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Background Primary mediastinal large B-cell lymphoma (PMBCL) is an uncommon type of non-Hodgkin lymphoma. Clinicopathologic features are distinct from diffuse large B cell lymphoma, but it shares some clinical and biologic features with Nodular sclerosis classic Hodgkin lymphoma. Central nervous system (CNS) relapse appears to be rare in patients with PMBCL, with limited literature reporting a rate of approximately 1.5% to 4%. We examined the incidence of CNS relapse, treatment approaches and survival outcomes in patients with PMBCL. Methods Patients with newly diagnosed PMBCL seen at Mayo Clinic between 2002 and 2022 were identified using the prospective Mayo Clinic Lymphoma Database. Clinical features, treatment details and outcomes were abstracted from the medical record. Cumulative incidence of CNS relapse was analyzed with death as a competing risk. The association of CNS-IPI, systemic treatment, and CNS prophylaxis approach with CNS relapse rate was analyzed using competing risk models and descriptively. Event-free survival (EFS) for the cohort was defined as time from PMBCL diagnosis to first recorded CNS and/or systemic relapse or death from any cause. Overall survival (OS) was defined as time from PMBCL diagnosis (or CNS relapse) to death from any cause. Survival analysis was performed using the Kaplan-Meier method. Results A total of 124 PMBCL cases were identified. The median age at diagnosis was 37 years and 61% were female. The distribution of CNS-IPI was low-risk in 67 (61%), intermediate-risk in 41 (37%), and high-risk in 2 (2%). 64 patients (52%) received R-CHOP and 54 patients (44%) received R-DA-EPOCH as frontline therapy. High-dose methotrexate (HD-MTX) for CNS prophylaxis was administered to 6 patients (5%), 5 with R-CHOP and 1 with R-DA-EPOCH. 16 patients received intrathecal (IT) chemotherapy (methotrexate and/or cytarabine) for CNS prophylaxis, 3 with R-CHOP and 13 with R-DA-EPOCH. The median follow-up was 56.0 months. The 5-year EFS rate was 75.1% and the 5-year OS rate was 90.7% for the entire cohort. 20 patients had systemic relapse only and 3 had CNS relapse. The cumulative incidence of CNS relapse was 1.84% (95% CI 0.46%-7.17%) at 2 years and 2.92% (95% CI 0.50%-8.84%) at 5 years (Figure 1). No statistically significant association of CNS-IPI, systemic therapy or CNS prophylaxis regimen with CNS relapse rate was found in competing risk models; however, this analysis was limited by a small event number (n=3). Among the 3 patients with CNS relapse, 1 had high-risk CNS-IPI and 2 had intermediate risk. All 3 patients were treated initially with R-CHOP. Two patients did not receive any CNS prophylaxis and 1 patient received IT CNS prophylaxis. All three patients who had CNS relapse were female. Patient #1 was diagnosed at age 48 and had simultaneous CNS and systemic relapse 6 months later. The patient was treated with HD-MTX, temozolomide and rituximab for CNS relapse, and subsequently received multiple therapies for systemic disease including R-DHAP, R-ICE, and died 17 months after CNS relapse. Patient #2 was diagnosed at age 22 and had CNS relapse after 8.7 months, followed by systemic relapse 2 months later. The patient received HD-MTX, temozolomide and rituximab for CNS relapse, followed by systemic and whole-brain radiation therapy (RT) for both systemic and CNS relapse. Subsequently the patient received salvage chemotherapy, autologous and allogeneic stem cell transplant for systemic relapse. The patient died 26.8 months after CNS relapse. Patient #3 was diagnosed at age 24 and had systemic relapse after 20.7 months, followed by CNS relapse 5.4 months later. The patient received methotrexate and whole-brain RT following CNS relapse and died 1.2 months after CNS relapse. Besides these 3 patients, we identified 6 PMBCL patients with CNS relapse who were diagnosed at other medical centers and subsequently referred to our institution for management of refractory disease. The survival after CNS relapse was poor, with a median OS of 10.4 months (95% CI 5.6-15.2). Conclusion Our study showed that the CNS relapse rate (1.84% at 2 years and 2.92% at 5 years) was overall low in patients with PMBCL, consistent with previous reports. CNS relapse was associated with poor survival despite aggressive treatment approaches. Novel approaches utilizing biological risk factors for CNS relapse, such as circulating tumor DNA, are needed to identify patients with CNS relapse.

