Overcoming endocrine resistance in metastatic breast cancer: Current evidence and future directions

Table 1 Ongoing clinical trials of PI3K inhibitors in combination with endocrine therapy in hormone receptor-positive metastatic breast cancer

Treatment	Disease conditions	Trial status	Trial number
Phase I
BYL719 + letrozole	Postmenopausal women hormone receptor-positive stage IV breast cancer	Ongoing	NCT01791478
BKM120 + fulvestrant	Postmenopausal women estrogen receptor-positive stage IV breast cancer	Ongoing	NCT01339442
BKM120 or BEZ235 + letrozole	Postmenopausal women hormone receptor-positive stage IV breast cancer	Ongoing, not recruiting	NCT01248494
XL147 or XL765 + letrozole	Postmenopausal women hormone receptor-positive stage IV breast cancer	Completed	NCT01082068
Phase II
PF-04691502 + exemestane vs exemestane alone	Estrogen receptor-positive stage IV breast cancer	Withdrawn prior to enrolment	NCT01658176
PF-4691502 + letrozole vs letrozole alone	Postmenopausal women estrogen receptor-positive early (phase II) and advanced (phase Ib) breast cancer	Terminated	NCT01430585
GDC-0941 or GDC-0980/placebo + fulvestrant	Postmenopausal women estrogen receptor-positive, AI treated, stage IIIB-IV breast cancer	Ongoing	NCT01437566
Phase III
BKM120/placebo + fulvestrant	Postmenopausal women hormone receptor-positive, AI treated, stage IIIB-IV breast cancer progressed on or after mTOR inhibitor-based treatment	Ongoing	NCT01633060
BKM120/placebo + fulvestrant	Postmenopausal women hormone receptor-positive, stage IIIB-IV breast cancer refractory to AIs	Ongoing	NCT01610284