Arsenic trioxide and low-dose cytarabine for patients with intermediate-2 and high-risk myelodysplastic syndrome

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.

Representation of therapy-related myelodysplastic syndrome in clinical trials over the past 20 years

Therapy-related myelodysplastic syndrome (t-MDS), defined as MDS occurring after previous exposure to chemotherapy or radiotherapy, constitutes 10% to 20% of all MDS diagnoses. t-MDS patients tend to have higher-risk disease and worse outcomes than de novo MDS patients and are often excluded from therapeutic clinical trials. To explore this further, we extracted clinical trials across all status types registered on ClinicalTrials.gov from 1999 to 2018 studying untreated MDS patients. Using these specific search criteria, we analyzed 317 therapeutic MDS trials based on study status, therapeutic indication, eligibility criteria, and sponsor type to examine if these factors influenced t-MDS patient inclusion. Only 18 studies (5.7%) accrued 231 t-MDS patients in total, representing 3.2% of the total accrued MDS trial patient population. Fewer t-MDS patients were accrued in therapeutic trials sponsored by pharmaceutical sponsors vs nonpharmaceutical sponsors (2.8% vs 4.0%; P = .0073). This pattern of exclusion continues in actively enrolling trials; only 5 (10%) of 49 studies specifically mention the inclusion of t-MDS patients in their eligibility criteria. Our results indicate that therapeutic MDS trials seem to exclude t-MDS patients, rendering study results less applicable to this subset of MDS patients, who often have poor outcomes. Our study emphasizes the importance of the recent focus by National Cancer Institute cooperative groups and societies to broaden eligibility criteria for all patients.

Curcumin reduces the expression of survivin, leading to enhancement of arsenic trioxide-induced apoptosis in myelodysplastic syndrome and leukemia stem-like cells

Low response, treatment-related complications and relapse due to the low sensitivity of myelodysplastic syndrome (MDS) and leukemia stem cells (LSCs) or pre-LSCs to arsenic trioxide (ATO), represent the main problems following treatment with ATO alone in patients with MDS. To solve these problems, a chemosensitization agent can be applied to increase the susceptibility of these cells to ATO. Curcumin (CUR), which possesses a wide range of anticancer activities, is a commonly used chemosensitization agent for various types of tumors, including hematopoietic malignancies. In the present study, we investigated the cytotoxic effects and potential mechanisms in MDS-SKM-1 and leukemia stem-like KG1a cells treated with CUR and ATO alone or in combination. CUR and ATO exhibited growth inhibition detected by MTT assays and apoptosis analyzed by Annexin V/PI analyses in both SKM-1 and KG1a cells. Apoptosis of SKM-1 and KG1a cells determined by Annexin V/PI was significantly enhanced in the combination groups compared with the groups treated with either agent alone. Further evaluation was performed by western blotting for two hallmark markers of apoptosis, caspase-3 and cleaved-PARP. Co-treatment of the cells with CUR and ATO resulted in significant synergistic effects. In SKM-1 and KG1a cells, 31 and 13 proteins analyzed by protein array assays were modulated, respectively. Notably, survivin protein expression levels were downregulated in both cell lines treated with CUR alone and in combination with ATO, particularly in the latter case. Susceptibility to apoptosis was significantly increased in SKM-1 and KG1a cells treated with siRNA-survivin and ATO. These results suggested that CUR increased the sensitivity of SKM-1 and KG1a cells to ATO by downregulating the expression of survivin.

The evolution of arsenic in the treatment of acute promyelocytic leukemia and other myeloid neoplasms: Moving toward an effective oral, outpatient therapy

The therapeutic potential of arsenic derivatives has long been recognized and was recently rediscovered in modern literature. Early studies demonstrated impressive activity of this compound in patients with relapsed acute promyelocytic leukemia (APL). Over the last 2 decades, intravenous arsenic trioxide has been used successfully, both alone and in combination with other agents, for the treatment of APL and, with some success, of other myeloid neoplasms. Arsenic trioxide is currently part the standard of care for patients with APL. More recently, oral formulations of this compound have been developed and are entering clinical practice. In this review, the authors discuss the evolution of arsenic in the treatment of APL and other myeloid neoplasms.

