Poor prognosis of SRSF2 gene mutations in patients treated with VEN-AZA for newly diagnosed acute myeloid leukemia.

Mutations in spliceosome genes (SRSF2, SF3B1, U2AF1, ZRSR2) correlate with inferior outcomes in patients treated with intensive chemotherapy for Acute Myeloid Leukemia. However, their prognostic impact in patients treated with less intensive protocols is not well known. This study aimed to evaluate the impact of Spliceosome mutations in patients treated with Venetoclax and Azacitidine for newly diagnosed AML. 117 patients treated in 3 different hospitals were included in the analysis. 34 harbored a mutation in at least one of the spliceosome genes (splice-mut cohort). K/NRAS mutations were more frequent in the splice-mut cohort (47% vs 19%, p=0.0022). Response rates did not differ between splice-mut and splice-wt cohorts. With a median follow-up of 15 months, splice mutations were associated with a lower 18-month LFS (p=0.0045). When analyzing splice mutations separately, we found SRSF2 mutations to be associated with poorer outcomes (p=0.034 and p=0.037 for OS and LFS respectively). This negative prognostic impact remained true in our multivariate analysis. We believe this finding should warrant further studies aimed at overcoming this negative impact.

Caspase-2 protects against ferroptotic cell death.

Caspase-2, one of the most evolutionarily conserved members of the caspase family, is an important regulator of the cellular response to oxidative stress. Given that ferroptosis is suppressed by antioxidant defense pathways, such as that involving selenoenzyme glutathione peroxidase 4 (GPX4), we hypothesized that caspase-2 may play a role in regulating ferroptosis. This study provides the first demonstration of an important and unprecedented function of caspase-2 in protecting cancer cells from undergoing ferroptotic cell death. Specifically, we show that depletion of caspase-2 leads to the downregulation of stress response genes including SESN2, HMOX1, SLC7A11, and sensitizes mutant-p53 cancer cells to cell death induced by various ferroptosis-inducing compounds. Importantly, the canonical catalytic activity of caspase-2 is not required for its role and suggests that caspase-2 regulates ferroptosis via non-proteolytic interaction with other proteins. Using an unbiased BioID proteomics screen, we identified novel caspase-2 interacting proteins (including heat shock proteins and co-chaperones) that regulate cellular responses to stress. Finally, we demonstrate that caspase-2 limits chaperone-mediated autophagic degradation of GPX4 to promote the survival of mutant-p53 cancer cells. In conclusion, we document a novel role for caspase-2 as a negative regulator of ferroptosis in cells with mutant p53. Our results provide evidence for a novel function of caspase-2 in cell death regulation and open potential new avenues to exploit ferroptosis in cancer therapy.

Venetoclax Resistance in Acute Myeloid Leukemia.

Venetoclax is a BH3-mimetics agent interacting with the anti-apoptotic protein BCL2, facilitating cytochrome c release from mitochondria, subsequent caspases activation, and cell death. Venetoclax combined with azacitidine (VEN-AZA) has become a new standard treatment for AML patients unfit for intensive chemotherapy. In the phase III VIALE-A study, VEN-AZA showed a 65% overall response rate and 14.7 months overall survival in comparison with 22% and 8 months in the azacitidine monotherapy control arm. Despite these promising results, relapses and primary resistance to venetoclax are frequent and remain an unmet clinical need. Clinical and preclinical studies have been conducted to identify factors driving resistance. Among them, the most documented are molecular alterations including IDH, FLT3, TP53, and the newly described BAX mutations. Several non-genetic factors are also described such as metabolic plasticity, changes in anti-apoptotic protein expression, and dependencies, as well as monocytic differentiation status. Strategies to overcome venetoclax resistance are being developed in clinical trials, including triplet therapies with targeted agents targeting IDH, FLT3, as well as the recently developed menin inhibitors or immunotherapies such as antibody-drug conjugated or monoclonal antibodies. A better understanding of the molecular factors driving venetoclax resistance by single-cell analyses will help the discovery of new therapeutic strategies in the future.

