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Abstract Family history of hematologic malignancy (FHHM) is an established risk factor for developing lymphoma, but studies examining associations between self-reported FHHM and lymphoma prognosis during the recent treatment era are limited. Utilizing a prospective cohort study, we evaluated associations between FHHM and prognosis for common lymphoma subtypes, including diffuse large B-cell (DLBCL), follicular (FL), marginal zone (MZL), mantle cell (MCL), Hodgkin (HL), and T-cell (TCL) lymphomas. We used the Mayo Clinic component of the Molecular Epidemiology Resource, a prospective cohort study of newly diagnosed lymphoma patients enrolled from 2002 to 2015. Self-reported FHHM (HL, NHL, leukemia, or multiple myeloma) in a first-degree relative was obtained via questionnaire. Primary outcomes were overall survival (OS) and event-free survival (EFS; time from diagnosis to disease progression, initiation of second-line therapy, or all-cause death). Secondary outcomes were failure to achieve 24 months of event-free survival (EFS24; associated with aggressive disease and poor outcomes) and lymphoma-specific survival (LSS; time from diagnosis to death from lymphoma or lymphoma treatment-related complications). We used multivariable Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for the association of FHHM with OS, EFS, and LSS, and logistic regression to estimate odds ratios (ORs) and 95% CI for the association with failure to achieve EFS24. All models were adjusted for sex and a lymphoma subtype specific prognostic index. The cohort consisted of 650 DLBCL, 679 FL, 291 MZL, 178 MCL, 254 HL, and 196 TCL patients. The prevalence of FHHM ranged from 9.7% in TCL to 14% in FL. FHHM was not associated with OS in any subtype, but MCL patients with FHHM showed an inferior EFS (HR=1.70, 95% CI 1.02-2.85; p=0.04). For EFS24, FHHM was associated with failure to achieve EFS24 only in FL (OR=1.57, 95% CI 0.99-2.48; p=0.05). Similarly, FHHM was associated with inferior LSS in FL patients (HR=1.98, 95% CI 1.11-3.53; p=0.02). In a treatment subgroup analysis of FL patients, the FHHM associations with failure to achieve EFS24 (OR=2.48, 95% CI 1.04-5.74; p=0.04) and inferior LSS (HR=2.68, 95% CI 1.09-6.58; p=0.03) strengthened among those treated with frontline immunochemotherapy (IC). In summary, there were no evidence of associations between FHHM and OS across lymphoma subtypes, but MCL patients with FHHM displayed inferior EFS. FL patients with FHHM were more likely to not achieve EFS24 and to ultimately die of their lymphoma or a lymphoma treatment-related complication. This finding was stronger in more aggressive FL requiring frontline IC. This novel finding would suggest that genetic or environmental factors associated with FHHM may underlie pathways that impact disease aggressiveness and early clinical failure in FL. Citation Format: George Cholack, Raphael Mwangi, Thomas M. Habermann, Verena Hinder, Rosalie Griffen, Dennis Robinson, Andrew L. Feldman, Thomas E. Witzig, Stephen M. Ansell, Brian K. Link, Yucai Wang, Carrie A. Thompson, Susan L. Slager, Matthew Maurer, Anne J. Novak, James R. Cerhan. Family history of hematologic malignancy and prognosis across lymphoma subtypes: Novel association with poor outcomes in follicular lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7344.

ABSTRACT As the treatment paradigm for Waldenström macroglobulinemia (WM) continues to evolve, the debate surrounding the prioritization of depth of response versus disease control as therapeutic goals gains significant relevance. However, the impact of depth of response from fixed‐duration therapy on overall survival (OS) was unclear. This multicenter study evaluated the prognostic impact of depth of response using a landmark survival analysis. A total of 440 patients with WM treated with frontline fixed‐duration regimens were included. Attaining a major response (MaR) was associated with superior outcomes, including significantly longer OS. The estimated 5‐year PFS rates for patients with MaR at 6 months versus not were 50% versus 32%, respectively, p < 0.001, and the estimated 5‐year OS rates for patients with MaR at 6 months versus not were 89% versus 70%, respectively, p < 0.001. In a multivariable analysis, MaR at 6 months was independently associated with superior PFS (HR 0.66, p = 0.007) and OS (HR 0.28, p < 0.001). Similar results were seen when considering deeper responses (CR + VGPR vs. PR). Depth of response at 6 months is an important prognostic marker in WM and an independent predictor of PFS and OS. These results support its utilization as a suitable endpoint in clinical studies in WM.

