Aggressive B-cell non-Hodgkin Lymphoma Research Articles

BONE MARROW VOLUME IRRADIATED AND RISK OF CYTOPENIAS IN AGGRESSIVE B‐CELL LYMPHOMA PATIENTS BRIDGED WITH RADIATION THERAPY FOR CART CELL THERAPY

Introduction: Patients (pts) with aggressive B cell lymphomas undergoing anti-CD19-directed chimeric antigen receptor T cell therapy (CART) can benefit from bridging radiation therapy (bRT) as immune priming. Previously, by measuring the bone marrow (BM) volume irradiated in multiple myeloma pts, we established that RT does not adversely affect stem cell collection.1 Here, we examined the impact of irradiated BM distribution on the risk of acute cytopenias after bRT prior to CART. Methods: We retrospectively reviewed adults with DLBCL between 2017 and 2022 who received bRT prior to CART, which included axicabtagene ciloleucel, tisagenlecleucel, or lisocabtagene maraleucel. Clinical characteristics, labs, and response were extracted. RT plans were reviewed; % BM irradiated was calculated as described previously with published estimates of skeletal BM distribution.2 Progression free survival (PFS), disease specific survival (DSS) and overall survival (OS) were modeled using the Kaplan-Meier method. Binary logistic regression and Mann-Whitney U correlated RT distribution with cytopenias (anemia, thrombocytopenia, and neutropenia per CTCAE v4.03). Results: Fifty-one pts received bRT, of which 13 (25.5%) had bulky disease (≥10 cm). Majority received bRT alone; 16 (31.4%) were additionally bridged with systemic therapy. The median bRT was 30 Gy (range: 4–48 Gy) and 26 pts (51%) pts received ≥30 Gy. Thirty-one pts (61%) received bRT comprehensively to all disease sites. The incidence of ≥Grade 3 cytopenias in timepoints following bRT are shown below. The median cumulative % of BM irradiated was 5.05% (range: 0%–50%). Nine pts (18%) received bRT encompassing ≥15% of the BM, for whom there was no increased incidence of ≥Grade 3 cytopenias overall (as well as specifically anemia, thrombocytopenia, and neutropenia) at any timepoint (all p > 0.2). Receipt of RT comprehensively to all disease sites, or bridging with both RT + systemic therapy, or delivery of ≥30 Gy bRT did not correlate with the incidence of ≥Grade 3 cytopenias at any timepoint. Regarding outcomes, 26 pts (51%) had CR at 30 days post-CART. Sixteen had PR (31.4%), and 9 pts (17.6%) had PD or SD. The OS/PFS were 84% (71–92)/78% (64–87) at 1 year, and 59% (44–71)/57% (42–70) at 2 years. Twenty-seven pts (52.9%) remain alive at last follow-up, 19 (70.4%) of whom have no evidence of disease. Conclusions: bRT is not associated with increased incidence of cytopenias, even for doses ≥30 Gy, when encompassing ≥15% of the BM, or when pts are treated comprehensively to all disease sites. While bRT can be delivered safely, we still urge careful field design to ensure minimum BM is treated to incorporate into pre-CART regimens. Keywords: aggressive B-cell non-Hodgkin lymphoma, cellular therapies, radiation therapy Conflicts of interests pertinent to the abstract R. E. Steiner Research funding from Seagen, BMS, GSK and Rafael pharmaceuticals.

RADIOTHERAPY BRIDGING IN LARGE B‐CELL LYMPHOMA PATIENTS RECEIVING CD19 CAR‐T – THE UK EXPERIENCE

Background: Radiotherapy (RT) has potential synergistic effects with CAR T but is not widely used as bridging therapy for lymphoma patients due to logistical challenges, uncertainty about patient selection and lack of standardised protocols. Published data on RT bridging are so far restricted to single-centre analyses. Methods: We analysed RT bridging in a large multi-centre national cohort of large B-cell lymphoma (LBCL) patients approved for 3rd line axicabtagene ciloleucel (axi-cel) or tisagenlecleucel (tisa-cel) between December 2018 and October 2022 across 12 UK centres. Results: Of 763 approved patients, 722 (95%) were leukapheresed, 717 had data available on bridging therapy. 170/717 (24%) received RT bridging, 129 as single modality and 41 as combined modality treatment (CMT). Use of RT bridging varied between centres from 11% to 32%, and increased from 19% (2018–19) to 26% (2021–22; p = 0.034). Median age of RT bridged patients was 60 y. 69% had de novo LBCL, 8% PMBL, 35% tFL and 6% transformed from other low-grade lymphoma. Disease characteristics for RT bridged patients with available data were as follows: 66% advanced stage, 41% bulk, 87% elevated LDH, 42% IPI ≥ 3, 17% double/triple hit. Patients given single modality RT were less likely to have advanced stage or ≥2 extranodal sites versus those receiving systemic therapy/CMT (61% vs. 85/83% and 18% vs. 30/39%, respectively; p < 0.05). Median time from approval to infusion was 56 days with no difference between bridging modalities. Infusion rates were 88% for RT bridging (vs. 84%, 85%, 85% for no bridging, steroids, or systemic therapy, respectively (p = 0.41)). Data on bridging (in-field) response was available for 46 RT patients: 10% CR, 65% PR, 6% SD, 10% PD. Details on RT techniques, anatomical locations and toxicities were available for 68 patients and will be provided at the meeting. Doses of 2–39 Gy were used, including combination of multiple doses; 40 patients received IMRT. Only one patient experienced G3–4 toxicity from RT. The overall incidence of G ≥ 3 CRS was 5.2% and G ≥ 3 ICANS 16.3%, with no significant difference according to bridging approaches. Median follow-up was 16 months. RT bridged patients had favourable outcomes with 1-y PFS of 56% for single modality and 47% for CMT, and 1-y OS of 65% and 56%, respectively (Figure 1). RT bridging was associated with favourable outcomes both in limited and advanced stage (1-y PFS 59% (43—72) and 50% (39–61), respectively. Keywords: aggressive B-cell non-Hodgkin lymphoma, cellular therapies, radiation therapy Conflicts of interests pertinent to the abstract A. Kuhnl Consultant or advisory role: Kite/Gilead, Novartis, BMS Honoraria: Kite/Gilead, Novartis A. Kirkwood Honoraria: Kite/Gilead A. Gibb Consultant or advisory role: Kite/Gilead A. Latif Honoraria: Kite/Gilead, Novartis

Multicenter experience with radiotherapy for relapse after chimeric antigen receptor T cell therapy in non‐Hodgkin lymphoma

