Hilal, Talal

Abstract INTRODUCTION Bispecific antibodies (BsAbs) have emerged as transformative therapies for hematologic malignancies, with several agents now approved for relapsed/refractory acute lymphoblastic leukemia (ALL), multiple myeloma (MM), and non-Hodgkin lymphoma (NHL). These therapies have demonstrated remarkable overall response rates across multiple clinical trials, with some now being evaluated in frontline settings. Recent publications have raised concerns about SPMs following CAR-T cell therapy, with the FDA requiring boxed warnings after reports indicated SPMs rates of up to 5%. However, the incidence of SPMs with BsAbs remains poorly characterized, despite shared mechanisms of T-cell activation. METHODS We conducted a systematic literature search via PubMed to identify peer-reviewed publications reporting clinical trials of FDA-approved BsAbs for hematological malignancies. Included agents were blinatumomab (CD19×CD3), glofitamab, mosunetuzumab, epcoritamab, and odronextamab (all CD20×CD3), as well as elranatamab, teclistamab, and linvoseltamab (BCMA×CD3), and talquetamab (GPRC5DxCD3). Eligible studies included phase I-III trials evaluating BsAbs either as monotherapy or combination therapy, irrespective of prior lines of treatment. Studies published only as abstracts were excluded due to insufficient adverse event reporting. Trials were screened for documentation of SPMs, both from main and supplemental publications. Trials were categorized based on SPMs reporting: “N/A” (insufficient data), “No” (explicit acknowledgment of no SPMs or comprehensive AEs reports with no malignancy entries), and “Yes” (direct reporting of SPMs). Only patients who received BsAbs were included in pooled analyses; comparator or control arms from randomized trials were excluded. For trials reporting patient numbers, median follow-up and SPM counts, we calculated crude incidence rates and cumulative incidence per 100 person-years using estimated total person-years. RESULTS We identified 19 clinical trials encompassing 5,133 patients across ALL (n=5 trials), MM (n=4), and NHL (n=10, including DLBCL and follicular lymphoma). Phase distribution included 5 phase 3 trials and 14 phase 1/2 trials. Most trials (n=16, 84%) evaluated BsAbs as monotherapy. The median number of patients enrolled per trial was 145 (range 54-718; mean 193), with a median follow-up of 14.3 months (range 4.2-43 months; mean 18.3). Four trials (21%) had insufficient adverse event data and were excluded from the analysis. The final pooled cohort analysis included 3,215 patients with available long-term safety data and a cumulative follow-up of 6,270 person-years. Across this cohort, 5 SPMs were reported, corresponding to a crude incidence of 0.16% and a cumulative incidence rate of 0.08 per 100-person years. These included 3 cases reported under “neoplasms benign, malignant and unspecified” in the TOWER trial (1 extramedullary leukemic infiltration, 1 pulmonary leukemic infiltration and 1 acute lymphocytic leukemia), along with 1 lung malignancy and 1 case of Hodgkin's lymphoma both from mosunetuzumab studies. CONCLUSION This analysis suggests a low incidence of SPMs with BsAb therapy compared to CAR-T therapy and appears consistent with expected baseline rates in heavily pretreated hematologic malignancy populations. Notably, some reported cases may represent disease progression rather than true SPMs. However, limited follow-up duration across trials warrants continued long-term surveillance, particularly as agents move to frontline settings where longer survival may reveal delayed malignancies.

Abstract Introduction Histiocytic neoplasms (HN) are a rare, heterogeneous group of hematologic disorders derived from myeloid-dendritic cell lineages. The most common forms include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman disease (RDD). These disorders are driven by recurrent activating mutations in the MAPK pathway, most frequently involving BRAF, MAP2K1, PIK3CA, KRAS, and NRAS. This discovery enabled a major therapeutic advance with the use of BRAF and MEK inhibitors, resulting in durable responses. For patients harboring KRAS mutations, MEK inhibitors (MEKi) remain the primary therapeutic approach. However, the impact of KRAS mutation subtypes on treatment response remains poorly understood. Our study aimed to characterize the spectrum of KRAS mutations in LCH, ECD, and RDD and evaluate the responses to MEKi, providing insights to guide future treatment strategies. Methods We conducted a retrospective review of patients with LCH, ECD, and RDD who were evaluated at Mayo Clinic or University of Alabama at Birmingham. Patients were included if next-generation sequencing identified a KRAS mutation. The response assessment was based on radiographic evaluation under the most recent Histiocyte Society consensus guideline. Results We identified 23 patients with a KRAS mutation: 17 females (73.9%) and 6 males (26.1%), with a median age at diagnosis of 61 years (range, 20–78). RDD accounted for 73.9% (17/23) and ECD for 26.1% (6/23); no