized controlled trials (RCTs), which can be very useful for the choice of clinical treatment plans. We conducted a Bayesian NMA of all eligible randomized controlled trials. Pairwise comparisons and ranking of different first-line treatment options were performed. Results: nine studies were included in the NMA, involving a total of 2,897 MCL patients. The BR-Ibrutinib+R regimen showed the best progression-free survival (PFS), with a surface under the cumulative ranking curve (SUCRA) of 0.89 (Figure 1a) and probability of being the best treatment (PbBT) of 69%, followed by the BR+R regimen (SUCRA 0.76, PbBT 11%) and the BVR regimen (SUCRA 0.64, PbBT 13%). The VR-CAP regimen was the most potential intervention to improve overall survival (OS), with a SUCRA of 0.89 (Figure 1b) and PbBT of 63%, followed by the BR regimen (SUCRA 0.74, PbBT 22%) and the R-CHOP regimen (SUCRA 0.65, PbBT 1%). Compared with the R-CHOP regimen, the BR regimen achieved a better PFS (hazard ratio [HR] 0.45 [95% credible interval 0.2–0.96]). The BR-Ibrutinib+R regimen (HR 0.14 [0.02–0.99]), BR+R regimen (HR 0.19 [0.034–0.99]), and BR regimen (HR 0.19 [0.08–1.03]) were superior to CHOP regimen with better PFS. The R-FC regimen (HR 2.27 [1.01–5.21]) or FC regimen (HR 3.17 [1.15–8.71]) was inferior to the VR-CAP regimen with a worse OS. The research was funded by: This work was supported by Achievement Transformation Project (No. CGZH21001), 1.3.5 Project for Disciplines of Excellence, West China Hospital, Sichuan University (No. ZYJC21007), Translational Research Grant of NCRCH (No. 2021WWB03), Chengdu Science and Technology Program (No. 2022-YF05-01443-SN, 2022-YF05-01444-SN), Key Research and Development Program of Sichuan Province (No. 2023YFS0031, 2023YFS0306), National Natural Science Foundation of China (No. 82204490), and National Key Research and Development Program of China (No. 2022YFC2502600, 2022YFC2502603). Keywords: Aggressive B-cell non-Hodgkin lymphoma, Chemotherapy, Immunotherapy No conflicts of interests pertinent to the abstract.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Diffuse Large B- cell Lymphoma (DLBCL) is characterized by genetic and clinical heterogeneity. Different loci within the human leukocyte antigen (HLA) region have been implicated in susceptibility and disease control of DLBCL. Methods: HLA typing was performed using Sequence-Specific Oligonucleotide (SSO) and Sequence-Specific Primer (SSP) in 60 DLBCL patients and 250 healthy adult donors from local Bone Marrow registry. Statistical analysis was conducted with version 29.0 of IBM SPSS. The phenotypic frequencies of HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 between patients and controls were compared with the 2-sided Fisher’s exact test. Results with p-value < 0.05 were considered statistically significant. Odds Ratios (OR) with 95% Confidence Intervals were calculated to further strength the results. Additionally, a follow-up analysis was performed by calculating Bonferroni-adjusted p-values (pc). Thereafter HLA polymorphisms that showed statistically significant difference were included in univariate and multivariate survival analysis together with the patients clinical-biological characteristics (age, stage, LDH, R-IPI). The R programming language, version 4.2.2 and specifically the “survivalAnalysis” package version 0.3.0. were used to investigate the associations of each factor with the Overall Survival (OS) and the Progression Free Survival (PFS). Results: DLBCL patients displayed a lower frequency of HLA-C*12 (6.7% vs. 34.7%, p = 0.001, pc = 0.00001, OR = 0.13, 95% CI [0.05, 0.38]), HLA-DRB1*16 (15% vs. 29.7%, p = 0.02, pc = 0.04, OR = 0.42, 95% CI [0.19, 0.89]) and HLA-DRB1*03 (58.3% vs. 77.5%, p = 0.02, pc = 0.01, OR = 0.40, 95% CI [0.22, 0.74]) compared to healthy individuals. In univariate analysis only advanced stage, high LDH and low versus high R-IPI had statistically significant impact on OS (p values 0.007, 0.003 and 0.002 respectively) and PFS (p-values 0.001, 0.002 and <0.001 respectively). Interestingly the Cox regression analysis used to evaluate the impact of LDH together with the HLA-DQB1*03 polymorphism on OS showed that although normal LDH is a good prognostic factor with HR = 0.33 95% CI [0.17 – 0.65] p-value = 0.001), the combination of normal LDH with DQB1*03 with HR 2.07 95% CI [1.06–4.07] indicates a significantly increased risk of death (p-value = 0.034). Regarding PFS the LDH- DQB1*03 model displayed also statistical significancy (p = 0.001) in a similar way with DQB1*03 increasing the risk of death while keeping LDH within normal ranges. Conclusions: Our results suggest that DLBCL patients express certain genetic types of HLA in lower frequency compared to healthy individuals. Antigens represented less frequently may act protectively in the development of the DLBCL. However, the presence of rarely represented HLA types failed to prove any positive impact on OS and PFS indicating the complexity of DLBCL pathogenesis. Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers No conflicts of interests pertinent to the abstract.

LIFETIME TREATMENT BURDEN OF PATIENTS WITH MANTLE CELL LYMPHOMA: SIMULATION‐BASED ANALYSIS OF REAL‐WORLD DATA FROM 20 YEARS

Background: Mantle cell lymphoma (MCL) is a rare subtype of B-cell lymphoma that is currently considered incurable, yet treatable condition with increasing amount of treatment options. Alas, the availability of novel therapies is often limited to later treatment lines due to their excessive cost. In this study, we aimed to conduct a baseline analysis on the lifetime treatment burden of MCL patients treated with conventional chemoimmunotherapy regimes. Specifically, we wanted to estimate the number of treatment lines received during 20-year follow-up to determine the number of MCL patients that could potentially receive novel, targeted therapies during the follow-up period. Methods: A real-world data set of 548 patients diagnosed and treated for MCL between the years 2000 and 2020 was collected from seven Finnish hospitals and one Spanish hospital. First, this data was analyzed using the traditional methods of survival analysis for overall survival, time to progression and follow-up time. From these initial results, we estimated the risk of progression from the first treatment line to subsequent treatment lines, to death from MCL, or death from other causes. These estimates were then applied in our competing risk analysis based on Weibull distribution and the data was completed by dynamic imputation of health event histories using discrete semi-Markov transitions in a limited time space to extrapolate the censored variables from our data set up to 20 years of follow-up for each patient. A state distribution plot from our analysis is shown below (Figure 1). Results: In our original data set, the median duration of follow-up was three years (range 0 to 18 years). At 10 years of simulated follow-up, 525 (95.8%) patients had received first-line therapy, 307 (56.0%) had received second-line therapy, 148 (27.0%) had received third-line therapy and 64 (11.7%) had received fourth-line therapy. A total of 262 (47.8%) patients had died from MCL and 113 (20.6%) from other causes. After 20 years of simulated follow-up, the respective figures were 525 (95.8%), 373 (68.1%), 192 (35.0%) and 85 (15.5 %). A total of 362 (66.1%) of patients had died from MCL and 166 (30.3%) from other causes. The median number of treatment lines received both at 10 and 20 years of follow-up was three. Figure 1. State distribution plot from 20-year follow-up The research was funded by: North Ostrobothnia Health Care District Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cancer Health Disparities No conflicts of interests pertinent to the abstract.

