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Introduction: Based on a donor versus no-donor analysis, UKALLXII/E2993 showed a survival benefit for adults with acute lymphoblastic leukemia (ALL) who underwent allogeneic hematopoietic cell transplantation (alloHCT) in first complete remission (CR1) compared to consolidation/maintenance chemotherapy alone. The follow-up phase 3 E1910 trial (NCT02003222) randomized BCR::ABL1-negative B-lineage ALL patients (pts) aged 30-70 years in measurable residual disease (MRD)-negative CR1 after intensification to conventional chemotherapy (CC) +/- blinatumomab (blin) and demonstrated significantly improved overall survival (OS) with blin (Litzow, NEJM 2024). The current exploratory subgroup analysis evaluates outcomes of MRD-negative pts randomized on E1910 who underwent alloHCT on trial. Methods: Among pts enrolled on E1910, pts in MRD-negative CR1 by 6-color flow cytometry after intensification who were randomized to CC +/- blin and subsequently underwent alloHCT were identified. We compared baseline characteristics, MRD status post induction, relapse-free survival (RFS) and OS using the Kaplan-Meier method and the two-sided log-rank test and Cox model. A multivariable analysis was performed with alloHCT included as a time-varying covariate as well as a landmark analysis comparing the outcome of pts with unfavorable risk on the CC + blin arm who underwent alloHCT versus those who did not. Results: Of 224 MRD-negative randomized pts, 44 underwent alloHCT on trial: 22 in each arm. The median time from randomization to transplant was 3.2 months (mos). The median follow-up from initial registration was 57.8 mos. Baseline demographics including age (median 55 years), gender (53% male), race (89% white) and ethnicity (89% non-Hispanic/Latino) were equally distributed. Compared to CC + blin, the median peripheral blood white cell (WBC) count and blast percentage at diagnosis were higher in the CC arm at 6,640 vs 3,740/uL and 55 vs 9%, respectively, while median marrow blast percentage and overall unfavorable risk as defined in E1910 (55% vs 64%) were similar. Of the 44 MRD-negative pts who proceeded to alloHCT on study, 77% in the CC arm and 64% in the CC+ blin arm were MRD-negative after induction. Myeloablative conditioning was given to the majority of pts (68% CC arm and 73% CC+blin arm) and the most common graft versus host disease prophylaxis was tacrolimus-based on both arms. Among the 44 pts who underwent alloHCT, the observed hazard ratio (HR) comparing relative risk of death between pts randomized to CC+blin or CC only was 0.59 (95% CI: 0.12-2.11) with a 3-year OS rate of 82% versus 71% and the HR comparing relative risk of relapse/death was 0.52 (CI: 0.15-1.79) with a 3-year RFS rate of 82% versus 67%. For patients with unfavorable risk, 3-year OS and 3-year RFS in each treatment arm were both 71% versus 65%. Among 50 pts with unfavorable risk in MRD-negative CR after intensification who were randomized to CC + blin, a landmark analysis performed at 5 mos post randomization showed 3-year OS and RFS rates of 71% versus 90% and 71% versus 86% between the 14 pts who underwent alloHCT and those who did not, respectively. Receipt of alloHCT was a time-varying covariate in a multivariable analysis with gender, WBC count, platelets, hemoglobin, peripheral blood blasts, bone marrow blasts, performance status, and combined molecular risk category. Age, CD20 status, rituximab use, and intention to receive alloHCT were used as stratification factors. In the entire cohort of MRD-negative pts who were randomized, there was a significant association between improved OS and the receipt of CC+blin vs CC alone (HR 0.46, 95% CI: 0.26 - 0.82; p=0.009), better performance status of 0-1 vs ≥2 and favorable vs unfavorable risk ALL. In contrast, the receipt of alloHCT had no significant effect on OS (HR 1.00, 95% CI: 0.49 - 2.01). Conclusions: Within the constraints of small numbers, this exploratory subgroup analysis demonstrates that in pts with newly diagnosed BCR::ABL1-negative B-ALL treated on E1910 who achieved MRD-negativity after intensification, alloHCT outcomes did not appear to be different with or without blin in consolidation. In a multivariate analysis of all MRD-negative pts, receipt of blin but not alloHCT was associated with improved OS. Further investigation is warranted to characterize the relative benefit of blinatumomab in pts receiving alloHCT in frontline consolidation.