Despite notable advancements in treating chronic lymphocytic leukemia (CLL) with targeted therapies, a significant clinical challenge arises as a subset of CLL patients progress and develop Richter's transformation (RT), an aggressive form of lymphoma. While immune cell dysfunction and T cell defects are well-known characteristics of CLL, the alterations in immune cell subsets during CLL progression to RT remain largely unexplored. While CLL patients typically fail to respond to anti-PD1 pembrolizumab, a positive response has been observed in 20-40% of RT patients. Previously, our study involving three RT patients (1 responder and 2 progressors) revealed enriched regulatory T cells (Tregs) in the responders compared to progressors after pembrolizumab treatment (Iyer et al, ASH2020). Hence, we propose that dynamic changes in T cell subsets at baseline may be associated with response to pembrolizumab treatment. To this end, we performed single-cell RNA sequencing on sorted T cells (CD3 +) from PBMCs derived from 20 patients (responders (RES), n=5; stable disease (SD), n=5; progressive disease/progressors (PD), n=10). A total of 408,627 cells were captured, and an average of 1,393 genes were detected per cell per patient. Using a graph-based clustering approach (Seurat V4.3), we identified 19 clusters based on marker genes and transcriptional signatures and identified enriched pathways using Enrichr analysis. Our results showed that RES had an increased Th17 subset at baseline compared to PD (15% vs. 5%, p=0.01) and reduced Th2 T cells compared to SD (p=0.004) and PD (p=0.05). The Th17/Th2 ratio was higher in RES at baseline (Th17/Th2 R: 1.24, PD: 0.21, SD: 0.25, p0.05) and post-pembrolizumab (Th17/Th2 RES: 1.31, PD: 0.34, SD: 0.30, p0.05). Furthermore, RES had an increased fraction of proliferating CD4 T cells at baseline (4% RES vs. 0.4% SD and 0.4% PD, p=0.02) and post-treatment (1.9% RES vs. 0.8% PD and 0.34% SD, p=0.02). Although we observed an increasing trend in the fraction of Tregs in the RES at baseline [(7.6% RES vs.6.1% PD and 6.5% SD, p=0.4; ns) and post-treatment (10.3% RES vs. 8.3% PD and 5.8% SD, p= 0.2; ns] compared to PD and SD, the difference was not significant. Similarly, among CD8+ T cells, we observed an increasing trend in CD8+ effector T cell fraction in the responders at baseline (29.8% RES vs. 21% PD and 15.6% SD, p=0.9, ns) and post-treatment (30.1% RES vs. 21.2% PD and 19.9% SD, p=0.44, ns). However, the difference was not statistically significant. These findings highlight the dynamic changes in T cell subsets associated with pembrolizumab response. In terms of transcriptional changes in Tregs following pembrolizumab treatment among RES, PD, and SD, we observed dynamic changes on a few Treg marker genes, including TIGIT and TOX. TIGIT and TOX expression drastically decreased after treatment in RES (p < 0.0001), while expression did not change in PD and SD. There were no significant changes in the expression of FOXP3 or CD27 in RES, PD, and SD before and after the treatment. In CD8 effector T cells, GZMK, GZMA (granzymes), and PRF1 (perforin) are marker genes. We observed higher expression of GZMK and GZMA in RES (p <0.0001) at the baseline compared to SD and PD. In the proliferating CD4 T cells, we observed increased expression of IDH2 (Isocitrate dehydrogenase 2-key enzyme of TCA cycle) in RES at the baseline, as compared to PD and SD, indicating increased TCA cycle activity in the proliferating T cells. Pathway analysis of T cell clusters using the Enrichr database showed TNFA-IFNG-MYC targets are enriched in CD8 + cells, IL2-STAT5 signaling is upregulated in Th17, TREGs, and E2F cell cycle associated pathways enriched in CD4 + proliferation cluster. In conclusion, our study unveils significant baseline differences in CD4 subsets between RES and PD/SD subjects and dynamic changes in T cell subsets and transcriptional signatures. These findings offer potential predictors of pembrolizumab response in RT, such as increased Th17/Th2 ratio, enriched proliferating CD4 + T cells, and elevated TIGIT, TOX gene expression in Tregs, GZMK, and GZMA in CD8 effector cells. This deeper understanding of the immunological landscape in RT patients sheds light on the interplay between T cell subsets and treatment response in RT, paving the way for personalized therapeutic strategies. Further validation and exploration can lead to improved outcomes and tailored interventions for RT.

Background: Although marginal zone lymphoma (MZL) typically exhibits an indolent course, transformation to diffuse large B-cell lymphomas (DLBCL) is associated with a poorer outcome and remains a clinical challenge in managing patients with MZL. The limited existing literature reports various cumulative incidence rates, ranging from 2.5% and 4.7% (Finnish Cancer Registry, 1995-2018) to 6.6% and 8.4% (Florida Cancer Registry, 1995-2016) at 5 and 10-years, respectively, likely in part driven by varying study designs, ascertainment, and study population. Similarly, reported outcomes after transformed MZL (tMZL) have been variable. We evaluated the cumulative incidence of histological transformation (HT) to LBCL in a well-characterized prospective cohort of MZL patients from the upper Midwest, USA, and overall survival (OS) after transformation. Methods: Patients ≥ 18 years old with newly diagnosed MZL were prospectively enrolled in the University of Iowa/Mayo Clinic Molecular Epidemiology Resource (MER) cohort from 2002-2015. Clinical and treatment data were abstracted