REMISSION AFTER CAR T‐CELLS: DO PATIENTS RECOVER A NORMAL LIFE?

Introduction: CD19 CAR T-cells can induce prolonged remission in a significant number of patients with relapse/refractory (R/R) lymphoma. However, little is known about patients’ life after CAR T-cell therapy. Here, we conducted a prospective study to evaluate health-related quality of life (HRQol), as well as physical, social and professional outcomes after CAR T-cell therapy. Methods: This prospective study was conducted at the University Hospitals of Rennes and Toulouse (France). All adult patients with R/R lymphoma treated with CAR T-cells were eligible. HRQol changes were assessed using the FACT-Lym questionnaire. Other questionnaires evaluated cognitive state (FACT-Cog), fatigue (FACT-Fatigue), anxiety and depression (HAD scale), post-traumatic stress disorder (PTSD), and sexuality (Vican). Questionnaires were collected at baseline (before leukapheresis), immediately before CAR-T infusion, 3 and 6 months after CAR T-cell infusion. Patients were censored in case of relapse or death. Among patients in remission after 12 months, professional, physical, sexual and global life information were collected. Results: From March 2020 to August 2022, 59 patients were included in the study (46 LBCL, 5 MCL, 8 FL). Median age was 63 years (range, 19–78). Patients were treated with axi-cel (N = 37), tisa-cel (N = 18) or brexu-cel (N = 3). The median follow-up after CAR T-cell infusion was 11 months. There were 53 and 38 still in remission at 3 and 6 months after CAR T-cell infusion, respectively. The FACT-Lym score showed a clinically relevant improvement of HRQol, with a mean change from baseline of 10.9 points (95%CI 5.8; 16.1) and 12.2 (95%CI 4.2; 20.1), respectively. The fatigue subscale showed a clinically relevant improvement at 3 and 6 months, with a mean change from baseline of 5.9 points (95%CI 2.9; 8.8) and 4.7 (95%CI 0.2; 9.2), respectively. The FACT-Cog score did not show any clinically relevant change. The HAD score showed that 43% and 24% of patients presented anxiety and depression at baseline, respectively, versus 26% and 7% after 6 months. Overall, 26% of patients presented a significant PTSD (i.e., >44) at 6 months. 54.5% of the patients considered that their life was back to normal (before lymphoma diagnosis); 68.2% patients were satisfied with their sexual life, 59.1% considered that it was back to normal; 54% felt less fit than before lymphoma; 21/21 patients practicing a physical activity before lymphoma resumed their activity; 3/8 resumed their social activity; Among the working age population (n = 10), 50% patients had returned to work. Encore Abstract - previously submitted to EHA 2023 Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cellular therapies, Other Conflicts of interests pertinent to the abstract F. Colin Consultant or advisory role Gilead, Novartis A. Anota Consultant or advisory role AMGEN, IPSEN, ASTRAZENECA, KITE-GILEAD Educational grants: KITE GILEAD L. Ysebaert Consultant or advisory role AstraZeneca, Beigene, BMS/Celgene, Janssen, Gilead/Kite R. Houot Consultant or advisory role Kite/Gilead Honoraria: Bristol Myers Squibb/Celgene, MSD, Kite/Gilead, Roche, Novartis, Janssen A. Moignet Consultant or advisory role Kite, Novartis