Introduction: The optimal induction for younger fit patients (pts) with mantle cell lymphoma (MCL) is unknown; though intensive chemoimmunotherapy (CIT) containing high dose cytarabine has been shown to prolong remission. Achieving molecular remission is an independent predictor of outcomes post induction therapy in patients with MCL. Incorporating undetectable measurable residual disease (uMRD) status into the primary endpoint may be preferable to progression-free survival (PFS), particularly when approaches following induction are varied (e.g., ASCT, maintenance treatment, observation). Induction with 3 cycles of bendamustine and rituximab followed by 3 cycles of cytarabine and rituximab (BR/CR) is associated with high complete metabolic response (CMR) and uMRD rates (Armand et al., BJH 2016; Merryman et al., Blood Adv 2020). Bruton's tyrosine kinase inhibitors (BTKi) including ibrutinib and acalabrutinib (A) in combination with CIT are highly effective in MCL (Wang et al., EHA 2024, LBA 3439). In 2019, the US Intergroup activated EA4181 to explore the efficacy with the addition of fixed duration BTKi, to BR or BR/CR for patients with MCL ≤ 70 years old. Patients and methods: Patients were randomized 1:1:1 (stratified by MIPI risk status) to 6 cycles of BR/CR (control arm), BR/CR-A, or BR-A. Cytarabine was dosed at 2 g/m2 Q12 hours x 4, with dose reductions based on age and creatinine clearance. Acalabrutinib was dosed at 100 mg BID continuously on BR cycles with the BR/CR-A and BR-A arms and at 100 mg BID on days 1-7 and 22-28 with CR cycles on the BR/CR-A arm to mitigate hematologic toxicity. Consolidation approaches following induction were at the discretion of the treating physician. The primary endpoint was a composite of PET/CT CMR and peripheral blood uMRD rate (< 1 in 105). ClonoSEQ (Adaptive Biotechnologies) was performed at baseline and MRD testing was obtained at the end of induction. Secondary clinical objectives included PFS and overall survival (OS) at 36 months (mo), objective response rates (ORR), and toxicity rates. With 108 patients per arm expected, there was 86% power to detect an increase in PET/CT CMR/uMRD rate from 60% in the control arm to 75% in either BR/CR-A or BR-A arms using a Z-test with a 10% alpha (1-sided). Results: Between October 2019 and March 2023, 359 participants were randomized to BR/CR (n = 128), BR/CR-A (n = 129), and BR-A (n = 102). BR-A was closed to further accrual by the DSMC based on interim futility analysis for superiority in Fall 2022. The median (range) age was 61 (25, 70), 30% were ≥ 65 years, 77% were male, 89% were white, 89% were non-Hispanic, 18%/43%/39% were low/intermediate/high risk MIPI. Baseline clonal sequence was identified in 308/326 (95%) among samples received. 281/308 were eligible and treated and 260/281 had an end of treatment MRD test result (BR/CR = 85, BR/CR-A = 98, BR-A = 77). This subset (n = 260) is the focus of the primary analysis; sensitivity analysis included 281 eligible and treated pts with trackable clonal marker. In the primary analysis subset, 94%, 91%, and 90% in BR/CR, BR/CR-A, and BR-A arms, respectively, completed 6 cycles of protocol therapy. The PET/CT CMR/uMRD rates were 82% (BR/CR), 82% (BR/CR-A; p = 0.55 vs BR/CR), and 78% (BR-A; p = 0.76 vs BR/CR). In the sensitivity analysis set, PET/CT CMR/uMRD rates were 74% with BR/CR (n = 94), 76% (p = 0.44) with BR/CR-A (n = 106), and 74% (p = 0.52) with BR-A (n = 81). ORR (CMR) rates were 94% (91%), 99% (90%), and 94% (91%) with BR/CR, BR/CR-A, and BR-A, respectively. At a median follow-up of 27.9 mo, estimated 12-mo PFS/OS were 86%/94% (BR/CR), 89%/98% (BR/CR-A) and 87%/95% (BR-A). The proportion of treatment-related grade 3 or higher adverse events (AE) was 78%/88%/73%, with neutropenia in 52%/58%/27%, anemia in 23%/32%/3%, thrombocytopenia in 55%/66%/6%, and febrile neutropenia in 11%/12%/4%; treatment discontinuation due to AE occurred in 5%/7%/8% in BR/CR, BR/CR-A, and BR-A arms, respectively. Conclusion: High PET/CT CMR uMRD rates were seen in all 3 arms. BR/CR can be considered as a standard induction in pts ≤ 70. Addition of acalabrutinib to the standard arm added toxicity without improvement in efficacy, suggesting acalabrutinib should be avoided during Ara-C cycles. BR-A was found not superior and closed early by the DSMC; however, it is the least toxic arm with similar efficacy, and represents an appealing option to avoid high dose cytarabine.

