Young patients with myelofibrosis have distinct clinicomolecular features, favorable prognosis, and commonly exhibit inflammatory comorbidities.

Myelofibrosis (MF) is commonly diagnosed in older individuals and has not been extensively studied in young patients. Given the infrequent diagnosis in young patients, analyzing this cohort may identify factors that predict for disease development/progression. We retrospectively analyzed clinical/genomic characteristics, treatments, and outcomes of patients with MF aged 18-50 years (YOUNG) at diagnosis. Sixty-three YOUNG patients were compared to 663 patients diagnosed at 51 or older (OLDER). YOUNG patients were more likely to be female, harbor driving CALR mutations, lack splicing gene mutations, and have low-risk disease by dynamic international prognostic scoring system (DIPSS) at presentation. Thirty-six patients (60%) presented with incidental lab findings and 19 (32%) with symptomatic disease. Median time to first treatment was 9.4 months (mo). Fourteen (22%) YOUNG patients underwent allogeneic hematopoietic stem cell transplant (median 57.4 mo post-diagnosis). Five (8%) developed blast-phase disease (median 99 mo post-diagnosis). Median overall survival (OS) for YOUNG patients was not reached compared to 62.8 mo in OLDER cohort (p < 0.001). The survival advantage for YOUNG patients lost significance when compared to OLDER patients lacking splicing mutations (p = 0.11). Thirty-one (49%) had comorbidities predating MF diagnosis. Presence of a comorbidity correlated with increased disease risk as measured by serial DIPSS (p=0.02). Increased disease risk correlated with decreased OS (p = 0.05). MF is rare in young adults, has distinct clinical/molecular correlates, and a favorable prognosis. The high frequency of inflammatory comorbidities and their correlation with progression of disease risk clinically highlights the role of inflammation in MF pathogenesis.

Drivers of deep molecular response and long-term outcomes in patients with core binding factor acute myeloid leukemia.

A swimmer plot on clinical course of patients undergoing allogeneic stem cell transplant for core binding factor acute myeloid leukemia.

Disease-related thrombocytopenia in myelofibrosis is defined by distinct genetic etiologies and is associated with unique prognostic correlates.

BACKGROUND: Thrombocytopenia in patients with myelofibrosis (MF) is prognostically detrimental and poses a therapeutic challenge. MF patients with thrombocytopenia are considered high-risk by most prognostic models and their distinct phenotype has given rise to the emerging concept of cytopenic MF. Yet, the mechanisms underlying thrombocytopenia in MF are poorly understood. METHODS: This study aimed to highlight the genetic mechanisms driving low platelet counts in treatment-naive MF patients, establish their phenotypic correlates, and assess prognostic factors specific to this group of patients. RESULTS: The authors found that most patients presenting with low platelets had a clear thrombocytopenia-specific genetic abnormality involving a U2AF1 Q157 mutation, deletion 20q, molecular complexity (three or more mutations), or high-risk karyotype. Etiologic clustering did not correlate with prognosis; however, thrombocytopenic patients were found to have unique prognostic variables including low serum albumin and mutations of SRSF2 and TP53. This led to the proposal of a prognostic model (SRSF2, albumin, TP53 score) that stratifies thrombocytopenic patients as low, intermediate, or high-risk with corresponding median survivals of 93.5, 29.5, and 7.2 months, respectively. CONCLUSIONS: This study demonstrates that thrombocytopenia in MF is driven by different genetic mechanisms and is not uniformly high-risk. As novel agents with improved hematologic safety profiles enter the treatment landscape, thoughtful, risk-adapted therapeutic decisions will be required for MF patients with thrombocytopenia. LAY SUMMARY: A significant minority of patients with myelofibrosis (MF) present with low platelets. Historically, these patients have been viewed as having "high-risk" disease, but this may not be uniformly true. Our study shows that there are various different causes for low platelets in MF, some of which represent high-risk disease whereas others do not. Additionally, our study shows that genetic mutations affecting the genes SRSF2 and TP53 are uniquely problematic in this group, as is a low serum albumin level. This study helps to risk-stratify MF patients with thrombocytopenia, thereby providing more information to guide informed and individualized treatment decisions.

