The aim of this study was to determine the efficacy and safety of treatment of pediatric acute promyelocytic leukemia (APL) with single-agent arsenic trioxide (ATO). A total of 19 children (< 15 years of age) with newly diagnosed APL were treated with single-agent ATO for remission induction and postremission therapy. Seventeen of the children (89.5%) achieved complete hematologic remission, and 2 early deaths occurred from intracranial hemorrhage. ATO-induced leukocytosis was observed in 13 (68.4%) patients. Other ATO-related toxicities were minimal and transient. Postremission ATO therapy continued for 3 years; the most common side effect was ATO-induced neutropenia. With a median follow-up of 53 months (range, 23-76 months), the calculated 5-year overall survival and eventfree survival were 83.9% and 72.7%, respectively, which are comparable with results achieved by the use of ATRA plus chemotherapy, which is the standard therapy for APL. No chronic arsenic toxicity or second malignancies were found during the follow-up period, and arsenic retention was not significant in patients off treatment more than 24 months. IntroductionAcute promyelocytic leukemia (APL) accounts for approximately 10% of childhood acute myeloid leukemia. [1][2][3][4] APL is characterized by the French-American-British M3 subtype morphology, a distinctive immunophenotype, and, in the majority of cases, there is a t(15;17) chromosomal translocation that generates the promyelocytic leukemia-retinoic acid receptor-␣ (PML-RARa) fusion gene. This specific genetic lesion determines the unique response to treatment with all-trans retinoic acid (ATRA) or arsenic trioxide (ATO). 5 Since the introduction of ATRA in the 1980s and ATO in the 1990s, the strategy for treating APL has shifted from conventional chemotherapy to cancer cell differentiation and cancer-targeted therapy. The combination of ATRA and anthracycline-based chemotherapy is currently the standard approach to treat newly diagnosed APL. With this regimen, the hematologic complete remission (HCR) rate has improved significantly, to more than 90%; 5-year disease-free survival is more than 70%. 5-10 However, some problems still remain; notably, ATRA-related side effects appear to be more pronounced in children than in adult patients, 4,11-13 the optimal postremission therapy still remains to be defined, and approximately 20% to 30% of patients eventually relapse and develop drug resistance.ATO has proven to be another highly effective agent in APL therapy. 14-21 ATO differs from ATRA because of its dual effects of inducing partial differentiation and apoptosis of APL cells. Although highly efficacious, ATO is most commonly used in refractory or relapsed APL for inducing remission. It has previously been shown that single-agent ATO is equally effective in inducing remission in newly diagnosed cases of adult APL. However, little is known about the use of single-agent ATO in the treatment of children with APL. The optimal dosage and route of administration during remission induction and ...

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BACKGROUND:The prognosis of acute promyelocytic leukemia (APL) in the elderly is poorer than that of younger patients after treatment with all-trans retinoic acid plus chemotherapy, which is the current standard therapy for APL. A significantly higher mortality during consolidation therapy was found, which is mainly due to deaths from sepsis following chemotherapy-induced myelosuppression. METHODS: A total of 33 patients aged 60 years or older with de novo APL were treated with single-agent arsenic trioxide (ATO) for remission induction and postremission therapy. The postremission therapy continued for up to 4 years. RESULTS: Twentynine patients (87.9%) achieved a hematologic complete remission, and the most common adverse event during remission induction was leukocytosis (63.6%). Definite differentiation syndrome was observed in 5 patients. Nonhematologic adverse events were all manageable and reversible. Twenty-eight patients proceeded to postremission therapy. Adverse effects during postremission therapy were mild, transient, and no treatment was required. No patients died from ATO-related toxicities. With a median follow-up of 99 months, the 10-year cumulative incidence of relapse, overall survival, disease-free survival, and cause-specific survival were 10.3%, 69.3%, 64.8%, and 84.8%, respectively, which are comparable with those in the younger APL partners. No significant risks for development of chronic arsenicosis or second malignancy were observed during the follow-up period. CONCLUSIONS: The results indicate that the single-agent ATO regimen is safe and effective with long-term durable remission, and could be used as first-line treatment

Inactivation of Dickkopf-3 (DKK3) is closely associated with a poor prognosis in various solid tumor and hematologic malignancies. Promoter hypermethylation is one potential cause of DKK3 inactivation. However, whether other mechanisms lead to DKK3 inactivation and the subsequent effects of these inactivations on cell proliferation and the Wnt signaling pathway in adult B acute lymphoblastic leukemia (B-ALL) remain unclear. In the present study, we found that low DKK3 expression levels were associated with high miR-708 expression and promoter hypermethylation in adult B-ALL. miR-708 was confirmed to directly decrease DKK3 expression in Nalm-6 and BALL-1 cells. Additionally, a miR-708 inhibitor decreased cell proliferation mainly through apoptosis and cell cycle arrest at the G1 phase, and these effects were eliminated by DKK3 siRNA treatment. Moreover, the demethylating agent 5-aza-2′-deoxycytidine (5-aza) decreased the methylation state of the DKK3 promoter based on methylation-specific PCR (MSP) and bisulfite genomic sequencing PCR (BSP), although this demethylation effect was not enhanced by the miR-708 inhibitor. The miR-708 inhibitor or 5-aza significantly increased DKK3 expression and decreased p-GSK3β, cyclin D1 and nuclear and cytoplasmic β-catenin protein expression, indicating that the Wnt/β-catenin signaling pathway was inhibited. These effects became more pronounced when the miR-708 inhibitor and 5-aza were used simultaneously. These findings provide greater insights into the mechanisms that increase DKK3 expression and suggest that a miR-708 inhibitor and 5-aza might be useful as targeted therapies for adult B-ALL.

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