KRAS mutations were detected in LCH patients. The most frequent KRAS variants were p.K117N (34.8%), p.G12D (17.4%), p.A146T (13.0%), p.G13C (8.7%), and p.G13D (8.7%), with additional variants including p.T58I, p.A59G, p.A146P, and p.A146V. Mutation distribution differed by disease group: p.G12D was more common in ECD (50%) than RDD (5.9%) (p=0.01), whereas p.K117N occurred in 47.1% of RDD and was absent in ECD. Regarding treatment, 57% (13/23) received MEKi, all initially cobimetinib, with 1 patient switched to trametinib due to progression. Of the 10 patients who did not receive MEKi, 1 was treated with vemurafenib for a concurrent BRAF p.V600E mutation; 3 remained on observation; 2 underwent surgery without recurrence; 3 received other systemic therapies including corticosteroid, methotrexate, rituximab, lenalidomide, or sirolimus; and 1 developed diffuse large B-cell lymphoma, treated with R-CHOP. The overall response rate in the 12 patients on MEKi (excluding 1 patient too early for assessment) was 75%—3 (25%) CR and 6 (50%) PR (including 1 who initially progressed on cobimetinib but responded to trametinib). All 3 non-responders had RDD. Among the 5 patients with p.K117N, 3 had no response to cobimetinib, 1 achieved PR, and 1 achieved CR; notably, 1 non-responder switched to trametinib and achieved PR in 2 months. All 3 patients with codon 146 mutations achieved PR. Of the 2 patients with p.G12D, 1 achieved CR with a co-occurring MAP2K1 mutation, and 1 had no response. No additional genotype–response patterns were observed. Similar heterogeneity has been reported in prior studies. In a phase II cobimetinib trial, an ECD patient with p.R149G achieved PR, whereas another ECD patient with p.G12R and an LCH patient with p.G13C achieved CR in the presence of co-occurring ARAF and NRAS mutations, respectively. A retrospective cohort described an ECD patient with p.K117N achieving PR on dabrafenib and trametinib with a concurrent BRAF mutation and another with p.G12A achieving PR on trametinib. In a multicenter analysis of trametinib, a patient with p.A59T (co-occurring BRAF and NRAS mutations) had no response, whereas another with p.A146P achieved PR. Collectively, these findings, together with our data, underscore that KRAS-mutated histiocytoses exhibit heterogeneous responses to MEKi, likely influenced by variant type and co-mutations. Discussion KRAS mutations represent an important subset of MAPK pathway alterations in HN, although their prevalence varies by disease type and appears extremely rare in LCH, with no cases identified in our cohort. The most common variants include p.K117N and p.G12D, which may be linked to suboptimal response to MEKi in the absence of concurrent MAPK pathway alterations. As MEKi acts downstream, efficacy likely depends on the level of pathway activation conferred by specific KRAS variants. Larger studies are needed to confirm these observations and identify mutation-specific predictors to guide personalized treatment.

Abstract Introduction: Brexucabtagene autoleucel (Brexu-cel) is a CD19-targeted chimeric antigen receptor (CAR-)T cell therapy approved for treatment of relapsed/refractory (r/r) B-ALL. Brexu-cel's approval was founded on data from the ZUMA-3 trial, in which 78 patients (pts) were treated at the pivotal dose of 1x10e6 CAR-T cells/kg, resulting in a complete remission (CR) rate of 73%. Three-year follow-up from ZUMA-3 demonstrated median relapse-free and overall survival (RFS/OS) of 11.6 and 25.6 months (mos) for all treated pts. Amongst responders, the median OS was 60.4 mos for those who did not receive a subsequent allogeneic hematopoietic cell transplant (HCT) (n=43), but only 36.3 months for those who did (n=14). This has led some to conclude that HCT may not be beneficial following brexu-cel therapy for r/r B-ALL; however, it must be noted that 29 (37%) of the pts treated on ZUMA-3 received brexu-cel for post-HCT relapse. T cells collected from individuals who relapse in the post-HCT setting are largely of donor origin, making the CAR-T product comparable to a genetically modified donor lymphocyte infusion (DLI). The immunology at play in this scenario may be different from that in which CAR-T cells are of truly autologous origin. Methods: The Real-World Outcomes Collaborative for CAR-T in ALL (ROCCA) consortium database includes pt characteristics and outcomes of brexu-cel therapy given as standard-of-care across 41 US institutions. We identified pts who achieved an MRD negative (neg) CR by either flow cytometry (minimum sensitivity 10e-4) or NGS following brexu-cel for r/r Ph neg B-ALL and categorized them into three groups with regard to use of HCT: Never HCT, Pre-CAR HCT, or Post-CAR HCT. Pts who received second HCT following brexu-cel for post-HCT relapse (n=9) were excluded. Pt/disease characteristics, RFS, and OS were assessed for each group, landmarked at 73 days after brexu-cel infusion (the median time to consolidative allogeneic HCT). Results: In the ROCCA database we identified 165 pts who achieved MRD neg CR following