Bridging the gap: understanding contemporary autopsies in acute leukemia by comparing ante-mortem and post-mortem profiles.

This study investigates acute myeloid leukemia/lymphoblastic leukemia (AML/ALL) through a 14-year analysis (2009-2022) of 46 autopsied cases (age >12 years). B-ALL was the dominant subtype (34.8%). Liver and spleen were the common sites of active leukemia (63% cases). Symptoms like dyspnea and altered sensorium associated significantly with heart (p = .031) and brain leukostasis (p = .006). Measurable residual disease (MRD) negativity correlated with disease-free status outside the bone marrow, while MRD-positive cases displayed leukemic infiltrates. Infections were identified in 23 autopsied cases, notably linked to post-induction and post-transplant fatalities. Surprisingly, 18 of these 23 cases had unexpected infections mainly fungal (13 cases) with Aspergillus species as the most common. Diagnostic discrepancies were identified in 48% of cases. Malignant infiltration (46%) and infections (25%) were the leading causes of death. This research sheds light on leukemia in extra-medullary tissues, uncovers novel clinical-pathological associations, and highlights overlooked therapy side effects, offering insights for future case management.

PET/CT in the Evaluation of CAR-T Cell Immunotherapy in Hematological Malignancies.

Chimeric antigen receptor (CAR)-T cell-based immunotherapy has emerged as a path-breaking strategy for certain hematological malignancies. Assessment of the response to CAR-T therapy using quantitative imaging techniques such as positron emission tomography/computed tomography (PET/CT) has been broadly investigated. However, the definitive role of PET/CT in CAR-T therapy remains to be established. [18F]FDG PET/CT has demonstrated high sensitivity and specificity for differentiating patients with a partial and complete response after CAR-T therapy in lymphoma. The early therapeutic response and immune-related adverse effects such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome can also be detected on [18F]FDG PET images. In otherwise asymptomatic lymphoma patients with partial response following CAR-T therapy, the only positive findings could be abnormal PET/CT results. In multiple myeloma, a negative [18F]FDG PET/CT after receiving B-cell maturation antigen-directed CAR-T therapy has been associated with a favorable prognosis. In leukemia, [18F]FDG PET/CT can detect extramedullary metastases and treatment responses after therapy. Hence, PET/CT is a valuable imaging tool for patients undergoing CAR-T therapy for pretreatment evaluation, monitoring treatment response, assessing safety, and guiding therapeutic strategies. Developing guidelines with standardized cutoff values for various PET parameters and tumor cell-specific tracers may improve the efficacy and safety of CAR-T therapy.

Mixed-phenotype (B-lymphocytic/myeloid) acute leukemia with ETV6-ABL1 expression.

Objectives: Mixed-phenotype acute leukemia (MPAL) is rare in the clinic, accounting for approximately 2%-5% of acute leukemia cases. Methods: In this study the cohort included 126 patients, of which 125 cases were from re-examined published data and current patients from Shenzhen Longhua District Central Hospital, carrying an ETV6-ABL1 rearrangement from April 15, 2020 to December 19, 2020. The ETS variant transcription factor 6-Abelson proto-oncogene 1 (ETV6-ABL1) fusion gene is mainly seen in malignant hematological diseases such as acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), myeloproliferative neoplasms (MPNs). Positivity of both MPAL and ETV6-ABL1 suggest a poor prognosis. This is the first report of B lymphocytic/myeloid mixed-phenotype acute leukemia with ETV6-ABL1 fusion gene positivity. Complete remission was achieved with chemotherapy for lymphoid and myeloid leukemia and targeted therapy with tyrosine kinase inhibitors (TKIs). Results: The level of ETV6-ABL1/ABL decreased from 23.056% to 11.165%. After consolidation chemotherapy, the patient underwent allogeneic hematopoietic stem cell transplantation but died due to intestinal rejection. There are 126 cases of ETV6-ABL1 fusion gene transcript expression in numerous hematologic malignancies reported to date, including 48 cases of ALL, 12 of AML, and 65 of MPN. Eosinophilia is a common characteristic, especially in MPN patients. Conclusion: Survival analysis suggests that the survival time of ALL and MPN patients receiving TKI treatment is better than that of patients not receiving this treatment. Dasatinib or nilotinib, especially the former, is more effective than imatinib for MPN.

Acute myeloid leukemia with a novel AKAP9::PDGFRA fusion transformed from essential thrombocythemia: A case report and mini review.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. In this report, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors.