from medical records using a standard protocol. Patients were actively followed for retreatment, transformation, and death through 2022. Pathology was classified according to WHO 4/4R, including all transformations. The cumulative incidence of HT to LBCL was determined using death as a competing risk. Time to HT (TTHT) was defined as time from the date of MZL diagnosis to the date of transformation. We evaluated potential predictors of HT using a stepwise approach, and derived hazard ratios (HR) and 95% confidence intervals (CI) from Cox proportional hazards models. To assess predictors of OS after HT, patients ≥ 18 years old with newly diagnosed tMZL (into DLBCL) at Mayo Clinic between 1995 and 2002 (N=7) were combined with the MER cases. Results: We identified 524 patients with MZL in the MER cohort: 362 extranodal (EMZL; lung 18%, stomach 16%, orbit 13%, parotid 10%, skin 10%), 84 splenic (SMZL), and 78 nodal (NMZL). The median age at diagnosis was 63 years (range 18-92); 56% were female, and 83% were non-Hispanic white. During a median follow-up of 18.8 years (95% CI 16.7, NA), there were 25 HT (including 8 patients under observation) and 158 deaths. Eight Ten-year OS was 67% and 77% in the groups with and without HT, respectively. The overall cumulative incidence of HT was 1.5% at 2 years after diagnosis, 2.9% at 5 years, 4.5% at 10 years, and 5.7% at 15 years (Panel 1). The cumulative incidence of HT varied by subtype (e.g., at 5 years: 2%, 4% and 6%, in EMZL, NMZL and SMZL, respectively; Panel 2). The median time to HT also varied by subtype: 76 months (interquartile range (IQR) 43, 81) for EMZL, 30 months (IQR 16, 52) for SMZL, and 18 months (IQR 14, 23) for NMZL. In univariable analysis, predictors of HT were Stage III/IV (HR=3.4, 95% CI 1.36-8.53, p=0.009), elevated LDH (HR=2.98, 95% CI 1.25-7.12, p=0.014), and presence of ≥2 extranodal sites (HR=2.69, 95% CI 1.22-5.94, p=0.014). In multivariable analysis, elevated LDH was the only non-composite predictor of HT (HR=2.65, 95% CI 1.08-6.52, p=0.034). MALT-IPI score 2-3 (HR=3.61, 95% CI 1.06-12.25, p=0.040) and FLIPI score 3-5 (HR=2.19, 95% CI 1.22-8.22, p=0.018) also predicted HT. We analyzed OS after HT in 32 cases of tMZL (21 tEMZL, 7 tSMZL, 4 tNMZL). At HT, median age was 68 years (range 39-89); 24 (80%) patients presented with stage III/IV disease, 11 (58%) with elevated LDH, 12 (55%) with hemoglobin <12g/dL, 3 (14%) with platelet count <100x10 9/L and 9 (39%) with biopsy-proven bone marrow involvement. Twenty-six (81%) were treated with a systemic therapy, mainly CHOP-backbone therapy (R-CHOP n=13, CHOP n=4, R-EPOCH n=3, lenalidomide-R-CHOP n=1). Among these patients, the overall response rate was 85% (n=22/26). Three of the 4 non-responders died within 1 year. At last follow-up, 18/32 (56%) patients had died, and 6/13 (46%) alive patients had relapsed (MZL 3/6, DLBCL 3/6). After HT, 2-, 4- and 10-year OS were 76%, 55% and 55%, respectively. In univariable analysis, the only predictor of OS at HT was age ≥70 (HR 3.57 ,95% CI 1.34-9.48, p=0.011). Conclusion: In this North American prospective cohort of mainly non-Hispanic White patients, we found a low cumulative incidence of HT in MZL of 2.9% and 4.5% at 5- and 10-year, which was consistent with the Finnish findings (Kalashnikov et al., 2023). At HT, age was associated with OS and there was a high response rate to CHOP-backbone therapies.

INTRODUCTION Richter transformation (RT) is the histologic transformation of CLL/SLL into an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL). We previously reported an incidence of 0.5% per year of RT in patients with newly diagnosed CLL and an incidence of 1% per year following initiation of therapy (Parikh, BJH, 2013). It is unknown whether these incidences have changed in the novel agent era. METHODS We identified patients with previously untreated CLL/SLL in the Mayo Clinic CLL Database who were seen within 12 months of diagnosis. Only patients with biopsy-proven DLBCL with histopathology confirmation at Mayo Clinic were included. Cumulative incidence methodology was used to display the time to development of RT with death as a competing risk (both from time of initial CLL/SLL diagnosis, and from start of CLL directed therapy). We defined the time period prior to February 2014 (FDA approval of ibrutinib for CLL) as the pre-novel agent era and the time period starting February 2014 as the novel agent era. Using Cox regression analysis, we compared the incidence of RT, both after initial CLL diagnosis and after initiation of CLL therapy, between patients diagnosed with CLL in the pre-novel agent era versus the novel agent era. RESULTS Between 1/2000 and 4/2023, 3347 patients were seen at Mayo Clinic. The median age at diagnosis was 65 years (range 21-97 years), and 66% patients were male. Baseline characteristics of patients at the time of CLL and RT diagnoses between the two treatment eras were similar, including distance in miles of primary residence from Mayo Clinic ( Table 1). The median follow-up for the entire cohort was 5.6 years (9.5 years for the pre-novel agent era cohort and 3.2 years for the novel agent era cohort). A total of 82 patients were diagnosed with RT (69 in the pre-novel agent era and 13 in the novel agent era). Overall, the 1-, 5- and 10-year cumulative incidence rates for RT from the time of CLL/SLL diagnosis were 0.6% (95% CI: 0.4-0.9%), 1.8% (95% CI: 1.3-2.3%), and 3.0% (95% CI: 2.4-3.8%), respectively. Among the patients who received CLL/SLL therapy (n=1382), the 