Peripheral blood haploidentical hematopoietic cell transplantation for patients aged 70 years and over with acute myeloid leukemia or high-risk myelodysplastic syndrome.

Haploidentical stem cell transplantation (Haplo-SCT) using non-myeloablative conditioning regimen (NMAC) has extended the feasibility of allogeneic transplantation, notably in older patients. However, there is few data specifically focusing on patients aged 70 years and over with AML and MDS. Thus the benefit of transplantation in this population is still debated. Here we report our single center experience of peripheral blood Haplo-SCT with NMAC and post-transplantation cyclophosphamide in AML and MDS patients aged 70 years and over. We analyzed 50 patients (27 AML, 23 MDS) with a median age of 72 years (70-77), 12/50 (24%) with active disease at Haplo-SCT. Cumulative incidence of grade 3-4 acute and moderate or severe chronic GVHD were 6% and 25%, respectively. Non-relapse mortality (NRM) at day +100 was 0%. NRM, relapse, PFS and OS at 3 years were 16%, 18%, 66%, and 69%, respectively. Among patients who were disease free at 2 years post Haplo-SCT, 88% are living without immunosuppressive treatment. Peripheral blood Haplo-SCT is feasible in selected AML/MDS patients over 70 years, without any early NRM. It produces long-term disease control and survival. Thus, age by itself should not be considered as a formal barrier to Haplo-SCT.

Downregulation of stromal syntenin sustains AML development.

The crosstalk between cancer and stromal cells plays a critical role in tumor progression. Syntenin is a small scaffold protein involved in the regulation of intercellular communication that is emerging as a target for cancer therapy. Here, we show that certain aggressive forms of acute myeloid leukemia (AML) reduce the expression of syntenin in bone marrow stromal cells (BMSC). Stromal syntenin deficiency, in turn, generates a pro-tumoral microenvironment. From serial transplantations in mice and co-culture experiments, we conclude that syntenin-deficient BMSC stimulate AML aggressiveness by promoting AML cell survival and protein synthesis. This pro-tumoral activity is supported by increased expression of endoglin, a classical marker of BMSC, which in trans stimulates AML translational activity. In short, our study reveals a vicious signaling loop potentially at the heart of AML-stroma crosstalk and unsuspected tumor-suppressive effects of syntenin that need to be considered during systemic targeting of syntenin in cancer therapy.

Erythroleukemia: Classification.

Acute erythroid leukemia (AEL) is a rare (2%-5%) form of acute myeloid leukemia (AML). Molecular alterations found in AEL resemble those of other AMLs. We report a classification of AELs in three major classes, with different prognosis and some specific features such as a tendency to mutual exclusion of mutations in epigenetic regulators and signaling genes.

Targeting regulated cell death pathways in acute myeloid leukemia.

The use of the BCL2 inhibitor venetoclax has transformed the management of patients with acute myeloid leukemia (AML) who are ineligible for intensive chemotherapy. By triggering intrinsic apoptosis, the drug is an excellent illustration of how our greater understanding of molecular cell death pathways can be translated into the clinic. Nevertheless, most venetoclax-treated patients will relapse, suggesting the need to target additional regulated cell death pathways. To highlight advances in this strategy, we review the recognized regulated cell death pathways, including apoptosis, necroptosis, ferroptosis and autophagy. Next, we detail the therapeutic opportunities to trigger regulated cell death in AML. Finally, we describe the main drug discovery challenges for regulated cell death inducers and their translation into clinical trials. A better knowledge of the molecular pathways regulating cell death represents a promising strategy to develop new drugs to cure resistant or refractory AML patients, particularly those resistant to intrinsic apoptosis.

FMS-Like Tyrosine Kinase 3 Inhibitors in the Treatment of Acute Myeloid Leukemia: An Update on the Emerging Evidence and Safety Profile.