Abstract Background: Diffuse large B-cell lymphoma (DLBCL) is clinically heterogeneous, and gene expression profiling has identified at least two biologically distinct DLBCL subtypes defined by their cell of origin (COO): germinal center B cell (GCB) and activate B cell (ABC) or non-GCB. We evaluated a variety of putative DLBCL risk factors for etiologic heterogeneity by the COO in a clinic-based study of newly diagnosed DLBCL cases (N = 638) and frequency-matched controls (N = 2,253). Methods: The COO was determined on formalin-fixed, paraffin-embedded tumor tissue, with DLBCL classified as GCB (N = 283), non-GCB (N = 188), or undetermined/missing (N = 167; mainly because of lack of tissue). Multivariable logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Results: We identified heterogeneity by the COO for low socioeconomic status (SES), which was only associated with non-GCB DLBCL (OR = 1.88 for low vs. average SES; 95% CI, 1.08–3.27); alcohol use, which was only associated with GCB DLBCL (OR = 0.48 for former drinkers; 95% CI, 0.29–0.80 and OR = 0.47 for current drinkers; 95% CI, 0.32–0.71); and borderline heterogeneity for the regular use of regular/extra-strength aspirin, which was only associated with non-GCB DLBCL (OR = 0.36; 95% CI, 0.16–0.85). In contrast, there was no significant heterogeneity by the COO for family history, medical history, or other lifestyle factors. Conclusions: Although requiring confirmation, most risk factors for DLBCL did not show etiologic heterogeneity by the COO, with some notable exceptions including alcohol use, SES, and perhaps regular use of regular/extra-strength aspirin showing associations. Impact: Mechanistically, these findings suggest that most of the DLBCL risk factors evaluated here influence lymphomagenesis prior to differentiation into COO subtypes, with selected factors acting later.

Abstract Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma involving the brain, cerebrospinal fluid, or retina/vitreous without systemic involvement. Induction with high-dose methotrexate (HD-MTX) followed by consolidation with autologous stem cell transplant (auto-SCT) has become the standard treatment paradigm for most patients. However, limited data are available regarding the efficacy of a maintenance approach with HD-MTX. Herein, we retrospectively reviewed the characteristics and outcomes of 148 patients diagnosed with PCNSL between October 2010 and June 2022, who underwent HD-MTX–based induction therapy followed by either auto-SCT consolidation (n = 70) or HD-MTX maintenance therapy (n = 37). At a median follow-up time of 4.5 years, the progression-free survival (PFS) was 8.3 years and the overall survival (OS) was not reached. Compared to patients who underwent auto-SCT, patients who received maintenance HD-MTX had a higher median age at diagnosis of 72 vs 62 years and a trend toward higher proportion of patients being Eastern Cooperative Oncology Group 2 or higher (41% vs 29%). At 5-years postinduction treatment initiation, the PFS rates in the auto-SCT cohort and HD-MTX maintenance cohort were 74.6% and 72.6%, respectively, and the OS rates were 76.0% and 82.4%, respectively. Overall, there was no significant difference in PFS or OS based on postinduction management strategy. Our data suggest that maintenance HD-MTX may be a reasonable, time-limited treatment strategy for patients with PCNSL responding to initial induction therapy.

