Hefazi, Mehrdad

Abstract Background: Clonal cytopenia of undetermined significance (CCUS) is defined as clonal hematopoiesis in the absence of a hematologic neoplasm, along with unexplained cytopenia. While several studies have identified risk factors and developed scores to predict progression to overt myeloid neoplasms, the clinical and molecular features during the progression process remain poorly understood. Aim: Evaluate the clinical and clonal characteristics of patients with CCUS, with a focus on the longitudinal evolution of clonal and clinical parameters over time. Methods: After IRB approval, we retrospectively reviewed charts of patients with unexplained cytopenia (2015-2024), recording data at the time of CCUS diagnosis (WHO 2022 diagnostic criteria) and at time of follow-up bone marrow biopsy after diagnosis. Follow-up CBC and karyotype data were recorded for patients who had repeat bone marrow biopsies (n= 111), while follow-up clonal parameters and risk scores were calculated for those who underwent repeat NGS (n= 74). A reduction or expansion in clone size was defined as a change exceeding 5% (CE5%), or change exceeding 10% (CE10%) from the baseline value. Overall survival (OS) was calculated from diagnosis to last follow-up. For statistical analysis, we used BlueSky Statistics V10.3.1. Results: 214 CCUS patients (median age 73, 68% males) were included. At baseline, 30% of patients had abnormal cytogenetics, with del (20q) being the most common one (8%; n= 18), followed by trisomy 8 (6%; n= 13), and loss of chromosome Y (5%; n= 10). The median number of mutations was 2 (range, 1-5), with the most common mutations TET2 (38%), SRSF2 (21.5%), ASXL1 (21%), ZRSR2 (18.5%), DNMT3A (9.5%), and U2AF1 (9%). Most patients had high risk CHRS (60%), followed by intermediate (30%), and low risk (10%). On the other hand, 41% had high risk CCRS, 29% had intermediate risk, and 30% had low risk. After a median follow-up of 46 months, 62 patients died (median OS not reached). A decrease in the white blood cell (WBC) count from the time of diagnosis to follow-up was more frequently seen among CCUS patients who progressed to MN (70% vs 50%, p= 0.04), however, changes in hemoglobin and platelets did not differ between those who progressed and those who did not (p> 0.05). Although the frequency of abnormal karyotypes at diagnosis was similar between patients who eventually progressed (28%) and those who did not (31%) (p= 0.6), 4 (2%) patients with initially normal karyotypes acquired chromosomal abnormalities during follow-up, and all progressed to MDS. Among the 74 patients who had follow-up NGS, 31% acquired new mutations, clonal expansion of pre-existing mutations were seen in 54% using CE5% and 19% per CE10%, and 16% developed new variants of uncertain significance (VUS). Acquiring new pathogenic mutations was similar in patients who progressed to MN compared to those who did not progress (34% vs 28%, p= 0.6). On the other hand, clonal expansion was significantly more observed in patients who progressed compared to those who did not, using both CE5% (73% vs 31%, p = <0.001) and CE10% (27% vs 9%, p= 0.03). At follow-up, ASXL1 was the most commonly acquired mutation among patients who did not progress (4 cases), followed by TET2 (2 cases), and U2AF1, GATA2, DNMT3A, SF3B1, ZRSR2, TP53, and CBL (1 case each). On the other hand, SRSF2, SETBP1, CBL, JAK2, TET2, and RUNX1 were more frequently acquired among those who progressed to myeloid neoplasms (each appeared in 2 patients). When recalculating CCRS, CHRS, IPSS-M, and IPSS-R at follow-up for patients who had repeat NGS, there was no significant difference in score changes - either upward or downward - between those who progressed and those who did not (p> 0.05). Conclusion: In CCUS patients who progressed to myeloid neoplasms, WBC decline, clonal expansion (more frequent), and evolving chromosomal aberrations (less frequent) were observed, supporting the value of longitudinal genomic and clinical monitoring in CCUS.

