Alkhateeb, Hassan B.

12011 Background: Patients (pts) with high HCT-Comorbidity Index scores (HCT-CI of ≥3), older age (≥65 years), and/or who are frail per gait speed (<0.8 meters/second) have increased morbidity and mortality after allo-HCT compared to younger and healthier counterparts. We report the phase II analysis (PIIA) and interim phase III primary outcome analysis (PIIIA) of a seamless phase II/III prospective, randomized clinical trial conducted at 11 transplant centers to test new approaches to improve quality of life (QOL) in this population. Methods: Phase II compared specialist-administered supportive and palliative care (SPC), patient-administered management of comorbidities (MC, e.g. physical exercise, stress reduction, etc), both (SPC+MC), and usual care (UC) for change in Functional Assessment of Cancer Therapy – Bone Marrow Transplantation (FACT-BMT) QOL scores from baseline to day 90 (D90). Pts deceased prior to D90 were assigned FACT-BMT score=0. The winning phase II arm moved forward versus UC in phase III. Results: PIIA was done after enrolling 35 pts to each of the 4 study arms. Calculating the difference between FACT-BMT scores on D90 minus baseline, excluding missing data, indicated that only SPC resulted in a small improvement in QOL compared to either MC or SPC+MC (Table); hence SPC was the winning phase II arm. The PIIIA was conducted after enrolling 158 SPC pts and 153 UC pts. The SPC and UC arms were well balanced with median age (both 68 years), HCT-CI ≥3 (49% vs 55%), frailty per gait speed (13% vs 12%), female sex (41% vs 34%), non-white race (9.5% vs 11.5%), and Hispanic or unreported ethnicity (7.7% vs 5.7%), respectively. After median follow-up of 362 days, 45 pts had died in each arm. The mean QOL difference between D90 and baseline was 2.83 for SPC and 4.27 for UC (difference of differences, -1.44, 95% CI of difference, -5.03 to 2.14, p=0.43). Fitting a generalized linear model that included baseline, D30, and D90 values and testing the null hypothesis that the slope of scores differs between SPC and UC resulted in p=0.85. Using the Kaplan Meier method, no difference in survival was observed across arms (HR 1.13 [0.75-1.73]). Conclusions: Specialist-administered palliative care showed no meaningful improvement in QOL, nor a survival advantage, compared to usual care in frail, older and comorbid allo-HCT recipients, resulting in the cessation of this Phase II/III trial. Analysis of the whole patient population for primary and secondary outcomes is in progress. Clinical trial information: NCT03870750 . Change in FACT-BMT (D90 value minus baseline value) comparing the 4 arms of phase II. Group Mean difference (sd) Median difference (range) SPC (n=28) -2.93 (28.52) 0.25 (-102 to 38.22) CM (n=18) -18.37 (33.80) -9.50 (-98.33 to 11) SPC+CM (n=27) -15.76 (32.69) -7.67 (-90 to 32)

e19008 Background: Cytokine release syndrome (CRS) is typically reversible in CAR-T therapy, while hyperinflammatory syndromes like macrophage activation-like syndrome (MAS-L) and high-grade immune effector cell-associated hemophagocytic syndrome (IEC-HS) are associated with significant morbidity and mortality. Early interventions are critical for improving outcomes. We aim to analyze clinical cytokine assays and cellular phenotypes early in hyperinflammatory syndromes to identify profiles for severe cases to inform management decisions. Methods: This study included 113 CAR-T patients (pt) (September 2019-March 2024) with cytokine profiles (CP) performed at the second tocilizumab dose or with suspected hyperinflammatory states (CP1), followed by assessments at 24 hours (CP24) and 48 hours (CP48). 52 pts consented to blood (PB) and bone marrow (BM) cell immune phenotyping at pre-treatment (pre-LD) and day 1 for PB. Results: Among the 113 pts, CRS pts (N=74), when compared to MAS-L(N=19) & IEC-HS (N=20) at CP1, had lower levels of TNF (median in pg/mL; 31, 62.9, 47.7) , IL-18 (794, 1353, 2011), and MCP-1 (689, 2722, 2485.5). While MAS-L and IEC-HS had similar CP1 profiles, CP24 and CP48 differed between them: TNF & MCP-1 levels decreased in MAS-L but remained elevated or increased in IEC-HS. IL-18 was stable in MAS-L but increased steadily daily in IEC-HS. Infections were more frequent in IEC-HS (CRS: 43%; MAS-L: 58%; IEC-HS: 85%; p=0.002). Notably, patients who died with persistent E. faecium bacteremia had higher IL-18 in CP48. In the 52 pts with cell phenotypes available by flow, 33 had CRS, 18 MAS-L and 8 IEC-HS. The correlation between cell phenotypes and cytokine levels showed that elevated TNF at CP1 correlated with increased non-classical monocytes in pre-LD BM and higher NK and NK-T cells in pre-LD PB. Similarly, elevated IL-18 CP48 levels correlated with increased CD8 T-cells, NK-T cells, and intermediate monocytes in pre-LD PB, as well as increased NK cells at both pre-LD and day 1 (Table). Conclusions: We report distinct cytokine profiles in IEC-HS early in the inflammatory course post-CAR-T therapy. These elevated cytokines correlate with specific immune cell subsets, including BM-resident monocytes, intermediate monocytes with heightened cytokine trafficking and inflammatory capacity. This study demonstrates the feasibility for identifying potential biomarkers for early risk stratification and targeted interventions. Cytokine Sample source Immune cells R P value TNF CP1 BM pre-LD Non-classical monocytes (CD14loCD16+) 0.38 0.025 PB pre-LD Monocytes (All) 0.47 0.022 NK cells (CD56+CD16+) 0.34 0.024 NK-T cells (CD3+CD56+CD16-) 0.29 0.04 IL-18 CP48 PB pre-LD CD8+ T-cells 0.59 0.0093 NK-T cells (CD3+CD56+CD16-) 0.53 0.023 Intermediate monocytes (CD14+CD16+) 0.58 0.012 PB pre-LD NK cells (CD56+CD16+) 0.56 0.49 0.015 0.024

