Inclusion Criteria:

1. Subjects will be between the ages of 15 and 75, inclusive. 2. Subjects must have a histologically confirmed diagnosis of a solid tumor metastatic to bone, or a histologically confirmed diagnosis of a solid tumor to the bone or metastatic to the bone. 3. Subjects must have measurable disease on anatomic imaging that is also avid for phosphonate compounds as demonstrated by a positive 99mTc diphosphonate bone scan. Not all lesions must be positive on bone scan. 4. Adequate organ function, including: i. Adequate renal function, defined as a measured creatinine clearance >70 mL/min/1.73 m2 or normal radioisotope glomerular filtration rate (GFR). ii. Adequate hematologic function, defined as a platelet count >100,000 cells/mm3 and an absolute neutrophil count (ANC) >1,000 cells/mm3. 5. Life expectancy of at least eight weeks. 6. Karnofsky performance status >50%. 7. Subjects must have adequately recovered from the effects of any prior chemotherapy, as determined by the treating physician and study team, based in part on organ function defined above. Toxicities from previous therapies must have recovered to CTCAE v5.0 grade ≤1. Subjects with Grade 2 anemia per CTCAE v5.0 will be permitted as long as the subject has normal cardiac function. 8. Adequate cardiac function. Subjects with previously identified cardiac disease will be eligible, as 153Sm-DOTMP is not expected to cause cardiac dysfunction and is only expected to result in very transient hypocalcemia. 9. A stem cell product collected either by peripheral stem cell mobilization or bone marrow harvest prior to the infusion of CycloSam® must be available, prior to trial entry. A minimum of 2 x 106 CD34+ cells/kg ideal body weight are required. 10. Female subjects of child-bearing potential (defined as premenopausal and capable of becoming pregnant) must have a negative serum pregnancy test at the Screening visit. Females must be surgically sterile, postmenopausal for at least one year prior to Screening (no other medical cause involved) with a Follicle Stimulating Hormone (FSH) level of greater than 40 mIU/mL or must be using a highly effective method of birth control and agree to its use for at least 30 days following the last dose of 153Sm-DOTMP. Highly effective methods of contraceptive are defined as tubal ligation or an approved hormonal contraceptive such as oral contraceptives, patches, implants, injections, rings, or hormonally-impregnated intrauterine device. 11. Male subjects with partners of child-bearing potential must agree to use highly effective methods of contraception for at least 90 days after the last dose of 153Sm-DOTMP. 12. The subject and/or the subject's legally authorized guardian, if the subject is a minor, must acknowledge in writing that informed consent to become a study subject has been obtained, in accordance with institutional policies approved by the U.S. Department of Health and Human Services. 13. Subjects must have previously received effective treatment for their underlying disease and have no potentially curative options available. 14. The concurrent use of hormonal therapies or bisphosphonates is acceptable, provided the latter do not render target lesions invisible on 99mTc bone scan. Subjects will have the option to re-screen up to once more after seven days if they do not initially meet all of the inclusion criteria

Exclusion Criteria:

1. Subject is pregnant or breastfeeding. 2. Subject is sexually active and does not agree to use accepted, effective forms of contraceptive. 3. Subject has received prior radiotherapy to all known areas of current active disease. 4. Subject has a body mass index (BMI) > 50 kg/m2.

Inclusion Criteria:

• HER2-positive status will be based on pretreatment biopsy material and defined as an immunohistochemistry (IHC) score of 3+ and/or positive by in situ hybridization (ISH) according to current American Society of Clinical Oncology (ASCO) College of American Pathologists (CAP) guidelines. Central testing is not required * Known hormone receptor (HR) status as defined by ASCO/CAP guidelines (based on pretreatment biopsy material). Hormone receptor positive status can be determined by either known positive estrogen receptor (ER) or known positive progesterone receptor (PR) status; hormone receptor negative status must be determined by both known negative ER and known negative PR
• Patients with clinical stage T1-4, N0-3 disease at presentation and residual invasive disease postoperatively as defined above are eligible. (Note: Patients with T1a/bN0 tumors are not eligible at initial breast cancer diagnosis are not eligible)
• Patients with residual HR-negative, HER2 positive (+) disease in the breast and/or lymph nodes per the surgical pathology report are eligible; however, patients with HR+ HER2+ cancers must have node-positive residual disease per the surgical pathology report in order to qualify for the study. The presence of residual invasive disease in the breast is not mandatory for these patients
• Patients with weakly ER-positive (1-10%) breast cancer (based on the pretreatment core biopsy) are eligible even if they have node-negative disease per the surgical pathology report
• The residual disease tissue (breast and/or lymph nodes) is not required to be HER2-positive, as eligibility for NCI-2020-03770 (A011801) is based on a positive HER2 status at the time of the initial breast cancer diagnosis * Note: The presence of micrometastases in lymph nodes after preoperative therapy counts as residual disease, whereas the presence of isolated tumor cells does not
• Patients with synchronous bilateral invasive disease are eligible provided both lesions were confirmed to be HER2-positive, and at least one of the lesions meets the criteria outlined above. Multifocal disease is allowed, as long as the largest biopsied breast tumor was HER2-positive
• Patients must have received neoadjuvant chemotherapy with one of the following regimens: docetaxel/trastuzumab/pertuzumab (THP), paclitaxel/methotrexate/cisplatin (TMP), doxorubicin/cyclophosphamide/paclitaxel/trastuzumab/pertuzumab (AC-TH(P)); docetaxel/carboplatin/trastuzumab/pertuzumab (TCH(P)); fluorouracil/doxorubicin/cyclophosphamide-docetaxel/trastuzumab/pertuzumab (FAC-TH(P)), or fluorouracil/epirubicin/cyclophosphamide-docetaxel/trastuzumab/pertuzumab (FEC-TH(P)). Note: apart from TCHP, where T is docetaxel, treatment with docetaxel or paclitaxel is acceptable
• Prior receipt of T-DM1 in the neoadjuvant setting is not allowed.
• Prior treatment must have consisted of >= 6 cycles of chemotherapy and HER2-directed therapy, with a total duration of >= 12 weeks, including at least 9 weeks of preoperative taxane and trastuzumab with or without pertuzumab (or Food and Drug Administration [FDA]-approved biosimilars). Patients who have received at least 9 weeks of preoperative taxane, pertuzumab and margetuximab are also eligible if they received >= 6 cycles of systemic therapy prior to enrollment. Note: Patients who complete at least nine of a planned twelve doses of weekly paclitaxel, or three of a planned four doses of docetaxel, but discontinue prematurely due to toxicity are eligible. Patients receiving dose-dense chemotherapy regimens are also eligible. Prior use of nab-paclitaxel (Abraxane) instead of paclitaxel or docetaxel is permitted. Prior use of subcutaneous trastuzumab (Hylecta) and subcutaneous trastuzumab and pertuzumab (Phesgo) is also allowed.
• Patients who received neoadjuvant systemic therapy which included experimental HER2-targeted therapy/therapies are potentially eligible, as long as the investigational agent was not a HER2-targeted antibody-drug conjugate (e.g. T-DM1, DS-8201a [trastuzumab deruxtecan]) or a HER2 targeted tyrosine kinase inhibitor (TKI) (e.g. tucatinib, lapatinib, neratinib).
• Patients may have received =< 1 cycles of T-DM1 in the adjuvant setting. Note: These patients will be randomized to receive a further 14 cycles of T-DM1 and tucatinib/placebo as tolerated. The most recent cycle of T-DM1 should have been administered =< 5 weeks prior to registration * Note: Both of the following two criteria need to be met for the patient to be eligible for this study
• An interval of no more than 12 weeks between the completion date of the last definitive treatment (e.g. postoperative chemotherapy or radiation, or if neither given, breast surgical date) and the date of registration. Concurrent radiation therapy is permitted while receiving study treatment
• Patients must be registered on study within =< 180 days of the date of the most recent definitive breast cancer surgery (not including reconstructive surgery)
• All systemic chemotherapy should have been completed preoperatively unless participating in EA1181 (CompassHER2 pathologic complete response [pCR]) or the BIG DECRESCENDO Trial (which is very similar to CompassHER2 pCR in terms of study design, drugs, and eligibility). However, patients who received 4 cycles of neoadjuvant THP off study can receive a further 2-4 cycles of chemotherapy postoperatively to meet eligibility for A011801. Patients who participated in EA1181 or MA41 and proceeded to surgery immediately after the de-escalated trial regimen must receive postoperative chemotherapy to complete a total of >= 6 cycles of systemic treatment prior to enrollment on A011801, as outlined above (e.g. 4 cycles pre-operatively, and 2 cycles post-operatively). The postoperative chemotherapy regimen prescribed is at the discretion of the treating oncologist (i.e. 2-4 cycles AC or THP, other). Continuation of trastuzumab + pertuzumab (HP) pre- or post-operatively as maintenance therapy (while awaiting a surgical date or an official pathology report) is allowed for all study participants
• Toxicities related to prior systemic treatment should have resolved or be at baseline, apart from alopecia and peripheral neuropathy =< grade 1
• Adequate excision: surgical removal of all clinically evident disease in the breast and lymph nodes as follows:
• Breast surgery: total mastectomy with no gross residual disease at the margin of resection, or breast-conserving surgery with histologically negative margins of excision
• For patients who undergo breast-conserving surgery, the margins of the resected specimen must be histologically free of invasive tumor and ductal carcinoma in situ (DCIS) as determined by the local pathologist. If pathologic examination demonstrates tumor at the line of resection, additional operative procedures may be performed to obtain clear margins. If tumor is still present at the resected margin after re-excision(s), the patient must undergo total mastectomy to be eligible. Patients with margins positive for classic lobular carcinoma in situ (LCIS) are eligible without additional resection
• Lymph node surgery ** The axilla needs to be evaluated with either sentinel node biopsy or axillary lymph node dissection. If patients have a sentinel lymph node biopsy and sentinel nodes are negative, no further axillary treatment is necessary. If patients have isolated tumor cells (ITCs) in the setting of residual breast disease, at least one of the following is required: axillary lymph node dissection (ALND) or planned nodal irradiation. If patients have micro- or macro-metastatic nodal disease, ALND and planned nodal irradiation are required. Of note, co-enrollment on Alliance A011202 is not allowed
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1
• Absolute neutrophil count (ANC) >= 1,000/mm^3
• Hemoglobin >= 8 g/dL (Note: packed red blood cells [PRBC] transfusion is not permitted to achieve eligibility)
• Platelet count >= 100,000/mm^3
• Creatinine =< 1.5 x upper limit of normal (ULN)
• Total bilirubin =< 1.0 x upper limit of normal (ULN) or direct bilirubin within the institutional normal range for patients with Gilbert's syndrome
• Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) =< 2.5 x upper limit of normal (ULN)
• Screening left ventricular ejection fraction (LVEF) >= 50% on echocardiogram (ECHO) or multiple-gated acquisition (MUGA) after receiving neoadjuvant chemotherapy and no decrease in LVEF by more than 15% absolute percentage points from the pre-chemotherapy LVEF. Or, if pre-chemotherapy LVEF was not assessed, the screening LVEF must be >= 55% after completion of neoadjuvant chemotherapy. Note: LVEF assessment may be repeated once up to 3 weeks following the initial screening assessment to assess eligibility

Exclusion Criteria:

• No adjuvant treatment with any anti-cancer investigational drug within 28 days prior to registration
• Not pregnant and not nursing, because this study involves an agent that has known genotoxic, mutagenic and teratogenic effects. Therefore, for women of childbearing potential only, a negative serum pregnancy test done =< 7 days prior to registration is required
• Patients with known active and/or untreated hepatitis B or hepatitis C or chronic liver disease are ineligible. Patients with a diagnosis of hepatitis B or C that has been treated and cleared and normal liver function are eligible to participate in the study if the other eligibility parameters are met
• Stage IV (metastatic) breast cancer
• History of any prior (ipsi- or contralateral) invasive breast cancer within 3 years of registration
• Patients with ER+ HER2+ residual invasive disease that is lymph node-negative per the surgical pathology report
• Evidence of recurrent disease following preoperative therapy and surgery
• Patients for whom radiotherapy would be recommended for breast cancer treatment but for whom it is contraindicated because of medical reasons (e.g., connective tissue disorder or prior ipsilateral breast radiation)
• History of exposure to the following cumulative doses of anthracyclines: doxorubicin > 240 mg/m^2; epirubicin or liposomal doxorubicin-hydrochloride (Myocet) > 480 mg/m^2. For other anthracyclines, exposure equivalent to doxorubicin > 240 mg/m^2
• Cardiopulmonary dysfunction as defined by any of the following:
• History of National Cancer Institute (NCI) CTCAE version (v) 5.0 grade >= 3 symptomatic congestive heart failure (CHF) or New York Heart Association (NYHA) criteria class >= II
• Angina pectoris requiring anti-anginal medication, serious cardiac arrhythmia not controlled by adequate medication, severe conduction abnormality, or clinically significant valvular disease
• High-risk uncontrolled arrhythmias: i.e., atrial tachycardia with a heart rate > 100/min at rest, significant ventricular arrhythmia (ventricular tachycardia) or higher-grade atrioventricular block (AV)-block (second degree AV-block type 2 [Mobitz 2] or third degree AV-block)
• Significant symptoms (grade >= 2) relating to left ventricular dysfunction, cardiac arrhythmia, or cardiac ischemia while or since receiving preoperative therapy
• History of a decrease in left ventricular ejection fraction (LVEF) to < 40% with prior trastuzumab treatment (e.g., during preoperative therapy)
• Uncontrolled hypertension (systolic blood pressure > 180 mmHg and/or diastolic blood pressure > 100 mmHg)
• Current severe, uncontrolled systemic disease
• Major surgical procedure unrelated to breast cancer or significant traumatic injury within 28 days prior to registration or anticipation of the need for major surgery during the course of study treatment
• History of intolerance, including grade 3 to 4 infusion reaction or hypersensitivity to trastuzumab or murine proteins or any components of the product
• Peripheral neuropathy of any etiology that exceeds grade 1
• Assessment by the investigator as being unable or unwilling to comply with the requirements of the protocol
• Use of a strong CYP3A4 or CYP2C8 inhibitor within 2 weeks, or use of a strong CYP3A4 or CYP2C8 inducer within 5 days prior to registration is prohibited.
• Please note that use of sensitive CYP3A substrates should be avoided two weeks before registration and during study treatment. Additionally, CYP3A4 or CYP2C8 inducers are prohibited as concomitant medications within 5 days following discontinuation of tucatinib treatment. Patients who require medications that are known to be sensitive substrates of CYP3A4 with a narrow therapeutic window should be excluded.

