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Loibl S, de la Pena L, Nekljudova V, Zardavas D, Michiels S, Denkert C, Rezai M, Bermejo B, Untch M, Lee SC, Turri S, Urban P, Kümmel S, Steger G, Gombos A, Lux M, Piccart MJ, Von Minckwitz G, Baselga J, Loi S. Neoadjuvant buparlisib plus trastuzumab and paclitaxel for women with HER2+ primary breast cancer: A randomised, double-blind, placebo-controlled phase II trial (NeoPHOEBE). Eur J Cancer 2017; 85:133-145. [PMID: 28923573 PMCID: PMC5640494 DOI: 10.1016/j.ejca.2017.08.020] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/18/2017] [Accepted: 08/18/2017] [Indexed: 12/25/2022]
Abstract
AIM The Neoadjuvant PI3K inhibition in HER2 OverExpressing Breast cancEr (NeoPHOEBE) trial evaluated the efficacy and safety of buparlisib, a pan-phosphatidylinositol 3-kinase (PI3K) inhibitor, plus trastuzumab and paclitaxel as neoadjuvant treatment for human epidermal growth factor receptor-2 positive (HER2+) breast cancer. METHODS NeoPHOEBE was a neoadjuvant, phase II, randomised, double-blind study. Women with HER2+ breast cancer were randomised within two independent cohorts by PIK3CA mutation status and, in each cohort stratified by oestrogen receptor (ER) status to receive buparlisib or placebo plus trastuzumab (first 6 weeks) followed by buparlisib or placebo with trastuzumab and paclitaxel. Primary end-point was pathological complete response (pCR) rate; key secondary end-point was objective response rate (ORR) at 6 weeks. Exploratory end-points were evaluation of Ki67 levels and change in tumour infiltrating lymphocytes (TILs) in intermediate biopsies at day 15. RESULTS Recruitment was suspended mainly due to liver toxicity after enrolment of 50 of the planned 256 patients. In each arm (buparlisib n = 25; placebo n = 25) 21 patients (84%) had wild type PIK3CA and 4 patients (16%) had mutant PIK3CA. Overall, pCR rate was similar between buparlisib and placebo arms (32.0% versus 40%; one-sided P = 0.811). A trend towards higher ORR (68.8% versus 33.3%; P = 0.053) and a significant decrease in Ki67 (75% versus 26.7%; P = 0.021) was observed in buparlisib versus placebo arm in the ER+ subgroup (Pinteraction = 0.03). CONCLUSIONS Addition of the pan-PI3K inhibitor buparlisib to taxane-trastuzumab-based therapy in HER2+ early breast cancer was not feasible. However, the higher ORR and Ki67 reduction in the ER+, HER2+ subgroup indicates a potential role for PI3K-targeted therapy in this setting and may warrant further investigation with better-tolerated second-generation PI3K inhibitors. TRIAL REGISTRATION IDENTIFIER NCT01816594.
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Affiliation(s)
- Sibylle Loibl
- German Breast Group, Neu-Isenburg, Germany; Sana-Klinikum Offenbach, Germany.
| | | | | | | | - Stefan Michiels
- Gustave Roussy, Service de Biostatistique et d'Epidémiologie, Villejuif, France; CESP, Inserm U1018, Univ. Paris Sud, Univ. Paris-Saclay, Villejuif, France
| | - Carsten Denkert
- Institute of Pathology, Charité University Hospital, Berlin, Germany
| | | | | | - Michael Untch
- Helios Klinikum Berlin-Buch, Department of Obstetrics and Gynaecology, Berlin, Germany
| | - Soo Chin Lee
- Department of Haematology-Oncology, National University Cancer Institute, Singapore
| | | | | | | | - Guenther Steger
- Department of Internal Medicine I, Division of Oncology, Medical University of Vienna, Austria; Comprehensive Cancer Center Vienna, Austria
| | - Andrea Gombos
- Université Libre de Bruxelles, Institut Jules Rue Héger-Bordet 1, Medical Oncology Clinic, Belgium
| | - Michael Lux
- University Breast Centre of Franconia, OBGYN Department, University Hospital Erlangen, CCC Erlangen-EMN, Germany
| | - Martine J Piccart
- Breast International Group, Brussels, Belgium; Université Libre de Bruxelles, Institut Jules Rue Héger-Bordet 1, Medical Oncology Clinic, Belgium
| | | | - José Baselga
- SOLTI Breast Cancer Research Group, Barcelona, Spain; Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Sherene Loi
- Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Australian New Zealand Breast Cancer Trials Group (ANZBCTG), Newcastle, Australia.
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