A phase II study of arsenic trioxide in patients with relapsed or refractory malignant lymphoma

Limited data have been reported regarding the use of arsenic trioxide (ATO) in the treatment of patients with relapsed or refractory malignant lymphoma; therefore, the present phase II study evaluated the efficacy and toxicity of ATO in such patients. A total of 35 patients were treated with ATO (0.25 mg/kg) infused for 1 h daily, 5 days a week, for a 6-week cycle. Patients were evaluated for the efficacy and toxicity of this regimen. The primary outcome evaluated was the overall response rate (ORR), including the complete and partial response rates. The secondary outcomes evaluated were the overall survival (OS), progression-free survival (PFS), and toxicity. Tumor response data were obtained from all 35 enrolled patients. The ORR was 43%, including complete responses in four patients (11%) and partial responses in 11 patients (31%). The median duration of response was 16 weeks (range 11-23 weeks). The median OS was 79 weeks (range 14-171 weeks), and the median PFS was 55 weeks (range 14-135 weeks). Grade I or II hematological toxicities were the most commonly reported adverse events. The results of this study appear promising for the treatment of relapsed or refractory malignant lymphoma, with well-tolerated ATO toxicity.

Prevalence, management, and clinical consequences of QT interval prolongation during treatment with arsenic trioxide

PURPOSE

Arsenic trioxide (ATO) is a highly effective agent for the treatment of acute promyelocytic leukemia (APL). QT interval prolongation is common with ATO and can pose a barrier to effective administration. The objective of this study was to characterize the prevalence, management, and clinical consequences of QT prolongation in a large cohort of patients treated with ATO.

PATIENTS AND METHODS

We analyzed 3,011 electrocardiograms from 113 patients with non-APL acute myeloid leukemia and myelodysplastic syndrome who were treated on a previously reported clinical trial. QT intervals were assessed using four different correction formulas, and data were correlated with clinical parameters and treatment with ATO.

RESULTS

There were no clinically significant cardiac events in the study population. Of those receiving ATO therapy, 29 patients (26%) had rate-uncorrected QT values above 470 ms and 13 (12%) had values exceeding 500 ms. With the commonly used Bazett rate correction formula, 102 patients (90%) had QTc greater than 470 ms, including 74 (65%) above 500 ms. By using alternative rate correction formulas, only 24% to 32% of patients had rate-corrected QT intervals above 500 ms.

CONCLUSION

QT interval prolongation is common with ATO treatment, but clinically significant arrhythmias are rare and can be avoided with appropriate precautions. Use of the Bazett correction may result in unnecessary interruptions in ATO therapy, and alternative rate correction formulas should be considered for routine electrocardiographic monitoring.

The Challenge of AML in Older Patients

There has been a gradual improvement in the outcome for younger patients with Acute Myeloid Leukaemia over the last two decades, but unfortunately this same progress is not apparent in older patients. “Old” has come to mean rather arbitrarily, patients over 60 years. This age cut off has been perpetuated by clinical trials whose eligibility is frequently at this cut point. Age is a continuous variable right through all age groups with AML and has independent prognostic significance. Chemo-resistance of the disease itself is part of the explanation, with a high frequency of adverse biology occurring at older age. Patient characteristics which compromise the delivery of treatment of adequate intensity are the other important influence. Medical co-morbidities are more frequent, and when combined with what is sometimes referred to as limited haematopoietic reserve, undoubtedly make successful delivery of intensive therapy less likely. The outstanding problem for older patients is that remission is usually not durable, and there has been little improvement in overall survival for the last three decades, then new approaches need.