Cyclin dEpendent Kinase in tRiple nEGatIVe brEast canceR - a "Window of Opportunity" Study

Inclusion Criteria: * females or males \>18 years old at the time of informed consent signature; * diagnosis of potentially resectable or de novo metastatic (stage II-IV) invasive carcinoma of the breast; * eligible for standard neoadjuvant or palliative paclitaxel and/or carboplatin-based chemotherapy as determined by Investigator; * triple negative tumor defined as: * hormone receptor-negative (\<1% ER/PgR expression); * HER2-negative (Immunohistochemistry (IHC) score ≤1 or IHC score =2 and negative for the amplification by in situ hybridization); * multicentric/multifocal disease is allowed, provided that all lesions have been biopsied and their phenotype has been confirmed pathologically as TNBC; * no previous anticancer therapy for this malignancy; * clinically or radiographically measurable disease (discrete lesion only, enhancement is not included) within the breast, that can be biopsied, defined as longest diameter \>2 cm; * multicentric or multifocal disease is allowed if at least 1 lesion is \>2 cm; * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; * adequate bone marrow and organ function as defined by the following local laboratory values: * hemoglobin ≥9 g/dL; * absolute neutrophil count (ANC) ≥1500/μL; * platelets ≥100,000/μL; * total bilirubin ≤ institutional upper limit of normal (ULN), unless diagnosis of Gilbert syndrome; * aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5x ULN; * creatinine ≤ ULN OR creatinine clearance ≥50 mL/min per Cockcroft-Gault equation for patients with creatinine levels greater than ULN. * blood glucose level \<120 mg/dL after at least 6 hours of fasting; * standard 12-lead electrocardiogram (ECG) without clinically significant abnormalities; * ability to undergo contrast-enhanced MRI; * ability to swallow and retain oral medication; * all study participants of child-bearing potential must agree to use adequate contraceptive methods prior to study entry, during the study and for the following 3 weeks (females) or 14 weeks (males); * prior chemotherapy, other targeted anticancer therapies, or prior radiation therapy (outside of treated breast) for other malignancy treated with radical intent is allowed, provided the treatment was completed ≥1 year before informed consent signature; * prior bisphosphonate therapy is allowed; * willing and able to undergo all the procedures required by the study protocol; * provision of written informed consent form prior to receiving any study related procedure. Exclusion Criteria: * inflammatory breast cancer; * prior systemic treatment for this malignancy; * prior treatment with CDK4/6 inhibitor; * known hypersensitivity to study medications or any of their excipients; * major surgery or radiotherapy (apart from limited field radiotherapy for symptom control) within 14 days prior to randomization; * concurrent invasive malignancy; * known HIV, active HBV or HCV infection; * active autoimmune disease requiring ongoing immunosuppressive therapy; * history of allotransplantation; * concurrent treatment with systemic immunosuppressive agents, including steroids, within 3 weeks of enrolment; * presence of implants or devices not compatible with MRI; * pregnant or nursing female participants; * receiving strong inhibitors or inducers of CYP3A4/5 or medications with narrow therapeutic window that are predominantly metabolized through CYP3A4/5; * impairment of GI function that may significantly alter the absorption of the oral trial treatments; * unwilling or unable to follow protocol requirements, including obligatory biopsies; * any condition which in the Investigator's opinion deems the participant an unsuitable candidate to receive study drugs; * any other concurrent severe and/or uncontrolled medical condition that would, in the Investigator's judgment, contraindicate patient participation in the clinical trial or compromise compliance with the protocol.