Inclusion Criteria:

Patient has ECOG performance status of 0-1 One or more documented primary oncogenic PIK3CA mutation(s) in blood and/or tumor per local assessment RLY-5836 single agent arm key inclusion criteria
• Disease that is refractory to standard therapy, intolerant to standard therapy, or participant has declined standard therapy.
• A histologically or cytologically confirmed diagnosis of unresectable or metastatic solid tumor Combination arms key inclusion criteria
• Males, postmenopausal females, or pre-/perimenopausal females previously treated with gonadotropin-releasing GnRH agonist at least 4 weeks prior to start of study drug with histologically or cytologically confirmed diagnosis of HR+, HER2- unresectable or metastatic breast cancer that is not amenable to curative therapy.
• Had previous treatment for advanced or metastatic breast cancer with antiestrogen therapy including, but not limited to, selective estrogen receptor degraders (e.g., fulvestrant), selective estrogen receptor modulators (e.g., tamoxifen), and aromatase inhibitors (AI) (letrozole, anastrozole, exemestane)
• Part 1: Prior PI3Kα inhibitor treatment is allowed if taken for < 14 days and not discontinued due to disease progression, hypersensitivity, or ≥ Grade 3 TEAEs.

Exclusion Criteria:

• Part 2: Prior treatment with PI3Kα inhibitors.
• Type 1 or Type 2 diabetes requiring antihyperglycemic medication, or fasting plasma glucose ≥140 mg/dL and glycosylated hemoglobin (HbA1c) ≥7.0%.

Inclusion Criteria:

• Documented radiographic and histopathologic confirmed primary localized invasive breast cancer.
• Histologically documented TNBC (estrogen receptor negative [ER-]/progesterone receptor negative [PR-]/human epidermal growth factor 2 negative [HER2-]) defined as ER-negative and PR-negative (≤5% positive cells stain by IHC for both ER and PR), and negative HER2eu- status, confirmed on tumor sample.
• HER2eu negative will be defined as one of the following criteria:
• IHC 0 or 1+
• Single-probe average HER2 gene copy number of <6 signalsucleus
• Dual-probe fluorescent in-situ hybridization (FISH) HER2eu chromosome 17 (CEP17) non-amplified ratio of <2
• Globo H IHC H-score ≥15 from the residual primary site/or lymph node (if primary site is not available) tumor obtained at time of definitive surgery. Globo H expression will be determined during pre-screening by Central lab. Instructions for submission of slides/tumor tissue blocks are provided in the protocol and study Lab Manual.
• No evidence of metastatic disease in chest, abdomen and pelvis by CT or other adequate imagining during the Screening Phase. Imaging within 3 months prior to randomization is acceptable as baseline scan. Bone scans and imaging of the brain at screening is optional, and should be symptom directed.
• High risk patients with no evidence of disease after completing standard treatment and meeting ONE of the following criteria:
• Neoadjuvant chemotherapy followed by definitive surgery: Residual invasive disease following neoadjuvant chemotherapy defined as: A contiguous focus of residual invasive cancer in the surgical breast measuring ≥1 cm in diameter and/or with residual invasive cancer in at least one axillary node (micrometastases or macrometastases), as determined by local pathology review.
• Definitive surgery followed by adjuvant chemotherapy: Pathological Stage IIB, Stage IIIA , Stage IIIB, or Stage IIIC disease according to the 8th edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual.
• Must have completed a standard taxane, and/or anthracycline-based multi-agent chemotherapy regimen either in the neoadjuvant or adjuvant setting (e.g., National Comprehensive Cancer Network recommended regimens):.
• At least 4 cycles of a standard multi-agent chemotherapy regimen must have been received, unless precluded by toxicities
• Post operative adjuvant capecitabine or a platinum monotherapy in patients with residual disease after neoadjuvant chemotherapy is allowed.
• Randomization must occur within 12 weeks after completion of standard of care treatment (surgery and/or chemotherapy) and within 46 weeks from the date of definitive surgery. Note: patients receiving adjuvant capecitabine or platinum monotherapy after neoadjuvant multi-agent chemotherapy may be randomized and initiate study treatment during (or within 12 weeks after completion of) the adjuvant capecitabine or platinum monotherapy.
• All treatment-related toxicities resolved to Grade <1 on National cancer institute Common Terminology Criteria for Adverse Events (NCI-CTCAE version 5.0) criteria (except hair loss and ≤Grade 2 neuropathy, which are acceptable).
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Females must be either of non-childbearing potential, i.e., surgically sterilized (have documented sterilization, bilateral oophorectomy/salpingectomy at least 3 months before the start of the trial and/or hysterectomy), or one year postmenopausal; or if of childbearing potential must have a negative pregnancy test (urine or serum) at randomization.
• Males and females of childbearing potential and their partners must be willing to use effective contraception during the entire Treatment Phase period and for at least 4 weeks (28 days) after the last dose of study treatment.
• Adequate hematological, hepatic and renal function as defined below:
• Absolute neutrophil count (ANC) ≥1,500/µL
• Platelets ≥75,000/µL
• Hemoglobin ≥8.5g/dL
• Serum creatinine ≤1.5 × upper limit of normal (ULN) or calculated creatinine clearance ≥55 mL/min for subjects with creatinine levels >1.5 × institutional ULN (glomerular filtration rate can also be used in place of creatinine or creatinine clearance may be calculated per institutional standard)
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3 × ULN
• Alkaline Phosphatase (ALP) ≤2.5 × ULN
• Serum total bilirubin ≤1.5 × ULN (unless Gilbert's disease is documented)
• Consent to participate with a signed and dated Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved patient informed consent for the study prior to beginning any specific study procedures.
• Ability to understand and willingness to complete all protocol required procedures.

