Differentiation Syndrome in Acute Leukemia: APL and Beyond

How I treat acute myeloid leukemia with differentiation therapy

ABSTRACT

An increasing number of acute myeloid leukemia (AML) therapeutics have been developed, not as cytotoxic therapies but rather as targeted agents able to restore the aberrant and leukemogenic "block" in normal differentiation. All-trans retinoic acid and arsenic trioxide are classic examples of differentiating agents for treatment of acute promyelocytic leukemia (APL); newer therapies functioning through differentiation include isocitrate dehydrogenase 1 and 2 inhibitors, FMS-like tyrosine kinase 3 inhibitors, and menin inhibitors. The terminal differentiation of leukemic blasts via differentiating-agent therapy can lead to a constellation of signs and symptoms, originally referred to as "retinoic acid syndrome" and now termed "differentiation syndrome" (DS), characterized predominantly by systemic inflammatory response system-like features of dyspnea, pulmonary infiltrates, pleural and pericardial effusions, unexplained fevers, hypotension, edema, and renal insufficiency. DS in patients with newly diagnosed APL is generally straightforward to identify; however, DS in patients with multiply relapsed AML can be more challenging to diagnose, due to nonspecific signs and symptoms that can be mistakenly attributed to infectious etiologies or the underlying refractory leukemia itself. Prompt consideration of DS, rapid initiation of systemic corticosteroids, and early cytoreduction in the setting of concomitant hyperleukocytosis are essential for optimal management.

Pulmonary Complications in Hematologic Malignancies

Patients with hematologic malignancies are at risk for infectious and noninfectious pulmonary complications. An integrated diagnostic approach tailored to the patient's malignancy and treatment history and clinical presentation should be initiated with close interdisciplinary collaboration among specialists.

The clinical characteristics and implications of acute kidney injury during induction therapy for acute promyelocytic leukemia

Background

Dual induction with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has made acute promyelocytic leukemia (APL) a curable disease. However, differentiation syndrome (DS) can be a life-threatening complication of induction therapy. It is considered to result from a severe systemic inflammatory response mediated by increased expression of cytokines, chemokines, and adhesion molecules on differentiating blast cells. The kidney, as a vital organ rich in the capillary endothelium, could be targeted by differentiating blasts in DS. Acute kidney injury (AKI) is a rare but severe consequence of DS secondary to ATRA and ATO induction and can result in renal failure and early mortality. Nevertheless, its clinical characteristics and impact on APL prognosis have yet to be elucidated.

Objectives

The aim of this study was to describe the clinical characteristics of DS-related AKI in patients with APL and its impact on patient prognosis.

Methods

This was a retrospective study from a single center in a real-world setting. APL patients who developed AKI during ATRA- and ATO-based induction were included. The patients' clinical/laboratory data and outcome information were retrieved from the electronic medical records.

Results

From January 2011 to March 2024, a total of 26 out of 572 (4.5%) APL patients were identified as having AKI during dual induction. Among them, eight patients received continuous renal replacement therapy, and 3/8 patients experienced early death (ED), which was defined as death within 3 months of diagnosis. Among the five non-ED patients, three did not recover from renal function and were still dialysis-dependent during the follow-up. The estimated 2-year overall survival rate for all patients was 42%, and the ED rate was 30.8%. Survival analysis revealed that a greater tumor burden, a rapidly increasing WBC count, worse coagulation parameters, and persistent renal dysfunction were associated with a more adverse prognosis.

Conclusion

AKI is a rare but severe complication of DS in the ATRA + ATO dual-induction era of APL. It is associated with a high ED rate and dismal long-term survival. Some patients develop irreversible renal dysfunction and become dialysis-dependent after leukemia remission. Thus, the management of AKI in APL patients is still a clinical challenge, and a deeper understanding of its pathogenesis, along with multidisciplinary efforts, is needed.

Revumenib for patients with acute leukemia: a new tool for differentiation therapy

Treatment of acute leukemia is gradually moving away from a "one-size-fits-all" approach, as scientific and clinical advances expand the arsenal of available targeted therapies. One of the recent additions is the group of menin inhibitors; oral, selective, small molecules that disrupt the interaction between the chromatin adapter menin, and an epigenetic regulator, the lysine methyltransferase 2A (KMT2A) complex. Two susceptible leukemia subtypes have been identified: (i) acute myeloid leukemia with a mutation in nucleophosmin 1 (NPM1), and (ii) any acute leukemia, myeloid or lymphoid, with a translocation resulting in the rearrangement of KMT2A. These leukemias share a distinct genetic expression, maintained by the KMT2A-menin interaction. Together they account for approximately 40% of patients with acute myeloid leukemia and 10% of patients with acute lymphoblastic leukemia. This spotlight review follows the journey of revumenib, as a representative of menin inhibitors, from bench to bedside. It focuses on the pathophysiology of leukemias sensitive to menin inhibition, delineation of how this understanding led to targeted drug development, and data from clinical trials. The important discovery of resistance mechanisms is also explored, as well as future directions in the use of menin inhibitors for treating leukemia.

MRD in Acute Leukemias: Lessons Learned from Acute Promyelocytic Leukemia

Introduction: Advances in molecular biology, polymerase chain reaction (PCR), and next-generation sequencing (NGS) have transformed the concept of minimal residual disease (MRD) from a philosophical idea into a measurable reality. Current Treatment Paradigms and Lessons Learned from APL: Acute promyelocytic leukemia (APL) leads the way in this transformation, initially using PCR to detect MRD in patients in remission, and more recently, aiming to eliminate it entirely with modern treatment strategies. Along the way, we have gained valuable insights that, when applied to other forms of acute leukemia, hold the potential to significantly improve the outcomes of these challenging diseases. Does the BM Microenvironment Play a Role in MRD?: In this review, we explore the current use of MRD in the management of acute leukemia and delve into the biological processes that contribute to MRD persistence, including its overlap with leukemia stem cells and the role of the bone marrow microenvironment.

ATPR induces acute promyelocytic leukemia cells differentiation and cycle arrest via the lncRNA CONCR/DDX11/PML-RARα signaling axis

Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia (AML) with a high mortality rate, and the production of PML-RARα fusion protein is the cause of its pathogenesis. Our group has synthesized a novel compound, 4-amino-2-trifluoromethyl-phenyl retinate (ATPR), by structural modification of All-trans retinoic acid (ATRA), which has strong cell differentiation-inducing effects and inhibits the expression of PML-RARα. In this study, acute promyelocytic leukemia NB4 cells before and after ATPR induction were analyzed by whole transcriptome microarray, and the expression of lncRNA CONCR was found to be significantly downregulated. The role of CONCR in ATPR-induced cell differentiation and cycle arrest was explored through overexpression and silencing of CONCR. And then the database was used to predict that CONCR may bind to DEAD/H-Box Helicase 11 (DDX11) protein to further explore the role of CONCR binding to DDX11. The results showed that ATPR could reduce the expression of CONCR, and overexpression of CONCR could reverse the ATPR-induced cell differentiation and cycle blocking effect, and conversely silencing of CONCR could promote this effect. RNA immunoprecipitation (RIP) experiments showed that CONCR could bind to DDX11, the protein expression levels of DDX11 and PML-RARα were elevated after overexpression of CONCR. These results suggest that ATPR can regulate the expression of DDX11 through CONCR to affect the expression of PML-RARα fusion protein, which in turn induces the differentiation and maturation of APL cells.