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Abstract: Hematopoietic stem cell (HSC) transplantation with lentiviral vector (LVV)-transduced autologous cells has proven an effective therapeutic strategy for sickle cell disease (SCD). However, ex vivo culture or proliferative stress associated with in vivo reconstitution may amplify any underlying genetic risk of leukemia. We aimed to minimize culture-induced stress and reduce genomic damage during ex vivo culture and enhance stem cell fitness and reconstitution of SCD CD34+ cells transduced with BCL11A shmiR-encoding LVV. UM171, a pyrimidoindole derivative, can expand normal HSCs during in vitro culture and has been shown to be safe and effective using umbilical cord blood. We examined the effect of UM171 during ex vivo LVV transduction of SCD HSCs. Culture of SCD CD34+ HSCs with UM171 during transduction reduced DNA damage and reactive oxygen species, decreased apoptosis, and was associated with increased numbers of immunophenotypically defined long-term HSCs. UM171 increased the engraftment of LVV-transduced human HSCs in immunodeficient mice and barcode tracing revealed increased clonal diversity of engrafting cells. In competitive transplantation assays, analysis of bone marrow showed that cells transduced in the presence of UM171 consistently outcompeted those transduced under control conditions. In summary, exposure of SCD peripheral blood CD34+ cells to UM171 during LVV transduction enhances stem cell fitness. These findings suggest manufacturing of genetically modified HSCs in the presence of UM171 may improve efficacy, safety, and sustainability of gene therapy using ex vivo approaches. BCL11A shmiR-encoding LVV is in clinical trials to treat SCD (NCT03282656), UM171 is in clinical trials to culture umbilical cord blood (NCT02668315)., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Targeted therapeutics for high-risk cancers remain an unmet medical need. Here we report the results of a large-scale screen of over 11,000 molecules for their ability to inhibit the survival and growth in vitro of human leukemic cells from multiple sources including patient samples, de novo generated human leukemia models, and established human leukemic cell lines. The responses of cells from de novo models were most similar to those of patient samples, both of which showed striking differences from the cell-line responses. Analysis of differences in subtype-specific therapeutic vulnerabilities made possible by the scale of this screen enabled the identification of new specific modulators of apoptosis, while also highlighting the complex polypharmacology of anti-leukemic small molecules such as shikonin. These findings introduce a new platform for uncovering new therapeutic options for high-risk human leukemia, in addition to reinforcing the importance of the test sample choice for effective drug discovery., (© 2024. The Author(s).)

Multiple myeloma (MM) remains associated with a poor outcome, particularly in patients with advanced disease and high-risk (HR) cytogenetics. To date, the only curative treatment is allogeneic (allo) hematopoietic cell transplantation (HCT), but high incidences of graft versus host disease (GVHD), nonrelapse mortality (NRM) and disease progression remain important obstacles. Cord blood (CB) transplantation has been associated with low rates of relapse and chronic (c) GVHD, but its use has declined because of high incidences of infections, severe acute GVHD and high NRM. In other hematologic malignancies, UM171-expanded CB transplants have led to improved outcomes, allowing for the selection of smaller, better HLA-matched units. We aimed to investigate the safety and feasibility of single UM171-expanded single CB unit transplantation in frontline tandem auto/allo HCT for HR/ultra-HR MM patients. Newly diagnosed MM patients ≤ 65 years with an ISS stage II/III and del(17p), t(4;14), t(14;16), t(14;20), del(1p) or +1q, R-ISS 3, ≥ 2 cytogenetic abnormalities, or plasma cell leukemia without a sibling donor and availability of a 5-7/8 matched CB graft with ≥ 0.5 x 10 5 CD34+/kg and ≥ 1.5 x 10 7 TNCs/kg were eligible to this phase I/II prospective study (ClinicalTrials.gov NCT03441958). After induction and autologous HCT, patients received a reduced intensity conditioning regimen and were infused with 7-day UM171-expanded CD34+ cells, along with the lymphocytes contained in the CD34-negative fraction. The primary endpoints were feasibility of UM171 expansion, safety, kinetics of engraftment, incidences and maximum grades of acute and cGVHD at 1 and 2 years, assessment of measurable residual disease (MRD) and quality of life (QoL). Between 05/2018 and 11/2021, 20 patients were enrolled. One patient had an unsuccessful CB expansion with UM171, leaving 19 patients with a median age of 56 years. Median CD34+ cell dose infused after expansion was 4.62 x 10 6 /kg (range: 0.79 to 5.76). Median times to achieve absolute neutrophil counts of 0.1 and 0.5 x 10 9 /L were D+6 and D+10.5; median time to reach ≥ 20 x 10 9 /L platelets was D+36. Full donor chimerism was achieved in all cell lineages by D+120 in recipients of reduced intensity conditioning. Cumulative incidences of grade II-IV, grade III-IV acute GVHD and moderate/severe cGVHD at 12 months were 68.4% (95% CI: 46 to 90), 5.3% (95% CI: 0% to 16%), and 10.5% (95% CI: 0% to 25%), respectively. With a median follow-up of 2.9 years (range: 0.46 to 5.3), cumulative incidences of relapse, PFS, OS and NRM at 3 years were 36.8% (95% CI: 14 to 59), 47.4% (95% CI: 29 to 76), 68.4% (95% CI: 50 to 93) and 15.8% (95%CI: 0 to 33), respectively. Median time to complete immunosuppression discontinuation was D+238. No unexpected adverse events were observed. Only one of 7 patients alive at 2 years with negative MRD at transplant has relapsed. Non-relapsing patients had a QoL after transplant similar to the general population. UM171-expanded CB transplant in HR/ultra-HR myeloma patients is feasible and allows the use of single CB units with a low risk of cGVHD. Patients with negative pretransplant MRD might benefit most from a UM171-expanded CB transplant., (Copyright © 2024 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Abstract: The leukemic stem cell (LSC) score LSC-17 based on a stemness-related gene expression signature is an indicator of poor disease outcome in acute myeloid leukemia (AML). However, it is not known whether "niche anchoring" of LSC affects disease evolution. To address this issue, we conditionally inactivated the adhesion molecule JAM-C (Junctional Adhesion Molecule-C) expressed by hematopoietic stem cells (HSCs) and LSCs in an inducible mixed-lineage leukemia (iMLL)-AF9-driven AML mouse model. Deletion of Jam3 (encoding JAM-C) before induction of the leukemia-initiating iMLL-AF9 fusion resulted in a shift from long-term to short-term HSC expansion, without affecting disease initiation and progression. In vitro experiments showed that JAM-C controlled leukemic cell nesting irrespective of the bone marrow stromal cells used. RNA sequencing performed on leukemic HSCs isolated from diseased mice revealed that genes upregulated in Jam3-deficient animals belonged to activation protein-1 (AP-1) and tumor necrosis factor α (TNF-α)/NF-κB pathways. Human orthologs of dysregulated genes allowed to identify a score that was distinct from, and complementary to, the LSC-17 score. Substratification of patients with AML using LSC-17 and AP-1/TNF-α genes signature defined 4 groups with median survival ranging from <1 year to a median of "not reached" after 8 years. Finally, coculture experiments showed that AP-1 activation in leukemic cells was dependent on the nature of stromal cells. Altogether, our results identify the AP-1/TNF-α gene signature as a proxy of LSC anchoring in bone marrow niches, which improves the prognostic value of the LSC-17 score. This trial was registered at www.ClinicalTrials.gov as #NCT02320656., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Immunotherapy remains underexploited in acute myeloid leukemia (AML) compared to other hematological malignancies. Currently, gemtuzumab ozogamicin is the only therapeutic antibody approved for this disease. Here, to identify potential targets for immunotherapeutic intervention, we analyze the surface proteome of 100 genetically diverse primary human AML specimens for the identification of cell surface proteins and conduct single-cell transcriptome analyses on a subset of these specimens to assess antigen expression at the sub-population level. Through this comprehensive effort, we successfully identify numerous antigens and markers preferentially expressed by primitive AML cells. Many identified antigens are targeted by therapeutic antibodies currently under clinical evaluation for various cancer types, highlighting the potential therapeutic value of the approach. Importantly, this initiative uncovers AML heterogeneity at the surfaceome level, identifies several antigens and potential primitive cell markers characterizing AML subgroups, and positions immunotherapy as a promising approach to target AML subgroup specificities., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Arginine methylation is catalyzed by protein arginine methyltransferases (PRMTs) and is involved in various cellular processes, including cancer development. PRMT2 expression is increased in several cancer types although its role in acute myeloid leukemia (AML) remains unknown. Here, we investigate the role of PRMT2 in a cohort of patients with AML, PRMT2 knockout AML cell lines as well as a Prmt2 knockout mouse model. In patients, low PRMT2 expressors are enriched for inflammatory signatures, including the NF-κB pathway, and show inferior survival. In keeping with a role for PRMT2 in control of inflammatory signaling, bone marrow-derived macrophages from Prmt2 KO mice display increased pro-inflammatory cytokine signaling upon LPS treatment. In PRMT2-depleted AML cell lines, aberrant inflammatory signaling has been linked to overproduction of IL6, resulting from a deregulation of the NF-κB signaling pathway, therefore leading to hyperactivation of STAT3. Together, these findings identify PRMT2 as a key regulator of inflammation in AML., (© 2024. The Author(s).)