brexu-cel, amongst whom 69 never underwent HCT, 49 were transplanted pre-CAR (ie, brexu-cel served as a genetically modified DLI), and 47 underwent post-CAR consolidative HCT while in CR. The median follow-up is 373 days. The median age was higher in the Never HCT group (49, range 19-83) in comparison with the Pre-CAR HCT (40, 24-72) and Post-CAR HCT (34, 18-70) groups. Thirty-five percent were >60yo in the Never HCT group vs 20% in the Pre-CAR HCT and 9% in the Post-CAR HCT groups. Ph-like disease was present in 38%, 29%, and 43% of the Never HCT, Pre-CAR HCT, and Post-CAR HCT groups, respectively (p=0.35). No significant differences were observed in pre-apheresis bone marrow blasts, presence of CNS disease at apheresis, prior blinatumomab or inotuzumab treatment, or use of bridging therapy across the groups, though there was a higher prevalence of non-CNS extramedullary disease in the Pre- and Post-CAR HCT groups (32, 39%) vs the Never HCT group (13%) (p=0.004). A minority of pts in all groups were deemed to be in MRD neg CR prior to apheresis (6-20%). Median RFS was 260 days in the Never HCT group and not reached in the Pre- and Post-CAR HCT groups (p=0.002), with respective 1-yr RFS of 38%, 64%, and 67%. Median OS was not reached in any group and was similar for all at 1-yr at 68-79% (p=0.13). Characteristics of those in the Never HCT group who were least likely to relapse included age >60 (OR 0.22, CI 0.07-0.73 vs age 18-39, p=0.024) and those with non-Ph-like B-ALL (OR 0.33, CI 0.12-0.94, vs Ph-like, p=0.037) in univariate analyses. Conclusions: Real-world data regarding outcomes following brexu-cel therapy allow evaluation of the role for consolidative allogeneic HCT, which remains one of the most important unresolved questions in the use of CAR-T therapy for r/r B-ALL. This analysis demonstrates that a first consolidative HCT after achieving MRD neg CR with brexu-cel is associated with a significant decrease in relapse. Additionally, use of brexu-cel for post-HCT relapse is also associated with a significantly lower risk of relapse compared with those who never received an allogeneic HCT. With the current duration of followup, OS is not significantly different across the three groups. These data suggest there is a benefit for relapse-free survival in pts receiving an allogeneic HCT at some point in the course of treatment for r/r Ph neg B-ALL.

Abstract Background: The synergistic mechanisms of BCL-2 inhibitors and CD20-directed antibodies in the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) often lead to deep and durable responses. Although the use of venetoclax-obinutuzumab (Ven-O) in the frontline setting (1L) for CLL/SLL has led to a paradigm shift in the disease management, there are limited data on its efficacy in the relapsed/refractory (R/R) setting. In this study, we evaluated the efficacy and safety of Ven-O in both 1L and R/R CLL among patients treated outside the context of clinical trials at our institution. Methods We used the Mayo Clinic CLL Database to identify patients with CLL who were treated with Ven-O, both in 1L and R/R settings. Patients seen at Mayo Clinic Rochester between 2017 and 2025 were included. Overall survival (OS) was calculated from date of Ven-O initiation until last known alive date. Event-free survival (EFS) was calculated from date of Ven-O initiation until the next line of treatment or last known alive date. Kaplan-Meier methods estimated EFS and OS rates at 1, 3, and 5 years. Cox proportional hazards models were used to explore the association between baseline factors and EFS and OS; results are reported as hazard ratios (HR) and 95% confidence intervals (95%CI). Finally, we compared the OS to the age- and sex-matched general population of the state of Minnesota. Results A total of 154 patients (91 1L, 63 R/R) were included in the study. The median age was 68 years (69 1L, 68 R/R), and 68% were male (64% 1L, 73% R/R). Overall, TP53 disruptions (either del17p by FISH or TP53 mutation) were noted in 22 (15%) patients (9% 1L, 23% R/R). CLL FISH findings demonstrated del11q in 24 (19%) patients (19% 1L, 18% R/R), del13q in 46 (36%) patients (36% 1L, 36% R/R), and trisomy 12 in 21 (16%) patients (16% 1L, 18% R/R). IGHV genes were unmutated in 95 (68%) patients (60% 1L, 80% R/R). The CLL-IPI risk score was high in 54 (51%) patients (51% 1L, 53% R/R) and very-high in 18 (17%) patients (8% 1L, 34% R/R). A total of 121 (89%) patients completed planned treatment (1 year of venetoclax in 73 [90%] 1L and 2 years of venetoclax in 48 [87%] R/R). Median follow-up for the entire cohort was 1.8 years (2.2 1L, 1.5 R/R). Neither median EFS nor OS was reached for the overall cohort or within the 1L and R/R subgroups. The 1, 3, and 5-year EFS estimates for the overall cohort were 91% (86-96%), 85% (78-92%), and 67% (51-89%), respectively; corresponding EFS values for the 1L subgroup were 95% (91-100%), 89% (82-98%), and 67% (47-95%), respectively; and for the R/R subgroup were 85% (76-95%), 77% (65-92%), and 77% (65-92%), respectively. The 1, 3, and 5-year OS estimates