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Background: R-CHOP immunochemotherapy is the first-line treatment for DLBCL, but approximately 30%–40% of patients still experience refractory or relapsed (R/R) disease. We aimed to characterize the molecular features of DLBCL derived from patients with early R/R disease and develop a prognosis model to identify those high-risk patients. Methods: We performed a comprehensive genomic and transcriptomic characterization on 161 R-CHOP-treated DLBCL samples. These patients were grouped by follow-up outcome status after R-CHOP treatment. The first group had R/R disease within two years of diagnosis (poor outcome; n = 50), and the second group remained in remission at two years following R-CHOP treatment (good outcome; n = 111). In an addition, external cohorts were included in the validation analysis (GSE117556, n = 374; GSE181063, n = 810). Results: Patients with poor outcomes more often had an advanced stage of the disease, a high international prognostic index (IPI) and a non-GCB subtype of the tumor. We identified a set of frequent somatically mutated targets (Figure 1A), including PIM1, TP53, MPEG1 and ROBO1, as well as a specific mutational signature (activation-induced cytidine deaminase related) in DLBCLs with poor outcomes. Transcriptomic analyses further showed a distinct gene expression pattern and a less inflamed tumor microenvironment in these patients (Figure 1B). Finally, we developed an 11-gene signature as an independent prognostic marker for DLBCL patients treated with R-CHOP (Figure 1C). The 11-gene signature could further stratify DLBCL patients based on their IPI scores (Figure 1D). Additionally, the use of 11-gene signature to identify high-risk patients was also validated in two independent cohorts, suggesting the robustness of the risk model. Furthermore, our model effectively identified high-risk patients, including those with double-hit and MCD genetic subtypes that are associated with poor survival outcomes. FIGURE 1 (A) The mutation pattern between poor outcome and good outcome DLBCLs. (B) Tumor-infiltrating immune cells in DLBCL patients with poor and good outcomes. (C-D) Kaplan–Meier survival analysis of PFS between high-risk and low-risk groups (C) and the association of 11-gene risk scores and IPI risk groups (D). Keywords: Aggressive B-cell non-Hodgkin lymphoma, Diagnostic and Prognostic Biomarkers, Genomics, Epigenomics, and Other -Omics No conflicts of interests pertinent to the abstract.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: R-CHOP remains the standard of care in DLBCL yet for up to 40% of patients (pts.) it fails either through refractory lymphoma or relapse after achieving an initial remission. In the phase Ib/II ACCEPT study (NCT03571308), acalabrutinib (A), a second generation Bruton Tyrosine Kinase inhibitor with enhanced kinase selectivity and a potential for better tolerability, was assessed in combination with R-CHOP in patients with de novo DLBCL. There were no dose-limiting toxicities and the maximum tolerated dose was not reached, At the recommended phase II dose of A 100 mg bd, R-CHOP+A demonstrated a 95% 24 month progression-free survival (PFS). In older patients there was no difference in safety and no compromise of delivery of full course R-CHOP. Efficacy was preserved across cell-of-origin and genomic sub-groups. The REMoDL-A study now builds upon these findings to examine efficacy of R-CHOP+A against R-CHOP. Methods: REMoDL-A is a stratified open-label, multicentre, randomised phase II study. Eligible patients have untreated histologically confirmed DLBCL requiring full course R-CHOP. All patients receive 1 cycle of R-CHOP chemotherapy. FFPE diagnostic pathology blocks have molecular profiling and are assigned subtype Germinal Centre B-cell, Activated B-Cell, Molecular High Grade, Unclassifiable, or failed RNA extraction (GEP Fail). Patients whose biopsies are successfully sub-typed are randomised 2:1 between R-CHOP+A (Arm B) or R-CHOP for a further 5 cycles (Arm A). The randomisation is stratified by molecular subtype, International Prognostic index and age. The primary endpoint for the study is progression free survival (PFS) in the modified intention to treat (ITT) population (non-Fail ITT population). Secondary endpoints include PFS related to the cell of origin and genomic subtypes, duration of response, overall survival, event free survival, toxicity and quality of life. Exploratory analyses will investigate how dynamic molecular (including CTDNA) and PET based biomarkers predict risk and can be incorporated into a dynamic risk prediction model. An early interim analysis is planned to explore safety in the ≥65 years population. The trial is powered to detect a hazard ratio of 0.668 with 90% power with 1-sided significance level of 20%. The number of patients to be randomised is 453 (302:151 per arm). To date 155 patients have been recruited. Of the FFPE diagnostic pathology blocks that have undergone molecular profiling, failed RNA extraction (GEP fail) has occurred in only 4 patients. This is a UK National Cancer Research Institute multicentre trial coordinated by Southampton Clinical Trials Unit. Molecular profiling is performed in HMDS, Leeds. Trial registration: ISRCTN14251143/ NCT04546620 The trial has been supported by an investigator initiated grant and drug access from AstraZeneca (ESR-19-20180) and has endorsement from Cancer Research UK (CRUKE/19/017). Keywords: aggressive B-cell non-Hodgkin lymphoma, combination therapies, ongoing trials Conflicts of interests pertinent to the abstract G. P. Collins Honoraria: Roche, AstraZeneca C. Fox Consultant or advisory role Abbvie, AstraZeneca, Atarabio, BMS, GenMab, Gilead/Kite, Incyte, Lilly, Morphosys, Ono, Roche, Takeda Research funding: Beigene Educational grants: Roche, BMS G. Griffiths Honoraria: AstraZeneca P. Johnson Honoraria: Takeda, InCyte, Genmab, Epizyme A. J. Davies Consultant or advisory role Celgene, Roche, Kite, Takeda, Incyte Honoraria: Celgene, Roche, Kite, Takeda Research funding: Celgene, Roche, Kite, Takeda, Janssen, GSK Educational grants: Celgene, Roche

Impact of the Affordable Care Act and Medicaid Expansion on Insurance Coverage and Outcomes in Patients with HIV‐associated Aggressive B‐cell Non‐Hodgkin Lymphomas

Introduction: HIV-associated lymphomas affect a uniquely disadvantaged group of patients, who were often denied insurance based on preexisting conditions until the Affordable Care Act (ACA) was signed in 2010. We investigated the impact of ACA and its Medicaid expansion in 2014 which covered the low-income strata, on outcomes among patients with HIV-associated aggressive B-cell non-Hodgkin lymphomas (HIV-aB-NHL). Methods: We used the National cancer database (NCDB) to identify HIV-associated aB-NHL patients aged 18–64 years from 2004 to 2017. We defined the pre-ACA period up to 2013 and the post-ACA period after 2014. States were grouped as Medicaid expansion adopted or not adopted. To reduce bias from advancements in anti-retroviral and chemo-immuno-therapies, we compared survival outcomes between 2010 to 2013 and 2014 to 2017. Kaplan-Meier method and a parametric Weibull model were used for survival analysis. Results: We identified 10,795 eligible patients with HIV-associated aB-NHL, comprised of 1802 Hispanics (16.7%), 3915 non-Hispanic blacks [NHB (36.3%)], 4727 Non-Hispanic Whites [NHW (43.8%)] and 351 other minorities (3.2%). The predominant diagnoses were diffuse large B-cell lymphoma (63.3%) and Burkitt lymphoma (20.1%). The figure shows the distribution of insurance status at diagnosis in Medicaid expansion (n = 4611) and non-expansion (n = 3091) states before and after the implementation of ACA stratified by race. Hispanics were more likely to be from residential zip codes in the lower educational quartile. A higher proportion of patients were seen at academic medical centers in expansion states across all races, and this further improved post-ACA. There was a significant improvement in survival seen among NHB (p < 0.01) post-ACA though the trend in Hispanics was not significant (P = 0.36). A multivariable survival analysis using the Weibull model adjusting for age, sex, insurance status, Charlson-Deyo comorbidity index, income, race, and Medicaid expansion status found statistically significant improvement in the states that adopted Medicaid expansion (HR 0.88, p < 0.01) though NHB race predicted poor survival (HR 1.49, p < 0.01). Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cancer Health Disparities Conflicts of interests pertinent to the abstract. L. D. Anderson Consultant or advisory role: Celgene, BMS, Amgen, GSK, Janssen, Karyopharm, Beigene, AbbVie, Cellectar, and Sanofi Y. F. Madanat Consultant or advisory role: BluePrint Medicines, GERON, OncLive, Sierra Oncology, Stemline Therapeutics and Novartis G. Kaur Honoraria: BMS and Cellectar F. T. Awan Consultant or advisory role: Genentech, Astrazeneca, Abbvie, Janssen, Pharmacyclics, Gilead sciences, Kite pharma, Celgene, Karyopharm, MEI Pharma, Verastem, Incyte, Beigene, Johnson and Johnson, Dava Oncology, BMS, Merck, Cardinal Health, ADCT therapeutics, Epizyme, Caribou Biosciences, Cellecter Bisosciences Research funding: Pharmacyclics P. Ramakrishnan Geethakumari Consultant or advisory role: Kite Pharma, Bristol Myers Squibb, Rafael Pharma, Pharmacyclics LLC, ADC Therapeutics and Cellectar Biosciences

RHOA deficiency drives decreased CD19 expression and immune dysregulation in CAR‐T resistant diffuse large B‐cell lymphoma