Precision gene editing in primary hematopoietic stem and progenitor cells (HSPCs) would facilitate both curative treatments for monogenic disorders as well as disease modelling. Precise efficiencies even with the CRISPR/Cas system, however, remain limited. Through an optimization of guide RNA delivery, donor design, and additives, we have now obtained mean precise editing efficiencies >90% on primary cord blood HSCPs with minimal toxicity and without observed off-target editing. The main protocol modifications needed to achieve such high efficiencies were the addition of the DNA-PK inhibitor AZD7648, and the inclusion of spacer-breaking silent mutations in the donor in addition to mutations disrupting the PAM sequence. Critically, editing was even across the progenitor hierarchy, did not substantially distort the hierarchy or affect lineage outputs in colony-forming cell assays or the frequency of high self-renewal potential long-term culture initiating cells. As modelling of many diseases requires heterozygosity, we also demonstrated that the overall editing and zygosity can be tuned by adding in defined mixtures of mutant and wild-type donors. With these optimizations, editing at near-perfect efficiency can now be accomplished directly in human HSPCs. This will open new avenues in both therapeutic strategies and disease modelling., Competing Interests: FC, JB, AS, HS, DK No competing interests declared, BL BL is currently the director of Stem Cell Engineering at ExcellThera. ExcellThera was not involved in the design, execution, or interpretation of the current study, GS GS is co-CEO of ExcellThera. ExcellThera was not involved in the design, execution, or interpretation of the current study, (© 2023, Cloarec-Ung et al.)

In a phenotypical screen of 56 acute myeloid leukemia (AML) patient samples and using a library of 10,000 compounds, we identified a hit with increased sensitivity toward SF3B1 -mutated and adverse risk AMLs. Through structure-activity relationship studies, this hit was optimized into a potent, specific, and nongenotoxic molecule called UM4118. We demonstrated that UM4118 acts as a copper ionophore that initiates a mitochondrial-based noncanonical form of cell death known as cuproptosis. CRISPR-Cas9 loss-of-function screen further revealed that iron-sulfur cluster (ISC) deficiency enhances copper-mediated cell death. Specifically, we found that loss of the mitochondrial ISC transporter ABCB7 is synthetic lethal to UM4118. ABCB7 is misspliced and down-regulated in SF3B1 -mutated leukemia, creating a vulnerability to copper ionophores. Accordingly, ABCB7 overexpression partially rescued SF3B1 -mutated cells to copper overload. Together, our work provides mechanistic insights that link ISC deficiency to cuproptosis, as exemplified by the high sensitivity of SF3B1 -mutated AMLs. We thus propose SF3B1 mutations as a biomarker for future copper ionophore-based therapies.

Abstract: Ex vivo expansion of hematopoietic stem cells (HSCs) is gaining importance for cell and gene therapy, and requires a shift from dormancy state to activation and cycling. However, abnormal or excessive HSC activation results in reduced self-renewal ability and increased propensity for myeloid-biased differentiation. We now report that activation of the E3 ligase complex CRL3KBTBD4 by UM171 not only induces epigenetic changes through CoREST1 degradation but also controls chromatin-bound master regulator of cell cycle entry and proliferative metabolism (MYC) levels to prevent excessive activation and maintain lympho-myeloid potential of expanded populations. Furthermore, reconstitution activity and multipotency of UM171-treated HSCs are specifically compromised when MYC levels are experimentally increased despite degradation of CoREST1., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Monosomy 5 and deletions of the chromosome 5q (-5/del(5q)) are recurrent events in de novo adult acute myeloid leukemia (AML), reaching up to 40% of cases in secondary AML. These chromosome anomalies are associated with TP53 mutations and with very poor prognosis. Using the large Leucegene genomic and transcriptomic dataset composed of 48 -5/del(5q) patient specimens and 367 control AML, we identified DELE1 - located in the common deleted region - as the most consistently downregulated gene in these leukemias. DELE1 encodes a mitochondrial protein recently characterized as the relay of mitochondrial stress to the cytosol through a newly defined OMA1-DELE1-HRI pathway which ultimately leads to the activation of ATF4, the master transcription factor of the integrated stress response. Here, we showed that the partial loss of DELE1 expression observed in -5/del(5q) patients was sufficient to significantly reduce the sensitivity to mitochondrial stress in AML cells. Overall, our results suggest that DELE1 haploinsufficiency could represent a new driver mechanism in -5/del(5q) AML., (© 2023. The Author(s).)