were 98% (95-100%), 95% (91-99%), and 88% (76%-100%), respectively; corresponding OS values for the 1L subgroup were 99% (96-100%), 97% (94-100%), and 97% (94-100%) and for the R/R subgroup were 96% (91-100%), 91% (82-100%), and 61% (27-100%), respectively. Univariable analyses showed that TP53 disruption was associated with shorter EFS (HR 3.8, 95%CI 1.4-10.2, p=0.01), although IGHV mutation status was not associated with shorter EFS. A higher level of serum beta-2 microglobulin (HR 1.27, 95%CI 1.01-1.59, p=0.04) and R/R status (HR 4.9, 95%CI 0.9-25.8, p=0.06) were associated with a shorter OS. Interestingly, TP53 mutation status and IGHV mutation status were not associated with inferior OS. There was no difference in the observed and expected OS for both the 1L (p-0.23) and R/R (p=0.14) Ven-O treated cohorts compared to the age- and sex-matched general population of the state of Minnesota. Conclusions Our study shows that Ven-O is a well-tolerated regimen with demonstration of durable treatment responses both in the 1L and R/R groups, when used outside the context of a clinical trial. To the best of our knowledge, these data for the first time demonstrate no difference in OS of patients treated with Ven-O compared to age- and sex-matched general population, in both the 1L and R/R settings.

Abstract Introduction: Langerhans Cell Histiocytosis (LCH) is a rare histiocytic neoplasm, with approximately 90% of patients exhibiting alterations in the MAPK pathway. BRAF and MEK inhibitors have shown promising results in treating MAPK pathway-altered LCH. However, treatment interruptions due to adverse effects are common, and limited access to targeted therapies complicates care globally. While chemotherapy remains a common treatment for LCH, the outcomes for patients with MAPK pathway-altered LCH specifically receiving chemotherapy are still unclear. Methods: This multi-institutional international retrospective cohort study analyzed adult patients with BRAF or MAP2K (gain-of-function, GOF) altered LCH that were consecutively seen at Mayo Clinic, MN, AZ, and FL, University of Alabama at Birmingham, and Peking Union Medical College Hospital in China between 2007 and 2024. All patients who were included in this study were treated with chemotherapy, and those who have received targeted therapies or other modalities of frontline treatment were excluded. All time-to-event analyses were performed from the frontline therapy initiation, using the Kaplan-Meier method. Progression-free survival (PFS) included death and progression as events and was measured from the time of treatment initiation. The response assessment was based on radiographic evaluation in accordance with the most recent Histiocyte Society consensus guideline. Risk organ involvement was defined as disease involving the liver, spleen, bone marrow or central nervous system. Results: A total of 63 patients with LCH were included. The median age of the population was 34 years (range: 27-43), and males were 59%. Risk organ involvement was seen in 44 (70%) of patients and multisystemic LCH was observed in 48 (76%) patients. Among the 63 patients, BRAF gain-of-function alterations were observed in 79%, MAP2K mutations in 19%, and BRAF fusions in 2%. Of the BRAF gain-of-function alterations, BRAFV600E mutation was seen in 64% patients and [p.N486_P490del] deletion in 36%. There was no significant difference in organ involvement (single-system versus multisystem) or risk organ involvement between patients with BRAF and MAP2K alterations. All 63 patients received systemic therapy with chemotherapy and the regimens included Cytarabine (n=43), Cladribine (n=5), Etoposide (n=1), Methotrexate (n=1), and combined Methotrexate and Cytarabine (n=13). The median follow-up for the entire cohort was 3.8 years (range 3.2–5.0 years), with similar durations observed in patients with single-system vs. multisystem involvement and those with risk-organ involvement vs. no risk-organ involvement. The overall response rate among patients who received chemotherapy was 89%, with complete responses in 15 patients (26%) and partial responses in 40 patients (64.5%). The median progression-free survival (PFS) for the entire cohort was 2.61 years (95% CI: 2.06–NA). The 3-year PFS did not significantly differ based on risk organ involvement: 50.6% (95% CI: 36–71) for patients with risk organ involvement versus 47.4% (95% CI: 28–81) for those without, p=0.52. Patients with single-system disease experienced longer PFS compared to those with multisystem disease; the 3-year PFS was 80.2% (95% CI: 58.7–100) versus 42.2% (95% CI: 29–61.5), respectively, p=0.04. Conclusions: Our results indicate that LCH patients with a GOF alteration in the MAPK pathway derive significant clinical benefit from chemotherapy, achieving deep and durable responses. Therefore, patients should not be excluded from treatment due to the absence of targeted therapies, as they can still attain substantial responses and clinical improvement with chemotherapy, even in the context of MAPK pathway-driven disease.