Background: CD19-directed chimeric antigen receptor T-cell (CAR-19) therapies are promising new options in relapsed or refractory diffuse large B-cell lymphoma (DLBCL), but over half of patients still progress. Recent whole-genome sequencing data published by our lab revealed that deletion of RHOA (3p21.31) is strongly associated with poor response (p = 0.0013). In newly diagnosed DLBCL, 20% of patients harbor a RHOA deletion and another 5% have loss-of-function mutations. To date, no work has comprehensively identified the role of RHOA in DLBCL or how its inactivation may protect CAR-19 resistant tumors. Methods: RHOA loss-of-function (LoF) lymphoma cell lines were generated using shRNA and CRISPR approaches. Diminished RHOA activity was confirmed via active RHO pulldowns. RNA-sequencing in conjunction with western blotting and flow cytometry was conducted to uncover deregulated pathways in RHOA-deficient lymphoma. Cell proliferation, migration, and viability were assessed to phenotype RHOA LoF and uncover signaling pathways activated in RHOA-deficient lymphoma. CD19-directed murine and human CAR-T cells were co-cultured with corresponding RHOA LoF systems to assess CAR-T engagement and killing. Results: RNA-seq analysis of RHOA-deficient cell lines revealed enrichment of gene sets associated with cell-cycle progression and interferon signaling pathways, and cell proliferation and chemotaxis assays both demonstrated increased activation. Western blotting revealed upregulated pAKT, but strikingly RHOA LoF systems showed enhanced sensitivity to PI3K, AKT, and mTOR inhibition. We assessed if RHOA LoF associates with previously described decreased CD19 driving CAR-19 resistance and found consistent downregulation by flow cytometry in both A20 shRhoa (p = 0.0002) murine lymphomas and RIVA human cell line CRISPR het RHOA knockouts (p = 0.0031), confirmed by western blotting in both systems. RNA-seq analysis of 74 DLBCL patients (PCAWG data) revealed a strong positive correlation between expression CD19 and RHOA (p < 0.001, R2 = 0.236). Impedance-based serial cell viability assessments and flow cytometry cytotoxicity assays with CAR-19 and RHOA LoF cells revealed a statistically significant decrease in CAR-19 killing of RHOA-deficient lymphomas (p = 0.0005 and p < 0.0001). Conclusion: RHOA-deficient lymphoma relies on PI3K/AKT/mTOR signaling for proliferation that works in parallel with decreased CD19 to decrease CAR-19 killing. Upregulation of interferon signaling pathways gives evidence of increased immunoinhibitory ligands that could promote exhausted CAR19 products. Further research will challenge in vivo RHOA-deficient tumors with CAR-19 cells and employ scRNA-seq to reveal transcriptomic changes within RHOA-deficient lymphoma responsible for CAR-19 resistance. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Immunotherapy, Microenvironment No conflicts of interests pertinent to the abstract.

How to choose between curative radiotherapy or chemotherapy in low stage MCL?—a population‐based analysis of outcome in patients with stage I‐II MCL in Sweden

Introduction: The optimal primary treatment of mantle cell lymphoma is not yet defined with respect to long-term disease control and manageable toxicity. A few patients with MCL present with limited stage disease and for these, involved node radiotherapy may be a well tolerable alternative to immunochemotherapy regimens. Here, we aim to evaluate progression free survival (PFS) and overall survival (OS) in relation to given treatment and prognostic factors in patients with stage I-II MCL. Methods: The study was based on patients diagnosed with MCL in Sweden 2006–2018 according to the Swedish Lymphoma Register (SLR), which is a nationwide population-based register with a reported coverage of 95%. Data were supplemented by review of medical records for all patients. Survival analyses were made by Kaplan-Meier estimates with end of given treatment as start of follow-up (FU). Results: Out of all patients (n = 1412), we identified a cohort of 173 patients reported with Ann Arbor I-II or Musshoff PeI according to standard staging procedure. Median age was 71(22–93) years, 88% had ECOG 0–1 and 31% were scored high-risk MIPI at diagnosis. Primary treatment included single RT (n = 48, 28%) of which curative radiation dose ≥24 Gy in 37 (21%) patients, Immunochemotherapy (ICT) (n = 94, 54%) including R-bendamustine (n = 34), Nordic MCL2 protocol (n = 28), R-CHOP (n = 14), and ICT with consolidative RT in 12 (7%) (CRT). At a median FU time of 5.40 (0.01–15.46) years (y), median OS in the cohort was 9.56 y (95% CI: 6.60-NR). 5-y-OS (95% CI) after ICT was 0.64(0.53–0.73), after single RT ≥24 Gy 0.84(0.67–0.92) and 0.58(0.27–0.80) after CRT (Figure 1a). Median progression-free survival (PFS) in the cohort was 3.55 y (95% CI: 2.53–6.08). 5-y-PFS (95% CI) was 0.47 (0.36–0.58) after ICT, 0.40 (0.24–0.55) after single RT ≥24 Gy and 0.55 (0.23–0.78) after CRT (Figure 1b). The research was funded by: Mrs Berta Kamprad´s foundation. The research was made possible in part by research funding from Janssen Pharmaceuticals AB Keywords: Aggressive B-cell non-Hodgkin lymphoma, Chemotherapy, Radiation Therapy No conflicts of interests pertinent to the abstract.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Patients with relapsed or refractory (R/R) mantle cell lymphoma (MCL) have poor outcome. Time to first relapse or progression (POD) has been consistently shown to be an independent predictor of survival, with patients experiencing early-POD, within 2 years since the diagnosis, representing a subgroup at greater risk of death. On the contrary, there is a paucity of large-scale treatment data on patients experiencing relapse beyond 2 years (late-POD). Methods: In this international, observational cohort study, we evaluated the outcomes amongst patients with first R/R MCL and late-POD, after upfront standard regimens including high dose cytarabine. Patients treated upfront with Bruton tyrosine kinase inhibitors (BTKi) were excluded. The primary objective was progression-free survival (PFS) of BTKi versus chemoimmunotherapy (CIT) as second line therapy. For sample size calculation 100 patients treated with drug 1 (BTKi), and 200 with drug 2 (CIT) were needed to compare PFS of drug 1 versus drug 2, assuming that CIT and BTKi would have a median PFS of 36 and 60 months, respectively. After accrual, all patients were prospectively followed-up. Overall survival (OS-2) and PFS-2 were estimated from the time of salvage therapy. Results: Overall, 386 late-POD patients were included from 10 countries. Median age was 59 (19–70), and 77% were males. Median follow-up from time of first relapse was 53 months (12–144). Overall, 114 patients had second-line BTKi (drug 1), while CIT (drug 2) was delivered to 271 patients, consisting of rituximab-bendamustine (R-B, n = 101), R-B and cytarabine (R-BAC, n = 70), or other regimens (mostly CHOP or platinum-based, n = 100). The two groups were balanced for clinicopathological features, and median time to first relapse (48 months for both). Overall, BTKi was associated with significantly longer median PFS-2 than CIT [51 versus 26 months, respectively, P = 0.0003, Figure 1], and OS-2 [88 and 56 months, P = 0.03]. The performance of BTKi and R-BAC were similar, both in terms of PFS-2 and OS-2, and significantly superior to R-B or other regimens (P = 0.0003, and P = 0.01, respectively). Multivariate Cox regression showed that ibrutinib was associated with inferior risk of death than R-B and other regimens (HR 2.41 for R-B, 2.17 for others), but similar to R-BAC. Blastoid variant, age, and time to POD as continuous variable were also independent predictors of OS-2. Nine patients with TP53 mutation had inferior OS-2 compared to TP53 wild-type patients (n = 48, P = 0.04). The research was funded by: The research was funded in part by Janssen, as part of a Clinical IIS Research Application Keywords: Aggressive B-cell non-Hodgkin lymphoma, Combination Therapies, Molecular Targeted Therapies No conflicts of interests pertinent to the abstract.