1-, 5-, and 10-year incidence rates for RT from the time of treatment start were 0.3% (95% CI: 0.1-0.8%), 3.3% (95% CI: 2.4-4.5%), and 4.9% (95% CI: 3.7-6.5%), respectively. Among 1981 patients diagnosed with CLL/SLL in the pre-novel agent era, the 1- and 5-year incidence rates for RT from the time of diagnosis were 0.6% (95% CI: 0.4-1.1%) and 2.1% (95% CI: 1.5-2.8%), respectively. Among 1366 patients diagnosed with CLL/SLL in the novel agent era, the 1- and 5-year incidence rates following CLL/SLL diagnosis were 0.5% (95% CI: 0.2-1.1%) and 1.1% (95% CI: 0.6-2.2%), respectively. The RT incidence from time of CLL/SLL diagnosis was not significantly different between the pre-novel agent and novel agent era patients (hazard ratio [HR] 1.6, 95%CI 0.9-3.0, p=0.13). Patients who received CLL/SLL treatment in the pre-novel agent era (n=926) and novel agent era (n=456) had subsequent 1-year incidence rates of RT of 0.3% (95% CI: 0.1-1.0%) and 0.2% (95% CI: 0.0-1.8%), respectively. The 5-year incidence rates for these groups were 3.7% (95% CI: 2.6-5.2%) and 1.9% (95% CI: 0.7-5.0%), respectively. Although an increased risk of RT after CLL/SLL directed therapy was observed in the pre-novel agent era compared to the novel agent era (HR 2.4, 95%CI: 0.9-6.1, p=0.07; Figure 1), this did not cross the threshold of statistial significance. Among patients diagnosed in the pre-novel agent era who developed RT (n=69), CLL treatment prior to RT included: none, n=19 (28%); chemoimmunotherapy only, n=36 (52%); and novel agent, n=14 (20%; includes 11 treated with prior chemoimmunotherapy also). In contrast, among patients diagnosed in the novel agent era who developed RT (n=13), CLL treatment prior to RT included: none, n=8 (62%); and novel agent, n=5 (38%). CONCLUSIONS Patients who received CLL/SLL directed treatment appear to have a lower risk of RT in the novel agent era. This may be driven by the fact that none of the patients who developed RT in the novel agent era received chemoimmunotherapy. Whether novel agent use for CLL/SLL suppresses the development of RT or avoids the risk associated with cytotoxic chemotherapy-induced clonal evolution requires further study. Although limited by length of follow-up, our findings challenge the notion that RT incidence will increase in parallel with CLL patients living longer with novel agent treatments.

Background: Hematological toxicity is a frequent side effect of CAR-T therapy and predisposes for severe infectious complications. Recently, the EHA/EBMT consensus grading for Immune Effector Cell Associated HematoToxicity (ICAHT) was developed ( Rejeski et al. Blood 2023). In contrast to existing grading systems such as the CTCAE, the novel ICAHT grading integrates both the depth and duration of neutropenia. We hypothesized that ICAHT severity is associated with key clinical sequelae such as transfusion requirements, hospitalization, severe infections, and adverse treatment outcomes. Methods: We applied the novel grading of early ICAHT (day 0-30) to a multicenter retrospective real-world cohort of 549 patients treated with BCMA- or CD19-directed CAR T-cells for relapsed/refractory B-cell malignancies (334 large B-cell lymphoma [LBCL], 112 multiple myeloma [MM], 103 mantle cell lymphoma [MCL]) across twelve international sites (Germany, France, Spain, USA). Hematotoxicity endpoints included the total cumulative duration of severe neutropenia (ANC <500/µL, day 0-60) and phenotypes of neutrophil recovery ( Rejeski et al. Blood 2021). Infections were studied until day +90 after CAR-T and were graded on a 5-grade scale as mild, moderate, severe, life-threatening, or fatal. Non-relapse mortality (NRM) was defined as death following CAR-T without evidence of relapse or progression. Kaplan-Meier estimates of progression-free (PFS) and overall survival (OS) were compared using log-rank test. Results: Our study cohort included 424 patients without severe ICAHT (absent or grade 1-2) and 125 patients with severe ICAHT (grade 3-4). The distribution of mild (1°), moderate (2°), severe (3°) and life-threatening (4°) ICAHT was 36%, 29%, 17%, and 5%. Seventy patients (13%) did not develop ICAHT of any grade. When comparing ICAHT grades across disease entities, we noted a numeric trend towards increased severe ICAHT in MCL compared to LBCL or MM patients (Grade ≥3: 28% vs. 23% vs. 15%). Patients that subsequently developed severe ICAHT displayed elevated serum inflammatory markers and pronounced cytopenia at baseline - reflected by increased CAR-HEMATOTOX scores (median 3 vs. 1, p<0.0001). On multivariate binary logistic regression, co-stimulatory domain (CD28z), low platelet count, low ANC, low hemoglobin, increased serum ferritin, and the presence of bone marrow infiltration were independent risk factors for severe ICAHT. We noted a strong positive correlation between ICAHT severity and the cumulative duration of severe neutropenia (r=0.92, p<0.0001). The aplastic phenotype of neutrophil recovery was enriched in patients with grade 3 (73%) and especially grade 4 ICAHT (100%). Severe ICAHT was also associated with coincident multilineage cytopenias, resulting in increased transfusion requirements for both platelets (85% vs. 21%, p<0.0001) and red blood cells (86% vs. 41%, p<0.0001). In terms of management of hematotoxicity, the severe ICAHT group more commonly received G-CSF (72% vs. 44%, p=0.01), TPO mimetics (12% vs. 2%, p<0.0001) and hematopoietic stem cell boosts (6% vs. 0.2%, p<0.0001). Importantly, patients with severe ICAHT displayed a