Clonal selection in therapy-related myelodysplastic syndromes and acute myeloid leukemia under azacitidine treatment.

INTRODUCTION: Therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML) are defined as complications of previous cytotoxic therapy. Azacitidine (AZA), a hypomethylating agent, has showed activity in t-MDS/AML. OBJECTIVES: We evaluated the clonal dynamics of AZA-treated t-MDS/AML. METHODS: We collected bone marrow samples, at diagnosis and during treatment, from AZA-treated t-MDS/AML patients. NGS on 19 myeloid genes was performed, and candidate mutations with a variant allele frequency >5% were selected. RESULTS: Seven t-AML and 12 t-MDS were included with median age of 71 (56-82) years old, median number of AZA cycles of 6 (1-15), and median overall survival (OS) of 14 (3-29) months. We observed correlation between AZA response and clonal selection. Decrease of TP53-mutated clone was correlated with response to AZA, confirming AZA efficacy in this subgroup. In some patients, emergence of mutations was correlated with progression or relapse without impact on OS. Clones with mutations in genes for DNA methylation regulation frequently occurred with other mutations and remained stable during AZA treatment, independent of AZA response. CONCLUSION: We confirmed that the molecular complexity of t-MNs and that the follow-up of clonal selection during AZA treatment could be useful to define treatment combination.

Validation of the Khorana score in acute myeloid leukemia patients: a single-institution experience.

BACKGROUND: Although patients with acute myeloid leukemia (AML) were shown to have an increased risk of thrombosis, no thrombosis risk assessment scoring system has been developed for AML patients. The Khorana Risk Score (KRS), which has been widely used for thrombosis risk assessment in the clinical setting, was developed on the basis of solid tumor data and has not been validated among AML patients. This study aims to validate the use of the KRS as a thrombosis risk-scoring system among patients with AML. METHODS: Using data from H. Lee Moffitt Cancer Center and Research Institution's Total Cancer Care Research Study, we retrospectively identified patients who were histologically confirmed with AML from 2000 to 2018. Clinical and laboratory variables at the time of AML diagnosis were characterized and analyzed. The thrombotic event rate was estimated with the Kaplan-Meier method and compared using the log-rank test. RESULTS: A total of 867 AML patients were included in the analysis. The median age at AML diagnosis was 75 years (range, 51-96), and the majority were male (65%, n = 565). A total of 22% (n = 191), 51% (n = 445), 24% (n = 207), and 3% (n = 24) of patients had a KRS of 0, 1, 2, and 3, respectively. A total of 42 thrombotic events (3% [n = 6/191] with a KRS of 1; 5% [n = 23/445] with a KRS of 2; 6.3% [n = 13/207] with a KRS of 3) were observed, with a median follow-up of 3 months (range, 0.1-307). There was no statistical difference in the risk of thrombosis between these groups (P = .1949). CONCLUSIONS: Although there was an increased risk of thrombosis associated with a higher KRS among AML patients with a KRS of 1 to 3, the difference was not statistically significant. Furthermore, only a few patients were found to have a KRS > 3, and this was largely due to pancytopenia, which is commonly associated with AML. These results indicate the need for a better thrombotic risk-scoring system for AML patients.

Cost-effectiveness of anticoagulants for suspected heparin-induced thrombocytopenia in the United States.