APR‐246 TRIGGERS FERRITINOPHAGY AND FERROPTOSIS OF DIFFUSE LARGE B‐CELL LYMPHOMA CELLS WITH DISTINCT TP53 MUTATIONS

Purpose: Recently, seven diffuse large B-cell lymphoma (DLBCL) genotypes were defined, among which the A53 type showed adverse outcomes. Thus, it is necessary to explore promising anticancer drugs and therapies for TP53 dysfunction patients. APR-246 is a promising compound to combat mutant p53 in solid and hematological tumors, but the effect of APR-246 on DLBCL remains unclear. Methods: A set of 2464 DLBCL cases from multiple cohorts including our center, was integrated to identify the type and localization of TP53 mutations and clinical impacts. APR-246 was applied in TP53-mutated DLBCL cells and xenograft mouse models to explore the anti-tumor effect and the underlying mechanism. Results: Of all patients, 16% contained TP53 mutations. TP53 mutations correlated with poor overall survival (OS) and progression-free survival (PFS) in all cases. Notably, TP53single mutations in the DBD (exons 5-8) resulted in poor OS and PFS, but those on the exons (3-4, 9-11) outside the DBD. DLBCL cells carrying exons 5 and 7 or intact TP53 mutations showed more sensitivity to APR-246 than those containing spliced mutations or null TP53. DLBCL cells with knocked-out TP53 showed less sensitivity to APR-246. APR-246 also significantly inhibited the DLBCL tumor growth in xenograft animal model. The decreased cell viability induced by APR-246 was almost completely rescued by either the iron chelater deferoxamine (DFO) or ferrostatin-1 (Fer-1), indicating that ferroptosis mediates cell death. APR-246-induced cell death is an action involving ROS production, which was not altered by knockout of TP53 in OCI-LY7. However, only ferroptosis was induced by APR-246 in OCI-LY3, TMD8 and TP53-knockout OCI-LY7 cells, indicating that APR-246-induced autophagy in OCI-LY7 was TP53-dependent. Further, the cells re-expressing wild-type p53 showed the similar response as OCI-LY3 harboring wild-type p53 to APR-246, while the cells with re-expressed p53 mutant showed the similar response as OCI-LY7 to APR-246. The expression of ALOX5, ALOX12, and ALOX15 were increased in DLBCL cells after APR-246 treatment for 24 h. The LC3-II level was enhanced while the autophagy substrate SQSTM1 was reduced by APR-246 treatment, confirming APR-246 induces autophagy in OCI-LY7 cells. Additionally, FTH1, NCOA4 and HERC2 were also examined in TP53 knockout DLBCL cells, and the data demonstrated that APR-246 had no effect on the level of these proteins, indicating that APR-246 restored p53 was involved in ferritinophagy in OCI-LY7 cells. These findings were further confirmed in OCI-LY7 TP53-KO cells with re-expressing mutant or wild-type p53. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Diagnostic and Prognostic Biomarkers, Genomics, Epigenomics, and Other -Omics No conflicts of interests pertinent to the abstract.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Anbal-cel is a novel autologous anti-CD19 CAR-T cell therapy which has been knocked-down for PD-1 and TIGIT expression using OVIS platform. It demonstrated superior T-cell functionality compared to other marketed CD19 CAR-T cells at preclinical studies. Phase 1 dose escalation study confirmed anbal-cel is safe and potentially effective. Methods: Patients with relapsed or refractory LBCL were enrolled from six Korean investigator sites to receive anbal-cel at a dose of 2 × 106 CAR-T cells/kg. Primary endpoint is objective response rate (ORR) assessed by Independent Review Committee (IRC). Secondary endpoints are progression-free survival (PFS), duration of response (DOR), pharmacokinetics (PK) and safety profiles. Results: As of 28 February 2023, a total of 41 patients were infused and 34 patients completed at least one tumor response evaluation at day 28. With the median age of 63 (range 37–82), 66% of the patients (27/41) were double expressor. Non-GCB type was 76% (31/41) and 42% (17/41) were primary refractory patients. Median follow-up period was 4.6 months. ORR (CR/PR) assessed by investigators was 85.3% and CR rate at day 28 & month 3 were 73.5% (25/34) and 71.4% (22/31) respectively. IRC assessment result was similar and will be presented at the meeting. Among the 41 patients, grade 3 CRS and ICANS were reported from 6 patients (14.6%) and 2 patients (4.9%) respectively. No grade 4 CRS and ICANS was observed. Prolonged neutropenia was observed in 11 patients (26.8%) and thrombocytopenia was observed in 12 patients (29.3%). Three (7.3%) serious infections (1 bacteria and 2 COVID-19 infections) were reported during primary follow-up period. Responder group (CR) reported higher incidence and severity of CRS compared to non-responder group (Non-CR), but it was insignificant. Incidence rate, severity of ICANS and prolonged cytopenia were comparable between the two groups. Among CAR+ T-cells in the anbal-cel product, median CD4:CD8 ratio was 3.6 and CCR7+ memory phenotype CAR T-cells account for 65.8% of CAR-T cells. Median knock-down rates of PD-1 and TIGIT were 65% and 96% respectively. The responder group showed a significantly increased level of CCR7+ memory phenotype (68.6% vs. 44.9%) and PD-1 knock-down rate (71.8% vs. 59.3%) compared to the non-responder group, which showed correlation with increased levels of AUC0-28days and Cmax. Anbal-cel expansion was not correlated to tumor volume measured by SPD and TMTV. In addition, the responder group had notable changes in cytokine levels of IL-2, IL-10, IFN-γ, granzyme, GM-CSF and peak levels of various cytokines were proportional to severity of CRS. Patients with higher levels of IL-15 and MCP-1 at baseline had tendency to experience ICANS. Conclusions: Anbal-cel demonstrated unique characteristics in product profile which demonstrated potential to correlate with treatment outcomes and warrant to confirm with more data. The research was funded by: Curocell Inc. Keywords: aggressive B-cell non-Hodgkin lymphoma, cellular therapies, immunotherapy No conflicts of interests pertinent to the abstract.

