bims-tremyl 2024-05-05 papers

on Therapy resistance biology in myeloid leukemia

Issue of 2024–05–05
twenty-six papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London

Molecular, clinical and therapeutic determinants of outcome in NPM1 mutated AML.
Molecular and clinical presentation of UBA1-mutated myelodysplastic syndromes.
Outcomes and genetic dynamics of acute myeloid leukemia at first relapse.
Clonal hematopoiesis-derived therapy-related myeloid neoplasms after autologous hematopoietic stem cell transplant for lymphoid and non-lymphoid disorders.
BRAF mutation in myeloid neoplasm: incidences and clinical outcomes.
Modeling and therapeutic targeting of t(8;21) AML with/without TP53 deficiency.
Measurable Residual FLT3 Internal Tandem Duplication Before Allogeneic Transplant for Acute Myeloid Leukemia.
Combined Effects of Clonal Hematopoiesis and Carotid Stenosis on Cardiovascular Mortality.
Kinase-inactivated CDK6 preserves the long-term functionality of adult hematopoietic stem cells.
GPATCH8 modulates mutant SF3B1 mis-splicing and pathogenicity in hematologic malignancies.
Ubiquitin-specific protease 7 inhibitors reveal a differentiated mechanism of p53-driven anti-cancer activity.
Efficacy of Venetoclax and Azacitidine in Acute Myeloid Leukemia Compared to Azacitidine Monotherapy: Real-World Experience.
A systematic review of second-generation FLT3 inhibitors for treatment of patients with relapsed/refractory acute myeloid leukemia.
Ribosome subunit attrition and activation of the p53-MDM4 axis dominate the response of MLL-rearranged cancer cells to WDR5 WIN site inhibition.
Enhanced Molecular Response in Myeloproliferative Neoplasms with Complete JAK2V617F Inhibition.
Continuously improving outcome over time after second allogeneic stem cell transplantation in relapsed acute myeloid leukemia: an EBMT registry analysis of 1540 patients.
Emetine induces oxidative stress, cell differentiation and NF-κB inhibition, suppressing AML stem/progenitor cells.
Racial and ethnic disparities in Acute Myeloid Leukemia: 15-year experience at a safety net hospital system.
HA-1-targeted T cell receptor (TCR) T cell therapy for recurrent leukemia after hematopoietic stem cell transplantation.
The epigenetic regulators EP300/CREBBP represent promising therapeutic targets in MLL-rearranged acute myeloid leukemia.
Expectations and outcomes of varying treatment strategies for CML presenting during pregnancy.
The initial molecular response predicts the deep molecular response but not treatment-free remission maintenance in a real-world chronic myeloid leukemia cohort.
Diagnosis of systemic mastocytosis with cryptic deletion of TET2 and DNMT3A resulting from unbalanced translocation.
Autoimmune myelofibrosis: A Mayo Clinic series of 22 patients.
Structural basis of lipid head group entry to the Kennedy pathway by FLVCR1.
High CD34-positive cell dose in matched unrelated donor allogeneic hematopoietic stem cell transplant is not associated with graft-versus-host disease or mortality.

Blood. 2024 May 01. pii: blood.2024024310. [Epub ahead of print]

Molecular, clinical and therapeutic determinants of outcome in NPM1 mutated AML.

Jad Othman, Nicola Potter, Adam Ivey, Yanis Tazi, Elli Papaemmanuil, Jelena Jovanovic, Sylvie D Freeman, Amanda Frances Gilkes, Rosemary E Gale, Tanya Rapoz-D'Silva, Manohursingh Runglall, Michelle Kleeman, Pawan Dhami, Ian Thomas, Sean Johnson, Joanna Canham, James Durrell Cavenagh, Panagiotis Kottaridis, Claire Arnold, Hans Beier Ommen, Ulrik Malthe Overgaard, Mike Dennis, Alan Kenneth Burnett, Charlotte S Wilhelm-Benartzi, Brian Jp Huntly, Nigel H Russell, Richard James Dillon.

Although NPM1-mutated acute myeloid leukemia (AML) carries a generally favorable prognosis, many patients still relapse and die. Previous studies identified several molecular and clinical features associated with poor outcome, however only FLT3-ITD mutation and adverse karyotype are currently used for risk stratification due to inconsistent results and uncertainty around how other factors should influence treatment, particularly given the strong prognostic impact of post-induction measurable residual disease (MRD). Here we analyzed a large group of patients with NPM1mut AML enrolled in prospective trials (NCRI AML17 and AML19, n=1357) to delineate the impact of baseline molecular and clinical features, post induction MRD status and treatment intensity on outcome. FLT3-ITD (HR 1.28, 95%CI 1.01-1.63), DNMT3A (HR 1.65, 95%CI 1.32-2.05), WT1 (HR 1.74, 95%CI 1272-2.38) and non-ABD NPM1 mutations (HR 1.64, 95%CI 1.22-2.21) were independently associated with poorer overall survival (OS). These factors were also strongly associated with MRD positivity. For patients achieving MRD negativity, these mutations (except FLT3-ITD) were associated with an increased cumulative incidence of relapse (CIR) and poorer OS. However, apart from the few patients with adverse cytogenetics, we could not identify any group of MRD negative patients with a CIR >40% or with benefit from allograft in first remission. Intensified chemotherapy with the FLAG-Ida regimen was associated with improved outcomes in all subgroups, with greater benefits observed in the highest risk molecular subgroups.

DOI: https://doi.org/10.1182/blood.2024024310
Blood. 2024 04 30. pii: blood.2023023723. [Epub ahead of print]

Molecular and clinical presentation of UBA1-mutated myelodysplastic syndromes.

Maria Sirenko, Elsa Bernard, Maria Creignou, Dylan Domenico, Andrea Farina, Juan Esteban Arango Ossa, Olivier Kosmider, Robert P Hasserjian, Martin Jädersten, Ulrich Germing, Guillermo F Sanz, Arjan A van de Loosdrecht, Carmelo Gurnari, Matilde Y Follo, Felicitas R Thol, Lurdes Zamora, Ronald Feitosa Pinheiro, Andrea Pellagatti, Harold Kunal Elias, Detlef Thomas Haase, Birgitta Sander, Elisa Orna, Katharina Zoldan, Lea Naomi Eder, Wolfgang R Sperr, Renate Thalhammer, Christina Ganster, Lionel Adès, Magnus Tobiasson, Laura Palomo, Matteo Giovanni Della Porta, Kety H Huberman, Pierre Fenaux, Monika Belickova, Michael R Savona, Virginia Klimek, Fabio P S Santos, Jacqueline Boultwood, Ioannis Kotsianidis, Valeria Santini, Francesc Sole, Uwe Platzbecker, Michael Heuser, Peter Valent, Carlo Finelli, Maria Teresa Voso, Lee Yung Shih, Seishi Ogawa, Michaela Fontenay, Joop H Jansen, José Cervera, Benjamin L Ebert, Rafael Bejar, Peter L Greenberg, Norbert Gattermann, Luca Malcovati, Mario Cazzola, David B Beck, Eva S Hellstrom-Lindberg, Elli Papaemmanuil.