ABSTRACT Rituximab, gemcitabine, and oxaliplatin (R‐GemOx) is a commonly used chemoimmunotherapy regimen for relapsed or refractory (R/R) diffuse large B‐cell lymphoma (DLBCL), but there are limited real‐world data. In a multicenter retrospective study from a cohort of eight US academic centers (LEO CReWE), we evaluated 183 patients with R/R DLBCL and high‐grade B cell lymphoma treated with R‐GemOx, including subgroups treated without intent for consolidation with autologous stem cell transplant (ASCT) or chimeric antigen receptor (CAR) T cell therapy ( n = 100), those utilizing R‐GemOx as a bridge to ASCT or CAR T ( n = 83), and those aged 70 and older ( n = 71). Overall response rates (ORRs) for all patients treated with R‐GemOx were 45% with a complete response (CR) rate of 29%. The median event‐free survival (EFS) was 2.3 months, and the median overall survival (OS) was 13.5 months. Patients receiving R‐GemOx without intent for ASCT or CAR T had ORR and CR rates of 33% and 18%, respectively, with median EFS and OS of 2.0 and 9.5 months, respectively. Patients receiving R‐GemOx as a bridge to ASCT or CAR T had ORR and CR rates of 57% and 36%, respectively, with median EFS and OS of 3.5 and 17.4 months, respectively. Patients receiving R‐GemOx aged 70 and older had ORR and CR rates of 53% and 33%, respectively, with median EFS and OS of 2.2 and 13.9 months, respectively. These data provide a benchmark for R‐GemOx in the rapidly evolving landscape of R/R DLBCL therapies.

Background: Positron emission tomography (PET) scan is the imaging modality of choice for initial staging and response assessment of follicular lymphoma (FL). Quantitative parameters such as standardized uptake value (SUV) have been investigated as putative prognosticators in FL, with high baseline SUVmax predicting aggressive disease. To date, there is no data to guide treatment choices in patients (pts) with high SUVmax but with no documented evidence of histologic transformation (HT). Specifically, it remains unclear whether anthracycline-containing regimens, such as R-CHOP, are more beneficial than R-Bendamustine (BR) in these pts. Therefore, we aimed to compare the efficacy of frontline R-CHOP and BR in newly diagnosed FL pts based on the SUVmax at baseline PET (bPET). Patients and Methods: Pts with newly diagnosed, biopsy-proven FL1-2 and FL3A who had a bPET scan and who received either first-line R-CHOP or BR within 6 months of diagnosis between 2002 and 2022 were evaluated. Analysis was restricted to pts with age &lt; 70 years to reduce confounding of age with treatment selection. Cohorts included were the FOLL12 (n=562, Luminari et al JCO 2022) and the R-chemotherapy arm of the RELEVANCE (n=216, Morschhauser et al NEJM 2018) clinical trials, the prospectively enrolled Molecular Epidemiology Resource (MER) and the Lymphoma Epidemiology of Outcomes (LEO) cohorts (n=288) and a retrospective cohort from 13 Australian centers (n=219). Choice of chemotherapy regimen was per treating physician. Maintenance was per protocol (FOLL12/RELEVANCE) or per treating physician (MER/LEO/Australia). Event-free survival (EFS) and overall survival (OS) were defined as time from treatment initiation to progression, relapse, retreatment or death; both were censored at 72 months due to varying follow-up across cohorts. SUVmax was grouped by tertile within each cohort to account for potential differences in SUVmax distributions and patient populations across cohorts. Kaplan Meier curves and multivariable Cox models cohort-stratified and adjusted for clinical factors (FLIPI, ECOG PS, age, grade 3A) were used to evaluate outcomes. Results: The median age at diagnosis was 57 years (IQR 49-64). 651 (51%) pts were treated with R-CHOP and 634 (49%) with BR. Within the study cohorts, there was a prevalence of cases receiving BR compared to R-CHOP in the Australian (90% vs 10%) and MER/LEO (68% vs 32%) cohorts, while the opposite was observed in the RELEVANCE (16% vs 84%) and FOLL12 (37% vs 63; p&lt;0.001) trials. Pts receiving R-CHOP were slightly younger (median 56 vs 58 years, p=0.005), more frequently had grade 3A (17% vs 7%, p&lt;0.001), elevated LDH (27% vs 22%, p=0.029), bulky disease &gt; 7 cm (44% vs 37%, p=0.019), lower ECOG PS (PS &gt;1 7% vs 13%, p&lt;0.001), and higher rate of high risk FLIPI (37% vs 30%, p=0.005). Baseline SUVmax was slightly lower in R-CHOP (median 10.7, IQR 7.9-14.9) vs BR (median 11.0, IQR 8.2-14.2) treated pts (p=0.0045). At a