Circadian Rhythm Impact on Triple Negative Breast Cancer Response to Neoadjuvant Immunotherapy - a Feasibility Randomized Trial

Patients will be randomized 1:1 to receive all neoadjuvant pembrolizumab cycles (400 mg every 6 weeks) before versus after noon. Subjects will be stratified based on clinical stage at diagnosis (St. II vs III).

Primary outcome will be pCR rate. As a secondary outcome, we will assess for treatment related toxicity.

For planned exploratory circadian rhythm evaluation, daily body temperature and salivary cortisol variation will be measured before each ICI infusion and the Munich Chronotype Questionnaire (MCTQ) will be applied. To assess for emotional stress, physical exercise habits, stimulating substances use and light exposure, patients will also be subjected to the Distress Thermometer and a lifestyle questionnaire. For planned exploratory biomarker research, tumor infiltrating lymphocytes (TILs) analysis will be performed on the initial diagnostic biopsy and after surgery, on residual tumor (in patients not achieving pCR). Cytokine quantification and bulk RNA sequencing plus flow cytometry studies for immune populations profiling will be performed on peripheral blood, at baseline and before surgery, to check for potential biomarkers of circadian modulation.