A phase II randomized trial of cobimetinib plus chemotherapy, with or without atezolizumab, as first-line treatment for patients with locally advanced or metastatic triple-negative breast cancer (COLET): primary analysis
Bibliographic record
Abstract
•Cobimetinib plus paclitaxel trended toward a numerical increase in progression-free survival and objective response rate.•The triplet combination of atezolizumab, cobimetinib, and taxane did not appear to increase objective response rate.•The triplet combination showed a trend toward improved objective response rate in patients with programmed death-ligand 1 (PD-L1)-positive disease.•These results demonstrate the potential activity of combination immunotherapy for this difficult-to-treat patient subgroup. BackgroundResistance to standard chemotherapy in metastatic triple-negative breast cancer (mTNBC) is associated with upregulation of the mitogen-activated protein kinase (MAPK) pathway. Cobimetinib, an MAPK/extracellular signal-regulated kinase (MEK) inhibitor, may increase sensitivity to taxanes and programmed death-ligand 1 inhibitors. COLET is a three-cohort phase II study evaluating first-line cobimetinib plus chemotherapy, with or without atezolizumab, in patients with locally advanced or mTNBC.Patients and methodsPatients were ≥18 years with locally advanced or mTNBC. Following a safety run-in, patients in cohort I were randomized 1:1 to cobimetinib (60 mg, D3-D23 of each 28-day cycle) or placebo, plus paclitaxel (80 mg/m2, D1, 8, and 15). Additional patients were randomized (1:1) to cohort II or III to receive cobimetinib plus atezolizumab (840 mg, D1 and D15) and either paclitaxel (cohort II) or nab-paclitaxel [cohort III (100 mg/m2, D1, D8, and D15)]. Primary endpoints were investigator-assessed progression-free survival (PFS) (cohort I) and confirmed objective response rate (ORR) (cohorts II/III). Safety and tolerability were also assessed.ResultsIn the expansion stages, median PFS was 5.5 months for cobimetinib/paclitaxel versus 3.8 months for placebo/paclitaxel in cohort I [hazard ratio 0.73; 95% confidence interval (CI) 0.43-1.24; P = 0.25]. In cohort I, ORR was 38.3% (95% CI 24.40-52.20) for cobimetinib/paclitaxel and 20.9% (95% CI 8.77-33.09) for placebo/paclitaxel; ORRs in cohorts II and III were 34.4% (95% CI 18.57-53.19) and 29.0% (95% CI 14.22-48.04), respectively. Diarrhea was the most common grade ≥3 adverse events across all cohorts.ConclusionsCobimetinib added to paclitaxel did not lead to a statistically significant increase in PFS or ORR, although a nonsignificant trend toward a numerical increase was observed. Cobimetinib plus atezolizumab and a taxane did not appear to increase ORR. This demonstrates the potential activity of a combinatorial MEK inhibitor, chemotherapy, and immunotherapy in this difficult-to-treat population. Resistance to standard chemotherapy in metastatic triple-negative breast cancer (mTNBC) is associated with upregulation of the mitogen-activated protein kinase (MAPK) pathway. Cobimetinib, an MAPK/extracellular signal-regulated kinase (MEK) inhibitor, may increase sensitivity to taxanes and programmed death-ligand 1 inhibitors. COLET is a three-cohort phase II study evaluating first-line cobimetinib plus chemotherapy, with or without atezolizumab, in patients with locally advanced or mTNBC. Patients were ≥18 years with locally advanced or mTNBC. Following a safety run-in, patients in cohort I were randomized 1:1 to cobimetinib (60 mg, D3-D23 of each 28-day cycle) or placebo, plus paclitaxel (80 mg/m2, D1, 8, and 15). Additional patients were randomized (1:1) to cohort II or III to receive cobimetinib plus atezolizumab (840 mg, D1 and D15) and either paclitaxel (cohort II) or nab-paclitaxel [cohort III (100 mg/m2, D1, D8, and D15)]. Primary endpoints were investigator-assessed progression-free survival (PFS) (cohort I) and confirmed objective response rate (ORR) (cohorts II/III). Safety and tolerability were also assessed. In the expansion stages, median PFS was 5.5 months for cobimetinib/paclitaxel versus 3.8 months for placebo/paclitaxel in cohort I [hazard ratio 0.73; 95% confidence interval (CI) 0.43-1.24; P = 0.25]. In cohort I, ORR was 38.3% (95% CI 24.40-52.20) for cobimetinib/paclitaxel and 20.9% (95% CI 8.77-33.09) for placebo/paclitaxel; ORRs in cohorts II and III were 34.4% (95% CI 18.57-53.19) and 29.0% (95% CI 14.22-48.04), respectively. Diarrhea was the most common grade ≥3 adverse events across all cohorts. Cobimetinib added to paclitaxel did not lead to a statistically significant increase in PFS or ORR, although a nonsignificant trend toward a numerical increase was observed. Cobimetinib plus atezolizumab and a taxane did not appear to increase ORR. This demonstrates the potential activity of a combinatorial MEK inhibitor, chemotherapy, and immunotherapy in this difficult-to-treat population.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".