This three-cohort, multi-stage, randomized, Phase II, multicenter trial will evaluate the safety and tolerability and estimate the efficacy of cobimetinib plus paclitaxel versus placebo plus paclitaxel in Cohort I, of cobimetinib plus atezolizumab plus paclitaxel in Cohort II, and of cobimetinib plus atezolizumab plus nab-paclitaxel in Cohort III in participants with metastatic or locally advanced, triple-negative adenocarcinoma of the breast who have not received prior systemic therapy for metastatic breast cancer (MBC). Participants may continue on study treatment until the development of progressive disease (PD) or the loss of clinical benefit, unacceptable toxicity, and/or consent withdrawal. The Cohort I target sample size is 12 participants for the safety run-in stage and approximately 90 participants in the expansion stage. Each of Cohorts II and III will consist of a safety run-in stage of approximately 15 participants followed by an expansion stage of approximately 15 participants.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
169
Cobimetinib will be administered orally at a dose of 60 milligrams (mg) per day, once a day, on Day 3 through Day 23 of each 28-day treatment cycle.
Paclitaxel will be administered at a dose of 80 milligrams per square meter (mg/m\^2) by intravenous (IV) infusion on Day 1, Day 8, and Day 15 of each 28-day cycle according to prescribing information.
Placebo matching to cobimetinib will be administered orally, once a day, on Day 3 through Day 23 of each 28 day treatment cycle.
Atezolizumab will be administered to Cohorts II and III at a dose of 840 mg IV every 2 weeks on Days 1 and 15 of each 28-day treatment cycle.
Nab-Paclitaxel will be administered to Cohort III according to the local prescribing information at a starting dose of 100 mg/m\^2 by IV infusion on Days 1, 8, and 15 of each 28 day cycle.
Cancer Specialists of North Florida
Jacksonville, Florida, United States
Mercy Hospital, a Campus of Plantation General Hospital
Miami, Florida, United States
Florida Hospital Cancer Inst
Orlando, Florida, United States
Florida Cancer Research Institute
Plantation, Florida, United States
Cancer Treatment Centers of America
Newnan, Georgia, United States
Cohort I: Progression-Free Survival, as Determined by Investigator Using Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1)
PFS was defined as the time from randomization to the first occurrence of disease progression or relapse, as determined by the investigator, using RECIST v1.1. As per RECIST v1.1, progressive disease (PD) is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (nadir), including baseline. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 millimeters (mm). The appearance of one or more new lesions is also considered progression.
Time frame: Randomization up to disease progression or relapse, whichever occurs first (up to approximately 2 years)
Cohort II, III: Percentage of Participants With Confirmed Overall Response (OR) (Partial Response [PR] or Complete Response [CR]), as Determined by the Investigator Using RECIST v1.1
OR was defined as the rate of a PR or CR occurring after randomization and confirmed \>=28 days later as determined by the investigator using RECIST v1.1. As per RECIST v1.1, CR is defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or nontarget) must have reduction in short axis to \<10 mm. PR is defined as at least a 30% decrease in the sum of diameters of all target and new measurable lesions.
Time frame: Randomization up to disease progression or relapse, whichever occurs first (up to approximately 5.25 years)
Cohort I, II, III: Overall Survival (OS)
OS was defined as the time from randomization to death from any cause
Time frame: Randomization up to death from any cause (up to approximately 6.5 years)
Cohort I: Percentage of Participants With Confirmed OR (PR or CR), as Determined by the Investigator Using RECIST v1.1
OR was defined as the rate of a PR or CR occurring after randomization and confirmed \>=28 days later as determined by the investigator using RECIST v1.1. As per RECIST v1.1, CR is defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or nontarget) must have reduction in short axis to \<10 mm. PR is defined as at least a 30% decrease in the sum of diameters of all target and new measurable lesions.
Time frame: Randomization up to disease progression or relapse, whichever occurs first (up to approximately 2 years)
Cohort I, II, III: Duration of Response (DOR), as Determined by the Investigator Using RECIST v1.1
DOR was defined as the time from the first occurrence of a documented objective response to the time of relapse, as determined by the investigator using RECIST v1.1 or death from any cause during the study, whichever occurred first.
Time frame: Time from the first occurrence of documented objective response to time of relapse or death, whichever occurs first (up to approximately 6.5 years)
Cohort I, II, III: Percentage of Participants With Unconfirmed Overall Response (OR_uc) (Unconfirmed PR or CR), as Determined by the Investigator Using RECIST v1.1
ORR\_uc (ORR confirmation not required) was defined as the rate of a PR or CR occurring after randomization as determined by the investigator using RECIST v1.1, confirmation not required. As per RECIST v1.1, CR is defined as the disappearance of all target lesions. Any pathological lymph nodes (whether target or nontarget) must have reduction in short axis to \<10 mm. PR is defined as at least a 30% decrease in the sum of diameters of all target and new measurable lesions.
