Imatinib 400 mg in Early Chronic Phase CML: Results of a Multicentric, Prospective Non Academical Observational Study (by the GIMEMA CML Working Party).

Imatinib 400 mg (SD) is the established first line treatment of chronic myeloid leukemia (CML) in chronic phase. The efficacy of imatinib in early chronic phase has been demonstrated by phase 2 and 3 controlled trials like the IRIS study (O’ Brien et al NEJM 348:11, 2004). Large multicentric studies aimed to evaluate the impact of imatinib 400 mg outside strictly monitored frameworks are not yet available. The GIMEMA (Gruppo Italiano Malattie Ematologiche dell’Adulto) CML Working Party opened in January, 2004, an observational study (serial n. CML/023) to investigate the efficacy of imatinib SD in newly diagnosed CML pts. Clinical and anagraphical data were collected through a web-based system. Peripheral blood samples for quantitative molecular analysis (RT-Q-PCR, Bcr-Abl/Abl × 100 - Taqman) were centralized in Bologna. Overall, 55 italian centers enrolled 367 (359 evaluable) newly diagnosed CML pts in chronic phase between Jan 2004 and Jan 2006. Median age was 50 yrs (range 18–84), 220 male and 139 females. Sokal risk at diagnosis was low, intermediate and high in 221 (62%), 123 (34%), 15 (4%) pts, respectively. 359 pts are evaluable for response at 3 months, 310 at 6 months and 187 at 12 months. The median observation time is 12 months. At 3 months, 94% of the pts reached a stable CHR. At 6 months, 80% of evaluable cases obtained a complete cytogenetic response (100% Ph-neg, CCgR). A major molecular response (MMolR) defined as a Bcr-Abl/Abl × 100 ratio < 0.1%, was shown in 52% of CCgR pts. At 12 months, the CCgR rate was 87% and the MMolR rate in CCgR pts was 63%. At 12 months, 3% of CCgR cases showed an undetectable level of transcript (ratio Bcr-Abl/Abl × 100 < 0,0001). With this short observation period, only 4 pts (1,1%) progressed to accelerated/blastic phase. Limiting the observation to low Sokal risk, at 12 months 221 such pts got a CCgR and MMol rates of 88% and 62%, respectively; 201 low Sokal risk pts were enrolled in the IRIS trial: at 12 months CCgR and MMolR (reduction of Bcr-Abl/Bcr ratio level > 3 logs) rates were 76% and 66%, respectively ( (T Hughes et al, NEJM 349:15, 2003). This study confirns that imatinib is efficacious and manageable, confirming and improving the results of the IRIS trial.