Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

Upfront dexrazoxane for the reduction of anthracycline-induced cardiotoxicity in adults with preexisting cardiomyopathy and cancer: a consecutive case series

BACKGROUND

Cardiotoxicity associated with anthracycline-based chemotherapies has limited their use in patients with preexisting cardiomyopathy or heart failure. Dexrazoxane protects against the cardiotoxic effects of anthracyclines, but in the USA and some European countries, its use had been restricted to adults with advanced breast cancer receiving a cumulative doxorubicin (an anthracycline) dose > 300 mg/m2. We evaluated the off-label use of dexrazoxane as a cardioprotectant in adult patients with preexisting cardiomyopathy, undergoing anthracycline chemotherapy.

METHODS

Between July 2015 and June 2017, five consecutive patients, with preexisting, asymptomatic, systolic left ventricular (LV) dysfunction who required anthracycline-based chemotherapy, were concomitantly treated with off-label dexrazoxane, administered 30 min before each anthracycline dose, regardless of cancer type or stage. Demographic, cardiovascular, and cancer-related outcomes were compared to those of three consecutive patients with asymptomatic cardiomyopathy treated earlier at the same hospital without dexrazoxane.

RESULTS

Mean age of the five dexrazoxane-treated patients and three patients treated without dexrazoxane was 70.6 and 72.6 years, respectively. All five dexrazoxane-treated patients successfully completed their planned chemotherapy (doxorubicin, 280 to 300 mg/m2). With dexrazoxane therapy, changes in LV systolic function were minimal with mean left ventricular ejection fraction (LVEF) decreasing from 39% at baseline to 34% after chemotherapy. None of the dexrazoxane-treated patients experienced symptomatic heart failure or elevated biomarkers (cardiac troponin I or brain natriuretic peptide). Of the three patients treated without dexrazoxane, two received doxorubicin (mean dose, 210 mg/m2), and one received daunorubicin (540 mg/m2). Anthracycline therapy resulted in a marked reduction in LVEF from 42.5% at baseline to 18%. All three developed symptomatic heart failure requiring hospitalization and intravenous diuretic therapy. Two of them died from cardiogenic shock and multi-organ failure.

CONCLUSION

The concomitant administration of dexrazoxane in patients with preexisting cardiomyopathy permitted successful delivery of anthracycline-based chemotherapy without cardiac decompensation. Larger prospective trials are warranted to examine the use of dexrazoxane as a cardioprotectant in patients with preexisting cardiomyopathy who require anthracyclines.

Occurrence of Treatment-Related Cardiotoxicity and Its Impact on Outcomes Among Children Treated in the AAML0531 Clinical Trial: A Report From the Children's Oncology Group

PURPOSE

Late cardiotoxicity after pediatric acute myeloid leukemia therapy causes substantial morbidity and mortality. The impact of early-onset cardiotoxicity on treatment outcomes is less well understood. Thus, we evaluated the risk factors for incident early cardiotoxicity and the impacts of cardiotoxicity on event-free survival (EFS) and overall survival (OS).

METHODS

Cardiotoxicity was ascertained through adverse event monitoring over the course of follow-up among 1,022 pediatric patients with acute myeloid leukemia treated in the Children's Oncology Group trial AAML0531. It was defined as grade 2 or higher left ventricular systolic dysfunction on the basis of Common Terminology Criteria for Adverse Events (version 3) definitions.

RESULTS

Approximately 12% of patients experienced cardiotoxicity over a 5-year follow-up, with more than 70% of incident events occurring during on-protocol therapy. Documented cardiotoxicity during on-protocol therapy was significantly associated with subsequent off-protocol toxicity. Overall, the incidence was higher among noninfants and black patients, and in the setting of a bloodstream infection. Both EFS (hazard ratio [HR], 1.6; 95% CI, 1.2 to 2.1; P = .004) and OS (HR, 1.6; 95% CI, 1.2 to 2.2, P = .005) were significantly worse in patients with documented cardiotoxicity. Impacts on EFS were equivalent whether the incident cardiotoxicity event occurred in the absence (HR, 1.6; 95% CI, 1.1 to 2.2; P = .017) or presence of infection (HR, 1.6; 95% CI, 1.0 to 2.7; P = .069) compared with patients without documented cardiotoxicity. However, the reduction in OS was more pronounced for cardiotoxicity not associated with infection (HR, 1.7; 95% CI, 1.2 to 2.5; P = .004) than for infection-associated cardiotoxicity (HR, 1.3; 95% CI, 0.7 to 2.4; P = .387).

CONCLUSION

Early treatment-related cardiotoxicity may be associated with decreased EFS and OS. Cardioprotective strategies are urgently needed to improve relapse risk and both short- and long-term mortality outcomes.