In Silico Drug Repurposing Against PSMB8 as a Potential Target for Acute Myeloid Leukemia Treatment.

PSMB8 emerges as a prominent gene associated with cancer survival, yet its potential therapeutic role in acute myeloid leukemia (AML) remains unexplored within the existing literature. The principal aim of this study is to systematically screen an expansive library of molecular entities, curated from various databases to identify the prospective inhibitory agents with an affinity for PSMB8. A comprehensive assortment of molecular compounds obtained from the ZINC15 database was subjected to molecular docking simulations with PSMB8 by using the AutoDock tool in PyRx (version 0.9.9) to elucidate binding affinities. Following the docking simulations, a select subset of molecules underwent further investigation through comprehensive ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis employing AdmetSar and SwissADME tools. Finally, RMSD, RMSF, Rg, and H bond analyses were conducted via GROMACS to determine the best conformationally dynamic molecule that represents the candidate agent for the study. Following rigorous evaluation, Adozelesin, Fiduxosin, and Rimegepant have been singled out based on considerations encompassing bioavailability scores, compliance with filter criteria, and acute oral toxicity levels. Additionally, ligand interaction analysis indicates that Adozelesin and Fiduxosin exhibit an augmented propensity for hydrogen bond formation, a factor recognized for its facilitative role in protein-ligand interactions. After final analyses, we report that Fiduxosin may offer a treatment possibility by reversing the low survival rates caused by PSMB8 high activation in AML. This study represents a strategic attempt to repurpose readily available pharmaceutical agents, potentially obviating the need for de novo drug development, and thereby offering promising avenues for therapeutic intervention in specific diseases.

Favorable Radiographic Response in a Patient With an Oligodendroglioma Treated With Azacitidine and Venetoclax for Acute Myeloid Leukemia.

The standard chemotherapy for treating oligodendrogliomas consists of a combination of procarbazine, lomustine, and vincristine (PCV). The combination of hypomethylating agents like azacitidine and BCL2 inhibitors like venetoclax has not been formally studied in the treatment of glial tumors. The combination of these two drugs is commonly used to treat acute myeloid leukemia (AML), with IDH-mutant disease being a particularly sensitive subtype. The use of azacitidine for the treatment of IDH-mutant gliomas has been reported in the literature, with mixed results that might suggest at least some benefits in a subtype of patients. It is also reported in the literature that the BCL2 gene is associated with treatment resistance and tumor recurrence in gliomas. Here, we present a patient with an oligodendroglioma who was treated with a conventional chemotherapy regimen for AML and, at the same time, had a favorable radiographic response to his brain tumor.

Human plasma cells engineered to secrete bispecifics drive effective in vivo leukemia killing.

Bispecific antibodies are an important tool for the management and treatment of acute leukemias. As a next step toward clinical translation of engineered plasma cells, we describe approaches for secretion of bispecific antibodies by human plasma cells. We show that human plasma cells expressing either fragment crystallizable domain-deficient anti-CD19 × anti-CD3 (blinatumomab) or anti-CD33 × anti-CD3 bispecific antibodies mediate T cell activation and direct T cell killing of B acute lymphoblastic leukemia or acute myeloid leukemia cell lines in vitro. We demonstrate that knockout of the self-expressed antigen, CD19, boosts anti-CD19-bispecific secretion by plasma cells and prevents self-targeting. Plasma cells secreting anti-CD19-bispecific antibodies elicited in vivo control of acute lymphoblastic leukemia patient-derived xenografts in immunodeficient mice co-engrafted with autologous T cells. In these studies, we found that leukemic control elicited by engineered plasma cells was similar to CD19-targeted chimeric antigen receptor-expressing T cells. Finally, the steady-state concentration of anti-CD19 bispecifics in serum 1 month after cell delivery and tumor eradication was comparable with that observed in patients treated with a steady-state infusion of blinatumomab. These findings support further development of ePCs for use as a durable delivery system for the treatment of acute leukemias, and potentially other cancers.

Epigenetic dysregulation in cancers by isocitrate dehydrogenase 2 (IDH2).