FMS-like tyrosine kinase 3 (FLT3) is one of the most frequently mutated genes in acute myeloid leukemia (AML). Approximately 30% of the adult cases harbor an internal tandem duplication (FLT3-ITD) and 5-10% a tyrosine kinase domain (TKD) amino acid substitution (FLT3-TKD). The treatment paradigm of AML patients harboring FLT3 mutations (30%) has been modified by the discovery of tyrosine kinase inhibitors. First- and second-generation inhibitors classify FLT3 inhibitors according to FLT3 specificity: first-generation FLT3 inhibitors include sorafenib and midostaurin and second-generation inhibitors are represented by quizartinib, gilteritinib and crenolanib, among others. Activity of these inhibitors depends on their mechanism of receptor binding (active vs inactive conformation) and efficacy against the FLT3-ITD and -TKD mutations (type 1 inhibitors are active both on FLT3-ITD and TKD, whereas type 2 inhibitors are active only on FLT3-ITD). The FLT3 inhibitors sorafenib, midostaurin, quizartinib and gilteritinib have been tested in monotherapy in several settings including refractory or relapsed AML (R/R AML), post-transplant maintenance as well as in combination with intensive chemotherapy (ICT) or non-intensity regimens. The results of published randomized studies support the use of sorafenib in a post-transplant setting (SORMAIN trial), midostaurin in combination with ICT based (RATIFY trial) and gilteritinib for R/R AML (ADMIRAL trial). Gilteritinib in combination with hypomethylating agent as well as quizartinib are not supported by solid randomized trial results for their use in FLT3-mutated AML patients.

Therapy-related Myeloid Neoplasms Following PARP Inhibitors: Real-life Experience.

PURPOSE: To provide insights into the diagnosis and management of therapy-related myeloid neoplasms (t-MN) following PARP inhibitors (PARPi). EXPERIMENTAL DESIGN: In a French cancer center, we identified and described the profiles of 13 t-MN diagnosed among 37 patients with ovarian cancer referred to hematology consultation for cytopenia under PARPi. Next, we described these 13 t-MN post-PARPi among 37 t-MN post ovarian cancer according to PARPi exposure. Finally, we described 69 t-MN post-PARPi in a national cohort. RESULTS: From 2016 to 2021, cumulative incidence of t-MN was 3.5% (13/373) among patients with ovarian cancer treated with PARPi. At time of hematologic consultation, patients with t-MN had a longer PARPi exposure (9 vs. 3 months, P = 0.01), lower platelet count (74 vs. 173 G/L, P = 0.0005), and more cytopenias (2 vs. 1, P = 0.0005). Compared with t-MN not exposed to PARPi, patients with t-MN-PARPi had more BRCA1/2 germline mutation (61.5% vs. 0%, P = 0.03) but similar overall survival (OS). In the national cohort, most t-MN post-PARPi had a complex karyotype (61%) associated with a high rate of TP53 mutation (71%). Median OS was 9.6 months (interquartile range, 4-14.6). In multivariate analysis, a longer time between end of PARPi and t-MN (HR, 1.046; P = 0.02), olaparib compared with other PARPi (HR, 5.82; P = 0.003) and acute myeloid leukemia (HR, 2.485; P = 0.01) were associated with shorter OS. CONCLUSIONS: In a large series, we described a high incidence of t-MN post-PARPi associated with unfavorable cytogenetic and molecular abnormalities leading to poor OS. Early detection is crucial, particularly in cases of delayed cytopenia.

Inhibition of the CtBP complex and FBXO11 enhances MHC class II expression and anti-cancer immune responses.

There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.

Azacitidine Plus Venetoclax for the Treatment of Relapsed and Newly Diagnosed Acute Myeloid Leukemia Patients.

