Aggressive B-cell Lymphoma Research Articles

Round-robin testing for LMO2 and MYC as immunohistochemical markers to screen MYC rearrangements in aggressive large B-cell lymphoma

Aggressive large B-cell lymphomas (aLBCL) include a heterogeneous group of lymphomas with diverse biological features. One of the approaches to the diagnosis of aLBCL is based on the identification of MYC rearrangements (MYC-R), in addition to BCL2 and BCL6 rearrangements by genetic techniques, mainly fluorescent in situ hybridization (FISH). Because of the low incidence of MYC-R, the identification of useful immunohistochemistry markers to select cases for MYC FISH testing may be useful in daily practice. In a previous work, we identified a strong association between the profile CD10 positive/LMO2 negative expression and the presence of MYC-R in aLBCL and obtained good intralaboratory reproducibility. In this study, we wanted to evaluate external reproducibility. To evaluate whether LMO2 can be a reproducible marker between observers 50 aLBCL cases were circulated among 7 hematopathologists of 5 hospitals. Fleiss’ kappa index for LMO2 and MYC were 0.87 and 0.70, respectively, indicating high agreement between observers. In addition, during 2021–2022, the enrolled centers included LMO2 in their diagnostic panels to evaluate prospectively the utility of the marker, and 213 cases were analyzed. Comparing LMO2 with MYC, the group of CD10 positive cases showed higher specificity (86% vs 79%), positive predictive value (66% vs 58%), likelihood positive value (5.47 vs 3.78), and accuracy (83% vs 79%), whereas the negative predictive values remained similar (90% vs 91%). These findings place LMO2 as a useful and reproducible marker to screen MYC-R in aLBCL.

Incidence of Burkitt lymphoma in the United States during 2000 to 2019.

Burkitt lymphoma (BL) is an aggressive B-cell lymphoma that occurs worldwide. A study of BL in the US National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program during 1973 to 2005 (n = 3043) revealed three age-specific incidence peaks of BL and rates that were rising. We studied BL cases diagnosed in SEER 22 during 2000 to 2019 (n = 11 626) to investigate age-specific BL incidence rates and temporal trends. The age-standardized BL incidence rate was 3.96/million person-years, with a 2.85:1 male-to-female ratio. The BL rate among both Hispanic and White individuals was higher than in Black individuals (4.52, 4.12 vs 3.14). Age-specific BL rates showed peaks during pediatric, adult and elderly years in males and pediatric and elderly peaks in females. Based on 4524 BL cases with HIV status (SEER 13), only one peak in adult males (45 years) was observed. Overall age-standardized BL incidence rates rose 1.2%/year (not significant) up to 2009 then fell significantly by 2.4%/year thereafter. Temporal trends in BL rates during 2000 to 2019 varied with age group as pediatric BL rates rose 1.1%/year, while elderly BL rates fell 1.7%/year and adult BL rates rose 3.4%/year until 2007 before falling 3.1%/year thereafter. Overall survival from BL was 64% at 2 years, being highest in pediatric patients and lowest in Black and elderly individuals vs other subgroups. Survival improved by 20% between 2000 and 2019. Our data suggest that BL age-specific incidence rates are multimodal and that overall BL rates rose up to 2009 and then fell, suggesting changes in etiological factors or diagnosis.

Real-world Experience of Approved Chimeric Antigen Receptor T-cell Therapies Compared to Clinical Trials Data.

Real-world Experience of Approved Chimeric Antigen Receptor T-cell Therapies Compared to Clinical Trials Data.

Immunomodulatory AVM0703 enhances R-CHOP anti-lymphoma effect with reduced toxicity: Immune-resistant, aggressive A20 lymphoma model.

