AML in remission, originating from MDS-RARS-T, expands the underlying JAK2 V617F mutated clone

A mutation in the JAK2 gene is commonly found in patients with MPN, which can sometimes lead to secondary AML. In this case study, we are reporting on an interesting case of secondary AML originating from MDS-RARS-T. The patient had no gross chromosomal changes, and we found that he was JAK2 V617F-mutated. His BM showed 53% of myeloid blasts. After the induction of combined therapy of Venetoclax and Azacytidine, a complete remission of the disease was achieved. However, instead of the expected decrease in the mutated JAK2 alleles, we documented a rise from the initial 55% to 79% of mutated alleles. This can be explained by the fact that treatment for AML targets only one subclone.