Exclusion Criteria:

• Local recurrence of or previous history of ipsilateral or contralateral invasive breast cancer within 10 years prior to randomization.
• Definitive clinical or radiologic evidence of metastatic disease
• Synchronous bilateral breast cancer, unless both tumors are confirmed as TNBC.
• Have received any post-operative immunotherapy with antigen, antibody, immune checkpoint inhibitors (Programmed cell death-1 [PD-1]/ Programmed cell death-ligand-1inhibitors [PD-L-1], anti-cytotoxic T lymphocyte associated protein 4 [CTLA 4] therapy), or other anti-cancer vaccines (neoadjuvant receipt of immune checkpoint inhibitors will not be exclusionary if the patient meets all other eligibility criteria).
• Concomitant treatment with approved anticancer therapy or immunotherapy including checkpoint inhibitors (e.g. PD-1 inhibitors) or other investigational therapy, if expected during the study. Adjuvant capecitabine or platinum monotherapy is allowed during the study.
• A history of other malignancies (except non melanoma skin carcinoma, carcinoma in situ of the uterine cervix, follicular or papillary thyroid cancer) within 5 years prior to randomization.
• Have any active autoimmune disease or disorder that requires systemic immunosuppressive/immunomodulatory therapy. NOTE: Autoimmune diseases that are confined to the skin (e.g., psoriasis) that can be treated with topical steroids alone are allowed during the study.
• Oral/parenteral corticosteroid treatment (>5 mg/day of prednisone/equivalent), within 2 weeks prior to randomization or anytime during the study. NOTE: inhaled steroids for treatment of asthma; and topical steroids are allowed during the study.
• Any known uncontrolled concurrent illness that would limit compliance with study requirements, including but not limited to ongoing or active infections, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, psychiatric disorders, or substance abuse.
• Any known hypersensitivity to active/inactive ingredients in the study drug formulation or known severe allergy or anaphylaxis to fusion proteins.
• Prior receipt of a glycoconjugate vaccine for cancer immunotherapy.
• Known history or positive for human immunodeficiency virus (HIV positive), unless on effective anti-retroviral therapy with undetectable viral load within 6 months of therapy (note: HIV testing not required for study entry).
• Known active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection prior to randomization. Patients who have completed curative therapy for HCV are eligible. For patients with evidence of chronic HBV infection, the HBV viral load must be undetectable on suppressive therapy. (note: HBV/HCV testing is not required for study entry).
• Any condition, including significant diseases and/or laboratory abnormalities that would place the patient at unacceptable risk for study participation.
• Currently pregnant or breastfeeding women.
• Currently participating in or has participated in a breast cancer therapeutic clinical trial within 4 weeks (24 days) prior to randomization.

1. Signed, written informed consent obtained prior to any study procedures. 2. Age > 18 years at the time of informed consent. 3. Metastatic solid tumor with ≥ 25% of tumor cells positive for KK-LC-1 by IHC assay. Due to the low frequency of KK-LC-1 expression in most cancers, screening will focus on gastric, NSCLC, TNBC, and cervix cancers. The IHC test will be performed by the Rutgers Cancer Institute of New Jersey, Department of Biorepository Services. 4. HLA-A*01:01 allele by HLA haplotype test. 5. Measureable disease per RECIST Criteria Version 1.1 at time of enrollment. 6. Prior treatment with cancer type-specific stand of care systemic cancer therapy is required. Standard treatment options must be considered and declined. Documentation of rationale is required if a subject is deemed unsuitable for standard therapy. 7. Subjects with < 3 brain metastases that have been treated with surgery or stereotactic radiosurgery are eligible. Lesions that have been treated with stereotactic radiosurgery must be clinically stable for one month before protocol treatment. Patients with surgically resected brain metastases are eligible. 8. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at screening. 9. Negative pregnancy test for women under 55 and all women who have had a menstrual period in the last 12 months. A pregnancy tests is not required for women who have had a bilateral oophorectomy or hysterectomy. 10. Women of child-bearing potential must agree to use adequate contraception (i.e., intrauterine device, hormonal barrier method of birth control; abstinence; tubal ligation or vasectomy) prior to study entry and for four months after treatment. Should a women become pregnant or suspect she is pregnant while she is participating in this study, she should inform her treating physician immediately. 11. Participants must have organ and marrow function as defined below: 1. Leukocytes > 3,000/mcL 2. Absolute neutrophil count > 1,500/mcL 3. Platelets > 100,000/mcL 4. Hemoglobin > 9.0 g/dL 5. Total bilirubin within normal institutional limits except in participants with Gilbert's Syndrome who must have a total bilirubin < 3.0 mg/dL. 6. Serum AST (SGOT)/ALT (SGPT) < 2.5 x ULN 7. Calculated creatinine clearance (CrCl) >50 mL/min/1.73 m2for participants with creatinine levels above institutional normal (by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation). 8. INR or a PTT ≤1.5 X ULN unless the subject is receiving anticoagulant therapy. Subjects on anticoagulant therapy must have a PT or PTT within therapeutic range and no history of severe hemorrhage. 12. Serology:

• HIV antibody negative
• Hepatitis B antigen negative
• Hepatitis C antibody negative or HCV RNC negative (i.e., no current HCV infection) 13. More than four weeks must have elapsed since any prior systemic therapy or radiotherapy at the time the patient receives the KK-LC-1 TCR T cells. Adverse events from prior therapy must have resolved to≤ grade 1 according to CTCAE Version 5 or have demonstrated clinical stability and meet the eligibility criteria for the protocol. 14. Oxygen saturation ≥ 92% on room air. 15. Left ventricular ejection fraction ≥45% by echocardiogram or MUGA for patients 50 years of age or older.