Introduction: Bruton tyrosine kinase (BTK) inhibitors are highly effective against Waldenström macroglobulinemia (WM). Their effectiveness can be limited by resistance caused by BTK mutations and intolerance. BGB-16673 is a bivalent small molecule that induces BTK degradation by binding specifically to BTK and the E3 ligase. The E3 ligase catalyzes the transfer of ubiquitin molecules to BTK, which marks BTK for destruction by the proteasome. Preclinically, BGB-16673 degraded wild-type and mutant BTK associated with covalentand noncovalent BTK inhibitors (ncBTKis), leading to tumor suppression. CaDAnCe-101 (BGB-16673-101; NCT05006716) is an ongoing, open-label, first-in-human, phase 1/2 study evaluating BGB-16673 monotherapy in patients with a range of B-cell malignancies. Here, early results in patients with WM enrolled in the phase 1 portion are presented. Methods: Eligiblepatients must have confirmed R/R WM (≥2 prior therapies), an ECOG performance status of 0-2, and adequate organ function. Patients must have previously received an anti-CD20 antibody and, in the US and EU, a covalent BTK inhibitor (cBTKi). BGB-16673 was orally dosed once daily in 28-day cycles. Dose escalation used a Bayesian optimal interval design (6 planned dose levels, 50-600 mg once daily). Primary objectives were to evaluate safety/tolerability (CTCAE v5.0) and to establish the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Dose-limiting toxicities (DLTs) were assessed in the first 4 weeks (cycle 1). A secondary objective was to evaluate the overall response rate (ORR, IWWM-6 consensus criteria), with the first assessment occurring after 4 weeks of treatment. Results: As of May 24, 2024, 22 patients with WM were enrolled and treated (100 mg, n=4; 200 mg, n=10; 350 mg, n=8). The median age was 73.0 (range, 56-81) years, and the median number of prior therapies was 3.5 (range, 2-11), including prior cBTKis (n=22 [100%]), BCL2 inhibitors (n=4 [18%]), and ncBTKis (n=3 [14%]). Twenty patients (91%) had previously received chemotherapy. According to the International Prognostic Scoring System for WM, 6 patients (27%) had low-risk disease, 7 (32%) had intermediate-risk disease, and 8 (36%) had high-risk disease (missing/unknown data, n=1). Five patients (23%) had BTK mutations, 20 (91%) had MYD88 mutations, and 8 (36%) had CXCR4 mutations. The median follow-up was 4.3 (range, 0.3-21.3) months. Ninety-five percent of patients reported any-grade treatment-emergent adverse events (TEAEs; grade ≥3, 45%; serious, 23%), the most common (≥20%) of which were neutropenia/neutrophil count decreased (32%; grade ≥3, 23%), contusion (23%; no grade ≥3), and diarrhea (23%; no grade ≥3). The most common grade ≥3 TEAE (≥20%) was neutropenia/neutrophil count decreased. No atrial fibrillation, hypertension, febrile neutropenia, or major hemorrhage occurred. Three patients (14%) had a grade ≥3 infection (bronchopulmonary/cerebral aspergillosis, septic shock, and pseudomonal bacteremia/sinusitis). No patients had a TEAE that led to treatment discontinuation or dose reduction. No DLTs occurred, and the MTD was not reached. One patient (5%) died due to a TEAE (septic shock, considered related to disease progression). One patient died due to disease progression. In 21 response-evaluable patients (1 too early), the ORR (minor response or better) was 90%, the major response rate (partial response [PR] or better) was 81%, and the very good PR or better rate was 14%. Median time to first response was 0.95 (range, 0.9-3.7) months, with responses deepening over time. Seventeen patients remain on treatment and have ongoing responses. Responses were seen at the lowest dose (100 mg, 4/4), in patients previously treated with a cBTKi (19/21) and an ncBTKi (3/3), and in patients discontinued from prior BTKi due to disease progression (15/17). In addition, responses were observed in patients with and without mutations in BTK (with, 5/5; without, 6/8; unknown, 8/8), MYD88 (with, 18/20; without, 1/1), and CXCR4 (with, 8/8; without, 11/13). One patient had IgM flare at initial response assessment and went on to develop PR. Conclusions: Early data from this ongoing, first-in-human study demonstrate that the novel BTK degrader BGB-16673 has a tolerable safety profile and shows promising antitumor activity in heavily pretreated patients with BTK inhibitor-exposed R/R WM, including those with BTK and CXCR4 mutations.