Abstract Introduction Chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies have emerged as transformative options for patients with relapsed or refractory multiple myeloma (MM). Both modalities commonly target B-cell maturation antigen (BCMA) and have demonstrated high overall response rates in pretreated populations ranging from 65-83%. However, the optimal sequencing and comparative effectiveness of these two novel therapies remain unclear. Understanding their treatment outcomes is critical to inform treatment decisions in this rapidly evolving therapeutic landscape. Method A retrospective cohort study was conducted using TriNetX, a global federated health research network that provides access to electronic medical records from approximately 132 million patients, primarily in the United States. Adult patients (≥18 years) diagnosed with relapsed or refractory MM between January 1, 2022, and January 1, 2024, were identified using ICD-10-CM codes. Patients were categorized into two cohorts: those who received CAR T-cell therapy including idecabtagene vicleucel and ciltacabtagene autoleucel and those who received bispecific antibodies including teclistamab and elranatamab. Propensity score matching (1:1) using nearest neighbor matching with a 0.1 pooled standard deviation caliper was performed for demographics, comorbidities, prior stem cell transplantation, medications, and performance status. Study outcomes included 1-year rates of all-cause mortality, all-cause hospitalization, cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), anemia, neutropenia, thrombocytopenia, sepsis, and pneumonia. Statistical analyses were conducted on the TriNetX platform, with significance set at P<0.05 (two-sided). TriNetX calculates hazard ratios (HRs) and cumulative incidences (CIs) using R survival package version 3.2-3 with the proportional hazard assumption tested using Schoenfeld residuals. This study does not require Institutional Review Board review or informed consent due to the use of de-identified data. Results Our study identified 2,023 patients, including 911 patients who received CAR T-cell therapy and 1,112 who received bispecific antibiotics. After propensity score matching (PSM), each cohort included 649 patients. The CAR T-cell therapy group had a mean age of 66.8 ± 8.4 years, with 41.4% female, 68.0% White, 20.6% African American, and 2.3% Asian. The bispecific antibody group had a mean age of 66.3 ± 9.3 years, with 41.1% female, 67.3% White, 21.1% African American, and 2.2% Asian. CAR T-cell therapy group experienced a 64% lower risk of all-cause mortality (HR 0.36; 95% CI, 0.26–0.48) and a 44% lower risk of all-cause ICU admission (HR 0.56; 95% CI, 0.42–0.75) compared with bispecific antibodies group. However, CAR T-cell therapy group was associated with higher risk of CRS (HR: 1.91; 95% CI: 1.57–2.31), ICANS (HR: 1.50; 95% CI: 1.12–2.01), neutropenia (HR: 2.32; 95% CI: 1.96–2.76), and thrombocytopenia (HR: 1.80; 95% CI: 1.43–2.28) compared to bispecific antibodies group. There was no significant difference observed in anemia (HR: 0.96; 95% CI: 0.82–1.13) between these two treatment groups. Additionally, CAR T-cell therapy group was associated with 46% lower risk of sepsis (HR: 0.54; 95% CI: 0.39–0.75) and 68% lower risk of pneumonia (HR: 0.32; 95% CI: 0.17–0.61) compared to bispecific antibodies group. ConclusionIn this real-world analysis, CAR T-cell therapy demonstrated a substantial lower mortality and reduced ICU utilization compared with bispecific antibodies in patients with relapsed or refractory MM, despite its higher risks of CRS, ICANS, and hematologic toxicities. An important limitation of our study is the lack of data on the number of prior lines of therapy, which likely differed between groups, as bispecific antibodies are typically used in the fourth line or beyond, while CAR T-cell therapies are approved to be used as the second line. This discrepancy may have influenced both mortality and infection rates. Despite the limitation, our findings underscore the need for prospective clinical trials directly comparing CAR T-cell therapy and bispecific antibodies to validate these observations and define the optimal sequencing of these modalities. Furthermore, research into predictive biomarkers and personalized selection algorithms will be crucial to optimize treatment decisions in this rapidly evolving therapeutic landscape.

