Management of relapsed and refractory childhood acute promyelocytic leukaemia: recommendations from an international expert panel

Pediatric Autologous Hematopoietic Stem Cell Transplantation: Safety, Efficacy, and Patient Outcomes. Literature Review

Autologous stem cell transplantation (auto-HSCT) is a part of the therapeutic strategy for various oncohematological diseases. The auto-HSCT procedure enables hematological recovery after high-dose chemotherapy, otherwise not tolerable, by the infusion of autologous hematopoietic stem cells. Unlike allogeneic transplant (allo-HSCT), auto-HSCT has the advantage of lacking acute-graft-versus-host disease (GVHD) and prolonged immunosuppression, however, these advantages are counterbalanced by the absence of graft-versus-leukemia. Moreover, in hematological malignancies, the autologous hematopoietic stem cell source may be contaminated by neoplastic cells, leading to disease reappearance. In recent years, allogeneic transplant-related mortality (TRM) has progressively decreased, almost approaching auto-TRM, and many alternative donor sources are available for the majority of patients eligible for transplant procedures. In adults, the role of auto-HSCT compared to conventional chemotherapy (CT) in hematological malignancies has been well defined in many extended randomized trials; however, such trials are lacking in pediatric cohorts. Therefore, the role of auto-HSCT in pediatric oncohematology is limited, in both first- and second-line therapies and still remains to be defined. Nowadays, the accurate stratification in risk groups, according to the biological characteristics of the tumors and therapy response, and the introduction of new biological therapies, have to be taken into account in order to assign auto-HSCT a precise role in the therapeutic strategies, also considering that in the developmental age, auto-HSCT has a clear advantage over allo-HSCT, in terms of late sequelae, such as organ damage and second neoplasms. The purpose of this review is to report the results obtained with auto-HSCT in the different pediatric oncohematological diseases, focusing on the most significant literature data in the context of the various diseases and discussing this data in the light of the current therapeutic landscape.

Gemtuzumab Ozogamicin Followed by Unrelated Cord Blood Transplantation With Reduced-intensity Conditioning for a Child With Refractory Acute Promyelocytic Leukemia

There is no established treatment for patients with acute promyelocytic leukemia (APL) refractory to targeted therapies with all-trans retinoic acid (ATRA) and/or arsenic trioxide (ATO). We report here a case of an 8-month-old girl with APL who failed standard ATRA-combined chemotherapy. Although molecular remission was achieved after introducing ATRA/ATO combination therapy, molecular relapse occurred during the ATO consolidation courses. Subsequent molecular remission was rapidly achieved after administering 2 doses of gemtuzumab ozogamicin. She was successfully treated with unrelated cord blood transplantation using reduced-intensity conditioning. Gemtuzumab ozogamicin might be a preferable choice for patients with APL refractory to standard therapy.

Evaluation of reporting quality in clinical practice guidelines for acute myeloid leukemia using the RIGHT checklist

BACKGROUND

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy. Clinical practice guidelines (CPGs) on the management of AML have great value in clinical practice. However, the reporting quality of CPGs for AML has not yet been evaluated. This is the first study aiming to evaluate the reporting quality of the most recent AML CPGs published worldwide using the Reporting Items for Practice Guidelines in Healthcare (RIGHT) checklist.

METHODS

We systematically searched PubMed, Chinese National Knowledge Infrastructure (CNKI), Wanfang, and Chinese Biomedical Literature (CBM) to extract CPGs for AML published between January 2016 and December 2020. Websites for guideline development organizations and medical associations were also searched. Two independent researchers assessed compliance of the guidelines to each of the 35 checklist items and summarized reporting rates for the 7 domains of the RIGHT checklist.

RESULTS

We identified 16 guidelines, of which 3 (18.8%) were written in Chinese and 13 (81.3%) were written in English. The average overall reporting rate of the 16 guidelines was 52.9%, and only 7 CPGs (43.8%) had a reporting rate >50%. The average reporting rates of the 7 domains (basic information; background; evidence; recommendations; review and quality assurance; funding, declaration, and management of interests; and other information) were 79.2%, 62.5%, 38.8%, 53.6%, 21.9%, 32.8%, and 43.8%, respectively. For the 35 checklist items, the average reporting rate was 52.9%, and only 16 items had a reporting rate >50%, of which 5 items were reported by all the guidelines. There was 1 item which was not reported by any of the guidelines.

CONCLUSIONS

The reporting quality of recently published AML guidelines remains poor. While the recommendations of CPGs have great value in clinical practice, the reporting quality of CPGs for AML still needs to be improved.

