High-risk B-ALL subgroup has ‘outstanding outcomes’

The researchers also assessed EFS and OS among patients with favorable cytogenetics according to NCI risk group and MRD at days 8 and 29.

“One thing to point out is that, regardless of having favorable cytogenetics, those individuals who had end-induction MRD values of greater than 0.01% had inferior outcomes, so that was still a prognostic marker,” Dr Raetz said.

“And one thing that we were pleasantly surprised to see was that, among the NCI high-risk patients, those who had very rapid MRD responses—so less than 1% at day 8 in the blood and less than 0.01% in the marrow on day 29—had a 94.9% 5-year event-free survival and 98.1% overall survival.”

The researchers also divided this group according to age—patients younger than 10 and those 10 years or older. There was no significant difference in EFS or OS between the age groups (P=0.126 and P=0.411).

Standard-risk group

Among patients with <1% MRD on day 8 and <0.01% MRD on day 29, the EFS was 95.7% and the OS was 99.1%.

Among patients with ≥1% MRD on day 8 and <0.01% MRD on day 29, the EFS was 91.7% and the OS was 99.4%.

Among patients with any MRD on day 8 and ≥0.01% MRD on day 29, the EFS was 88.1% and the OS was 96.8%.

High-risk group

Among patients with <1% MRD on day 8 and <0.01% MRD on day 29, the EFS was 94.9% and the OS was 98.1%.

Among patients with ≥1% MRD on day 8 and <0.01% MRD on day 29, the EFS was 93.6% and the OS was 95.5%.

Among patients with any MRD on day 8 and ≥0.01% MRD on day 29, the EFS was 75.4% and the OS was 90.4%.

In closing, Dr Raetz said this study showed that real‐time classification incorporating clinical features, blast cytogenetics, and early response was feasible in a large group of patients enrolled on COG ALL trials and identified patients with varying outcomes for risk‐based treatment allocation.

She noted that early response by marrow morphology was not prognostic when MRD response was used and is therefore no longer used in COG studies.

And although favorable cytogenetic features were not prognostic in NCI high-risk B‐ALL patients in prior COG studies, the current study indicates that these patients can have “excellent outcomes” if they have no evidence of CNS leukemia and are rapid MRD responders. So these patients will not benefit from further chemotherapy intensification.