Abstract Background Adult xanthogranuloma (AXG) is a rare clonal histiocytic neoplasm (HN) with a poorly defined mutational landscape. Clinically and immunophenotypically, AXG can resemble other HNs such as Erdheim-Chester Disease (ECD) which frequently harbor MAPK pathway alterations and carry BRAF V600E mutations in close to 50% of cases. However, due to the rarity of AXG, the prevalence of the BRAF V600E mutation and the broader mutational landscape is not well known. In this study, we characterize the mutational profile of AXG. Methods We conducted a retrospective analysis of patients diagnosed with AXG at our institution between January 1, 2016, and July 15, 2025. The study was approved by the institutional review board. To ensure inclusion of true AXG cases, only patients with a confirmed histopathologic diagnosis and without multisystemic involvement or characteristic imaging findings of ECD, such as symmetric long bone osteosclerosis, were included. BRAF alterations were identified by immunohistochemistry (IHC) and/or next-generation sequencing (NGS). We also performed an extensive literature review of mutational studies in AXG and included cases that underwent comprehensive NGS. Results Seventeen patients with AXG were identified. The median age at diagnosis was 40 years (range: 18–75 years). Out of the 17 patients, 11 (65%) reported the face as the primary site of disease, and 11 (65%) had solitary lesions. Of the 17 patients, 13 (76%) underwent BRAF V600E IHC staining, and none tested positive. Twelve (71%) patients had tissue samples analyzed via NGS, and none exhibited the BRAF V600E mutation. Eight of the 12 (67%) patients with NGS testing harbored other alterations involving the MAPK pathway. These included BRAF fusions (n=3), KRAS mutations (n=2), and individual cases with TRAF7 mutation, ALK1 fusion and FGFR1 fusion. One patient was found to have a mutation in WRN, which is not previously reported in AXG. Three patients had no identifiable pathogenic alterations on NGS. Ten patients were monitored without treatment, 2 underwent surgical resections and 3 received chemotherapy (1 had a complete response [CR], 2 achieved a partial response). One patient with FGFR1 fusion was treated with pemigatinib and achieved a CR for over 3 years. One patient with TRAF mutation obtained a CR after treatment with rituximab. We also identified 51 cases of AXG with adequate mutational testing reported in the literature, which reported findings similar to ours. In a retrospective study from France involving 29 patients, MAPK alterations were observed in 55% of cases: however, only 10% harbored BRAF V600E mutations (1). Another analysis of 270 patients with various HN subtypes included 13 individuals with AXG, none had BRAF mutations. MAP2K1 mutations were seen in 31% of patients (2). Taken together, across a combined cohort of 68 AXG patients, the most common alterations were: KRAS mutations (16%), fusions (14%), MAP2K1 mutations (7%) and BRAF V600E (6%). Among fusions, the most involved gene was BRAF (50%), and GAB2 was the most common fusion partner (n=2). In total, 59% of patients had MAPK alterations. These findings collectively underscore the diverse mutational landscape of AXG and highlight the rarity of BRAF V600E mutations relative to closely related HNs. Conclusion We present a series of AXG cases with mutational profiling, from our institution and the published literature. We demonstrate that MAPK alterations are frequently observed in AXG and are driven by heterogeneous mutations. In contrast to other HNs where BRAF V600E mutations are common, we identified no such mutations in our cohort and found only rare cases in the literature. Our institutional data, along with findings from the existing literature, suggest that AXG may have a distinct molecular profile compared to other HNs. A deeper understanding of its mutational landscape may offer insights into disease biology and identify therapeutic targets. ReferencesAnnabi E, Mahévas T, Chasset et al. Clinical, Histopathologic, and Molecular Features and Treatment of Multiple Xanthogranuloma in Adults. JAMA Dermatol. 2025;161(7):765-768. doi:10.1001/jamadermatol.2025.0886.Durham BH, Lopez Rodrigo E, Picarsic J, et al. Activating mutations in CSF1R and additional receptor tyrosine kinases in histiocytic neoplasms. Nat Med. 2019;25(12):1839-1842. doi:10.1038/s41591-019-0653-6

Abstract Background Chimeric-antigen-receptor (CAR) T-cell therapy has transformed outcomes for relapsed or refractory hematologic malignancies, yet early identification of patients at highest risk for death remains elusive. A prognostic model that leverages only the information routinely available at the time of CAR-T evaluationcould guide pre-infusion counseling, intensity of follow-up, and resource allocation. Methods We analyzed a prospectively maintained cohort of CAR-T recipients treated at Mayo Clinic to develop and test our model. For each patient, data (vital signs, lab results, cardiac assessments [ECG and echocardiography], and PET/CT images) from initial CAR-T evaluation (up to 60 days prior to CAR-T infusion) was considered. Vital signs and labs were left un-imputed, while ECG, echocardiographic parameters, and PET/CT features were forward-filled from the preceding 60 days. Each patient-day was labeled as “outcome present” or “no outcome,” enabling supervised training of gradient-boosting models to predict overall survival (OS) at 6 months post CAR-T infusion. Model performance was evaluated using the area under the ROC curve (AUC) with 10,000-fold bootstrapping with data shuffling between each iteration to derive confidence intervals for stability. To enhance interpretability, we also developed a simplified model using the