Tyrosine kinase inhibitor treatment monitoring is performed in order to evaluate the success of therapy and to allow specific changes in cases in which remission was not obtained, was lost after being achieved with or without drug interruption, when clonal evolution occurs despite therapy or when clonal abnormalities are detected in Ph-negative cells. It is recommended to perform marrow karyotyping at three or six months after starting therapy and then at six-month intervals until complete cytogenetic remission (CCR) is achieved. Once in CCR, quantitative real time PCR is the method of choice for monitoring, but karyotyping should be performed every year to detect loss of response, clonal evolution or clonal abnormalities in Ph-negative cells. In fact, only karyotyping can monitor the acquisition of clonal aberrations related to disease progression. In this article situations less frequently found, but deserving close monitoring, such as variant Ph, deletion on derivative chromosome 9q and clonal aberrations in Ph-negative cells are also discussed.
Philadelphia chromosome; cytogenetic monitoring; complete remission; del der(9q)
