ETV6::RUNX1 Acute Lymphoblastic Leukemia: how much therapy is needed for cure?

Recent trials show 5-year survival rates >95% for ETV6::RUNX1 Acute Lymphoblastic Leukemia (ALL). Since treatment has many side effects, an overview of cumulative drug doses and intensities between eight international trials is presented to characterize therapy needed for cure. A meta-analysis was performed as a comprehensive summary of survival outcomes at 5 and 10 years. For drug dose comparison in non-high risk trial arms, risk group distribution was applied to split the trials into two groups: trial group A with ~70% (range: 63.5-75%) of patients in low risk (LR) (CCLSG ALL2004, CoALL 07-03, NOPHO ALL2008, UKALL2003) and trial group B with ~45% (range: 38.7-52.7%) in LR (AIEOP-BFM ALL 2000, ALL-IC BFM ALL 2002, DCOG ALL10, JACLS ALL-02). Meta-analysis did not show evidence of heterogeneity between studies in trial group A LR and medium risk (MR) despite differences in treatment intensity. Statistical heterogeneity was present in trial group B LR and MR. Trials using higher cumulative dose and intensity of asparaginase and pulses of glucocorticoids and vincristine showed better 5-year event-free survival but similar overall survival. Based on similar outcomes between trials despite differences in therapy intensity, future trials should investigate, to what extent de-escalation is feasible for ETV6::RUNX1 ALL.

The Prognostic Effect of IKZF1 Deletions in ETV6::RUNX1 and High Hyperdiploid Childhood Acute Lymphoblastic Leukemia.

IKZF1 deletions are an established prognostic factor in childhood acute lymphoblastic leukemia (ALL). However, their relevance in patients with good risk genetics, namely ETV6::RUNX1 and high hyperdiploid (HeH), ALL remains unclear. We assessed the prognostic impact of IKZF1 deletions in 939 ETV6::RUNX1 and 968 HeH ALL patients by evaluating data from 16 trials from 9 study groups. Only 3% of ETV6::RUNX1 cases (n = 26) were IKZF1-deleted; this adversely affected survival combining all trials (5-year event-free survival [EFS], 79% versus 92%; P = 0.02). No relapses occurred among the 14 patients with an IKZF1 deletion treated on a minimal residual disease (MRD)-guided protocols. Nine percent of HeH cases (n = 85) had an IKZF1 deletion; this adversely affected survival in all trials (5-year EFS, 76% versus 89%; P = 0.006) and in MRD-guided protocols (73% versus 88%; P = 0.004). HeH cases with an IKZF1 deletion had significantly higher end of induction MRD values (P = 0.03). Multivariate Cox regression showed that IKZF1 deletions negatively affected survival independent of sex, age, and white blood cell count at diagnosis in HeH ALL (hazard ratio of relapse rate [95% confidence interval]: 2.48 [1.32-4.66]). There was no evidence to suggest that IKZF1 deletions affected outcome in the small number of ETV6::RUNX1 cases in MRD-guided protocols but that they are related to higher MRD values, higher relapse, and lower survival rates in HeH ALL. Future trials are needed to study whether stratifying by MRD is adequate for HeH patients or additional risk stratification is necessary.

Socioeconomic position and maintenance therapy in children with acute lymphoblastic leukemia: A national cohort study.

BACKGROUND: Socioeconomic differences in survival among children with acute lymphoblastic leukemia (ALL) have been reported in high-income countries and there is an unmet need for strategies to identify vulnerable patient subgroups. Reported differences in survival for children from families with different socioeconomic positions seem to arise when starting maintenance therapy. This could reflect reduced physician's compliance or family adherence to maintenance therapy. METHODS: This nationwide cohort study with extensive monitoring of systemic methotrexate (MTX)/6-mercaptopurine (6MP) dosing and metabolite levels, retrospectively investigated 173 Danish children treated according to The Nordic Society for Pediatric Hematology and Oncology ALL2008 protocol from 2008 to 2016. RESULTS: Significantly lower prescribed doses of MTX and 6MP were seen in the children in families with short parental education (short vs. medium vs. higher education: mMTX: 13.8, 16.2, and 18.6 mg/m2 /week; p < .01; m6MP: 47.4, 64.9, and 66.1 mg/m2 /day; p = .03) or parents unemployed/not in workforce (unemployed/not in workforce vs. mixed vs. at work: mMTX: 15.0, 19.9, and 17.2 mg/m2 /week; p < .01; m6MP: 54.8, 72.0, and 65.1 mg/m2 /day; p < .01). When assessing family adherence by analyzing MTX and 6MP metabolite levels, including per prescribed dose of MTX and 6MP, we found no significant differences by levels of parental education, affiliation to work market, or income (p > .05 for all comparisons). CONCLUSIONS: These results indicate that inferior physician compliance to protocol recommendations on drug dosage rather than families' adherence to therapy may contribute to the association between socioeconomic position and cure rates in childhood ALL, although precise mechanisms remain to be explored.