Abstract The importance of bone marrow (BM) microenvironment and its immune interactions within and their role in chronic myelomonocytic leukemia (CMML) disease progression have not been well studied. Our previous work in CMML identified type 1 helper T cell (Th1) and CD4 terminal effector cell suppression in peripheral blood from untreated patients, in comparison to age-matched normal controls (Mangaonkar A et al. Blood Adv 2020). Furthermore, clonal dendritic cell (DC) aggregates in CMML are present in approximately 20-30% patients at diagnosis, display significant cell heterogeneity (plasmacytoid DCs + myeloid DCs and other myeloid/immune cells), express indoleamine 2,3-dioxygenase-1 (IDO), associate with T regulatory cell (Treg) expansion, and transformation to AML [blast transformation or BT, Lucas N et al. Leukemia 2019, Mangaonkar A et al. Blood Adv 2020, and Mangaonkar A et al. Blood 2023 (abstract)]. The purpose of this study was to define the myeloid-immune cell interactions within the BM microenvironment critical for CMML progression to AML. To phenotypically identify cell types and their interactions within the CMML BM, we used single-cell type spatial omics through two distinct modalities on archival formalin-fixed paraffin-embedded (FFPE) BM biopsy specimens. Ten serial CMML samples at chronic phase [CP, n=5, median BM blast% 5 (2-15)] and at BT [n=5, median BM blast% 60 (25-74)] were used for both techniques. Spatial transcriptomics was conducted through GeoMx Digital Spatial Profiler (DSP) platform that uses UV-photocleavable, spatial-barcoded oligo probes to profile the whole transcriptome in defined regions of interest (ROI). CD123 (marker for DC-myeloid aggregates) immunofluorescence antibody was used to identify and segment ROI. 16-color flow cytometry was done to validate cell-specific expression. Spatial cellular phenotyping of immune cells on the same samples (serial cuts) was done through multiplex imaging by co-detection by indexing (CODEX) using 27 markers: CD31, Ki67, CD11b, CD20, CD44, Ecad, CD123, CD107a, CD8, CD11c, CD45RO, FoxP3, CD14, PDL1, CD56, CD68, CD163, PD-1, CD38, HLA-DR, CD4, IDO, CD45, PanCK, Na/K/ATPase, CD3e, and DAPI. CD8T+ cell anergy was demonstrated through CFSE cell proliferation assay. Benjamini-Hochberg correction was used to adjust for multiple hypotheses. After filtering poor quality ROIs [ROIs with total read count < 1000 were removed, ROIs with trim, stitch, alignment < 80% or saturation < 50% were removed], 3rd-quartile normalization [BiocGenerics (v. 0.48.1)] and batch correction [limma (v. 3.58.1)], we compared transcriptomics signatures between CD123+ and CD123- ROIs in all samples. Results showed that LIPA, SLC4A1, HBA2, TIMD4 and HMOX1 werethe top five genes upregulated in CD123+ areas. Among all gene transcripts, TIMD4 expression increased the most (Log2FC=0.6, P-value=8.79E-10, FC=1.52, FDR=1.68E-07) when CD123+ ROIs were compared between CMML-CP and CMML-BT serial samples, suggesting a biological relevance in disease progression. Previous work in metastatic peritoneal cancer has established that TIM-4 expressing macrophages suppress Th1/Th2 ratios and impair CD8+ T cell function (Chow A et al. Cancer Cell 2021). To confirm expression at the protein level, we used a multicolor flow cytometry panel and confirmed that TIM4 is expressed on macrophages (Lineage-negative, HLA-DR+, CD68+ cells) in independent CMML BM aspirate samples (n=3). Next, we conducted spatial phenotyping using CODEX on serial cuts from the same serial samples used for spatial transcriptomics. Anatomical co-localization of macrophages with leukemic cells, monocytes and T cells was visually inspected and confirmed. Cell-interaction analysis (after Benjamini-Hochberg correction) indicated that macrophages-monocyte, macrophage-leukemic cells, and macrophage-memory CD4+T cells were significantly (P<0.05) increased in CMML-BT versus CMML-CP. CD8T+ cell anergy was confirmed through a CFSE cell proliferation assay in untreated CMML PBMC samples. In conclusion, our data suggests that TIM4-expressing macrophages and their interactions with monocytes/monocyte precursors and immune cells within a DC aggregate create a protective leukemic stem cell niche and T cell tolerance, promoting blast transformation in CMML.

