Citations

Background Acute myeloid leukemia (AML) with TP53 mutation (m) has poor outcomes even in the contemporary era with median overall survival (OS) of 6-9 months. The only factor that has been shown to improve outcomes is allogeneic hematopoietic cell transplantation (allo-HCT) (Badar et al AJH 2022; Leukemia 2023). However, the role of allo-HCT for TP53-m AML continues to be a matter of debate given high rates of relapse after allo-HCT particularly in TP53-m AML with complex cytogenetics (CG). We used the COMMAND consortium database to investigate the factors that influenced physician's decision for allo-HCT in TP53-m AML. Method We conducted a multicenter observational study in collaboration with 7 U.S. academic centers under COMMAND consortium. We reviewed electronic medical records of 369 TP53-m AML patients to analyze reasons for not pursuing allo-HCT including refractory disease, donor availability, advanced age/co-morbidities, physician perspective on ineffectiveness of allo-HCT in improving outcome and patient's decision. Diagnostic criteria for TP53 allelic state were according to the International Consensus Classification (ICC) (Blood 2022; 140:1200). Next-generation sequencing and cytogenetic studies were performed according to institutional standard protocols. Results The median age at diagnosis was 68 years, with 222 (60.5%) patients being male. The majority of patients were diagnosed with de novo AML 179 (48.8%), followed by secondary AML (sAML) in 103 (28%) patients, and therapy-related (t)AML in 85 (23.2%) patients. Ninety-four percent of evaluable patients had complex cytogenetics (CG) and 192 (52%) had multi-hit TP53-m. One-hundred forty-seven (42%) patients received intensive chemotherapy (CPX 351 [66 (44%)], 7+3 [78 (53%)]), while 205 (58%) patients received low-intensity regimens including hypomethylating agents (HMA) plus venetoclax (137 [66%]) and HMA +/- investigational agents (68 [33%]). The rate of complete remission (CR)/CR with incomplete count recovery (CRi) was 34.4% and overall response rate (CR/CRi + partial remission [PR] + morphologic leukemia free state [MLFS]) was 52%. Forty-seven (13%) patients received allo-HCT in CR1 and 17 (5%) patients received allo-HCT in CR2. Of the 294 patients for whom data on allo-HCT decision-making was available, the most common reason for not proceeding to allo-HCT was refractory disease in 126 (43%) patients. Other significant reasons included advanced age/comorbidities (n=78 [30.6%]), physician recommendation (n=7 [2%]), patient's decision (n=24 [9.4%]), and patient relocation or changing healthcare providers (n= 9 [3.5%]). Two (0.4%) patients had no suitable donor available for allo-HCT. Amongst the 7 patients for whom allo-HCT was not pursued due to physician's decision, the median age of the patients was 69 years (R, 59-70), 3 (25%) patients had sAML, and all of them had multi-hit TP53-m associated with complex CG. Six out of seven (86%) patients received HMA plus venetoclax and 1 (14%) patient received HMA-based induction. Six patients achieved CR/CRi after induction and 1 patient had partial remission. The median survival of these patients was 11 months (R, 10.7-11.3), eventually all patients died from progressive AML. Conclusion Our survey suggests that the primary reason for not proceeding with allo-HCT was refractory disease, underlying the difficulty in achieving the disease control needed for allo-HCT. There is an urgent need for better frontline therapies tailored specifically for TP53-m AML, along with refined patient selection criteria to better identify candidates who would benefit most from allo-HCT to potentially improve their long-term outcomes.