Mutations in UBA1, which are disease-defining for VEXAS syndrome, have been reported in patients diagnosed with myelodysplastic syndromes (MDS). Here, we define the prevalence and clinical associations of UBA1 mutations in a representative cohort of patients with MDS. Digital droplet PCR profiling of a selected cohort of 375 male patients lacking MDS disease-defining mutations or established WHO disease classification identified 28 patients (7%) with UBA1 p.M41T/V/L mutations. Using targeted sequencing of UBA1 in a representative MDS cohort (n=2,027), we identified an additional 27 variants in 26 patients (1%), which we classified as likely/pathogenic (n=12) and unknown significance (n=15). Among the total 40 patients with likely/pathogenic variants (2%), all were male and 63% were classified by WHO2016 as MDS-MLD/SLD. Patients had a median of one additional myeloid gene mutation, often in TET2 (n=12), DNMT3A (n=10), ASXL1 (n=3), or SF3B1 (n=3). Retrospective clinical review where possible showed that 83% (28/34) UBA1-mutant cases had VEXAS-associated diagnoses or inflammatory clinical presentation. The prevalence of UBA1-mutations in MDS patients argues for systematic screening for UBA1 in the management of MDS.

DOI: https://doi.org/10.1182/blood.2023023723
Haematologica. 2024 May 02.

Outcomes and genetic dynamics of acute myeloid leukemia at first relapse.

Alex Bataller, Hagop Kantarjian, Alexandre Bazinet, Tapan Kadia, Naval Daver, Courtney D DiNardo, Gautam Borthakur, Sanam Loghavi, Keyur Patel, Guilin Tang, Koji Sasaki, Nicholas J Short, Musa Yilmaz, Ghayas C Issa, Yesid Alvarado, Guillermo Montalban-Bravo, Abhishek Maiti, Hussein A Abbas, Koichi Takahashi, Sherry Pierce, Elias Jabbour, Guillermo Garcia-Manero, Farhad Ravandi.

Patients with relapsed acute myeloid leukemia (rAML) experience dismal outcomes. We performed a comprehensive analysis of patients with rAML to determine the genetic dynamics and survival predictive factors. We analyzed 875 patients with newly diagnosed AML who received intensive treatment (IT) or low-intensity treatment (LIT). Of these patients, 197 experienced subsequent rAML. Data was available for 164 patients, with a median time from CR/CRi to relapse of 6.5 months. Thirty-five of the 164 patients (21%) experienced relapse after allogeneic hematopoietic stem cell transplantation (alloSCT). At relapse mutations in genes involved in pathway signaling tended to disappear, whereas clonal hematopoiesis-related mutations or TP53 tended to persist. Patients with normal karyotypes tended to acquire cytogenetic abnormalities at relapse. Patients treated with IT had a higher emergence rate of TP53 mutations (16%), compared to patients treated with LIT (1%, P = 0.009). The overall response rates were 38% and 35% for patients treated with salvage IT or LIT, respectively. Seventeen patients (10%) underwent alloSCT after salvage therapy. The median overall survival (OS) duration after relapse was 5.3 months, with a 1-year OS rate of 17.6%. Complex karyotype (hazard ratio [HR] = 2.14, P < 0.001), a KMT2A rearrangement (HR = 3.52, P = 0.011), time in remission < 12 months (HR = 1.71, P = 0.011), and an elevated white blood cell count at relapse (HR = 2.38, P = 0.005) were independent risk factors for OS duration. More effective frontline and maintenance therapies are warranted to prevent rAML.

DOI: https://doi.org/10.3324/haematol.2024.285057
Leukemia. 2024 Apr 29.

Clonal hematopoiesis-derived therapy-related myeloid neoplasms after autologous hematopoietic stem cell transplant for lymphoid and non-lymphoid disorders.

Hussein Awada, Carmelo Gurnari, Valeria Visconte, Arda Durmaz, Teodora Kuzmanovic, Hassan Awada, Zheng Jin Tu, James R Cook, Brian J Bolwell, Ronald Sobecks, Matt Kalaycio, David Bosler, Jaroslaw P Maciejewski.

Therapy-related myeloid neoplasms (tMN) are complications of cytotoxic therapies. Risk of tMN is high in recipients of autologous hematopoietic stem cell transplantation (aHSCT). Acquisition of genomic mutations represents a key pathogenic driver but the origins, timing and dynamics, particularly in the context of preexisting or emergent clonal hematopoiesis (CH), have not been sufficiently clarified. We studied a cohort of 1507 patients undergoing aHSCT and a cohort of 263 patients who developed tMN without aHSCT to determine clinico-molecular features unique to post-aHSCT tMN. We show that tMN occurs in up to 2.3% of patients at median of 2.6 years post-AHSCT. Age ≥ 60 years, male sex, radiotherapy, high treatment burden ( ≥ 3 lines of chemotherapy), and graft cellularity increased the risk of tMN. Time to evolution and overall survival were shorter in post-aHSCT tMN vs. other tMN, and the earlier group's mutational pattern was enriched in PPM1D and TP53 lesions. Preexisting CH increased the risk of adverse outcomes including post-aHSCT tMN. Particularly, antecedent lesions affecting PPM1D and TP53 predicted tMN evolution post-transplant. Notably, CH-derived tMN had worse outcomes than non CH-derived tMN. As such, screening for CH before aHSCT may inform individual patients' prognostic outcomes and influence their prospective treatment plans. Presented in part as an oral abstract at the 2022 American Society of Hematology Annual Meeting, New Orleans, LA, 2022.

DOI: https://doi.org/10.1038/s41375-024-02258-y
Leuk Lymphoma. 2024 May 02. 1-6

BRAF mutation in myeloid neoplasm: incidences and clinical outcomes.

Tareq Abuasab, Shehab Mohamed, Naveen Pemmaraju, Tapan M Kadia, Naval Daver, Courtney D DiNardo, Farhad Ravandi, Wei Qiao, Guillermo Montalban-Bravo, Gautam Borthakur.

  The presence of BRAF mutation in hematological malignancies, excluding Hairy cell leukemia, and its significance as a driver mutation in myeloid neoplasms (MNs) remains largely understudied. This research aims to evaluate patient characteristics and outcomes of BRAF-mutated MNs. Among a cohort of 6667 patients, 48 (0.7%) had BRAF-mutated MNs. Notably, three patients exhibited sole BRAF mutation, providing evidence supporting the hypothesis of BRAF's role as a driver mutation in MNs. In acute myeloid leukemia, the majority of patients had secondary acute myeloid leukemia, accompanied by poor-risk cytogenic and RAS pathway mutations. Although the acquisition of BRAF mutation during disease progression did not correlate with unfavorable outcomes, its clearance through chemotherapy or stem cell transplant exhibited favorable outcomes (median overall survival of 34.8 months versus 10.4 months, p = 0.047). Furthermore, G469A was the most frequently observed BRAF mutation, differing from solid tumors and hairy cell leukemia, where V600E mutations were predominant.

