Long-term results of imatinib mesylate therapy in philadelphia chromosome (Ph) positive chronic phase chronic myelogenous leukemia (CML) post interferon-a (IFN) failure M.D. Anderson experience in 261 patients

Abstract

6622 Background: The initial results of imatinib in Ph-positive CML in chronic phase post IFN failure were positive with a median follow up times of 17 months. The major cytogenetic (CG) response rate (Ph 5% (p<0.05) or prior hematologic resistance to IFN (p=0.01). Achieving any CG response at 3 months was associated with a 4-year survival rate of 95% (versus 78% for others; p=0.0001); the 4-year FFP rates were 94% versus 64%, respectively (p<0.0001). Achieving a major CG response at 6 months was associated with a 4-year survival rate of 95% (versus 81% for others; p=0.001); the 4-yr FFP rates were 94% versus 68% (p<0.0001). Among 167 patients achieving CG CR, 152 pts had quantitative PCR (QPCR) studies: 82 pts (49%; 31% total) had a major molecular response (QPCR= BCR-ABL/ABL <0.05%) and 38 pts (15%) had a complete molecular response (BCR-ABL undetectable). The 3-yr cumulative major molecular response rate was 55%, and complete molecular response rate 22%. Compared with a historical group of 131 similar patients in CML chronic phase post IFN failure treated with non-imatinib therapies, imatinib was associated with better 4-year survival rates (88%, versus 35% p<0.0001); this survival advantage for imatinib was confirmed by multivariate analysis (p<0.0001). Conclusions: The results with imatinib in CML chronic phase post IFN failure are improving and durable. Major and complete responses are now noted in a substantial proportion of patients with longer follow-up time. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis; Supergen