The response to neoadjuvant chemotherapy (NAC) in early stage breast cancer has important prognostic implications. Early, dynamic prediction of response allows for adaption of the treatment plan before completion, or even before the start of treatment. This strategy can help prevent overtreatment and related toxicity and correct for undertreatment with an ineffective regimen. The hypothesis of this study is that accurate dynamic response prediction may be reached by combining multi-parametric MRI with liquid biopsies prior to, during and after NAC, in addition to conventional clinical and pathological information. Magnetic resonance imaging (MRI) is non-invasive and is typically used for response evaluation in current clinical practice. It shows the size and perfusion of the tumor as they change during treatment. However, tumor size on MRI has limited predictive value for response to therapy. Multi-parametric MRI uses different imaging protocols in one session to measure more functional items than perfusion alone, addressing different aspects of tumor biology, and possibly improving predictive value. With this improvement, imaging still only visualizes macroscopic disease. Therefore, in the LIMA study, MRI will be combined with liquid biopsies containing circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), which have both shown prognostic and predictive values in early stage breast cancer. Since the ctDNA may originate from cells in every part of the tumor, it may capture tumor heterogeneity. Liquid biopsies are minimally invasive and provide insight into microscopic tumor load and the tumor's genetic picture.

The aim of the study is to show proof of concept for combining multi-parametric MRI with liquid biopsies in addition to conventional clinical and pathologic information, to accurately predict response to neoadjuvant treatment for patients with primary breast cancer.

The LIMA is a multicenter prospective observational cohort study. Multi-parametric MRI will we performed prior to NAC, halfway and after completion of NAC. Liquid biopsies will be obtained before start of treatment, every 2 weeks during treatment and after completion of NAC. 100 patients will be enrolled in different hospitals.

Funding from the European Union Horizon 2020 research and innovation program under grant agreement no. 755333 (LIMA)