Despite the availability of multiple nonheparin anticoagulants for the treatment of heparin-induced thrombocytopenia (HIT), few data are available comparing the cost-effectiveness of these agents. This analysis is particularly important when considering differences in the risk of adverse effects, routes of administration, requirements for phlebotomy and laboratory monitoring, and overall drug costs. We conducted a cost-effectiveness analysis of argatroban, bivalirudin, and fondaparinux for the treatment of suspected HIT from the institutional perspective. A 3-arm decision-tree model was developed that employs standard practices for anticoagulation monitoring. We incorporated published data on drug efficacy and probability of HIT-related thromboembolism and major bleeding. We considered both institutional costs and average wholesale price (AWP) and performed probabilistic sensitivity analyses (PSA) to address any uncertainty in model parameters. Using institutional costs, fondaparinux prevailed over both argatroban and bivalirudin in terms of cost ($151 vs $1250 and $1466, respectively) and adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). Results were consistent when AWP was used, with fondaparinux being less expensive ($555 vs $3081 and $2187, respectively) and more effective in terms of adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). The PSA confirmed our findings using both institutional costs and AWP. In conclusion, fondaparinux subcutaneous injection afforded significant advantages in terms of cost savings and adverse events averted compared with IV argatroban or bivalirudin infusions. Our data strongly suggest potential cost savings with fondaparinux and underscore the critical need for larger clinical studies of fondaparinux in the treatment of suspected HIT.

4EBP1/c-MYC/PUMA and NF-κB/EGR1/BIM pathways underlie cytotoxicity of mTOR dual inhibitors in malignant lymphoid cells.

The mammalian target of rapamycin (mTOR), a kinase that regulates proliferation and apoptosis, has been extensively evaluated as a therapeutic target in multiple malignancies. Rapamycin analogs, which partially inhibit mTOR complex 1 (mTORC1), exhibit immunosuppressive and limited antitumor activity, but sometimes activate survival pathways through feedback mechanisms involving mTORC2. Thus, attention has turned to agents targeting both mTOR complexes by binding the mTOR active site. Here we show that disruption of either mTOR-containing complex is toxic to acute lymphocytic leukemia (ALL) cells and identify 2 previously unrecognized pathways leading to this cell death. Inhibition of mTORC1-mediated 4EBP1 phosphorylation leads to decreased expression of c-MYC and subsequent upregulation of the proapoptotic BCL2 family member PUMA, whereas inhibition of mTORC2 results in nuclear factor-κB-mediated expression of the Early Growth Response 1 (EGR1) gene, which encodes a transcription factor that binds and transactivates the proapoptotic BCL2L11 locus encoding BIM. Importantly, 1 or both pathways contribute to death of malignant lymphoid cells after treatment with dual mTORC1/mTORC2 inhibitors. Collectively, these observations not only provide new insight into the survival roles of mTOR in lymphoid malignancies, but also identify alterations that potentially modulate the action of mTOR dual inhibitors in ALL.

Role of Maintenance Therapy after High-Dose Chemotherapy and Autologous Hematopoietic Cell Transplantation in Aggressive Lymphomas: A Systematic Review.

Significant uncertainty exists in regard to the efficacy of maintenance therapy after high-dose chemotherapy (HDC) as well as autologous stem cell transplantation (ASCT) for the treatment of patients with aggressive lymphoma. A systematic review was performed to evaluate the effectiveness of post-ASCT maintenance therapy in patients with relapsed/refractory lymphoma. A comprehensive literature search yielded 4476 studies and a total of 42 studies (11 randomized controlled trials [RCT], 9 retrospective comparative studies, and 22 single-arm studies) were included in the systematic review. There was significant heterogeneity in study design, chemotherapeutic regimens, post-ASCT maintenance strategies, patient enrollment criteria, and study endpoints. Our findings suggest that post-ASCT maintenance immune-targeting strategies, including PD-1/PD-L1 blocking antibodies, rituximab, and brentuximab, may improve progression-free survival but not overall survival. Collectively, the results indicate a need for testing new strategies with well-designed and adequately powered RCTs to better address the role of post-ASCT maintenance in relapsed/refractory lymphomas.

Outcome Comparison of Allogeneic versus Autologous Stem Cell Transplantation in Transformed Low-Grade Lymphoid Malignancies: A Systematic Review and Pooled Analysis of Comparative Studies.