Introduction: MPAL is a rare and heterogenous subtype of acute leukemia characterized by a single blast population with phenotypic expression of both myeloid and lymphoid lineages (biphenotypic) or multiple co-existing lineages of blasts that satisfy criteria for both acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). MPAL presents both a diagnostic and therapeutic challenge given its rarity and resistance to traditional therapies. Data suggest ALL-directed or hybrid therapies are most effective at inducing durable remissions as a bridge to allogeneic stem cell transplantation (Allo-SCT; Lazzarotto 2023, Rasekh 2021); however, many are single-institution with limited sample sizes. Methods: A retrospective analysis at 7 US academic centers was performed. Adult patients (pts) with a confirmed diagnosis of MPAL between 2003-2023 were included. Comparisons of categorical and continuous variables utilized the Fisher exact test and Wilcoxon rank-sum or Kruskal-Wallis test as appropriate. Time-to-event outcomes were calculated using the Kaplan-Meier method and compared using log-rank test. Results: A total of 79 pts with MPAL were included in this study. Median age at diagnosis was 61 years (range, 18-89); 52% were ≥ 60 years. Majority of pts were male (60%), non-Hispanic white (64%), and had an ECOG ≤ 1 (83%). Of the 50 pts with baseline CSF analysis, 5 (10%) had CNS disease. Phenotypically, the predominant blast population was biphenotypic in 68%, myeloid in 17%, and lymphoid in 15% of cases. KMT2A-rearrangement and BCR::ABL1 translocation constituted 4% and 14% of cases, respectively, and 30% of pts had complex cytogenetics. Most common mutations at baseline included RUNX1 (33%), DNMT3A (30%), FLT3-ITD (26%), TET2 (19%), WT1 (19%), NRAS (18%), TP53 (17%), and ASXL1 (14%) mutations. Of the 79 pts, 61 (77%) received intensive chemotherapy (IC), 12 (15%) received HMA-based regimens, 4 (5%) received other non-intensive regimens, and 2 (3%) transitioned to hospice prior to therapy. Among those receiving IC, 37 (61%) received ALL-directed therapies, 16 (26%) AML-directed, and 8 (13%) received hybrid regimens which included FLAG-VIPR (6/8), 7+3+vincristine (1/8), and cladrabine/low-dose cytarabine/vincristine/dexamethasone (1/8). Therapies were phenotype-discordant in 4/61 pts receiving IC; 3 myeloblast-predominant MPAL pts received ALL-directed therapy and one lymphoid-predominant pt received AML-directed therapy. Among 54 pts with predominant biphenotypic blasts, 52% received ALL-directed regimens. Of the 11 pts with BCR::ABL1 translocation, 8 (73%) received dasatinib, 2 (18%) ponatinib, and 1 (9%) received both. Only 30% of pts with FLT3-ITD mutated MPAL (5/17) received a FLT3 inhibitor. Overall, 56% of pts achieved complete remission (CR) or CR with incomplete count recovery (CRi), with a median duration of response of 16.7 months (IQR: 8.1-46.1). The rates of CR/CRi were 39%, 56%, and 75% for myeloid, biphenotypic, and lymphoid MPAL, respectively. All pts with CNS disease (5/5) cleared after induction. Thirty-seven percent of pts proceeded with Allo-SCT in first remission (23% of myeloid pts, 58% lymphoid, 35% biphenotypic). Thirty-two percent of responders (CR/CRi; 14/44) relapsed with a median time to relapse of 9.4 months (range, 0.5-42). Median overall survival (OS) for the entire cohort was 51 months (95% CI: 15-89). The 2-year OS rate was higher in pts with lymphoid-predominant phenotype (83%) compared to biphenotypic (55%) or myeloid-predominant phenotype (38%; p=0.16). Median OS was significantly longer in transplant versus non-SCT recipients (121 vs 14 months) with a 1-year OS rate of 97% vs. 59% (p<0.0001), respectively. Among pts who achieved CR/CRi, median OS significantly longer in transplant versus non-SCT recipients (121 vs 55 months, p=0.031), with a 2-year OS rate of 91% vs 75%. Conclusions In this large multi-center study, there were differences in survival based on predominant blast phenotype, with improved OS in lymphoid-predominant MPAL. Although most pts with biphenotypic-predominant MPAL received ALL-directed regimens, OS was worse in this subtype compared to lymphoid-predominant MPAL. There was significantly improved OS among Allo-SCT recipients underscoring the importance of Allo-SCT in this subtype of acute leukemia. Additional studies are needed to understand this rare and heterogenous disease.

Introduction: VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is an adult-onset autoinflammatory disorder defined by somatic UBA1 mutations in hematopoietic cells. VEXAS is associated with a high frequency of clonal hematopoiesis (CH- 60%); with the clonal landscape being dominated by DNMT3A mutations. In our prior study (Gutierrez-Rodrigues Blood 2023), we showed that DNMT3A mutations in VEXAS associated with increased mortality, but without a higher risk of MDS/AML. As DNMT3A is a critical epigenetic regulator, we conducted this study to define the epigenetic deregulation and impact on mortality of DNMT3Amt (mutant) CH in VEXAS. Methods: After IRB approval, 88 VEXAS patients from the Mayo Clinic and the NIH were retrospectively assessed, including 81 screened for CH by error-corrected DNA sequencing (ECS). DNA methylation changes were identified using the Illumina Infinium MethylationEPIC BeadChip on peripheral blood samples (PB). Cellular indexing of transcriptomes and epitopes (CITE)-seq was performed using the 10x Chromium 3' GEX platform; 16,600 pooled cells were subjected to UMAP dimensionality reduction, followed by Azimuth based cell identification. Genotyping of targeted loci with chromatin accessibility (GoTChA) was conducted on two PB DNMT3Amt samples from CCUS individuals (Izzo et al Nature 2024). Results: Patients' median age was 70 years (range: 56 - 89); 95% were white. Twelve out of 81 patients screened by ECS were found with a DNMT3Amt (15%), with a median variant allele fraction (VAF) of 42% (range: 6-46%). In this cohort, while the presence of any CH mutation did not impact survival, DNMT3Amt CH had an age-independent negative impact on mortality (5.5 years