Keywords:  BRAF mutation; acute myeloid leukemia; chronic myelomonocytic leukemia; myelodysplastic syndrome; myeloproliferative neoplasm

DOI:  https://doi.org/10.1080/10428194.2024.2347539
Int J Hematol. 2024 May 03.

Modeling and therapeutic targeting of t(8;21) AML with/without TP53 deficiency.

Wenyu Zhang, Jingmei Li, Keita Yamamoto, Susumu Goyama.

  Acute myeloid leukemia (AML) with t(8;21)(q22;q22.1);RUNX1-ETO is one of the most common subtypes of AML. Although t(8;21) AML has been classified as favorable-risk, only about half of patients are cured with current therapies. Several genetic abnormalities, including TP53 mutations and deletions, negatively impact survival in t(8;21) AML. In this study, we established Cas9+ mouse models of t(8;21) AML with intact or deficient Tpr53 (a mouse homolog of TP53) using a retrovirus-mediated gene transfer and transplantation system. Trp53 deficiency accelerates the in vivo development of AML driven by RUNX1-ETO9a, a short isoform of RUNX1-ETO with strong leukemogenic potential. Trp53 deficiency also confers resistance to genetic depletion of RUNX1 and a TP53-activating drug in t(8;21) AML. However, Trp53-deficient t(8;21) AML cells were still sensitive to several drugs such as dexamethasone. Cas9+ RUNX1-ETO9a cells with/without Trp53 deficiency can produce AML in vivo, can be cultured in vitro for several weeks, and allow efficient gene depletion using the CRISPR/Cas9 system, providing useful tools to advance our understanding of t(8;21) AML.

Keywords:  AML; CRISPR/Cas9; Mouse model; RUNX1-ETO; TP53

DOI:  https://doi.org/10.1007/s12185-024-03783-3
JAMA Oncol. 2024 May 02.

Measurable Residual FLT3 Internal Tandem Duplication Before Allogeneic Transplant for Acute Myeloid Leukemia.

Laura W Dillon, Gege Gui, Niveditha Ravindra, Georgia Andrew, Devdeep Mukherjee, Zoë C Wong, Ying Huang, Jason Gerhold, Matt Holman, Julian D'Angelo, Jeffrey Miller, Jake Higgins, Jesse J Salk, Jeffery J Auletta, Firas El Chaer, Steven M Devine, Antonio Martin Jimenez-Jimenez, Marcos J G De Lima, Mark R Litzow, Partow Kebriaei, Wael Saber, Stephen R Spellman, Scott L Zeger, Kristin M Page, Christopher S Hourigan.

Importance: Persistence of FLT3 internal tandem duplication (ITD) in adults with acute myeloid leukemia (AML) in first complete remission (CR) prior to allogeneic hematopoietic cell transplant (HCT) is associated with increased relapse and death after transplant, but the association between the level of measurable residual disease (MRD) detected and clinical outcome is unknown.
Objective: To examine the association between pre-allogeneic HCT MRD level with relapse and death posttransplant in adults with AML in first CR.
Design, Setting, and Participants: In this cohort study, DNA sequencing was performed on first CR blood from patients with FLT3-ITD AML transplanted from March 2013 to February 2019. Clinical follow-up was through May 2022. Data were analyzed from October 2022 to December 2023.
Exposure: Centralized DNA sequencing for FLT3-ITD in pre-allogeneic HCT first CR blood using a commercially available kit.
Main Outcomes and Measures: The primary outcomes were overall survival and cumulative incidence of relapse, with non-relapse-associated mortality as a competing risk post-allogeneic HCT. Kaplan-Meier estimations (log-rank tests), Cox proportional hazards models, and Fine-Gray models were used to estimate the end points.
Results: Of 537 included patients with FLT3-ITD AML from the Pre-MEASURE study, 296 (55.1%) were female, and the median (IQR) age was 55.6 (42.9-64.1) years. Using the variant allele fraction (VAF) threshold of 0.01% or greater for MRD positivity, the results closely aligned with those previously reported. With no VAF threshold applied (VAF greater than 0%), 263 FLT3-ITD variants (median [range] VAF, 0.005% [0.0002%-44%]), and 177 patients (33.0%) with positive findings were identified. Multivariable analyses showed that residual FLT3-ITD was the variable most associated with relapse and overall survival, with a dose-dependent correlation. Patients receiving reduced-intensity conditioning without melphalan or nonmyeloablative conditioning had increased risk of relapse and death at any given level of MRD compared with those receiving reduced-intensity conditioning with melphalan or myeloablative conditioning.
Conclusions and Relevance: This study provides generalizable and clinically applicable evidence that the detection of residual FLT3-ITD in the blood of adults in first CR from AML prior to allogeneic HCT is associated with an increased risk of relapse and death, particularly for those with a VAF of 0.01% or greater. While transplant conditioning intensification, an intervention not available to all, may help mitigate some of this risk, alternative approaches will be necessary for this high-risk population of patients who are underserved by the current standard of care.

DOI: https://doi.org/10.1001/jamaoncol.2024.0985
J Am Coll Cardiol. 2024 May 07. pii: S0735-1097(24)00941-0. [Epub ahead of print]83(18): 1717-1727

Combined Effects of Clonal Hematopoiesis and Carotid Stenosis on Cardiovascular Mortality.

Roland Jäger, Matthias Hoke, Florian J Mayer, Stefanie Boden, Cornelia Englisch, Cihan Ay, Robert Kralovics, Christoph J Binder.

   BACKGROUND: The expansion of hematopoietic stem cells caused by acquired somatic mutations (clonal hematopoiesis [CH]) is a novel cardiovascular risk factor. The prognostic value of CH in patients with carotid atherosclerosis remains to be evaluated.
OBJECTIVES: This study assessed the prognostic significance of CH in patients with atherosclerosis as detected by ultrasound of the carotid artery.
METHODS: We applied deep sequencing of selected genomic regions within the genes DNMT3A, TET2, ASXL1, and JAK2 to screen for CH in 968 prospectively collected patients with asymptomatic carotid atherosclerosis evaluated by duplex sonography.
RESULTS: We detected clonal markers at variant allele frequency ≥2% in 133 (13.7%) of 968 patients (median age 69.2 years), with increasing prevalence at advanced age. Multivariate analyses including age and established cardiovascular risk factors revealed overall presence of CH to be significantly associated with increased risk of cardiovascular death (HR: 1.50; 95% CI: 1.12-2.00; P = 0.007), reflected also at the single gene level. The effect of CH was more pronounced in older patients and independent of the patients' inflammatory status as measured by high-sensitivity C-reactive protein. Simultaneous assessment of CH and degree of carotid stenosis revealed combined effects on cardiovascular mortality, depicted by a superior risk for patients with >50% stenosis and concomitant CH (adjusted HR: 1.60; 95% CI: 1.08-2.38; P = 0.020).
CONCLUSIONS: CH status in combination with the extent of carotid atherosclerosis jointly predict long-term mortality. Determination of CH can provide additional prognostic information in patients with asymptomatic carotid atherosclerosis.