Abstract: Acute megakaryoblastic leukemia (AMKL) is a rare, developmentally restricted, and highly lethal cancer of early childhood. The paucity and hypocellularity (due to myelofibrosis) of primary patient samples hamper the discovery of cell- and genotype-specific treatments. AMKL is driven by mutually exclusive chimeric fusion oncogenes in two-thirds of the cases, with CBFA2T3::GLIS2 (CG2) and NUP98 fusions (NUP98r) representing the highest-fatality subgroups. We established CD34+ cord blood-derived CG2 models (n = 6) that sustain serial transplantation and recapitulate human leukemia regarding immunophenotype, leukemia-initiating cell frequencies, comutational landscape, and gene expression signature, with distinct upregulation of the prosurvival factor B-cell lymphoma 2 (BCL2). Cell membrane proteomic analyses highlighted CG2 surface markers preferentially expressed on leukemic cells compared with CD34+ cells (eg, NCAM1 and CD151). AMKL differentiation block in the mega-erythroid progenitor space was confirmed by single-cell profiling. Although CG2 cells were rather resistant to BCL2 genetic knockdown or selective pharmacological inhibition with venetoclax, they were vulnerable to strategies that target the megakaryocytic prosurvival factor BCL-XL (BCL2L1), including in vitro and in vivo treatment with BCL2/BCL-XL/BCL-W inhibitor navitoclax and DT2216, a selective BCL-XL proteolysis-targeting chimera degrader developed to limit thrombocytopenia in patients. NUP98r AMKL were also sensitive to BCL-XL inhibition but not the NUP98r monocytic leukemia, pointing to a lineage-specific dependency. Navitoclax or DT2216 treatment in combination with low-dose cytarabine further reduced leukemic burden in mice. This work extends the cellular and molecular diversity set of human AMKL models and uncovers BCL-XL as a therapeutic vulnerability in CG2 and NUP98r AMKL., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Leukemia stem cells (LSCs) share numerous features with healthy hematopoietic stem cells (HSCs). G-protein coupled receptor family C group 5 member C (GPRC5C) is a regulator of HSC dormancy. However, GPRC5C functionality in acute myeloid leukemia (AML) is yet to be determined. Within patient AML cohorts, high GPRC5C levels correlated with poorer survival. Ectopic Gprc5c expression increased AML aggression through the activation of NF-κB, which resulted in an altered metabolic state with increased levels of intracellular branched-chain amino acids (BCAAs). This onco-metabolic profile was reversed upon loss of Gprc5c, which also abrogated the leukemia-initiating potential. Targeting the BCAA transporter SLC7A5 with JPH203 inhibited oxidative phosphorylation and elicited strong antileukemia effects, specifically in mouse and patient AML samples while sparing healthy bone marrow cells. This antileukemia effect was strengthened in the presence of venetoclax and azacitidine. Our results indicate that the GPRC5C-NF-κB-SLC7A5-BCAAs axis is a therapeutic target that can compromise leukemia stem cell function in AML., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Cord blood (CB) transplantation is hampered by low cell dose and high nonrelapse mortality (NRM). A phase 1-2 trial of UM171-expanded CB transplants demonstrated safety and favorable preliminary efficacy. The aim of the current analysis was to retrospectively compare results of the phase 1-2 trial with those after unmanipulated CB and matched-unrelated donor (MUD) transplants. Data from recipients of CB and MUD transplants were obtained from the Center for International Blood and Marrow Transplant Research (CIBMTR) database. Patients were directly matched for the number of previous allogeneic hematopoietic stem cell transplants (alloHCT), disease and refined Disease Risk Index. Patients were further matched by propensity score for age, comorbidity index, and performance status. Primary end points included NRM, progression-free survival (PFS), overall survival (OS), and graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) at 1 and 2 years after alloHCT. Overall, 137 patients from CIBMTR (67 CB, 70 MUD) and 22 with UM171-expanded CB were included. NRM at 1 and 2 years was lower, PFS and GRFS at 2 years and OS at 1 year were improved for UM171-expanded CBs compared with CB controls. Compared with MUD controls, UM171 recipients had lower 1- and 2-year NRM, higher 2-year PFS, and higher 1- and 2-year GRFS. Furthermore, UM171-expanded CB recipients experienced less grades 3-4 acute GVHD and chronic GVHD compared with MUD graft recipients. Compared with real-world evidence with CB and MUD alloHCT, this study suggests that UM171-expanded CB recipients may benefit from lower NRM and higher GRFS. This trial was registered at www.clinicaltrials.gov as #NCT02668315., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The high degree of complexity of the product-review process and differences in procedures between organizations have resulted in a need for best practices and an overall product-review process to create efficiencies for health care decision makers. In an effort to streamline product-review concepts, this article outlines the different components of the review process, including clinical and economic review, formulary placement determination, and evaluation of alternatives within a drug class. The article also details opportunities for the near future, as technology continues to advance and alignment between medical and pharmacy benefits is desired. DISCLOSURES: Drs Linnerooth, Penley, Ha, and Craven report employment with Xcenda, which provided funding for the manuscript. Drs Sauvageau and Hydery report employment Xcenda, which provided funding for the manuscript, and stock holdings with AmerisourceBergen. Dr Feeney reports support for attending meetings and/or travel provided by Highmark, Inc. Dr Thomas reports receipt of consulting fees from ActiveRADAR, board member roles with ActiveRADAR and RoundtableRx, an adjunct professor role with the University of Minnesota, and stock options and pensions with Eli Lilly and Aetna/CVS. Dr Watkins reports payment or honoraria from ISPOR and for articles written for Value and Outcomes Spotlight, and support for attending meetings and/or travel by AMCP.