BACKGROUND: Some patients with low-grade lymphoid malignancies develop transformed disease, requiring stem cell transplantation (SCT). SCT outcomes in transformed low-grade lymphoid malignancies may differ from those of nontransformed disease or other aggressive non-Hodgkin lymphomas. We conducted a pooled analysis of the clinical outcomes of allogeneic versus high-dose therapy (HDT) with autologous SCT in adult patients with transformed low-grade lymphoid malignancies. METHODS: A PubMed, EMBASE, and Cochrane search yielded 4 comparative studies reporting allogeneic versus HDT with autologous SCT outcomes in adults (age ≥18) with transformed low-grade lymphoid malignancies, including follicular, chronic/small lymphocytic, and marginal zone lymphoma. Risk ratio (RR) and 95% CI were calculated using random-effects models. RESULTS: Rates for overall survival (OS) were 51.0 versus 69.5% (RR = 1.55, 95% CI 1.19-2.02, p = 0.001), rates of relapse were 37.3 versus 35.3% (RR = 1.04, 95% CI 0.70-1.55, p = 0.84), and rates of transplant-related mortality (TRM) were 33.3 versus 7.2% (RR = 4.52, 95% CI 2.75-7.43, p < 0.00001) for allogeneic versus autologous SCT. Previous rituximab treatment, reduced intensity conditioning regimen prior to SCT, or original pathology had no prognostic impact. CONCLUSION: HDT followed by autologous SCT was associated with lower TRM and a better OS, but there was no difference in relapse versus allogeneic SCT. Autologous SCT may be the better therapeutic option, considering the second chance of allogeneic SCT in the case of relapse.

Cardioprotective role of ß-blockers and angiotensin antagonists in early-onset anthracyclines-induced cardiotoxicity in adult patients: a systematic review and meta-analysis.

BACKGROUND: Anthracyclines are commonly used chemotherapeutic agents with proven efficacy in such malignancies as breast cancer, Hodgkin and non-Hodgkin lymphomas. These agents are associated with irreversible accumulative dose-related cardiomyopathy. Many agents have been examined to reduce cardiotoxicity risk. AIMS: We performed a systematic review and meta-analysis to determine the efficacy of ß-blockers and angiotensin antagonists to prevent early-onset anthracyclines-induced left ventricular dysfunction and cardiac events. METHODS: Relevant articles were searched in PubMed, EMBASE and Cochrane database of systematic reviews up to July 2015. Eligible studies were limited to randomised controlled trials comparing the efficacy of cardioprotective agents (ß-blocker and angiotensin antagonist) with control (either no treatment or placebo) in adult patients (age >18 years) treated with anthracyclines-based regimens. RESULTS: Pooled analysis showed an association of ß-blockers and/or angiotensin antagonists treatment with higher post-chemotherapy left ventricular ejection fraction (LVEF) of 64.03% compared with 57.48% for control treatment. The mean difference estimate (95% CI) was 6.06% (0.54 to 11.58), p=0.03, with significant heterogeneity, I(2) (95% CI)=96% (82.7 to 109.3). Though the point estimate for the relative rate of cardiac events was lower in the experimental arm, the difference was not statistically significant. In an exploratory subgroup analysis, the benefit of experimental agents on LVEF preservation was prominent in patients treated with higher accumulative dose of anthracyclines, but not in the lower dose group. CONCLUSIONS: ß-Blockers and angiotensin antagonists treatments were associated with better LVEF preservation, and the benefit was prominent in patients treated with higher anthracyclines accumulative dose. Unexplained heterogeneity remains, indicating the need for more controlled studies. This analysis provides some support for the routine use of ß-blockers or angiotensin antagonists in patients undergoing anthracyclines treatment, especially when higher accumulative dose is expected.

Farnesyltransferase inhibitor tipifarnib inhibits Rheb prenylation and stabilizes Bax in acute myelogenous leukemia cells.

