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PALLAS (BIG 14-03) identifier: NCT02513394



PALbociclib CoLlaborative Adjuvant Study: A randomized phase III trial of Palbociclib with standard adjuvant endocrine therapy versus standard adjuvant endocrine therapy alone for hormone receptor positive (HR+) / human epidermal growth factor receptor 2 (HER2)-negative early breast cancer


PALLAS will assess if adding a drug called palbociclib, when combined with standard endocrine treatment for a subtype of early-stage breast cancer called “luminal,” improves the outcome of patients with the disease. It will also assess the safety profile of this combination and try to identify specific molecular markers to predict which patients will benefit most from this treatment combination.

Palbociclib is a drug that may stop cancer cells from growing. It blocks the activity of two closely related enzymes (proteins that help chemical reactions occur in the body), called cyclin D kinases 4 and 6 (CDK 4/6). These proteins are part of a pathway, or a sequence of steps, which is known to regulate cell growth. Laboratory testing has suggested that palbociclib may stop the growth of breast cancer cells of the luminal subtype.

Endocrine therapy in this study will consist of either tamoxifen or aromatase inhibitors (anastrozole, letrozole, exemestane), both being well-established endocrine therapy options used for patients with early stage breast cancer.


The standard treatment for the luminal subtype of breast cancer is endocrine therapy: this is a therapy that prevents breast cancer cell growth by blocking oestrogen stimulation. Despite its success, some patients still develop recurrence of their disease. Clinical studies in late stage (metastatic) breast cancer have shown that combining palbociclib with endocrine therapy provides better control. PALLAS will evaluate this approach for patients with early-stage disease.

The main objective of PALLAS is to compare the clinical benefits and the effects of giving 2 years of palbociclib in combination with standard endocrine therapy, versus standard endocrine therapy alone.


Patients enrolled in PALLAS will be randomly assigned to two different groups. After the surgical procedure to remove the primary breast tumour, patients will receive either:

- palbociclib for 2 years in combination with standard endocrine treatment for at least 5 years.

- standard endocrine treatment for at least 5 years.



Approximately 4600 patients who have the luminal subtype of early breast cancer (hormone receptor positive ([HR+]/ human epidermal growth factor receptor 2 [HER2]-negative early breast cancer).


Research Groups

This study is conducted and sponsored by the Alliance Foundation Trials, LLC (AFT), and Austrian Breast & Colorectal Cancer Study Group (ABCSG), in collaboration with the Breast International Group (BIG). 


The recruitment opened in October 2015 and is currently ongoing.


170 hospitals in the U.S. and approximately 235 hospitals in Europe, Canada, Australia, Japan, South Korea, and Israel are participating.


Not yet applicable.


A grant from Pfizer.


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