median follow-up of 56 months (range, 1-72 months), 415 pts (32%) had an event and 103 (8%) died. Higher SUVmax was not associated with EFS (middle tertile HR=0.96, 95% CI 0.76-1.22; upper tertile HR=0.86, 95% CI 0.68-1.09; p=0.45) or OS (middle tertile HR=1.28, 95% CI 0.80-2.05; upper tertile HR=0.97, 95% CI 0.59-1.59; p=0.44) in multivariable models stratified on cohort and adjusted for treatment and clinical factors. We then compared outcomes by treatment within tertiles of SUVmax. In multivariable models, R-CHOP had modestly inferior EFS to BR in low (HR=1.27, 95% CI 0.84-1.93) and middle tertiles (HR=1.49, 95% CI 0.99-2.25), and modestly superior OS to BR in low (HR=0.59, 95% CI 0.23-1.47) and middle (HR=0.79, 95% CI 0.37-1.71) tertiles. Both EFS (HR=1.06, 95% CI 0.71-1.58) and OS (HR=1.02, 95% CI 0.45-2.30) for R-CHOP were similar to BR in the highest tertile. No comparisons identified a statistically significant benefit for either therapy in multivariable models when evaluating SUVmax tertile subsets. Conclusions: In this large multicenter study of newly diagnosed FL pts with bPET who received frontline immunochemotherapy, higher baseline SUVmax was not associated with inferior outcomes after adjusting for treatment and clinical factors. Within the caveats of retrospective studies and confounding of treatment selection, these data provide no clear insights for SUVmax-based therapy selection in first-line follicular lymphoma pts treated with immunochemotherapy.

Background: Splenic marginal zone lymphoma (SMZL) is a rare indolent disease with a median overall survival (OS) of more than 10 years, although a proportion of patients may develop aggressive histology transformation. In a previous report from this large, international dataset, the 10-year cumulative incidence of transformation was 17% (95% 13-21) and in another study of 186 patients, the 10-year cumulative incidence was 14%Click or tap here to enter text.. In this report, we focus on risk factors for transformation as well as clinical characteristics and outcomes of transformed SMZL (tSMZL). Patients and methods: Adults diagnosed with SMZL in 2000-2018 were identified through regional or nationwide population-based registries or from hospital registries. Only patients likely to have SMZL as defined by Matutes et al. were included. Those with discordant lymphoma and/or transformation at diagnosis were excluded. Medical records were reviewed by local clinicians with experience in hematology/oncology, and detailed information on clinical characteristics, treatment lines, and outcomes was collected. Only histologically confirmed high-grade transformations (HT) were included. OS was defined as the time from transformation to death or censoring at last follow-up. Additional analyses stratified by treatment exposure prior to HT and treatment of HT were conducted. Multivariable Cox analyses were performed to determine clinicopathological features associated with transformation and OS. Results: Out of 940 patients with SMZL, 111 developed HT during a median follow-up of 9.1 years. The median time from diagnosis to HT was 3.4 years with an interquartile range of 1.6-7.4 years. Median age at HT was 71 years. Patients with HT shared similar baseline characteristics to those without in terms of age at diagnosis (66.4 vs 67.6), f:m ratio (1.5 vs 1.1) and ECOG ³2 (7.2% vs 7.4%). The 5-yr OS from the time of HT was 42% (CI 95%, 32-54). Of the 111 patients with tSMZL, a complete treatment history from SMZL diagnosis until HT was available for 88 included in the following analyses. By the time of HT, 46 had not received any prior systemic therapy (37 only splenectomy, 9 no therapy), 6 patients had received rituximab alone or combined with splenectomy, and 36 patients had received chemotherapy alone or as part of combined modality treatment. In a uni- and multivariable models for HT, we assessed age, treatment at diagnosis, sex, extra-hilar lymphadenopathy, and extranodal involvement. In both the uni- and multivariable model, age &gt;70 (HR 1.9, 95% CI: 1.1-3.4), immediate treatment including splenectomy (HR 2.0, 95% CI: 1.05-3.6), and extra-hilar lymphadenopathy (HR 1.9, 95% CI: 1.1-3.3) were associated with higher HT hazard, while extranodal involvement (HR 0.23, 95% CI: 0.06-0.84) was associated with a lower HT hazard. At the time of first-line treatment, multivariable analysis revealed similar results and with no association between risk of transformation and