Abstract Background: Isocitrate dehydrogenase (IDH) mutations are frequently implicated in the development of acute myeloid leukemia (AML). In a recent study (Salman MY, Blood Adv 2025), it was reported that IDH2 mutation subtypes, R140 and R172, may respond differently to intensive chemotherapy. In this study, we evaluated mid-cycle and end-of-cycle bone marrow blast responses in AML patients with IDH2 R140, IDH2 R172, and IDH1 R132 mutations, aiming to determine whether these subtypes exhibit different response dynamics. Methods: We reviewed the charts of AML patients diagnosed at Mayo Clinic, Rochester, between the years 2016 - 2023 that had available next generation sequencing (NGS) data. Institutional review board approval was obtained. All data were recorded at the time of AML diagnosis. Patients without molecular data or not treated with intensive chemotherapy (7+3 or CPX-351) were excluded from this study. Bone marrow blast percentages were assessed at mid-induction (days 14-21) and end of cycle (counts recovery). Blast clearance dynamics and complete remission rates were compared across IDH mutation subgroups and correlated with outcomes. GraphPad Prism 10.0.0 was used for statistical analysis. Results: Out of 381 AML patients, 31 had IDH2 mutations (23 with R140 and 8 with R172), and 8 had IDH1 mutations (all R132). Among patients with IDH2 mutations, those with R172 had numerically higher median mid-cycle bone marrow blast percentage compared to R140 (10% vs. 4%, p = 0.37). There was no significant difference in mid-cycle blast percentages between patients with IDH1 and IDH2 mutations (4.5% vs. 4%, p = 0.8). At mid-cycle, 68% of patients with IDH2 R140 had blast counts <5%, compared to 38% of those with IDH2 R172, suggesting a trend for faster mid-cycle clearance in the R140 group, though not statistically significant (OR 3.57, p = 0.2). In a broader comparison, 60% of IDH2-mutated patients and 50% of IDH1-mutated patients achieved blast clearance (blasts <5%) at mid-cycle, though not statistically significant (p = 0.7). At the end of the induction, patients with IDH2 R140 had significantly lower median bone marrow blast percentages compared to those with R172mutations (2% vs. 4%, p = 0.01). Similarly, patients with IDH1 mutations showed low blast counts compared to the IDH2 group (1.5% vs. 3%, p = 0.1). A higher proportion of IDH2 R140 patients achieved blast clearance compared to those with R172 mutations (100% vs. 75%, p = 0.06), while proportion of patients who achieved blast clearance were similar between IDH1 and IDH2 patients (87.5% vs 93.1%, P = 0.5). Analysis of overall complete remission rates (including both complete remission [CR] and CR with incomplete hematologic recovery [CRi]) within the IDH2-mutated group showed a higher rate in patients with the R140 mutation compared to those with R172 (87% vs. 75%), though the difference was not statistically significant (p = 0.5). When comparing IDH1- and IDH2-mutated patients, overall complete remission rates were 75% and 84%, respectively, with no significant difference observed (p = 0.6). Kaplan–Meier analysis of time to end-of-induction blast clearance revealed no statistically significant difference between IDH2 R140 and R172 patients (median time to clearance: 31 vs. 37 days, p = 0.3). Similarly, no difference was observed between IDH1 and IDH2-mutated patients (33 vs. 31 days, p = 0.9). Overall survival analyses showed no significant difference between IDH2 R140 and R172 groups (median 66.8 months vs not reached, P = 0.4). Likewise, no difference was observed between IDH1 and IDH2 patients (44.4 months vs not reached, P = 0.7), indicating similar overall survival across mutation subtypes. Conclusion: IDH2-R140 was associated with more effective blast cytoreduction following intensive induction compared to IDH2-R172. Although not statistically significant, IDH2 R172consistently showed trends toward higher blast percentages, delayed response, and lower overall complete remission rates. These findings align with the recent study reporting significantly slower blast reduction and delayed response in R172-mutated AML. Also, no significant differences were found between IDH1- and IDH2-mutated patients in terms of response kinetics or overall survival. Together, these findings highlight potential biological differences among IDH mutation subtypes that may impact treatment response and require further investigation in larger prospective cohorts.