Recent advances in genome-wide studies have revealed numerous epigenetic regulations brought about by genes involved in cellular metabolism. Isocitrate dehydrogenase (IDH), an essential enzyme, that converts isocitrate into -ketoglutarate (KG) predominantly in the tricarboxylic acid (TCA) cycle, has gained particular importance due to its cardinal role in the metabolic pathway in cells. IDH1, IDH2, and IDH3 are the three isomeric IDH enzymes that have been shown to regulate cellular metabolism. Of particular importance, IDH2 genes are associated with several cancers, including gliomas, oligodendroglioma, and astrocytomas. These mutations lead to the production of oncometabolite D-2-hydroxyglutarate (D-2-HG), which accumulates in cells promoting tumor growth. The enhanced levels of D-2-HG competitively inhibit α-KG dependent enzymes, inhibiting cell TCA cycle, upregulating the cell growth and survival relevant HIF-1α pathway, promoting DNA hypermethylation related epigenetic activity, all of which synergistically contribute to carcinogenesis. The present review discusses epigenetic mechanisms inIDH2 regulation in cells and further its clinical implications.

[TCL1-family negative T-cell prolymphocytic leukemia with rapid progression of extranodal disease despite a normal white blood cell count].

Here we describe the case of a 69-year-old man who was found to have moderate thrombocytopenia and severe splenomegaly during a medical checkup at the age of 67. At the first visit, his white blood cell (WBC) count was 7,400/µl with 80% lymphocytes, and bone marrow aspiration showed 24% atypical lymphocytes. Flow cytometry of atypical lymphocytes was positive for mature T-cell markers, and T-cell clonality was revealed by T-cell receptor gene rearrangement. TCL1 was negative on immunohistochemistry. We diagnosed TCL1-family negative T-cell prolymphocytic leukemia (T-PLL) and employed watchful waiting. Thirty months after diagnosis, the patient developed urinary retention and right lower-limb paresis despite a normal WBC count, and an extradural tumor around the thoracic vertebrae and spinal cord compression were detected. The tumor was diagnosed as extranodal involvement of TCL1-family negative T-PLL, but the patient's general condition deteriorated rapidly, and no treatment was possible. T-PLL is a rare disease characterized by leukocytosis, and the WBC count generally increases with disease progression. Although blood counts are recommended for observation, it is important to keep in mind that the disease may worsen even if blood counts do not change.

[Successful remission induction with reduced-dose all-trans retinoic acid for acute promyelocytic leukemia complicated by COVID-19].

A 43-year-old man with pancytopenia was diagnosed with acute promyelocytic leukemia (APL). On the first day of induction therapy with all-trans retinoic acid (ATRA) alone, he presented with high fever and was found to have coronavirus disease 2019 (COVID-19) infection by SARS-CoV2 antigen test. While it is generally recommended to delay treatment for APL patients with COVID-19 unless urgent APL treatment is required, this patient needed to continue treatment due to APL-induced disseminated intravascular coagulation (DIC). Considering the challenge of distinguishing between differentiation syndrome (DS) and COVID-19 exacerbation, the ATRA dosage was reduced to 50%. The patient was able to continue treatment without development of DS or exacerbation of DIC, leading to his recovery from COVID-19 and remission of APL.

[Challenges of international collaborative clinical trials in Asia].

Clinical trials with a solid strategy are indispensable for improving outcomes of rare childhood leukemias such as infant acute lymphoblastic leukemia (ALL) and ALL associated with Down syndrome, and international collaboration contributes to trial success. I am part of a group conducting an international trial of ALL associated with Down syndrome in collaboration with Asian countries. Although we are meeting enrollment targets, there have been no enrollments outside Japan. We also planned a clinical trial in unclassifiable acute leukemia, but abandoned this effort due to a lack of consensus on the choice of treatment regimen. Many elements must fit together for an international trial to succeed, including not only the study's concept, theme, and objectives, but also the organization, the logistics, and, ultimately, trained professionals to carry it out. At the same time, of course, there is the need for appropriate timing and luck. International trials across countries with different cultures, social organizations, and medical systems require persistent effort and negotiation skills. Professional training and infrastructure development are necessary to make this possible.

[Experience with an international study on standard-risk relapsed childhood acute lymphoblastic leukemia (IntReALL SR 2010 study) in Japan].

