A Brufsky1, S B Kim2, Ž Zvirbule3, A Eniu4, J Mebis5, J H Sohn6, M Wongchenko7, S Chohan8, R Amin7, Y Yan7, V McNally9, D Miles10, S Loi11. 1. Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA. Electronic address: brufskyam@upmc.edu. 2. Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea. 3. Department of Oncology, Latvian Oncology Centre of Riga East Clinical University Hospital, Riga, Latvia. 4. Department of Breast Tumors, Cancer Institute 'Prof. Dr. Ion Chiricuţă' (IOCN), Cluj-Napoca, Romania. 5. Department of Medical Oncology, Jessa Ziekenhuis, University of Hasselt, Belgium. 6. Department of Internal Medicine, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea. 7. Genentech, Inc., South San Francisco, USA. 8. F. Hoffmann-La Roche, Ltd., Mississauga, Canada. 9. Roche Products Ltd, Welwyn Garden City, UK. 10. Mount Vernon Cancer Centre, Northwood, UK. 11. Division of Clinical Medicine and Research, Peter MacCallum Cancer Centre, University of Melbourne, Melbourne, Australia. Electronic address: sherene.loi@petermac.org.
Abstract
BACKGROUND: 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 AND METHODS: 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. RESULTS: 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. CONCLUSIONS: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.
RCT Entities:
BACKGROUND: 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 AND METHODS: 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. RESULTS: 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. CONCLUSIONS: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.
Authors: Lars Hanker; Frank Köster; Karen Bräutigam; Elodie Kabore-Wolff; Ahmad Fawzi Hussain; Stephan Polack; Achim Rody Journal: J Cancer Res Clin Oncol Date: 2021-06-29 Impact factor: 4.553