Acute Promyelocytic Leukemia: Update on Risk Stratification and Treatment Practices

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.

Clinical characteristics of a patient with de novo acute promyelocytic leukemia with JAK2 v617f mutation

BACKGROUND

The V617F mutation of Janus-associated kinase 2 (JAK2) is common in myeloproliferative neoplasms (MPN). JAK2 V617F mutation can be detected in patients with de novo acute myeloid leukemia (AML), but de novo acute promyelocytic leukemia (APL) with JAK2 V617F mutation is rare.

CASE PRESENTATION

We report a case of APL with both the t(15;17) translocation as well as the JAK2 V617F mutation that transformed into MPN (PV/ET).

CONCLUSIONS

A de novo APL patient presented initially with JAK2 V617F. After ATRA and ATO dual induction and chemotherapy consolidation, the patient achieved complete remission (CR) with undetectable PML/RARα. However, the JAK2 V617F remained positive, and the patient developed MPN (PV/ET) 22 months later, which responded well to interferon therapy.AML, acute myeloid leukemia; APL, acute promyelocytic leukemia; ATRA, all-trans retinoic acid; ATO, arsenic trioxide; BM, bone marrow; CR, complete remission; ET, essential thrombocythemia; Hb, hemoglobin; JAK2, Janus-associated kinase 2; MPN, myeloproliferative neoplasms; PLT, platelets; PMF, primary myelofibrosis; PML/RARα; PV, polycythemia vera; WBC, white blood cells.