Many effective new agents for relapsed childhood acute lymphoblastic leukemia (ALL) are now becoming available, and international standard chemotherapy should be developed to optimize use of these agents. Randomized controlled trials (RCTs) are needed to establish a standard treatment, but few have been conducted for relapsed childhood ALL in Japan due to the small patient population. Participation in international RCTs is necessary to access sufficient patients for informative study results, but differences in approved drugs and healthcare systems between countries make this challenging. In 2014, the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) participated in an international study on standard-risk relapsed childhood ALL (IntReALL SR 2010) involving two RCTs and multiple drugs not approved in Japan, which was addressed by replacing the unapproved drugs with alternative approved drugs with the same or similar efficacy. This article discusses the historical background of treatment development for relapsed childhood ALL, our experience in participating in the IntReALL SR 2010 trial, and prospects for treating relapsed childhood ALL.

Alemtuzumab monotherapy for T-cell prolymphocytic leukemia: an observational study in Japan.

Alemtuzumab is recommended as first-line and second-line therapies for T-cell prolymphocytic leukemia (T-PLL). This study retrospectively evaluated the efficacy and safety of alemtuzumab in nine Japanese patients with T-PLL at five participating institutions who were treated between January 2015 and August 2023. The median age at first administration of alemtuzumab was 72 years (range, 39 to 78). Two patients were treatment naïve, and seven had been treated with a median of one (range, 1 to 3) prior systemic therapy. Six patients were refractory to their most recent therapy. Three patients completed 12 weeks of treatment. The overall response rate and the complete response (CR) rate were 78% and 11%, respectively. Among the six patients who achieved a partial response, two achieved clinical CR but did not undergo bone marrow examination. One patient also achieved clinical CR but did not undergo CT or bone marrow examination for response evaluation. The median progression-free survival time was 8.1 months (95% confidence interval, 0.9 to 18.6). Three patients received readministration of alemtuzumab monotherapy after disease progression. There were no treatment-related deaths. The grade 3 or 4 nonhematologic adverse events included infusion reaction (grade 3, n = 2), cytomegalovirus reactivation (grade 3, n = 2), and pulmonary edema (grade 3, n = 1). One patient experienced Epstein‒Barr virus-positive diffuse large B-cell lymphoma 15 months after the last dose of alemtuzumab. These results confirm that the efficacy and safety of alemtuzumab monotherapy in Japanese patients are comparable to those previously reported.

A novel costimulatory molecule gene-modified leukemia cell-derived exosome enhances the anti-leukemia efficacy of DC vaccine in mouse models.

OBJECTIVES: Leukemia cell-derived exosomes (LEXs), carrying leukemia cell-specific antigens, can serve as a source of antigen for dendritic cell (DC) vaccine loading. However, LEX-targeted DC-based vaccines have demonstrated limited antitumor immune effects in clinical trials, attributed to the low immunogenicity of LEXs and the scant levels of costimulatory molecules on DCs. The costimulatory molecules CD80 and CD86, which are crucial to DC function, play a significant role in enhancing immune efficacy. In this study, we explored the anti-leukemia immune response of costimulatory molecule gene-modified LEX-targeted DCs (LEX-8086) in vitro and in animal models. METHODS: DCs were incubated with LEX-8086 to produce LEX-8086-targeted DCs (DCsLEX-8086). ELISA, cytotoxicity assays and flow cytometry utilized to assess the antitumor efficacy of DCsLEX8086 in vitro. Flow cytometry was used to evaluate the immunomodulatory function of DCsLEX8086 in animal models. RESULTS: Our findings indicated that LEX-8086 enhanced the maturation and antigen-presenting ability of DCs. Immunization with DCsLEX8086 significantly activated CD8+ T cells and boosted the CTL response in vitro. More importantly, DCsLEX-8086 effectively suppressed tumor growth and exerted anti-leukemia effects in both prophylactic and therapeutic animal models. Furthermore, DCsLEX-8086 promoted the proportion of CD4+ T cells, CD8+ T cells and M1 macrophages in the tumor environments both prophylactically and therapeutically. Treatment with DCsLEX-8086 showed no significant difference in the levels of M2 macrophages but decreased the proportion of Tregs within the tumor bed during therapeutic experiments. CONCLUSION: The results suggested that DCsLEX-8086 induces a more effective anti-leukemia immunity compared to DCsLEX-null in vivo and in vitro. DCsLEX-8086 might achieve antitumor effects by elevating the numbers of CD4+ T cells, CD8+ T cells, and M1 macrophages in tumors. Our findings indicate that DCsLEX-8086 could be leveraged to develop a new, highly effective vaccine for anti-leukemia immunity.

Cancer-related cognitive impairment in older adults with acute myeloid leukemia treated with hypomethylating agents and venetoclax chemotherapy: a longitudinal descriptive study.

