A Multicenter Phase 3, Open-Label Study of Bosutinib Versus Imatinib in Adult Patients With Newly Diagnosed Chronic Phase Chronic Myelogenous Leukemia

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.

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.

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.

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.

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.

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.

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.

CCyR was based on the prevalence of Ph+ metaphases among cells in metaphase on a 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. Trough plasma concentration of participants who had CCyR are presented in this outcome measure.

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) by quantitative RT-qPCR. Trough plasma concentration of participants who had MMR are presented in this outcome measure.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. AE was assessed according to maximum severity grading based on National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Grade 1= mild; Grade 2= moderate; within normal limits, Grade 3= severe or medically significant but not immediately life-threatening; Grade 4= life-threatening or disabling; urgent intervention indicated; Grade 5= death. Trough plasma concentration of participants who had grade 1 or higher AE are presented in this outcome measure. Data of plasma concentration is reported separately for each preferred term of AE.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. AE was assessed according to maximum severity grading based on NCI CTCAE version 4.0. Grade 1= mild; Grade 2= moderate; within normal limits, Grade 3= severe or medically significant but not immediately life-threatening; Grade 4= life-threatening or disabling; urgent intervention indicated; Grade 5= death. Trough plasma concentration of participants who had grade 3 or higher AE are presented in this outcome measure. Data of plasma concentration is reported separately for each preferred term of AE.

Criteria for vital signs abnormalities: systolic blood pressure <80 millimeter of mercury (mmHg), >210 mmHg; diastolic blood pressure <40 mmHg, >130 mmHg; heart rate <40 beats per minute (bpm), >150 bpm; temperature <32 degree celsius, >40 degree celsius; weight >=10% increase from baseline, >=10% decrease from baseline. The number of participants with any vital sign abnormalities during On-treatment period are reported. On-Treatment was defined as values collected after the date of the first dose of test article until the last date of test article +28 days.

Laboratory parameters included hematological (haemoglobin, lymphocytes [absolute], neutrophils [absolute], platelets and leukocytes) and biochemistry (albumin, alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, amylase, bilirubin, creatinine kinase, calcium, creatinine, glucose, potassium, lipase, magnesium, phosphate, sodium, urate) parameters. Abnormalities in laboratory tests were graded by NCI CTCAE version 4.03 as Grade 1= mild; Grade 2= moderate; Grade 3= severe and Grade 4= life-threatening or disabling. The number of participants with laboratory test abnormalities were reported.

Criteria for ECG abnormalities included heart rate: increase of >15 bpm from baseline value and >=120 bpm, decrease of >15 bpm from baseline value and <=45 bpm; PR interval: change of >=20 msec from baseline value and >=220 milliseconds (msec); QRS interval >=120 msec; QTcB interval >500 msec, increase of >60 msec from baseline; >450 msec (Men) or >470 msec (Women). QT interval using Fridericia's correction (QTcF) >500 msec, increase of >60 msec from baseline, >450 msec (Men) or >470 msec (Women). The number of participants with ECG abnormalities during On-treatment period are reported. On-Treatment was defined as values collected after the date of the first dose of test article up until the last date of test article +28 days.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship.

An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. AE was assessed according to severity grading based on NCI CTCAE version 4.0. Grade 1 =mild; Grade 2 =moderate; Grade 3 =severe or medically significant but not immediately life-threatening, hospitalization or prolongation of hospitalization indicated; Grade 4 =life-threatening or disabling, urgent intervention indicated; Grade 5 =death. Treatment-emergent events were events between first dose of study drug and up to 60 months that were absent before treatment that worsened relative to pretreatment state. If the same participant in a given treatment had more than 1 adverse event, only the maximum CTCAE was reported.