About the Authors

Sherene Loi

sherene.loi@bordet.be

Affiliation Breast Cancer Translational Research Laboratory (BCTL), Jules Bordet Institute, Brussels, Belgium

Stefan Michiels

Affiliation Breast Cancer Translational Research Laboratory (BCTL), Jules Bordet Institute, Brussels, Belgium

Jose Baselga

Affiliation Division of Hematology and Oncology, Massachusetts General Hospital Cancer Center, Boston, Massachusetts, United States of America

John M. S. Bartlett

Affiliations Endocrine Cancer Group, University of Edinburgh Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom, Ontario Institute for Cancer Research, Toronto, Ontario, Canada

Sandeep K. Singhal

Affiliation Breast Cancer Translational Research Laboratory (BCTL), Jules Bordet Institute, Brussels, Belgium

Vicky S. Sabine

Affiliation Endocrine Cancer Group, University of Edinburgh Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom

Andrew H. Sims

Affiliation Edinburgh Breast Unit, Institute of Genetics & Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom

Tarek Sahmoud

Affiliation Novartis Pharma, East Hanover, New Jersey, United States of America

J. Michael Dixon

Affiliation Applied Bioinformatics of Cancer Group, Edinburgh Breakthrough Unit, University of Edinburgh Cancer Research Centre, Institute of Genetics & Molecular Medicine, Western General Hospital, Edinburgh, United Kingdom

Martine J. Piccart

Affiliation Department of Medicine, Jules Bordet Institute, Brussels, Belgium

Christos Sotiriou

Affiliation Breast Cancer Translational Research Laboratory (BCTL), Jules Bordet Institute, Brussels, Belgium

Competing Interests

SL and CS are named inventors on a provisional worldwide patent filed by the Université Libre de Bruxelles for the PIK3CA mutation-associated gene signature (PIK3CA-GS). TS is an employee of Novartis Pharma. All the other authors declare no conflicts of interest. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: SL SM JMSB CS. Performed the experiments: SL SM. Analyzed the data: SL SM. Contributed reagents/materials/analysis tools: JB JMSB SKS VSS AHS TS JMD MJP CS. Wrote the paper: SL SM.