Venetoclax (VEN) belongs the BH3-mimetic class that selectively targets BCL-2, activating apoptosis. The combination of VEN and azacitidine (AZA) has changed the paradigm of treatment of newly diagnosed (ND) acute myeloid leukemia (AML) patients ineligible for intensive chemotherapy. There is scarce evidence for the use of VEN-AZA for relapsed or refractory (R/R) AML. We compared the outcome of 39 R/R AML and 38 ND AML patients treated between 01/20 and 12/21. The median age was 69 (22-86) and 73 (61-81) in the R/R and ND groups, respectively. Adverse cytogenetics were found in 36% of patients in the R/R group and 59% of patients in the ND group. Overall response rate was 37% in R/R AML, including 13% CR, 8% CRi, 3% PR and 13% MLFS, and 58% in the ND AML, including 32% CR, 13% CRi and 13% MLFS. Adverse cytogenetics was associated with treatment failure in the R/R group (Relative Risk = 0.13, p = 0.005). Median overall survival (OS) was 5.9 months in the R/R group and 9.4 months in the ND group. Median OS was 2.2 months in the adverse cytogenetics group versus 8.7 months in the intermediate cytogenetics group in the R/R group (p = 0.02). Median leukemia-free survival was not different between the two groups (9.4 months and 10.3 months), indicating that VEN-AZA can be an efficient salvage treatment for selected R/R AML patients. In conclusion, VEN-AZA is a promising treatment for ND AML and for selected R/R AML patients.

Bendamustine-EAM versus R-BEAM after high-dose cytarabine-based induction in newly diagnosed patients with mantle cell lymphoma, a LYSA retrospective study.

Cytarabine-based immuno-chemotherapy followed by autologous stem cell transplantation (ASCT) consolidation is standard of care for fit patients with Mantle Cell Lymphoma (MCL). BEAM (Carmustine, Etoposide, Aracytine, Melphalan) is among the most frequently used conditioning regimen. Studies comparing BEAM with Bendamustine-EAM (BeEAM) have suggested that patients treated with BeEAM have a better progression-free survival (PFS). We performed a cross-study analysis to better evaluate BeEAM. Thirty-five patients from a retrospective study who received R-DHAP/BeEAM were compared to 245 patients from the LyMa trial (NCT00921414) who all received R-DHAP followed by R-BEAM. PFS and Overall Survival (OS) were estimated using Kaplan-Meier methods. At 2 years there was no difference between R-BEAM and BeEAM in either PFS (84.9% versus 87.9%; p = 0.95) or OS (91.8% versus 94.2%; p = 0.30). Analyses were repeated on a propensity score to reduce biases. Each patient from the BeEAM cohort (n = 30) was matched to three patients from the R-BEAM cohort (n = 90) for age, sex, MIPI score, pre-transplant status disease and rituximab maintenance (RM). PFS and OS at 2 years remained similar between R-BEAM and BeEAM with more renal toxicity in BeEAM group. MCL patients who received R-DHAP induction before ASCT have similar outcome after R-BEAM or BeEAM conditioning regimen.

Pharmacologic Reduction of Mitochondrial Iron Triggers a Noncanonical BAX/BAK-Dependent Cell Death.

Cancer cell metabolism is increasingly recognized as providing an exciting therapeutic opportunity. However, a drug that directly couples targeting of a metabolic dependency with the induction of cell death in cancer cells has largely remained elusive. Here we report that the drug-like small-molecule ironomycin reduces the mitochondrial iron load, resulting in the potent disruption of mitochondrial metabolism. Ironomycin promotes the recruitment and activation of BAX/BAK, but the resulting mitochondrial outer membrane permeabilization (MOMP) does not lead to potent activation of the apoptotic caspases, nor is the ensuing cell death prevented by inhibiting the previously established pathways of programmed cell death. Consistent with the fact that ironomycin and BH3 mimetics induce MOMP through independent nonredundant pathways, we find that ironomycin exhibits marked in vitro and in vivo synergy with venetoclax and overcomes venetoclax resistance in primary patient samples. SIGNIFICANCE: Ironomycin couples targeting of cellular metabolism with cell death by reducing mitochondrial iron, resulting in the alteration of mitochondrial metabolism and the activation of BAX/BAK. Ironomycin induces MOMP through a different mechanism to BH3 mimetics, and consequently combination therapy has marked synergy in cancers such as acute myeloid leukemia. This article is highlighted in the In This Issue feature, p. 587.