CTPS1 acts as a prognostic biomarker and therapeutic target in mantle cell lymphoma

Introduction: Mantle cell lymphoma (MCL) represents 6 to 8% of non-Hodgkin’s lymphoma with generally poor prognosis. Cytidine triphosphate synthase 1 (CTPS1) is a critical regulatory enzyme in cytidine metabolism, catalyzing the rate-limiting step in de novo CTP synthesis. Herein, we aim to investigate the clinical significance and functional mechanisms of CTPS1 in MCL patients. Methods: Lymph node, bone marrow biopsy, peripheral blood specimens and MCL cell lines were utilized as models. Liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS)-based analysis was performed to measure the steady-state level of metabolites. GSE93291 dataset and immunohistochemistry (IHC) staining were utilized to determine the relationship between expression levels of CTPS1 and patient outcome. CRISPR/Cas9 editing was employed to engineer the loss-of-function models of CTPS1 and other key enzymes involved in CTP synthesis. Results: Metabolic Profiling revealed dramatically aberrant cellular abundance of metabolic intermediates in the CTP synthesis pathway (Figure 1A). For GSE93291 analysis, a nucleotide metabolism related prognostic model was established by bioinformatic analysis and CTPS1 was screened out by highest regression coefficient (Figure 1B). IHC staining of CTPS1 in 105 MCL tissues confirmed that elevated CTPS1 expression was significantly associated with poor PFS (P = 0.038) and OS (P = 0.001) in MCL patients (Figure 1C-D). Multivariate Cox regression analysis showed that high CTPS1 expression was an independent prognostic indicator of both PFS and OS. CTPS1 depletion significantly impaired outgrowth and increased apoptosis of MCL cells, suggesting that CTPS1 is the major isozyme important for MCL survival (Figure 1E-F). In primary tumor samples, MYC protein levels were significantly correlated with CTPS1 protein levels (P < 0.001, R = 0.638). MYC knockout blocked CTPS1 mRNA and protein expression prior to induction of cell death, suggesting a requisite role of MYC in CTPS1 transcription regulation (Figure 1G). Remarkably, TP53 aberrant and ibrutinib-resistant MCL cells rely on cytidine metabolism (Figure 1H). Genetic or chemical inhibition (3-deazauridine) of CTPS1 reversed poor responsiveness of MCL cell lines to ibrutinib (Figure 1I). Cytidine level was significantly increased in TP53-deficient MCL cells and the effect of CTPS1 inhibition was independent of TP53 status (Figure 1K). Gene set enrichment analysis of RNA-sequencing revealed that CTPS1 inhibition induced DNA damage and apoptosis. Moreover, CTPS1 inhibition caused cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) activation, which triggered innate immune pathway, leading to cells growth inhibition (Figure 1L). Keywords: Aggressive B-cell non-Hodgkin lymphoma, Diagnostic and Prognostic Biomarkers, Metabolism No conflicts of interests pertinent to the abstract.

AUTOLOGOUS HEMATOPOIETIC CELL TRANSPLANTATION FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA (PCNSL). REAL‐WORLD REPORT OF POLISH LYMPHOMA RESEARCH GROUP.

Introduction: High-dose chemotherapy with autologous stem-cell transplantation (HDC-ASCT) is now the preferred consolidation strategy for young PCNSL patients. The optimal conditioning regimen is unknown. The data suggests that BEAM (carmustine, etoposide, cytarabine, melphalan) is ineffective, BCNU/TT (carmustine/thiotepa) is well-tolerated with treatment related mortality (TRM) 1%–3%, but late relapses are common, and TBC (thiotepa, busulfan, cyclophosphamide) is highly effective but with higher TRM 11%. Methods: The aim of the study was to analyze the safety and efficacy of consolidation based on conditioning regimen consisted of carmustine, etoposide and thiotepa (BET)1 followed by ASCT. We evaluated the outcome of 45 immunocompetent adult patients with PCNSL treated in 4 Polish centers between Feb. 2015 and Oct. 2022. Six cycles of induction with rituximab, methotrexate (3.5 g/m2), ifosfamide and vincristine (R-MIV) and one cycle of cytarabine with thiotepa (AT)2 were given. Patients with a complete or partial response (CR/PR) proceeded to consolidation with carmustine 400 mg/m2 on day -5, etoposide 150 mg/m2 on day -5,-4, -3, and thiotepa 5 mg/kg every 12 h on days -4 and -3 (total 4 doses), followed by ASCT. Results: Median age (range) of 45 transplanted patients was 57 years (19-66) with 15 (33%) patients ≥60 years old. At the end of induction 29 (64.5%) patients obtained CR/CRun (19/10 respectively), with additional 5 (11%) patients with no evidence of disease at baseline, and 11 (24.5%) in PR, based on standard CT/MRI assessment. For 32 (71%) patients with 18FDG PET/CT done before ASCT, metabolic-CR was confirmed. Mean (range) number of 584.4 (187–2642) × 106 CD34+ peripheral blood stem cells were collected, corresponding to 7.2 × 106 cells/kg (2.55–34.7 × 106 cells/kg). Mean hospitalization time from the day of ASCT was 15 days. Mean time to hematologic recovery with PLT > 25 G/L and NEU > 0.5/ > 1.0 G/L was 9 and 9/10 days, respectively. The most common grade 3–4 non-haematological toxicities were diarrhea (12 patients, mean 4 days) and mucositis (18 patients, mean 5 days). Febrile neutropenia occurred in 21 patients (mean 2.5 days). Blood cultures did not reveal any relevant pathogens except one patient with confirmed Enterobacter cloacae-ESBL and Klebsiella oxytoca. Two patients (TRM 4.4%) died of transplant-related complications: septic shock and neurotoxicity. At a median (range) follow-up of 41 (13-92) months, 3-year progression free survival (PFS) and overall survival (OS) was 78% (95% CI: 65-91) and 81% (95% CI: 68-93). Relapse occurred in 9 patients, in all but one within first 11 months after ASCT. Causes of death were: lymphoma progression (n = 6), TRM (n = 2), accident (n = 1) and concomitant diseases (n = 2). Keywords: aggressive B-cell non-Hodgkin lymphoma, stem cell transplant No conflicts of interests pertinent to the abstract.