significantly increased rate of severe infections (49% vs. 13%, p<0.0001, Fig. 1a) and severe bacterial infections (36% vs. 8%, p<0.0001). This translated into a markedly increased 1-year NRM rate (14% vs. 4.5%, logrank p<0.0001, Fig. 1b), which was primarily attributed to fatal infections of fungal or bacterial origin. Of note, the ICAHT grading showed superior discrimination for severe infections (C-index 0.73, 95%CI: 0.67-0.78) compared to CTCAE grading (C-index 0.55, n.s.). Prolonged hospitalization was noted in case of severe ICAHT (median 21 vs. 16 days, p<0.0001) and intensive care admission was more common (23% vs. 4%, p<0.001). Finally, we observed inferior PFS (1-year PFS 35% vs. 51%, median 4 vs. 14 months, p<0.0001) and inferior OS (1-year OS 52% vs. 73%, median 12 months vs. not-reached, p<0.0001) in the patients that developed severe ICAHT. Conclusions: These data highlight the clinical relevance of the novel EHA/EBMT ICAHT grading system. Importantly, ICAHT severity was closely associated with transfusion dependence, increased infection incidence, and adverse treatment outcomes with high NRM. Taken together, these findings argue for reporting ICAHT grades in clinical trials evaluating established and novel CAR constructs.

Background:Richter transformation (RT) occurs in up to 10% of patients with chronic lymphocytic leukemia (CLL), typically presents as an aggressive diffuse large B-cell lymphoma (DLBCL) and is associated with poor survival. RT has no approved standard therapy; and clinical trial enrollment is the preferred first line of therapy. Pirtobrutinib, a highly selective, non-covalent (reversible) BTKi, that inhibits both wildtype and C481-mutant BTK with equal low nM potency, has favorable oral pharmacology that enables continuous BTK inhibition throughout the dosing interval. Pirtobrutinib demonstrated durable overall response rates (ORR) and was well tolerated in patients (pts) with poor-prognosis B-cell malignancies regardless of prior therapy. Here we provide updated safety and efficacy of pirtobrutinib in RT pts from the phase 1/2 BRUIN trial (NCT03740529). Methods: Pts with previously treated, histologically confirmed RT were eligible in the global, multicenter, phase 1/2 BRUIN study. Pts with untreated RT became eligible after Amendment 10. All but one patient received the recommended phase 2 dose of 200 mg daily. Key endpoints included investigator-assessed ORR, DoR per Lugano 2014 criteria, OS, and safety. A data cut of 05 May 2023 was utilized. To assess clonal relationship, IGH rearrangement studies were done on tissue biopsies with RT involvement, and baseline blood or bone marrow (BM) samples with CLL involvement. Results: Among all pts with RT (N=82) the median age was 67 (range, 26-95) and the median total number of lines of prior systemic therapy was 4 (range, 0-13). Pts with prior treatment had a median of 2 CLL-directed therapies and 2 RT-directed therapies. Eight pts did not have a previous line of RT-directed therapy, and 1 patient received neither RT- nor CLL-directed therapy. Common prior RT- and CLL-directed therapies (RT, CLL) included: chemotherapy (76%, 52%), cBTKi (34%, 62%), anti-CD20 antibody (78%, 66%), BCL2i (38%, 49%), stem cell transplant (SCT; 6%, 7%), and CAR-T (11%, 4%). Of 29 pts with bone marrow screening, 41.4% had CLL alone present in BM, 13.8% had DLBCL present and 24.1% had both CLL and DLBCL present. For 39 pts with available PET data, the median SUVmax was 19.1 (range, 2.6-41.2). For all 82 pts, the ORR was 50.0% (95% CI, 38.7-61.3) including complete (13.4%, n=11) and partial (36.6%, n=30) responses. For 61 pts who received prior cBTKi therapy, the ORR was 45.9% (95% CI 33.1-59.2). Among 28 pts with an RT-directed cBTKi and 51 pts with prior CLL-directed cBTKi, the ORR was 42.9% (95% CI, 24.5-62.8) and 43.1% (95% CI, 29.3-57.8), respectively. In 50 pts who discontinued prior cBTKi due to disease progression, the ORR was 42.0% (95% CI, 28.2-56.8). At median follow-up time of 9.7 months, the median DoR for all 82 RT pts was 7.4 months (95% CI, 3.1-19.1) and the estimated rate at 12 months was 45.9% (95% CI, 28.3-61.8). The median time on treatment for the 41pts who responded to treatment was 8.3 months. Eight pts stopped pirtobrutinib to pursue curative-intent allogeneic SCT and DoR was censored at the last preceding disease assessment. At a median survival follow-up of 18.3 months, the median OS for the entire RT cohort was 12.5 months (95% CI, 6.9-20.5). At 18 months, the OS rate was 44.3% (95% CI, 32.5-55.4). Frequent treatment-emergent adverse events (TEAE) in the RT cohort (n=82) were neutropenia/decreased neutrophil count (29.3%, n=24), fatigue (24.4%, n=20) and diarrhea, dyspnea, thrombocytopenia, and pyrexia (18.3% each, n=15). Common grade ≥3 TEAEs were neutropenia/decreased neutrophil count (23.2%, n=19), thrombocytopenia (11.0%, n=9), plus anemia and sepsis (9.8% each, n=8). Any grade hypertension (3.7%, n=3) or atrial fibrillation (1.2%, n=1) were infrequent. Three pts (3.7%) had treatment-related AEs leading to dose reductions, but no pt had a treatment-related AE leading to pirtobrutinib discontinuation. Analyses of clonality will be presented. Conclusions: Continued follow-up from BRUIN demonstrates encouraging response and OS in pts with RT. Pirtobrutinib remains well-tolerated with low rates of discontinuation and manageable safety profile. While RT remains a challenging diagnosis, pirtobrutinib represents a potential treatment option that warrants further investigation.