Population Pharmacokinetics and Safety of Oral Tetra-Arsenic Tetra-Sulfide Formula in Pediatric Acute Promyelocytic Leukemia

Background

An oral tetra-arsenic tetra-sulfide (AS₄S₄) formula has been recommended as an outpatient post-remission treatment for Chinese adults with acute promyelocytic leukemia (APL) but limited data are available for children. In this exploratory study, we aimed to evaluate the pharmacokinetics and safety of the AS₄S₄ formula in children.

Methods

Eleven newly diagnosed and one relapsed pediatric patient (4–14 years of age) treated with the AS₄S₄ formula were included. Blood samples were collected from 12 children, and drug concentrations were quantified by ICP-MS. Population pharmacokinetic analysis and Monte-Carlo simulation were performed using NONMEM software. Toxic effects were graded according to the NCI-CTCAE, Version 3.

Results

A total of 107 arsenic concentrations (0.1–75.0 µg L⁻¹) were used for population pharmacokinetic analysis. The median (range) of estimated weight-normalized CL and volume distribution at steady-state were 45.26 (35.63–82.18) L h⁻¹ kg⁻¹ and 230.37 (85.96–495.68) L kg⁻¹, respectively. No patients discontinued AS₄S₄ treatment owing to adverse events, and there were no drug-related adverse events over grades 3–4. All newly diagnosed APL patients were in MCR with a median follow-up of 28 months (range, 23 to 37 months). Both the estimated 3-year EFS and OS rates were 100%.

Conclusion

The pharmacokinetics and safety oral AS₄S₄ formula was evaluated for the first time in pediatric APL. The pharmacokinetic assessment demonstrated that the dosing regimen of 60 mg/kg/d TID resulted in a higher steady-state through concentration in children than that which was achieved in adults. The results of this study indicate that the AS₄S₄ formula is safe in newly diagnosed pediatric APL patients.

Acute Promyelocytic Leukemia in Children: A Model of Precision Medicine and Chemotherapy-Free Therapy

Acute promyelocytic leukemia (APL) represents a paradigm of precision medicine. Indeed, in the last decades, the introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) completely revolutionized the therapeutic approach to this previously highly fatal disorder. This entirely chemotherapy-free treatment, which provided excellent survival rates, has been initially validated in adults and, recently, translated in the pediatric setting. This review summarizes currently available data on the use of ATRA and ATO combination in pediatric APL, providing a particular focus on peculiar issues and challenges, such as the occurrence of pseudotumor cerebri and death during induction (early death), as well as the advantage offered by the ATO/ATRA combination in sparing long-term sequelae.

Management of relapse in acute promyelocytic leukaemia treated with up-front arsenic trioxide-based regimens

The standard of care for patients with acute promyelocytic leukaemia (APL) relapsing after front-line treatment with arsenic trioxide (ATO)-based regimens remains to be defined. A total of 67 patients who relapsed after receiving ATO-based up-front therapy and were also salvaged using an ATO-based regimen were evaluated. The median (range) age of patients was 28 (4-54) years. While 63/67 (94%) achieved a second molecular remission (MR) after salvage therapy, three (4·5%) died during salvage therapy. An autologous stem cell transplant (auto-SCT) was offered to all patients who achieved MR, 35/63 (55·6%) opted for auto-SCT the rest were administered an ATO + all-trans retinoic acid maintenance regimen. The mean (SD) 5-year Kaplan-Meier estimate of overall survival and event-free survival of those who received auto-SCT versus those who did not was 90·3 (5·3)% versus 58·6 (10·4)% (P = 0·004), and 87·1 (6·0)% versus 47·7 (10·3)% (P = 0·001) respectively. On multivariate analysis, failure to consolidate MR with an auto-SCT was associated with a significantly increased risk of relapse [hazard ratio (HR) 4·91, 95% confidence interval (CI) 1·56-15·41; P = 0·006]. MR induction with ATO-based regimens followed by an auto-SCT in children and young adults with relapsed APL who were treated with front-line ATO-based regimens was associated with excellent long-term survival.

Targeted Therapies for Pediatric AML: Gaps and Perspective

Acute myeloid leukemia (AML) is a hematopoietic disorder characterized by numerous cytogenetic and molecular aberrations that accounts for ~25% of childhood leukemia diagnoses. The outcome of children with AML has increased remarkably over the past 30 years, with current survival rates up to 70%, mainly due to intensification of standard chemotherapy and improvements in risk classification, supportive care, and minimal residual disease monitoring. However, childhood AML prognosis remains unfavorable and relapse rates are still around 30%. Therefore, novel therapeutic approaches are needed to increase the cure rate. In AML, the presence of gene mutations and rearrangements prompted the identification of effective targeted molecular strategies, including kinase inhibitors, cell pathway inhibitors, and epigenetic modulators. This review will discuss several new drugs that recently received US Food and Drug Administration approval for AML treatment and promising strategies to treat childhood AML, including FLT3 inhibitors, epigenetic modulators, and Hedgehog pathway inhibitors.