On the other hand, one could argue that the overall rate of CMR is lower than would be expected from the very rapid decline of leukemia burden, suggesting that in most patients the residual population of CML cells is beyond the reach of TKIs, consistent with the observation that primitive CML cells maintain viability despite TKI-induced inhibition of BCR-ABL [20]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.