Introduction: Chimeric antigen receptor T-cell therapy (CAR-T) has revolutionized the treatment of non-Hodgkin lymphoma (NHL). Despite having an increased risk of NHL, patients with pre-existing autoimmune disease (AID) were excluded from pivotal CAR-T trials due to concerns that CAR-T may exacerbate AID. As a result, there are limited data on the safety and efficacy of CAR-T for NHL in patients with AID. Interestingly, there is also growing evidence that CAR-T can be therapeutically effective for AID, such as in the treatment of systemic lupus erythematosus (SLE). As CAR-T utilization for NHL increases, it is essential to characterize the safety and efficacy of this potentially curative therapy in patients with AID. This study aimed to evaluate the impact of AID on outcomes in patients treated with commercial CD19-targeted CAR-T for NHL. Methods: Following Institutional Review Board approval, we conducted a retrospective analysis of all patients who were treated with commercial CD19-targeted CAR-T for NHL and had a pre-existing AID across the Mayo Clinic Enterprise (Arizona, Florida, and Minnesota) between January 2018 and May 2023. Variables collected included age, gender, NHL type, AID type, and CAR-T product. Efficacy outcomes, including response rates at 6 and 12 months after CAR-T, were collected. Toxicities, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), were collected and analyzed. Our chart review for AID included SLE, sarcoidosis, ulcerative colitis, celiac disease, pernicious anemia, Crohn's disease, psoriasis, Sjogren's syndrome, hypothyroidism (Hashimoto's disease), hyperthyroidism (Graves' disease), rheumatoid arthritis (RA), vasculitis, scleroderma, and mixed connective tissue disease (MCTD). Results: A total of 235 patients who received commercial CD19-targeted CAR-T for NHL across the Mayo Clinic Enterprise were identified (Table 1). Of these 235 patients, 27 had a pre-existing AID and 208 did not. The median age was 66 years (range 39-81) for patients with AID and 59 years (range 18-88) for patients without AID. Over half of the patients were male (59% of patients with AID and 51% of patients without AID). The most common NHL type was diffuse large B cell lymphoma (41% of patients with AID and 56% of patients without AID). Most patients received axicabtagene ciloleucel (85% of patients with AID and 84% of patients without AID). The most common AID was hypothyroidism (81%, n=22), although other conditions were also identified, including RA (11%, n=3), SLE (4%, n=1), pulmonary sarcoidosis (4%, n=1), psoriasis (4%, n=1), and MCTD (4%, n=1). Two patients had more than one AID. Median follow-up was 18 months (range 1-36) for patients with AID and 14 months (range 2-49) for patients without AID. Six months after CAR-T, the complete response (CR) rate was 77.2% and 45.1% in patients with AID and without AID, respectively (p=0.0042). Twelve months after CAR-T, the CR rate was 50% and 31.4% in patients with AID and without AID, respectively (p=0.0801). CRS of any grade occurred in 78% and 88% of patients with and without AID, respectively. ICANS of any grade occurred in 41% and 54% of patients with and without AID, respectively. Conclusion: AID did not appear to adversely impact the safety or efficacy of CAR-T for NHL. Limitations of our study include the small number of patients with AID and the fact that the most common AID was hypothyroidism. Larger studies are warranted to confirm these findings. Additional data are needed to characterize the impact of CAR-T for NHL on AID outcomes and to describe the effect of disease-modifying antirheumatic drugs on NHL outcomes after CAR-T.

