P210 | LONG TERM OUTCOME OF CML PATIENTS TREATED WITH IMATINIB FRONT LINE

Background:Imatinib (Ima) has revolutionized the treatment of chronic myeloid leukemia.2nd generation TKIs induce faster and deeper molecular response but do not improve significantly overall survival. Methods:We conducted a monocentric,retrospective study to evaluate the outcome of patients (pts) treated with Ima front line for at least 4 years.46 pts (26 M/20 F median age 57,(15-84)) took Ima 400 mg front line. Molecular response has been monitored every 3 months by Real Time PCR.In case of failure or loss of response,Nilotinib or Dasatinib were used. Results:12 pts experienced a 2nd line of therapy,6 due to failure and 6 for loss of response.One pt changed therapy after 6 months, 4 pts after one year, 2 pts after 2 years, 3 pts after 3 years and 2 after 4 years. 34/46 pts continued treatment with Ima with a median follow up of 10.5 years (4-23). No pt progressed to accelerated/blastic phase. All of them reached at least a MMR,28 pt reached at least MR4.0.No grade 3-4 toxcities have been reported.4 pts discontinued therapy for TFR,2 of them maintained TFR while the others two achieved again a MMR after re.introduction of Ima. To date 8 pts are in MMR, 9 in MR4 and 17 in MR4.5 22 pts have reduced the dose of Ima (2 pts took 100 mg,10 took 200 mg and 10 took 300 mg.The median time of therapy with reduced dose is 35 months (6-96)). Starting from the 4th year of therapy no pt has lost MR3.Even pts who reduced the dose of Ima have maintained response, none have had an increase greater than 0.5 log of BCR/ABL. Conclusions Ima is confirmed to be effective and well tolerated. 12/46 pts experienced resistance or loss of response, but this always occurred during first 4 years of treatment.After this period, all pts maintained or deepened the initial response, without late toxicities.In 64% of pts, it was possible to reduce the dose of Ima,without compromising the response. So pts who have a good initial response to Ima and who do not lose it during the first 3-4 years of therapy could be candidates for a long survival without need to change therapy and most likely could not have had a better response if treated in the first line with next-generation TKIs, Few pts suspended therapy for TFR, although many of them had reached a stable MR4 or 4.5. This was due to the preference for a low-dose therapy, well tolerated and in all reassuring,compared to the decision of complete interruption,emotionally more involving and with the need for frequent monitoring.