Efficacy of combination of venetoclax with azacitidine or chemotherapy in refractory/relapse acute leukemias of ambiguous lineage, not otherwise specified

Acute leukemia of ambiguous lineage: Diagnosis, prognosis and treatment

Acute leukemias of ambiguous lineage (ALAL) are an infrequent subtype of acute leukemias without clear evidence of differentiation to a one single cell lineage. Despite their rarity constitute a recognized subgroup in the recent international classifications, such as the WHO (World Health Organization) classification. Their diagnosis require highly specialized flow cytometry technology, and also cytogenetics and molecular techniques. The low frequency of the disease has made it difficult to find the best therapeutic strategy, due both to the lack of prospective studies and randomized trials, and to the heterogeneity of the published retrospective studies on follow-up and treatment. The group of ALAL has bad prognosis, and usually requires intensive strategies that include consolidation with allogeneic stem cell transplant as part of the treatment. The objective of this review was to analyze diagnosis, treatment and prognosis of this rare subtype of leukemias.

[Efficacy and safety analysis of venetoclax in combination with multidrug chemotherapy in patients with newly diagnosed acute leukemia of ambiguous lineage]

Objective: To evaluate the efficacy and safety of venetoclax in combination with multidrug chemotherapy in patients with newly diagnosed acute leukemia of ambiguous lineage (ALAL) . Methods: A retrospective analysis of clinical data was performed on patients with newly diagnosed ALAL who were hospitalized at Jiangsu Provincial People's Hospital from June 2021 to July 2024. Of the 13 patients who received initial induction therapy with venetoclax combined with multidrug chemotherapy, 8 received VAA+P regimen, and 5 received V+IA regimen. Patients with FLT3 mutation were treated with FLT3 inhibitor, and Ph(+) patients received an additional tyrosine kinase inhibitor. Overall survival (OS), disease-free survival (DFS), and adverse events were analyzed. Results: According to the World Health Organization 5th edition of the classification of hematolymphoid tumors, the immunophenotypes were T/myeloid mixed-phenotype acute leukemia (MPAL) (n=4), B/myeloid MPAL (n=7), and ALAL- not otherwise specified (n=2). Of the seven patients with B/myeloid MPAL, four were Ph(+) and belonged to the group with specific gene abnormalities of ALAL. Three patients had FLT3 mutation (one with FLT3-TKD mutation and two with FLT3-ITD mutation). Prior to the second course of consolidation therapy, the efficacy of venetoclax induction therapy was evaluated, and a complete response rate of 100% was achieved in 13 patients. In the subsequent consolidation therapy phase, one patient discontinued treatment and was lost to follow-up; nine patients underwent allogeneic hematopoietic stem cell transplantation, four of whom died due to posttransplant complications and five achieved DFS. Of the three patients (≥70 years old) who received consolidation therapy as before, two achieved DFS and one died due to central nervous system leukemia. The median OS time was not reached in 13 patients; the 75th percentile survival time was 12.0 months, with a 12-month cumulative survival rate of 64.5%. The median DFS time was not reached in all patients; the 75th percentile DFS time was 8.2 months, with a 12-month cumulative DFS rate of 67.1%. All patients experienced grade 3 or 4 hematologic toxicity, including neutropenia and thrombocytopenia, during and after induction therapy. All patients recovered hematopoietic function after the initial induction therapy, with no fatal hemorrhage, tumor lysis syndrome, neurological adverse events, or grade 3 or higher organ toxicity, excluding preexisting conditions. Conclusion: Venetoclax in combination with multidrug chemotherapy was effective and associated with tolerable adverse reactions in patients with newly diagnosed ALAL.

Case report: Venetoclax plus Azacitidine in treatment of acute undifferentiated leukemia

OBJECTIVES

Acute undifferentiated leukemia (AUL) is a clinical rare leukemia with an overall poor prognosis. Currently, there are no well-established treatment guidelines for AUL, further exploration of optimal treatment options is now required.

METHODS

We report an AUL patient who was complicated by a NRAS mutation and del5q was admitted to our hospital and we present the clinical features. In addition, we conducted a literature review.

RESULTS

The "VA" scheme combines agents Venetoclax and Azacitidine that have synergistic therapeutic effect with a tolerable safety profile. There is no previous report of the "VA" scheme employed in AUL treatment. An AUL patient who was complicated by a NRAS mutation and del5q was admitted to our hospital. The "VA" scheme was administrated, and complete remission (CR) was achieved at the end of the first cycle. The patient then underwent HLA-identical sibling allogeneic hematopoietic stem cell transplantation.

DISCUSSION

The "VA" scheme has been extensively used in AML treatment, but its application in AUL treatment has not yet been reported. This study is the first to report an AUL patient treated with the "VA" scheme and achieved CR. Our result preliminarily suggested the effectiveness and safety of the "VA" scheme in AUL treatment, but validation is required in more clinical samples. The "VA" scheme provides a new treatment option for AUL patients and deserves further clinical promotion.

Successful treatment of a B/T MPAL patient by chemo-free treatment with venetoclax, azacitidine, and blinatumomab

B/T mixed phenotype acute leukemia (MPAL), which represents only 2-3% of all MPAL cases, is classified as a high-risk leukemia subtype. Adults diagnosed with B/T MPAL have a notably low 3-year survival rate, estimated at 20-40%. The rarity and undercharacterization of B/T MPAL present substantial challenges in identifying an optimal treatment protocol. This report aims to shed light on this issue by presenting a case in which a patient with a complex karyotype was treated using a combination of venetoclax, azacitidine, and blinatumomab. This novel, chemo-free regimen resulted in the patient achieving both hematologic and molecular complete remission, with no severe organ or hematological toxicity observed. Notably, the patient continued to maintain molecular remission for 1 year following the transplantation. Based on these findings, the combination of venetoclax, azacitidine, and blinatumomab could be considered a potential therapeutic approach for B/T MPAL patients, meriting further investigation.