Background: Helicobacter pylori (H. pylori) infection plays a critical role in the pathogenesis of gastric MALT lymphoma and its eradication can lead to tumor regression with a complete response (CR) rate of 78% in early-stage disease and a 5-year survival rate > 95%. However, 10% of patients have gastric MALT lymphoma with no detectable H. pylori infection (Zullo et al., J Clin Gastroenterol 2010). There is controversy regarding whether H. pylori-negative gastric MALT patients should receive a trial of antibiotic therapy. The NCCN guideline recommends skipping antibiotics and proceeding directly to radiation therapy. On the other hand, the ESMO guideline recommends H. pylori eradication (HPE) as the first-line therapy for every patient with gastric MALT lymphoma irrespective of H. pylori status. This report aimed to evaluate the effectiveness of H. pylori eradication therapy in patients with limited-stage gastric MALT lymphoma. Methods: A retrospective analysis was performed to identify patients diagnosed with stage IE gastric MALT lymphoma between January 2002 and December 2022. H. pylori infection was determined by immunostaining of gastric mucosa, serology, stool antigen, or urea breath test. H. pylori status was considered positive when at least one of those tests showed positive results and negative when all of the performed test results in that patient were negative. The primary outcome was the CR rate defined as no macroscopic findings of lymphoma and negative biopsy resultsfrom the follow-up endoscopy 3-6 months following completion of treatment. Results: A total of 52 patients were identified; the median age was 68 years (range 52-87), and 29 (55.8%) were male. H. pylori infection was detected in 36.5% (19/52) patients by at least one of the methods - 14 cases by immunostaining, 3 cases by serology, and 1 each by stool antigen and urea breath test. The PCR or FISH for t(11;18) was performed in 10 cases (19.2%) and 2 cases of t(11;18) were detected (both were H. pylori-negative). All 19 H. pylori-positive patients were treated for H. pylori eradication (HPE) and 63% (12/19) achieved a CR. Of the 33 H. pylori-negative patients, 8 (24.2%) received HPE as the initial treatment and 1 (12.5%) responded with a CR. The treatment outcomes after HPE therapy showed the CR rate was significantly higher in H. pylori-positive patients than in H. pylori-negative patients (63.2% vs 12.5%, p=0.033) (Table 1). Only 2 of the 12 H. pylori-positive patients achieving CR have relapsed after a median follow-up of 89.7 months (range 2.9-227.8); the one H. pylori-negative patient that received HPE also remains in CR at 9+ months. The other first-line treatments applied for the 25 H. pylori-negative patients were radiation therapy in 18 (54.5%), single-agent rituximab in 3 (9.0%), surgical resections in 2 (6%), oral chlorambucil in 1 (3%), and observation in 1 (3%) The outcomes are shown in Figure 1. Conclusion: In our United States patient population, the incidence of H. pylori-negative gastric MALT lymphoma was 63%, much higher than previously reported (Zullo et al., J Clin Gastroenterol 2010) and similar to that found by other US investigators (Strati et al. 10.1002/ajh.25447). For limited-stage H. pylori-positive gastric MALT lymphoma, HPE is an effective first-line treatment and should be used. For patients who have no detectable H. pylori infection with multiple methods, the CR rate with HPE is very low in our experience. Although there is likely little harm to trying HPE (as ESMO guidelines suggest), this delays definitive radiation therapy. These data will be useful in patient counseling and treatment decision-making.

Background: The new standard of care for fit patients with refractory or early relapse of diffuse large B-cell lymphoma (DLBCL) is chimeric antigen receptor T-cell (CAR-T) therapy. However, for patients with a relapse ≥12 months after completing frontline therapy, salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell transplant (ASCT) remains the standard of care. There is a need to characterize such patients and their survival in view of the recent shift in treatment paradigm. Methods: Patients with DLBCL that relapsed ≥12 months after R-CHOP or R-CHOP-like frontline therapy who underwent salvage therapy and ASCT at Mayo Clinic or University of Iowa between 07/2000 and 4/2020 were identified from institutional lymphoma and transplant databases. Clinical characteristics, treatment information, and outcome data were abstracted. Progression-free survival (PFS) and overall survival (OS) from the time of ASCT were analyzed using Kaplan-Meier method and Cox proportional hazards models. Statistical analyses were performed in JMP v15. Results: A total of 158 patients with late relapsed DLBCL who underwent salvage chemotherapy and ASCT were identified. Baseline characteristics at relapse/ASCT are shown in Table 1. Median time from frontline therapy completion to 1st relapse was 26.4 months (range 12.0-152.4). Median age at relapse was 63 years (range 19-77), and 96 (61%) patients were male. A minority (3; 3%) had ECOG PS ≥2. 43 (52%) patients had an elevated serum LDH level, 70 (65%) had advanced stage disease, and 12 (11%) had >1 extranodal involvement. Median line of salvage therapy was 1 (range 1-3), and 17 (11%) patients required >1 line of salvage therapy. Best response before ASCT was complete response (CR) in 97 (61%) and partial response (PR) in 61 (39%). Median age at ASCT was 64 years (range 19-78). Median follow-up after ASCT was 91.5 months (95% CI 74.0-103.3). Median PFS and OS were 54.5 (95% CI 31.9-77.8) and 99.8 (95% CI 60.3-144.5) months, respectively. The 2-year PFS and OS rates were 64% (95% CI 56-71) and 81% (95% CI 74-87), respectively. No statistically significant difference in PFS was seen based on age at ASCT, sex, serum LDH, stage, or extranodal site involvement of >1 at relapse (Table 2). However, patients who required > 1 line of salvage therapy, compared to those requiring 1 line of salvage therapy, had significantly inferior PFS (median 6.1 vs 61.8 months, P <0.0001) and OS (17.8 vs 111.7 months, P <0.0004). There was no statistically significant difference in survival in patients who achieved CR vs PR prior to ASCT, with a median PFS of 61.8 vs 37.8 months( P=0.21) and a median OS of 111.7 vs 78.3 months ( P=0.62). Patients who achieved CR after 1 line of salvage therapy had the most favorable PFS and OS, with a median PFS of 65.6 vs 45.4 vs 6.1 vs 7.6 months ( P=0.0004) and a median OS of 133.0 vs 88.9 vs 24.2 vs 17.6 months ( P=0.004) in patients achieving CR after 1 line of salvage therapy vs PR after 1 line of salvage therapy vs CR after >1 line of salvage therapy vs PR after >1 line of salvage therapy, respectively (Table 2). In multivariate Cox regression models adjusted for age at ASCT and sex, patients requiring > 1 line of salvage therapy, compared to those who required 1 line of salvage therapy, had significantly inferior PFS with a hazard ratio (HR) of 3.25 (95% CI 1.82-5.78, P <0.0001) and OS with a HR of 3.50 (95% CI 1.86-6.60, P=0.0001). However, there remained no significant difference in survival based on response status (CR vs PR) with a HR for PFS 0.78 (95% CI 0.52-1.17, P=0.23) and OS 0.93 (95% CI 0.58-1.47, P=0.74). Conclusions: Survival after ASCT was excellent in patients with late relapsed DLBCL achieving CR after 1 line of salvage chemotherapy. Favorable survival outcomes were seen in patients who achieved PR after 1 line of salvage therapy. These data support the current clinical practice of ASCT consolidation in these patients. However, post-ASCT survival was poor in patients who required more than 1 line of salvage chemotherapy, despite achieving a satisfactory response to subsequent lines of salvage therapy. Alternative treatment strategies such as CAR-T therapy should be considered in such patients.