Keywords:  aging; carotid atherosclerosis; clonality; inflammation; prognosis; risk prediction

DOI:  https://doi.org/10.1016/j.jacc.2024.02.043
Blood. 2024 Apr 29. pii: blood.2023021985. [Epub ahead of print]

Kinase-inactivated CDK6 preserves the long-term functionality of adult hematopoietic stem cells.

Isabella Maria Mayer, Eszter Doma, Thorsten Klampfl, Michaela Prchal-Murphy, Sebastian Kollmann, Alessia Schirripa, Lisa Scheiblecker, Markus Zojer, Natalia Kunowska, Lea Gebrail, Lisa E Shaw, Ulrike Mann, Alex Farr, Reinhard Grausenburger, Gerwin Heller, Eva Zebedin-Brandl, Matthias Farlik, Marcos Malumbres, Veronika Sexl, Karoline Kollmann.

Hematopoietic stem cells (HSCs) are characterized by the ability to self-renew and to replenish the hematopoietic system. The cell-cycle kinase cyclin dependent-kinase 6 (CDK6) regulates transcription, whereby it has both kinase-dependent and kinase-independent functions. We here describe the complex role of CDK6, balancing quiescence, proliferation, self-renewal and differentiation in activated HSCs. Mouse HSCs expressing kinase-inactivated CDK6 show enhanced long-term repopulation and homing, whereas HSCs lacking CDK6 have impaired functionality. The transcriptomes of basal and serially transplanted HSCs expressing kinase-inactivated CDK6 exhibit an expression pattern dominated by HSC quiescence and self-renewal, proposing a concept where MAZ and NFY-A are critical CDK6 interactors. Pharmacologic kinase inhibition with a clinically used CDK4/6 inhibitor in murine and human HSCs validated our findings and resulted in increased repopulation capability and enhanced stemness. Our findings highlight a kinase-independent role of CDK6 in long-term HSC functionality. CDK6 kinase inhibition represents a possible strategy to improve HSC fitness.

DOI: https://doi.org/10.1182/blood.2023021985
Mol Cell. 2024 Apr 21. pii: S1097-2765(24)00284-3. [Epub ahead of print]

GPATCH8 modulates mutant SF3B1 mis-splicing and pathogenicity in hematologic malignancies.

Salima Benbarche, Jose Mario Bello Pineda, Laura Baquero Galvis, Jeetayu Biswas, Bo Liu, Eric Wang, Qian Zhang, Simon J Hogg, Kadeen Lyttle, Ariana Dahi, Alexander M Lewis, Martina Sarchi, Jahan Rahman, Nina Fox, Yuxi Ai, Sanjoy Mehta, Ralph Garippa, Juliana Ortiz-Pacheco, Zhuoning Li, Mara Monetti, Robert F Stanley, Sergei Doulatov, Robert K Bradley, Omar Abdel-Wahab.

  Mutations in the RNA splicing factor gene SF3B1 are common across hematologic and solid cancers and result in widespread alterations in splicing, yet there is currently no therapeutic means to correct this mis-splicing. Here, we utilize synthetic introns uniquely responsive to mutant SF3B1 to identify trans factors required for aberrant mutant SF3B1 splicing activity. This revealed the G-patch domain-containing protein GPATCH8 as required for mutant SF3B1-induced splicing alterations and impaired hematopoiesis. GPATCH8 is involved in quality control of branchpoint selection, interacts with the RNA helicase DHX15, and functionally opposes SURP and G-patch domain containing 1 (SUGP1), a G-patch protein recently implicated in SF3B1-mutant diseases. Silencing of GPATCH8 corrected one-third of mutant SF3B1-dependent splicing defects and was sufficient to improve dysfunctional hematopoiesis in SF3B1-mutant mice and primary human progenitors. These data identify GPATCH8 as a novel splicing factor required for mis-splicing by mutant SF3B1 and highlight the therapeutic impact of correcting aberrant splicing in SF3B1-mutant cancers.

Keywords:  DHX15; G-patch domain; GPATCH8; RNA; SF3B1; SUGP1; leukemia; myelodysplastic syndromes; splicing

DOI:  https://doi.org/10.1016/j.molcel.2024.04.006
iScience. 2024 May 17. 27(5): 109693

Ubiquitin-specific protease 7 inhibitors reveal a differentiated mechanism of p53-driven anti-cancer activity.

Alan S Futran, Tao Lu, Katherine Amberg-Johnson, Jiayi Xu, Xiaoxiao Yang, Saidi He, Sarah Boyce, Jeffrey A Bell, Robert Pelletier, Takao Suzuki, Xianhai Huang, Heng Qian, Liping Fang, Li Xing, Zhaowu Xu, Stephen E Kurtz, Jeffrey W Tyner, Wayne Tang, Tao Guo, Karen Akinsanya, David Madge, Kristian K Jensen.

  The USP7 deubiquitinase regulates proteins involved in the cell cycle, DNA repair, and epigenetics and has been implicated in cancer progression. USP7 inhibition has been pursued for the development of anti-cancer therapies. Here, we describe the discovery of potent and specific USP7 inhibitors exemplified by FX1-5303. FX1-5303 was used as a chemical probe to study the USP7-mediated regulation of p53 signaling in cells. It demonstrates mechanistic differences compared to MDM2 antagonists, a related class of anti-tumor agents that act along the same pathway. FX1-5303 synergizes with the clinically approved BCL2 inhibitor venetoclax in acute myeloid leukemia (AML) cell lines and ex vivo patient samples and leads to strong tumor growth inhibition in in vivo mouse xenograft models of multiple myeloma and AML. This work introduces new USP7 inhibitors, differentiates their mechanism of action from MDM2 inhibition, and identifies specific opportunities for their use in the treatment of AML.

Keywords:  Biochemistry; Cancer; Cell biology

DOI:  https://doi.org/10.1016/j.isci.2024.109693
Anticancer Res. 2024 May;44(5): 2003-2007

Efficacy of Venetoclax and Azacitidine in Acute Myeloid Leukemia Compared to Azacitidine Monotherapy: Real-World Experience.

Yuta Baba, Noriko Hida, Takehiko Sambe, Maasa Abe, Nobuyuki Kabasawa, Hirotaka Sakai, Kiyoshi Yoshimura, Tetsuya Fukuda.