treatment strategy (i.e splenectomy alone, rituximab monotherapy or chemotherapy with /without rituximab or splenectomy, and other). At the time of HT, patients who had been previously treated with chemotherapy had an inferior 5-year OS of 24% (95%CI: 13-44%) versus 54% (95%CI: 41-71%) for those who had not received chemotherapy prior to HT. In contrast, there was no difference in the survival of patients that transformed less than or more than 24 months from diagnosis with 5-year OS after HT of 35% (95%CI 20-60%) and 45% (95%CI, 33-61%) respectively. In a multivariable Cox regression analyses of age at time of HT, sex, time since last treatment &lt;24 months, chemo-exposure in previous treatment lines and anthracycline-containing therapy (+/-R) at the time of HT, only prior chemo-exposure was borderline associated with poorer OS (HR 1.8, 95%CI: 0.9-3.5). Conclusion: Patients with SMZL face a notable risk of developing tSMZL over time. Patients in need of immediate treatment at first SMZL diagnosis, age &gt;70 and extrahilar lymphadenopathy had a higher risk of tSMZL and outcomes at the time of HT were poor if patients had been exposed to prior chemotherapy after adjustment for age, sex, and time since last treatment.

Introduction: Outcomes from multidisciplinary lymphoma tumor boards in the molecular era are limited, and the effects of transitioning to virtual formats during the COVID-19 pandemic are not well-documented. This study evaluates how the transition of the Mayo Clinic Lymphoma Tumor Board to a virtual format has impacted its effectiveness and operations. The board, part of the International Mayo Clinic Care Network (MCCN), involves case presentations, subspecialist reviews, and collaborative recommendations. Methods: The Mayo Clinic Lymphoma Tumor Board, an integral part of the Mayo Clinic Care Network (MCCN), conducted a comprehensive review of lymphoma cases from 2014 to 2024. The board's review process involves a structured approach including the presentation of clinical case details, radiology and hematopathology findings, proposed treatment options, relevant literature review, and discussions. From 2014 to 2024, the Mayo Clinic Lymphoma Tumor Board reviewed a total of 722 patients. The review process involves a multidisciplinary team, including physicians, pharmacists, clinical research associates, and trainees. Recommendations and changes related to radiology interpretation, pathologic diagnosis, and treatment approaches were documented and tracked prospectively. In March 2020, the board transitioned to a virtual format due to the COVID-19 pandemic. This shift allowed for remote participation and continued collaborative review while maintaining the board's structured approach and documentation practices. Results: In a total of 722 patients, changes in care were identified in 423 patients, including 287 with newly diagnosed lymphoma and 136 with relapse or refractory disease. Among those who experienced changes, 94 had diffuse large B-cell lymphoma, 49 had follicular lymphoma, 39 had marginal zone lymphoma, 36 had classical Hodgkin lymphoma, and 29 had mantle cell lymphoma. Prior to the COVID-19 pandemic, 431 patients were analyzed, with 217 (50.3%) experiencing changes. A total of 268 changes were documented among these patients. Changes in radiologic interpretation occurred in 9 patients (2.1% of 431 total patients). Pathologic diagnosis changes were noted in 42 patients (9.7%). Additional testing was recommended for 73 patients (16.9%), and clinical management was altered for 144 patients (33.4%). After transitioning to a virtual format, 291 patients were reviewed post-COVID, with 206 (70.8%) having recommended changes. The total number of change recommendations was 322, reflecting increases across all components compared to previous data, with adjustments for varying numbers of patients reviewed. Specifically, radiologic interpretation changes occurred in 21 patients (7.2%), pathologic diagnosis changes in 57 patients (19.6%), additional testing recommendations for 85 patients (29.2%), and clinical management alterations in 159 patients (54.7%). Conclusion: Transitioning to a virtual format in the Mayo Clinic Lymphoma Tumor Board's continued to demonstrate the effectiveness, with increased changes in diagnostic interpretations and clinical management. These results illustrate the potential of virtual tumor boards to improve collaborative decision-making and adapt to evolving clinical needs.