Although farnesyltransferase inhibitors have shown promising activity in relapsed lymphoma and sporadic activity in acute myelogenous leukemia, their mechanism of cytotoxicity is incompletely understood, making development of predictive biomarkers difficult. In the present study, we examined the action of tipifarnib in human acute myelogenous leukemia cell lines and clinical samples. In contrast to the Ras/MEK/ERK pathway-mediated Bim upregulation that is responsible for tipifarnib-induced killing of malignant lymphoid cells, inhibition of Rheb-induced mTOR signaling followed by dose-dependent upregulation of Bax and Puma occurred in acute myelogenous leukemia cell lines undergoing tipifarnib-induced apoptosis. Similar Bax and Puma upregulation occurred in serial bone marrow samples harvested from a subset of acute myelogenous leukemia patients during tipifarnib treatment. Expression of FTI-resistant Rheb M184L, like knockdown of Bax or Puma, diminished tipifarnib-induced killing. Further analysis demonstrated that increased Bax and Puma levels reflect protein stabilization rather than increased gene expression. In U937 cells selected for tipifarnib resistance, neither inhibition of signaling downstream of Rheb nor Bax and Puma stabilization occurred. Collectively, these results not only identify a pathway downstream from Rheb that contributes to tipifarnib cytotoxicity in human acute myelogenous leukemia cells, but also demonstrate that FTI-induced killing of lymphoid versus myeloid cells reflects distinct biochemical mechanisms downstream of different farnesylated substrates. (ClinicalTrials.gov identifier NCT00602771).

Transcriptional Plasticity Drives IMiD and p300 Inhibitor Resistance in Multiple Myeloma.

SUMMARY: In this issue of Blood Cancer Discovery, Neri, Barwick, and colleagues and Welsh, Barwick, and colleagues performed RNA sequencing, chromatin immunoprecipitation sequencing, assay for transposase-accessible chromatin using sequencing, and genetic studies to characterize the underlying mechanisms of immunomodulatory drug (IMiD) resistance in multiple myeloma. They demonstrated that IMiD resistance is driven by sustained expression of MYC and IRF4 via transcriptional plasticity that involves induction of ETV4 and BATF proteins, the binding of these proteins to their super-enhancers, and the recruitment of BRD4 and p300. Finally, these studies suggest IMiD and p300 inhibitor combination as a promising therapeutic strategy in multiple myeloma. See related article by Neri, Barwick, et al., p. 56 (9). See related article by Welsh, Barwick, et al., p. 34 (10).

Triple-Negative Myelofibrosis: Disease Features, Response to Treatment and Outcomes.

BACKGROUND: Myelofibrosis is the most aggressive subtype among classical BCR::ABL1 negative myeloproliferative neoplasms. About 90% of cases are driven by constitutive activation of 1 of 3 genes impacting the JAK/STAT pathway: JAK2, CALR, and MPL. Triple-negative myelofibrosis (TN-MF) accounts for only 5%-10% of cases and carries the worst outcomes. Little has been described about this subset of disease. Given the marked heterogeneity surrounding disease biology, clonal architecture, clinical presentation, and poor outcomes in TN-MF, identification of features of interest and assessment of treatment response are areas in need of further investigation. PATIENTS AND METHODS: We collected and evaluated baseline clinical and molecular parameters from 626 patients with a diagnosis of myelofibrosis who presented to the H. Lee Moffitt Cancer Center in Tampa (Florida, US) between 2003 and 2021 and compared them based on presence or absence of the three classical phenotypic driver mutations. RESULTS: A small proportion of patients (6%) harbored TN-MF which correlated with inferior outcomes, marked by a 4-year reduction in overall survival time compared to the non-TN cohort (mOS 37.4 months vs. 85.7 months; P = .009) and higher rates of leukemic transformation. More pronounced thrombocytopenia and anemia, lower LDH, EPO levels, as well as lower percentage of marrow blasts at baseline were more commonly seen in TN-MF (P < .05). Similarly, patients with TN-MF had higher risk disease per DIPSS+ and GIPSS. Mutations impacting RNA splicing, epigenetic modification and signaling, specifically SRSF2, SETBP1, IDH2, CBL, and GNAS, were more commonly seen among those lacking a classical phenotypic driver. The prevalence of co-mutant ASXL1/SRSF2 clones was significantly higher in TN-MF as was trisomy 8. TN patients had fewer responses (46.2% vs. 63.4%) and shorter duration of response to ruxolitinib. CONCLUSION: TN-MF is invariably associated with significantly decreased survival and more aggressive clinical behavior with higher rates of leukemic transformation and shorter duration of response to ruxolitinib. Mutations impacting RNA splicing, epigenetic modification and signaling (SRSF2, SETBP1, IDH2, CBL, and GNAS) are more common in TN-MF, which likely drive its aggressive course and may account for suboptimal responses to JAK inhibition.