   BACKGROUND/AIM: The combination of venetoclax (VEN) and azacitidine (AZA) (VEN+AZA) leads to higher complete remission rates and longer overall survival (OS) in patients with untreated acute myeloid leukemia (AML) who are ineligible for intensive combination chemotherapy. In practice, the doses of VEN and AZA are reduced at the attending physician's discretion to avoid adverse events; however, the impact of dose and duration reductions has not been fully clarified. We analyzed whether the efficacy was maintained with reduced VEN+AZA compared to AZA monotherapy in the real world.
PATIENTS AND METHODS: A total of 33 patients were included; 17 (10 newly diagnosed, 7 primary refractory or relapsed) received VEN+AZA, and 16 (7 newly diagnosed, 9 primary refractory or relapsed) received AZA. We analyzed complete remission (CR) and CR with incomplete hematologic recovery (CRi) rates, OS, and the incidence of adverse events.
RESULTS: CR/CRi were achieved in 7/17 (41.2%) and 11/17 (64.7%) patients in the VEN+AZA group and 0/15 (0%) and 2/15 (6.7%) patients in the AZA group, respectively. The CR/CRi rate was higher in the VEN+AZA group than in the AZA group (p=0.001). OS was longer in the VEN+AZA group than in the AZA group (p=0.03), with a median of 506 days [95% confidence interval (CI)=234-585 days] and 208 days (95% CI=52-343 days), respectively.
CONCLUSION: The doses of the VEN+AZA combination were reduced at the attending physician's discretion, resulting in a higher CR/CRi rate and longer OS than AZA monotherapy and is considered useful for AML in the real world.

Keywords:  Venetoclax; acute myeloid leukemia; azacitidine; real-world experience; reduction rate

DOI:  https://doi.org/10.21873/anticanres.17003
Leuk Res. 2024 Apr 17. pii: S0145-2126(24)00071-7. [Epub ahead of print]141 107505

A systematic review of second-generation FLT3 inhibitors for treatment of patients with relapsed/refractory acute myeloid leukemia.

Alireza Mohebbi, Fahimeh Shahriyary, Vida Farrokhi, Bita Bandar, Najmaldin Saki.

   BACKGROUND: Acute myeloid leukemia (AML) is a complex disease with diverse mutations, including prevalent mutations in the FMS-like receptor tyrosine kinase 3 (FLT3) gene that lead to poor prognosis. Recent advancements have introduced FLT3 inhibitors that have improved outcomes for FLT3-mutated AML patients, however, questions remain on their application in complex conditions such as relapsed/refractory (R/R) disease. Therefore, we aimed to evaluate the clinical effectiveness of second-generation FLT3 inhibitors in treating patients with R/R AML.
METHODS: A systematic literature search of PubMed, MEDLINE, SCOPUS and Google Scholar databases was made to identify relevant studies up to January 30, 2024. This study was conducted following the guidelines of the PRISMA.
RESULTS: The ADMIRAL trial revealed significantly improved overall survival and complete remission rates with gilteritinib compared to salvage chemotherapy, with manageable adverse effects. Ongoing research explores its potential in combination therapies, showing synergistic effects with venetoclax and promising outcomes in various clinical trials. The QuANTUM-R trial suggested longer overall survival with quizartinib compared to standard chemotherapy, although concerns were raised regarding trial design and cardiotoxicity. Ongoing research explores combination therapies involving quizartinib, such as doublet or triplet regimens with venetoclax, showing promising outcomes in FLT3-mutated AML patients.
CONCLUSION: These targeted therapies offer promise for managing this subgroup of AML patients, but further research is needed to optimize their use. This study underscores the importance of personalized treatment based on genetic mutations in AML, paving the way for more effective and tailored approaches to combat the disease.

Keywords:  AML; FLT3; FLT3 Inhibitor; Relapse/Refractory

DOI:  https://doi.org/10.1016/j.leukres.2024.107505
Elife. 2024 Apr 29. pii: RP90683. [Epub ahead of print]12

Ribosome subunit attrition and activation of the p53-MDM4 axis dominate the response of MLL-rearranged cancer cells to WDR5 WIN site inhibition.

Gregory Caleb Howard, Jing Wang, Kristie L Rose, Camden Jones, Purvi Patel, Tina Tsui, Andrea C Florian, Logan Vlach, Shelly L Lorey, Brian C Grieb, Brianna N Smith, Macey J Slota, Elizabeth M Reynolds, Soumita Goswami, Michael R Savona, Frank M Mason, Taekyu Lee, Stephen Fesik, Qi Liu, William P Tansey.

  The chromatin-associated protein WD Repeat Domain 5 (WDR5) is a promising target for cancer drug discovery, with most efforts blocking an arginine-binding cavity on the protein called the 'WIN' site that tethers WDR5 to chromatin. WIN site inhibitors (WINi) are active against multiple cancer cell types in vitro, the most notable of which are those derived from MLL-rearranged (MLLr) leukemias. Peptidomimetic WINi were originally proposed to inhibit MLLr cells via dysregulation of genes connected to hematopoietic stem cell expansion. Our discovery and interrogation of small-molecule WINi, however, revealed that they act in MLLr cell lines to suppress ribosome protein gene (RPG) transcription, induce nucleolar stress, and activate p53. Because there is no precedent for an anticancer strategy that specifically targets RPG expression, we took an integrated multi-omics approach to further interrogate the mechanism of action of WINi in human MLLr cancer cells. We show that WINi induce depletion of the stock of ribosomes, accompanied by a broad yet modest translational choke and changes in alternative mRNA splicing that inactivate the p53 antagonist MDM4. We also show that WINi are synergistic with agents including venetoclax and BET-bromodomain inhibitors. Together, these studies reinforce the concept that WINi are a novel type of ribosome-directed anticancer therapy and provide a resource to support their clinical implementation in MLLr leukemias and other malignancies.

Keywords:  WDR5; cancer biology; cancer therapy; chromosomes; gene expression; human; p53; ribosomes

DOI:  https://doi.org/10.7554/eLife.90683
Cancer Discov. 2024 May 01. 14(5): 701-703

Enhanced Molecular Response in Myeloproliferative Neoplasms with Complete JAK2V617F Inhibition.

Hamza Celik, Grant A Challen.

SUMMARY: Dunbar, Bowman, and colleagues present here a novel genetic mouse model with inducible and reversible expression of the JAK2V617F mutation in the endogenous locus. Results from this study clearly demonstrate an absolute requirement for myeloproliferative neoplasm-initiating cells for this mutation in their survival and imply that more efficacious inhibitors could be curative for these patients even in the setting of additional cooperating mutations. See related article by Dunbar et al., p. 737 (8).

