Peng Ji

Objectives This study assesses the clinical significance of additional cytogenetic abnormalities (ACAs) and/or the deletion of 3′ CBFB (3′ CBFB del ) resulting in unbalanced CBFB::MYH11 fusion in acute myeloid leukemia (AML) with inv (16)/t(16;16)/ CBFB::MYH11 . Methods We retrospectively evaluated the clinicopathologic features of 47 adult de novo AML with inv (16)/t(16;16)/ CBFB::MYH11 fusion. There were 44 balanced and 3 unbalanced CBFB::MYH11 fusions. Given the low frequency of unbalanced cases, the latter group was combined with 19 published cases ( N = 22) for statistic and meta‐analysis. Results Both balanced and unbalanced cases were characterized by frequent ACAs (56.5% and 72.7%, respectively), with +8, +22, and del(7q) as the most frequent abnormalities. The unbalanced group tends to be younger individuals ( p = .04) and is associated with a lower remission rate ( p = .02), although the median overall survival (OS) was not statistically different ( p = .2868). In the balanced group, “ACA” subgroup had higher mortality ( p = .013) and shorter OS ( p = .011), and patients with relapsed disease had a significantly shorter OS ( p = .0011). Cox multivariate regression analysis confirmed that ACAs and history of disease relapse are independent risk factors, irrespective of disease relapse status. In the combined cohort, cases with ACAs had shorter OS than those with “Sole” abnormality ( p = .0109). Conclusions ACAs are independent high‐risk factors in adult AML with inv (16)/t(16;16)/ CBFB::MYH11 fusion and should be integrated for risk stratification in this disease. Larger studies are needed to assess the clinical significance of the unbalanced CBFB::MYH11 fusion resulting from the 3′ CBFB del .