With the advent of new cellular and targeted therapies, treatment options for relapsed and refractory (r/R) lymphomas have multiplied, and the optimal approach offering the best outcomes remains a matter of passionate debate. High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is still considered a treatment option for patients with chemosensitive lymphoma when cure is the expected goal. The myeloablative conditioning regimen preceding the stem cell infusion is considered the effective component of this approach. Carmustine (BCNU)-based preparative regimens, such as BEAM and BEAC, are considered the standard of care and have shown efficacy and low nonrelapse mortality (NRM). Comparative studies between conditioning regimens have failed to identify a better option. After a BCNU drug shortage in Canada followed by a steep increase in price, we elected to substitute BCNU for bendamustine (benda) in the preparative regimen. The purpose of this substitution was to improve response while preserving safety and controlling costs. From May 2015 to May 2018, a total of 131 consecutive lymphoma patients received benda-EAM conditioning. These patients were compared with 96 consecutive patients who received BCNU-based conditioning from January 2012 to May 2015. Apart from conditioning, supportive care measures were the same in the 2 groups. Patients receiving benda were older (55.7 years versus 51.1 years; P = .002). The development of grade ≥3 mucositis was more frequent with benda conditioning (39.5% versus 7.8%; P < .001) leading to a greater requirement for parenteral nutrition (48.9% versus 21.9%; P < .001). A transient creatinine increase >1.5 times the upper limit of normal (15.3% versus 4.2%; P < .008) and intensive care unit admission (6.9% versus 1.1%; P < .029) were more frequent with benda; however, there were no between-group differences in cardiac, pulmonary, or liver toxicity and NRM. With a median follow-up of 48 months for the benda group and 60 months for the BCNU group, benda was associated with significantly better progression-free survival (71% versus 61%; P = .040; hazard ratio [HR], 1.6; 95% confidence interval [CI], 1.0 to 2.7) and overall survival (86% vs 71%; P = .0066; HR, 2.6; 95% CI, 1.3 to 5.4) compared with BCNU-based conditioning regimens. While novel therapies emerge, our study demonstrates that benda-EAM is safe and effective and should be considered a valid alternative to BCNU conditioning to improve outcomes of patients with chemosensitive r/R lymphomas undergoing ASCT., (Copyright © 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Allogeneic hematopoietic cell transplantation (HCT) has curative potential in myeloma but remains hampered by high rates of relapse and chronic graft-versus-host disease (GVHD). We hypothesized that bortezomib (BTZ) as maintenance therapy after allo HCT could not only decrease the incidence of relapse but also the incidence and severity of chronic GVHD. The primary endpoint of this study was to determine whether BTZ maintenance decreases the incidence and severity of chronic GVHD using National Institutes of Health (NIH) criteria. The secondary endpoints were to determine the immunosuppression burden, organ involvement and survival (overall survival, progression-free survival) in patients either receiving or not receiving BTZ. In this retrospective study, we compared the outcome of 46 myeloma patients who received BTZ after upfront tandem auto-allo HCT between 2008 and 2020 to 61 patients without maintenance. We explored the impact of BTZ maintenance on incidence and severity of chronic GVHD using the 2014 NIH criteria. At 2 years, incidences of overall (61.2% versus 83.6%; P = .001), and moderate/severe chronic GVHD (44.5% versus 77.0%; P = .001) were significantly lower in BTZ recipients who had less mouth (43% versus 67%; P = .018) and eyes (9% versus 41%; P = .001) involvement at initial diagnosis. We report a lower use of systemic steroids (45.1% versus 76.4%; P < .001), mycophenolate mofetil (15.5% versus 28.2%; P = .031) and tacrolimus (34.5% versus 70.6%; P < .001) in BTZ recipients. Probability of being alive and off systemic immunosuppressants at 3 years was 77% in BTZ recipients and 56% in controls (P = .046). To date, there is no difference in survival between both groups. In summary, BTZ maintenance improved incidence and severity of chronic GVHD and should be considered as a valid option in myeloma patients receiving upfront tandem auto-allo HCT., Competing Interests: Conflict of interest statement There are no conflicts of interest to report., (Copyright © 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

High-mobility group AT-hook 2 (HMGA2) is a nonhistone chromatin-binding protein that is normally expressed in stem cells of various tissues and aberrantly detected in several tumor types. We recently observed that one-fourth of human acute myeloid leukemia (AML) specimens express HMGA2, which associates with a very poor prognosis. We present results indicating that HMGA2+ AMLs share a distinct transcriptional signature representing an immature phenotype. Using single-cell analyses, we showed that HMGA2 is expressed in CD34+ subsets of stem cells and early progenitors, whether normal or derived from AML specimens. Of interest, we found that one of the strongest gene expression signatures associated with HMGA2 in AML is the upregulation of G2/M checkpoint genes. Whole-genome CRISPR/Cas9 screening in HMGA2 overexpressing cells further revealed a synthetic lethal interaction with several G2/M checkpoint genes. Accordingly, small molecules that target G2/M proteins were preferentially active in vitro and in vivo on HMGA2+ AML specimens. Together, our findings suggest that HMGA2 is a key functional determinant in AML and is associated with stem cell features, G2/M status, and related drug sensitivity., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The purpose of this retrospective study was to study the correlation between donor age (DA) and non-relapse mortality (NRM) and relapse incidence (RI) among patients treated with allogeneic hematopoietic cell transplantation (aHCT) for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) in a single Canadian center. Data from 125 consecutive patients transplanted with a matched related or unrelated donor between 2015 and 2020 were analyzed using multivariable models. After a median follow-up of 2.8 years, the cumulative incidences of NRM and relapse were 19% and 35% at 5 years. Despite being independently associated with NRM and relapse-free survival (RFS), DA was not associated with RI. The independent determinants of NRM in addition to DA were patient age and hematopoietic cell transplantation comorbidity index (HCT-CI), independently of donor kinship. The effect of DA on NRM was found to be significantly increased over the age of 50 years. DA was not associated with incidence of acute graft-versus-host disease (aGVHD) but showed an association with the occurrence of chronic GVHD (cGVHD). In conclusion, younger donors should be favored to limit NRM and increase RFS in HLA-matched aHCT. The etiological mechanisms behind the association of DA with higher NRM remain to be elucidated.