Inclusion Criteria:

• Breast cancer patients with biopsy proven invasive cancer
• Clinically and radiographically node negative
• No indication of metastatic disease
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1
• Synchronous bilateral invasive cancer allowed
• Negative serum pregnancy test within one month from the radiation therapy (RT) boost delivery
• Willingness to participate in the clinical trial and adhere to the study protocol
• Individuals of all races, genders and ethnic groups are eligible for this trial

Exclusion Criteria:

• Need for neoadjuvant chemotherapy
• Inflammatory breast cancer (cT4)
• Multicentric tumor
• Prior ipsilateral breast or thoracic RT
• Contraindication for baseline magnetic resonance imaging (MRI)
• Contraindication for surgery
• Distant metastatic disease
• Other synchronous cancer (besides bilateral breast)
• Contraindication to radiation therapy (presence of scleroderma or other collagen vascular disease)
• Any serious or uncontrolled medical disorder that, in the opinion of the investigator, may increase the risk associated with study participation or study drug administration, impair the ability of the subject to receive protocol therapy, or interfere with the interpretation of study results

Eligibility Criteria to Collect Optional Correlative Blood and Tissue at 1st Recurrence

• Written informed consent (stage I) and HIPAA authorization for release of personal health information obtained prior to performing any study-specific procedures. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.
• Male or female age ≥ 18 years at the time of consent.
• Patient has a histologically and/or cytologically confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer based on the most recently analyzed tissue sample and all tested by local laboratory.
• Patient has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (FISH, CISH, or SISH) test is required by local laboratory testing and based on the most recently analyzed tissue sample.
• Patient has locoregional recurrence of breast cancer: locoregional recurrence is defined as invasive recurrence in the ipsilateral breast, axilla, regional nodes, and chest wall.

  Inclusion Criteria for Treatment Phase:

  Subject must meet all of the following applicable inclusion criteria to participate in this study:
  • Written informed consent (stage II/ main consent) and HIPAA authorization for release of personal health information obtained prior to performing any study-specific screening procedures. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.
  • Male or female age ≥ 18 years at the time of consent. NOTE: Both pre- and post-menopausal women are eligible. Pre-menopausal status is defined as:
  • -Age <60 and amenorrhea for the last 12 or more months(in the absence of chemotherapy, tamoxifen, toremifen, or ovarian suppression) and FSH and estradiol in the postmenopausal range per local normal range.
  • ECOG Performance Status of 0-1 within 28 days prior to registration.
  • If patient is receiving tamoxifen or toremifene, a washout period of 28 days prior to registration is required.
  • Patient has a histologically and/or cytologically confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer based on the most recently analyzed tissue sample and all tested by local laboratory.
  • Patient has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (FISH, CISH, or SISH) test is required by local laboratory testing and based on the most recently analyzed tissue sample.
  • Patients have had adequate local treatment for locoregional recurrence (LRR) of breast cancer.
  • Locoregional recurrence is defined as recurrence in the ipsilateral breast, axilla, regional lymph nodes, and chest wall.
  • Local treatment is defined as surgery and/or radiation therapy if indicated.
  • Adequate local therapy is surgery with negative microscopic margins. Radiation therapy is mandated for patients with microscopically involved margins and recommended for all patients who had not received radiotherapy as part of their primary treatment.
  • Patients who have distant metastatic disease will not be eligible.
  • Prior treatment with neo- adjuvant and adjuvant chemotherapy and ET is allowed.
  • Patients must enroll within 6 months of the last local treatment, surgery or radiation, whichever occurred last.
  • Patient has no contraindication for the adjuvant ET in the trial and is planned to be treated with ET. Subjects who have already started adjuvant ET within 3 months prior to registration are allowed.
  • Demonstrate adequate organ function as defined in the table below; all screening labs to be obtained within 28 days prior to registration.
  • Hematological
  • Absolute Neutrophil Count (ANC): ≥ 1.5 x 109/L
  • Platelets: ≥ 100 x 109/L
  • Hemoglobin (Hgb): ≥ 9.0 g/dL
  • Renal
  • --Estimated glomerular filtration rate (eGFR): ≥ 30 mL/min/1.73m2 according to the Modification of Diet in Renal Disease (MDRD) formula
  • Hepatic
  • Bilirubin: < upper limit of normal (ULN) except for patients with Gilbert's syndrome who may only be included if the total bilirubin is ≤ 3.0 × ULN or direct bilirubin ≤ 1.5 × ULN
  • Aspartate aminotransferase (AST): ≤ 2.5 × ULN except for patients with liver metastasis, who are only included if the AST is < 5 × ULN
  • Alanine aminotransferase (ALT): ≤ 2.5 × ULN except for patients with liver metastasis, who are only included if the ALT is < 5 × ULN
  • Coagulation
  • --International Normalized Ratio (INR) : ≤ 1.5 × ULN (unless is receiving anticoagulants and the INR is within the therapeutic range of intended use for that anticoagulant within 7 days prior to the first dose of study drug)
  • Electrolytes ---Potassium, Magnesium, and Total Calcium (corrected for serum albumin): Within normal limits or corrected to within normal limits with supplements.
  • Standard 12-lead ECG values defined as
  • QTcF interval at screening < 450 msec (QT interval using Fridericia's correction)
  • Resting heart rate 50-90 bpm (determined from the ECG)
  • Females of childbearing potential who are sexually active with a male able to father a child must have a negative pregnancy test (serum or urine) within 14 days prior to registration and must be willing to use a highly effective method of contraception that does not contain estrogen and/or progesterone. See the protocol for definition of childbearing potential.
  • As determined by the enrolling physician or protocol designee, ability of the subject to understand and comply with study procedures for the entire length of the study.
  • Ability to swallow and retain oral medication.

  Exclusion Criteria for Treatment Phase:

  Subjects meeting any of the criteria below may not participate in the study:
  • Patient with a known hypersensitivity to any of the excipients of ribociclib.
  • Patient who has received prior CDK4/6 inhibitor for recurrent disease. Patients who received a CDK4/6 inhibitor in the adjuvant setting may participate if they have been off therapy for at least 1 year prior to diagnosis of recurrent disease.
  • Patient has had major surgery within 14 days prior to starting study drug or has not recovered from major side effects.
  • Pregnant or breastfeeding or planning to become pregnant during the trial (NOTE: breast milk cannot be stored for future use while the mother is being treated on study).
  • Patients with a prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen are not eligible for this trial.
  • Patients with distant metastases of breast cancer beyond regional lymph nodes as defined by AJCC (8th edition).
  • Treatment with any investigational drug within 30 days prior to registration or participation in any other type of medical research judged not to be scientifically or medically compatible with this study. Enrollment or planned enrollment in another study that does not involve an investigational drug will be allowed at the discretion of the treating investigator.
  • Patient has impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of the study drugs (e.g., uncontrolled ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection).
  • Patient has any other concurrent severe and/or uncontrolled medical condition that would, in the investigator's judgment, cause unacceptable safety risks, contraindicate patient participation in the clinical study or compromise compliance with the protocol: (e.g., chronic pancreatitis, chronic active hepatitis, HIV, active untreated or uncontrolled fungal, bacterial or viral infections, etc.)
  • Clinically significant, uncontrolled heart disease and/or cardiac repolarization abnormality, including any of the following:
  • History of documented myocardial infarction (MI), angina pectoris, symptomatic pericarditis, or coronary artery bypass graft (CABG) within 6 months prior to study entry
  • Documented cardiomyopathy
  • Left Ventricular Ejection Fraction (LVEF) < 50% as determined by Multiple Gated acquisition (MUGA) scan or echocardiogram (ECHO)
  • Long QT syndrome or family history of idiopathic sudden death or congenital long QT syndrome, or any of the following:
  • Risk factors for Torsades de Pointe (TdP) including uncorrected hypocalcemia, hypokalemia or hypomagnesemia, history of cardiac failure, or history of clinically significant/symptomatic bradycardia
  • Concomitant medication(s) with a known risk to prolong the QT interval and/or known to cause Torsades de Pointe that cannot be discontinued or replaced by safe alternative medication (e.g., within 5 half-lives or 7 days prior to starting study drug)
  • Inability to determine the QTcF interval
  • Clinically significant cardiac arrhythmias (e.g., ventricular tachycardia), complete left bundle branch block, high-grade AV block (e.g., bifascicular block, Mobitz type II and third-degree AV block)
  • Systolic Blood Pressure (SBP) >160 or <90 mmHg
  • Patient is currently receiving any of the following substances and cannot be discontinued 7 days prior to Cycle 1 Day 1:
  • Concomitant medications, herbal supplements, and/or fruits (e.g., grapefruit, pummelos, star fruit, Seville oranges) and their juices that are strong inducers or inhibitors of CYP3A4/5,
  • Medications that have a narrow therapeutic window and are predominantly metabolized through CYP3A4/5.
  • Patient is currently receiving or has received systemic corticosteroids ≤ 2 weeks prior to starting study drug, or who have not fully recovered from side effects of such treatment. Note: The following uses of corticosteroids are permitted: a short duration (<5 days) of systemic corticosteroids; any duration of topical applications (e.g. for rash), inhaled sprays (e.g., for obstructive airways diseases), eye drops or local injections (e.g., intra-articular).
  • Patient with an uncontrolled psychiatric condition that, in the investigator's judgment, may cause unacceptable safety risks, impede research integrity and compliance, or interfere with the objectives of the study.

Eligibility Criteria:

Inclusion criteria for Part A and B (HER2-negative) and Part Z (HER2-positive) cohorts:

1. Written informed consent, according to local guidelines, signed and dated by the patient or by a legal guardian prior to the performance of any study-specific procedures, sampling, or analyses 2. Women and men at least 18 years-of-age at the time of signature of the informed consent form (ICF) 3. Histologically documented locally advanced or metastatic breast cancer 4. Triple-negative breast cancer (TNBC) patients should have received at least 1 but no more than 5 prior lines of chemotherapy in the metastatic setting 5. Parts A and B patients only: Patients with HR+ HER2-negative MBC should have received prior treatment with endocrine therapy +CDK 4/6 inhibitor. No limit to prior endocrine therapy regimens, but no more than 2 prior chemotherapy regimens in the metastatic setting are allowed. HR+ = Estrogen receptor (ER) and/or Progesterone (PgR) positivity that are defined as ≥1% of cells expressing HR via IHC analysis. HER2 negativity is defined as either of the following: IHC 0, IHC 1+, or IHC 2+/in situ hybridization (ISH) negative. 6. Part B patients only: Patients with HER2-negative MBC will be included into one of the following 2 subgroups: 1) MBC HR+, HER2-, regardless of HER3 expression, who have received trastuzumab deruxtecan and/or sacituzumab govitecan, or, 2) mTNBC, regardless of HER3 expression, who have received sacituzumab govitecan and/or datopotamab deruxtecan. 7. Part Z patients only: should have documented HER2-positive expression as per American Society of Clinical Oncology - College of American Pathologists guidelines based on local testing. 8. Part Z patients only: should have had prior treatment with at least 2 anti-HER2 therapies, 1 of which must be trastuzumab deruxtecan. These patients must have experienced disease progression after receiving trastuzumab deruxtecan. 9. At least 1 measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 (bone-only disease excluded) 10. Patients who have received radiation or surgery for brain metastases are eligible if therapy was completed ≥4 weeks prior to initiation of study treatment (2 weeks for patients who received palliative radiation therapy), there is no evidence of central nervous system disease progression on a scan or mild neurologic symptoms, and there is no requirement for chronic corticosteroid therapy for the treatment of brain metastases 11. Willingness to undergo pre-treatment biopsy and on-treatment biopsies; must have a tumor amenable to pre-treatment biopsy (unless archived tissue is available and was obtained within 2 months prior to starting treatment) and on-treatment biopsy (excludes bone lesions and previously irradiated lesions) 12. Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1 13. Has adequate organ function within 7 days before the start of study treatment, defined as:
• Platelet count ≥100 × 109/L
• Hemoglobin (Hb) ≥9 g/dL (transfusion and/or growth factor support allowed)
• Absolute neutrophil count ≥1.5 × 109/L
• Prothrombin time (PT) and partial thromboplastin time (PTT) ≤1.5 × the upper limit of normal (ULN), except for patients on coumadin-derivative anticoagulants or other similar anticoagulant therapy, who must have PT-international normalized ratio (INR) within therapeutic range as deemed appropriate by the Investigator
• Serum creatinine ≤1.5 × ULN, or creatinine clearance ≥50 mL/min as calculated using the modified Cockcroft-Gault equation; confirmation of creatinine clearance is only required when creatinine is >1.5 × ULN
• AST/ALT ≤3 × ULN (if liver metastases are present, ≤5 × ULN)
• Total bilirubin ≤1.5 × ULN if no liver metastases or <3 × ULN in the presence of documented Gilbert's syndrome or liver metastases
• Serum albumin ≥2.5 g/dL 14. Male patients with female partners of childbearing potential and female patients of childbearing potential are required to use two forms of acceptable contraception, including one barrier method, during their participation in the study and for at least 7 months following last dose. Male patients must also refrain from donating sperm during their participation in the study.