DOI: https://doi.org/10.1158/2159-8290.CD-23-1522
Blood Cancer J. 2024 May 02. 14(1): 76

Continuously improving outcome over time after second allogeneic stem cell transplantation in relapsed acute myeloid leukemia: an EBMT registry analysis of 1540 patients.

Ann-Kristin Schmälter, Maud Ngoya, Jacques-Emmanuel Galimard, Ali Bazarbachi, Jürgen Finke, Nicolaus Kröger, Martin Bornhäuser, Matthias Stelljes, Friedrich Stölzel, Johanna Tischer, Thomas Schroeder, Peter Dreger, Igor-Wolfgang Blau, Bipin Savani, Sebastian Giebel, Jordi Esteve, Arnon Nagler, Christoph Schmid, Fabio Ciceri, Mohamad Mohty.

Second allogeneic stem cell transplantation (alloSCT2) is among the most effective treatments for acute myeloid leukemia (AML) relapse after first alloSCT (alloSCT1). Long-term EBMT registry data were used to provide large scale, up-to-date outcome results and to identify factors for improved outcome. Among 1540 recipients of alloSCT2, increasing age, better disease control and performance status before alloSCT2, more use of alternative donors and higher conditioning intensity represented important trends over time. Between the first (2000-2004) and last (2015-2019) period, two-year overall and leukemia-free survival (OS/LFS) increased considerably (OS: 22.5-35%, LFS: 14.5-24.5%). Cumulative relapse incidence (RI) decreased from 64% to 50.7%, whereas graft-versus-host disease and non-relapse mortality (NRM) remained unchanged. In multivariable analysis, later period of alloSCT2 was associated with improved OS/LFS (HR = 0.47/0.53) and reduced RI (HR = 0.44). Beyond, remission duration, disease stage and patient performance score were factors for OS, LFS, RI, and NRM. Myeloablative conditioning for alloSCT2 decreased RI without increasing NRM, leading to improved OS/LFS. Haploidentical or unrelated donors and older age were associated with higher NRM and inferior OS. In summary, outcome after alloSCT2 has continuously improved over the last two decades despite increasing patient age. The identified factors provide clues for the optimized implementation of alloSCT2.

DOI: https://doi.org/10.1038/s41408-024-01060-4
Cell Death Discov. 2024 Apr 29. 10(1): 201

Emetine induces oxidative stress, cell differentiation and NF-κB inhibition, suppressing AML stem/progenitor cells.

Suellen L R Silva, Ingrid R S B Dias, Ana Carolina B da C Rodrigues, Rafaela G A Costa, Maiara de S Oliveira, Gabriela A da C Barbosa, Milena B P Soares, Rosane B Dias, Ludmila F Valverde, Clarissa A G Rocha, Nainita Roy, Christopher Y Park, Daniel P Bezerra.

Acute myeloid leukemia (AML) is a fatal malignancy of the blood and bone marrow. Leukemic stem cells (LSCs) are a rare subset of leukemic cells that promote the development and progression of AML, and eradication of LSCs is critical for effective control of this disease. Emetine is an FDA-approved antiparasitic drug with antitumor properties; however, little is known about its potential against LSCs. Herein, we explored the antileukemic potential of emetine, focusing on its effects on AML stem/progenitor cells. Emetine exhibited potent cytotoxic activity both in hematologic and solid cancer cells and induced AML cell differentiation. Emetine also inhibited AML stem/progenitor cells, as evidenced by decreased expression of CD34, CD97, CD99, and CD123 in KG-1a cells, indicating anti-AML stem/progenitor cell activities. The administration of emetine at a dosage of 10 mg/kg for two weeks showed no significant toxicity and significantly reduced xenograft leukemic growth in vivo. NF-κB activation was reduced in emetine-treated KG-1a cells, as shown by reduced phospho-NF-κB p65 (S529) and nuclear NF-κB p65. DNA fragmentation, YO-PRO-1 staining, mitochondrial depolarization and increased levels of active caspase-3 and cleaved PARP (Asp214) were detected in emetine-treated KG-1a cells. Moreover, treatment with the pancaspase inhibitor Z-VAD(OMe)-FMK partially prevented the apoptotic cell death induced by emetine. Emetine treatment also increased cellular and mitochondrial reactive oxygen species, and emetine-induced apoptosis in KG-1a cells was partially prevented by the antioxidant N-acetylcysteine, indicating that emetine induces apoptosis, at least in part, by inducing oxidative stress. Overall, these studies indicate that emetine is a novel potential anti-AML agent with promising activity against stem/progenitor cells, encouraging the development of further studies aimed at its clinical application.

DOI: https://doi.org/10.1038/s41420-024-01967-8
Leuk Res. 2024 Apr 15. pii: S0145-2126(24)00069-9. [Epub ahead of print]141 107503

Racial and ethnic disparities in Acute Myeloid Leukemia: 15-year experience at a safety net hospital system.

Sharlene Dong, Naveen Premnath, Navid Sadeghi, Radhika Kainthla, Stephen S Chung, Robert H Collins, Hsiao C Li, Yazan F Madanat.

  Despite recent therapeutic advances, ethnic minorities in the U.S. continue to have disproportionately poor outcomes in many hematologic malignancies including AML. We identified 162 adult AML patients treated at a non-transplant safety net hospital from 2007 to 2022 and evaluated differences in disease characteristics, treatment and clinical outcomes based on race and ethnicity. Our cohort consisted of 82 (50.6%) Hispanic, 36 (22.2%) non-Hispanic black and 44 (27.2%) non-Hispanic white and Asian patients. Median age at diagnosis was 42.5, 49.0 and 52.5 years respectively (p=0.025). Hispanics had higher rates of intermediate and high-risk disease (p=0.699) and received high intensity induction and consolidation chemotherapy at lower rates (p=0.962), although differences did not reach statistical significance. Despite this, similar remission rates were achieved. Hispanics with high-risk disease had longer overall survival (OS) than the combined non-Hispanic cohort (mOS 14 m vs 7 m, p=0.030). Multivariate regression analysis showed that OS was negatively associated with age (HR 1.023, p=0.006), intermediate (HR 3.431, p=0.0003) and high-risk disease (HR 4.689, p<0.0001) and positively associated with Hispanic ethnicity (HR 0.614, p=0.026). This report suggests that contrary to other studies, Hispanics, particularly those with high-risk AML, may have improved OS compared to other ethnic groups. These results are unique to our safety net hospital setting where common barriers to medical care and healthcare disparities are largely mitigated.

Keywords:  Acute Myeloid Leukemia; Healthcare disparities; Hematopoietic stem cell transplant; Outcomes; Safety net hospital; Survival

DOI:  https://doi.org/10.1016/j.leukres.2024.107503
Blood. 2024 Apr 29. pii: blood.2024024105. [Epub ahead of print]

HA-1-targeted T cell receptor (TCR) T cell therapy for recurrent leukemia after hematopoietic stem cell transplantation.

