Adverse cytogenetics trump molecular risk in NPM1-mutated AML

A pooled analysis suggests adverse cytogenetics are a key factor negatively impacting outcomes in patients with NPM1^mut/FLT3-ITD^neg/low acute myeloid leukemia (AML).

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In patients with adverse chromosomal abnormalities, NPM1 mutational status was found not to confer a favorable outcome. The findings suggest cytogenetic risk outweighs molecular risk in patients with NPM1 mutations and the FLT3-ITD^neg/low genotype.

“Patients carrying adverse-risk cytogenetics shared a virtually identical unfavorable outcome, regardless of whether the otherwise beneficial NPM1^mut/FLT3-ITD^neg/low status was present. The type of the adverse chromosomal abnormality did not seem to influence this effect, although low numbers might obscure detection of heterogeneity among individual aberrations,” Linus Angenendt, MD, of University Hospital Munster (Germany) and colleagues, wrote in the Journal of Clinical Oncology.

The researchers retrospectively analyzed 2,426 patients with NPM1^mut/FLT3-ITD^neg/low AML. Of these, 17.6% had an abnormal karyotype, and 3.4% had adverse-risk chromosomal aberrations.

Prior to analysis, individual patient data were pooled from nine international AML study group registries or treatment centers.

After analysis, the researchers found that adverse cytogenetics were associated with inferior complete remission rates (66.3%), compared with in patients with normal karyotype or intermediate-risk cytogenetic abnormalities (87.7% and 86.0%, respectively; P less than .001). The complete remission rates for the NPM1^mut/FLT3-ITD^neg/low AML adverse cytogenetics group was similar to patients with NPM1^wt/FLT3-ITD^neg/low and adverse cytogenetic abnormalities (66.3% vs. 57.5%).

Five-year event-free survival rates and overall survival rates were also lower in patients with NPM1^mut/FLT3-ITD^neg/low AML and adverse cytogenetics, compared with patients with normal karyotype or intermediate-risk cytogenetic abnormalities (P less than .001).

“Even though the combination of an NPM1 mutation with these abnormalities is rare, the prognostic effect of adverse cytogenetics in NPM1^mut AML has important implications for postremission treatment decisions, in particular, the current recommendation that patients who are NPM1^mut/FLT3-ITD^neg/low not receive allogeneic hematopoietic stem cell transplantation (HSCT), given their presumed low risk of relapse might be altered if the adverse karyotype increased the risk,” they wrote.

The type of chromosomal aberration did not appear to impact this effect, but the small sample size may have hindered the ability to detect a difference between different abnormalities, the researchers noted.

One key limitation of the study was the retrospective design. As a result, in patients with an abnormal karyotype, some genetic analyses could have been underutilized.

“These results demand additional validation within prospective trials,” the researchers concluded.

The study was funded by the University of Munster Medical School, the German Research Foundation, the French government, the Ministry of Health of the Czech Republic, and others. The authors reported financial affiliations with numerous pharmaceutical companies.

SOURCE: Angenendt L et al. J Clin Oncol. 2019 Oct 10;37(29):2632-42.