Cord blood (CB) stem cell transplantation offers a greater tolerance to HLA mismatches compared to adult-derived stem cell transplants (i.e., bone marrow or peripheral blood stem cells). Indeed, 4/6 or 5/8 HLA-matched CB transplantations are regularly performed for patients lacking a matched unrelated donor. Unfortunately, most banked CB units contain a stem cell dose that is too small to treat adult patients, resulting in only 4% to 5% of available CB units offering an adequate cell dose for prompt engraftment for adult patients. Ex vivo stem cell expansion appears to be an attractive strategy to circumvent this cell dose issue, while also enabling the selection of better HLA-matched CB units. In this study, we retrospectively performed HLA matching simulations to assess how the minimal cell content requirements associated with UM171 CB expansion may improve usability of existing CB unit inventories and donor availability for patients of different races and ethnicities. We analyzed a dataset of 58,971 adults for whom a donor search was initiated through the National Marrow Donor Program Be The Match registry against 142,942 CB units from major U.S. public CB banks listed on the Be The Match registry. Our results show that by enabling selection of smaller CB units, UM171-expanded CB transplantation increases donor availability from 72% to 84% for all patients compared to single unmanipulated CB transplantation. Furthermore, the low cell dose criteria for UM171-expanded CB also increases donor availability compared to double CB transplantation, while enabling better HLA matching between donor and recipient. UM171 expanded CB appears particularly beneficial for racial and ethnic minority patients as CB availability increases from 53% to 78% for African Americans, from 66% to 85% for Hispanics, and from 68% to 84% for Asians and Pacific Islanders, compared to single unmanipulated CB transplantation. In addition, UM171 expansion dramatically improves usability of CB units currently in inventories, as only 4.3% and 0.6% of banked CBs have sufficient cell doses for a 70 kg and 100 kg patient, respectively. UM171 raises this proportion to 53.8% and 20.2%, respectively, making CB banks potentially more cost effective. In conclusion, UM171 expansion allows the use of smaller CB units while also improving access to transplantation for racial and ethnic minorities., (Copyright © 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Bone marrow haematopoietic stem cells (HSCs) are vital for lifelong maintenance of healthy haematopoiesis. In inbred mice housed in gnotobiotic facilities, the top of the haematopoietic hierarchy is occupied by dormant HSCs, which reversibly exit quiescence during stress. Whether HSC dormancy exists in humans remains debatable. Here, using single-cell RNA sequencing, we show a continuous landscape of highly purified human bone marrow HSCs displaying varying degrees of dormancy. We identify the orphan receptor GPRC5C, which enriches for dormant human HSCs. GPRC5C is also essential for HSC function, as demonstrated by genetic loss- and gain-of-function analyses. Through structural modelling and biochemical assays, we show that hyaluronic acid, a bone marrow extracellular matrix component, preserves dormancy through GPRC5C. We identify the hyaluronic acid-GPRC5C signalling axis controlling the state of dormancy in mouse and human HSCs., (© 2022. The Author(s).)

T-cell acute lymphoblastic leukemia (T-ALL) is commonly driven by activating mutations in NOTCH1 that facilitate glutamine oxidation. Here we identify oxidative phosphorylation (OxPhos) as a critical pathway for leukemia cell survival and demonstrate a direct relationship between NOTCH1, elevated OxPhos gene expression, and acquired chemoresistance in pre-leukemic and leukemic models. Disrupting OxPhos with IACS-010759, an inhibitor of mitochondrial complex I, causes potent growth inhibition through induction of metabolic shut-down and redox imbalance in NOTCH1-mutated and less so in NOTCH1-wt T-ALL cells. Mechanistically, inhibition of OxPhos induces a metabolic reprogramming into glutaminolysis. We show that pharmacological blockade of OxPhos combined with inducible knock-down of glutaminase, the key glutamine enzyme, confers synthetic lethality in mice harboring NOTCH1-mutated T-ALL. We leverage on this synthetic lethal interaction to demonstrate that IACS-010759 in combination with chemotherapy containing L-asparaginase, an enzyme that uncovers the glutamine dependency of leukemic cells, causes reduced glutaminolysis and profound tumor reduction in pre-clinical models of human T-ALL. In summary, this metabolic dependency of T-ALL on OxPhos provides a rational therapeutic target., (© 2022. The Author(s).)

The heterogeneous response of acute myeloid leukemia (AML) to current anti-leukemic therapies is only partially explained by mutational heterogeneity. We previously identified GPR56 as a surface marker associated with poor outcome across genetic groups, which characterizes two leukemia stem cell (LSC)-enriched compartments with different self-renewal capacities. How these compartments self-renew remained unclear. Here, we show that GPR56 + LSC compartments are promoted in a complex network involving epithelial-to-mesenchymal transition (EMT) regulators besides Rho, Wnt, and Hedgehog (Hh) signaling. Unexpectedly, Wnt pathway inhibition increased the more immature, slowly cycling GPR56 + CD34 + fraction and Hh/EMT gene expression, while Wnt activation caused opposite effects. Our data suggest that the crucial role of GPR56 lies in its ability to co-activate these opposing signals, thus ensuring the constant supply of both LSC subsets. We show that CDK7 inhibitors suppress both LSC-enriched subsets in vivo and synergize with the Bcl-2 inhibitor venetoclax. Our data establish reciprocal transition between LSC compartments as a novel concept underlying the poor outcome in GPR56 high AML and propose combined CDK7 and Bcl-2 inhibition as LSC-directed therapy in this disease., (©2022 The Authors. Published under the terms of the CC BY 4.0 license.)