Background: Rituximab, gemcitabine, and oxaliplatin (R-GemOx) is a commonly utilized chemoimmunotherapy regimen for relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL), especially for patients ineligible for autologous stem cell transplant (ASCT) or chimeric antigen receptor T cell therapy (CAR T). R-GemOx is used as a comparator arm in several active phase III clinical trials for R/R DLBCL, including the POLARGO (polatuzumab vedotion and R-GemOx), STARGLO (glofitamab and GemOx), SUNMO (mosunetuzumab and polatuzumab vedotin), LOTIS-5 (loncastuximab tesirine and rituximab), and EPCORE DLBCL-1 (epcoritamab) studies. However, real-world data are limited to understand the patterns of use and outcomes of R-GemOx in the US. Methods: We developed a retrospective multicenter US cohort (known as LEO CReWE) of patients with R/R DLBCL and other aggressive B-cell lymphomas at the eight US academic centers participating in the LEO Cohort Study (NCT02736357). Patients first diagnosed with DLBCL (including transformed and high-grade B-cell lymphoma) from 2007 - 2022 who received second line (2L) or later therapy for R/R DLBCL with R-GemOx were included. Baseline characteristics, treatment, and follow-up data were abstracted by chart review. Index line of therapy was defined as the first receipt of R-GemOx therapy in the 2L or later setting. Intent for CAR T and/or ASCT was evaluated at each line of therapy based on medical records at the time of treatment initiation. Subgroup analyses were pre-planned in groups of special interest, including those treated with R-GemOx without intent for ASCT or CAR T, those treated as a bridge to CAR T, and those aged 70 and older. Results: 183 patients with R/R DLBCL treated with R-GemOx were included. At time of initiation of R-GemOx, median age was 68 years (range 21-88), with 71 patients (39%) aged 70+ and 18 (10%) aged 80+. Many patients had high risk features including 13% with high grade B-cell lymphoma and 56% with IPI 3 or greater. 21% had an ECOG performance status of 2 or greater. Patients received a median of 2 lines of therapy prior to the index line of R-GemOx (range 1-7). 52% of patients did not achieve a complete response (CR) to first-line therapy, and 20% relapsed &lt;12 months from an initial CR. In all patients receiving R-GemOx, the overall response rate (ORR) was 45% (29% CR). At a median follow-up of 39 months, median EFS was 2.3 months (95% CI: 1.8-3.2), with 12-month EFS of 21% and a 24-month EFS of 15%. Median OS was 13.5 months (95% CI: 9.6-18.1), with a 12-month OS of 52% and a 24-month OS of 38%. In patients treated without intent for ASCT or CAR T, ORR was 33% (18% CR). Median EFS was 2.0 months (95% CI: 1.6-2.5) with 12- and 24-month EFS of 14% and 9%, respectively. Median OS was 9.5 months (95% CI: 6.6-16.1) with 12- and 24-month OS of 45% and 29%, respectively. In patients receiving R-GemOx as bridging to ASCT or CAR T, ORR was 57% (35% CR). 35% received CAR T and 14% received ASCT, while the remainder did not receive the intended therapy as part of this line. Median EFS was 3.6 months (95% CI: 1.8-5.2) with 12- and 24-month EFS of 28% and 25%, respectively. Median OS was 17.4 months (95% CI: 13.4-NR); 12- and 24-month OS were 61% and 50%, respectively. In patients aged 70+, ORR was 53% (33% CR). Median EFS was 2.3 months (95% CI: 1.6-5.2), with 12- and 24-month EFS of 20% and 18%, respectively. Median OS was 13.9 months (95% CI: 8.6-30.2); 12- and 24-month OS were 57% and 39%, respectively. Conclusion: This study represents the largest reported