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:

• 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.

• 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 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:

• A patient cannot be considered eligible for this study unless ALL of the following conditions are met.
• The patient or a legally authorized representative must provide study-specific informed consent prior to pre-entry and, for patients treated in the U.S., authorization permitting release of personal health information.
• Female patients must be greater than or equal to 18 years of age.
• Patients must be premenopausal (evidence of functioning ovaries) at the time of pre-entry. For study purposes, premenopausal is defined as:
• Age 50 years or under with spontaneous menses within 12 months; or
• Age greater than 50-60 years with spontaneous menses within 12 months plus follicle-stimulating hormone (FSH) and estradiol levels in the premenopausal range; or
• Patients with amenorrhea due to IUD or prior uterine ablation must have FSH and estradiol levels in the premenopausal range; or
• Patients with prior hysterectomy must have FSH and estradiol levels in the premenopausal range.
• The patient must have an ECOG performance status of less than or equal to 2 (or Karnofsky greater than or equal to 60%).
• Patients may have ipsilateral or contralateral synchronous breast cancer if the highest stage tumor meets entry criteria, and the other sites of disease would not require chemotherapy or HER2-directed therapy.
• Patients may have multicentric or multifocal breast cancer if the highest stage tumor meets entry criteria, and the other sites of disease would not require chemotherapy or HER2-directed therapy.
• Patient may have undergone a total mastectomy, skin-sparing mastectomy, nipple-sparing mastectomy, or a lumpectomy.
• For patients who undergo a lumpectomy, the margins of the resected specimen or re-excision must be histologically free of invasive tumor and DCIS (ductal carcinoma in situ) with no ink on tumor as determined by the local pathologist. If pathologic examination demonstrates tumor at the line of resection, additional excisions may be performed to obtain clear margins. Positive posterior margin is allowed if surgeon deems no further resection possible. (Patients with margins positive for LCIS (lobular carcinoma in situ) are eligible without additional resection.)
• For patients who undergo mastectomy, the margins must be free of residual gross tumor. (Patients with microscopic positive margins are eligible if post-mastectomy RT (radiation therapy) of the chest wall will be administered.)
• Patient must have undergone axillary staging with sentinel node biopsy (SNB), targeted axillary dissection (TAD), or axillary lymph node dissection (ALND).
• The following staging criteria must be met postoperatively according to AJCC 8th edition criteria:
• By pathologic evaluation, primary tumor must be pT1-3. (If N0, must be T1c or higher.)
• By pathologic evaluation, ipsilateral nodes must be pN0 or pN1 (pN1mi, pN1a, pN1b, pN1c).
• Patients with positive isolated tumor cells (ITCs) in axillary nodes will be considered N0 for eligibility purposes.
• Patients with micrometastatic nodal involvement (0.2-2 mm) will be considered N1.
• Oncotype DX RS (recurrence score) requirements*:
• If node-negative:
• Oncotype DX RS must be RS 21-25, or
• Oncotype DX RS must be 16-20 and disease must be high clinical risk, defined as: low histologic grade with primary tumor size greater than 3 cm, intermediate histologic grade with primary tumor size greater than 2 cm, or high histologic grade with primary tumor size greater than 1 cm.
• If 1-3 nodes involved:
• Oncotype DX RS must be less than 26. * Patients with a "Low Risk" or "MP1" MammaPrint (a genomic test that analyzes the activity of certain genes in early-stage breast cancer) result must have eligibility assessed with an Oncotype DX RS at pre-entry (see Section 3.1). Blocks or unstained slides must be sent to the Genomic Health centralized laboratory for testing at no cost to these patients. If MammaPrint High Risk or MP2, these patients are not eligible.
• The tumor must be ER and/or PgR-positive (progesterone receptor) by current ASCO/CAP guidelines based on local testing results. Patients with greater than or equal to 1% ER and/or PgR staining by IHC will be classified as positive.
• The tumor must be HER2-negative by current ASCO/CAP (American Society of Clinical Oncology/College of American Pathologists) guidelines based on local testing results.
• The interval between the last surgery for breast cancer (including re-excision of margins) and pre-entry must be no more than 16 weeks.
• Short course of endocrine therapy of less than 6 weeks duration before pre-entry is acceptable either as neoadjuvant or adjuvant therapy. An Oncotype DX RS must be performed on core biopsy specimen obtained prior to initiation of neoadjuvant endocrine therapy if received.
• Patients with a prior or concurrent non-breast malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial. This would include prior cancers treated with curative intent.
• HIV-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial.
• Radiation therapy should be used according to standard guidelines; the intended radiation therapy should be declared prior to pre-entry.