Despite high cure rates with frontline therapy for Hodgkin lymphoma (HL), approximately 30% of patients will relapse or develop primary refractory disease (R/r). Autologous hematopoietic stem cell transplantation (autoHSCT) is the standard of care for R/r disease, and allogeneic HSCT (alloHSCT) is a curative option for patients in second relapse. Novel agents are being incorporated for the treatment of R/r HL, such that the optimal timing of transplantation is currently being challenged. In this rapidly evolving field, we sought to offer a Canadian perspective on the optreatment of R/r HL and demonstrate the role and effectiveness of both autoHSCT and alloHSCT for the treatment of R/r HL. This single-center retrospective study examined outcomes in 89 consecutive patients with R/r HL treated with autoHSCT between January 2007 and December 2019. A total of 17 patients underwent alloHSCT either as a tandem auto-allo approach or as salvage therapy. With a median follow-up of 5.0 years, the estimated 5-year PFS and OS for patients undergoing autoHSCT were 57.5% (95% confidence interval [CI], 45.2% to 68.0%) and 81.3% (95% CI, 70.0% to 88.8%), respectively. Corresponding values for patients who underwent alloHSCT were 76.5% (95% CI, 48.8% to 90.4%) and 82.4% (95% CI, 54.7% to 93.9%). Nonrelapse mortality at 0% at 100 days and 9.4% at 5 years post-autoHSCT and 0% and 5.9%, respectively, post-alloHSCT. The cumulative incidence of acute graft-versus-host disease (GVHD) at day +100 was 35.3% (95% CI, 17.7% to 62.3%), and that of chronic GVHD at 1 year was 23.5% (95% CI, 6.9% to 45.8%). Both autoHSCT and alloHSCT provide robust and prolonged disease control New agents should be used as a bridge to improve the curative potential of these definitive cellular therapies., (Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Despite novel drugs and autologous HCT, MM remains incurable, with short survival in patients with poor biological characteristics. Allo HCT may be curative in some patients but is hampered by high rates of toxicity and relapse. We hypothesized that bortezomib (BTZ), with its anti-myeloma and immunologic properties, could improve PFS and cGVHD after allo HCT in newly diagnosed MM patients. In this prospective phase II study, we included 39 young (≤50 years) and high-risk patients who received a tandem auto-allo HCT followed by BTZ. Patients had prospective minimal residual disease (MRD) evaluations using Next-Generation Flow cytometry prior to allo HCT, prior BTZ and every 3 months for 2 years. With a median follow-up of 48 months, we report PFS and OS at 5 years of 41% and 80%, with a non-relapse mortality of 12%. Incidences of grade II-IV aGVHD at 12 months and moderate/severe cGVHD at 2 years were 26% and 57%. In a multivariate analysis model including cytogenetics, ISS and MRD status, MRD positivity prior to allo HCT (HR 3.75, p = 0.037), prior BTZ (HR 11.3, p = 0.018) and 3 months post-BTZ initiation (HR 9.7, p = 0.001) was highly predictive of progression. Peritransplant MRD assessment thus strongly predicts disease progression., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Cholesterol homeostasis has been proposed as one mechanism contributing to chemoresistance in AML and hence, inclusion of statins in therapeutic regimens as part of clinical trials in AML has shown encouraging results. Chemical screening of primary human AML specimens by our group led to the identification of lipophilic statins as potent inhibitors of AMLs from a wide range of cytogenetic groups. Genetic screening to identify modulators of the statin response uncovered the role of protein geranylgeranylation and of RAB proteins, coordinating various aspect of vesicular trafficking, in mediating the effects of statins on AML cell viability. We further show that statins can inhibit vesicle-mediated transport in primary human specimens, and that statins sensitive samples show expression signatures reminiscent of enhanced vesicular trafficking. Overall, this study sheds light into the mechanism of action of statins in AML and identifies a novel vulnerability for cytogenetically diverse AML., (© 2022 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Hematopoietic stem cells (HSCs) sustain blood cell homeostasis throughout life and can regenerate all blood lineages after transplantation. Despite this clear functional definition, highly enriched isolation of human HSCs can currently only be achieved through combinatorial assessment of multiple surface antigens. Although several transgenic HSC reporter mouse strains have been described, no analogous approach to prospectively isolate human HSCs has been reported. To identify genes with the most selective expression in human HSCs, we profiled population and single-cell transcriptomes of unexpanded and ex vivo cultured cord blood-derived hematopoietic stem and progenitor cells as well as peripheral blood, adult bone marrow, and fetal liver. On the basis of these analyses, we propose the master transcription factor HLF (hepatic leukemia factor) as one of the most specific HSC marker genes. To directly track its expression in human hematopoietic cells, we developed a genomic HLF reporter strategy, capable of selectively labeling the most immature blood cells on the basis of a single engineered parameter. Most importantly, HLF-expressing cells comprise all stem cell activity in culture and in vivo during serial transplantation. Taken together, these results experimentally establish HLF as a defining gene of the human HSC state and outline a new approach to continuously mark these cells with high fidelity., (© 2021 by The American Society of Hematology.)

Background: This study aims to identify a novel potential use for web portals in health care and health research: their adoption for the purposes of rapidly sharing health research findings with clinicians, scientists, and patients. In the era of precision medicine and learning health systems, the translation of research findings into targeted therapies depends on the availability of big data and emerging research results. Web portals may work to promote the availability of novel research, working in tandem with traditional scientific publications and conference proceedings., Objective: This study aims to assess the potential use of web portals, which facilitate the sharing of health research findings among researchers, clinicians, patients, and the public. It also summarizes the potential legal, ethical, and policy implications associated with such tools for public use and in the management of patient care for complex diseases., Methods: This study broadly adopts the methods for scoping literature reviews outlined by Arskey and O'Malley in 2005. Raised by the integration of web portals into patient care for complex diseases, we systematically searched 3 databases, PubMed, Scopus, and WestLaw Next, for sources describing web portals for sharing health research findings among clinicians, researchers, and patients and their associated legal, ethical, and policy challenges. Of the 719 candidate source citations, 22 were retained for the review., Results: We found varied and inconsistent treatment of web portals for sharing health research findings among clinicians, researchers, and patients. Although the literature supports the view that portals of this kind are potentially highly promising, they remain novel and are not yet widely adopted. We also found a wide range of discussions on the legal, ethical, and policy issues related to the use of web portals to share research data., Conclusions: We identified 5 important legal and ethical challenges: privacy and confidentiality, patient health literacy, equity, training, and decision-making. We contend that each of these has meaningful implications for the increased integration of web portals into clinical care., (©Michael Lang, Sébastien Lemieux, Josée Hébert, Guy Sauvageau, Ma'n H Zawati. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 11.11.2021.)

BACKGROUND: In 2014, qualified health plans sold in the Affordable Care Act (ACA) marketplaces were accused of providing drug coverage that was too restrictive and costly. After the change in administration in 2016, efforts to repeal portions of the ACA led to increases in premiums, decreases in enrollment, and overall uncertainty. OBJECTIVE: To examine how the number of formulary tiers and medication cost sharing, as well as transparency around these aspects, in qualified bronze and silver health plans in California, Florida, and Illinois changed from 2014 to 2018. METHODS: A search of all bronze and silver qualified health plans in California, Florida, and Illinois was performed in 2014 and in 2018 through the marketplace and issuer websites. RESULTS: From 2014 to 2018, the total number of bronze and silver qualified health plans offered in California, Florida, and Illinois remained relatively stable (36 to 35, 123 to 122, and 60 to 74, respectively). Over the same time period, the median number of formulary tiers remained constant for California and Florida (four and five) and increased from five to seven for Illinois. Of note, most Illinois plans shifted from a formulary with five or fewer tiers (92% of plans) to seven tiers (73% of plans) between 2014 and 2018. There was also an increase in the use of coinsurance instead of copay for each of the four following formulary tiers: generic (19% to 27% of plans), preferred brand (21% to 38%), nonpreferred brand (33% to 52%), and specialty (76% to 91%). Additionally, there was an increase in the median coinsurance rates for each of the aforementioned tiers: 0% to 25%, 0% to 35%, 30% to 40%, and 30% to 40%, respectively. The proportion of plans that provided their formularies on the marketplace website increased from 82% to 97% from 2014 to 2018, with the increase mostly driven by California plans (0% to 80%). There was a small increase in the proportion of plans that reported medication cost sharing through the medical benefit from 2014 (19%) to 2018 (25%). CONCLUSIONS: Between 2014 and 2018, qualified health plans increased their use of formularies with greater numbers of tiers, the use of coinsurance for each tier, and higher coinsurance rates. Availability of formularies on marketplace websites increased, but cost sharing transparency for medications covered by the medical benefit could greatly improve. DISCLOSURES: No funding supported this study. Hung reports past employment by Blue Cross Blue Shield Association, CVS Health, and a grant from PhRMA outside of the submitted work. She was an intern at the Biotechnology Industry Organization when this work began. Sauvageau has no disclosures. This work was presented as a poster at the AMCP 2018 Managed Care & Specialty Pharmacy Annual Meeting; April 23-26, 2018; Boston, MA.