Introduction: Approximately half of patients relapse following chimeric antigen receptor T-cell therapies (CAR T), a challenging clinical scenario without established treatment paradigms. Salvage radiotherapy (SRT) may be an important strategy for this population with rapidly growing, often chemotherapy-refractory disease. Limited data are available regarding SRT utilization and outcomes. Methods: We reviewed all patients with Non-Hodgkin Lymphoma treated with SRT for any intent post CAR T from 2016 to 2022 at four US cancer centers. Comprehensive SRT was defined as including all sites with PET avidity > liver max. Failure sites were classified as pre-existing (present pre SRT) versus new, and as in field, marginal (within 1 cm of), or distant with respect to SRT prescription dose region. Toxicities were graded by CTCAE v5.0. Event free and overall survival (EFS/OS) were measured from SRT start by Kaplan Meier. EFS was defined as freedom from progression, initiation of subsequent therapy, or death. Clinicodemographic associations with outcomes were assessed by Cox univariate proportional hazards. Results: 121 patients with diffuse large B cell lymphoma (DLBCL; n = 110), mantle cell lymphoma (n = 8), and primary mediastinal B cell lymphoma (n = 3) were included. Patients received axicabtagene (n = 62), tisagenlecleucel (n = 27), lisocabtagene (n = 17), experimental CAR T (n = 12), and brexucabtagene (n = 3). For 49%, SRT was the first post-CAR T therapy. SRT indications included palliation (n = 72), consolidation (n = 5), bridging to allogeneic transplant (allo; n = 5) or 2nd CAR T (n = 3), and other (n = 33). At SRT, 29 (24%) had localized disease of which 28 were treated comprehensively; overall 37% of SRT was comprehensive. Median dose was 30 Gy (4–50.4). 27% received concurrent systemic therapy. SRT was well tolerated: 8% (n = 10) had ≥ grade 2 (G2) acute adverse events (G3 = 1, no G4/5). Objective response rate was 74% (41% complete) within the SRT field and 38% (22% complete), overall. With a median follow up of 6 mo, 78 patients (64%) progressed. First failure sites were 64% pre-existing/mixed and 38% in field/marginal. For DLBCL patients, median EFS was 4.2 mo in limited stage and 1.2 mo in advanced (p < 0.001). Median OS was 59.6 mo and 3.4 mo in localized and advanced DLBCL relapse (p < 0.001). Median OS for RT as bridging to allo/CAR T, consolidation, and palliation was unreached, 6.7 mo, and 3.0 mo (p < 0.001). Localized relapse and receipt of comprehensive SRT were associated with improved EFS (p < 0.001) while primary refractory disease to CAR T (p = 0.02), elevated LDH pre SRT (p = 0.02), and SRT for palliation (p = 0.03) or for ≥2ndsalvage post CAR T (0.04) were associated with shorter EFS. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cellular therapies, Radiation Therapy Conflicts of interests pertinent to the abstract. C. Ladbury Research funding: Reflexion G. Shah Consultant or advisory role: ArcellX Research funding: Janssen, Amgen, Beyond Spring, BMS M. D. Jain Consultant or advisory role: Kite/Gilead, Novartis, BMS, MyeloidTx Research funding: Kite/Gilead, Incyte S. Dandapani Research funding: Reflexion, Bayer B. S. Imber Honoraria: GT Medical Technologies Inc.

EXPLORING DIFFERENTIAL MUTATIONAL DISTRIBUTION BY TARGETED SEQUENCING IN A R‐CHOP TREATED COHORT OF DIFFUSE LARGE B‐CELL LYMPHOMA PATIENTS

Background: Diffuse large B-cell lymphoma (DLBCL) harbors striking clinical and molecular heterogeneity, which continues to encumber risk stratification with a consequently high rate of refractory/relapsed patients (pts). Though the genomic landscape of DLBCL has been comprehensively uncovered, the search for eligible molecular biomarkers continues. Exploratively, we set out to retrospectively evaluate differential mutational distributions in a DLBCL cohort using targeted sequencing. Patients and method: A cohort of 105 de novo DLBCL pts, uniformly treated with first-line R-CHOP, were studied. Thirty pts relapsed, of which 70% had early relapses (<2 years after completing therapy), while 30% had late relapses (≥2 years). Targeted next-generation sequencing (90 gene panel) was applied on archival paraffin-embedded diagnostic samples and, if available, first relapse samples. Results: In total, 118 samples were sequenced, each displaying a median of 12 (range 1–46) putative somatic protein-coding mutations. Germinal center B-cell (GCB) DLBCL (n = 60) displayed a differential somatic signature with enrichment of EZH2, TNFRSF14, BCL2, ACTB, SOCS1, and FAS mutations (Fisher's Exact, p < 10-4), whereas mutations in CDKN2A, PRDM1, MYD88, and CD79B were significantly enriched in non-GCB pts (p < 10-4, n = 44). Survival analysis confirmed inferior overall survival (OS) in non-GCB DLBCL (5-year OS, log-rank (Mantel-Cox), p = 0.01, hazard ratio (HR) 1.7). Pts with double-hit biology (DHB), defined as either MYC and BCL2 and/or BCL6 fluorescent in situ hybridized positive and/or with MYC and BCL2 immunohistochemical double expression (n = 32), did not display a significant mutational signature or differential OS. However, a subgroup of DHB pts characterized by mutations in MYC, PRDM1, or IRF4 (n = 15) had markedly inferior OS (5-year OS, log-rank, p = 0.0003, HR 3.34) compared to negative non-DHB pts (n = 55) or negative non-DHB/DHB pts (p = 0.0017, HR 2.7, n = 72). Noticeably, ACTB mutations were only present in non-DHB pts. The mutational distribution at diagnosis did not differ between pts with relapse and in sustained remission. However, in the relapse group, GNA13 mutation at diagnosis was more frequent in early relapses than late relapses (43% vs. 0%, Fisher’s Exact without correction, p = 0.03). The presence of GNA13 in the entire cohort showed a trend towards inferior survival. Conclusion: Differential distribution with significant mutational signatures were expectedly found in GCB versus non-GCB, but not in subgroups with DHB or relapse. Interestingly, mutations in MYC, PRDM1 or IRF4 identified a distinct subset of DHB pts with inferior survival. Furthermore, GNA13 mutations were significantly enriched in early relapse pts. These preliminary findings call for validation of GNA13 as a potential marker of early relapse as well as the prognostic value of MYC, PRDM1 and IRF4 mutations in DHB DLBCL. The research was funded by: The Danish Cancer Society and The Vissing Foundation Keywords: aggressive B-cell non-Hodgkin lymphoma, genomics, epigenomics, and other -omics, tumor biology and heterogeneity Conflicts of interests pertinent to the abstract T. S. Larsen Consultant or advisory role Roche, Gilead, Novartis, Celgene/BMS Research funding: Genentech

