The treatment of acute promyelocytic leukemia in 2023: Paradigm, advances, and future directions

Higher TIGIT+ γδ TCM cells may predict poor prognosis in younger adult patients with non-acute promyelocytic AML

Introduction

γδ T cells recognize and exert cytotoxicity against tumor cells. They are also considered potential immune cells for immunotherapy. Our previous study revealed that the altered expression of immune checkpoint T-cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) on γδ T cells may result in immunosuppression and is possibly associated with a poor overall survival in acute myeloid leukemia (AML). However, whether γδ T-cell memory subsets are predominantly involved and whether they have a relationship with clinical outcomes in patients with AML under the age of 65 remain unclear.

Methods

In this study, we developed a multicolor flow cytometry-based assay to monitor the frequency and distribution of γδ T-cell subsets, including central memory γδ T cells (TCM γδ), effector memory γδ T cells (TEM γδ), and TEM expressing CD45RA (TEMRA γδ), in peripheral blood from 30 young (≤65 years old) patients with newly diagnosed non-acute promyelocytic leukemia (also known as M3) AML (AMLy-DN), 14 young patients with AML in complete remission (AMLy-CR), and 30 healthy individuals (HIs).

Results

Compared with HIs, patients with AMLy-DN exhibited a significantly higher differentiation of γδ T cells, which was characterized by decreased TCM γδ cells and increased TEMRA γδ cells. A generally higher TIGIT expression was observed in γδ T cells and relative subsets in patients with AMLy-DN, which was partially recovered in patients with AMLy-CR. Furthermore, 17 paired bone marrow from patients with AMLy-DN contained higher percentages of γδ and TIGIT+ γδ T cells and a lower percentage of TCM γδ T cells. Multivariate logistic regression analyses revealed the association of high percentage of TIGIT+ TCM γδ T cells with an increased risk of poor induction chemotherapy response.

Conclusions

In this study, we investigated the distribution of γδ T cells and their memory subsets in patients with non-M3 AML and suggested TIGIT+ TCM γδ T cells as potential predictive markers of induction chemotherapy response.

Arsenic trioxide: applications, mechanisms of action, toxicity and rescue strategies to date

Arsenical medicine has obtained its status in traditional Chinese medicine for more than 2,000 years. In the 1970s, arsenic trioxide was identified to have high efficacy and potency for the treatment of acute promyelocytic leukemia, which promoted many studies on the therapeutic effects of arsenic trioxide. Currently, arsenic trioxide is widely used to treat acute promyelocytic leukemia and various solid tumors through various mechanisms of action in clinical practice; however, it is accompanied by a series of adverse reactions, especially cardiac toxicity. This review presents a comprehensive overview of arsenic trioxide from preclinical and clinical efficacy, potential mechanisms of action, toxicities, and rescue strategies for toxicities to provide guidance or assistance for the clinical application of arsenic trioxide.

Superiority of anthracycline-free treatment in standard-risk acute promyelocytic leukemia: A systematic review and comparative epidemiological analysis

BACKGROUND

Recent advances in the treatment of acute promyelocytic leukemia (APML) have seen unprecedented improvements in patient outcomes. However, such rapid growth in understanding often leads to uncertainty regarding superiority among candidate treatment regimens, especially when further scrutinized from an epidemiological perspective.

AIMS

The aim of this systematic review with epidemiological analysis was to identify and compare commonly utilized protocols for standard-risk APML with a particular focus on complete remission (CR), overall/disease-free survival (DFS), and reported adverse events.

METHODS AND RESULTS

Medline, Scopus, and CINAHL were interrogated to identify studies utilizing all-trans retinoic acid (ATRA) in addition to arsenic trioxide (ATO) and/or anthracyclines such as idarubicin (IDA) in the treatment of de-novo APML. After collation of studies, an epidemiological analysis was subsequently performed to compare protocols with regards to outcomes of interest using number needed to benefit (NNB) and number needed to harm (NNH) measures. Seventeen articles, describing 12 distinct trials, were included in the analysis. These trials made use of three unique protocols; CR rates were 94%-100% for ATO/ATRA regimens, 95%-96% for ATO/ATRA/anthracycline regimens, and 89%-94% for ATRA/anthracycline regimens. Epidemiological analysis demonstrated NNB for CR was 9.09 (ATO/ATRA vs. ATRA/IDA) and 20.00 (ATO/ATRA vs. ATO/ATRA/IDA), NNH for neutropenia was -3.45 (ATO/ATRA vs. ATRA/IDA), and NNH for infection was -3.13 (ATO/ATRA vs. ATRA/IDA) and -1.89 (ATO/ATRA vs. ATO/ATRA/IDA).