Acute myeloid leukemia (AML) underlies the uncontrolled accumulation of immature myeloid blasts. Several cytogenetic abnormalities have been associated with AML. Among these is the NUP98-HOXA9 (NA9) translocation that fuses the Phe-Gly repeats of nucleoporin NUP98 to the homeodomain of the transcription factor HOXA9. The mechanisms enabling NA9-induced leukemia are poorly understood. Here, we conducted a genetic screen in Drosophila for modifiers of NA9. The screen uncovered 29 complementation groups, including genes with mammalian homologs known to impinge on NA9 activity. Markedly, the modifiers encompassed a diversity of functional categories, suggesting that NA9 perturbs multiple intracellular events. Unexpectedly, we discovered that NA9 promotes cell fate transdetermination and that this phenomenon is greatly influenced by NA9 modifiers involved in epigenetic regulation. Together, our work reveals a network of genes functionally connected to NA9 that not only provides insights into its mechanism of action, but also represents potential therapeutic targets., Competing Interests: The authors have declared that no competing interests exist.

Background: Acute myeloid leukemia (AML) stem cells (LSCs) are capable of surviving current standard chemotherapy and are the likely source of deadly, relapsed disease. While stem cell transplant serves as proof-of-principle that AML LSCs can be eliminated by the immune system, the translation of existing immunotherapies to AML has been met with limited success. Consequently, understanding and exploiting the unique immune-evasive mechanisms of AML LSCs is critical., Methods: Analysis of stem cell datasets and primary patient samples revealed CD200 as a putative stem cell-specific immune checkpoint overexpressed in AML LSCs. Isogenic cell line models of CD200 expression were employed to characterize the interaction of CD200 + AML with various immune cell subsets both in vitro and in peripheral blood mononuclear cell (PBMC)-humanized mouse models. CyTOF and RNA-sequencing were performed on humanized mice to identify novel mechanisms of CD200-mediated immunosuppression. To clinically translate these findings, we developed a fully humanized CD200 antibody (IgG1) that removed the immunosuppressive signal by blocking interaction with the CD200 receptor while also inducing a potent Fc-mediated response. Therapeutic efficacy of the CD200 antibody was evaluated using both humanized mice and patient-derived xenograft models., Results: Our results demonstrate that CD200 is selectively overexpressed in AML LSCs and is broadly immunosuppressive by impairing cytokine secretion in both innate and adaptive immune cell subsets. In a PBMC-humanized mouse model, CD200 + leukemia progressed rapidly, escaping elimination by T cells, compared with CD200 - AML. T cells from mice with CD200 + AML were characterized by an abundance of metabolically quiescent CD8 + central and effector memory cells. Mechanistically, CD200 expression on AML cells significantly impaired OXPHOS metabolic activity in T cells from healthy donors. Importantly, CD200 antibody therapy could eliminate disease in the presence of graft-versus-leukemia in immune competent mice and could significantly improve the efficacy of low-intensity azacitidine/venetoclax chemotherapy in immunodeficient hosts., Conclusions: Overexpression of CD200 is a stem cell-specific marker that contributes to immunosuppression in AML by impairing effector cell metabolism and function. CD200 antibody therapy is capable of simultaneously reducing CD200-mediated suppression while also engaging macrophage activity. This study lays the groundwork for CD200-targeted therapeutic strategies to eliminate LSCs and prevent AML relapse., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

While oncogenes promote tumorigenesis, they also induce deleterious cellular stresses, such as apoptosis, that cancer cells must combat by coopting adaptive responses. Whether tumor suppressor gene haploinsufficiency leads to such phenomena and their mechanistic basis is unclear. Here, we demonstrate that elevated levels of the anti-apoptotic factor, CASP8 and FADD-like apoptosis regulator (CFLAR), promotes apoptosis evasion in acute myeloid leukemia (AML) cells haploinsufficient for the cut-like homeobox 1 (CUX1) transcription factor, whose loss is associated with dismal clinical prognosis. Genome-wide CRISPR/Cas9 screening identifies CFLAR as a selective, acquired vulnerability in CUX1-deficient AML, which can be mimicked therapeutically using inhibitor of apoptosis (IAP) antagonists in murine and human AML cells. Mechanistically, CUX1 deficiency directly alleviates CUX1 repression of the CFLAR promoter to drive CFLAR expression and leukemia survival. These data establish how haploinsufficiency of a tumor suppressor is sufficient to induce advantageous anti-apoptosis cell survival pathways and concurrently nominate CFLAR as potential therapeutic target in these poor-prognosis leukemias.