[Update on acute leukemia of ambiguous lineage in 2023 - Recommendations of the French Society for Childhood and Adolescent Cancer and Leukemia (SFCE)]

Acute leukemias of ambiguous lineage (ALAL) represent between 3 and 5% of childhood AL. This term encompasses many subtypes of AL that have been defined according to the immunophenotypic profile based on the expression of various lineage markers. This classification has been modified and enriched during the last decade thanks to the improvement of molecular biology techniques, which have led to reconsider the ontogenic proximity existing between certain forms of ALAL. This increasing diagnostic complexity justifies the establishment of a close communication between clinicians and biologists in the management of these rare forms of AL. Indeed, the initial classification remains the cornerstone of their management since it conditions the future choice of therapeutic protocol. Thus, with the notable exception of undifferentiated forms of AL or AUL (for acute undetermined leukemia), it is now accepted that ALAL benefit from a lymphoid-based therapy approach. As with the management of "classic" acute lymphoblastic leukemias (ALL), the evaluation of response to treatment will determine the modalities of therapeutic intensification. The objective of improving the prognosis of ALAL justifies, in the long term, their future inclusion in the international ALLTogether protocol while continuing in-depth molecular exploration of these patients to identify targeted therapies.

Mixed-Phenotype Acute Leukemia: Clinical Diagnosis and Therapeutic Strategies

Mixed-phenotype acute leukemia (MPAL) comprises a heterogenous group of leukemias that are genetically, immunophenotypically, and clinically, diverse. Given the rarity of the disease, the diagnosis and treatment of MPAL is extremely challenging. Recent collaborative efforts have made significant progress in understanding the complex genomic landscape of MPAL. Some retrospective studies support starting ALL-type induction followed by an allogeneic stem cell transplant(allo-sct) in the first complete remission; however, due to the inherent bias of retrospective data and small case series, a prospective validation of AML- and ALL-based regimen, and the incorporation of targeted therapies based on genetics and immunophenotype are warranted. The prognosis of adults and children with MPAL varies; this justifies modulating the intensity of therapy, including the use of allo-sct as a consolidation strategy.

Progress in understanding the mechanisms of resistance to BCL-2 inhibitors

Venetoclax is a new type of BH3 mimetic compound that can target the binding site in the BCL-2 protein and induce apoptosis in cancer cells by stimulating the mitochondrial apoptotic pathway. Venetoclax is especially used to treat haematological malignancies. However, with the recent expansion in the applications of venetoclax, some cases of venetoclax resistance have appeared, posing a major problem in clinical treatment. In this article, we explored several common mechanisms of venetoclax resistance. Increased expression of the antiapoptotic proteins MCL-1 and BCL-XL plays a key role in conferring cellular resistance to venetoclax. These proteins can bind to the released BIM in the context of venetoclax binding to BCL-2 and thus continue to inhibit mitochondrial apoptosis. Structural mutations in BCL-2 family proteins caused by genetic instability lead to decreased affinity for venetoclax and inhibit the intrinsic apoptosis pathway. Mutation or deletion of the BAX gene renders the BAX protein unable to anchor to the outer mitochondrial membrane to form pores. In addition to changes in BCL-2 family genes, mutations in other oncogenes can also confer resistance to apoptosis induced by venetoclax. TP53 mutations and the expansion of FLT3-ITD promote the expression of antiapoptotic proteins MCL-1 and BCL-XL through multiple signalling pathways, and interfere with venetoclax-mediated apoptosis processes depending on their affinity for BH3-only proteins. Finally, the level of mitochondrial oxidative phosphorylation in venetoclax-resistant leukaemia stem cells is highly abnormal. Not only the metabolic pathways but also the levels of important metabolic components are changed, and all of these alterations antagonize the venetoclax-mediated inhibition of energy metabolism and promote the survival and proliferation of leukaemia stem cells. In addition, venetoclax can change mitochondrial morphology independent of the BCL-2 protein family, leading to mitochondrial dysfunction. However, mitochondria resistant to venetoclax antagonize this effect, forming tighter mitochondrial cristae, which provide more energy for cell survival.

Mixed Phenotype/Lineage Leukemia: Has Anything Changed for 2021 on Diagnosis, Classification, and Treatment?

Purpose of Review

Recent advances in the small field of the rare mixed phenotype acute leukemias (MPAL) are presented focusing on a better understanding of their pathophysiology and search for better therapeutic approaches.

Recent Findings

Three aspects of respective classification, therapy, and immunophenotype of MPAL are reviewed. New proposals have been made to segregate MPAL subtypes based on their genomic landscape. In parallel, it was found that a large array of therapeutic approaches has been tested in the past few years with increasingly good results. Finally, we explored the use of unsupervised flow cytometry analysis to dissect subtle variations in markers expression to better characterize the variegating aspect of MPALs.

Summary

Genomic and immunophenotypic aspects more clearly link MPAL subtypes with bona fide acute myeloblastic of lymphoblastic leukemias. This is likely to impact therapeutic strategies, towards a better management and outcome.