vs 8.7 years, p =0.005), without an increase in risk for MDS/AML. Changes in DNA methylation were profiled in 19 and 9 VEXAS patients without CH (Median Age: 68) or with DNMT3Amt CH (Median Age: 74), respectively. VEXAS samples with DNMT3Amt CH had >4,000 differentially methylated CpGs with 95% of the CpGs being hypomethylated compared to those without CH. Using the Roadmap Epigenomics project, we found that this hypomethylation was enriched at enhancer (Enh) sites and actively transcribed states (TxWk). Pathway analysis revealed that the hypomethylated sites were in or near genes involved in the development and differentiation of leukocytes, with IL-13 and IL-15 being identified as upstream regulators of the methylation changes. Bulk RNA-seq performed on PB of 2 and 3 VEXAS patients with and without DNMT3Amt, respectively, identified >1,500 differentially expressed genes in DNMT3Amt samples, 78% of these being overexpressed. Pathway analysis was enriched in gene pathways involved in the development of leukocytes, with IL-13 and IL-15 once again being identified as upstream regulators. Integration of methylation and transcriptomic data identified upregulation of several genes within the IL-13 and IL-15 pathways, with these regions correlating with a decrease in methylation. To assess if the epigenetic dysregulation is linked to DNMT3A mutations, we performed GoTChA-seq on two DNMT3Amt clonal cytopenia samples (CCUS). The comparison of the number of cutsites in DNMT3A wild type vs mt cells from the same individual demonstrated increased open chromatin within the IL-13 and IL-15 pathways in mt cells, both globally and in a genomic locus specific manner. CITE-seq performed on 3 VEXAS samples (2 DNMT3Amt CH vs 1 no CH) further showed that expression of genes involved in IL-13 and IL-15 pathway is significantly increased in CD4+ and CD8+ T cells from DNMT3Amt samples, suggesting a paracrine regulatory effect of T lymphocytes (mostly UBA1 and DNMT3A wild-type) in VEXAS. Pathway analysis of DEGs in these cells also revealed an enrichment of genes involved in inflammation and lymphocyte proliferation. Conclusions: Our study validates the age-independent, negative prognostic impact of DNMT3Amt CH on survival in VEXAS syndrome. DNMT3Amt mediates epigenetic and transcriptional priming associated with upregulation of IL-13/15 pathway in CD4/CD8 T cells, which are mostly DNMT3A and UBA1 wild-type, suggesting that the contribution of T lymphocytes to inflammation may be secondary to CH in the myeloid compartment.

Severe COVID-19 is a multisystem condition with thromboinflammation as a significant driver of morbidity and mortality. Cellular components involved in inflammatory and coagulation responses include platelets, endothelium, monocytes, and neutrophils. Thrombotic manifestations, such as arterial thrombosis, venous thromboembolism, and tissue microthrombosis, occur in at least 20% of ICU COVID-19 patients, possibly more based on postmortem studies. This study investigates the presence of prothrombotic antibodies similar to those found in heparin-induced thrombocytopenia (HIT), a condition caused by platelet-activating antibodies targeting platelet factor 4 (PF4) when complexed with heparin (PF4/H). In a study of samples from 130 hospitalized patients collected on average 3.6 days after COVID-19 diagnosis, 80% were found to have IgG antibodies recognizing PF4/H. This percentage is significantly lower than in 22 HIT patients (100%) but higher than in 51 non-COVID-19 patients with acute respiratory symptoms (ARS) (25%) and 12 healthy subjects (0%). Additionally, 41% of the 130 patients had antibodies inducing PF4-dependent P-selectin expression in CpG-treated normal platelets, a rate significantly lower than in 12 HIT patients (100%) but higher than in 51 non-COVID-19 ARS patients (20%) and 12 healthy subjects (0%). Significantly, platelet-activating antibodies in COVID-19 patients were associated with a specific elevation of platelet α-granule proteins in the plasma and correlated with inflammation and tissue damage markers, suggesting these antibodies' functionality in patients. Significantly, unlike HIT, both PF4/H-reactive and platelet-activating antibodies were found in COVID-19 patients regardless of recent heparin exposure, indicating different antigenic stimuli for these antibodies in COVID-19. Notably, certain antibodies against the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 possessed sequence motifs, RKH and Y5, in the heavy-chain complementarity-determining region 3 (HCDR3) resembling those in pathogenic HIT antibodies identified in our previous studies, suggesting that these antibodies can activate platelets. Introducing exogenous RBD to COVID-19 plasma or IgG purified from COVID-19 plasma significantly reduced their ability to activate platelets. Furthermore, immunodepleting RBD-reactive antibodies from COVID-19 plasma or IgG purified from COVID-19 plasma using RBD-coated beads significantly reduced their ability to activate platelets. These findings demonstrate that some RBD-specific plasma IgG antibodies can activate platelets. To demonstrate the presence of RBD-specific, platelet-activating antibodies at the clonal level, we produced recombinant antibodies from 42 RBD-binding IgG+ B cells, tested their ability to activate platelets, and identified four that could do so. Interestingly, three antibodies possess HCDR3 sequences resembling RKH or Y5 motifs. Additionally, we identified RKH or Y5 motifs in RBD-specific antibodies reported by other groups, produced 15 such antibodies recombinantly, tested their ability to activate platelets, and identified four more that could do so. IgG+ B cells with these HCDR3 motifs were markedly expanded in severe COVID-19 patients, suggesting an expansion of B cells producing platelet-activating antibodies. The demonstration of functional and structural similarities between certain RBD-specific antibodies in COVID-19 patients and pathogenic HIT antibodies suggests a novel mechanism by which RBD-specific antibodies might contribute to thrombosis in COVID-19.