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

Introduction: Pre-treatment PET/CT scans have not yet been incorporated into risk stratification models despite being the imaging modality of choice in DLBCL. Deep learning computer algorithms have consistently demonstrated the ability to analyze imaging data and identify features that are not readily apparent to the human eye. Therefore, to assess the prognostic performance of pre-treatment PET/CT scans in patients with DLBCL, we compared automatically extracted radiomics features using a convolutional neural network with a standard prognosticating tool (NCCN-IPI). Methods: Native DICOM images from FDG PET/CT scans of newly diagnosed DLBCL patients were preprocessed for regularity and then segmented using the nnU-Net architecture with an external lymphoma-specific model. Feature extraction and SUV characterization were accomplished with PyRadiomics and NiBabel. Our computational method included no manual segmentation correction. Individual radiomics features (n = 115) were evaluated for association with event free survival (EFS) via univariate Cox regression analysis and by Kaplan Meier log rank testing of upper and lower feature quartiles. Additionally, Spearman and Pearson correlation matrices were used to guide feature selection while minimizing collinearity. We then assessed the association of the highest scoring radiomics features with EFS. Results: Radiomics features were automatically extracted from a cohort of 713 newly diagnosed DLBCL patients with pre-treatment PET/CT scans treated at Mayo Clinic between 2003 and 2015 and followed through 2023. Median age at diagnosis was 64 years (range 18–93), 41% were females. NCCN-IPI composition and outcomes of our cohort was comparable to the previously published NCCN cohort, with patient distribution and 5-year OS as follows: Low (11%, 5-y OS 89%), Low-intermediate (42%, 5-y OS 72%), High-intermediate (38%, 5-y OS 53%), High (9%, 5-y OS 25%). Log rank testing found numerous radiomics features were associated with EFS including least axis length (LAL) (HR: 2.83, 95% CI: 2.08–3.84, p < 0.005, Figure A) and volume (HR: 2.47, 95% CI: 1.84–3.01, p < 0.005, Figure B). As a reference, NCCN-IPI univariate Cox regression analysis of EFS produced a Harrell’s C-statistic (c) of 0.633. Single radiomics features of sphericity, volume, surface area, and least axis length individually produced unadjusted c-statistics of 0.624, 0.629, 0.636 and 0.638, respectively. Combinations of radiomics features (surface area + least axis length) demonstrated cumulative benefit (c = 0.642). Keywords: Aggressive B-cell non-Hodgkin lymphoma, PET-CT, Risk Models Conflicts of interests pertinent to the abstract. T. M Habermann Consultant or advisory role: Data Monitoring Committee: Seagen, Tess Therapeutics, Eli Lilly & Co. Scientific Advisory Board: Morpohsys, Incyte, Biegene, Loxo Oncology. No personal compensation is received for these activities, any compensation is received by my institution. Research funding: Genentech, Sorrento, BMS

COORDINATED CHANGES IN THE TUMOR MICROENVIRONMENT (TME) ARE ASSOCIATED WITH INCREASED RISK OF THERAPEUTIC FAILURE IN NEWLY DIAGNOSED DIFFUSE LARGE B‐CELL LYMPHOMA (DLBCL)

Introduction: Despite advances, 20%–40% of patients with DLBCL do not achieve remission or relapse after an initial response. We aimed to identify immunological factors associated with early clinical failure in DLBCL. Methods: Patients with DLBCL treated with rituximab and anthracycline-based chemotherapy were prospectively enrolled in the University of Iowa/Mayo Clinic Lymphoma Specialized Program of Research Excellence (SPORE). Tissue microarrays (TMAs) containing specimens from diagnosis were analyzed using the Digital Spatial Profiling (DSP) system quantifying expression of 58 proteins (Figure 1A). Event-free survival (EFS) was defined as time from diagnosis to relapse, progression, or death from any cause. Patients with EFS of at least 24 months were classified as achieving EFS24. Following normalization, logistic regression was performed on DSP data to adjust for IPI and cell of origin. Multiplex immunofluorescence (MxIF) using the CODEX system was performed on a biopsy specimen from a representative patient. Machine learning models were used for cell segmentation and classification (Figure 1B). Results: Specimens from 446 DLBCL patients were available on TMAs, of which 321 (72%) achieved EFS24. DSP data was acquired in 395 unique DLBCL patients and showed that increased expression of CD163 (Log2FC = 2.9; p = 0.0009), BCL2 (Log2FC = 1.4; p = 0.047), and PDL1 (Log2FC = 1.3; p = 0.05) were significantly associated with increased risk of EFS24 failure (Figure 1A, red arrows). Conversely, increased expression of CD11c (Log2FC = 0.5; p = 0.003), HLA-DR (Log2FC = 0.4; p = 0.01), CD357/GITR (Log2FC = 0.8; p = 0.01), CD137 (Log2FC = 0.7; p = 0.02), and B7H3 (Log2FC = 0.9; p = 0.02) were significantly associated with decreased risk of EFS24 failure (Figure 1A, green arrows). A total of 3004 single cell events were acquired using MxIF, of which 55% were classified as B cells, 17% as T cells, 8% as macrophages, and 20% as other cells. Within B cells, 81% were classified as HLA-DR+, 73% as CD11c+, 54% as BCL2+, while; 45% were positive for all 3 antigens (Figure C1–4). GITR expression was confirmed in 3% of T cells and showed a memory (CD45RO+), activated (CD38+) phenotype (Figure D1–4). The research was funded by: Department of Defense (DOD), Lymphoma Research Foundation (LRF), National Cancer Institute (NCI) Keywords: aggressive B-cell non-Hodgkin lymphoma, genomics, epigenomics, and other -omics, microenvironment No conflicts of interests pertinent to the abstract.

MYC/BCL6 DOUBLE HIT LYMPHOMA NEGATIVE FOR T(3;8) BCL6::MYC FUSION IS ASSOCIATED WITH INFERIOR SURVIVAL, IN CONTRAST WITH T(3;8) POSITIVE PSEUDO‐DOUBLE HIT LYMPHOMA

Introduction: A small proportion of large B cell non-Hodgkin lymphoma (NHL) has MYC and BCL6 rearrangements, detectable by fluorescence in-situ hybridisation (FISH) break-apart probes. There are conflicting reports on the prognosis of this group. A proportion of them have a single t(3;8) BCL6::MYCtranslocation which accounts for both break-apart probe results. The prognostic significance of this t(3;8) positive group is unknown. Methods: We conducted a retrospective cohort study of cases of high grade B NHL, excluding Burkitt lymphoma, referred to a regional histopathology and FISH laboratory from 14 hospitals in the West Midlands, UK. Cases of MYC/BCL2 double-hit lymphoma without BCL6 rearrangement were excluded. Survival was analysed using univariate and multiple regression with Cox proportional hazards. Results: Data were collected for 106 cases of high grade B cell lymphoma with MYC rearrangements. BCL6 rearrangement by FISH break-apart probe (BCL6r) was seen in 61, of which 19/38 tested with a t(3;8) fusion probe were positive. The four groups, MYC single hit, BCL6r t(3;8) positive, BCL6r t(3;8) negative, and BCL6r t(3;8) untested, were well matched for baseline histological and clinical characteristics. Univariate survival analysis showed that the BCL6r t(3;8) negative group had inferior overall survival (OS) and progression-free survival relative to MYC single hit (hazard ratio (HR) 2.6 for death, p = 0.01), and the association was maintained in a multivariate analysis (HR 3.1, p = 0.01). No significant effect on survival was associated with the BCL6r t(3;8) positive group. Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers, pathology and classification of lymphomas No conflicts of interests pertinent to the abstract.

CART‐SIE REAL LIFE STUDY: PRIMARY MEDIASTINAL B‐CELL LYMPHOMA (PMBCL) HAVE A SUPERIOR OUTCOME COMPARED TO LARGE B‐CELL LYMPHOMA (LBCL) TREATED WITH AXICABTAGENE CILOLEUCEL