Introduction: The BMT CTN 1704 study developed and validated the CHARM that stratified risk for non-relapse mortality and overall mortality among older adults, performing better than the HCT-CI alone (Artz A et al, Blood. 2023;142:109) and equally to two machine learning models. CHARM assigns a total score for 7 health variables: increasing age, higher HCT-CI scores, lower albumin, higher C-reactive protein, higher percent of weight loss over the preceding year, lower patient-reported performance status scores, and lower cognitive score per Montreal cognitive assessment (MoCA). A CHARM calculator is available at:https://cibmtr.org/CIBMTR/OffNav/DevSandbox/CHARM-Risk-NRM-Calculator No multi-institutional prospective data exist on functional trajectories and morbidity after HCT in older patients. We now report on the association of CHARM to trajectories of secondary morbidity outcomes among allo-HCT survivors of this large, prospective study. Patients and Methods: Allo-HCT candidates, aged ≥60 years (yrs), were enrolled (n=1226) from 49 centers in the US between 2019 - 2021. The primary analysis includes 1105 patients proceeding to allo-HCT on study and secondary endpoints were assessed at day (D) 100, 180 and 365 except MoCA and organ toxicity were restricted to D100 and frailty had inadequate data for D100. A sequential multiple imputation strategy was implemented to impute endpoints for survivors at each time point with missing data. Analyses on multiply imputed datasets were conducted and the results combined using Rubin's rule. Associations between CHARM scores and secondary outcomes were analyzed using a multivariable Cox, Fine-Gray, Generalized Estimating Equations, and logistic regression model for survival, competing risks, continuous, and binary outcomes, respectively, with latter two focused on surviving patients. Models were adjusted for other variables including conditioning intensity, graft-versus-host disease (GVHD) prophylaxis regimen, disease-risk index, donor-recipient gender match, ethnicity, baseline value of the dependent variable, and visit timepoints. Results: Higher CHARM scores were associated with development of serious organ toxicities by D100 (OR: 2.05, [1.52-2.78], p<0.0001) and ≥2 worsening score on the MoCA (odds ratio (OR) 1.55 [1.16-2.1], p=0.003). Among survivors at all timepoints, higher CHARM scores were associated with greater disability by instrumental activities of daily living (IADL) (Slope -0.640 [-0.433-0.846], p<0.001) and worsening Patient-Reported Outcomes Measurement Reporting System (PROMIS) physical function (Slope -0.981 [-0.057 - -1.904], p=0.037), depression (Slope 0.763 [0.042-1.484], p=0.038) and in a lesser magnitude anxiety (Slope 0.659, p=0.076). Among survivors at D180 and D365, higher CHARM scores were associated with worse frailty (Slope 0.193 [0.081-0.305], p<0.001). CHARM scores were not associated with development of acute GVHD grades 2-4 or 3-4 but were associated with post-GVHD increased mortality (HR: 1.61, [1.25-2.08], p=0.0002). Higher CHARM scores are associated with a lower incidence of chronic GVHD (HR: 0.83, p=0.026), likely due to the effect of CHARM on the competing risk of death leaving fewer patients at risk for chronic GVHD. Conclusions: The novel primary CHARM, originally developed to predict risks of NRM, also predicts worse frailty, disability, cognitive decline, and serious organ toxicities; outcomes that are critically important to older recipients of allo-HCT. CHARM therefore informs risks of transplant morbidity, separate from risks of developing acute GVHD. Results further support adopting CHARM in practice to counsel patients, expedite HCT referrals for lower risk CHARM, and design trials for high CHARM score patients.