Mutations highly specific for secondary AML are associated with poor outcomes in ELN favorable risk NPM1-mutated AML.

ABSTRACT: Acute myeloid leukemia (AML) is a heterogeneous malignancy with outcomes largely predicted by genetic abnormalities. Mutations of NPM1 are common in AML, occurring in ∼30% of cases, and generally considered a favorable risk factor. Mutations highly specific for secondary AML (sMut) have been shown to confer poor prognosis, but the overall impact of these mutations in the setting of favorable-risk AML defined by mutant NPM1 remains unclear. In this multicenter study of patients with AML (n = 233) with NPM1 mutation at diagnosis, we observed that patients with sMut had worse overall survival (OS) than those without sMut (15.3 vs 43.7 months; P = .002). Importantly, this finding persisted in the European LeukemiaNet (ELN) 2017-defined favorable risk subset (14.7 months vs not reached; P < .0001). Among patients who achieved NPM1 measurable residual disease (MRD) negativity, longer OS was observed in the entire cohort (P = .015) as well as in both the sMut subset (MRD negative: median OS (mOS) 73.9 months vs MRD positive: 12.3 months; P = .0170) and sMut ELN 2017-favorable subset (MRD negative: mOS 27.3 vs MRD positive: 10.5 months; P = .009). Co-occurrence of sMut and mutant NPM1 confers a poor prognosis in AML.

Trisomy 8 Defines a Distinct Subtype of Myeloproliferative Neoplasms Driven by the MYC-Alarmin Axis.

Despite advances in understanding the genetic abnormalities in myeloproliferative neoplasms (MPNs) and the development of JAK2 inhibitors, there is an urgent need to devise new treatment strategies, particularly for triple negative myelofibrosis (MF) patients who lack mutations in the JAK2 kinase pathway and have very poor clinical outcomes. Here we report that MYC copy number gain and increased MYC expression frequently occur in triple negative MF, and that MYC-directed activation of S100A9, an alarmin protein that plays pivotal roles in inflammation and innate immunity, is necessary and sufficient to drive development and progression of MF. Notably, the MYC-S100A9 circuit provokes a complex network of inflammatory signaling that involves numerous hematopoietic cell types in the bone marrow microenvironment. Accordingly, genetic ablation of S100A9 or treatment with small molecules targeting the MYC-S100A9 pathway effectively ameliorates MF phenotypes, highlighting the MYC-alarmin axis as a novel therapeutic vulnerability for this subgroup of MPNs.

Clinicopathologic characteristics, genetic features, and treatment options for acute lymphoblastic leukemia with JAK2 rearrangement-A 10-case study and literature review.

JAK2 rearrangement (JAK2-R) in acute lymphoblastic leukemia (ALL) is rare and often categorized as B-ALL with BCR::ABL1-like features based on the World Health Organization classification. We report 10 patients with JAK2-R ALL, 9 males and 1 female, with a median age 40.5 years. Eight patients presented with marked leukocytosis (median WBC, 63 × 10 9/L) and hypercellular (>95%) bone marrow with increased lymphoblasts (72%-95%). There was no evidence of bone marrow fibrosis or hypereosinophilia. Immunophenotypic analysis showed 9 B-cell and 1 T-cell neoplasms. Using fluorescence in situ hybridization (FISH) and RNA sequencing analysis, JAK2 partners were identified for 7 cases and included PCM1 (n = 4), ETV6 (n = 2) and BCR (n = 1). All patients received upfront polychemotherapy. Additionally, 2 patients received ruxolitinib, 2 received allogeneic stem cell transplant, and 1 received CAR-T therapy. The 1- and 3-year overall survival rates were 55.6% and 22.2%, respectively. A literature review identified 24 B-ALL and 4 T-ALL cases with JAK2-R reported, including 16 males, 6 females and 6 gender not stated. Many JAK2 partner-genes were reported with the most common being PAX5 (n = 7), ETV6 (n = 5), BCR (n = 4) and PCM1 (n = 2). Survival data on 13 reported cases showed 1- and 3-year overall survival rates of 41.7% and 41.7%, respectively. In summary, JAK2-R ALL occurs more often in adult males, are mostly of B-cell lineage, and associated with an aggressive clinical course. Absence of eosinophilia and bone marrow fibrosis and no evidence of preexisting/concurrent JAK2-R myeloid neoplasms distinguish JAK2-R ALL from other myeloid/lymphoid neoplasms with eosinophilia and JAK2-R.