e14583 Background: Rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone (RCHOP) is the standard of care for most aggressive B-cell lymphomas. RCHOP requires numerous treatment cycles, typically 6, with challenging side effects, including toxicity and long-term secondary malignancies. Trials have demonstrated that 4 cycles of RCHOP was non-inferior to 6 with similar secondary malignancies, however, real world experience has demonstrated that long term outcomes are superior when patients achieve minimal residual disease negative (MRD-) status after the 3rd cycle (1,2). Addition of a novel agent to RCHOP that could reduce the number of cycles to 3 while maintaining response, could overcome the long-term side-effects and allow frail and elderly patients to receive full dose RCHOP in each cycle to improve outcomes. For example, addition of Lenalidomide with RCHOP improved outcomes in ABC-DLBCL patients (3), but leads to therapy related myeloid neoplasm in recent studies (4). AVM0703, an immunomodulatory drug, mobilizes bispecific and i-TCR double-positive NKT cells (AVM_NKT). In the aggressive, immune resistant A20 mouse lymphoma model, neoadjuvant AVM0703 was additive/synergistic, when cyclophosphamide/fludarabine (CyFlu) was dosed 3 + 24 hours later, with no additional toxicities. Therefore, we hypothesized that combining AVM0703 with RCHOP would be an effective and well tolerated treatment of DLBCL. Methods: Tumor-bearing mice were made by sc flank injection of 2x106 murine A20 B-cells in 10-week-old Balb/c mice. When tumor size reached established ~100 mm3, 48 mice (1:1 male: female) were randomized (12 mice each cohort) 1) Placebo 2) 1 cycle RCHOP 3) AVM0703 (18mg/kg HED) 4) AVM0703+1 cycle RCHOP combination treated as described previously (5,6). When Placebo tumors reached ~ 2000 mm3, all mice were sacrificed and tumors, blood, spleen, bone marrow were analyzed for the presence of remnant A20, and immune cell state by flow cytometer. Results: One RCHOP only mouse died from the chemo. There were no deaths in AVM0703+RCHOP group. Tumor remnant live A20 were significantly reduced in all 3 treatment groups compared to Placebo. Interestingly, AVM0703+RCHOP significantly increased the number of MRD- A20 tumors compared to RCHOP alone. Conclusions: Based on this study we plan to determine whether 3 cycles of AVM0703+RCHOP can induce long term CR and if AVM0703 could replace R and reduce long term side effects. 1) Poeschel Lancet 2019. 2) Spurgeon J Natl Canc Inst 2016. 3) Nowakowski JCO 2021. 4) Sperling Blood 2022. 5) Bascuas J Transl Med 2016. 6) Bongard PLoS Pathog 2019. [Table: see text]

Neurotoxicity in patients with CNS lymphomas treated with CAR‐T cell therapy. A LOC network study

Introduction: CAR-T cell therapy represents one of the major progress of the last years in aggressive B-cell lymphomas. Its use in central nervous system (CNS) lymphomas has been limited due to the fear of neurotoxicity but several recent studies have showed promising efficacy in this setting. The aim of this study was to focus on neurotoxicity in CNS lymphoma patients treated with CAR-T cells. Methods: Patients with isolated CNS relapse of DLBCL treated with commercial CAR-T cells at Pitié-Salpêtrière hospital were retrospectively selected. We considered only neurological deterioration for which other causes than CAR-T cell toxicity had been reasonably ruled out. Results: Thirty patients (median age: 65, 17 women, 19 primary, 11 secondary CNS lymphomas, median of 3 previous lines) received CAR-T cells (Tisa-cel: N = 23, axi-cel, N = 7) between May 2020 and December 2022. At the time of CAR-T, 15 (50%) had stable or progressive disease, median Karnofsky Performance Status (KPS) was 70, median Montreal Cognitive Assessment (MoCA) score was 22 and median immune effector cell-associated encephalopathy (ICE) score was 10. Twelve (40%) patients didn’t experience any neurotoxicity after CAR-T, whereas 9 (30%), 3 (10%), 2 (7%), 4 (13%) patients experienced grade 1, 2, 3 or 4 toxicity according to ASTCT classification. The signs of neurotoxicity began at a median of 5 days after CAR-T. The most common symptoms were cognitive disorders (N = 18), motor deficit (N = 4), balance disorders (N = 8), consciousness disorders (N = 5), seizures (N = 3) and movement disorders (N = 3). Among cognitive symptoms, there was predominantly a worsening of pre-existing symptoms regarding memory impairment (12/15 patients) or dysexecutive syndrome (11/13), while dysgraphia or dyscalculia were most frequently new symptoms (in 14/15 and 7/11 patients). Brain MRI showed pseudo-progression in 4 cases. On lumbar puncture, median IL-6 level and median cellularity were higher in patients with grade 2 to 4 neurotoxicity compared to other patients (243 vs. 41 pg/ml, 15 vs. 3 cells/mm3). We found no association between risk of neurotoxicity and age, gender, pre-CART KPS, MoCA or ICE score, primary vs. secondary CNS lymphoma or type of CAR-T. Twelve patients (40%) received steroids, for a median of 10 days, leading to an improvement in a median of 5 days; one received anakinra. Median duration with neurological impairment was 13 days, but was >3 months in 3 patients, including one who finally died from neurotoxicity. Conclusions: The majority of CNS lymphoma patients didn’t experience severe neurotoxicity following CAR-T cells, so that this treatment shouldn’t be contraindicated in this population. However, the percentage of severe and prolonged neurotoxicity is probably higher than in systemic lymphomas and a close neurological follow-up is warranted in these complex situations. Further studies are needed to better predict severe neurotoxicity. Keyword: Cellular therapies Conflicts of interests pertinent to the abstract. S. Choquet Consultant or advisory role: Kite-Gilead, Novartis