Venetoclax in Acute Myeloid Leukemia: Molecular Basis, Evidences for Preclinical and Clinical Efficacy and Strategies to Target Resistance.

Venetoclax is a BH3-mimetics agent specifically interacting with the antiapoptotic protein BCL-2, facilitating cytochrome c release from mitochondria, subsequent caspases activation, and cell death. Utilization of venetoclax has profoundly changed the landscape of treatment for the poor-prognosis category of AML patients unfit for intensive chemotherapy. In the phase III VIALE-A study, Venetoclax, in combination with the hypomethylating agent azacitidine, showed a 65% overall response rate and 14.7-month overall survival, in comparison with 22% and 8 months in the control arm. These results led to the widespread use of venetoclax in this indication. Other combination regimens, consisting of low-intensity, intensive, or targeted therapies are currently under evaluation. Despite promising results, preventing relapses or resistance to venetoclax is still an unmet clinical need. Numerous studies have been conducted to identify and overcome venetoclax resistance in preclinical models or in clinical trials, including the inhibition of other antiapoptotic proteins, the induction of proapoptotic BH3-only proteins, and/or the targeting of the mitochondrial metabolism and machinery.

Analysis of a large single institution cohort of related donors fails to detect a relation between SDF1/CXCR4 or VCAM/VLA4 genetic polymorphisms and the level of hematopoietic progenitor cell mobilization in response to G-CSF.

We studied a cohort of 367 healthy related donors who volunteered to donate their hematopoietic stem cells for allogeneic transplantation. All donors were homogeneously cared for at a single institution, and received rhG-CSF as a mobilization treatment prior to undergoing apheresis. Peripheral blood CD34+ cell counts were used as the main surrogate marker for rhG-CSF induced mobilization. We searched whether inter-individual variations in known genetic polymorphisms located in genes whose products are functionally important for mobilization, could affect the extent of CD34+ mobilization, either individually or in combination. We found little or no influence of individual SNPs or haplotypes for the SDF1, CXCR4, VCAM and VLA4 genes, whether using CD34+ cell counts as a continuous or a categorical variable. Simple clinical characteristics describing donors such as body mass index, age and possibly sex are more potent predictors of stem cell mobilization. The size of our cohort remains relatively small for genetic analyses, however compares favorably with cohorts analyzed in previously published reports suggesting associations of genetic traits to response to rhG-CSF; notwithstanding this limitation, our data do not support the use of genetic analyses when the choice exists of several potential donors for a given patient.

Bendamustine-EAM versus BEAM regimen in patients with mantle cell lymphoma undergoing autologous stem cell transplantation in the frontline setting: a multicenter retrospective study from Lymphoma Study Association (LYSA) centers.

The combination of carmustine, etoposide, cytarabine, and melphalan (BEAM) as conditioning regimen prior to autologous stem-cell transplantation (ASCT) remains the standard of care for patients with mantle cell lymphoma (MCL) who are eligible for transplantation. The replacement of carmustine with bendamustine (BeEAM) was described as a promising alternative in non-Hodgkin lymphoma. The aim of this retrospective study was to compare the BeEAM with the BEAM regimen in MCL patients in the frontline setting. Sixty and 108 patients were included in the BeEAM and the BEAM groups, respectively. At 3 years, progression-free survival (PFS) was significantly higher in the BeEAM than in the BEAM group (84% [73-96] vs. 63% [51-79], p = 0.03). The overall survival was not statistically different between the two groups (p = 0.2). In multivariable analysis, BeEAM regimen remained associated with higher PFS (HR = 0.377, 95% CI, 0.146-0.970; p = 0.043). Subgroup analyses in patients treated with prior rituximab-aracytine induction alone showed that BeEAM improved the PFS compared with BEAM regimen (p = 0.04). Despite the high rate of acute renal failure KDIGO III (32%), treatment-related mortality was not increased with the BeEAM regimen. A prospective randomized trial will be necessary to confirm the beneficial effect of the BeEAM regimen in MCL patients undergoing ASCT.