PURPOSE: To explore cancer-related cognitive impairment (CRCI) in older adults with acute myeloid leukemia (AML) receiving venetoclax in combination with hypomethylating agents or low-dose cytarabine chemotherapy. METHODS: This study is a longitudinal, qualitative descriptive study. Participants were recruited using purposive sampling. Semi-structured interviews were conducted among 11 older adults with AML at cycle 2, cycle 4, and cycle 7 of chemotherapy. An early end-of-study interview was conducted for those who changed treatment plans during the study follow-up. RESULTS: A total of 22 transcripts were included for thematic analysis. Four themes emerged: (1) CRCI experiences, (2) impact of CRCI, (3) CRCI coping strategies, and (4) perceived CRCI-related factors. Older adults with AML experienced challenges in memory, language, and attention both intermittently and daily. These cognitive changes impacted their emotion, daily activities, social connection, and their caregivers' responsibilities. Hence, these older adults with AML developed problem-solving and emotional coping strategies to cope with CRCI. Older adults with AML also identified demographic, physiology/clinical, psychological, and other factors that might contribute to CRCI. CONCLUSION: This study offers important insight for clinicians to understand how older adults with AML experience CRCI and how it impacts their daily routines. It indicates that clinicians should ask patients about their experience with cognitive changes at each encounter to provide support or coping strategies as needed to prevent CRCI from further hindering their quality of life.

A Lipid-Sensitive Spider Peptide Toxin Exhibits Selective Anti-Leukemia Efficacy through Multimodal Mechanisms.

Anti-cancer peptides (ACPs) represent a promising potential for cancer treatment, although their mechanisms need to be further elucidated to improve their application in cancer therapy. Lycosin-I, a linear amphipathic peptide isolated from the venom of Lycosa singorensis, shows significant anticancer potential. Herein, it is found that Lycosin-I, which can self-assemble into a nanosphere structure, has a multimodal mechanism of action involving lipid binding for the selective and effective treatment of leukemia. Mechanistically, Lycosin-I selectively binds to the K562 cell membrane, likely due to its preferential interaction with negatively charged phosphatidylserine, and rapidly triggers membrane lysis, particularly at high concentrations. In addition, Lycosin-I induces apoptosis, cell cycle arrest in the G1 phase and ferroptosis in K562 cells by suppressing the PI3K-AKT-mTOR signaling pathway and activating cell autophagy at low concentrations. Furthermore, intraperitoneal injection of Lycosin-I inhibits tumor growth of K562 cells in a nude mouse xenograft model without causing side effects. Collectively, the multimodal effect of Lycosin-I can provide new insights into the mechanism of ACPs, and Lycosin-I, which is characterized by high potency and specificity, can be a promising lead for the development of anti-leukemia drugs.

Acute myeloid leukemia (AML) with chromosome 3 inversion: biology, management, and clinical outcome.

Acute myeloid leukemia (AML) is a complex hematological malignancy characterized by diverse genetic alterations, each with distinct clinical implications. Chromosome 3 inversion (inv(3)) is a rare genetic anomaly found in approximately 1.4-1.6% of AML cases, which profoundly affects prognosis. This review explores the pathophysiology of inv(3) AML, focusing on fusion genes like GATA2::EVI1 or GATA2::MECOM. These genetic rearrangements disrupt critical cellular processes and lead to leukemia development. Current treatment modalities, including intensive chemotherapy (IC), hypomethylating agents (HMAs) combined with venetoclax, and allogeneic stem cell transplantation are discussed, highlighting outcomes achieved and their limitations. The review also addresses subgroups of inv(3) AML, describing additional mutations and their impact on treatment response. The poor prognosis associated with inv(3) AML underscores the urgent need to develop more potent therapies for this AML subtype. This comprehensive overview aims to contribute to a deeper understanding of inv(3) AML and guide future research and treatment strategies.

Additive antitumor effect of arsenic trioxide with exposure to ionizing radiation to human acute promyelocytic leukemia HL­60 cells.