Exclusion Criteria

Patients who meet any of the following criteria will be excluded from study entry: Exclusion criteria for Parts A and B (HER2-negative) and Part Z (HER2-positive) cohorts: 1. Treatment with any of the following:
• Any systemic anti-cancer chemotherapy, small molecule, biologic, hormonal agent, or immune checkpoint inhibitor therapy from a previous treatment regimen or clinical study within 21 days prior to the first dose of patritumab deruxtecan
• Prior treatment with any HER3-targeting agent
• Major surgery (excluding placement of vascular access) within 4 weeks of the first dose of study drug treatment
• Radiotherapy treatment to more than 30% of the bone marrow or with a wide field of radiation within 4 weeks of the first dose of study drug treatment, or palliative radiation therapy within 2 weeks of the first dose of study drug treatment
• Chloroquine /hydroxychloroquine ≤14 days prior to the first dose of study drug treatment 2. Has any hypersensitivity to drug substances or inactive ingredients in drug product 3. Has any history of ILD (including pulmonary fibrosis or radiation pneumonitis), has clinically significant ILD, or is suspected to have such disease by imaging during screening. If imaging findings are unlikely to indicate a history of pneumonitis, then the Investigator should discuss the considerations with the Medical Monitor about potential enrollment and record the reasoning in the source documentation. 4. Clinically severe pulmonary compromise (based on Investigator's assessment) resulting from intercurrent pulmonary illnesses including, but not limited to:
• Any underlying pulmonary disorder (e.g., pulmonary emboli, severe asthma, severe chronic obstructive pulmonary disease, restrictive lung disease, pleural effusion)
• Any autoimmune, connective tissue or inflammatory disorder with pulmonary involvement (e.g., rheumatoid arthritis, Sjögren's syndrome, sarcoidosis) OR prior pneumonectomy 5. With the exception of alopecia, any unresolved toxicities from prior therapy greater than Common Terminology Criteria for Adverse Events (CTCAE) Grade 1 or baseline at the time of starting study treatment. Note: patients with chronic Grade 2 toxicities who are asymptomatic or adequately managed with stable medication may be eligible with approval by the Medical Monitor. 6. Leptomeningeal metastases or evidence of spinal cord compression or brain metastases, defined as being clinically active and symptomatic, or requiring therapy with corticosteroids or anticonvulsants to control associated symptoms. Patients with clinically inactive or treated brain metastases who are asymptomatic (i.e., without neurologic signs or symptoms and do not require treatment with corticosteroids or anticonvulsants) may be included in the study. Patients must have a stable neurologic status for at least 2 weeks prior to Cycle 1 Day 1. 7. Women who are pregnant, nursing, or plan to become pregnant while in the study and for at least 7 months after the last administration of study treatment 8. Men who plan to father a child while in the study and for at least 7 months after the last administration of study treatment 9. Uncontrolled or significant cardiovascular disorder prior to Cycle 1 Day 1, including:
• Mean resting corrected QT interval using Fridericia's formula (QTcF) prolongation to >470 ms for females and >450 ms for males in three successive screening measurements
• Patients with a left ventricular ejection fraction (LVEF) <50%
• Resting systolic blood pressure >180 mmHg or diastolic blood pressure >110 mmHg).
• Documented myocardial infarction within 6 months
• Congestive heart failure (New York Heart Association ≥ Grade 2 within 28 days 10. Has known clinically significant corneal disease from prior therapies such as drug-induced keratitis 11. Is receiving chronic systemic corticosteroids dosed at >10 mg prednisone or equivalent anti-inflammatory activity or any form of immunosuppressive therapy prior to Cycle 1 Day 1. Patients who require use of bronchodilators, inhaled or topical steroids, or local steroid injections may be included in the study. 12. As judged by the Investigator, any evidence of severe or uncontrolled systemic diseases, including uncontrolled hypertension, uncontrolled diabetes mellitus, active bleeding diatheses, or active infection, including hepatitis B, hepatitis C, and human immunodeficiency virus. Screening for chronic conditions is not required. 13. Presence of other active invasive cancers other than the one treated in this study within 3 years prior to screening, except appropriately treated basal cell carcinoma of the skin, in situ carcinoma of uterine cervix, or other local tumors considered cured by local treatment 14. Psychological, familial, sociological, or geographical conditions that do not permit compliance with the protocol and/or follow-up procedures outlined in the protocol Additional exclusion criteria only for Parts A and B (HER2-negative) cohorts: 15. Patients with HER2+ breast cancer per ASCO-CAP guidelines 16. Part A only: Prior treatment with an antibody drug conjugate that consists of an exatecan derivative that is a topoisomerase I inhibitor (e.g., trastuzumab deruxtecan, DS-1062a [datopotamab deruxtecan], and DS-7300a [B7-H3 DXd-ADC]) 17. Part B patients only: Prior treatment with trastuzumab deruxtecan, sacituzumab govitecan, and/or datopotamab deruxtecan with any of the following:
• A severe reaction or severe tolerability issues that necessitated stopping treatment with the therapy
• Any unresolved toxicities from the prior therapy greater than Grade 1, with the exception of alopecia Additional exclusion criteria only for Part Z (HER2-positive) cohort: 18. Treatment with any of the following:
• Prior treatment with an antibody drug conjugate that consists of an exatecan derivative that is a topoisomerase I inhibitor except trastuzumab deruxtecan
• Prior treatment with trastuzumab deruxtecan within 4 weeks prior to the first dose of patritumab deruxtecan 19. Uncontrolled or significant cardiovascular disease, including history of myocardial infarction within 6 months before enrollment 20. A severe reaction or severe tolerability issues that necessitated stopping treatment with trastuzumab deruxtecan 21. Any unresolved toxicities from prior therapy with trastuzumab deruxtecan

Inclusion Criteria:

• Centrally confirmed HER2+ breast carcinoma according to the 2018 American Society of Clinical Oncologists (ASCO) College of American Pathologists (CAP) guidelines prior to randomization (defined as a 3+ score on immunohistochemistry (IHC) and/or 2+ IHC and concurrent positive by ISH).
• Have unresectable locally advanced or metastatic disease.
• If recurrent (after [neo]adjuvant therapy), must be at least 6 month treatment free from any trastuzumab and pertuzumab received in the early breast cancer setting for advanced HER2+ disease.
• Have received 4-8 cycles of pre-study induction therapy including only trastuzumab, pertuzumab, and taxane as first-line of therapy for the treatment of advanced breast cancer prior to study enrollment. Participants are eligible provided they are without evidence of disease progression following completion of induction therapy.
• Known hormone receptor status (per local guidelines; may be hormone receptor positive [HR+] or negative [HR-])
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
• CNS Inclusion - Based on screening contrast-enhanced brain magnetic resonance imaging (MRI), participants may have any of the following:
• No evidence of brain metastases
• Untreated brain metastases which are asymptomatic not needing immediate local treatment and, if identified on prior brain imaging, without evidence of progression since starting first-line induction therapy with trastuzumab, pertuzumab, and taxane
• Previously treated brain metastases which are asymptomatic
• Brain metastases previously treated with local therapy must not have progressed since treatment

