hrvatski

Monitoring CMLl patients responding to treatment with tyrosine kinase inhibitors with real-time quantitative polymerase chain reaction

Historically, chronic myeloid leukemia (CML) had many revolutional advances in therapy implementation. Discovery of new improved drugs like imatinib mesylate (IM) requires advances in technology in order to enable more precise assessment of response to therapy. Real-time quantitative polymerase chain reaction (RQ-PCR) provides an accurate measure of the degree of BCR-ABL transcripts reduction which correlates inversely with disease progression. The aim of this study was to enable a better assessment of the response of individual patients to treatment with IM and to evaluate the efficacy of a treatment protocol by using sensitive quantitative polymerase chain reaction measurement of BCR-ABL/ABL ratio in order to stratify patients according to risk of relapse and to individualize treatment protocol. The aim of the study was to quantitate BCR-ABL transcripts in CML patients and to monitor response to treatment with tyrosine kinase inhibitors. The study included total of 31 patients treated with IM. RNA was isolated from bone marrow or peripheral blood cells. RQ-PCR was performed according to EAC protocol using TaqMan technology (LightCycler, Roche) with ABL as housekeeping gene and BCR-ABL/ABL ratio was calculated. Standardized baseline was derived from BCR-ABL/ABL ratio obtained from untreated patients at diagnosis and was used for calculation of log reduction for all follow up samples. Patients were divided in groups according to calculated log reduction of BCR-ABL/ABL ratio in 18 months of IM therapy: group I - more than 3 log reduction, group II – less than 3 log reduction and group III – less than 18 months in follow up. Group I consisted of 11 patients who achieved and maintained MMoR for median time of 21 months. Only one patient from this group relapsed. Group II included 13 patients who had less than 3 log reduction in 18 months. Because of inadequate response to therapy, the change in treatment occured. Six patients proceeded with higher dose of IM (600 or 800 mg/day) with no significant changes in BCR-ABL/ABL ratio. One of these patients then started dasatinib therapy and in 9 months achieved MMoR. Other two patients on dasatinib achieved no more than 1 log reduction as well as one patient on nilotinib therapy unlike the other nilotinib patient who achieved 2, 2 log reduction in 5 months. The patient without any response to IM therapy underwent bone marrow transplantation with undetectable BCR-ABL transcript 11 months later. There were seven newly diagnosed CML patients in group III monitored for less than 18 months and therefore MMoR couldn't be estimated but using the same analogy as in first two groups, prediction of disease course could be possible. Our results show that RQ-PCR is mandatory for careful monitoring of response to treatment with tyrosine kinase inhibitors in order to ensure that an individual patient receives the proper treatment and to decide if and when a therapy should be changed.

chronic myeloid leukemia; imatinib mesylate; quantitative polymerase chain reaction; major molecular response

nije evidentirano

engleski

Monitoring CMLl patients responding to treatment with tyrosine kinase inhibitors with real-time quantitative polymerase chain reaction

Historically, chronic myeloid leukemia (CML) had many revolutional advances in therapy implementation. Discovery of new improved drugs like imatinib mesylate (IM) requires advances in technology in order to enable more precise assessment of response to therapy. Real-time quantitative polymerase chain reaction (RQ-PCR) provides an accurate measure of the degree of BCR-ABL transcripts reduction which correlates inversely with disease progression. The aim of this study was to enable a better assessment of the response of individual patients to treatment with IM and to evaluate the efficacy of a treatment protocol by using sensitive quantitative polymerase chain reaction measurement of BCR-ABL/ABL ratio in order to stratify patients according to risk of relapse and to individualize treatment protocol. The aim of the study was to quantitate BCR-ABL transcripts in CML patients and to monitor response to treatment with tyrosine kinase inhibitors. The study included total of 31 patients treated with IM. RNA was isolated from bone marrow or peripheral blood cells. RQ-PCR was performed according to EAC protocol using TaqMan technology (LightCycler, Roche) with ABL as housekeeping gene and BCR-ABL/ABL ratio was calculated. Standardized baseline was derived from BCR-ABL/ABL ratio obtained from untreated patients at diagnosis and was used for calculation of log reduction for all follow up samples. Patients were divided in groups according to calculated log reduction of BCR-ABL/ABL ratio in 18 months of IM therapy: group I - more than 3 log reduction, group II – less than 3 log reduction and group III – less than 18 months in follow up. Group I consisted of 11 patients who achieved and maintained MMoR for median time of 21 months. Only one patient from this group relapsed. Group II included 13 patients who had less than 3 log reduction in 18 months. Because of inadequate response to therapy, the change in treatment occured. Six patients proceeded with higher dose of IM (600 or 800 mg/day) with no significant changes in BCR-ABL/ABL ratio. One of these patients then started dasatinib therapy and in 9 months achieved MMoR. Other two patients on dasatinib achieved no more than 1 log reduction as well as one patient on nilotinib therapy unlike the other nilotinib patient who achieved 2, 2 log reduction in 5 months. The patient without any response to IM therapy underwent bone marrow transplantation with undetectable BCR-ABL transcript 11 months later. There were seven newly diagnosed CML patients in group III monitored for less than 18 months and therefore MMoR couldn't be estimated but using the same analogy as in first two groups, prediction of disease course could be possible. Our results show that RQ-PCR is mandatory for careful monitoring of response to treatment with tyrosine kinase inhibitors in order to ensure that an individual patient receives the proper treatment and to decide if and when a therapy should be changed.

chronic myeloid leukemia; imatinib mesylate; quantitative polymerase chain reaction; major molecular response

nije evidentirano