Exclusion Criteria:

• • Definitive clinical or radiologic evidence of metastatic disease.
• pT4 (pathological state) tumors, including inflammatory breast cancer.
• History of ipsilateral or contralateral invasive breast cancer. (Patients with synchronous and/or previous DCIS or LCIS are eligible.)
• If prior ipsilateral DCIS was treated with lumpectomy and XRT (ionizing radiation therapy), a mastectomy must have been performed for the current cancer.
• Life expectancy of less than 10 years due to co-morbid conditions in the opinion of the investigator. Known results from most recent lab studies obtained as part of routine care prior to study entry showing ANY of the following values:
• ANC (absolute neutrophil count) less than 1200/mm3;
• Platelet count less than 100,000/mm3;
• Hemoglobin less than 10 g/dL;
• Total bilirubin greater than ULN (upper limit of normal) for the lab or greater than 1.5 x ULN for patients who have a bilirubin elevation due to Gilbert's disease or similar syndrome involving slow conjugation of bilirubin;
• AST(aspartate aminotransferase)(SGOT)/ALT (alanine transminase)(SGPT): greater than 3 × institutional ULN;
• Renal function of GFR (glomular filtration rate) less than 30 mL/min/1.73m2.
• Patients with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, patients should be class 2B or better.
• Non-epithelial breast malignancies such as sarcoma or lymphoma.
• Any treatment with radiation therapy, chemotherapy, or biotherapy administered for the currently diagnosed breast cancer prior to pre-entry. (Patients with prior ET of more than 6 weeks duration for treatment of this cancer are not eligible.) Prior tamoxifen given for breast cancer prevention is allowed. Prior AI or GnRH for fertility preservation is allowed.
• Hormonally based contraceptive measures must be discontinued prior to pre-entry (including progestin/progesterone IUDs).
• Patients with evidence of chronic hepatitis B virus (HBV) infection are ineligible unless the HBV viral load is undetectable on suppressive therapy. Patients with a history of hepatitis C virus (HCV) infection are ineligible unless they have been treated and cured or have an undetectable HCV viral load if still on active therapy.
• Pregnancy or lactation at the time of pre-entry. (Note: Pregnancy testing according to institutional standards for women of childbearing potential must be performed within 2 weeks prior to pre-entry.)
• Other conditions that, in the opinion of the investigator, would preclude the patient from meeting the study requirements or interfere with interpretation of study results.

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:

• Able to understand and give written informed consent.
• Must have adequate tumor tissue sample preferably from locally recurrent or metastatic site.
• Documented evidence of HR+ metastatic breast cancer (mBC) confirmed with the most recently available tumor biopsy preferably from a locally recurrent or metastatic site.
• Documented evidence of HER2- status.
• Documented PD by computed tomography (CT) or magnetic resonance imaging during or after the most recent therapy per RECIST v1.1 criteria.
• Candidate for the first chemotherapy in the locally advanced or metastatic setting.
• Eligible for capecitabine, nab-paclitaxel, or paclitaxel.
• Individuals must have at least one of the following:
• Disease progression on at least 2 or more previous lines of endocrine therapy (ET) with or without a targeted therapy in the metastatic setting.
• Disease recurrence while on the first 24 months of starting adjuvant ET will be considered a line of therapy; these individuals will only require 1 line of ET in the metastatic setting.
• Disease progression within 6 months of starting first-line ET with or without a cyclin-dependent kinase (CDK) 4/6 inhibitor (if ineligible or if unable to access a CDK 4/6 inhibitor) in the metastatic setting.
• Disease recurrence while on the first 24 months of starting adjuvant ET with CDK 4/6 inhibitor and if the individual is no longer a candidate for additional ET in the metastatic setting.
• Individuals may have received prior targeted therapies, including but not limited to PARP inhibitors (for those with germline BRCA1 or BRCA2 mutations), phosphatidylinositol 3-kinase (PI3K) inhibitors (for those with PIK3CA mutations), or mammalian target of rapamycin (mTOR) inhibitors. However, individuals can no longer be candidates for additional endocrine treatment with or without targeted therapies.
• Individuals with HIV must be on antiretroviral therapy (ART) and have a well-controlled HIV infection/disease.
• Demonstrates adequate organ function.
• Male individuals and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use protocol-specified method(s) of contraception.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

Key Exclusion Criteria:

• Progressive disease within 6 months of completing (neo)adjuvant chemotherapy.
• Locally advanced metastatic breast cancer (mBC) (Stage IIIc) in individuals who are candidates for curative intent therapy at the time of study enrollment.
• Current enrollment in another clinical study and use of any investigational device or drug (drugs not marketed for any indication) either within 5 half-lives or 28 days prior to randomization, whichever is longer.
• Use of investigational drugs in the category of Selective Estrogen Receptor Degraders are acceptable if last dose was longer than 14 days prior to randomization.
• Received any prior treatment (including antibody-drug conjugate (ADC)) containing a chemotherapeutic agent targeting topoisomerase I.
• Received any prior treatment with a trophoblast cell-surface antigen 2 (Trop-2)-directed ADC.
• Have an active second malignancy.
• Have an active serious infection requiring antibiotics.
• Have active hepatitis B virus (HBV) or hepatitis C virus (HCV).
• Individuals positive for human immunodeficiency virus type 1/2 (HIV-1 or -2) with a history of Kaposi sarcoma and/or Multicentric Castleman Disease.
• Have a positive serum pregnancy test or are breastfeeding for individuals who are assigned female at birth. Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Inclusion Criteria:

• Self-identification as a staff member or patient who has had breast cancer in a participating practice

Exclusion Criteria:

• Unable to speak, understand and/or read English
• Unable to provide informed consent

Inclusion Criteria:

• Subject is considered an adult according to local regulation at the time of signing the informed consent form (ICF).
• Subject has measurable disease by RECIST Version 1.1.
• Subject has accessible archival tumor tissue from either the primary tumor or a metastatic site, for which source and availability have been confirmed prior to study treatment. If no archival tumor tissue is available, the subject will have a biopsy to obtain tumor tissue prior to study treatment. If the subject is unable to undergo a biopsy due to safety concerns, enrollment into the study must be discussed with the medical monitor.
• For cohort 9 only: Subject should submit archival or fresh tumor tissue sample for programmed cell death-ligand 1 (PD-L1) central testing during screening if no local PD-L1 test result is available. Central test result for PD-L1 will be required prior to subject enrollment. For cohort 9 subjects with local PD-L1 test result confirming CPS ≥ 1, archival or fresh tissue sample for exploratory analysis should be submitted within 5 days of enrollment.
• Subject has ECOG performance status of 0 or 1.
• Subject has the following baseline laboratory data. If a subject has received a recent blood transfusion, the hematology tests must be obtained ≥ 28 days after any blood transfusion.
• absolute neutrophil count (ANC) ≥ 1.0 × 10^9/L
• platelet count ≥ 100 × 10^9/L
• hemoglobin ≥ 9 g/dL
• serum total bilirubin ≤ 1.5 × upper limit of normal (ULN) or ≤ 3 × ULN for subjects with Gilbert's disease
• creatinine clearance (CrCl) ≥ 30 mL/min as estimated per institutional standards or as measured by 24-hour urine collection (glomerular filtration rate [GFR] can also be used instead of CrCl).
• alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 × ULN
• Subject agrees not to participate in another interventional study while receiving study treatment in the present study.
• Additional contraceptive requirements exist for male and female subjects.