Introduction While chimeric antigen receptor (CAR)-T cell therapy has transformed the management of hematologic malignancies, it requires frequent monitoring for acute toxicities, almost universally achieved through mandatory hospitalizations, therefore utilizing a significant amount of healthcare resources. At Mayo Clinic in Rochester, MN, our standard practice is administering CAR-T cell therapy in the outpatient setting through a multi-disciplinary hospital-based outpatient (HBO) unit and remote patient monitoring (RPM) program. Our CAR-T RPM program consists of in-home, electronic health record-integrated technology to monitor vital signs and neurologic symptoms for 30 days post CAR-T infusion. Here we report the healthcare utilization outcomes of CAR-T patients managed in the outpatient setting enrolled in the RPM program. Methods Patients undergoing FDA-approved CAR-T cell treatment in the outpatient setting and participating in the CAR-T RPM program at Mayo Clinic Rochester were included in this IRB-approved study. Patient characteristics, healthcare utilization metrics, inpatient interventions, and patient satisfaction data regarding the RPM program were reviewed. Length of stay (LOS) includes any hospitalizations for which the admission date falls within the RPM monitoring period (CAR-T cell infusion to day +30), even if the hospitalization continued past day +30. Results A total of 123 patients participated in the CAR-T RPM program and underwent treatment in the outpatient setting. Median age at CAR-T infusion was 63 years (range 22 - 83), and most patients were male (n=78, 63%). Non-Hodgkin lymphoma was the most common diagnosis (n=74, 60%), followed by multiple myeloma (n=47, 38%), ALL (n=1, 1%) and other (n=1, 1%). During the PRM monitoring period, 19 (16%) patients were managed entirely in the outpatient setting. The remaining 104 (84%) patients required at least one hospitalization, with most patients (n=70, 57%) hospitalized only once [26 (21%) patients were hospitalized twice, and 7 (6%) patients were hospitalized 3 times, and 1 (1%) patient hospitalized 4 times during the monitoring period]. When considering the first hospitalization post CAR-T infusion, the median LOS was 6 days (range 2 - 47). When considering all hospitalizations post CAR-T, the median LOS was 8 days (range 2 - 47). Only 7 (6%) patients required an ICU stay, with a mean ICU stay of 0.2 days (standard deviation 0.9). Cytokine release syndrome (CRS) was noted in 92 (75%) of patients at a median of 3 days (range 0 - 18) post CAR-T infusion. All patients with CRS received tocilizumab, at a median of 4 days post CAR-T infusion. Steroids for CRS were administered in 63 (68%) of these patients. Neurotoxicity was reported in 45 (37%) patients at a median of 7 days (range 1 - 19) post CAR-T infusion. During the RPM monitoring period, patients were seen in our HBO unit with a median of 18 outpatient visits (range 4 - 30). Patient survey data, obtained at the end of the RPM monitoring period, were available from 37 patients. The majority of patients felt that the RPM program helped them feel comfortable managing their health at home, were able to reach a team member, and receive an appropriate response promptly. The majority of patients felt comfortable using the RPM equipment and interacting with providers virtually. Overall, 83% of patients were satisfied with the RPM program and 6% were neither satisfied nor dissatisfied. When asked about the reason for disappointment, technical difficulties/issues with the devices were the themes mentioned by the few patients (11%) who were unsatisfied with the RPM program. Conclusion: Despite the complexities and frequent monitoring associated with CAR-T cell therapy, outpatient CAR-T cell treatment is a feasible model of care. As the standard practice at our institution, the CAR-T RPM program was part of the management of nearly all patients undergoing an FDA-approved CAR-T product in the outpatient setting. RPM in the acute setting post CAR-T infusion is a well-received practice initiative by the majority of patients, including a high level of comfort utilizing the RPM equipment and virtual interaction with the RPM providers.