Background: Inotuzumab Ozogamicin (InO) is an antibody-cytotoxin conjugate with high activity in B-cell acute lymphoblastic leukemia (B-ALL). InO targets the B-cell surface protein CD22, which is expressed in most B-ALL cases, albeit with great variability in expression levels. Emerging evidence suggest that this variation is associated with the stage of leukemia differentiation arrest [PMID: 21348573]. However, the exact relationship between CD22 expression and leukemia sensitivity to InO, particularly in the context of leukemia developmental state, remains unclear. Furthermore, our understanding of the molecular mechanisms regulating CD22 transcription in B-ALL is still incomplete. Methods: To comprehensively investigate the genomic basis of variability in leukemia CD22 expression and thus B-ALL sensitivity to InO, we performed a multi-omic characterization of 196 primary human B-ALL samples, using whole transcriptome sequencing (RNAseq), assay for transposase-accessible chromatin with sequencing (ATAC-seq), coupled with ex vivo profiling of InO sensitivity. Additionally, genomic editing studies were performed in Nalm6 and REH B-ALL cell lines, and patient derived xenograft (PDX) models were used for in vitro and in vivo validations. Results: Applying digital cytometry to leukemia bulk RNAseq data to infer the B-ALL developmental state, we found that blast cells with early Pre-pro-B-like signature had low levels of CD22 expression and were resistant to InO. As B-cell differentiation is controlled by stage-specific transcription factors (TFs), we performed a targeted CRISPR library screen of 1,639 TF genes and identified EBF1 as a key activator of CD22 expression (FDR=7.1x10-4). In primary B-ALL samples, EBF1 expression was significantly correlated with CD22 expression (R=0.69, P<0.0001) and leukemia response to InO (measured as LC50, R=-0.42, P<0.0001). In addition, TF footprint analysis of leukemia ATAC-seq data identified EBF1 as the most differentially activated TF comparing InO-sensitive and -resistant B-ALL cases (P=8x10-174). Blocking the EBF1 binding sites within the CD22 promoter by CRISPR interference resulted in a 50-fold and 49-fold decrease in cell surface CD22 expression, and a 22-fold and 25.7-fold increase in InO LC50 for Nalm6 and REH, respectively, confirming the direct impact of EBF1 on CD22 transcription and InO sensitivity. Because BCR::ABL1-positive ALL showed the greatest variability in InO sensitivity among all B-ALL subtypes, we further investigate the role of the EBF1/CD22 axis on InO sensitivity within this subtype. Unsupervised clustering of gene expression profiles revealed two distinct groups, namely BCR::ABL1 ALL with multilineage (BCR::ABL1-M) or lymphoid only (BCR::ABL1-L) involvement [PMID: 38153913]. Compared to BCR::ABL1-L, BCR::ABL1-M displayed markedly reduced CD22 expression (P=8.3×10-11) and resistance to InO (P=1.9×10-4), likely due to the lower expression and frequent somatic alteration of EBF1. Finally, we established PDX models for representative cases of BCR::ABL1-M and BCR::ABL1-L. Strikingly, InO treatment did not affect leukemia progression in the BCR::ABL1-M PDX model, whereas the BCR::ABL1-L PDX model achieved complete remission and has remained leukemia free to date. Conclusion: Collectively, these data demonstrate the direct impact of EBF1 on CD22 expression during B-cell development, and explain the heterogeneity of InO sensitivity, even within the same molecular B-ALL subtype.

Introduction: GOLCA is a potential first-in-class oral cereblon E3 ligase modulator (CELMoD™) agent for non-Hodgkin lymphoma, purposefully designed to target Ikaros/Aiolos and have favorable pharmacokinetics, resulting in apoptotic and immunomodulatory activity with preferential distribution to lymphoid organs. CC-220-DLBCL-001 (NCT04884035) is an ongoing phase 1b, open-label, multicenter, dose-escalation/expansion trial to assess safety and preliminary 1L GOLCA + R-CHOP efficacy in a-BCL. Although longer follow-up is needed to assess durability of response, MRD negativity (MRD-) is an emerging endpoint in a-BCL. Achieving MRD- on and at end of treatment (EOT) can potentially predict clinical benefit. This study aimed to analyze circulating tumor DNA (ctDNA) kinetics of GOLCA + R-CHOP across the trial population and in defined patient (pt) segments-cell of origin (COO), high baseline ctDNA, and high-risk genomics-and to correlate MRD- with imaging and clinical outcomes. Methods: Eligible pts were ≥ 18 years of age with ECOG performance status ≤2, IPI 0-5 in Part 1 and 2-5 in Part 2, and untreated a-BCL with measurable disease. Pts were treated with GOLCA + R-CHOP for 6 x 21-day (D) cycles (C) or until disease progression/unacceptable toxicity/study withdrawal. Dose escalation phase GOLCA dose levels (DLs) were 0.2 mg D1-7 (DL-1), 0.4 mg D1-7 (DL1), or 