Introduction: In Italy, axicabtagene ciloleucel (axi-cel) is commercially available for the treatment of LBCL, including diffuse large B-cell lymphoma (DLBCL-NOS), high grade B-cell lymphoma (HGBCL), transformed follicular lymphoma (tFL), and PMBCL patients, relapsed/refractory (R/R) after at least two prior treatments. Methods: The CART-SIE is an ongoing prospective and retrospective study collecting data on the outcome of all consecutive lymphoma patients treated with CAR-T cells. The aim of this analysis was to compare the outcome of PMBCL and LBCL treated with axi-cel in the Italian real life. Results: From 2019 to 2022, 444 patients were infused. Axi-cel was administered in 192 patients: 57 PMBCL and 135 LBCL, including DLBCL-NOS (85), HGBCL (28) and tFL (22), respectively. The clinical characteristics for PMBCL versus LBCL showed: median age 35 versus 56 (p = 0.0001), bulky 33/57 (58%) versus 47/135 (35%) (p = 0.0035), limited stage 35/57 (61%) versus 41/135 (31%) (p = 0.0001), respectively. Median follow-up time for infused patients was 10.99 months (IQR 4.18, 18.03). The Overall Response Rate (ORR, complete CR + partial PR) at 30-days after the infusion was 44/57 (77%) with 30 (53%) CR in PMBCL, and 97/135 (72%) with 67 (50%) CR in LBCL, (p = 0.4206). The 12-months Overall Survival (OS) was 89% (95% CI: 81–98) in PMBCL versus 70% (95% CI: 62–80) in LBCL (log-rank p = 0.0016); by different histology subtypes, the 12-months OS was 89% (95% CI: 81–98) in PMBCL versus 74% (95% CI: 63–86) in DLBCL-NOS, 58% (95% CI: 41–81) in HGBCL, 76% (95% CI: 58–100) in tFL (log-rank p = 0.0013). The 12-months PFS was 65% (95% CI: 53–80) in PMBCL versus 47% (95% CI: 39–57) in LBCL (log-rank p = 0.0160); by different histology subtypes, the 12-months PFS was 65% (95% CI: 53–80) in PMBCL versus 40% (95% CI: 30–54) in DLBCL-NOS, 51% (95% CI: 35–75) in HGBCL, 65% (95% CI: 47–90) in tFL (log-rank p = 0.0420). All grades CRS was observed in 49/57 (86%) PMBCL and 118/135 (87%) LBCL patients, with 9 (16%) and 12 (9%) severe (grade 3–4) CRS, respectively; all grades ICANS were reported in 25 (44%) PMBCL patients and in 46 (34%) LBCL, with 12 (21%) and 14 (10%) severe (grade 3–4) ICANS, respectively. Tocilizumab was administered in 41 (72%) PMBCL and in 90 (67%) LBCL; steroids in 20 (35%) PMBCL and in 36 (27%) LBCL patients. Twelve (21%) PMBCL and 15 (11%) LBCL patients were admitted in the intensive care unit. Treatment related mortality was reported in 3 (5%) PMBCL and 3 (2%) LBCL patients. In a multivariable model with all clinically important and unbalanced variables, PMBCL maintained its significantly superior outcome as compared to LBCL, for OS and for PFS. Conclusions: CART-SIE is the first real-life study comparing the prognosis of patients affected by R/R PMBCL and LBCL treated with axi-cel. PMBCL patients had a superior OS and PFS compared to LBCL, with a similar incidence of CRS and ICANS. Encore Abstract—previously submitted to EHA 2023 Keywords: aggressive B-cell non-Hodgkin lymphoma, cellular therapies Conflicts of interests pertinent to the abstract A. Chiappella Consultant or advisory role: Celgene-BMS, Gilead-Sciences, Ideogen, Janssen, Roche, SecuraBIO, Takeda Other remuneration: Lecture fees/Educational activities: Astrazeneca, Celgene-BMS, Gilead-Sciences, Incyte, Janssen-Cilag, Novartis, Roche, Takeda

BTK INHIBITORS IN CNSL AND HIGH‐RISK/REFRACTORY DLBCL PATIENTS: A REAL‐WORLD STUDY

Objective: The effectiveness and prognosis of a BTki-containing regimen in first-line treatment and relapsed/refractory patients were assessed in this study. Methods: There were 26 patients with DLBCL. BTKi was administered to patients with newly diagnosed, relapsed, refractory primary PCNSL and high-risk/refractory systemic DLBCL, and the effectiveness and PFS were evaluated. Results: The BTKi therapy study included 26 participants (16 PCNSL, 10 DLBCL). Among PCNSL,3 patients who had achieved PR following MTX-based first-line chemotherapy were given BTKi as a monotherapy for disease recurrence. BTKi patients lived for an average of 5 (1–8) months before dying from disease progression, which is 5 months longer than the typical patient survival period following chemotherapy recurrence. After three rounds of MTX-based chemotherapy, none of the six patients with refractory PCNSL achieved PR. After BTKi was utilized as second-line therapy, the average survival time was increased by 12 (2–21) months. Three patients received early treatment, while the remaining three received BTKi after the third round of medicine. Early patients had a longer average survival period than late ones (11 months vs. 10 months). The remaining seven high-risk patients received first-line chemotherapy and BTKi treatment. The median follow-up duration was 5 months, the ORR was 100%, and neither the median PFS nor the median OS were achieved. The mean maintenance time was 8 months. Among 10 patients with DLBCL, 8 of them are high risk group, and 2 had refractory disease. When the disease of two SCNSL patients advanced, BTKi was used in conjunction with chemotherapy as a salvage treatment, and BTKi was kept up for an average of 5 months. The efficacy was evaluated as PD. The ORR was 80% (4/5, 1 case was not assessed) and CR rate was 100% in high risk group. Four of these CNS-IPI high-risk DLBCL patients had adrenal involvement and a high IPI score, with BTKi maintained for an average of 6 months, two of them achieved CR, one of PD, and 1 case was not evaluated. The efficacy evaluation was CR in the other two high-risk CD5+ patients, whose BTKi was sustained for 12 months and 6 months, respectively. After receiving standard chemotherapy, the remaining 2 refractory patients kept getting worse. One patient with hepatitis B cirrhosis had elevated AST and ALT levels after one course of medication, so BTKi was stopped. The other patient was kept on BTKi alone for 4 months, but the efficacy was still PD. Patients with PCNSL have a dismal prognosis, in particular, the average survival time for R/R patients is less than two months. The research was funded by: National Natural Science Foundation of China (8226010026), Natural Science Foundation of Gansu Province (22JR11RA053) Keywords: aggressive B-cell non-Hodgkin lymphoma, molecular targeted therapies, combination therapies No conflicts of interests pertinent to the abstract.

SEVERE HEMATOLOGICAL TOXICITY FOLLOWING CD19 CAR‐T FOR RELAPSED/REFRACTORY LBCL IS ASSOCIATED WITH SUPPRESSIVE IMMUNE DYSREGULATION AND LIMITED CAR‐T EXPANSION