Arsenic trioxide (ATO) is expected to be a chemical drug with antitumor activity against acute promyelocytic leukemia (APL), a type of acute myeloid leukemia. In Japan, its antitumor effects were confirmed in clinical trials for APL, and it has been approved in various countries around the world. However, there have been no reports on ATO's antitumor effects on radioresistant leukemia cells, which can be developed during radiotherapy and in combination with therapeutic radiation beams. The present study sought to clarify the antitumor effect of ATO on APL cells with radiation resistance and determine its efficacy when combined with ionizing radiation (IR). The radiation­resistant HL60 (Res­HL60) cell line was generated by subjecting the native cells to 4­Gy irradiation every week for 4 weeks. The half­maximal inhibitory concentration (IC50) for cell proliferation by ATO on native cell was 0.87 µM (R2=0.67), while the IC50 for cell proliferation by ATO on Res­HL60 was 2.24 µM (R2=0.91). IR exposure increased the sub­G1 and G2/M phase ratios in both cell lines. The addition of ATO resulted in a higher population of G2/M after 24 h rather than 48 h. When the rate of change in the sub­G1 phase was examined in greater detail, the sub­G1 phase in both control cells without ATO significantly increased by exposure to IR at 24 h, but only under the condition of 2 Gy irradiation, it had continued to increase at 48 h. Res­HL60 supplemented with ATO showed a higher rate of sub­G1 change at 24 h; however, 2 Gy irradiation resulted in a decrease compared with the control. There was a significant increase in the ratio of the G2/M phase in cells after incubation with ATO for 24 h, and exposure to 2 Gy irradiation caused an even greater increase. To determine whether the inhibition of cell proliferation and cell cycle disruptions is related to reactive oxygen species (ROS) activity, intracellular ROS levels were measured with a flow cytometric assay. Although the ROS levels of Res­HL60 were higher than those of native cells in the absence of irradiation, they did not change after 0.5 or 2 Gy irradiation. Furthermore, adding ATO to Res­HL60 reduced intracellular ROS levels. These findings provide important information that radioresistant leukemia cells respond differently to the antitumor effect of ATO and the combined effect of IR.

Cardiotoxicity of CPX-351 in children and adolescents with relapsed AML: a Children's Oncology Group report.

Introduction: Anthracyclines are effective in treating acute myeloid leukemia (AML) but limited by cardiotoxicity. CPX-351, a liposomal daunorubicin and cytarabine, may provide therapeutic benefit with less cardiotoxicity. Acute changes in left ventricular systolic function and cardiac biomarkers were evaluated after a cycle of CPX-351 in children with relapsed AML treated on the phase 1/2 Children's Oncology Group study, AAML1421. Methods: Subjects received 135 units/m2/dose of CPX-351 on days 1, 3, and 5 as cycle 1. Echocardiograms were performed and centrally quantitated at baseline and at the end of cycle 1 (day 29 +/- 1 week). High sensitivity troponin (hs-cTnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were measured at baseline and serially through the end of cycle 1 (days 5, 8, 15, 22 and 29). Differences between baseline and post-CPX-351 echo/biomarker measures were analyzed using Wilcoxon signed rank tests. Linear regression was used to model post-CPX-351 left ventricular ejection fraction (LVEF) with cTnT/NT-proBNP at each time point, controlling for baseline LVEF. Cancer therapy related cardiac dysfunction (CTRCD) was defined as a decline in LVEF of ≥10%-<50%. Results: Twenty-five of 38 heavily anthracycline pre-treated (median 348 mg/m2 daunorubicin equivalents) subjects enrolled on AAML1421 were included in the cardiac analyses. At baseline, centrally quantitated LVEF was <50% in 8 of 25 subjects (32%) with a median LVEF of 53.8% [48.0, 56.9]. Following CPX-351, LVEF declined significantly (ΔLVEF -3.3% [-7.8, 0]) and 6 of 25 subjects (24%) experienced CTRCD. Amongst all subjects, hs-cTnT was modestly increased at end of cycle 1 compared to baseline [baseline hs-cTnT 7.2 (3, 10.6); ΔcTnT 1.80 (0, 6.1), p = 0.03]. NT-proBNP remained stably elevated without significant change. No significant associations were seen between NT-proBNP or cTnT levels and post-CPX-351 LVEF. Discussion: In this single arm study of anthracycline pre-treated children exposed to CPX-351, baseline abnormalities in cardiovascular function were prevalent. Following CPX-351, LVEF decreased, cTnT increased, and NT-proBNP did not change. Longer follow-up is needed to determine whether these changes result in clinically meaningful long-term decrements in cardiac function. An ongoing randomized trial of CPX-351 compared to standard anthracyclines in anthracycline naïve patients will provide further insight into the cardiac effects of CPX-351 (ClinicalTrials.gov; NCT04293562).