Abstract RATIONALE: Allogeneic hematopoietic stem cell transplant (alloHSCT) is the only curative therapy for multiple hematological malignancies and bone marrow failure syndromes. Graft versus host disease (GvHD), remains one of the leading causes of morbidity and mortality. Bronchiolitis obliterans syndrome (BOS) is the canonical manifestation of chronic GvHD of the lungs, occurring in 3-10% of alloHSCT recipients and conferring poor prognosis. There has been a recent paradigm shift towards using post-transplant cyclophosphamide (PTCy) for GvHD prophylaxis resulting in dramatic decreases in both acute and chronic GvHD compared to traditional regimens using methotrexate and tacrolimus. The effect of PTCy on the development of BOS is not well-studied. METHODS: We performed a retrospective cohort study comparing the cumulative incidence of BOS between 93 patients receiving PTCy and 154 patients receiving non-PTCy containing regimens for GvHD prophylaxis between 2015 and 2023 at a single center (Mayo Clinic, Rochester, MN). Patients were included if they were ever diagnosed with BOS or if they survived and were followed for at least 1 year. BOS was diagnosed using 2014 National Institutes of Health criteria. Patients who met 3 of 4 diagnostic criteria were included if a clinical diagnosis of BOS was made. We performed a competing risks time-to-event analysis to compare the incidence of BOS (or death) between the two cohorts. Outcomes were not adjusted for HSCT type (related, unrelated, or haploidentical [HID]) due to a high degree of collinearity with GvHD prophylaxis strategy. RESULTS: Combined cohorts were median age 55 (40-63), 56% male, and 43% ever smokers. Transplants involved HID donors (59% of PTCy cohort, zero non-PTCy), matched related (10% of PTCy, 44% of non-PTCy), matched unrelated (20% of PTCy, 51% of non-PTCy), and mismatched unrelated donors (11% of PTCy, 5% of non-PTCy). Three-year cumulative incidences of BOS among PTCy and non-PTCy recipients were 7% and 14%, respectively (subdistribution HR 0.52 [95% CI 0.21-1.29], P=0.159). For those who received PTCy, incidence of GvHD was smaller (subdistribution HR 0.64 [95% CI 0.46-0.99], P=0.006) with fewer organs involved (1 versus 2, P=&lt;0.0001) and fewer immunosuppressive therapies employed for treatment (2.0 versus 2.5, P=0.01). CONCLUSION: PTCy may reduce risk of BOS among patients undergoing HSCT. Findings are limited by important differences between the cohorts, such as HCT type, and by small sample size. As PTCy is now increasingly used for non-HID transplants, future studies are needed to examine the effect of PTCy on the development of BOS.

Background/Objectives: DDX41, DEAD-box RNA helicase 41 gene located on chromosome 5q25.3, is one of the most mutated genes in patients with germline predisposition to myeloid neoplasms. Germline and somatic mutations often have different locations and patterns of mutation, with some hotspots displaying diversity based on ethnicity. We aimed to explore clinical outcomes in patients with various DDX41 hot-spot mutations. Methods: This was a retrospective study of patients at Mayo Clinic with DDX41 mutation identified through Next Generation Sequencing (NGS) between 2018 and 2024. We completed unadjusted comparisons using continuous or categorical variables, and survival rates were assessed using the Kaplan–Meier method and cox regression analysis. Results: Overall survival appears to be higher in those with p.M1| when compared to p.Asp140GlyFs*2 and p.Arg525His, with comparable survival between p.Arg525His and p.Asp140GlyFs*2. Among males with p.M1| who underwent bone marrow transplant, those who underwent bone marrow transplant appeared to have lower survival rates, although not statistically significant. Our study was limited by a small sample size, therefore limiting our ability to reach significance. Conclusions: Our findings suggest potential implications for clinical outcomes based on DDX41 mutation hot-spots.