Background: Hematological toxicity represents the most frequent high-grade toxicity of CD19 CAR-T, but remains poorly understood. We recently proposed a classification system for CAR-T-related hematotoxicity, defining three unique phenotypes of neutrophil recovery: quick [“Q”] versus intermittent [“I”] versus aplastic [“A”]. Quick: sustained neutrophil recovery without a second dip below an ANC <1000/µL. Intermittent: neutrophil recovery (ANC > 1500/µL) followed by a second dip with an ANC < 1000/µL after day 21. Aplastic: continuous severe neutropenia (ANC < 500/µL) ≥14 days. Multivariable binary logistic regression was applied to analyze clinical metadata. CAR T-cell expansion dynamics were studied during the first 4 months post-CAR-T infusion. The plasma proteome was explored in 58 patients across four time points (day 0, 4, 14, 28) using a 92-protein multiplex proximity extension assay (Olink Bioscience). Progression-free (PFS) and overall survival (OS) were studied via Kaplan-Meier estimates. Results: The distribution of phenotypes was 18%, 42%, and 40% (A vs. I vs. Q). As expected, ‘aplastic’ patients displayed prolonged severe neutropenia (A vs. I vs. Q: 28 vs. 10 vs. 5 days, p < 0.001) and a higher rate of severe infections (40% vs. 22% vs. 18%). On multivariable regression of baseline risk factors (n = 344), the aplastic phenotype was independently associated with the presence of BM infiltration (p = 0.004), low ANC (p = 0.002), and increased ferritin (p = 0.039). When comparing CAR-T expansion among phenotypes, ‘intermittent’ patients displayed the greatest CAR T-cell expansion over time (Figure 1A). Conversely, ‘aplastic’ patients displayed low expansion with an unfavorable relationship between CAR-T expansion and baseline tumor burden (Figure 1B). Serum proteomics revealed higher markers of T-cell suppression, endothelial dysfunction, inflammatory cytokines, and macrophage activation in the ‘aplastic’ phenotype group (Figure 1C). Notably, both PFS and OS was poor in the ’aplastic’patients (1-yr PFS 26%, 1-yr OS 46%). On the other hand, the ‘intermittent’ phenotype, characterized by recurrent neutrophil dips, was associated with superior survival outcomes (1-yr PFS 51%, 1-yr OS 46%). Keywords: aggressive B-cell non-Hodgkin lymphoma, cellular therapies, basic and translational science – Basic and Translational Science - Other Conflicts of interests pertinent to the abstract K. Rejeski Consultant or advisory role: BMS/CELGENE Honoraria: Novartis, BMS/CELGENE Research funding: Kite/Gilead Travel grants: Kite/Gilead

Prognostic values of circulating TREM2+ and ARG1+ Mreg cells in adults with treatment‐naïve diffuse large B‐cell lymphoma

Introduction: Novel Trem2+ (triggering receptor expressed on myeloid cells 2) and Arg1+ (arginase 1) regulatory myeloid cells (Mreg) that lead to the dysfunction of CD8+ T cells and facilitate tumor growth were recently discovered in a murine cancer model by Yonatan Katzenelenbogen et al. However, as the roles of Mreg cells have never been examined in human cancer patients, we aim to elucidate the clinical impact of circulating Mreg cells on patients with treatment-naive B-cell NHL, especially focusing on DLBCL. Methods: This prospective, observational study enrolled 102 adults with newly diagnosed and treatment-naïve B-cell NHL, including 62 DLBCL, 25 FL (4 grade 3B), 4 MCL, 4 MZL, 2 LPL, 2 BL, and 3 mature B-cell neoplasms, from December 2020 to November 2022. We obtained human circulating TREM2+ and ARG1+ Mreg cells from freshly isolated peripheral blood and calculated their percentages among CD45+ and CD15- cells by flow-cytometry analysis. Non-stain (NS) and fluorescence minus one (FMO) controls were used for gating positive levels of surface TREM2 and intracellular ARG1, respectively. Results: Among 102 patients with B-cell NHL, those with high-risk IPI had significantly higher percentages of circulating Mreg cells than patients with intermediate or low-risk IPI (5.46% vs. 1.71% vs. 0.63%, P H vs. L < 0.001, P H vs. I = 0.032, P I vs. L = 0.005); patients with aggressive subtypes (including grade-3B FL) had significantly higher percentages of circulating Mreg cells than patients with indolent subtypes (1.89% vs. 0.93%, P = 0.023). For 62 DLBCL patients, those with high IPI risk (9.18% vs. 1.25%, P < 0.001), bulky mass ≥ 7.5 cm (5.08% vs. 1.18%, P = 0.057), or DEL (5.13% vs. 1.21%, P = 0.036) had significantly higher percentages of circulating Mreg cells (Figures A–F). More importantly, DLBCL patients with circulating Mreg cells ≥4.5% had significantly worse PFS and OS than those with Mreg cells <4.5% after a median follow-up of 14 months (Figures G and H); when utilizing multivariate Cox regression analysis, “circulating Mreg cells ≥4.5%” remained an independent prognostic factor for both PFS and OS after adjusting for confounding factors, including age, sex, high-risk IPI, bulky mass ≥7.5 cm, BM involvement, non-GCB type, and DEL. The research was funded by: The research was funded by grants from: (1) the Taiwan Ministry of Science and Technology (MOST 111-2314-B-075-037), (2) Taipei Veterans General Hospital (V110B-012), (3) the Chong Hin Loon Memorial Cancer and Biotherapy Research Center, (4) the Melissa Lee Cancer Foundation, and (5) the Taiwan Clinical Oncology Research Foundation. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Diagnostic and Prognostic Biomarkers No conflicts of interests pertinent to the abstract.

REAL‐WORLD OUTCOMES OF INTRAVENOUS IMMUNOGLOBULIN FOR HYPOGAMMAGLOBULINEMIA AFTER CHIMERIC ANTIGEN RECEPTOR T‐CELL THERAPY IN PATIENTS WITH DIFFUSE LARGE B‐CELL LYMPHOMA

Introduction: Chimeric antigen receptor T-cell (CAR-T) therapy is a treatment for patients with diffuse large B-cell lymphoma (DLBCL) and is associated with toxicities, including hypogammaglobulinemia (HGG). Intravenous immunoglobulin (IVIG) is often used to manage HGG and prevent recurrent infections after CAR-T therapy, but more real-world evidence is needed to support this. Aim: To describe the real-world incidence of HGG and the effectiveness of IVIG after CAR-T therapy in patients with DLBCL. Methods: This observational cohort study used de-identified data from the nationwide (US-based) electronic health record (EHR)-derived Flatiron Health database. Patients were aged ≥18 years, diagnosed with DLBCL, had ≥2 visits in the Flatiron network on/after 1-Jan-11 and had received CAR-T therapy (tisagenlecleucel or axicabtagene ciloleucel) in any treatment line after 1-Jan-18. Baseline characteristics were identified in the 60 days prior to the index date (date of first CAR-T therapy administration). Outcomes, including HGG, were measured from index date until patient death or end of data availability (cut-off: 30-Apr-21). In this ad-hoc analysis, the primary objectives were to evaluate HGG incidence and IVIG use in patients with DLBCL who received CAR-T therapy. Exploratory objectives were to describe overall survival (OS) and progression-free survival (PFS) by IVIG treatment. Proportions and medians were used for patient characteristics. The Kaplan–Meier method was used for clinical outcomes. Results: Overall, 91 patients were included. During follow-up, 14 patients (15.4%) developed HGG, of which six cases were ‘directly attributed’ and one case ‘possibly attributed’ to CAR-T therapy; attribution was not documented for seven patients. Among these 14 patients, eight received treatment for HGG and six had no documented record of treatment. In total, 14/91 patients received IVIG (IVIG cohort). The IVIG cohort was younger (median [range] age 59 [32–67] vs 63 [28–83] years), had more females (50.0% vs 37.7%), had more patients with an Eastern Cooperative Oncology Group score of 2 (14.3% vs 6.5%) and was more frequently treated in a community setting (64.3% vs 49.4%) than the non-IVIG cohort. In the IVIG and non-IVIG cohorts, median (95% confidence interval [CI]) OS was not reached (NR; 5.6–NR) and 18.3 (9.1–NR) months, respectively and median (95% CI) PFS was NR (2.3–NR) and 3.0 (2.7–7.4) months, respectively. Conclusions: In this real-world study, half of the 14 HGG cases in patients with DLBCL were directly/possibly attributed to CAR-T therapy. This may be an underestimate because HGG is primarily assessed using laboratory data but here it was identified using EHRs. Despite a small sample size, the hypothesis-generating analyses of IVIG effectiveness and management outcomes support further evaluation of IVIG for the treatment of HGG in patients with DLBCL after CAR-T therapy. The research was funded by: Takeda Development Center Americas, Inc. Writing support was funded by: Takeda Pharmaceuticals International AG. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Immunotherapy Conflicts of interests pertinent to the abstract D. S. Chun Employment or leadership position: Takeda Development Center Americas, Inc. Stock ownership: Takeda Y. Yin Employment or leadership position: Takeda Development Center Americas, Inc. Stock ownership: Takeda C. Anderson-Smits Employment or leadership position: Takeda Development Center Americas, Inc. Stock ownership: Takeda

