Correlation of Different Responses to Imatinib on Survival of Patients (pts) with Chronic Myelogenous Leukemia (CML) in Accelerated (AP) and Blast Phase (BP).

Abstract

Imatinib has remarkable activity in CML in all phases, with high rates of hematologic and cytogenetic response. However, in AP and BP responses are frequently less than complete hematologic remission (CHR), including partial hematologic remission (PHR) and return to chronic phase (second CP). The objective of this study was to investigate whether different responses to imatinib conferred a survival advantage in pts with CML in AP and BP. We evaluated 214 pts in AP and 76 pts in BP (11 lymphoid, 63 myeloid, 2 unclassified) treated with imatinib. Median age for AP pts was 49 yrs (range: 22–82 yrs) and for BP, 54 yrs (19–75 yrs). With a median follow-up of 49 months (1.9–67.5 months), 82 (38%) AP and 66 (87%) BP pts have died. A CHR and major cytogenetic (CG) response (MCR) have been achieved in 87% and 53% of AP pts, and 37% and 14% of BP pts, respectively. For AP pts the median overall survival (OS) and progression free survival (PFS) were 65 and 49 months, respectively. In BP pts, median OS and PFS were 7 and 3 months. The OS by best response to imatinib was as follows:ResponseNo. (%)Median OS (months)p valueMedian PFS (months)p valueAccelerated phaseCG CR96 (45)Not reached<0.0001Not reached<0.0001CG PR13 (6)4328CG minor13 (6)4831CHR57 (27)3422PHR16 (7)146Resistant11 (5)53Blast PhaseCG CR6 (8)Not reached<0.0001Not reached<0.0001CG PR + minor8 (11)125CHR + PHR12 (16)1311Second CP6 (8)94Marrow CR/PR9 (12)54Resistant25 (33)42CG CR=complete CG response (Ph=0%), CG PR=partial CG response (Ph<35%), CG minor=minor CG response (Ph=35–95%), Marrow CR/PR=marrow complete/partial responseWe conclude that although cytogenetic responses confer the most survival advantage in AP and BP after imatinib therapy, hematologic responses are associated with a survival benefit.