BV6, AN ANTAGONIST OF INHIBITOR OF APOPTOSIS PROTEINS, SENSITIZES RESISTANT MANTLE CELL LYMPHOMA CELLS TO VENETOCLAX

Introduction: Although Bruton’s tyrosine kinase inhibitors (BTKi) and CAR T-cell therapy have achieved remarkable efficacy in the treatment of mantle cell lymphoma (MCL), it remains incurable due to the inevitable development of therapeutic resistance. The BCL-2 inhibitor venetoclax is effective in many relapsed MCL patients, including those who progressed on BTKi, but subsequent relapse to venetoclax yields poor clinical outcomes. Hence, novel therapeutics and combination therapies are required to tackle the clinical challenges. Here, we investigated BV6, an antagonist of inhibitor of apoptosis proteins (IAPs), alone and in combination with venetoclax in multiple therapy-resistant MCL models. Methods: We performed single-cell RNA-seq to assess gene expression in ibrutinib-sensitive, ibrutinib-resistant, and dual ibrutinib-/CAR T-resistant MCL patients. Cell lines with acquired resistance to ibrutinib or venetoclax, as well as primary tumor cells from patients who relapsed after multiple therapies, were used as models of MCL resistance. CellTiter-Glo® luminescent assay was used to measure cell viability; annexin V/PI staining was used to measure the induction of apoptosis; and western blotting was used to assess IAP and apoptosis signaling protein expression across MCL cell lines after drug treatment. Results: The single-cell RNA-seq analysis demonstrated that IAP gene expression was not influenced by patient response to ibrutinib and CAR T-cell therapy, and western blotting showed that IAP proteins were broadly expressed across all MCL cell lines. To determine the on-target effects of BV6, we treated JeKo-1, JeKo-IBN-R, Mino, and Mino-VEN-R cells with BV6 and examined the expression of IAPs. BV6 treatment for 4h markedly reduced c-IAP1 and c-IAP2 expression, and moderately reduced XIAP expression. BV6 inhibited cell viability in both ibrutinib- and venetoclax-resistant cell lines, and BV6 treatment for 24 h dose-dependently induced apoptosis in MCL cells, including not only cell lines with acquired resistance but also patient primary cells, independent of their resistance to ibrutinib, venetoclax, and CAR T-cell therapy. We observed a striking and significant synergy in the cell viability assay when ibrutinib- or venetoclax-resistant cells were treated with BV6 combined with venetoclax (combination index < 1), and a dramatic enhancement of apoptosis (p < 0.001). The combination eradicated c-IAP1 and c-IAP2 expression, while XIAP was synergistically diminished. This was accompanied by strong caspase-3 activation and PARP cleavage. This combination therapy is currently under evaluation in venetoclax-resistant mouse model in vivo. Conclusions: Our findings indicate that a combination of IAP antagonists with apoptosis inducers can be exploited as a rational strategy to overcome therapeutic resistance in MCL. This study was supported by philanthropic funds from the Kimmel Research fund and various donor funds. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Combination Therapies, Molecular Targeted Therapies No conflicts of interests pertinent to the abstract.

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: N-acetyltransferase 10 (NAT10) is the only confirmed regulator to mediate the N4-acetylcytidine (ac4C) modification of mRNA and is crucial for mRNA stability and translation efficiency. However, its role in diffuse large B-cell lymphoma (DLBCL) development and prognosis has not yet been explored. Herein, we explored the functional significance and regulatory mechanism of NAT10 mediated mRNA ac4C modification in DLBCL, which is expected to propose novel therapeutic strategy. Methods: The expression levels of NAT10 were evaluated in DLBCL cell lines and lymph node biopsies tissues, and its prognostic value in patients was further analyzed. Stable NAT10 knockout DLBCL cell lines were constructed using CRISPR/Cas9 mediated genomic deletion. The biological functions of NAT10 in DLBCL cells were analyzed in vitro by cell proliferation and cell cycle assays. Xenograft models were used to analyze the effect of NAT10 on the tumorigenesis of DLBCL cells in vivo. RNA sequencing, acetylated RNA immunoprecipitation sequencing (acRIP-seq), LC-MS/MS, RIP and RNA stability analyses were performed to explore the mechanism by which NAT10 functions in DLBCL progression. Results: NAT10 was upregulated in DLBCL cell lines and tissues. NAT10 high expression was associated with poor patient prognosis. Knockout of NAT10 impaired cellular phase progression and proliferation of DLBCL. Further analysis revealed that NAT10-mediated ac4C acetylation of SLC30A9 transcript and subsequently stabilized SLC30A9 mRNA, leading to activation of AMPK signaling and thereby facilitating DLBCL progression (Figure 1). Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers, genomics, epigenomics, and other -omics No conflicts of interests pertinent to the abstract.

IDENTIFICATION OF GENOMIC BIOMARKERS OF DISEASE PROGRESSION AND SURVIVAL IN NEWLY‐DIAGNOSED PRIMARY CNS LYMPHOMA

Introduction: There is a significant unmet need for robust genomic biomarkers that identify patients with newly-diagnosed primary CNS lymphoma (PCNSL) at high risk of progression, both during standard methotrexate-based induction as well as after dose-intensive consolidation. Methods: We performed targeted next-generation sequencing of 529 cancer genes of formalin-fixed, paraffin-embedded tumors from 74 patients with newly diagnosed primary CNS diffuse large B-cell lymphoma using the UCSF500 Cancer Panel and the Institute for Human Genetics CLIA Laboratory. The assay detects structural variants including single nucleotide variants, small insertions and deletions, and copy-number alterations (CNAs). Sixty-four EBV-negative PCNSL patients treated with a standard methotrexate, temozolomide, rituximab (MTR) induction were available for complete analysis. Results: We identified frequent mutations involving MYD88 (77%), CD79B (41.9%), ETV6 (27%) and BTG1 (25.7%) as well as frequent CNA involving 6q loss (62.5%), 9p loss (34.4%) and 12 gain (31.3%). Three genomic alterations were most significantly associated with early disease progression in PCNSL: (1) Alterations at 6p21.3, predominantly copy neutral loss of heterozygosity (CN-LOH) at the HLA Class I (HLA-A, B, C) and Class II loci (HLA-DR, DP, DQ, TAP1) as well as homozygous deletion of HLA Class II; (2) Mutations of tumor suppressor genes BTG1 and ETV6. Overall, these genomic alterations were detected in 28 out of 31 progression events in the cohort. The subgroup with either CN-LOH or homozygous deletion at 6p had the earliest progression, followed by the subgroup with mutations at either BTG1/ETV6 and no 6p CN-LOH or homozygous deletion, compared to no alterations at these 3 loci. 10 of 18 tumors with these alterations at 6p also contained BTG1 and/or ETV6 mutations. Survival analysis demonstrates that the subgroup with 6p CN-LOH or homozygous deletion had the earliest progression, followed by the subgroup with BTG1/ETV6 mutations compared to no alterations at these 3 loci (PFS p = 3.7e-5, OS p = 0.0017, logrank test, Figure 1). Multivariate Cox proportional hazard analysis demonstrated a significant 3.24-fold increased risk of progression with 6p CN-LOH/homozygous deletion or BTG1/ETV6 mutations (p = 3.5e-5, adjusted by Age, KPS, IELSG, MSKCC, IOL, Maintenance, and Consolidation). The research was funded by: National Cancer Institute NIH R01CA139-83-01A1 Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers, genomics, epigenomics, and other-omics No conflicts of interests pertinent to the abstract.