SGR‐1505‐101: A PHASE 1, OPEN‐LABEL, MULTICENTER, DOSE‐ESCALATION STUDY OF SGR‐1505 AS MONOTHERAPY IN SUBJECTS WITH MATURE B‐CELL MALIGNANCIES

Background: MALT1 (Mucosa-associated lymphoid tissue lymphoma translocation protein 1) is a component of the MALT1-BCL10-CARD11 complex downstream from the Bruton Tyrosine Kinase (BTK) on the B-cell receptor signaling pathway. MALT1 is a key mediator of the nuclear factor kappa B (NF-κB) signaling, which is the main driver of a subset of B-cell lymphomas. MALT1 is considered a potential therapeutic target for several subtypes of non-Hodgkin B-cell lymphomas and chronic lymphocytic leukemia (CLL), including tumors with acquired BTK inhibitor (BTKi) resistance. In particular, constitutive activation of the NF-κB is a molecular hallmark of activated B cell-like diffuse large B cell lymphoma (ABC-DLBCL), and MALT1 may have utility as a treatment option for ABC-DLBCL. SGR-1505 is an oral potent small molecule allosteric inhibitor of MALT1 that inhibits MALT1 enzymatic activity, and demonstrates anti-proliferative activity in ABC-DLBCL cell lines, both BTKi-sensitive (OCI-LY10) and BTKi-resistant (OCI-LY3). SGR-1505 administered as a single agent and in combination with the approved Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib, demonstrates tumorostatic and regressive antitumor activity in ABC-DLBCL cell line-derived xenograft and patient-derived xenograft models. Aims: These data suggest that SGR-1505-mediated MALT1 inhibition has therapeutic potential and may expand therapeutic options for patients with selected B-cell lymphomas supporting further evaluation of SGR-1505 in clinical trials. Methods: SGR-1505-101 (NCT05544019) is a phase 1, multicenter trial of SGR-1505 as monotherapy in subjects with mature B-cell malignancies. At present, the study has been activated in 3 sites in the United States. The primary objective is to evaluate safety and tolerability of SGR-1505 as monotherapy and to identify the maximum tolerated dose (MTD) and/or recommended dose (RD). Secondary objectives are to evaluate the pharmacokinetic (PK) profile, food effect, drug-drug interaction, and preliminary anti-tumor activity of SGR-1505. Key inclusion criteria are: history of mature B-cell malignancy (including aggressive and indolent B-cell lymphomas, Waldenström macroglobulinemia, and CLL); measurable or detectable disease according to the applicable disease-specific classification system (Lugano, iwCLL, WWM6); Eastern Cooperative Oncology Group (ECOG) performance status of ≤2. Patients with indolent B-cell lymphomas or CLL must have an indication for treatment and not require immediate cytoreductive therapy. Subjects with symptomatic or active CNS involvement, and other conditions or laboratory findings placing them at increased risk to the use of an investigational drug are excluded. SGR-1505 is initially dose-escalated using an accelerated titration design in cohorts of 1–6 subjects, and at higher dose levels using a conventional 3+3 design. Encore Abstract—previously submitted to EHA 2023 The research was funded by: Schrodinger Keywords: aggressive B-cell non-Hodgkin lymphoma, molecular targeted therapies, ongoing trials Conflicts of interests pertinent to the abstract. B. Yoo Employment or leadership position: Schrodinger Stock ownership: Schrodinger Z. Nie Employment or leadership position: Schrodinger Stock ownership: Schrodinger G. Krilov Employment or leadership position: Schrodinger Stock ownership: Schrodinger J. Tan Employment or leadership position: Schrodinger Stock ownership: Schrodinger H. Wright Employment or leadership position: Schrodinger Stock ownership: Schrodinger D. Weiss Employment or leadership position: Schrodinger Stock ownership: Schrodinger W. Yin Employment or leadership position: Schrodinger Stock ownership: Schrodinger K. Akinsanya Employment or leadership position: Schrodinger Stock ownership: Schrodinger

EXPLORING THE POTENTIAL CORRELATION BETWEEN NEUTROPHIL EXTRACELLULAR TRAPS AND PROGNOSIS IN PATIENTS WITH DIFFUSE LARGE B‐CELL LYMPHOMA AND HODGKIN’S LYMPHOMA

Introduction: Neutrophil extracellular traps (NETs) are web-like structures of decondensed chromatin and granule proteins that are released from neutrophils in response to infection. NET-release also occurs and contributes to inflammation, organ dysfunction and thrombosis in patients with non-infectious inflammatory conditions, such as cancer. In several solid cancer types, NETs have been associated with poorer prognosis by facilitating tumour growth and metastasis. One study has associated NETs with tumour progression and poorer prognosis in diffuse large B-cell lymphoma (DLBCL), however the knowledge of the role of NETs in lymphoma is sparse. Here, NETs were measured in plasma from patients with DLBCL and Hodgkin’s lymphoma (HL), and correlated to blood counts and clinical outcome of the patients. Methods: Plasma samples from patients with DLBCL (n = 72) and HL (n = 54), diagnosed between 2010 and 2015, were obtained from the Swedish Uppsala Umeå Comprehensive Cancer Consortium (U-CAN) biobank. The lymphoma samples, as well as healthy controls (n = 11), were analysed using a commercial enzyme-linked immunosorbent assay (ELISA) targeting citrullinated histone 3 in complex with externalized DNA, a biomarker considered specific for NETs. Data collected from patient records, including routine blood counts at diagnosis, clinical background and disease outcome, was correlated to the obtained plasma concentrations of NETs. Results: DLBCL and HL patients showed significantly elevated concentrations of NETs in plasma compared to healthy controls (median concentrations 60.07, 65.24 and 5.366 ng/mL, p < 0.0001). In both DLBCL and HL, trends towards better overall survival (p = 0.3308 and 0.0534 respectively) and better progression free survival (p = 0.2777 and 0.1056) were seen for patients with concentrations of NETs above median. While there was no correlation between sex or age and NET levels in DLBCL patients, HL patients under the age of 50 years showed a significant correlation with higher levels of NETs (p = 0.0021). In both DLBCL and HL patients, plasma NET-levels showed a positive correlation with the neutrophil count in blood at diagnosis (p = 0.0087 and 0.0001 respectively). A neutrophil-lymphocyte ratio above 3.0, a known predictor of worse outcome in cancer patients, showed a trend towards being correlated with worse prognosis in DLBCL patients, but this was less evident for HL patients. Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers, Hodgkin lymphoma No conflicts of interests pertinent to the abstract.

