A Trial of Early Detection of Molecular Relapse With Circulating Tumour DNA Tracking and Treatment With Palbociclib Plus Fulvestrant Versus Standard Endocrine Therapy in Patients With ER Positive HER2 Negative Breast Cancer

Detection of molecular relapse with circulating tumour DNA analysis can identify which patients with ER positive breast cancer are relapsing on adjuvant endocrine therapy. This trial will aim to demonstrate that palbociclib and fulvestrant, can defer or prevent relapse in patients with ctDNA detected molecular relapse. The TRAK-ER trial will have two phases, a ctDNA surveillance phase and a randomised therapy trial in patients with positive ctDNA. The TRAK-ER trial will establish a ctDNA screening programme for patients with ER positive breast cancer receiving adjuvant endocrine therapy with at least a further three years of standard adjuvant endocrine therapy planned. Patients recruited into the TRAK-ER study will have high-risk clinical features to identify patients at higher risk of future relapse. ctDNA assays will be used to identify which people are at very high risk of relapse (i.e. those with a positive ctDNA result), and randomise this high risk population between standard endocrine therapy versus palbociclib plus fulvestrant for up to two years.