Introduction: TP53 mutations are found in 18% of adult patients (pts) with acute lymphoblastic leukemias (ALL), and portends poor prognosis (Saygin, Blood Cancer Discov 2024). TP53 mutations are often associated with low hypodiploidy and Li Fraumeni syndrome (germline) in children. However, we and others have shown that TP53-mutant (TP53-m) ALL arises from pre-existing TP53-m clonal hematopoiesis in adults as opposed to germline origin. The impact of co-occurring mutations, TP53 allelic frequency (AF) and different types of treatment on outcomes of TP53-m ALL are not fully characterized. We set out to investigate the clinical and molecular predictors of outcomes in adults with TP53-mutant ALL. Methods: We retrospectively studied 107 patients with TP53-m ALL treated at seven different academic centers in North America. Genetic profiling of pre-treatment bone marrow samples was performed with a comprehensive panel covering 147 myeloid and lymphoid genes. We also performed RNA-sequencing to identify fusions that define ALL subtypes. Single nucleotide polymorphism (SNP) array was used to define low hypodiploidy. Results: The median age at diagnosis was 59 years (range, 10-80), 42% were female, 70% White. 89% of pts had B-ALL while 11% had T-lineage ALL. 24% of pts were classified to have therapy-related ALL based on their history of exposure to genotoxic therapy for another cancer. 45% of pts had hypodiploid karyotype, 79% of whom were low-hypodiploid. 7% had hyperdiploid karyotype and 5% had BCR::ABL1. 11 pts had two different TP53 variants. 90% of TP53 variants involved the DNA binding domain. Most frequently observed co-occurring mutations involved CDKN2A (20%), NOTCH1 (12%) and RB1 (10%) genes. 71% of pts were treated with standard cytotoxic chemotherapy, while the remaining pts received newer antibody-based therapies (i.e., inotuzumab, blinatumomab) or venetoclax in first-line setting. 11% of pts received allogeneic hematopoietic cell transplant (HCT) in first complete remission (CR1) while 3% received HCT after relapse (CR2 or CR3). When patients with vs without low hypodiploidy were compared, we did not observe a significant difference in overall survival (OS) as outcomes were poor in both groups (median, 17 vs 19 months, p= 0.89). However, pts who had TP53 AF >0.5 had significantly worse OS when compared to pts with TP53 VAF <0.5 (13 vs 25 months, p= 0.03). Conclusions: TP53-m ALL is a very high-risk disease subtype and its dismal outcome is independent from presence of co-existing low hypodiploidy. Loss of heterozygosity, characterized by TP53 AF >0.5 is associated with even worse survival. New therapies are urgently needed to improve outcomes in this subset.