SUNMO: A phase III trial evaluating the efficacy and safety of mosunetuzumab in combination with polatuzumab vedotin vs rituximab plus gemcitabine and oxaliplatin in patients with relapsed/refractory aggressive B-cell non-Hodgkin lymphoma.

TPS7586 Background: Aggressive non-Hodgkin lymphomas (aNHL) are a diverse group of neoplasms, of which diffuse large B-cell lymphoma (DLBCL) is the most common subtype (Thandra, 2021). Patients (pts) with relapsed/refractory (R/R) DLBCL after one prior therapy who are unable to receive, or relapse after an autologous stem cell transplant (ASCT) and/or chimeric antigen receptor T-cell therapy have a poor prognosis (Salles, 2019; Di Blasi, 2022). Mosunetuzumab (Mosun) is an off-the-shelf CD20xCD3 T-cell engaging bispecific antibody that redirects T cells to eliminate malignant B cells (Sun, 2015), with promising efficacy and safety as a single agent, as shown in a Phase I trial in pts with B-cell NHL, including aNHL (Budde, 2022). Mosun has also shown promising safety and efficacy in combination with polatuzumab vedotin (Pola), a CD79b targeted antibody-drug conjugate that delivers the microtubule-disrupting agent monomethyl auristatin E directly to B cells (Dornan, 2009), in a Phase Ib/II trial in pts with R/R aNHL (Budde, ASH 2021). Methods: SUNMO (NCT05171647) is a randomized, open-label, global Phase III trial evaluating the efficacy and safety of subcutaneous Mosun + intravenous (IV) Pola (M-Pola) vs IV rituximab + gemcitabine and oxaliplatin (R-GemOx) in pts with R/R aNHL. Eligible pts have CD20-positive R/R aNHL (DLBCL not otherwise specified [NOS], high-grade B-cell lymphoma double/triple hit or NOS, transformed follicular lymphoma [trFL], or Grade 3B FL), ECOG performance status 0–2, and ≥1 prior systemic therapy (if only one prior line of therapy, pts must be ineligible for ASCT). Exclusion criteria include prior treatment with CD20-directed bispecific antibodies, R-GemOx, or GemOx; prior allogeneic stem cell transplant; and any central nervous system involvement of lymphoma. Pts will be randomized 2:1, stratified by the number of prior lines of therapy (1 vs &gt; 1) and response to last therapy (relapsed vs refractory) to receive M-Pola or R-GemOx IV for a fixed duration of up to 8 cycles (6 cycles for Pola; M-Pola, 21-day cycles; R-GemOx, 14-day cycles). The primary endpoint is progression-free survival (PFS) determined by an independent review facility (IRF). Secondary endpoints include overall survival; IRF- and investigator (INV)-assessed complete response (CR) rate, objective response rate, and duration of response/CR; INV-assessed PFS; patient-reported outcomes; and safety. Biomarker analyses include pre-specified prognostic subsets from baseline biopsies and circulating tumor DNA at baseline and during treatment. Enrollment is ongoing, and an estimated 75 sites globally will enroll approximately 222 pts (M-Pola, 148 pts; R-GemOx, 74 pts). Clinical trial information: NCT05171647 .

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

Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most common type of malignant lymphoma, which accounts for approximately 30%–40% of all cases of non-Hodgkin lymphoma (NHL). Although 60% of patients can be cured by standard R-CHOP (rituximab plus cyclophosphamide, doxoru bicin, vincristine, and prednisone) as frontline therapy, patients with resistance to primary chemoimmunotherapy have a poor prognosis. It has been well demonstrated that TP53mutations and PD-L1 expression correlate with therapeutic resistance. Accordingly, in our preliminary observation, we found that sintilizumab (a PD-1 inhibitor) exerts remarkable efficacy and acceptable tolerance in PD-L1 expressing patients with relapsed or refractory (R/R) DLBCL. Therefore, we further initiate a clinical trial to investigate if sintilizumab can enhance the efficacy of R-CHOP in untreated DLBCL patients with TP53 mutations and PD-L1 expression. Methods: This randomized, multicenter study performs in at least 10 clinical sites in China. Patients aged 18 years or older with histologically diagnosed with DLBCL, untreated and a baseline Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 are eligible for inclusion. Patients will receive one cycle of R-CHOP regimen and TP53 status and PD-L1 expression will be examined by PCR and immunohistochemistry (IHC), respectively. Afterwards, patients with TP53 mutations and PD-L1 expression (≥30% by IHC) are randomly assigned (1:1) to receive either sintilimab plus R-CHOP regimen (group A) or R-CHOP only (group B) for 5 cycles, until disease progression, unacceptable toxicity or withdrawal of consent. To avoid the interference of prednisolone, sintilizumab (200mg, every 3 weeks) is administered intravenously at day 10 after chemotherapy. Patients achieving CR in group A will continue to receive sintilizumab for 8 cycles. The primary endpoint of this study is complete response rate (CR) according to Lugano classification. Secondary endpoints include objective response rate (ORR) and 1-year progression free survival (PFS). Tumor measurements are assessed by PET/CT at baseline, at weeks 9 and 18, and then by CT scan every 3 months for 1 year. In addition, blood circulating tumor DNA (ctDNA) and PD-L1 are also under evaluation accordingly. Safety was assessed in all treated patients. The study is registered with www.chictr.org, NCT05280626 and is ongoing. Keywords: aggressive B-cell non-Hodgkin lymphoma, combination therapies, ongoing trials No conflicts of interests pertinent to the abstract.

A SINGLE‐CELL ATLAS OF DIFFUSE LARGE B CELL LYMPHOMA

Diffuse large B-cell lymphoma (DLBCL) is one of the most common yet aggressive types of B-cell lymphoma and remains incurable in 40% of patients. Herein, we profiled the transcriptomes of 94,324 cells from 17 DLBCLs and 3 control samples using single-cell RNA-sequencing technology, creating a comprehensive single-cell map for tumor and infiltrating immune cells for DLBCL. High degrees of inter- and intratumor heterogeneity were revealed, and we identified 73 gene expression programs expressed in malignant B cells. We further characterized 8 nonmalignant B-cell subclusters and 16 T-cell subclusters from the tumor microenvironment. Six myeloid subclusters were also identified, including the LAMP3+ DC subcluster enriched in ABC-DLBCL. More than 2000 likely cell-cell interactions were further predicted in DLBCL, illustrating a complex and highly dynamic DLBCL tumor microenvironment. Unique to B cell lymphomas, a strong costimulatory CD70-CD27 interaction was predicted between malignant cells and T cells. Furthermore, coinhibitory signals mediated by TIM-3 or TIGIT seemed to be the main driving force for T-cell exhaustion. Finally, we discovered that chronic hepatitis B virus infection may have a significant impact on tumor cell survival and immune evasion in DLBCL. Our results provide new insights into B-cell lymphomagenesis and may facilitate the design of targeted immunotherapy strategies. The research was funded by: Swedish Cancer Society, STINT, CIMED, Radiumhemmet, the Swedish Research Council, and the Knut and Alice Wallenberg Foundation, the Guangdong Enterprise Key Laboratory of Human Disease Genomics, the Shenzhen Key Laboratory of Single-Cell Omics Keywords: aggressive B-cell non-Hodgkin lymphoma, genomics, epigenomics, and other -omics, tumor biology and heterogeneity No conflicts of interests pertinent to the abstract.

