Imatinib High Dose (800 mg): Results of a Phase II Trial of the GIMEMA (Gruppo Italiano Malattie Ematologiche Dell’Adulto) CML Working Party in Intermediate Sokal Risk Patients and Status-of-the-Art of an Ongoing Multinational, Prospective Randomized Trial of Imatinib Standard Dose (400 mg Daily) vs High Dose (800 mg Daily) in High Sokal Risk Patients.

Imatinib has become the treatment of choice for CML. The standard dose (SD) for CP CML is 400 mg daily: results are less favourable in pts at high or intermediate Sokal risk vs low Sokal risk ones. In intermediate Sokal risk, the IRIS trial (Hughes et al NEJM 349:15, 2003 ) reported at 12 mos a complete cytogenetic response (CCgR- 0% Ph-pos) rate of 67% and a major molecular response (MMolR) rate of 45%. Pre-clinical and clinical data suggest that high doses (HD - 800 mg daily) of ima may be more effective. The GIMEMA CML Working party is conducting a phase II, multi-istitutional prospective study (serial n. CML/021) to investigate the effects of imatinib HD in intermediate Sokal risk. Between Jan, 2004 and May, 2005, 25 centers enrolled 82 pts (80 eval); median age 56 yrs (26–79). Pts evaluable at 3,6 and 12 mos are 80, 77 and 65, respectively. The median observation time is 12 mos. At 3 and 6 mos, 83% and 97% of the pts reached a stable CHR. At 6 mos, 86% obtained a CCgR and 53% of CCgR pts a MMolR (Bcr-Abl/Abl × 100 ratio < 0.1%). At 12 mos, the CCgR rate was 90% and the MMolR rate was 57%. One patient progressed to accelerated/blastic phase. The compliance to HD treatment was good: at 3, 6 and 12 mos 55%, 52% and 52% of the pts received a median daily dose of imatinib > 600 mg. Non hematopoietic AEs accounted for the great majority of dose reductions. The results of this trial further indicate that imatinib HD induces higher and more rapid responses in intermediate Sokal risk CML pts in early chronic phase, being superior to the results obtained with SD (IRIS) and in the range of the MD Anderson results (Kantarjian et al Blood 2004 103:2873). A second project is reserved to high Sokal risk CML pts in early CP: a multinational group, within EuropeanLeukemianet CML WP, is conducting a phase III trial (1:1) of imatinib 400 mg vs 800 mg. By July 31, 2005, 141 patients have been enrolled: GIMEMA (88 pts), Nordic CML Study Group (Sweden, Denmark, Norway and Finland) (25 pts), Turkey (25 pts) and Israel (3 pt).