Abstract B cell maturation antigen (BCMA)-targeted chimeric antigen receptor T (CART) cell therapies have emerged as a potentially curative treatment for multiple myeloma (MM). However, 50-70% of patients relapse within 3 years. The MM tumor microenvironment (TME) is highly immunosuppressive with an abundance of bone marrow (BM) cancer-associated fibroblasts (CAFs), which contribute to BCMA-CART cell failure. Therapeutic targeting of BM-CAFs has been beset by 1) an incomplete understanding of CAF interactions with CART cells and other BM cells and 2) toxicity risks due to prolonged depletion of healthy fibroblasts and inefficient drug delivery to the BM. To elucidate how BM-CAFs drive BCMA-CART resistance, we performed single cell RNA sequencing (scRNAseq) of baseline BM aspirates from responders (R, n = 6) and non-responders (NR, n = 6) to BCMA-CART cell therapy. NR BMs were enriched for inhibitory CAFs (iCAFs) that highly express fibroblast activation protein (FAP). Spatial analyses of BM cells revealed greater iCAF-iCAF and iCAF-inhibitory macrophage interactions in NR. These findings suggest that FAP+ iCAFs in NR are abundant in the BM and exhibit significant interactions with immunosuppressive macrophages. Next, we sought to validate our scRNAseq data in preclinical models. Xenograft mice were intravenously (IV) engrafted with luciferase+ (luc+) BCMA+ OPM2 cells and/or patient-derived (pd) BM-CAFs (1x106 each). Following engraftment, mice received 1x106 BCMA-CART cells (IV). BCMA-CART cells eradicated tumors in mice engrafted with OPM2 cells, but not in mice engrafted with pdBM-CAFs and OPM2 cells (p<0.01). In NSG and humanized mice (NSG mice engrafted with human CD34+ cells in the first 48 hours of life), tumor growth was significantly accelerated in the presence of pdBM-CAFs (NSG: p<0.01; humanized: p<0.001). BCMA-CART, OPM2, and pdBM-CAF co-cultures also showed significant increases in immunosuppressive cytokines including IL-1Rα, IL-4 and IL-10 and inhibited CART cell proliferation compared to co-cultures without pdBM-CAFs (IL-1Rα, IL-10: p<0.01; IL-4: p<0.001; proliferation: p<0.05). To overcome CAF-mediated CART dysfunction, we engineered BCMA-CART cells to secrete molecules to target BM FAP+ iCAFs and remodel the MM-TME (STriKEs). We designed two BCMA-CART-STriKE strategies: 1) a tri-specific composed of IL-15, anti-FAP, and anti-CD16 molecules to activate innate immune cells to kill CAFs and 2) bi-specific anti-FAP, anti-SIRPα molecules linked to an antibody Fc region (Fc fusion) targeting the CD47/SIRPα axis to induce phagocytosis of FAP+ iCAFs. We hypothesized that BCMA-CART-STriKEs would surmount CAF-mediated immunosuppression without toxicity. We generated BCMA-CART-STriKEs from healthy human donor T cells. CAR expression, STriKE secretion, and binding were confirmed via flow cytometry. Co-cultures of BCMA-CART-STriKEs, donor-matched macrophages, OPM2 cells or BCMA+ MM1S cells, and pdBM-CAFs showed significantly higher OPM2 or MM1S killing (p<0.001), immune cell activation (p<0.01), and phagocytosis (p<0.05), compared to control BCMA-CART cells secreting IL-15 or Fc fusions targeting only FAP or only SIRPα. Next, we assessed BCMA-CART-STriKE efficacy in vivo. NOD-SCID-γ-/- (NSG) mice received 1x106 pdBM-CAFs and 1x106 luc+ OPM2 or luc+ MM1S cells via IV or subcutaneous (SQ) injection. Mice were randomized after confirming tumor engraftment (via bioluminescence imaging for IV or tumor caliper for SQ) and received IV treatment with 1x106 BCMA-CART-STriKEs (or controls) and 5x105 donor-matched macrophages or CD16+ immune cells. BCMA-CART-STriKE-treated mice achieved total tumor clearance. Treatment with BCMA-CART cells secreting IL-15 led to lethal weight loss despite tumor clearance while BCMA-CART cells secreting Fc fusions targeting only FAP or SIRPα failed to eradicate tumors. Lastly, we assessed the potential toxicities of BCMA-CART-STriKEs in humanized mice engrafted with OPM2 cells and pdBM-CAFs (1x106 each). CART cells expressing BCMA and FAP CARs (BCMA-FAP CART) served as a control. BCMA-FAP CART treatment resulted in significant toxicity and weight loss while BCMA-CART-STriKE treatment did not (p<0.01). In summary, we have identified iCAF interactions with immunosuppressive immune cells as key contributors to BCMA-CART cell failure and designed novel BCMA-CART-STriKEs that overcome this failure in MM preclinical models. These findings support the translation of BCMA-CART-STriKEs to a phase I clinical trial.

