Interestingly upon treatment pause (during an episode of heart failure subsequently deemed unrelated to asciminib) there was a rapid rise in BCR::ABL1 IS level, with a fall in the VAF of I502F-BSNV to below the level of detection, indicating relative outgrowth of I502F harbouring cells by the non-mutated BCR::ABL1 population. This evidence concerns the gene BCR and heart failure.