A Clinical Study of Boserolimab (MK-5890) With Pembrolizumab and Chemotherapy in People With Early Triple-Negative Breast Cancer (MK-5890-003)

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

* Has previously untreated high-risk, early-stage, non-metastatic (M0) breast cancer (BC), defined as tumor stage T1c, nodal stage N1-2, or tumor stage T2-4, nodal stage N0-2
* Has provided a core needle biopsy for tissue diagnosis of the current breast cancer less than 29 days prior to the date of informed consent
* Has centrally confirmed diagnosis of BC that is triple-negative based on the American Society of Clinical Oncology/College of American Pathologists guidelines
* Has Eastern Cooperative Oncology Group performance status of 0 or 1 performed within 28 days before treatment randomization
* Has left ventricle ejection fraction of ≥50% as assessed by echocardiogram or multigated acquisition scan performed at screening
* Has a history of exposure to anthracycline; participants can be eligible after completion of a Sponsor consultation form, if cumulative lifetime doses are as follows: Doxorubicin \<100 mg/m2, Epirubicin \<180 mg/m2, Mitoxantrone \<40 mg/m2, Idarubicin \<22.5 mg/m2. Note: If another anthracycline or more than one anthracycline has been used, the cumulative dose must not exceed the equivalent of 100 mg/m2 of doxorubicin

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

* Has documented Grade ≥2 peripheral neuropathy
* Has uncontrolled or significant cardiovascular disease
* Has received prior therapy with an anti-programmed cell death protein 1 (anti-PD-1), anti-programmed cell death-ligand 1 (anti-PD-L1), or anti-PD-L2 agent, or with an agent directed to another stimulatory or coinhibitory T-cell receptor (e.g., cytotoxic T-lymphocyte-associated protein-4 \[CTLA-4\], OX-40 \[cluster of differentiation (CD) 134\], or CD137)
* Has received any prior treatment, including radiation, systemic therapy, and/or definitive surgery for currently diagnosed breast cancer
* Has received prior systemic anticancer therapy
* Has undergone excisional biopsy of the primary tumor and/or axillary lymph node dissection prior to study treatment
* Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of study intervention
* Has a known additional malignancy that is progressing or has required active treatment within the past 5 years
* Has active autoimmune disease that has required systemic treatment in the past 2 years with need for disease modifying agents such as corticosteroids or immunosuppressive drugs
* Has history of (noninfectious) pneumonitis/interstitial lung disease that required steroids or has current pneumonitis/interstitial lung disease
* Has an active infection requiring systemic therapy
* HIV-infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease
* Has severe hypersensitivity (Grade ≥3) to pembrolizumab, any investigational agent or study intervention, any of its excipients, and/or to another biologic therapy
* Has a history of allogeneic tissue/solid organ transplant