Elizabeth F Krakow, Michelle Brault, Corinne Summers, Tanya M Cunningham, Melinda A Biernacki, R Graeme Black, Kyle Blake Woodward, Nicole Vartanian, Sami B Kanaan, Albert C Yeh, Robson G Dossa, Merav Bar, Ryan D Cassaday, Ann Dahlberg, Brian G Till, Andrew E Denker, Cecilia C S Yeung, Ted A Gooley, David G Maloney, Stanley R Riddell, Philip D Greenberg, Aude G Chapuis, Evan W Newell, Scott N Furlan, Marie Bleakley.

Relapse is the leading cause of death after allogeneic hematopoietic stem cell transplantation (HCT) for leukemia. T cells engineered by gene transfer to express T cell receptors (TCR; TCR-T) specific for hematopoietic-restricted minor histocompatibility (H) antigens may provide a potent selective anti-leukemic effect post-HCT. We conducted a phase I clinical trial employing a novel TCR-T product targeting the minor H antigen HA-1 to treat or consolidate treatment of persistent or recurrent leukemia and myeloid neoplasms. The primary objective was to evaluate the feasibility and safety of administration of HA-1 TCR-T post-HCT. CD8+ and CD4+ T cells expressing the HA-1 TCR and a CD8-co-receptor were successfully manufactured from HA-1 disparate HCT donors. One or more infusions of HA-1 TCR-T following lymphodepleting chemotherapy were administered to nine HCT recipients who had developed disease recurrence post-HCT. TCR-T cells expanded and persisted in vivo after adoptive transfer. No dose-limiting toxicities occurred. Although the study was not designed to assess efficacy, four patients achieved or maintained complete remissions following lymphodepletion and HA-1 TCR-T, with one ongoing at >2 years. Single-cell RNA sequencing of relapsing/progressive leukemia after TCR-T therapy identified upregulated molecules associated with T cell dysfunction or cancer cell survival. HA-1 TCR-T therapy appears feasible and safe and shows preliminary signals of efficacy. This clinical trial is registered at clinicaltrials.gov as NCT03326921.

DOI: https://doi.org/10.1182/blood.2024024105
Cell Death Discov. 2024 May 01. 10(1): 206

The epigenetic regulators EP300/CREBBP represent promising therapeutic targets in MLL-rearranged acute myeloid leukemia.

Wenqi Wu, Yanan Jiang, Donghui Xing, Yixin Zhai, Huimeng Sun, Xiang He, Kaiping Luo, Pengpeng Xu, Feng Pan, Guolei Dong, Guibing Ren, Zhigang Zhao.

Acute myeloid leukemia (AML) with mixed-lineage leukemia (MLL) gene rearrangements (MLL-r) is an aggressive subtype of blood cancer with dismal prognosis, underscoring the urgent need for novel therapeutic strategies. E1A-binding protein (EP300) and CREB-binding protein (CREBBP) function as essential transcriptional coactivators and acetyltransferases, governing leukemogenesis through diverse mechanisms. Targeting EP300/CREBBP holds great promise for treating leukemia with some certain cytogenetic abnormalities. Here, we demonstrated that EP300 and CREBBP are core epigenetic regulators in the pathogenesis of MLL-r AML through assaying the transposase-accessible chromatin with high-throughput sequencing (ATAC-seq). Knocking-out EP300/CREBBP and inhibitor (A-485) treatment depressed the MLL-r cells proliferation, while the MLL wild-type cells remained uninfluenced. We found that the CDK4/RB/E2F axis was downregulated specifically in MLL-r AML cell after A-485 treatment by RNA-seq, western blot and cut-tag analyses. EP300/CREBBP inhibitor selectively exerted potent anti-leukemia activity through blocking the MLL-r-BET complex binding to H3K27Ac modification on critical genes loci, distinct from global histone acetylation. Collectively, our study identified EP300/CREBBP as a critical epigenetic driver of MLL-r leukemia and validated their therapeutic potential through targeting inhibition, offering a promising avenue for improving clinical outcomes in this aggressive leukemia.

DOI: https://doi.org/10.1038/s41420-024-01940-5
Br J Haematol. 2024 May 02.

Expectations and outcomes of varying treatment strategies for CML presenting during pregnancy.

H F Robertson, D Milojkovic, N Butt, J Byrne, S Claudiani, M Copland, P Gallipoli, A J Innes, K Knight, A J Mahdi, J Parker, A Virchis, J F Apperley.

  Diagnosing chronic myeloid leukaemia (CML) during pregnancy is rare. Tyrosine kinase inhibitors (TKIs) have traditionally been contraindicated owing to their teratogenicity. Management decisions should consider the risks to mother and foetus of uncontrolled disease and teratogenic medications. Further cases are required to build upon the paucity of current literature. We report 22 cases of CML diagnosed during pregnancy from 2002 to date. Twenty-one pregnancies resulted in healthy babies and one patient miscarried. Some patients remained untreated throughout pregnancy but the majority received one or both of interferon-α and leucapheresis. One patient was started on imatinib at Week 26, and one on hydroxycarbamide in the third trimester. We report haematological parameters during pregnancy to provide clinicians with realistic expectations of management. There were no fetal abnormalities related to treatment during pregnancy. Seventeen patients achieved at least major molecular response on first-line TKI. A diagnosis of CML during pregnancy can be managed without significant consequences for mother or child. Leucapheresis and interferon-α are generally safe throughout pregnancy. Despite having been avoided previously, there is growing evidence that certain TKIs may be used in particular circumstances during the later stages of pregnancy. Future work should aim to further elucidate this safety profile.

Keywords:  chronic myeloid leukaemia; pregnancy

DOI:  https://doi.org/10.1111/bjh.19491
Haematologica. 2024 May 02.

The initial molecular response predicts the deep molecular response but not treatment-free remission maintenance in a real-world chronic myeloid leukemia cohort.

Sandrine Saugues, Céline Lambert, Elisabeth Daguenet, Gabrielle Roth-Guepin, Françoise Huguet, Pascale Cony-Makhoul, Hyacinthe Johnson Ansah, Martine Escoffre-Barbe, Ali Turhan, Philippe Rousselot, Andreï Tchirkov, Dalil Hamroun, Eric Hermet, Bruno Pereira, Marc G Berger.

