LORELEI is an international, two-arm, randomised, double-blind, pre-operative study for postmenopausal women with oestrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER +/HER2 -) early stage, untreated, Stage I-III operable breast cancer whose primary tumours are 2 cm or bigger.

In ER+ breast cancer, patients can become resistant to endocrine treatments like letrozole, and this appears to be related to the activation of the PI3K pathway. Therefore, it is hypothesised that combining letrozole with the PI3K blocking drug GDC-0032 could be more effective than letrozole alone.

The purpose of LORELEI is to determine if combining GDC-0032 with letrozole in treatment of patients with previously untreated, postmenopausal ER+, HER-, stage I-III breast cancer is better than giving letrozole alone. Both the response of tumours to the treatment and safety will be carefully evaluated.

The study is being conducted under the Breast International Group (BIG) umbrella as a collaboration between the Austrian Breast & Colorectal Cancer Study Group (ABCSG), SOLTI, BIG Headquarters, and Genentech. Joining ABCSG and SOLTI to recruit patients were 6 additional BIG groups, in total covering 22 countries:  ANZBCTG, EORTC, IBCSG, GOIRC, GECOPERU and LACOG.

Find out more about LORELEI by reading our Study Factsheet

Coordinating academic partners:

https://www.abcsg.com/
http://www.gruposolti.org/en
http://www.bigagainstbc.org