Abstract Prognosis in acute myeloid leukemia (AML) patients is influenced by various factors, most importantly, patient clinical status and cytogenetic/molecular abnormalities. Within those factors, elevated lactate dehydrogenase (LDH) is considered a poor prognostic indicator in AML patients. Our study aims at exploring the different factors associated with elevated LDH and their impact on overall survival (OS). After obtaining IRB approval, we reviewed the charts of 381 AML patients diagnosed at Mayo Clinic, Rochester, between the years of 2016 and 2023. All data was recorded at the time of AML diagnosis. Patients with no cytogenetic and molecular data were excluded from this study. LDH levels were recorded if measured within 10 days of diagnosis and treatment for AML was not yet given. Both risk stratification and response evaluation were done following the 2022 European LeukemiaNet (ELN) guidelines. OS was calculated from the date of AML diagnosis to the date of last follow-up or death. We used BlueSky Statistics V 10.3.4 for statistical analysis. We identified 299 patients (78.4%) who had elevated LDH levels (normal ≤ 222 U/L) at the time of diagnosis with a median of 417 U/L (range, 223-7989). The median age for those patients was 68 years (range, 18-94), with 78 (26.1%) of them having a prior myeloid disease (MDS, MPN, or MDS/MPN) before AML diagnosis. By risk stratification, more than half of the patients had an adverse risk profile (n=171, 57.2%), while 71 (23.7%) and 57 (19.1%) had an intermediate and favorable risk, respectively. Most of those patients had an abnormal karyotype (n=204, 68.7%), with complex karyotype (n=103, 34.7%) being the most common abnormality, followed by monosomy 7 (n=50, 16.8%) and trisomy 8 (n=46, 15.5%). Next-generation sequencing (NGS) was performed on 268 (89.6%) patients with elevated LDH, and the most common mutations were TP53 (n=60, 22.3%), FLT3-ITD (n=59, 21.1%), and NPM1 (n=51, 18.5%). TP53 mutations were more common in patients with normal/low white blood cell count (WBC) in contrast with FLT3 and NPM1, which were the most common mutations in patients with high WBC. After grouping the patients according to their LDH levels (group 1: 223-444 U/L, group 2: 444-666 U/L, group 3: > 666 U/L), we found that FLT3-ITD mutations were more likely to occur at higher LDH levels i.e. groups 2 and 3 (p= 0.002). The majority of patients with elevated LDH (n=262, 87.6%) received therapy following diagnosis, with the most common treatment regimens being a combination of a hypomethylating agent and venetoclax (HMA+VEN) (n=97, 37%) and a (7+3)-based induction therapy (n=77, 29.4%). When comparing patients with elevated LDH (n=299, 78.4%) to patients who had non-elevated LDH (n=82, 21.5%), no difference in both median age at diagnosis and risk stratification was found. We noticed an increase in WBC (median, 7.7 vs. 2.1) (p<0.001) along with an increase in peripheral blasts (median, 28% vs. 7%) (p<0.001) in elevated LDH patients. Among patients with non-elevated LDH, 21% (n=17) had a complex karyotype compared to 34.7% (n=103) in the elevated LDH group (p=0.022). The molecular profile was different between the 2 groups, where the most common mutations in patients with non-elevated LDH were IDH2 (n=19, 25.3%), RUNX1 (n=17, 23%), and DNMT3A (n=16, 21.6%). All patients (n=82, 100%) in the non-elevated LDH group received therapy after diagnosis. There was no difference in terms of treatment regimens used between the 2 groups. Moreover, no statistical difference in remission rates after one line of therapy was found between those groups where non-elevated LDH patients had a 65.9% remission rate compared to the 55.3% remission rate in patients with elevated LDH (p=0.098). Patients with elevated LDH had a shorter OS than patients with non-elevated LDH (9.5 vs. 26.4 months, p=0.0008). However, median OS was similar across the different groups of elevated LDH. Using univariate analysis in our cohort (n=381), age, HSCT, risk stratification, FLT3 mutation, and LDH elevation all had an impact on OS. However, when comparing those variables using multivariate analysis, age and FLT3 mutation lost their significance (p-value of 0.25 and 0.84, respectively).Complex karyotype and FLT3 mutations were more common in patients with elevated LDH. These patients tend to have higher WBC and peripheral blasts. Elevated LDH had a negative impact on patients' OS regardless of patients' risk classification.

