An Extension Study to Determine the Safety and Anti-Leukemic Effects of Imatinib Mesylate in Adult Participants With Ph+ Leukemia

Hematologic response was evaluated from hematology measurements in the peripheral blood (PB) and bone marrow (BM) and assessments of extramedullary leukemic involvement (EMD) at physical examination. Response was defined as complete hematologic remission (CHR), no evidence of leukemia (NEL), or return to chronic phase (RTC).

Bone marrow (BM) cytogenetic analysis was required at baseline, after 12 weeks (visit 22) and after 24 weeks (visit 28) to evaluate Ph chromosome positivity. In several participants, this was also done after 4 and 8 weeks. Based on the percentage of Philadelphia chromosome positive (Ph+) cells = (positive cells/examined cells)x100, at each BM assessment the cytogenetic response was classified as: Complete, 0% Ph+ cells; Partial, >0 - 35% Ph+ cells; Minor, >35 - 65% Ph+ cells; Minimal, >65 - 95% Ph+ cells; None, >95% Ph+ cells; Not done: <20 metaphases were examined and/or response could not be assigned. Cytogenetic response was defined as confirmed complete or partial response. A BM sample was considered as assessable for cytogenetic response only if it contained ≥20 metaphases. However, an assessment of partial response was retained in a sample with <20 metaphases when it was immediately preceded or followed by a complete or partial response in another sample with ≥20 metaphases.

Time to response was defined for all participants as the time until first documented response (which was confirmed ≥4 weeks later).

Duration of response was defined as the time between first documented response (which was confirmed ≥4 weeks later) and the earliest date of the following: loss of response (when any of the criteria for response were no longer fulfilled); progression to blast crisis (≥30% blasts in peripheral blood or bone marrow, extramedullary involvement other than liver/spleen enlargement); discontinuation due to adverse event, laboratory abnormality, unsatisfactory therapeutic effect or death.

Progression to blast crisis was defined as ≥30% blasts in peripheral blood or bone marrow or as extramedullary involvement other than liver or spleen enlargement.

To evaluate overall survival, all participants were followed after the last dose of study drug every month for the first three months and thereafter every three months until death. Overall survival was calculated for all participants as the time between start of treatment and death due to any reason. The time was censored at the date of last contact for participants who discontinued treatment and were in survival follow-up. For participants without survival follow-up information, the time was censored at last available visit/treatment date.

To evaluate overall survival, all participants were followed after the last dose of study drug every month for the first three months and thereafter every three months until death. Overall survival was calculated for all participants as the time between start of treatment and death due to any reason. The time was censored at the date of last contact for participants who discontinued treatment and were in survival follow-up. For participants without survival follow-up information, the time was censored at last available visit/treatment date.