cohort of patients treated with R-GemOx in US academic centers to date. The ORR of 45% and CR rate of 29% CR, as well as median EFS and OS of 2.3 and 13.5 months, respectively, are consistent with findings from previous phase II studies; these results highlight that responses to R-GemOx are not durable and the vast majority of patients require additional therapy. This study demonstrates real-world evidence of the efficacy of R-GemOx in a large cohort of patients with R/R DLBCL from the US over a long period, including both transplant-eligible and -ineligible patients, and patients treated in the CAR T era. These data aid in providing a benchmark for active clinical trials in the rapidly evolving landscape of R/R DLBCL therapies and allow potential comparison to a real-world cohort of patients with a broad range of clinical characteristics.

Introduction: Hyaline-vascular type unicentric Castleman disease (HV-UCD) is a classic variant of Castleman disease, characterized by localized lymph node hyperplasia. Due to its rarity, there have been few systematic reports summarizing its clinicopathological features globally. Also, its pathogenesis remains unelucidated. The present study aims to provide a detailed clinicopathological and transcriptomic analysis of HV-UCD to enhance the understanding of its underlying mechanisms at a molecular level. Methods: We conducted a clinicopathological analysis of 51 HV-UCD cases and performed whole transcriptome analysis on frozen lymph node specimens from four cases. Differentially expressed genes (DEGs) and Gene Ontology (GO) analyses were performed to identify significant pathways and biological processes involved in HV-UCD, with reactive lymphoid hyperplasia as control. Results: The mean age of HV-UCD patients was 42.8 years, with no significant gender differences. The most common sites involved were the abdominal cavity (n = 18, 35.3%), mediastinum (n = 11, 21.6%), and retroperitoneum (n = 9, 17.6%), with an average size of the lesions being 4.8 cm. Histologically, 33.3% of cases exhibited “dysplastic follicular dendritic cells (dFDCs)” characterized by multinucleation or large nuclei within and outside follicles, positive for follicular dendritic cells (FDC) markers. DEGs analysis compared to reactive lymphoid hyperplasia revealed significant upregulation of genes related to FDCs and angiogenesis. Notably, the placental growth factor (PGF), a proangiogenic factor and a member of the VEGF family, demonstrated significant overexpression. GO analysis identified significant enrichment of genes involved in angiogenesis, cell adhesion, tissue architecture, and humoral immunity. Discussion: This large cohort of HV-UCD cohort provides potentially novel clinicopathological insights. Gene expression analysis demonstrated increased expression of FDC-related genes, suggesting a pivotal role of FDCs in HV-UCD pathogenesis. The differences in the gene profiles related to angiogenesis may contribute to the distinct mechanisms and histological features of HV-UCD and iMCD-TAFRO, where HV-UCD is associated with hyalinization of vascular walls and iMCD-TAFRO is characterized by angiogenesis with endothelial cell swelling. Conclusion: The present results suggest the crucial role of FDCs in HV-UCD pathogenesis from the molecular features. Currently, there are no objective diagnostic markers for HV-UCD. Identifying these markers may lead to a clearer understanding of the disease pathophysiology and improve diagnostic accuracy for HV-UCD. Further investigation is warranted to verify the findings.