CONCLUSION

The ATO/ATRA regimen is superior to chemotherapy-containing protocols at inducing remission and promoting survival in patients with APML. The regimen is better tolerated than the proposed alternatives with fewer adverse events. Future research opportunities include quantifying APML epidemiology and pursuing oral arsenic as an option for simplification of therapeutic protocols.

Analysis of the clinical characteristics and prognosis of adult de novo acute myeloid leukemia (none APL) with PTPN11 mutations

We discuss the clinical characteristics and prognostic significance of adult individuals with PTPN11 mutations who have developed acute myeloid leukemia (AML) (none acute promyelocytic leukemia). Next generation sequencing and Sanger sequencing were used to detect 51 gene mutations, and multiplex-PCR was used to detect 41 fusion genes from 232 de novo adult AML patients retrospectively. About 7.76% patients harbored PTPN11 mutations, 20 PTPN11 alterations were identified, all of which were missense mutations in the N-SH2 (n = 16) and PTP (n = 4) domains located in exon 3. Patients with PTPN11 mut had significantly higher platelet counts and hemoglobin levels (p < 0.001), which were mainly detected in M5 (n = 12, 66.67%, p < 0.001) subtype. Patients with MLL-AF6 positive showed a higher frequency of PTPN11 mut (p = 0.018) in the 118 AML cases. PTPN11 mut were accompanied by other mutations, which were NPM1 (44.44%), DNMT3A (38.89%), FLT3 (38.89%), and NRAS (17.2%). PTPN11 mut had a negative impact on the complete remission rate in M5 subtype patients (p < 0.001). However, no statistically significant effect on overall survival (OS) with PTPN11 mut patients in the whole cohort and age group (p > 0.05) was observed. Further analysis revealed no significant difference in OS among NPM1 mut/PTPN11 mut, NPM1 mut/PTPN11 wt, DNMT3A mut/PTPN11 mut, and DNMT3A mut/PTPN11 wt patients (p > 0.05). Multivariate analysis showed the proportion of bone marrow blasts ≥65.4% was a factor significantly affecting OS in PTPN11 mut patients (p = 0.043).

Differentiation Syndrome in Acute Leukemia: APL and Beyond

Differentiation syndrome (DS) is a frequent and potentially life-threatening clinical syndrome first recognized with the advent of targeted therapeutics for acute promyelocytic leukemia (APL). DS was subsequently observed more broadly with targeted therapeutics for acute myeloid leukemia (AML). DS is typically characterized by fever, dyspnea, hypotension, weight gain, pleural or pericardial effusions, and acute renal failure. The incidence in patients with APL ranges from 2 to 37%, with the wide variation likely attributed to different diagnostic criteria, use of prophylactic treatment, and different treatment regimens. Treatment with corticosteroids +/- cytoreductive therapy should commence as soon as DS is suspected to reduce DS-related morbidity and mortality. The targeted anti-leukemic therapy should be discontinued in patients with severe DS. Here, we discuss the pathogenesis of DS, clinical presentations, diagnostic criteria, management strategies, and implementation of prospective tracking on clinical trials.

Hematopoietic Stem Cell Transplantation in Acute Promyelocytic Leukemia in the Era of All-Trans Retinoic Acid (ATRA) and Arsenic Trioxide (ATO)

Acute promyelocytic leukemia (APL) currently represents one of the malignant hemopathies with the best therapeutic responses, following the introduction of all-trans retinoic acid (ATRA) and subsequently of arsenic trioxide (ATO) treatment. As a result, a large proportion of patients with APL achieve long-term responses after first-line therapy, so performing a hematopoietic stem cell transplant as consolidation of first complete remission (CR) is no longer necessary. Even in the case of relapses, most patients obtain a new remission as a result of therapy with ATO and ATRA, but an effective consolidation treatment is necessary to maintain it. The experience accumulated from studies published in the last two decades shows the effectiveness of hematopoietic stem cell transplantation (HSCT) in improving the outcome of patients who achieve a new CR. Thus, the expert groups recommend transplantation as consolidation therapy in patients with a second CR, with the indication for autologous HSCT in cases with molecular CR and for allogeneic HSCT in patients with the persistence of minimal residual disease (MRD) or with early relapse. However, there is a variety of controversial aspects related to the role of HSCT in APL, ranging from the fact that outcome data are obtained almost exclusively from retrospective studies and historical analyses to questions related to the type of transplantation, the impact of minimal residual disease, conditioning regimens, or the role of other therapeutic options. All these questions justify the need for controlled prospective studies in the following years.