Background: Fc receptor-homolog 5 (FcRH5) is a type I membrane protein that is expressed exclusively in the B-cell lineage, and at a higher level on multiple myeloma (MM) cells than on normal B cells. Cevostamab is a FcRH5xCD3 bispecific antibody that facilitates T cell-mediated killing of MM cells. In an ongoing Phase I dose-escalation and dose-expansion study (GO39775; NCT03275103), cevostamab monotherapy demonstrated target dose (TD)-dependent activity and manageable safety in patients (pts) with heavily pretreated RRMM (Trudel et al. ASH 2021). We report updated efficacy and safety data from pts who received cevostamab once every 3 weeks (Q3W) at the 160mg TD level. Methods: Eligible pts were those with RRMM for which no established therapy was available or appropriate. Cevostamab was initiated with Cycle (C) 1 single-step (SS) dosing, double-step (DS) dosing (Trudel et al. ASH 2021), or triple-step (TS) dosing (step doses on D1, D2 [or D3 or D4 depending on the emergence and resolution of cytokine release syndrome [CRS] with the previous administration], and D8, TD on D9 [or D10 or D11]). Cevostamab was then continued at the TD on D1 of each subsequent 21-day cycle. Cevostamab was continued for 17 cycles, unless disease progression or unacceptable toxicity occurred. Results: As of February 23, 2024, 167 pts (median age: 66 years, range: 40-90; ECOG PS: 0, 35% or 1, 65%; median time from first MM therapy: 6.3 years, range: 0.3-21.8) had received cevostamab at the 160mg TD level (SS: n=10; DS: n=97; TS: n=60); 28% of pts had extramedullary disease and 38% of pts with a conclusive assay result (38/100) had high-risk cytogenetics (t(4;14), t(14;16), or del(17p)). The median number of prior lines of therapy was 6 (range: 2-18). Almost all pts (95.8%) were triple-class refractory and 73.7% were penta-drug refractory; 85.0% were refractory to their last prior therapy. A majority (57%) of pts had received ≥1 prior B-cell maturation antigen (BCMA)-targeted therapy. Twenty four percent of pts had received ≥1 prior bispecific antibody. Median observation time was 11.3 months (range: 0.5-42.8). The overall response rate (ORR) in all pts who received cevostamab at the 160mg TD level was 43.1% (72/167 pts); 6.6% achieved a stringent complete response (CR), 6.6% a CR, 12.6% a very good partial response (VGPR), and 17.4% a partial response (PR). The VGPR or better rate was 25.7%. Median time to first response (PR or better) was 1.4 months (range: 0.6-4.6) and to best response was 2.4 months (range: 0.7-13.4). Median duration of response was 10.4 months (95% CI: 6.8, 10.5). ORR was 30.2% (29/96) in pts with ≥1 prior BCMA-targeted therapy and 60.6% (43/71) in those without. ORR was 30.0% (12/40) in pts with ≥1 prior bispecific antibody, 33.3% (20/60) with ≥1 prior chimeric antigen receptor (CAR) T-cell, and 41.2% (14/34) with ≥1 prior antibody-drug conjugate. Common (≥20%) adverse events (AEs) included CRS (74.3%; Grade [Gr] 1: 52.7%; Gr 2: 19.8%; Gr 3: 1.2%; Gr 4: 0.6%), neutropenia (31.1%; Gr 1-2: 3.0%; Gr 3: 12.0%; Gr 4: 16.2%), cough (30.5%; Gr 1-2: 29.9%; Gr 3: 0.6%), nausea (28.1%; Gr 1-2: 27.5%; Gr 3: 0.6%), diarrhea (24.0%; all Gr 1-2), anemia (23.4%; Gr 1-2: 5.4%; Gr 3: 17.4%; Gr 4: 0.6%), and fatigue (21.0%; Gr 1-2: 19.8%; Gr 3: 1.2%). Possible immune effector cell-associated neurotoxicity syndrome (ICANS) occurred in 13.2% of pts (Gr 1: 6.0%; Gr 2: 5.4%; Gr 3: 1.8%). Infections occurred in 53.9% of pts, with serious events and Gr ≥3 events in 22.2% and 19.2%, respectively. Treatment-related AEs leading to cevostamab discontinuation occurred in 11 pts (6.6%) and treatment-related Gr 5 (fatal) AEs in 3 pts (1.8%; hemophagocytic lymphohistiocytosis, n=2; disseminated intravascular coagulation and pseudomonal sepsis, n=1). In the 0.3/1.2/3.6/160mg TS cohort, CRS occurred in 19/30 pts (63.3%) and was all Gr 1 (46.7%) or Gr 2 (16.7%). Pts with CRS were managed with tocilizumab (47.4%), steroids (21.1%), or both agents (10.5%). No pts discontinued cevostamab due to CRS and all events were resolved at cut-off. Conclusions: Cevostamab demonstrates clinically meaningful activity and manageable safety at the 160mg TD level in pts with heavily pretreated RRMM. C1 TS dosing provides effective CRS mitigation. Cevostamab combination studies may use the 0.3/1.2/3.6mg TS regimen and the Q3W 160mg TD (or similar TD exposure).