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

Introduction: N6-methyladenosine (m6A) is the most abundant form of chemical modification in eukaryotes. m6A methylation is dynamically modulated by diverse types of regulators, including methyltransferases (‘writers’), RNA binding proteins (‘readers’), and demethylases (‘erasers’). Growing evidence has shown that m6A methylation plays an essential role in the development and progression of multiple cancers. However, the functions of m6A methyltransferase KIAA1429 in diffuse large B-cell lymphoma (DLBCL) remain undefined. Here, we aimed to unravel an epitranscriptomic mechanism mediated by the m6A methyltransferase KIAA1429 in DLBCL. Methods: Collecting lymph node biopsy samples from 60 de novo DLBCL patients and 20 reactive hyperplasia cases after informed consent. The biological function of KIAA1429 was evaluated using CRISPR/Cas9 mediated genomic deletion and CRISPR/dCas9-VP64 activation. RNA-seq, MeRIP-seq, RIP assays, luciferase activity assay, RNA stability experiments, and co-immunoprecipitation were performed to explore the regulatory mechanism of KIAA1429 in DLBCL. DLBCL cells were subcutaneously injected into SCID-Beige mice to establish xenograft models. The Institutional Animal Care guidelines were followed during the animal experiments. Results: m6A regulators were dysregulated in DLBCL, and a predictive model based on m6A score was developed. KIAA1429 expression was found to be elevated and associated with poor prognosis. KIAA1429 knockout inhibited DLBCL cell proliferation, induced cell cycle arrest in the G2/M phase, promoted apoptosis in vitro, and repressed tumor growth in vivo. Furthermore, KIAA1429 mediated m6A modification of CHST11 mRNA and recruited YTHDF2 to reduce the stability and expression of CHST11. By decreasing MOB1B expression, CHST11 inhibited Hippo-YAP signaling, reprogramming the expression of Hippo target genes (Figure 1). Conclusions: In summary, we identified for the first time that m6A methylation regulators were dysregulated, and its risk score could exert as an independent prognostic indicator in DLBCL. More importantly, our study identified a novel mechanism in which KIAA1429/YTHDF2-coupled epitranscriptional repression of CHST11 inactivates the Hippo-YAP pathway in DLBCL, highlighting the potential of KIAA1429 as a novel predictive biomarker and therapeutic target for DLBCL progression. Keywords: aggressive B-cell non-Hodgkin lymphoma, bioinformatics, computational and systems biology, 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: THRLBCL is an orphan entity of large B-cell lymphomas (LBCL). It is dominated by stromal and immune components—especially T-cells and histiocytes—with similarities to nodular lymphocyte-predominant Hodgkin lymphoma. This microenvironment can produce immunomodulating molecules with therapeutic implications since recent reports suggest THRLBCL resistance to chimeric antigen receptor T-cells (CART). As CART-based therapies are challenging the role of autoHCT as second line consolidation for relapsed/refractory LBCL, we aimed to study the efficacy of autoHCT in THRLBCL in comparison with diffuse LBCL not other specified (DLBCL). Methods: Eligible for this EBMT registry analysis were adult patients who underwent a first autoHCT for THRLBCL between 2016 and 2020. These were compared to adult patients with DLBCL who received a first autoHCT during the same time period. Statistical analysis was descriptive and employed univariate and multivariate comparisons for the impact of baseline characteristics on survival endpoints. A 1:2 matching comparison was performed to better adjust for baseline differences between THRLBCL and DLBCL, respectively. Results: In total 11,151 patients (10,831 DLBCL, 320 THRLBCL) were identified. THRLBCL patients were younger (52 vs. 58 years), predominantly male (76% vs. 59%), had better performance status (ECOG 0: 97% vs. 92%) and less comorbidity (HCT-CI 0: 78% vs. 68%), and had a longer time from diagnosis to transplant (13 vs. 11 months) than DLBCL patients. In contrast, there were no significant differences regarding the proportion of patients receiving autoHCT during second-line (2L) treatment (87% vs. 82%) and sensitive disease status at autoHCT (95% vs. 92%) between THRLBCL and DLBCL, respectively. On logrank comparisons including all patients, THRLBCL was associated with a better 2-year overall survival (OS; 79% vs. 73%; p = 0.05) and progression-free survival (PFS; 72% vs. 61%) than DLBCL. However, when comparing 139 THRLBCL with 278 DLBCL patients matched for age, sex, disease status, performance status (PS), comorbidities (HCT-CI), and time from diagnosis, the outcome differences were no longer significant. Multivariate analyses adjusting for age, gender, disease status, PS, HCT-CI, and time from diagnosis identified higher age, refractory disease, >12 months from diagnosis, and poorer PS as significant risk factors for reduced OS and PFS. Of note, diagnosis THRLBCL was an independent predictor of reduced relapse risk (HR 0.73; p = 0.04). Conclusions: AutoHCT is an effective salvage therapy for relapsed/refractory THRLBCL sensitive to salvage therapy. Superior outcome of autoHCT for THRLBCL compared to DLBCL may be partly explained by more favorable baseline features of the THRLBCL group in terms of age, and PS. The 72% PFS-benchmark shown for autoHCT here has to be considered when deciding about 2L treatment strategies for THRLBCL. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Stem Cell Transplant Conflicts of interests pertinent to the abstract. S. Renders Honoraria: Gilead P. Dreger Honoraria: Novartis, Kite, BMS, Miltenyi

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

Patients with clinical suspect of lymphoma require prompt and correct diagnosis through the histological examination. The aim of this study was to evaluate the reliability and safety of the front-line ultrasonography guided core needle biopsy (UG-CNB) of suspected lymphadenopathies in a large series of patients from 4 southern Italian clinical units. Inclusion criteria were: (i) lymphadenopathy power Doppler ultrasonography retrospectively assessment on recorded video clips and/or images; (ii) 16-gauge CNB with powered automatic suction and 1.6 mm needle diameter sample; (iii) availability of lymph node sections fixed in formalin and embedded in paraffin; (iv) morphological and immunohistochemical information (assessed retrospectively by haematopathologists); and (v) information of an accepted diagnostic reference standard (either the lymphadenopathy surgical resection or follow-up assessment with 2-deoxy-2[F-18] fluoro-D-glucose positron emission tomography [FDG PET]-computed tomography [CT] showing decreased FDG uptake and/or decreased size after specific antineoplastic treatment according to the histological subtype, as well as spontaneous regression for the benign conditions). We retrospectively collected the data of 1048 patients who underwent UG-CNB between 1 July 2009 and 1 January 2022 for suspected pathological lymphadenopathies. In total, out of the 1000 UG-CNBs yielding macroscopically adequate material for histological diagnosis, the 90% (n = 900) resulted in lymph-nodes positive for malignancy. Most patients were suffering from lymphomas (aggressive B-cell non-Hodgkin lymphoma [aBc-NHL], 309 cases; indolent B-cell [iBc]-NHL, 266 cases; Hodgkin lymphoma [HL], 198 cases; and nodal peripheral T-cell [NPTC]-NHL, 27 cases) and 100 cases from metastatic carcinoma; 70 patients were negative for malignancy (diagnosis of atypical lymphadenopathies mimicking lymphomas [ALML]). The remaining 3% were inconclusive at CNB: the morphologic, immunohistochemical and/or molecular investigations did not allow a final diagnosis. Keyword: imaging and early detection No conflicts of interests pertinent to the abstract.