CHARACTERISTICS AND TREATMENT OUTCOMES OF AGGRESSIVE HIGH GRADE B CELL LYMPHOMA WITH MYC AND BCL 6 REARRANGEMENTS

According to the International Consensus Classification of Lymphomas (Blood 2022: 140: 1229–53), a new provisional entity high grade B cell lymphoma with MYC and BCL 6 rearrangements (HGBCL-DH-BCL6) was introduced. HGBCL-DH-BCL6 occurred very rare, in less than 10% of patients with HGBCL with rearrangements. Here we assessed clinicopathological features and treatment outcomes of HGBCL-DH-BCL6. We retrospectively collected clinic-pathological data of patients with HGBCL with MYC/BLC6-rearrangements. All cases were evaluated by histopathological/immunohistochemical/flow-cytometry examination (IHC/FCM), with a broad panel of antibodies, including CD10/CD38/ MYC/LMO2/ BCL2/BCL6. Gene status (MYC/BCL2/BCL6) was examined using fluorescence in situ hybridization (FISH), karyotype was successfully achieved in 70% of patients. We identified 18 patients with MYC-rearrangement (median MYC-R: 49% of examined cells; range: 5%–93%), and BCL6-rearrangements (median BCL6-R: 50% of examined cells; range: 5%–93%) with no BCL2- rearrangements was found. Expression of MYC-protein was found only in 22% of patients. Eleven and seven patients, respectively, had DLBCL and BCL-u morphology. Median age at diagnosis was 57 years (range: 18–84). Advanced stage, extranodal disease, increased dehydrogenase lactate were found in 78%, 33%, 83% of patients, respectively. Only 15 patients received immunochemotherapy: 8 were treated with R-CHOP and CNS prophylaxis, other 7 patients had more intensive therapy: GMALL, CODOX/IVAC or DAEPOCH-R. Six patients had consolidative auto-SCT. Morphology of disease, age and intensity of immunochemotherapy had no impact on response and survival. Only 36% of patients achieved complete remission. Median overall survival (OS) and progression free survival (PFS) were 5.6 months and 3.0 months, respectively. OS and PFS for 1 year were 34% and 28% respectively. Actually, 4 patients are alive with no active disease. HGBCL-DH-BCL6 is a rare and aggressive B-cell lymphoma, often without the IHC-protein MYC deletion, with advanced disease presenting at diagnosis. The outcomes is poor and less than 40% of patient are alive from one year from diagnosis. Intensive therapy has not improved treatment results. Keywords: aggressive B-cell non-Hodgkin lymphoma, pathology and classification of lymphomas No conflicts of interests pertinent to the abstract.

OUTCOMES OF THE TREATMENT AFTER ANTI‐CD19 CAR‐T THERAPY FAILURE IN PATIENTS WITH AGGRESSIVE B‐CELL LYMPHOMA—ANALYSIS OF DATA FROM THE CZECH REPUBLIC