0.4 mg D1-10 (DL2). During dose expansion, pts were randomized 1:1 to R-CHOP + GOLCA DL-1 or DL1. The primary endpoint was safety of GOLCA at DL1; efficacy was a secondary endpoint, ctDNA was an exploratory endpoint. ctDNA was analyzed using the PhasED-Seq assay (<10-6 sensitivity) at baseline, C2D1, C3D1, and EOT. MRD- was defined as the absence of detectable ctDNA on-treatment. Pretreatment biopsies were sequenced by whole genome sequencing (WGS) and whole transcriptome sequencing (WTS). Results: At data cutoff (June 3, 2024), the median follow-up was 14.3 months. One-year progression-free survival (PFS) was 85.3% at 0.4 mg and 77.3% at 0.2 mg. Rates of MRD- increased over time but were consistently higher at 0.4 vs 0.2 mg, with values of 44% (14/32) vs 29% (8/28) at C2D1; 63% (17/27) vs 54% (15/28) at C3D1, and 90% (26/29) vs 73% (19/26) at EOT, respectively. Interim MRD- at C3D1 strongly predicted EOT MRD-; all 0.4 mg pts and all but two 0.2 mg pts who were MRD- at C3D1 remained MRD- at EOT. In contrast, fold-changes from baseline ctDNA were similar between 0.4 mg and 0.2 mg. The early molecular response rate (≥102-fold drop from baseline at C2D1) was 81.2% (26/32) at 0.4 mg and 82.1% (23/28) at 0.2 mg. The major molecular response rate (≥102.5-fold drop from baseline at C3D1) was 88.9% (24/27) at 0.4 mg and 85.7% (24/28) at 0.2 mg. Across genetically defined pt segments, EOT MRD- at 0.4 mg was prevalent for both COO subtypes measured by the Hans algorithm: 94% (17/18) among germinal center B-cell (GCB) and 75% (6/8) among non-GCB pts. Of the 29 pts with baseline genomics, 13 were genomically high risk: p53 mutant (VAF >0.5), DZsig and/or A7 subtype. In these pts, EOT MRD- was 80% (4/5) at 0.4 mg but only 20% (1/5) at 0.2 mg. In high baseline ctDNA (>102.5 hGE/mL) pts who were high-risk for R-CHOP failure, EOT MRD- at 0.4 mg was 86.7% (13/15) vs 57.1% (8/14) at 0.2 mg. There was an association between high baseline ctDNA and lower PFS at 0.2 mg (HR, 4.56 [95% CI, 0.53-39.12]), but interestingly the association decreased at 0.4 mg (HR, 2.10 [95% CI, 0.19-23.5]). Combining both arms, MRD- at both C3D1 and EOT trends with improved PFS (C3D1: HR, 0.73 [95% CI, 0.2114-2.523]; EOT: HR, 0.53 [95% CI, 0.1103-2.592]); longer follow-up may be required to demonstrate significance. Conclusions: Interim and EOT levels of MRD- were higher at 0.4 mg vs 0.2 mg GOLCA, with a one-year PFS of 85.3% vs 77.3%, respectively. Although pt numbers were small, the data suggest that 0.4 mg is efficacious in high-risk ctDNA and high-genomic risk pts, independent of COO, and support the 0.4 mg GOLCA + R-CHOP regimen in the randomized phase 3 trial GOLSEEK-1. Interim MRD- may play a role in future adaptive trial designs.

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: Erdheim-Chester Disease (ECD) is an exceedingly rare inflammatory myeloid neoplasm characterized by infiltration and accumulation of clonal histiocytes within multiple organ systems. These histiocytes usually carry gain-of-function mutations that affect the MAPK-ERK or PI3K-AKT pathways. The most common mutation is BRAFV600E, occurring in greater than 50% of patients, often with a low variant allele frequency (i.e. <5%). ECD presents as a spectrum of clinical manifestations that include symmetric osteosclerosis of the distal femora and proximal tibiae and/or fibulae (almost always present), ataxia from cerebellar/brainstem involvement, diabetes insipidus, periorbital xanthelasmas, pleuropulmonary disease, pseudotumor of the right atrioventricular groove, encasement of the (coated) aorta, and retroperitoneal involvement with ‘hairy’ kidneys. Patients may be asymptomatic or critically ill. Treatment options include targeted agents like BRAF or MEK inhibitors, as well as systemic agents such as interferon or chemotherapy. A recent combined report from France and Italy suggested incidence rates of 3.5 per 10 million adults (not age-adjusted). ECD was officially considered a hematopoietic malignancy by the World Health Organization in 2016 and a reportable cancer in the United States (US) beginning in 2021. For the first time, we report the incidence of ECD in the US. Methods: We obtained ECD data in 2021, the only year available so far, from the Surveillance Epidemiology and End Results (SEER) program. The SEER program prospectively collects data from population-based cancer registries covering about 48% of the US population and is updated annually. Data elements include patient demographics, primary tumor site, tumor morphology and stage at diagnosis, first course of treatment, and follow-up for vital status. Twentytwo cancer registries (SEER 22) were included and screened for cases with the ECD International Classification of Diseases for Oncology (ICD-O) code 9749/3 for inclusion in this study. We used SEERstat version 8.4.3 to