Background: CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy is an established treatment with high efficacy in treating relapsed or refractory (R/R) mantle cell lymphoma (MCL). However, with CAR-T therapy, refractory disease occurs and a continuous pattern of relapse over time has been observed. Limited data exist about post-CAR-T progression of disease (POD) management and outcomes in MCL. Such data would meaningfully inform practice and set a critical benchmark for future studies in the post-CAR-T setting. We characterized treatment patterns and outcomes for pts with POD after CD19 CAR-T therapy for R/R MCL. Methods: We queried institutional databases to identify pts with R/R MCL who received CD19-directed CAR-T therapy. Treatment may have occurred as standard-of-care or in a clinical trial. We performed chart review to extract variables and categorized therapies by mechanism(s) of action. We used descriptive statistics to characterize patient/disease characteristics and treatment patterns, the reverse Kaplan-Meier method to calculate follow-up, the Kaplan-Meier method to calculate survival, and Cox proportional hazards to associate clinical and disease features with survival outcomes. Results: Across 9 sites, we identified 306 pts who received CD19 CAR-T for R/R MCL, of which 104 (34%) experienced POD and were investigated in detail: pts with POD were mostly men (73%), had a median age of 67 yrs (range 36-86) at infusion, and had received a median of 3 lines of therapy pre-leukapheresis, including a BTK inhibitor (BTKi) in 97% of patients; 36% of BTKi-exposed patients had BTKi-unresponsive disease. High-risk tumor features were common pre-CAR-T: 47/68 (69%) with a TP53 mutation, 66/93 (71%) with Ki67 ≥50%, and 47/102 (46%) with blastoid/pleomorphic MCL. Most pts (75%) received bridging therapy. Pts received brexucabtagene autoleucel (88%) or lisocabtagene maraleucel (12%). Regarding best CAR-T response for pts with POD, 71% had a complete response (CR), 13% partial response (PR), and 15% had no response. The median time from CAR-T infusion to POD was 6 months (IQR 3-12). At time of POD, high-risk MCL features were again common: 55% blastoid/pleomorphic, 42/56 (75%) Ki67 ≥50%, 51/83 (61%) MIPIb high-risk, and 21/35 (60%) TP53-mutated MCL. Among 69 pts with CD19 assessed on a post-POD biopsy, 8 (12%) had CD19-negative disease. 30% of pts had an ECOG performance status of ≥2 at time of POD. After POD occurred, 15 pts received no anti-lymphoma therapy (Tx), 11 pts underwent excision or radiation, and 78 pts received systemic therapy. The most commonly used first-line systemic Tx post-CAR-T progression included: pirtobrutinib in 13 pts [overall response rate (ORR) 31%], chemoimmunotherapy in 12 pts (ORR 25%), venetoclax in 10 patients (ORR 20%), bispecific antibodies (BsAb) in 10 pts (ORR 60%), and small molecule combinations (at least 2 of BTK inhibitor, BCL2 inhibitor, and lenalidomide) in 8 patients with ORR 50%. The ORR to all first systemic Tx post-POD was 42%. The median follow-up from POD is 15.2 months among survivors. The median progression-free and overall survival (OS) from time of POD were 2.3 (95% CI 1.9-3.4) and 5.4 months (95% CI 4.5-9.4), respectively, and 1-year OS rate was 33%. TP53 mutations predicted inferior OS (HR 2.83, 95% CI 1.08-7.43, P = 0.026) as did age ≥65 years at time of POD (HR 1.83, 95% CI 1.07-3.15, P = 0.023), MIPIb high-risk (HR 3.56, 95% CI 1.08-11.7, P = 0.042), and non-response to CAR-T (HR 3.55, 95% CI 1.93-6.53, P < 0.001). Discussion: Our data, the largest reported cohort of pts with POD post-CAR-T with R/R MCL, confirm the poor prognosis in this patient population, with a median OS of 5.4 months. BsAbs showed promise with an overall response rate of 60%. The presence of a TP53 mutation significantly predicted inferior OS, corroborating the prognostic importance of this finding in the post-CAR-T context. Data from pts treated at additional sites and updated analyses will be presented at the meeting.