Acute myeloid leukemia (AML) has not benefited from innovative immunotherapies, mainly because of the lack of actionable immune targets. Using an original proteogenomic approach, we analyzed the major histocompatibility complex class I (MHC class I)-associated immunopeptidome of 19 primary AML samples and identified 58 tumor-specific antigens (TSAs). These TSAs bore no mutations and derived mainly (86%) from supposedly non-coding genomic regions. Two AML-specific aberrations were instrumental in the biogenesis of TSAs, intron retention, and epigenetic changes. Indeed, 48% of TSAs resulted from intron retention and translation, and their RNA expression correlated with mutations of epigenetic modifiers (e.g., DNMT3A). AML TSA-coding transcripts were highly shared among patients and were expressed in both blasts and leukemic stem cells. In AML patients, the predicted number of TSAs correlated with spontaneous expansion of cognate T cell receptor clonotypes, accumulation of activated cytotoxic T cells, immunoediting, and improved survival. These TSAs represent attractive targets for AML immunotherapy., Competing Interests: Declaration of interests G.E., M.-P.H., S.L., P.T., and C.P. are named inventors on a patent application filed by Université de Montréal and covering antigens described in this article., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Zinc finger (ZnF) proteins represent one of the largest families of human proteins, although most remain uncharacterized. Given that numerous ZnF proteins are able to interact with DNA and poly(ADP ribose), there is growing interest in understanding their mechanism of action in the maintenance of genome integrity. We now report that the ZnF protein E4F transcription factor 1 (E4F1) is an actor in DNA repair. Indeed, E4F1 is rapidly recruited, in a poly(ADP ribose) polymerase (PARP)-dependent manner, to DNA breaks and promotes ATR/CHK1 signaling, DNA-end resection, and subsequent homologous recombination. Moreover, we identify E4F1 as a regulator of the ATP-dependent chromatin remodeling SWI/SNF complex in DNA repair. E4F1 binds to the catalytic subunit BRG1/SMARCA4 and together with PARP-1 mediates its recruitment to DNA lesions. We also report that a proportion of human breast cancers show amplification and overexpression of E4F1 or BRG1 that are mutually exclusive with BRCA1 / 2 alterations. Together, these results reveal a function of E4F1 in the DNA damage response that orchestrates proper signaling and repair of double-strand breaks and document a molecular mechanism for its essential role in maintaining genome integrity and cell survival., Competing Interests: The authors declare no competing interest.

Human hematopoietic stem cells (HSCs) exhibit attrition of their self-renewal capacity when cultured ex vivo, a process that is partially reversed upon treatment with epigenetic modifiers, most notably inhibitors of histone deacetylases (HDACs) or lysine-specific demethylase LSD1. A recent study showed that the human HSC self-renewal agonist UM171 modulates the CoREST complex, leading to LSD1 degradation, whose inhibition mimics the activity of UM171. The mechanism underlying the UM171-mediated loss of CoREST function remains undetermined. We now report that UM171 potentiates the activity of a CULLIN3-E3 ubiquitin ligase (CRL3) complex whose target specificity is dictated by the poorly characterized Kelch/BTB domain protein KBTBD4. CRL3 KBTBD4 targets components of the LSD1/RCOR1 corepressor complex for proteasomal degradation, hence re-establishing H3K4me2 and H3K27ac epigenetic marks, which are rapidly decreased upon ex vivo culture of human HSCs., Competing Interests: Declaration of interests Except for G.S., the authors declare no competing interests. G.S. is founder and CEO of ExCellThera, a small biotech that owns an exclusive license to UM171., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Rapid T cell reconstitution following hematopoietic stem cell transplantation (HSCT) is essential for protection against infections and has been associated with lower incidence of chronic graft-versus-host disease (cGVHD), relapse, and transplant-related mortality (TRM). While cord blood (CB) transplants are associated with lower rates of cGVHD and relapse, their low stem cell content results in slower immune reconstitution and higher risk of graft failure, severe infections, and TRM. Recently, results of a phase I/II trial revealed that single UM171-expanded CB transplant allowed the use of smaller CB units without compromising engraftment (www.clinicaltrials.gov, NCT02668315). We assessed T cell reconstitution in patients who underwent transplantation with UM171-expanded CB grafts and retrospectively compared it to that of patients receiving unmanipulated CB transplants. While median T cell dose infused was at least 2 to 3 times lower than that of unmanipulated CB, numbers and phenotype of T cells at 3, 6, and 12 months post-transplant were similar between the 2 cohorts. T cell receptor sequencing analyses revealed that UM171 patients had greater T cell diversity and higher numbers of clonotypes at 12 months post-transplant. This was associated with higher counts of naive T cells and recent thymic emigrants, suggesting active thymopoiesis and correlating with the demonstration that UM171 expands common lymphoid progenitors in vitro. UM171 patients also showed rapid virus-specific T cell reactivity and significantly reduced incidence of severe infections. These results suggest that UM171 patients benefit from rapid T cell reconstitution, which likely contributes to the absence of moderate/severe cGVHD, infection-related mortality, and late TRM observed in this cohort., (Copyright © 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Background: Long-term survival in patients progressing after tandem autologous-allogeneic stem cell transplant (SCT) has been reported, suggesting a persistent graft-vs-myeloma (GvM) effect even after post-transplant progression., Methods: In order to confirm this observation, we updated the results of our previously published cohort of 92 newly diagnosed myeloma patients who received tandem transplant and compared them with 81 contemporary patients who received autologous transplant only., Results: With a median follow-up of 13.1 and 10.2 years, respectively, median overall survival (OS) in the tandem group has not been reached, compared with 6.1 years after auto-SCT (P ≤ .001). Disease progression occurred less frequently after tandem transplant, with an estimated 10-year cumulative incidence of 49% vs 76% (P ≤ .001). Cumulative incidence of extensive chronic graft-vs-host disease (cGVHD) was high at 83%, with modest benefits on OS (60% vs 49%, P = .550) but sharp improvement of progression-free survival (PFS; 55% vs 10%, P = .002) at 10 years associated with development of cGVHD. After first progression, median OS was 5.8 years in tandem and 5.2 years in the auto-group (P = .062); median PFS was also similar., Conclusion: Despite confirmation of better outcomes after upfront tandem transplant, our data do not support persistence of a strong, clinically significant graft-vs-myeloma effect after first progression, emphasizing the need to better characterize the GvM effect., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

RUNX1 is mutated in ∼10% of adult acute myeloid leukemia (AML). Although most RUNX1 mutations in this disease are believed to be acquired, they can also be germline. Indeed, germline RUNX1 mutations result in the well-described autosomal-dominant familial platelet disorder with predisposition to hematologic malignancies (RUNX1-FPD, FPD/AML, FPDMM); ∼44% of affected individuals progress to AML or myelodysplastic syndromes. Using the Leucegene RUNX1 AML patient group, we sought to investigate the proportion of germline vs acquired RUNX1 mutations in this cohort. Our results showed that 30% of RUNX1 mutations in our AML cohort are germline. Molecular profiling revealed higher frequencies of NRAS mutations and other mutations known to activate various signaling pathways in these patients with RUNX1 germline-mutated AML. Moreover, 2 patients (mother and son) had co-occurrence of RUNX1 and CEBPA germline mutations, with variable AML disease onset at 59 and 27 years, respectively. Together, these data suggest a higher than anticipated frequency of germline RUNX1 mutations in the Leucegene cohort and further highlight the importance of testing for RUNX1 mutations in instances in which allogeneic stem cell transplantation using a related donor is envisioned., (© 2020 by The American Society of Hematology.)