top 19 features (determined by Shapley value-based importance), aiming to preserve predictive accuracy with a smaller feature set. Results A total of 570 CAR-T cell treated patients were included in this study (476 patients in the training cohort and 94 patients in the validation cohort). The median age was 64 years and 61% males. The primary diagnoses were B-cell lymphoma (324 patients) and multiple myeloma (246 patients). A total of 4,851 individual vital-sign readings, 11,781 laboratory measurements were included. PET/CT images were available in 318 patients. The ML model demonstrated high discriminative ability for predicting OS at 6 months post CAR-T infusion. Vital signs alone produced a mean AUC of 0.63; radiomics features alone produced a mean AUC of 0.71, while laboratory tests alone produced a mean AUC of 0.84. The features most contributory to each single-modality model were then combined into a simplified multimodal model with a total of 19 features, which produced a mean AUC of 0.87, with a 95% CI of 0.73 - 0.97. The 19 features included in the simplified model were: LDH, ferritin, uric acid, eosinophils, fibrinogen, D-dimer, heart rate, mean arterial blood pressure, QTc, QT interval, and the radiomics features of sphericity, first-order Kurtosis, first-order mean, first-order energy, first-order total energy, shape maximum2D diameter (sagittal plane), SUV CoV, SUVp90, shape flatness. This multimodal predictive model was then applied to the validation cohort (uninvolved with model training or testing), which produced an AUC of 0.93, with a 95% CI of 0.84 - 0.98. Conclusions Our ML-driven approach successfully predicts overall survival 6 months post CAR-T infusion, highlighting those individuals at most risk of poor outcomes at the time of CAR-T evaluation. The strong performance of the multimodal version of the model suggests that each data domain contributes complementary resolving power, and by including novel data types, such as PET CT radiomics features, the most accurate predictions could be realized. By providing accurate, near-real-time risk stratification for poor outcomes within 6 months of CAR-T infusion, the model could facilitate proactive patient management. Prospective studies of the integration of this ML model into CAR-T treatment workflows will be crucial to confirm its clinical benefits and to facilitate its adoption in practice.

Abstract Background:Erdheim-Chester Disease (ECD) is a rare, incurable histiocytic neoplasm. Since its recognition in 1930, our understanding of ECD's pathophysiology has evolved. The identification of its clonal nature after 2015 established ECD as a cancer, prompting increased disease awareness and treatment advances. Targeted therapies show promising responses, but changes in ECD mortality over time have not been extensively documented. Methods:A multi-institutional retrospective cohort study analyzed adults with ECD consecutively seen at Mayo Clinic MN, AZ, and FL and the University of Alabama at Birmingham between 2007 and 2024. Clinical and prognostic data were abstracted. Overall survival was estimated using the Kaplan-Meier method and compared to expected survival using U.S. Census data, based on age at diagnosis (by calendar year), date of diagnosis, and sex. Standardized mortality ratios (SMRs) were calculated by dividing the number of observed deaths in the study population by the expected number of deaths using U.S. population data. Risk of death was compared by date of diagnosis (pre- and post-2015) using Cox proportional hazards analysis. Statistical analysis was performed with R software. Results:A total of 159 ECD patients were included (median age 58 years [range 19-82], 65% male). Forty-nine patients were diagnosed between 1990-2014 and 110 between 2015-2024. Median follow-up for the entire cohort was 4.0 years (95% CI: 3.2-4.4). Median follow-up for those diagnosed between 1990-2014 was 10.4 years (CI: 3.2-16.8), compared to 3.5 years (CI: 3.0-4.2) for those diagnosed between 2015-2024. The 5-year overall survival rate was 80% (95% CI: 72-88). Patients with ECD had an increase in mortality over expected, with 28 deaths compared to an expected 11.2, an SMR of 2.5 (95% CI: 1.7-3.6, p<0.001). Of 17 patients with an identified cause of death, death was attributable to ECD in 11 (65%), secondary malignancy in 1 (7%), and unrelated causes in 5 (29%). Cause of death was unknown in 11 patients. Among deaths, 11 (39%) were treated with targeted therapy, 8 (29%) with chemotherapy, and 1 (4%) received both. One patient (4%) received steroids, 1 received immunomodulator and targeted therapy (4%), and 6 (21%) received no disease-directed therapy. Of the patients whose death was related to ECD, 10 (91%) had multisystem disease. For 49 patients diagnosed pre-2015, 14 deaths occurred during the follow-up, significantly higher than the expected 5.2 deaths based on U.S. population data (SMR of 2.7 [95% CI: 1.5-4.4, p=0.001]). Among those diagnosed between 2015 and 2024, 14 deaths occurred, compared to expected 6.1 (SMR of 2.3 [95% CI: 1.3-3.8, p=0.006]). In an age- and sex-adjusted Cox proportional hazards model, diagnosis after 2015 vs. diagnosis prior to 2015 yielded a hazard ratio of 0.59 (95% CI: 0.27-1.31, p=0.19). Conclusion:The mortality rate of ECD patients remains higher than the general population, despite advancements in disease recognition and development of targeted therapies. While our data suggest a possible trend toward improved survival among patients diagnosed after 2015, we did not find statistically significant evidence of decreased mortality compared to those diagnosed prior to 2015. Larger cohorts with longer follow-up periods are needed to draw definitive conclusions regarding mortality.