Background: The majority of patients respond to steroid treatment for graft-vs-host disease (GVHD), but the typically high doses and prolonged courses can cause substantial morbidity. GVHD can be classified at onset into two groups with significant differences in treatment response and non-relapse mortality (NRM) by clinical criteria (Minnesota risk) but the more favorable standard risk group still experiences high rates of treatment failure and NRM [MacMillan, BBMT 2015]. We previously validated a serum biomarker-based (ST2+REG3α) risk stratification system, MAGIC algorithm probabilities (MAPs), that can stratify patients both at initiation and during treatment into risk groups for treatment response and NRM [Hartwell, JCI Insight 2017, Srinagesh, Blood Adv 2019]. GVHD that is Minnesota standard risk and has a low MAP (i.e., Ann Arbor 1) at start of treatment represents a low risk group with >80% response rate to steroids and ~10% NRM [Etra, Blood 2023]. We hypothesized that serial monitoring of GVHD symptom severity and MAPs twice (days (d) 7 and 14) in patients with clinical and biomarker defined low risk GVHD could further stratify patients into clinically meaningful groups. Methods: We retrospectively determined MAPs at d7 and 14 in 450 patients with low risk GVHD who participated in a prospective, multi-center, observational trial and were treated with systemic steroids between 2015-2023. MAPs <0.291 at days 7 and 14 were defined as low risk based on a previously validated threshold [Major-Monfried Blood 2018]. Clinical responses were scored as complete (CR), partial (PR), or non-response (NR) by standard criteria. Initiation of second line therapy was considered NR. Patients were categorized into three groups (A-C) based on clinical responses and MAPs at days d7 and 14. A: CR/PR by d14 and low MAP at both d7+14; B: stable or worse GVHD (NR) by d14 with low MAP at both d7 and 14; C: any response with a high MAP at d7 or 14. The endpoints were clinical response at day 28 (overall response rate, ORR=CR or PR), regardless of earlier response status, and 6-month NRM. Results: The median age of the study population was 54 years (range: 0-79); 19% of patients received PT-Cy for GVHD prophylaxis. Target organ involvement was skin ± upper GI (66%), lower GI (23%), isolated UGI (11%), and skin+liver (1%), and GVHD severity was grade I (35%), II (61%), and III (4%) at start of treatment. Patients in group A (n=310, 69%), clinical responders with low MAPs through day 14, had excellent d28 ORR (93%) and very low NRM (4%). GVHD in this group was considered ultra-low risk (ULR) and subset analyses revealed highly consistent d28 ORR and NRM, regardless of target organ severity, age (<18, 18-59, >60), HCT-CI score, conditioning intensity, and GVHD prophylaxis. Group B patients comprised clinical non-responders with low MAPs through day 14 (n=112, 25%); half of them responded by d28 and their NRM was low (8%), albeit double that of group A (p=0.079). Group C was small (n=28, 6%) and included both clinical responders (n=20, 4%) and clinical non-responders (n=8, 2%) who had at least one high MAP through day 14. Their d28 ORR was 54% but NRM increased four-fold (32%) and was significantly worse than patients who maintained low MAPs regardless of clinical response (p<0.001). Conclusion: Serial monitoring by clinical response and biomarkers during the first two weeks of treatment identifies a small number of high risk patients whose GVHD is initially low risk (group C). This group experiences high NRM regardless of clinical response to steroid treatment and may benefit from treatment escalation. Patients with low risk GVHD who do not have an early clinical response to steroids but maintain low MAPs, (group B) have reasonably good long-term outcomes with standard treatment. Finally, serial monitoring identifies a very large subset of patients with ULR GVHD (group A) who respond exceptionally well to standard treatment and experience very low rates of 6-month NRM regardless of pre-transplant characteristics and GVHD prophylaxis. Such patients may benefit from treatment de-escalation strategies such as shorter courses of lower dose steroids, a strategy we are currently testing in a clinical trial (NCT05090384).

Background Endpoints for GVHD treatment trials use early response (i.e, day (D)28 of treatment) as a surrogate for long term survival. Overall response (OR) that combines complete (CR) and partial responses (PR) at day (D) 28 is the conventional endpoint for primary acute GVHD trials because of similar survival outcomes between CR and PR. D28 OR ignores symptom severity at baseline and D28, however, and the PR category encompasses a wide range of responses from minimal improvement to near complete resolution of symptoms. D28 OR is the only endpoint currently approved by the FDA for efficacy, but it has not been re-evaluated as an endpoint for primary treatment (1L) in fifteen years and little is known regarding the prognostic value of D28 OR as an endpoint for second line treatment (2L) of GVHD. We hypothesized that refinement of the current D28 OR criteria, particularly through recategorization of PR in the GI tract, the main driver of nonrelapse mortality (NRM), would more accurately reflect disease control and better predict survival outcomes than current D28 response. Methods The Japanese Society for Transplantation and Cellular Therapy (JSTCT) collaborated with the Mount Sinai Acute GVHD International Consortium (MAGIC) to develop and validate D28 refined response (RR) criteria for 1L and 2L treatment (tx) in patients with Grades II-IV acute GVHD. To maximize the correlation between treatment success (i.e, response) with long term survival, our primary measured metric was the negative predictive value (NPV). We first randomly divided the 1L tx cohort of JSTCT into the training (n=2341) and