Introduction: In patients with aggressive B-cell lymphomas (BCL), the long-term progression-free survival (PFS) after anti-CD19 CAR-T therapy is around 30-40%. The prognosis of patients with progression/relapse after this therapy is poor. There are currently limited data on treatment approaches to improve the prognosis of this group of patients (p) and optimal management is not yet defined. Based on the published data, it seems that some of the new drugs being tested in clinical trials (polatuzumab vedotin, bispecific antibodies, lenalidomide, tafasitamab, selinexor, loncastuximab tesirine) could be used as a "bridge" to allogeneic transplantation, which remains a potentially curative treatment option for some of these patients. Methods: We analyzed patients with aggressive BCL (diffuse large B-cell lymphoma /DLBCL/ – 64p, transformed DLBCL – 19p, high-grade BCL – 12p and primary mediastinal large BCL – 11p) who were treated with anti-CD19 CAR-T cells (tisagenlecleucel 79p and axicabtagene ciloleucel 27p) between Dec 2019 and Dec 2022. This is a multicentre retrospective analysis from 5 university hematological centres, where the patients were referred for CAR-T therapy after ≥ 2 lines of treatment failure from the Czech Republic and Slovakia. We focused on the group of patients who did not respond to this treatment. Results: 106p were treated with anti-CD19 CAR-T therapy. The median follow-up (FU) was 16.4 months. The median PFS and overall survival (OS) were 4.3 and 26.4 months. The overall response rate (ORR) was observed in 63p (60%) with 52% complete response (CR). We further analyzed subsequent therapy in a subgroup of 60p who did not respond to CAR-T treatment (progression in 37p/stable disease in 6p) or had relapse (9p) or progression (8p) after initial response (CR/partial remission). The median FU for failed patients was 9.5 months. Overall, 42p in our cohort received therapy; 18p rapidly progressed and were not treated. 4p were treated with radiotherapy (2p achieved CR) and 38p with systemic therapy (glucocorticoids – 6p, lenalidomide+-rituximab – 6p, chemotherapy+-rituximab – 16p, polatuzumab+bendamustine and rituximab – 6p, CAR-T reinfusion – 2p, other 2p). The ORR after systemic therapy was observed in 17% of patients. Patients who were not treated had more likely massive involvement > 5cm at the time of apheresis (p = 0.02). Of the 60p with CAR-T treatment failure, 39p (65%) died. Median OS for CAR-T therapy failed patients (n=60) was 3.1 months from diagnosis of progression/relapse after CAR-T treatment (6-month and 1-year OS 34.9% and 26%). The median OS were 4.7 for treated and 0.2 months for untreated patients from diagnosis of progression/relapse after CAR-T. The research was funded by: This work was supported by grant AZV NU21-03-00411 from the Ministry of Health of the Czech Republic, by the Cooperatio Program, research area "Oncology and Haematology and by MH CZ – DRO (UHHK, 00179906) Keywords: Aggressive B-cell non-Hodgkin lymphoma, Cellular therapies Conflicts of interests pertinent to the abstract A. Sýkorová Consultant or advisory role GILEAD, NOVARTIS K. Polgárová Consultant or advisory role GILEAD SCIENCES, NOVARTIS Honoraria: NOVARTIS GILEAD SCIENCES Educational grants: GILEAD SCIENCES F. Folber Consultant or advisory role NOVARTIS, GILEAD SCIENCES K. Steinerová Educational grants: GILEAD SCIENCES D. Belada Honoraria: GILEAD SCIENCES, NOVARTIS Educational grants: GILEAD SCIENCES M. Trněný Consultant or advisory role GILEAD SCIENCES, NOVARTIS Honoraria: GILEAD SCIENCES, NOVARTIS Educational grants: GILEAD SCIENCES R. Pytlík Consultant or advisory role GILEAD SCIENCES, NOVARTIS Educational grants: GILEAD SCIENCES, NOVARTIS

MRD‐NEGATIVITY AFTER FRONTLINE DLBCL THERAPY: POOLED ANALYSIS OF 6 CLINICAL TRIALS

MRD‐NEGATIVITY AFTER FRONTLINE DLBCL THERAPY: POOLED ANALYSIS OF 6 CLINICAL TRIALS

What is new about primary cutaneous B cell lymphomas.

Primary cutaneous B-cell lymphomas (CBCL) are a heterogeneous group of B-cell lymphomas without evidence of extracutaneous disease at the time of diagnosis. The 2022 World Health Organization classification of mature lymphoid neoplasms differentiates the indolent primary cutaneous marginal zone lymphoproliferative disorder, primary cutaneous follicle center lymphoma and Epstein-Barr virus-positive mucocutaneous ulcer, from the more aggressive primary cutaneous diffuse large B-cell lymphoma, leg-type and intravascular large B-cell lymphoma. The new updates in the 2022 classification are based on recent scientific advances in the understanding and characterization of these entities. This article aims to review the main clinical, cellular and molecular features of the five CBCL subsets along with their management and treatment. The exponentially growing evidence for new treatment options for systemic B-cell lymphomas raises expectations for the field of CBCL as well. However, specific prospective high quality research on CBCL is still crucial to further define their management and update international guidelines.

Subgrouping of Burkitt lymphoma variants by DNA methylation is driven by an EBV‐associated epigenotype