Abstract Allogeneic hematopoietic stem cell transplant (alloHCT) is considered for all patients with myeloid neoplasms (MNs) harboring TP53 mutations (TP53mut). The aim of this international study across 7 transplant centers in the United States and Australia was to identify factors associated with improved post-alloHCT survival. Of 134 TP53mut MN cases who underwent alloHCT, 80% harbored complex karyotype; 94% of TP53 variants were localized to the DNA-binding domain (DBD). Most common comutations were ASXL1 (7%), TET2 (7%), and DNMT3A (6%). Median post-HCT survival was 1.03 years, and overall survival (OS) at 1 year, 2 years, and 3 years was 51.4%, 35.1%, and 25.1%, respectively. A total of 103 cases (76.9%) met the International Consensus Classification (ICC) criteria for MN with mutated TP53 (referred to as ICC-defined TP53mut MN hereafter). The 3-year OS of ICC-defined TP53mut was significantly shorter compared with that of other TP53mut MNs (3-year OS, 16.9% vs 54.9%; P = .002). ICC-defined TP53mut MNs was independently associated with inferior OS (hazard ratio [HR], 2.62; P = .019). The presence of non-DBD TP53mut only (HR, 3.40; P = .005), DNMT3A comutation (HR, 2.64; P = .016), and pre-alloHCT bone marrow blasts ≥5% (HR, 2.76; P = .006) was independently associated with inferior relapse-free survival (RFS), whereas melphalan-based conditioning was associated with superior RFS (HR, 0.52; P = .005). Combining these variables, we constructed a hierarchical model that stratified patients into low-, intermediate-, and high-risk categories with 1-year RFS of 81.3%, 31.3%, and 6.7%, respectively (P &lt; .001). In conclusion, a subset of MN harboring TP53mut who have low blasts pre-alloHCT and received melphalan-based conditioning derived long-term benefit from alloHCT.

Abstract This retrospective analysis aimed to provide evidence-based risk stratification of TP53-mutated (TP53mut) myeloid neoplasms (MNs). Of 580 MNs harboring TP53mut with variant allele frequency (VAF) ≥2%, 219 (37.8%), 194 (33.4%), 92 (15.9%), and 75 (12.9%) were classified as acute myeloid leukemia (AML), myelodysplastic syndrome (MDS) with low blasts (MDS-LB), MDS with excess blasts (MDS-EB)-2, and -EB1 according to the revised fourth edition of the World Health Organization (WHO) classification, respectively. Hierarchical analysis identified the following 4 risk groups with distinct survival: (1) MDS-LB, (2) MDS-EB1/EB2/AML VAF &lt;10%, (3) MDS-EB1/EB2 VAF ≥10%, and (4) AML VAF ≥10%. We next evaluated the impact of allelic status, VAF, and complex karyotype (CK). In our cohort, the significance of biallelic status was limited to MDS with &lt;5% blasts and not for blasts 5% to 9%, as proposed by the International Consensus Classification (ICC), or 5% to 19%, as proposed by the fifth edition of the WHO (WHO-5). MDS-EB1 and -EB2 with VAF ≥10% had comparable survival (9.6 vs 7.2 months; P = .12), regardless of allelic status. Contrary to the ICC proposal, MDS-EB1/EB2 with VAF &lt;10% and CK had poor survival compared with those without CK, comparable to MDS-EB1/EB2 with VAF ≥10% (5.6 vs 26.2 vs 6.3 months; P = .003). Survival of TP53mut AML was poor (median 3.9 months) regardless of allelic/CK status. Thus, using ICC or WHO-5 may underestimate prognosis of MDS with blasts 5% to 19% and 5% to 9%, respectively. Collectively, the hierarchical model acknowledges poor survival of 91.9% TP53mut MDS and AML compared with 36.5% and 80.7% by WHO-5 and ICC, respectively.

