Phase 3, 2-arm, randomized, open label trial. Patients will be randomized to receive bosutinib or imatinib for the duration of the study.
The study will be open for enrollment until the planned number of approximately 500 Philadelphia Chromosome Positive (Ph+) patients have been randomized (approximately 250 Ph+ patients in each treatment arm; a total of approximately 530 Ph+ and Ph- patients). All patients will be treated and/or followed for approximately 5 years (240 weeks) after randomization until the study has closed. Patients who discontinue study therapy early due to disease progression or intolerance to study medication will continue to be followed yearly for survival for up to approximately 5 years (240 weeks) after randomization.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
536
Bosutinib (Bosulif®) is an orally bioavailable, potent, multi-targeted, dual Src-Abl tyrosine kinase inhibitor (TKI) that has been approved for the treatment of adult patients with Philadelphia positive (Ph+) chronic phase (CP), accelerated phase (AP) and blast phase (BP) chronic myelogenous leukemia (CML) previously treated with other TKI inhibitor therapy.\[1\] This study will investigate the use of bosutinib as first-line treatment for patients with Ph+ CP CML.
Imatinib mesylate (referred to in this protocol as imatinib) is an inhibitor of the BCR-ABL kinase and been the standard first-line therapy for patients with chronic-phase CML. Imatinib was granted approval by the European Commission in November 2001 and by the FDA in December 2002 for the treatment of newly diagnosed patients with CP Ph+ CML based on results from the IRIS trial. Imatinib is considered the standard of care for both first-line and later line settings, and consequently is an appropriate active comparator.
Percentage of Participants With Major Molecular Response (MMR) at Month 12
MMR was defined as a ratio of breakpoint cluster region to abelson (BCR-ABL/ABL) less than or equal to (\<=) 0.1 percent (%) on the international scale (IS) (greater than or equal to \[\>=\] 3 log reduction from standardized baseline in ratio of BCR-ABL to ABL transcripts \[\>=3000 ABL required\]) by quantitative reverse transcriptase polymerase chain reaction (RT-qPCR). The percentage of participants with MMR at Month 12 are reported.
Time frame: Month 12
Percentage of Participants With Major Molecular Response (MMR) Up to Month 18
MMR was defined as a ratio of BCR-ABL/ABL \<=0.1% on the international scale (\>=3 log reduction from standardized baseline in ratio of BCR-ABL to ABL transcripts \[\>=3000 ABL required\]) by quantitative RT-qPCR. The percentage of participants with MMR for up to Month 18 are reported.
Time frame: Up to Month 18
Kaplan-Meier Estimate of Probability of Retaining Major Molecular Response (MMR) at Month 48
The Kaplan-Meier curve was generated based on the first date of MMR until the date of the confirmed loss of MMR or censoring, objectively documented, for responders only. Confirmed loss of MMR was BCR-ABL/ABL IS ratio \>0.1% in association with a \>=5-fold increase in BCR-ABL/ABL IS ratio from the lowest value achieved up to that time-point confirmed by a second assessment at least 28 days later. Treatment discontinuation due to suboptimal response/treatment failure, progressive disease (PD) or death due to PD within 28 days of last dose were considered confirmed loss of MMR. PD was defined as disease progression to accelerated phase (AP) or blast phase (BP) CML.
Time frame: Month 48
Percentage of Participants With Complete Cytogenetic Response (CCyR) Up to Month 12
Complete Cytogenetic Response (CCyR) was based on the prevalence of Ph+ metaphases among cells in metaphase on a bone marrow (BM) aspirate. CCyR was achieved when there was 0% Ph+ metaphases among cells in a BM sample when at least 20 metaphases from a BM sample were analyzed, or MMR if no BM was available. The percentage of participants with CCyR for up to Month 12 are reported.
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Time frame: Up to Month 12
Kaplan-Meier Estimate of Probability of Retaining Complete Cytogenetic Response (CCyR) at Month 48
The Kaplan-Meier curve was generated based on the first date of CCyR until the date of the confirmed loss of CCyR or censoring, objectively documented, for responders only. Confirmed loss of CCyR was the presence of at least one Ph+ metaphase confirmed by a second assessment at least 28 days later. Treatment discontinuation due to suboptimal response/treatment failure, PD or death due to PD within 28 days of last dose were considered confirmed loss of CCyR. PD was defined as disease progression to AP or BP CML.
Time frame: Month 48
Cumulative Incidence of Event Free Survival (EFS) Events
EFS was defined as time from randomization to death due to any cause, transformation to AP or BP at any time, confirmed loss of complete hematologic response (CHR), confirmed loss of CCyR or censoring. Loss of CHR was defined as a hematologic assessment of non-CHR (chronic phase, AP, or BP) confirmed by 2 assessments at least 4 weeks apart. Loss of CHR was defined as appearance of any of the following: WBC count that rises to \>20.0\*10\^9/L, platelet count rises to \>=600\*10\^9/L, appearance of palpable spleen or other extramedullary involvement proven by biopsy, appearance of 5% myelocytes in peripheral blood, appearance of blasts or promyelocytes in peripheral blood. Loss of CCyR was defined as at least 1 Ph+ metaphase from analysis of \<100 metaphases confirmed by follow up cytogenetic analysis after 1 month. Cumulative incidence of EFS was defined as percentage of participants with EFS event at Month 60 and was adjusted for competing risk of treatment discontinuation without event.
Time frame: Up to Month 60
Overall Survival (OS) Rate
OS was defined as the time (in months) from randomization to the occurrence of death due to any cause or censoring. Kaplan-meier analysis was used for determination of OS. Percentage of participants who were alive were estimated in this outcome measure.
Time frame: Up to Month 60