validation sets (n=1156). In the training set we used a classification and regression tree (CART) algorithm to generate RR criteria that predicted 6-month (mo) NRM based on symptoms both at tx onset and D28. We then compared the two D28 response endpoints (RR vs OR) as surrogates for 6-mo NRM in two validation sets of both 1L tx (JSTCT: n=1156; MAGIC: n=1141) and 2L tx (JSTCT: n=510; MAGIC: n=196). Results The CART algorithm defined a RR as GVHD Grades 0/I at D28 without additional tx; all other D28 grades were considered refined nonresponses. As expected, RR successfully stratified the risk of 6-mo NRM in both 1L tx validation sets (JSTCT: 8% vs 38%, p<0.01; MAGIC: 9% vs 37%, p<0.01). We defined a discordant nonresponse as a nonresponse by RR criteria but a response by OR criteria, which accounted for the majority (~75%) of differences between RR and OR. 6-mo NRM in discordant nonresponders was four fold higher than in responders (JSTCT: 35%; MAGIC: 30%). The large majority (>80%) of discordant nonresponders had persistent GI GVHD at D28. Because the proportion of discordant nonresponders was small (<7% of the total population) in the 1L setting, the improvements of an already high NPV were small (JSTCT: 93% vs 91%; MAGIC: 91% vs 90%). In the 2L tx validation sets, RR also stratified the risk of 6-mo NRM (JSTCT: 26% vs 56%, p<0.01; MAGIC: 13% vs 55%, p<0.01). At the time of 2L tx, the discordant nonresponders are more common and half of the discordant nonresponders experienced 6-mo NRM (JSTCT: 45%; MAGIC: 59%); as a result, RR achieved much higher NPVs than OR (JSTCT: 75% vs 66%; MAGIC: 87% vs 76%). Deaths in responders from acute GVHD (vs. other causes such as infection) were more frequent in OR than RR in both 2L tx validation sets (JSTCT: 41% vs 20%; MAGIC: 41% vs 13%) and 1L tx validation sets (JSTCT: 25% vs 18%; MAGIC: 32% vs 29%). D28 RR is superior to OR because it more accurately reflects control of serious GVHD in four independent validation cohorts, particularly in patients with GI disease. Conclusion We conclude that RR is a more accurate endpoint than OR in patients with grade II-IV GVHD primarily because it classifies persistent GI GVHD at D28 as a non-response instead of a response, which correlates with 6-mo NRM and achieves a higher NPV. This validated RR metric can serve as a better endpoint than OR in assessing treatment efficacy in both primary treatment trials that enrich for high risk GVHD, e.g. GI involvement, and second line treatment trials.

Introduction Poor diet quality, elevated body mass index (BMI), insulin resistance, microbiome dysbiosis, inflammation as well as immune dysfunction have all been implicated in progression from monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) to multiple myeloma (MM). Plant-based diets have been associated with reduced risk of MGUS and MM in epidemiological studies. Whether a dietary intervention can impact these modifiable risk factors and delay disease progression has not been investigated. Methods We conducted a pilot, single-arm trial providing controlled high fiber plant based dietary (HFPBD) intervention for 12 weeks and health coaching for 24 weeks in 20 patients with MGUS/SMM with BMI≥25 (NCT04920084). The primary endpoint was feasibility (adherence and BMI reduction). Secondary and exploratory endpoints included quality of life, metabolic markers (insulin, adiponectin, leptin, LDL cholesterol), microbiome (diversity and composition by 16S and shotgun sequencing) and immune profiling in peripheral blood (flow cytometry and Olink inflammation panel) and bone marrow (scRNAseq and ATACseq). We also conducted an in vivo study in transgenic Vk*MYC mice fed a high fiber or control diet at the phase of mouse(m)SMM. The mice were monitored for the progression to active mMM. Differences in microbiome and immune response profiles between high fiber- and control-treated mice were assessed via microbiome 16S sequencing and flow cytometry. Results The HFPBD intervention was safe, feasible, improved quality of life and addressed modifiable risk factors - metabolic profile (improved BMI, insulin resistance, adiponectin leptin ratio), microbiome profile (increased alpha-diversity and butyrate producers) and immune (decreased inflammation and increased anti-inflammatory classical monocyte) subsets. A reduction in long-term progression trajectory was observed in 2 patients. Consistently, the high fiber diet delayed progression from mSMM to mMM in Vk*MYC mice increasing median progression-free survival from 12 weeks in the control arm to 30 weeks in the high fiber diet intervention arm. Additionally, in the intervention arm 40% of mice did not progress to mMM during the study period whereas all mice in the control arm progressed. Both human and mouse data showed that HFPBD modulated gut microbiota composition favoring the expansion of butyrate-producing bacteria. Additionally, short-chain fatty acids were increased in the feces of mice fed a high fiber diet. Integrated analysis from human bone marrow and peripheral blood analysis indicated that the dietary intervention reduced inflammatory biomarkers and skewed the immune response towards T helper and CD14+ monocytes. Consistently, the bone marrow of Vk*MYC mice fed high fiber diet was more infiltrated by IFNg-producing T lymphocytes while displaying less exhausted T cells and immunosuppressive myeloid cells. Conclusion This is the first interventional clinical trial and in vivo study to show that a HFPBD intervention may delay progression from MGUS/SMM to MM. To our knowledge there has been no similar dietary interventional study in hematological cancers or solid tumors. Together our in vivo and clinical data support the beneficial anti-inflammatory role of a HFPBD providing a link between diet, microbiota, and immune modulation to delay disease progression in MGUS/SMM.