SummaryGermline variants in DDX41 (DDX41MT‐germline predisposition syndrome [GPS]) are associated with predisposition to haematological malignancies (HM), including lymphoid and myeloid neoplasms (MN). We retrospectively analysed the clinical and molecular features of 195 patients diagnosed and treated at Mayo Clinic with DDX41MT‐GPS. Patients with germline DDX41 pathogenic variants (42.3%) and variants of unknown significance (VUS, 57.6%) were included. The median age was 68.6 years (16.2–93.4). Ninety‐two per cent were Caucasian, 64.1% were male and 30.8% had a family history of HM. There were 92 distinct germline variants among our cohort, and the most common was p.Met1? (15.9%), followed by p.Asp140Glyfs*2 (9.2%). Clinical diagnoses included asymptomatic carriers (10.2%), clonal cytopenia of undetermined significance (CCUS, 6.1%), myeloproliferative neoplasms (6.7%), myelodysplastic syndrome (40.5%), acute myeloid leukaemia (20.5%), lymphoid neoplasms (9.2%), plasma cell dyscrasias (6.1%) and solid tumours (22.5%). Patients with MN were older (median age 70 vs. 63.5 years) and more likely to be male (M:F ratio 2.3 vs. 1.0) and most patients (78.8%) with MN had a normal karyotype. The most common somatic variants involved DDX41 (34.4%), followed by TET2 (11.2%), DNMT3A (9.6%) and ASXL1 (9.2%). In summary, we have comprehensively described the spectrum of clinical phenotypes within the Mayo Clinic DDX41MT‐GPS cohort.

ABSTRACTTransplant‐associated thrombotic microangiopathy (TA‐TMA) is an endothelial dysfunction syndrome observed after allogeneic hematopoietic cell transplant (alloHCT). Our aim was to externally validate the impact of high‐risk features on the clinical outcomes of adult patients meeting the updated TA‐TMA harmonizing criteria. Between 2005 and 2022, 99 patients were diagnosed with TA‐TMA at Mayo Clinic Rochester (incidence 6.2%) after a median of 137 days post alloHCT (IQR: 34–283 days). The development of TA‐TMA was associated with an inferior overall survival posttransplant (HR: 3.8, 95% CI: 2.97–4.72). High‐risk features, including concomitant infection, acute graft‐versus‐host disease (GVHD), and organ dysfunction, were associated with poor survival, while LDH elevation was not associated with inferior outcomes. The most common treatment strategy for TA‐TMA was discontinuation of calcineurin or mTOR inhibitors in 80 (81%) patients. Thirty (37.5%) patients experienced worsening of GVHD with this strategy, of which 26 (86.7%) patients had died at last follow‐up. The most common cause of death among these patients was worsening GVHD (69%; n = 18), followed by infection (11%; n = 3), disease relapse (8%; n = 2), other/unknown causes (8%; n = 2), or TA‐TMA (4%; n = 1). Objective response rate (ORR) to initial treatment for the cohort was 56.6%. Eculizumab was used in 11 patients with an observed ORR of 70%, including 5 complete responses. In conclusion, TA‐TMA remains a significant contributor to non‐relapse mortality and is associated with worse survival following alloHCT. Not all high‐risk features, particularly LDH elevation, have consistently demonstrated a negative impact in adult cohorts. Patients with TA‐TMA may benefit from immune suppression dose adjustment, rather than a discontinuation, and the addition of complement‐directed therapy, particularly among high‐risk patients.

AbstractBackgroundSince FDA approval in 2017, CAR‐T therapy has seen rapid clinical adoption. Shifting clinical trends have emerged with increasing utilization of CAR‐T therapies and a downward trend in HSCTs. Given the overlapping resources required for the manufacture and storage of these products, we sought to examine trends over a 6‐year period.MethodsThe apheresis patient database and Lab database were reviewed to compile a list of patients that underwent either CAR‐T or HSCT (autologous) collections, and/or received CAR‐T or autologous HSCT infusions between January 1, 2018 and December 12, 2023. This was further examined by year and disease group.ResultsThe total number of patients collecting for CAR‐T increased from 52 in 2018 to 150 in 2023 (slope = 21.97; p = .0013), accompanied by a decrease in the number of patients collecting for HSCT, from 425 in 2018 to 341 in 2023 (slope = −21.2; p = .0177). Neither total number (calculated as number of HSCT + CAR‐T) of patients collected (mean 476 + 20.4 per year), nor collection procedures (mean 972 ± 75.8 per year) changed significantly over the 6‐year period. The total number of CAR‐T infusions increased from 24 in 2018 to 111 in 2023 (slope = 17.7; p = .004), with a decrease in auto‐HSCT from 400 to 289 (slope = −28.7; p = .008). The overall number of infusions (calculated as number of HSCT + CAR‐T) did not change significantly (slope = −10.9; p = .13) over the 6‐year period.DiscussionOur findings confirm the increasing adoption of CAR‐T therapy occurring alongside a decreasing stem‐cell transplants, with stable overall resource utilization.