OBJECTIVE: To identify distinct phenotypes of acute respiratory distress syndrome (ARDS) developing after hematopoietic cell transplantation (HCT), using routinely available clinical data at ICU admission. DESIGN: Multicenter retrospective cohort study using latent class analysis. SETTING: ICUs across three Mayo Clinic campuses (Minnesota, Florida, and Arizona). PATIENTS: A total of 166 adult patients who developed ARDS within 120 days following HCT (96 allogeneic, 70 autologous). INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Model selection was based on multiple metrics including Bayesian information criteria, entropy, and Vuong-Lo-Mendell-Rubin Likelihood Ratio testing. A two-class model optimally described the cohort. Class 1 (n = 81) was characterized by worse hypoxemia (P/F ratio 157 vs. 210, p = 0.002), higher Pco 2 (41 vs. 36 mm Hg, p < 0.001), and higher bilirubin (1.4 vs. 0.9 mg/dL, p < 0.001) compared with class 2 (n = 85). Both classes included a mix of transplant types, transcending a simple autologous/allogeneic dichotomy, although class 1 had more allogeneic recipients (70.4% vs. 45.9%, p = 0.001). Although time-from-transplant was not a class-defining variable, class 1 occurred later after transplant (30.0 vs. 11.9 d, p < 0.001) with higher frequency of idiopathic pneumonia syndrome (14.8% vs. 2.4%, p = 0.004). Class 2 had more frequent neutropenia (leukocytes 0.4 vs. 5.9 × 109, p < 0.001) and higher frequency of peri-engraftment respiratory distress syndrome (29.4% vs. 9.9%, p = 0.005). Outcomes were significantly worse for class 1 (90-d mortality: 72.8% vs. 48.2%, p = 0.001). An exploratory parsimonious model had good classification accuracy (0.90) using just six variables: leukocyte count, platelet count, bilirubin, Pco 2, body mass index, and temperature. CONCLUSIONS: ARDS after HCT comprises two distinct phenotypes with distinct clinical characteristics and outcomes. These phenotypes align with recognized post-HCT lung injury syndromes and may reflect different underlying biological processes. This framework provides a foundation for investigating targeted therapeutic approaches.

Abstract Front-line pharmaceutical interventions for treating acute graft-versus-host disease (GVHD) are not uniformly effective and have toxic side effects. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells with potent in vitro and in vivo immunosuppressive functions. Clinical translation of in vitro–generated MDSCs has been limited because of requirements for multiple, high infusion doses, the relatively low yield from peripheral blood–sourced MDSCs (PB-MDSCs), and inconsistent product quality. To circumvent these obstacles, we developed a methodology to generate MDSCs using human induced pluripotent stem cell (iPSC)–derived CD34+ cells. Compared with PB-MDSCs, iPSC-derived MDSCs (iMDSCs) shared similar morphology, phenotype, and suppressive function. We found that the CD14+ iMDSC subset possessed the highest suppressor function. In previous studies, we reported that MDSCs transferred into mice with GVHD lost suppressor function because of inflammasome activation and immature myeloid cell maturation. In striking contrast to human PB-MDSCs, we show herein that iMDSCs retained 95% of suppressor function in vitro despite exposure to lipopolysaccharide (LPS) plus adenosine triphosphate (ATP), which are stimuli that activate the inflammasome via danger-associated molecular patterns released during early posttransplant conditioning and GVHD-induced injury. In an in vivo xenogenic GVHD model with PB mononuclear cells, iMDSCs significantly increased recipient survival without loss of antileukemia effects. iMDSC RNA sequencing and gene knockdown studies revealed that the maintenance of the purine metabolizing enzyme, phosphoglycerate dehydrogenase, during LPS plus ATP treatment, was linked to iMDSC inflammasome resistance. Taken together, these findings provide a platform for translating in vitro–generated, off-the-shelf iMDSCs into the clinic for suppressing a spectrum of adverse immune responses, including GVHD.