Introduction: Burkitt lymphoma (BL) is an aggressive mature B-cell lymphoma, which traditionally has been separated into three epidemiologic variants: endemic (eBL), sporadic (sBL) and immunodeficiency-associated BL (iBL). This subgrouping is strongly confounded by EBV-infection. Indeed, there is evidence from molecular studies that subtyping of BL based on EBV status might better reflect the pathogenetic heterogeneity than epidemiology. As EBV is known to influence epigenetic regulation, we here aimed at a comparative DNA methylation (DNAme) profiling of BL variants with respect to their geographic origin and EBV status. Methods: We collected DNAme profiles (Infinium HumanMethylation450 and Infinium MethylationEPIC BeadChip) of 116 BL patients (80 sBL: 7 EBV+; 29 eBL: 27 EBV+; 7 iBL: 4 EBV+), 17 BL cell lines and 6 EBV-transformed LCLs. For group determination unsupervised clustering algorithms (K-means, PGMRA, UMAP) were applied. To investigate potential consequences of EBV-associated DNAme we performed a protein-protein interaction network analysis on genes within the EBV-specific DNAme pattern. Moreover, we mined gene expression values from RNAseq in 21 EBV- sBL and 5 germinal-center B-cell populations. Results: Unsupervised clustering algorithms revealed two distinct DNAme phenotypes, which differentiate EBV+ and EBV- BL based on 1,266 CpGs. This separation is accompanied by a characteristic hypermethylation in EBV+ BLs. Additionally, we identified a subgroup of EBV+ BL with a similar DNAme pattern like the LCLs, possibly indicating latency phase differences within EBV+ BLs. Investigation of the EBV-specific DNAme pattern revealed a network with UBC as a key interactor, indicating the potential importance of the ubiquitin-proteasome system (UPS) in EBV-induced lymphomagenesis. Among genes differentially methylated between EBV+ and EBV- BL, 19 genes have been reported as recurrently mutated in BL. All except 3 of these genes are expressed in sBL and germinal-center B-cells. All these genes were significantly hypermethylated within regulatory regions in EBV+ BLs (σ/σmax = 0.4, q ≤ 0.01), including genes with a lower mutational frequency in EBV+ versus EBV- BLs. Conclusion: The findings of this study show the EBV status to be strongly associated with DNAme subgroups in BL, supporting the subtyping of BL variants based on their EBV status rather than their geographic origin. Moreover, the pattern of DNAme in EBV+ BL might suggest epigenetic silencing and deregulated ubiquitination as means alternative to gene mutation to be involved in the pathogenesis of EBV+ BL. Keywords: Aggressive B-cell non-Hodgkin lymphoma, Genomics, Epigenomics, and Other -Omics, Pathology and Classification of Lymphomas No conflicts of interests pertinent to the abstract.

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

Barriers to HIV-associated lymphoma diagnosis in Soweto, South Africa: A nurse's perspective.

e18727 Background: Delayed diagnosis of aggressive lymphoma in people living with HIV (PLWH) in South Africa is an emerging public health crisis due in part to PLWH living longer on antiretroviral therapy. The main driver of this delay has been shown to occur during the healthcare-practitioner interval that represents the time from presentation to the healthcare center until a diagnosis is confirmed. We set out to explore the barriers contributing to the prolonged healthcare-practitioner interval during the diagnosis of aggressive B-cell lymphoma in PLWH. We provide a nurse perspective, often the first contact a patient will have within the public healthcare sector in Soweto, South Africa. Methods: We conducted a total of nine qualitative in-depth interviews (IDIs) between May-August 2022 with nurses at four public healthcare clinics in Soweto, South Africa. Eligible participants were purposively sampled provided that they had at least 5 years’ experience working with PLWH. All IDI’s were conducted by an experienced, multi-lingual qualitative researcher in a private room at the respective clinic. A semi-structured interview guide was developed to explore the following topics: provider experience in the healthcare system, experience with taking care of PLWH and experience in distinguishing lymphoma from tuberculosis (TB). The interviews lasted on average 67 minutes and were conducted in the participants preferred local language and/or English. IDIs were audio-recorded, transcribed verbatim, and entered into NVIVO for framework data analysis mapped onto a socio-ecological model exploring barriers at the institutional level. Results: Majority of participants were female (7/9; 78%) with a median age of 39 years. Two nurses held enrolled nurse qualifications (entry level) and 7 nurses held professional qualifications with a median of 10 years’ experience in healthcare. Participants report fundamental barriers that occur at the health system level including limited knowledge about lymphoma by providers; structural limitations at the clinic including staffing shortages and limited resources; poor referral/triage process for lymphoma; and lack of continuity in patient care. In contrast, a clear referral process for TB diagnosis and treatment was noted by the nurses. Nurses perceived that patient level barriers that result in advanced stage cancer presentations include use of alternative and traditional medicine. Conclusions: A clear distinction between referral and triage of suspected TB vs lymphoma diagnoses emerged. Nurses perceive that utilization of traditional medicine by patients results in advanced stage cancer diagnoses. Interviews with lymphoma patients are ongoing and interviews with providers at the TB clinics and with traditional healers in the region are planned to better understand the role that these barriers play in delayed lymphoma diagnosis in South Africa.

Outcomes among adult recipients of CD19 CAR T-cell therapy for Burkitt lymphoma.