Clinical Response to Upfront Targeted Tyrosine Kinase Inhibitors among Patients with Myeloid/Lymphoid Neoplasms with Eosinophilia and Tyrosine Kinase Gene Fusion.

INTRODUCTION: Myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusion (MLN-TK) is an entity encompassed of a heterogeneous group of rare hematopoietic neoplasms that are driven by gene fusion involving PDGDRA/B, FGFR1, JAK2, FLT3 or ETV6::ABL1. Though patients presenting with chronic phase MLN-TK with PDGFRA fusion display a favorable outcome in response to upfront TK inhibitor (TKI) therapy, the outcomes of MLNs driven by other TK fusions are not well described. In this study, we aimed to critically analyze the treatment outcomes of patients with MLN-TK, focusing on the role of upfront TKIs in both chronic- and blast-phase diseases. METHODS: The retrospective study included patients with confirmed MLN-TK from 3 centers and assessed demographic and clinical variables, treatment, and outcomes. RESULTS: Forty-two patients with confirmed MLN-TK [PDGFRA (n = 22), PDGFRB (n = 4), FGFR1(n = 10), JAK2 (n = 2); and FLT3 (n = 3)] were included. Fifteen of 25 (60%) chronic-phased patients received upfront TKI therapy had a long-term remission. Nine of 16 (60%) blast-phase patients with upfront TKIs also achieved complete remission and remained alive at a median follow-up of 20 months. All 3 patients with blast phase disease who received upfront chemotherapy without positive response did not respond to subsequent TKI therapy, emphasizing the importance of initiating TKI therapy early. Upfront TKI therapy was associated with longer overall survival in univariate analyses (HR, 0.054 [95% CI, 0.007-0.42]) and multivariate analyses (HR, 0.03 [95% CI, 0.002-0.47]). CONCLUSION: The outcomes of upfront TKI therapy are excellent for MLN-TK in both chronic and blast phases, regardless of gene abnormalities.

Gilteritinib Combined with Azacitidine as Salvage Therapy for B/Myeloid Mixed Phenotype Acute Leukemia.

Mixed phenotype acute leukemia (MPAL) is a rare group of acute leukemias with blasts that co-express antigens of more than one lineage or separate populations of blasts of different lineages. Though treatment guidelines are not well established, the standard of care in treating MPAL remains the acute lymphoblastic leukemia (ALL)-derived chemotherapeutic regimen of hyper-cyclophosphamide, vincristine, doxorubicin (also known by its trade name, Adriamycin), and dexamethasone (CVAD) followed by allogeneic stem-cell transplant (ASCT). Beyond induction chemotherapy, evidence-based treatments remain to be investigated, especially regarding patients who relapse prior to ASCT. This case report illustrates a patient with relapsed MPAL following induction hyper-CVAD who was not immediately eligible for ASCT. After brief treatment with gilteritinib alone, the patient was started on gilteritinib and azacitidine as salvage therapy and achieved and maintained complete remission with incomplete count recovery (CRi) for eight months. Targeted therapy is a novel approach to improve survival rate, but unfortunately, there have been very few studies in the context of MPAL. We report a patient with relapsed FLT3-mutant MPAL who achieved remission using a combination approach with targeted therapy.