CADTH reimbursement reviews are comprehensive assessments of the clinical effectiveness and cost-effectiveness, as well as patient and clinician perspectives, of a drug or drug class. The assessments inform non-binding recommendations that help guide the reimbursement decisions of Canada's federal, provincial, and territorial governments, with the exception of Quebec. This review assesses pembrolizumab (Keytruda), 200 mg IV every 3 weeks or 400 mg IV every 6 weeks. Indication: For the treatment of adult patients with high-risk, early-stage triple-negative breast cancer in combination with chemotherapy as neoadjuvant treatment and then continued as monotherapy as adjuvant treatment after surgery.