7571 Background: Burkitt lymphoma (BL) is a rare, but highly aggressive B-cell lymphoma associated with especially poor outcomes in patients with relapsed/refractory disease. Multiple CD19 chimeric antigen receptor (CAR) T-cell products have been FDA approved to treat relapsed/refractory B-cell non-Hodgkin lymphoma in the second-line setting, however little is known about CAR T-cell responses in patients with BL. This multicenter study aims to assess real-world outcomes among patients with BL treated with CAR T-cell therapy across the United States. Methods: This multicenter, retrospective chart review was conducted by abstracting data from the medical charts of patients with BL who received CAR T-cell therapy. Demographic characteristics were assessed along with pre-CAR treatments, bridging therapies, infusion-related complications, CAR-T responses, and the use of post-CAR systemic therapy and/or hematopoietic stem cell transplant. Results: A total of 13 patients with relapsed/refractory BL received CAR T-cell therapy after a median of 3 prior therapies (range 1-6). Most patients received axi-cel (n = 8), although tisa-cel (n = 3) and liso-cel (n = 2) were also represented. The median age of these patients was 38 (range 24-68). A total of 6 (46.2%) had evidence of central nervous system involvement at diagnosis and 5 (38.5%) had a prior history of autologous stem cell transplant. The overall response rate 1 month after infusion was 69.2% with a complete response rate of 53.8%. All patients experienced grade 1-2 cytokine release syndrome (CRS). No one experienced grade ≥3 CRS, but 2 patients developed grade ≥3 immune effector cell-associated neurotoxicity syndrome (ICANS). Twenty-eight-day mortality was 23%, including one patient who died from grade 4 ICANS. Regarding long term data, only 4 (30.8%) patients sustained a complete response for more than 6 months. Median progression-free survival was 4.2 months (95% CI 28.2-257.6), and the 1-year overall survival rate was 61.5% (95% CI 0.56-0.67). Two (15.4%) patients received consolidative allogeneic stem cell transplants after CAR T-cell therapy, but both ultimately developed progressive disease. Conclusions: Relapsed/refractory BL is a rare and aggressive disease that remains challenging to treat despite the advent of CAR T-cell therapy. Further investigation is needed to determine the most effective management of these patients. We expect to include additional patients in this analysis over the coming months.

Characterization and clinical impact of the tumor microenvironment in post-transplant aggressive B-cell lymphomas.

Post-transplant lymphoproliferative disorders (PTLDs) are iatrogenic immune deficiencyassociated lymphoid/plasmacytic proliferations developing due to immunosuppression in solid organ or hematopoietic stem cell allograft patients. PTLDs are characterized by abnormal proliferation of lymphoid cells and have a heterogeneous clinical behavior. We profiled expression of >700 tumor microenvironment (TME)-related genes in 75 post-transplant aggressive B-cell lymphomas (PT-ABCLs). EBV-positive PT-ABCLs clustered together and were enriched for type I interferon pathway and antiviral response genes. Additionally, a cytotoxicity gene signature associated with EBV-positivity and favorable overall survival (OS; HR 0.61, P=0.019). In silico immunophenotyping revealed two subgroups with distinct immune cell compositions. The inflamed subgroup with higher proportions of immune cells had better outcome compared to non-inflamed subgroup (median OS >200.0 vs. 15.2 months, P=0.006). In multivariable analysis with EBV status, International Prognostic Index, and rituximab-containing treatment, the inflamed TME remained as an independent predictor for favorable outcome. We also compared the TME between posttransplant and immunocompetent host diffuse large B-cell lymphomas (DLBCLs) (n=75) and discovered that the proportions of T cells were lower in PT-DLBCL. In conclusion, we provide a comprehensive phenotypic characterization of PT-ABCLs, highlighting the importance of immune cell composition of TME in determining the clinical behavior and prognosis of PT-ABCL.

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

Introduction: Burkitt lymphoma (BL) is a highly aggressive B-cell lymphoma; because of its fast growing rate, it often represents a clinical emergency. Intensive treatment approaches are required for adult BL, although a univocal standard of care still does not exist. The use of frontline autologous transplantation (ASCT) is debated. Methods: Between 2004 and 2020, 50 HIV-negative BL patients were treated with the Berlin-Frankfurt-Münster (BFM) protocol at our institution. Treatment plan consisted of 3 blocks, A (ifosfamide, vincristine, methotrexate, etoposide, cytarabine), B (vincristine, cyclophosphamide, methotrexate, doxorubicin) and C (vindesine, methotrexate, etoposide, cytarabine), each repeated twice, every 28 days. Patients elder than 60 years did not receive block C, thus blocks A and B were repeated 3 times. Rituximab was given at day 1 each block. Central nervous system (CNS) prophylaxis with intrathecal cytarabine, methotrexate and dexamethasone was given once per each block. Autologous stem cells were harvested after the 4th or 5th cycles, with reinfusion (ASCT) at the end of the 6-blocks after BEAM (carmustine, etoposide, cytarabine, melphalan) conditioning, when feasible. Results: Median age at onset was 38 years (range 16–72); 387 patients were male and 12 female. Stage III-IV disease was observed in 82% of cases; bulky disease occurred in 44% of the patients, with B-symptoms in 38%. Two patients did not receive rituximab because of adverse reaction and early death. Intrathecal prophylaxis was given in 96% of patients. Stem cell harvest was performed in 70% of patients, who all received a subsequent ASCT. The full 6-blocks treatment was completed in 70% of the patients; 8% received 5 cycles and 22% received ≤3 cycles. Early treatment interruption occurred because of disease progression (12%), toxicity (8%), death (4%) or other causes (4%). The overall response rate was 74%, with a complete response rate of 60%. Three patients could not be evaluated because of early progression/death. Ten-year overall survival and progression-free survival were 83.7% and 76.0%, respectively, with both curves exhibiting a plateau. Likewise, 10-year disease-free survival was 80.3%. Eight patients had died because of disease progression (3 patients), infection or sepsis (4 patients) or cardiac arrest (1 patient). Grade 3–4 neutropenia, thrombocytopenia, anemia and mucositis were seen in 96%, 60%, 32% and 24% of patients, respectively. Infections occurred in 60% of patients, with grade 4 and fatal sepsis in 14% and 8% of cases, respectively. Methotrexate-related hepatic and renal toxicity occurred in 16% and 12% of patients, respectively, with complete recovery in all cases. Keywords: Chemotherapy, Immunotherapy, Stem Cell Transplant No conflicts of interests pertinent to the abstract.

