The hallmark of acute promyelocytic leukemia (APL) is the presence of the characteristic fusion transcript of the promyelocytic leukemia gene with the retinoic acid receptor α gene (PML::RARA). The PML::RARA fusion is a molecular target for all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). Therapies based on ATRA plus ATO have excellent outcomes in terms of complete remission rates, overall survival, and achievement of deep and durable molecular responses with a very low incidence of relapse. However, although the combination of ATRA and ATO has lower hematologic toxicity than standard chemotherapy, its use is associated with a spectrum of distinctive toxicities, such as differentiation syndrome, liver toxicity, QT interval prolongation, and neurotoxicity. Rigorous monitoring of patients’ clinical evolution is indispensable for identifying and addressing each complication. The objective is to maintain an equilibrium between treatment-induced adverse events and therapeutic efficacy. This paper focused on non-hematologic complications associated with the combination of ATRA and ATO. Additionally, we discuss late-onset complications of this therapy. In summary, the majority of treatment-related adverse events are manageable, self-limiting, and reversible. More so, there seems to be a lower incidence rate of secondary neoplasms compared to standard chemotherapy. However, further research is required to assess how the ATRA plus ATO regimen affects the emergence of additional comorbidities.

FMS-like tyrosine kinase 3 (FLT3) is a crucial regulator of normal hematopoiesis, with high expression in hematopoietic stem and progenitor cells. Beyond its role in stem cell survival and proliferation, FLT3 signaling is essential for immune regulation, particularly dendritic cell differentiation and NK cell expansion. In acute myeloid leukemia (AML), FLT3 mutations—most commonly internal tandem duplications (FLT3-ITD) and tyrosine kinase domain (FLT3-TKD) substitutions—are among the most frequent genetic alterations, driving constitutive activation of proliferative and antiapoptotic pathways and conferring adverse prognosis. The clinical development of FLT3 inhibitors has been a decades-long endeavor. Early multikinase agents established proof-of-concept but were hampered by off-target effects and incomplete efficacy. The subsequent generation of potent and selective inhibitors has transformed outcomes, culminating in FDA approvals of midostaurin, quizartinib, and gilteritinib. Together with allogeneic transplantation, these agents have reshaped the treatment paradigm for FLT3-mutant AML, converting a historically high-risk subset into one with realistic prospects for long-term survival. Despite these advances, challenges remain. Resistance emerges through cell-intrinsic mechanisms such as acquisition of secondary TKD or RAS pathway mutations, metabolic reprogramming, and antiapoptotic shifts, as well as cell-extrinsic mechanisms mediated by the bone marrow microenvironment, including cytokine support, stromal CYP3A4 metabolism, and retinoid inactivation. These pathways sustain measurable residual disease (MRD), the key predictor of relapse. Rational combination strategies and MRD-directed approaches are therefore essential to fully realize the curative potential of FLT3 inhibition.

Acute promyelocytic leukemia (APL) is generated by the PML-RARA fusion gene. In patients suffering from APL, the early diagnosis and treatment are essential in the successful management. We reported a case of a 27-year-old 17th-week pregnant patient diagnosed with APL. After an extensive hematological diagnostic panel, the acute promyelocytic leukemia was confirmed, and the patient received all-trans retinoic acid (ATRA), idarubicin (IDA), and dexamethasone, following national guidelines. Due to ATRA-related differentiation syndrome, the therapy was adjusted, and hydroxycarbamide was added with a good outcome. The patient was admitted to the ICU secondary to hypoxemic respiratory failure on the 2nd day after hospital admission. Our patient received an individualized drug combination, adjusted by the clinical response. Furthermore, the drugs used in APL treatment are all teratogenic. Despite various major complications, including severe acute respiratory distress syndrome (ARDS), which needed mechanical ventilation; ICU-acquired myopathy; and spontaneous abortion, the patient had a good outcome and was transferred from the ICU after a total stay of 40 days. APL during pregnancy is a rare entity of intermediate-risk APL. Our study emphasized the need for individualized therapy in a rare case of a pregnant woman diagnosed with a potentially fatal hematologic disease.

The hallmark of acute promyelocytic leukemia (APL) is the presence of the characteristic fusion transcript of the promyelocytic leukemia gene with the retinoic acid receptor α gene (PML::RARA), which is a molecular target for all-transretinoic acid (ATRA) and arsenic trioxide (ATO). Therapies with ATRA plus ATO have excellent outcomes in terms of complete remission rate, overall survival, and achievement of a deep and durable molecular response with a very low incidence of relapse. However, although the combination of ATRA and ATO has lower hematologic toxicity than standard chemotherapy, its use is associated with a spectrum of unique toxicities, such as hepatic toxicity, QTc (QT interval corrected) prolongation, neurotoxicity, and differentiation syndrome. Hematologists treating patients with acute promyelocytic leukemia should be aware of possible early-complications of the ATRA plus ATO regimen and aim to balance treatment-related adverse events and efficacy. Careful follow-up of the patient’s clinical course is essential to identify and treat each complication. This study focused on treatment-related complications during induction and consolidations in patients with APL who received ATRA plus ATO. We retrospectively analyzed 26 adult patients diagnosed with APL between 2019 and 2022 at our center to identify the incidence rate, severity and time of onset of short-term non-hematologic adverse events relative to the initiation of the ATRA and ATO regimen. Additionally, we review the existing literature regarding the toxic side effects of ATO in APL and discuss how its most frequent toxicities should be managed. The median follow-up of our patients was 21.5 months (range, 1-48 months) and the most common adverse events were hepatic toxicity (69.2%), infections (46.1%), differentiation syndrome(23%) and QT prolongation (11.5%). All patients experienced at least one adverse event and grade 3 and 4 toxicities occurred in 57.6 % patients; these generally consisted of liver enzyme elevations, QTc prolongation, but also some rare manifestations such as musculoskeletal pain syndrome (1 patient) and ATO-related pancreatitis (1 patient). Most patients developed side-effects during induction. This is the first study about Romanian patients diagnosed with APL. Our results suggest that all treatment-related adverse events, except for differentiation syndrome are manageable, self-limiting and reversible. All patients, except for two (one died during induction and one died during consolidation), were able to complete the treatment consolidation with ATO and ATRA.