Page 67 - 2021_12-Haematologica-web

A centralized NGS diagnostic platform for AML
Figure 5. Age-related mutational profile. P- values (P) for statistically significant results are shown. ITD: internal tandem duplication; PM: point mutations.
clonal size of TP53 variants, determined by VAF and chro- mosomal aberrations (del 17p), could discriminate patients with worse prognosis among TP53 mutated AML.29,30
Our study allowed to observe differences in the muta- tional profile of relapsed/refractory patients as compared to newly diagnosed/untreated subjects. Interestingly, RUNX1 variants were more frequent among refractory AML patients, which is consistent with previously reported poor- er outcomes after intensive chemotherapy and its associa- tion with older age.31 The same was observed with SFRS2, depicting poorer outcomes when commutated with IDH232 which was highly associated in our cohort. NPM1 variants were significantly less frequent in refractory patients, as compared to newly diagnosed or relapsed, reflecting the known high complete remission rates in this setting.33,34 Interestingly, IDH variants were the most frequent alter- ation at relapse, suggesting that they are associated with higher relapse risk,35 but also have more possibilities to obtain an initial response with front-line therapies.18,36
We analyzed 35 patients with paired samples at diagnosis versus relapse/refractory setting, confirming some findings from scarce studies on clonal evolution: i) as a founder vari- ant, NPM1 was very stable,37,38 ii) DNMT3A variants were very stable, probably due to its early acquisition and
preleukemic occurrence,39,40 as well as their persistence dur- ing remission and disease progression,41 and iii) activating signaling pathways genes were unstable (FLT3, NRAS, KRAS, BRAF, KIT and PTPN11). This is particularly relevant for the management of patients who acquire FLT3 muta- tions during relapse and refractoriness which may benefit from second generation inhibitors such as gilteritinib, avail- able for the treatment of relapsed/refractory AML with FLT3 mutation.42,43 In line with the study by Kronke et al., we show that IDH2 variants were very stable, contrarily to IDH1, but numbers are low and should be cautiously inter- preted.38
The main limitation of our study is that, apart from age and disease phase, baseline clinical characteristics, treat- ment patterns, and outcomes, were not available for a minor proportion of patients at the time of this interim analysis of the NGS-AML trial. This is why the results here- in presented focused on the overall network building strat- egy, as well as in the cross-validation of samples and report- ing harmonization, showing a mutational landscape of AML consistent with the current knowledge. We should mention that our diagnostic platform has many areas of improvement: i) time to NGS reporting, which is longer than conventional molecular analysis (approximately 2-3
haematologica | 2021; 106(12)
3087