Polatuzumab vedotin with infusional chemotherapy for untreated aggressive B-cell non-Hodgkin lymphomas.

The POLARIX trial demonstrated the superiority of polatuzumab vedotin (Pola) over vincristine in the rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone (R-CHOP) regimen for large B-cell lymphomas, but it is unknown whether Pola can be safely incorporated into intensified regimens (eg, dose-adjusted [DA]-EPOCH-R [etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab]) typically used for the highest risk histologies. This was a single-center, open-label, prospective clinical trial of 6 cycles of Pola-DA-EPCH-R (vincristine omitted) in aggressive large B-cell lymphomas. The primary end point was to estimate the safety of Pola-DA-EPCH-R as measured by the rate of dose-limiting toxicities (DLTs) in the first 2 cycles with prespecified suspension rules. Secondary and exploratory end points included efficacy and correlation with circulating tumor DNA (ctDNA) levels. We enrolled 18 patients on study, and with only 3 DLTs observed, the study met its primary end point for safety. There were 5 serious adverse events, including grade 3 febrile neutropenia (3, 17%), grade 3 colonic perforation in the setting of diverticulitis, and grade 5 sepsis/typhlitis. Among 17 evaluable patients, the best overall response rate was 100%, and the complete response rate was 76%. With a median follow-up of 12.9 months, 12-month event-free survival was 72%, and 12-month overall survival was 94%. No patient with undetectable ctDNA at the end of treatment has relapsed to date. Using Pola to replace vincristine in the DA-EPOCH-R regimen met its primary safety end point. These data support the further evaluation and use of this approach in histologies where the potential benefit of both an intensified regimen and Pola may be desired. This trial was registered at www.clinicaltrials.gov as #NCT04231877.

Rituximab/bendamustine/cytarabine for transplant-eligible patients with mantle cell lymphoma: A retrospective study.

Mantle cell lymphoma is considered an aggressive B-cell lymphoma. The optimal induction regimen remains controversial as no randomized controlled trial has compared the efficacy of different induction therapies. Herein, we performed a retrospective analysis of the clinical characteristics of 10 patients who received induction treatment consisting of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) and rituximab, bendamustine, and cytarabine (R-BAC) at Toranomon Hospital between November 2016 and February 2022. Although one patient discontinued R-BAC therapy due to a rash, the other nine completed the scheduled chemotherapy. All patients achieved complete response, underwent high-dose chemotherapy and autologous stem cell transplantation, and maintained complete remission with a median follow-up of 15 months. Hematological adverse events (AEs) occurred in all patients; however, none developed documented infection. There were also no fatal non-hematological AEs specific to R-BAC. R-CHOP/R-BAC may be a good induction therapy for transplant-eligible patients with mantle cell lymphoma.

Double-hit and double-expressor primary central nervous system lymphoma: Experience from North India of an infrequent but aggressive variant.