PROTEOMIC PROFILING IDENTIFIES GRANZYME B INHIBITOR SERPIN B9 AS MEDIATOR OF RESISTANCE TO CAR T‐CELL AND BISPECIFIC ANTIBODY TREATMENT IN NODAL B‐CELL LYMPHOMA

Introduction: Treatment options for relapsed or refractory (r/r) B-cell non-Hodgkin lymphomas (B-NHL) have broadened towards T-cell engaging therapies, including CD19-targeting chimeric antigen receptor T-cells (CD19-CAR) and bispecific antibodies (CD19-BsAb). Although CD19-CAR and CD19-BsAb induce durable responses in some r/r B-NHL patients, response remains heterogenous and a significant proportion of patients experience insufficient responses or relapse. A thorough understanding of tumor-intrinsic mechanisms of resistance is crucial for the clinical improvement of T-cell immunotherapy. Methods: Aiming to identify lymphoma cell-inherent mechanisms that impair response to T-cell engaging therapy, we quantified the in-vitro response of 46 B-NHL cell lines to 3rd generation CD19-CAR and CD19-BsAb. Response was measured using a high-throughput flow cytometry-based assay. In parallel, cell lines were subjected to proteomic profiling and protein abundance was regressed on in-vitro response in order to identify proteomic determinants of response. We further combined CD19-CAR treatment with clinically relevant drugs and assessed how killing of lymphoma cells and expansion of T-cells was altered. Results: Response to CD19-CAR and CD19-BsAb was highly heterogeneous across cell lines and B-NHL entities, but not significantly linked to their proliferation rate or CD19 expression. Integration of the proteomic profiles revealed that abundance of Serpin B9, endogenous inhibitor of T-cell effector molecule granzyme B, was associated with poor response to CD19-CAR and CD19-BsAb. This finding was validated in overexpression and knock-out models. Overexpression of SERPINB9 indeed attenuated response to CD19-CAR and CD19-BsAb, while its knock-out rendered cell lines more sensitive. The observed changes in susceptibility to T-cell-mediated cytotoxicity upon modulation of SERPINB9 expression were independent of T-cell donor and expression of T-cell activation and proliferation markers. We sought to improve T-cell-mediated cytotoxicity specifically in samples with high SERPINB9 expression and found that immune checkpoint inhibitors and lenalidomide enhanced expansion of CAR T-cells and increased killing of lymphoma cells. In addition, vorinostat and antibody-drug-conjugate polatuzumab vedotin specifically killed lymphoma cells without affecting T-cell expansion. However, the observed improvement in T-cell-mediated cytotoxicity was independent of SERPINB9 expression. Keywords: aggressive B-cell non-Hodgkin lymphoma, immunotherapy, indolent non-Hodgkin lymphoma No conflicts of interests pertinent to the abstract.

IMMUNE CONTEXTURE ANALYSIS IN POLARIX SUGGESTS RESPONSE TO POLA‐R‐CHP TREATMENT REDUCES TUMOR MICROENVIRONMENT DEPENDENCY

IMMUNE CONTEXTURE ANALYSIS IN POLARIX SUGGESTS RESPONSE TO POLA‐R‐CHP TREATMENT REDUCES TUMOR MICROENVIRONMENT DEPENDENCY

POLATUZUMAB VEDOTIN IN RELAPSED OR REFRACTORY DIFFUSE LARGE B‐CELL LYMPHOMA PATIENTS: A MATCHED‐CONTROL ANALYSIS FROM THE THAI LYMPHOMA STUDY GROUP (TLSG)

Treatments of patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) represent an unmet clinical need. Polatuzumab vedotin (Pola), an anti-CD79b antibody-drug-conjugate (ADC), combined with bendamustine-rituximab (BR), has recently been approved for these patients. However, there were limited data on real-life studies in R/R DLBCL, especially in Thailand. R/R DLBCL patients who received Pola-based regimens as a salvage treatment between 1 April 2021 and 30 March 2022 from the nationwide multi-center in Thailand were included in determining efficacy and safety in the real-world setting. Age, sex, and prior treatments-matched controls were selected from the database of the Thai lymphoma registry. The Pola group and historical control R/R DLBCL patients were compared. Thirty-five patients who received Pola-based treatment (Pola-BR 54.3% and Pola-R 45.7%) were included. The median age was 66 years (IQR 58–79), and the median number of prior treatments was 2 (range 1–4). The overall response rate (ORR) was 62.8%, with complete remission and partial remission of 17.1% and 45.7%. With a median follow-up of 11.8 months, the median progression-free survival (PFS) and overall survival (OS) were 10.6 months and 12.8 months, respectively. Grade 3–4 adverse events (AEs) were mainly hematological: anemia (8.6%), thrombocytopenia (5.7%), neutropenia (22.5%), and febrile neutropenia (8.6%). Compared with 180 matched patients who received non-pola-based therapy, there was a significantly higher ORR in Pola-based salvage treatments (62.8% vs. 33.3%, hazard ratio [HR] 3.52, 95% confidence interval [CI] 1.39-8.95, p < 0.01). The survival outcomes were also significantly superior in the Pola group: the median PFS 10.6 versus 4.2 months (HR 0.49; 95% CI, 0.29-0.85; p = 0.015), median OS 12.8 versus 7.5 months (HR 0.53; 95% CI, 0.34-0.84; p = 0.017). The use of Polatuzumab vedotin combination as a salvage treatment in R/R DLBCL demonstrated promising results with tolerable toxicities in the real-world setting. Keywords: aggressive B-cell non-Hodgkin lymphoma, chemotherapy, immunotherapy No conflicts of interests pertinent to the abstract.