Exclusion Criteria:

• Prior treatment with any tyrosine kinase inhibitor targeting HER2 and/or epidermal growth factor receptor (EGFR) including pyrotinib, lapatinib, tucatinib, neratinib, and afatinib (except neratinib if given in extended adjuvant setting and ≥ 12 months have elapsed since last neratinib dose prior to start of study drug)
• Unable to undergo contrast-enhanced MRI of the brain
• CNS Exclusion - Based on screening brain MRI and clinical assessment
• Symptomatic brain metastasis after CNS-directed local therapy
• Progression of brain metastases since starting first line trastuzumab, pertuzumab, and taxane
• Ongoing use of systemic corticosteroids at a total daily dose of >2 mg of dexamethasone (or equivalent)
• Any untreated brain lesion in an anatomic site which may pose risk to participant
• Known or suspected leptomeningeal disease (LMD)
• Poorly controlled (>1/week) seizures, or other persistent neurologic symptoms

Inclusion Criteria:

• Have a diagnosis of ER+, HER2- early-stage, resected, invasive breast cancer without evidence of distant metastasis.
• Participants must have received at least 24 months but not more than 60 months of any adjuvant ET, from time of adjuvant ET initiation.
• Participants may have received (neo) adjuvant chemotherapy and/or targeted therapy with a CDK4/6- or PARP- inhibitor.
• Must have an increased risk of disease recurrence based on clinical-pathological risk features.
• Have a Performance Status of 0 or 1 on the Eastern Cooperative Oncology Group scale.
• Have adequate organ function.

Exclusion Criteria:

• Have any evidence of metastatic disease (including contralateral ALN) or inflammatory breast cancer at primary breast cancer diagnosis.
• Participants with more than a 6-month consecutive gap in therapy during the course of prior adjuvant ET.
• Participants who have completed or discontinued prior adjuvant ET >6 months prior to screening.
• Participants with a history of previous breast cancer are excluded, with the exception of ipsilateral DCIS treated by locoregional therapy alone ≥5 years ago.
• Pregnant, breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the screening visit through 180 days after the last dose of study intervention.
• Participant has previously received ET of any duration for breast cancer prevention (tamoxifen or AIs) or raloxifene.
• Participants with a history of any other cancer.
• Have serious preexisting medical conditions that, in the judgment of the investigator, would preclude participation in this study.

Key Inclusion Criteria:

• Age > 18 years, with residual invasive triple negative breast cancer (TNBC) in the breast or lymph nodes after neoadjuvant therapy and surgery:
• TNBC criteria for the study is defined as estrogen receptor (ER) and progesterone receptor (PR) < 10%, human epidermal growth factor receptor 2 (HER2)-negative per American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) guidelines (immunohistochemistry (IHC) and/or in situ hybridization (ISH)).
• Adequate excision and surgical removal of all clinically evident of disease in the breast and/or lymph nodes and have adequately recovered from surgery.
• Submission of both pre-neoadjuvant treatment diagnostic biopsy and resected residual invasive disease tissue.
• Eastern Cooperative Oncology Group (ECOG) performance status 0-1.
• Individuals must have received appropriate radiotherapy and have recovered prior to starting study treatment.
• Adequate organ function.

Key Exclusion Criteria:

• Stage IV (metastatic) breast cancer as well as history of any prior (ipsi- or contralateral) invasive breast cancer.
• Prior treatment with another stimulatory or coinhibitory T-cell receptor agent (eg, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), OX-40, cluster of differentiation 137 (CD137), prior treatment with any HER2-directed agent.
• Evidence of recurrent disease following preoperative therapy and surgery.
• Prior treatment with topoisomerase 1 inhibitors or antibody-drug conjugates (ADCs) containing a topoisomerase inhibitor.
• Individuals with known germline breast cancer gene (BRCA) mutations.
• Myocardial infarction or unstable angina pectoris within 6 months of enrollment or history of serious ventricular arrhythmia (ie, ventricular tachycardia or ventricular fibrillation), high-grade atrioventricular block, or other cardiac arrhythmias or Left ventricular ejection fraction (LVEF) of < 50%
• Active serious infections requiring anti-microbial therapy. Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Key Inclusion Criteria:

• Individuals with locally advanced, inoperable, or metastatic triple-negative breast cancer (TNBC) who have not received previous systemic therapy for advanced disease and whose tumors are programmed cell death ligand 1 (PD-L1) positive at screening.
• Individuals must have completed treatment for Stage I to III breast cancer, if indicated, and ≥ 6 months must have elapsed between completion of treatment with curative intent and first documented local or distant disease recurrence.
• Individuals presenting with de novo metastatic TNBC are eligible for this study.
• TNBC status and tumor PD-L1 combined positive score (CPS) will be confirmed centrally on a recent or archival tumor specimen.
• Individuals must have measurable disease by computed tomography (CT) or magnetic resonance imaging (MRI) as per Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 criteria as evaluated locally.
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.
• Demonstrates adequate organ function
• Male and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use protocol-specified method(s) of contraception.
• Individuals with HIV must be on antiretroviral therapy (ART) and have a well-controlled HIV infection/disease.

Key Exclusion Criteria:

• Positive serum pregnancy test or women who are lactating.
• Received prior therapy with an agent directed to another stimulatory or coinhibitory T-cell receptor.
• Individuals may not have received systemic anticancer treatment within the previous 6 months or radiation therapy within 2 weeks prior to enrollment.
• Individuals may not be participating in a study with an investigational agent or investigational device within 4 weeks prior to randomization. Individuals participating in observational studies are eligible.
• Have previously received topoisomerase 1 inhibitors or antibody drug conjugates containing a topoisomerase inhibitor.
• Have an active second malignancy.
• Have active serious infection requiring antibiotics.
• Individuals positive for HIV-1 or 2 with a history of Kaposi sarcoma and/or Multicentric Castleman Disease.
• Have active hepatitis B virus (HBV) or hepatitis C virus (HCV) infection.
• Has an active autoimmune disease that has required systemic treatment in the past 2 years. Note: Other protocol defined Inclusion/Exclusion criteria may apply.