High-grade non-Hodgkin B-cell lymphoma is an aggressive mature B-cell lymphoma that depicts poor treatment response and worse prognosis. The presence of MYC and B-cell lymphoma 2 (BCL2) and/or B-cell lymphoma 6 (BCL6) rearrangements qualifies for triple-hit and double-hit lymphomas (THL/DHL), respectively. We attempted to explore the incidence, distribution, and clinical characteristics of the primary high-grade B-cell lymphoma of the central nervous system (CNS) in our cohort from North India. All the histologically confirmed cases of primary CNS diffuse large B-cell lymphoma (PCNS-DLBCL) over a period of 8 years were included. Cases showing MYC and BCL2 and/or BCL6 expression on immunohistochemistry (IHC) (double- or triple-expressor) were further analyzed by fluorescence in situ hybridization for MYC, BCL2 and /or BCL6 rearrangements. The results were correlated with other clinical and pathological parameters, and outcome. Of total 117 cases of PCNS-DLBCL, there were seven (5.9%) cases of double/triple-expressor lymphomas (DEL/TEL) (six double- and one triple-expressor) with median age of 51 years (age range: 31-77 years) and slight female predilection. All were located supratentorially and were of non-geminal center B-cell phenotype. Only triple-expressor case (MYC+/BCL2+/BCL6+) demonstrated concurrent rearrangements for MYC and BCL6 genes indicating DHL (n = 1, 0.85%), while none of the double-expressors (n = 6) showed MYC, BCL2, or BCL6 rearrangements. The mean overall survival of the DEL/TEL was 48.2 days. DEL/TEL and DHL are uncommon in CNS; mostly located supratentorially and are associated with poor outcome. MYC, BCL2, and BCL6 IHC can be used as an effective screening strategy for ruling out double/ triple-expressor PCNS-DLBCLs.

Progression of follicular lymphoma and related entities: Report from the 2021 SH/EAHP Workshop.

The 2021 Society for Hematopathology and European Association for Haematopathology Workshop addressed the molecular and cytogenetic underpinnings of transformation and transdifferentiation in lymphoid neoplasms. Session 4, "Transformations of Follicular Lymphoma," and session 5, "Transformations of Other B-Cell Lymphomas," included 45 cases. Gene alteration analysis and expression profiling were performed on cases with submitted formalin-fixed, paraffin embedded tissue. The findings from session 4 suggest that "diffuse large B-cell lymphoma/high-grade B-cell lymphoma with rearrangements of MYC and BCL2" is a distinct category arising from the constraints of a preexisting BCL2 translocation. TdT expression in aggressive B-cell lymphomas is associated with MYC rearrangements, immunophenotypic immaturity, and a dismal prognosis but must be differentiated from lymphoblastic -lymphoma. Cases in session 5 illustrated unusual morphologic and immunophenotypic patterns of transformation. Additionally, the findings support the role of cytogenetic abnormalities-specifically, MYC and NOTCH1 rearrangements-as well as single gene alterations, including TP53, in transformation. Together, these unique cases and their accompanying molecular and cytogenetic data suggest potential mechanisms for and unusual patterns of transformation in B-cell lymphomas and indicate numerous opportunities for further study.

Identification of Potential Therapeutic Targets for Plasmablastic Lymphoma Through Gene Expression Analysis: Insights into RAS and Wnt Signaling Pathways

Plasmablastic lymphoma (PBL) is a rare and aggressive B-cell lymphoma with overlapping characteristics with diffuse large B-cell lymphoma (DLBCL) and multiple myeloma. Hyperactive Wnt signaling derails homeostasis and promotes oncogenesis and chemoresistance in DLBCL and multiple myeloma. Evidence suggests active cross-talk between the Wnt and RAS pathways impacting metastasis in solid cancers in which combined targeted therapies show effective results. Recent genomic studies in PBL demonstrated a high frequency of mutations linked with the RAS signaling pathway. However, the role of RAS and Wnt signaling pathway molecule expression in PBL remained unknown. We examined the expression of Wnt and RAS pathway-related genes in a well-curated cohort of PBL. Because activated B cells are considered immediate precursors of plasmablasts in B cell development, we compared this data with activated B-cell type DLBCL (ABC-DLBCL) patients, employing NanoString transcriptome analysis (770 genes). Hierarchical clustering revealed distinctive differential gene expression between PBL and ABC-DLBCL. Gene set enrichment analysis labeled the RAS signaling pathway as the most enriched (37 genes) in PBL, including upregulating critical genes, such as NRAS, RAF1, SHC1, and SOS1. Wnt pathway genes were also enriched (n = 22) by gene set enrichment analysis. Molecules linked with Wnt signaling activation, such as ligands or targets (FZD3, FZD7, c-MYC, WNT5A, WNT5B, and WNT10B), were elevated in PBL. Our data also showed that, unlike ABC-DLBCL, the deranged Wnt signaling activity in PBL was not linked with hyperactive nuclear factor κB and B-cell receptor signaling. In divergence, Wnt signaling inhibitors (CXXC4, SFRP2, and DKK1) also showed overexpression in PBL. The high expression of RAS signaling molecules reported may indicate linkage with gain–in-function RAS mutations. In addition, high expression of Wnt and RAS signaling molecules may pave pathways to explore benefiting from combined targeted therapies, as reported in solid cancer, to improve prognosis in PBL patients.