Contributions
Abstract: EP449
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Clinical
Background
The detection of mutations in genes known to be associated with hematologic malignancies has been termed clonal hematopoiesis (CH). CH detected in cryopreserved cells of patients (pts) undergoing autologous stem-cell transplantation (ASCT) for hematologic neoplasia has been associated with an increased risk of therapy-related myeloid neoplasm (t-MN), but its role in the development of t-MN and the variations of the mutational profile occurring in the single pt between ASCT and t-MN are still partially known.
Aims
The primary objective of this study was the comparison of the mutational profile and of variant allele frequency (VAF) of mutated genes at leukapheresis and at t-MN in ASCT pts who actually developed t-MN. The mutational profile at leukapheresis was also compared with that of matched control ASCT pts, who did not develop t-MN.
Methods
Among the entire cohort of lymphoma and myeloma pts treated with high-dose chemotherapy and ASCT at the Hematology Dpt of Spedali Civili in Brescia between 2001 and 2019, we selected pts who developed t-MN after ASCT and had available backup cryopreserved CD34+ stem cells. Pts who did not experience t-MN, matched for demographic and clinical characteristics, acted as controls. Pre- and post-ASCT samples were sequenced on the Genestudio S5 Prime, using an On-Demand NGS panel designed with Ion Ampliseq Designer software, that included 45 genes known to be associated with either CHIP, myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).
Results
Out of 1075 lymphoma or myeloma pts undergoing ASCT, 35 developed t-MN (3.3%). Frequency was significantly higher in lymphoma (27/592, 4.6%) than in myeloma (8/483, 1.7%) (p=0.0088). In 19 of them (lymphoma: n. 16; myeloma: n. 3), the mutational profile was assessed both at ASCT and at t-MN (AML: n.8; MDS: n.11). Their median follow up was 6 years (range 2-14). A higher number of mutations of 20 genes was detected at t-MN diagnosis (n. 46 in 16/19 patients; 84%), as compared to ASCT (n. 16 in 11/19 patients; 58%;). Control pts had a significantly lower number of mutations at ASCT (n. 7 in 6/26; 23%) compared to pts developing t-MN (n. 16, in 11/19; 58%; p=0.029); median follow-up of controls was 7 years (range 3-13). Epigenetic regulation, including DNMT3A, and DNA repair gene mutations, specifically PPM1D, were most frequently mutated at ASCT. At t-MN mutations in these genes showed a modest increase and their VAF did not change except in one patient. Conversely, TP53 mutations were the most represented at t-MN (28% of total); they appeared de novo in 8 pts and VAF increased from 14% to 49% in the single pt with mutated TP53 also at ASCT. In addition, mutations in genes of intracellular signaling or encoding transcription factors (e.g. RAS, RUNX1) were also commonly detected at t-MN. They were absent in controls, whose mutations at ASCT also occurred mainly in epigenetic genes.
Conclusion
These data confirm that CH at ASCT is associated with a higher risk of developing t-MN. They also show that the mutational profile varies markedly between ASCT and t-MN. Epigenetic and DNA repair gene mutations are characteristic at ASCT and do not increase significantly at t-MN; they may represent a marker of genetic instability favoring the development of t-MN. Conversely, mutations of TP53 and transcription factor encoding or intracellular signaling genes appear more strictly associated with the pathogenesis of t-MN and their emergence may be promoted by the high-dose cytotoxic treatments delivered as conditioning regimens before ASCT.
Keyword(s): Therapy-related AML
Abstract: EP449
Type: E-Poster Presentation
Session title: Acute myeloid leukemia - Clinical
Background
The detection of mutations in genes known to be associated with hematologic malignancies has been termed clonal hematopoiesis (CH). CH detected in cryopreserved cells of patients (pts) undergoing autologous stem-cell transplantation (ASCT) for hematologic neoplasia has been associated with an increased risk of therapy-related myeloid neoplasm (t-MN), but its role in the development of t-MN and the variations of the mutational profile occurring in the single pt between ASCT and t-MN are still partially known.
Aims
The primary objective of this study was the comparison of the mutational profile and of variant allele frequency (VAF) of mutated genes at leukapheresis and at t-MN in ASCT pts who actually developed t-MN. The mutational profile at leukapheresis was also compared with that of matched control ASCT pts, who did not develop t-MN.
Methods
Among the entire cohort of lymphoma and myeloma pts treated with high-dose chemotherapy and ASCT at the Hematology Dpt of Spedali Civili in Brescia between 2001 and 2019, we selected pts who developed t-MN after ASCT and had available backup cryopreserved CD34+ stem cells. Pts who did not experience t-MN, matched for demographic and clinical characteristics, acted as controls. Pre- and post-ASCT samples were sequenced on the Genestudio S5 Prime, using an On-Demand NGS panel designed with Ion Ampliseq Designer software, that included 45 genes known to be associated with either CHIP, myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).
Results
Out of 1075 lymphoma or myeloma pts undergoing ASCT, 35 developed t-MN (3.3%). Frequency was significantly higher in lymphoma (27/592, 4.6%) than in myeloma (8/483, 1.7%) (p=0.0088). In 19 of them (lymphoma: n. 16; myeloma: n. 3), the mutational profile was assessed both at ASCT and at t-MN (AML: n.8; MDS: n.11). Their median follow up was 6 years (range 2-14). A higher number of mutations of 20 genes was detected at t-MN diagnosis (n. 46 in 16/19 patients; 84%), as compared to ASCT (n. 16 in 11/19 patients; 58%;). Control pts had a significantly lower number of mutations at ASCT (n. 7 in 6/26; 23%) compared to pts developing t-MN (n. 16, in 11/19; 58%; p=0.029); median follow-up of controls was 7 years (range 3-13). Epigenetic regulation, including DNMT3A, and DNA repair gene mutations, specifically PPM1D, were most frequently mutated at ASCT. At t-MN mutations in these genes showed a modest increase and their VAF did not change except in one patient. Conversely, TP53 mutations were the most represented at t-MN (28% of total); they appeared de novo in 8 pts and VAF increased from 14% to 49% in the single pt with mutated TP53 also at ASCT. In addition, mutations in genes of intracellular signaling or encoding transcription factors (e.g. RAS, RUNX1) were also commonly detected at t-MN. They were absent in controls, whose mutations at ASCT also occurred mainly in epigenetic genes.
Conclusion
These data confirm that CH at ASCT is associated with a higher risk of developing t-MN. They also show that the mutational profile varies markedly between ASCT and t-MN. Epigenetic and DNA repair gene mutations are characteristic at ASCT and do not increase significantly at t-MN; they may represent a marker of genetic instability favoring the development of t-MN. Conversely, mutations of TP53 and transcription factor encoding or intracellular signaling genes appear more strictly associated with the pathogenesis of t-MN and their emergence may be promoted by the high-dose cytotoxic treatments delivered as conditioning regimens before ASCT.
Keyword(s): Therapy-related AML