Abstract Background: Glofit, a CD20/CD3 bispecific antibody, has shown efficacy in prospective trials, including the Phase III STARGLO study evaluating glofit plus gemcitabine/oxaliplatin (GemOx) in transplant-ineligible patients (pts) with R/R large B-cell lymphoma (BCL). However, concerns raised by the FDA's Oncology Drug Advisory Committee regarding the generalizability of the STARGLO data to U.S. pts underscore the need for real-world evidence. We report real-world outcomes of Glofit-GemOx in U.S. pts with R/R aggressive BCL. Methods: We conducted a multicenter retrospective review across 8 U.S. academic centers, identifying 31 pts with R/R aggressive BCL treated with Glofit-GemOx outside clinical trials. Baseline characteristics, treatment history, and outcomes were abstracted from medical records. Results: At Glofit-GemOx initiation: median age was 72 years (range, 34–88); 90% had stage III/IV disease. Histologic subtypes included DLBCL in 58% (n=18), high-grade BCL in 29% (n=9), PTLD/DLBCL in 6.5% (n=2), follicular lymphoma (FL) grade 3B in 3.2% (n=1), and Burkitt lymphoma (BL) in 3.2% (n=1). Germinal center B-cell phenotype was seen in 80% of evaluable cases. Double- (n=8) or triple-hit (n=1) cytogenetics were observed in 31% (n=9). Elevated LDH was present in 74%, and 16% had B symptoms. Median ECOG performance status was 1 (range, 0–3), and 23% (n=7) had received prior CAR T-cell therapy. Pre-treatment biopsy was performed in 77% (n=24) with CD20 expression tested in 74% (n=23). CD20 expression was negative in 3 pts by flow cytometry and/or immunohistochemistry. Pts received a median 1 prior line of therapy (range, 0-6); Glofit-GemOx was administered as 1L in 7% (n=2), and 2L in 58% (n=18). Median 4 cycles (range, 1-11); both 1L pts had prior FL (1 and 3 prior lines for FL). Twelve pts remain on therapy, 2 on Glofit monotherapy. Four pts were unevaluable (2 death pre-assessment; 2 pending evaluation). Among 27 evaluable pts, ORR was 78% (21/27) and CR rate was 41% (11/27). Among CD20- negative cases on pre- Glofit-GemOx biopsy (n=3), ORR was 33% (1/3), with 1 CR lasting 3.5 months. Of 11 pts who progressed on Glofit-GemOx, 6 were rebiopsied; 1 showed CD20 loss, 1 was previously CD20-negative. Among the 24 pts who received Glofit-GemOx as destination therapy, ORR of 75% (15/20 evaluable). Among pts with prior CAR T (n=7), the ORR and CR rate were both 43% (3/7). None received Glofit-GemOx within 30 days of CAR T-cell infusion; 4 received within 6 mo; 2 of whom achieved CR. Seven pts (24%) received Glofit-GemOx as bridging to CAR T. ORR pre-CAR T was 86% (6/7); 4 pt successfully proceeded to CAR T, 2 are pending infusion, and 1 progressed after 2 cycles and transitioned to alternate therapy. Three pts were evaluable post-CAR T with an ORR of 100% (3/3) and CR rate of 67% (2/3). At data cutoff, 23/31 pts were alive. Full PFS and OS data will be presented at ASH. Notable individual responses included a patient with relapsed BL post–DA-EPOCH-R who received Glofit-GemOx as 2L therapy and achieved a 6 mo CR without consolidation before progression. Another patient treated with Glofit-GemOx in the 7L setting after prior allogeneic transplant achieved a 3 mo CR prior to progression. CRS occurred in 58% (18/31), with grade ≥3 in 13% (4/31), including 2 possible treatment-related deaths. One occurred in a frail patient after the 1st dose, though neutropenic fever was present prior to Glofit administration. The second followed influenza A infection, respiratory failure, and possible grade 4 ICANS after the 2nd dose; attribution to CRS vs. infection was unclear. ICANS occurred in 10% (3/31), with one possible grade ≥3 case. Conclusions: This is the first U.S.-based real-world analysis of Glofit-GemOx, including more U.S. pts than the STARGLO trial, appear to demonstrate comparable response rates, potentially supporting its use as both bridging and destination therapy. Notable toxicities, including CRS, were observed, with 2 possible treatment-related deaths, with plausible alternate non-treatment related causes. Favorable responses were seen in bridging therapy and high-risk subgroups (transformed, HGBCL) which were excluded in the STARGLO trial. These findings support the real-world utility of Glofit-GemOx in the management of R/R aggressive BCL but underscore the need for caution due to associated toxicities. Further real-world and prospective evaluation are warranted, particularly in rare subgroups and as bridging therapy.