calculate the annual incidence. All incidence rates were age-adjusted to the 2000 US standard population. Confidence intervals (CI; 95%) were provided whenever available. Results: In 2021, SEER documented 16 patients diagnosed with ECD. The median age at diagnosis was 52 years (range, 25-74). The most common age range at diagnosis was 55-59 years (31%). There was an even distribution of sexes (53% male), but greater proportion of minority patients (38% non-Hispanic White, 25% non-Hispanic Black, 25% Hispanic, 6% Asian/Pacific Islander, 6% unknown race/ethnicity). Most patients (94%) were diagnosed in large metropolitan areas. The overall incidence rate was 0.9 [CI: 0.2-5.2] per 10 million population. The incidence rates for various demographic subgroups were as follows (per 10 million): males (1.0 [0.4-1.9]), females (0.8 [0.4-1.7), non-Hispanic Blacks (1.9 [0.5-5.2]), Hispanic (1.1 [0.3-2.8]), non-Hispanic Whites (0.5 [0.2-1.2]), Asian/Pacific Islander (0.5 [0.0-3.4]), and ages 25-74 years (1.5 [0.8 - 2.5]). The most reported primary site was subcutaneous (25%), followed by bone (19%) and breast (19%). A greater number of cases had distant disease (56%; 31% localized, 13% unknown). Almost half of the patients received chemotherapy (44%) and few underwent radiation (13%) or surgery (13%). Conclusion: We report the first estimate of ECD incidence in the US, highlighting the rarity of this entity. It should be noted that our reported incidence rates are likely underestimated. This could be due to the COVID-19 pandemic that resulted in social quarantine from 2020-2021. ECD is also a very challenging diagnosis to make. Future investigations of annual SEER updates and collective incidence data over several years will be required to strengthen our findings and further characterize the epidemiological features of ECD in the US.

Background: Two National Cancer Institute-funded pharmacovigilance programs have identified 49 serious hematology-related ADRs since 1998. The programs, called RADAR (Research on Adverse Drug events and Reports) and then SONAR (Southern Network on Adverse Reactions) involve > 50 institutions and > 75 co-investigators worldwide. The work builds on three prior studies evaluating “Davids and Goliaths” in medical oncology and in cardiology (PLOS One, eClinicalMedicine, and Journal of Scientific and Professional Integrity). Here we review the hematology focused safety investigations of RADAR/SONAR. Methods: Data were based on initial safety signals being identified by a RADAR/SONAR co-investigator. Then, case-series were derived. Collaborations with basic scientists allowed for basic science correlative studies. Results were disseminated primarily as Brief Report in the literature and Black Box warnings on the related drug. In some instances, studies identified hematologic toxicities that prevent FDA from approving a submitted drug application. Results: sADRs were frequently identified based on very small case series, including ticlopidine-and clopidogrel associated thrombotic thrombocytopenic purpura (22 and 10 patients, respectively), thalidomide- and lenalidomide-associated venous thromboembolism (9 and 5 patients, respectively), rituximab-associated progressive multi-focal leukoencephalopathy (22 patients), peginesatide-associated fatal anaphylaxis (5 patients), and COVID-19 vaccine associated immune thrombocytopenia (1 patient). Meta-analyses provided data for epoetin- and darbepoetin-associated mortality among cancer patients and lenalidomide- and thalidomide-associated venous thromboembolism. Following the onset of the COVID-19 pandemic, RADAR/SONAR investigated social media and pre-prints (COVID-19 vaccine associated cerebral vein thrombosis and immune thrombocytopenia). Time from FDA approval to sADR discovery was a median of 5 years (range, 0 months (thalidomide-associated venous thromboembolism) to 34 years (ciprofloxacin-associated neuropsychiatric toxicity). Basic science correlative studies identified ADAMTS13 autoantibodies (ticlopidine), leachates that developed in a multi-dose vial (peginesatide), anti-red blood cell antibodies (epoetin-associated pure red cell aplasia), and high-risk genes (fluoroquinolones and rituximab). Overall, RADAR/SONAR studies are estimated to have saved over 1 million lives and also resulted in overall payments to the Department of Justice of $1.5 billion (related to marketing of unsafe drugs). Discussion: RADAR/SONAR has proven to be a very important adjunct to FDA and pharmaceutical manufacturer-led safety investigations for hematology, paralleling the success in medical oncology and in cardiology. Going forward, independent centers of excellence for safety-focused investigations such as the CERSI network and the SENTINEL network (both are NIH funded) should be broadened to include a hematology-focused safety center.