Time frame: Randomization up to disease progression or relapse, whichever occurs fist (up to approximately 6.5 years)
Cohort II, III: Progression-Free Survival, as Determined by Investigator Using RECIST v1.1
PFS was defined as the time from randomization to the first occurrence of disease progression or relapse, as determined by the investigator, using RECIST v1.1. As per RECIST v1.1, PD is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study (nadir), including baseline. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. The appearance of one or more new lesions is also considered progression.
Time frame: Randomization up to disease progression or relapse, whichever occurs first (up to approximately 6.5 years)
Cohort I, II, III: Percentage of Participants With Adverse Events (AEs)
Time frame: Randomization up to end of study (up to approximately 6.5 years)
Cohort I, II, III: Maximum Plasma Concentration (Cmax) of Cobimetinib
Time frame: Safety Run-In: Predose (Hour [Hr] 0) on Cycle (Cy) 1 Day (D) 8; predose (Hr 0), 0.5, 1, 2, 4, 6 Hr postdose (2, 4 Hr postdose for Cohorts II, III) on Cy1 D15; Expansion: predose (Hr 0), 1-4 Hr postdose on Cy1 D15; predose (Hr 0) on Cy2 D15 (Cy=28 days)
Cohort I, II, III: Minimum Plasma Concentration (Cmin) of Cobimetinib
Time frame: Safety Run-In: Predose (Hr 0) on Cy 1 D8; predose (Hr 0), 0.5, 1, 2, 4, 6 Hr postdose (2, 4 Hr postdose for Cohorts II, III) on Cy1 D15; Expansion: predose (Hr 0), 1-4 Hr postdose on Cy1 D15; predose (Hr 0) on Cy2 D15 (Cy=28 days)
Cohort I: Area Under the Concentration-Time Curve From Time Zero to Dosing Interval (AUC0-tau; Total Exposure) of Cobimetinib
Time frame: Safety Run-In: Predose (Hr 0) on Cy 1 D8; predose (Hr 0), 0.5, 1, 2, 4, 6 Hr postdose on Cy1 D15; Expansion: predose (Hr 0), 1-4 Hr postdose on Cy1 D15 (Cy=28 days)
Cohort I, II: Cmax of Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 0.5, 1, 2, 4, and 6 Hr postdose (2, 4 Hr postdose for Cohort II) (infusion duration: 1 Hr) on Cy1 D15 (Cy=28 days)
Cohort I, II: Cmin of Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 0.5, 1, 2, 4, and 6 Hr postdose (2, 4 Hr postdose for Cohort II) (infusion duration: 1 Hr) on Cy1 D15 (Cy=28 days)
Cohort I: AUC0-tau of Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 0.5, 1, 2, 4, and 6 Hr postdose (infusion duration: 1 Hr) on Cy1 D15 (Cy=28 days)
Cohort III: Cmax of Nab-Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 2, 4 Hr postdose (infusion duration: 30 minutes) on Cy1 D15 (Cy=28 days)
Cohort III: Cmin of Nab-Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 2, 4 Hr postdose (infusion duration: 30 minutes) on Cy1 D15 (Cy=28 days)
Cohort III: AUC0-tau of Nab-Paclitaxel
Time frame: Safety Run-In: Predose (Hr 0) on Cy1 D8; predose (Hr 0), 2, 4 Hr postdose (infusion duration: 30 minutes) on Cy1 D15 (Cy=28 days)
Cohort II, III: Cmax (in Serum) of Atezolizumab
Time frame: Safety Run-In, Expansion:Predose (Hr0), 0.5Hr postdose (infusion duration:1Hr) on D1 of Cy1, 3; predose (Hr0) on D1 of Cy2, 4, 8, every 8 Cy up to end of treatment (EOT); 120 days after EOT (approximately 5.25 years) (Cy=28 days)
Cohort II, III: Cmin (in Serum) of Atezolizumab
Time frame: Safety Run-In, Expansion: Predose (Hr 0), 0.5 Hr postdose (infusion duration: 1 Hr) on D1 of Cy1, 3; predose (Hr 0) on D1 of Cy2, 4, 8, every 8 Cy up to EOT; 120 days after EOT (approximately 5.5 years) (Cy=28 days)
Cohort II, III: AUC0-tau (in Serum) of Atezolizumab
Time frame: Safety Run-In, Expansion: Predose (Hr 0), 0.5 Hr postdose (infusion duration: 1 Hr) on D1 of Cy1, 3; predose (Hr 0) on D1 of Cy2, 4, 8, every 8 Cy up to EOT (approximately 5.5 years); 120 days after EOT (approximately 5.5 years) (Cy=28 days)
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