In chronic myeloid leukemia, the identification of early molecular predictors of stable treatment-free remission (TFR) after tyrosine kinase inhibitor (TKI) discontinuation is challenging. The predictive values of residual disease (BCR::ABL1 quantification) at months 3 and 6 and more recently, BCR::ABL1 transcript halving time (HT) have been described, but no study compared the predictive value of different early parameters. Using a real-world cohort of 408 patients, we compared the performance of the ELTS score, BCR::ABL1 HT, and residual disease at month 3 and 6 to predict the molecular response, achievement of the TKI discontinuation criteria, and TFR maintenance. The performances of BCR::ABL1 HT and residual disease at month 3 were similar. Residual disease at month 6 displayed the best performance for predicting the optimal response (area under the ROC curve between 0.81 and 0.92; cut-off values: 0.11% for MR4 at month 24 and 0.12% for MR4.5 at month 48). Conversely, no early parameter predicted reaching the TKI discontinuation criteria and TFR maintenance. We obtained similar results when patients were divided in subgroups by first-line treatment (imatinib vs second generation TKI, 2G-TKI). We identified a relationship between ELTS score, earlier milestones and TFR maintenance only in the 2G-TKI group. In conclusion, this first comparative study of early therapeutic response parameters showed that they are excellent indicators of TKI efficacy (BCR::ABL1 transcript reduction) and best responders. Conversely, they did not predict the achievement of the TKI discontinuation criteria and TFR maintenance, suggesting that other parameters are involved in TFR maintenance.

DOI: https://doi.org/10.3324/haematol.2023.284860
Br J Haematol. 2024 May 04.

Diagnosis of systemic mastocytosis with cryptic deletion of TET2 and DNMT3A resulting from unbalanced translocation.

Signy Chow, Stephanie Lee, August Lin, Kenneth J Craddock, Adam C Smith, Hubert Tsui.

  Systemic mastocytosis (SM) is a rare haematological neoplasm associated with the gain of function mutation KIT D816V in 90% of adult patients. Classically, cytogenetic aberrations are not common except in cases of SM associated with another haematological neoplasm. We highlight here an unusual clinical presentation of SM and demonstrate the utility of advanced cytogenetic analysis (optical genome mapping, OGM) in detecting a novel cytogenetic abnormality resulting in an unusual mechanism of DNMT3A and TET2 loss of function.

Keywords:  cancer cytogenetics; cytogenetic diagnosis; haematological malignancy; mastocytosis

DOI:  https://doi.org/10.1111/bjh.19501
Br J Haematol. 2024 May 02.

Autoimmune myelofibrosis: A Mayo Clinic series of 22 patients.

Naseema Gangat, Kaaren Reichard, Attilio Orazi, Ayalew Tefferi.

  We describe the clinical phenotype, management strategies and outcomes of 22 patients with autoimmune myelofibrosis (AIMF); median age: 45 years; 77% females; 83% with autoimmune disease, pancytopenia in 32% and transfusion-requiring anaemia in 59%. All informative cases were negative for JAK2 (n = 18) and CALR/MPL mutations (n = 12). Fourteen of nineteen (74%) evaluable patients achieved complete response (CR) based on the resolution of cytopenias. First-line treatments included steroids +/- immunosuppressive agents, cyclosporin and mycophenolate with CR in 7 of 13 (54%), 1 of 2 (50%) and 1 of 2 (50%) respectively. Rituximab salvage therapy yielded CR in 4 of 5 (80%) cases. The current study provides information on steroid-sparing treatments for AIMF.

Keywords:  JAK2; autoimmune; fibrosis; myeloproliferative

DOI:  https://doi.org/10.1111/bjh.19499
Nature. 2024 May 01.

Structural basis of lipid head group entry to the Kennedy pathway by FLVCR1.

Yeeun Son, Timothy C Kenny, Artem Khan, Kıvanç Birsoy, Richard K Hite.

Phosphatidylcholine and phosphatidylethanolamine, the two most abundant phospholipids in mammalian cells, are synthesized de novo by the Kennedy pathway from choline and ethanolamine, respectively1-6. Despite the essential roles of these lipids, the mechanisms that enable the cellular uptake of choline and ethanolamine remain unknown. Here we show that the protein encoded by FLVCR1, whose mutation leads to the neurodegenerative syndrome posterior column ataxia and retinitis pigmentosa7-9, transports extracellular choline and ethanolamine into cells for phosphorylation by downstream kinases to initiate the Kennedy pathway. Structures of FLVCR1 in the presence of choline and ethanolamine reveal that both metabolites bind to a common binding site comprising aromatic and polar residues. Despite binding to a common site, FLVCR1 interacts in different ways with the larger quaternary amine of choline in and with the primary amine of ethanolamine. Structure-guided mutagenesis identified residues that are crucial for the transport of ethanolamine, but dispensable for choline transport, enabling functional separation of the entry points into the two branches of the Kennedy pathway. Altogether, these studies reveal how FLVCR1 is a high-affinity metabolite transporter that serves as the common origin for phospholipid biosynthesis by two branches of the Kennedy pathway.

DOI: https://doi.org/10.1038/s41586-024-07374-4
Transfusion. 2024 May 01.

High CD34-positive cell dose in matched unrelated donor allogeneic hematopoietic stem cell transplant is not associated with graft-versus-host disease or mortality.

Zachary M Avigan, Ajoy L Dias, Laura E Dodge, Jon E Arnason, Robin M Joyce, Jessica Liegel, Jacalyn Rosenblatt, Matthew J Weinstock, David E Avigan, Richard L Haspel.

   BACKGROUND: CD34+ stem cells serve as the primary graft source for allogeneic transplants, with a minimum of 2-4 × 106 cells/kg needed for engraftment. There are conflicting data on outcomes at high stem cell doses, with studies limited by few patients receiving doses far above the minimum target.
STUDY DESIGN AND METHODS: In this retrospective, single-center study of patients with hematologic malignancies who underwent matched unrelated donor transplants, we assessed outcomes for engraftment, survival, relapse, and graft-versus-host disease (GVHD) for the highest CD34+ dose quintile (>13 × 106 cells/kg, n = 36) compared to the remaining patients (n = 139). Similar analysis was performed correlating T cell dose and outcomes.
RESULTS: There was no difference between the groups in neutrophil engraftment, with a trend toward faster platelet engraftment. There was no significant difference in mortality (adjusted risk ratio [aRR] = 1.02, 95% confidence interval [CI] = 0.85-1.22), relapse (aRR = 1.10, 95% CI = 0.85-1.42), or overall survival by Kaplan-Meier analysis (p = .44). High CD34+ dose was not associated with higher incidence of acute GVHD (aRR = 0.99 grades II-IV, aRR = 1.18 grades III-IV) or chronic GVHD (aRR = 0.87 overall, RR = 1.21 severe). There was limited correlation between CD34+ and T cell dose (R2 = .073), and there was no significant difference in survival, relapse, or GVHD in the highest T cell dose quintile (n = 33) compared to the remaining quintiles (n = 132).
DISCUSSION: We found no difference in survival, relapse, or GVHD incidence or severity in patients receiving CD34+ doses above prior cutoffs reported in the literature. These data do not support the routine use of graft CD34+ dose reduction.

Keywords:  acute GVHD; allogeneic hematopoietic stem cell transplant; chronic GVHD; high CD34+ cell dose; matched unrelated donor; transplant outcomes

DOI:  https://doi.org/10.1111/trf.17864