Background: Randomized studies in newly diagnosed (ND) AML patients with a FLT3 mutation show that adding 14 days of a FLT3 inhibitor to each intensive chemotherapy cycle improves overall survival. For patients unsuitable for intensive chemotherapy due to older age or comorbidities, the presence of a FLT3-ITD mutation is associated with high rates of early relapse and short remission duration. There is a limited survival benefit of venetoclax (ven) plus azacitidine (aza) compared to aza alone among patients with AML with a FLT3-ITD mutation. Accordingly, there is significant interest in adding FLT3-targeted therapy to lower intensity chemotherapy for patients with ND AML and FLT3 mutations, but to date no randomized data have demonstrated a survival benefit for this approach.Gilteritinib (gilt) is a highly potent and FLT3-selective oral tyrosine kinase inhibitor that is the standard therapy of relapsed/refractory FLT3-mutated AML, based upon superior survival in randomized studies. Gilt can also be combined safely with ven and/or aza, though myelosuppression remains a concern. Despite this, single institution studies of ven, aza, and gilt therapy of ND AML patients with FLT3-mutations show that this three-drug regimen is associated with near-universal complete remission rates (CR 90%, CRi 6%) and a majority of studied patients eliminate detectable FLT3-ITD (<1 x10-5) within four cycles by an ultrasensitive, amplicon-based NGS assay (Short, et al. JCO 2024). Rates of CR with full count recovery and survival appear superior to historical comparisons, but myelosuppression is potentially increased with the triplet regimen. These data demonstrate a need for multi-institutional comparative trials, not only to determine whether adding FLT3-inhibitors to ven and aza improve deep remission rates, but also to refine schedules of the triplet combination that improve tolerability for widespread use.Methods: This tier 1 MyeloMATCH substudy is an open-label, randomized phase 2 trial that will enroll ND AML patients older than age 60 or individuals judged by their treating physician to be best served by azanucleoside + ven-based therapy due to comorbidity. Subjects provide samples to the central MyeloMATCH Master Screening and Reassessment Protocol (MSRP, NCT05564390 ) and are assigned to the MM1OA-EA02 substudy (NCT06317649) based upon the presence of a FLT3-ITD or FLT3-TKD (D835) mutation by NGS. Subjects are randomized to one of three arms (regimens 1, 2, or 3), stratified by age (<70 years vs. older) and FLT3-ITD burden (ITD VAF>33% vs. lower VAF or D835). All study arms contain aza and ven administered in 28-day cycles with two study arms also including gilt. Regimen 1 is ven and aza administered as per the pivotal VIALE-A study. Regimen 2 adds gilt 80 mg once daily on days 1-28 and regimen 3 adds gilt on days 8-21 only. A marrow biopsy is performed during the first cycle (day 14-21, depending on study arm) and all chemotherapy is held until count recovery if a morphologic leukemia-free state or aplasia is seen. Patients receive up to two induction cycles to achieve remission and then receive ongoing consolidation cycles of therapy with a similar pattern of gilt administration up to 2 years. To minimize risk of cumulative myelosuppression, during consolidation azacitidine administration is reduced to days 1-5 on regimens 2 and 3 and ven limited to days 1-7 on regimen 2 and days 1-14 on regimen 3. For all arms, treatment-related adverse events prompt further reduction in ven, aza, or gilt dose or duration. Response will be measured after cycles 2 and 4, including centrally-performed MRD by flow cytometry. The primary endpoint is the rate of MRD(-) CR (<1 x 10-3) after up to 4 cycles. Key secondary endpoints include safety data, response rate, EFS, and OS. The study is powered to detect a 25% absolute improvement in MRD(-) CR rate in either triplet arm from a target accrual of 147 patients. A safety run-in for regimens 2 and 3 to confirm tolerability and feasibility will be performed after 20 subjects enroll to these arms; an interim futility analysis will be performed once response assessment of 50% of all planned accrual occurs. Study was activated on June 6, 2024 and is expected to continue until December 2025.