  Disease Specific Inclusion Criteria:

  • Evidence of progression on or after the last regimen received.
  • Locally advanced or metastatic disease that is not amenable to curative intent treatment. Cohort 1: HR+/HER2- breast cancer
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically- or cytologically-confirmed HR+/HER2- (estrogen receptor [ER] positive and/or progesterone receptor [PR] positive, and HER2 negative) breast cancers and are not considered a candidate for further hormonal therapy. Subject will be considered HR+ if biopsies show ≥ 1% expression of ER or PR as per current American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject must have received a taxane or anthracycline in the neoadjuvant, adjuvant or incurable, locally advanced or metastatic setting.
  • Prior cytotoxic regimen received in the neoadjuvant or adjuvant setting will count as a prior cytotoxic regimen if disease recurrence occurred during or within 6 months of completing the regimen.
  • Subject has progressed, relapsed, or discontinued for toxicity during or after at least 1 prior standard of care cytotoxic regimen in the incurable, unresectable locally advanced or metastatic setting, and has not received > 2 prior lines of cytotoxic therapy in the locally advanced or metastatic setting. No limit applies to endocrine therapies. Poly(ADP-ribose) polymerases (PARP) inhibitors do not count as a line of cytotoxic therapy.
  • Subject has progressed, relapsed, or discontinued for toxicity during or after receiving endocrine therapy or with hormonally-directed therapy with cyclin-dependent kinase (CDK) inhibitors. Prior therapy with CDK inhibitors is not required. Cohort 2: triple negative breast cancer (TNBC)
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically- or cytologically-confirmed TNBC; defined as unequivocal TNBC histology (ER-negative/PR-negative/HER2-negative). This is defined by < 1% expression of ER and PR by immunohistochemistry (IHC), and that are, for HER2, either 0 to 1+ by IHC, or IHC 2+ and fluorescence in situ hybridization (FISH) negative (not amplified) as per current ASCO/CAP guidelines.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject must have received a taxane or anthracycline in the neoadjuvant, adjuvant or incurable, locally advanced or metastatic setting.
  • Prior cytotoxic regimen received in the neoadjuvant or adjuvant setting will count as a prior cytotoxic regimen if disease recurrence occurred during or within 6 months of completing the regimen.
  • Subject has progressed, relapsed, or discontinued for toxicity during or after at least 1 prior standard of care cytotoxic regimen in the incurable, unresectable locally advanced or metastatic setting, and has not received > 2 prior lines of cytotoxic therapy in the locally advanced or metastatic setting. Poly(ADP-ribose) polymerases (PARP) inhibitors do not count as a line of cytotoxic therapy.
  • Subject has received prior therapy with an anti-programmed cell death protein-1 (PD-1) or an anti-programmed cell death-ligand 1 (PD-L1) based on subject's tumor PD-1 or PD-L1 expression and local treatment guidelines and has progressed or discontinued treatment due to toxicity, or therapy is contraindicated for subject. Cohort 3: squamous non-small cell lung cancer (NSCLC)
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically or cytologically-confirmed squamous NSCLC.
  • Subjects with mixed histology NSCLC are eligible provided there is not any component of neuroendocrine histology.
  • Subjects with known epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), reactive oxygen species (ROS), BRAF, or other actionable mutations are eligible if treated with mutation targeted therapy and have progressed, relapsed, or discontinued treatment due to toxicity.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject has progressed, relapsed, or discontinued treatment due to toxicity after 1 platinum-based standard of care regimen for locally advanced or metastatic disease, and has not received > 2 prior lines of cytotoxic anticancer therapy in the locally advanced or metastatic setting. 1. Subjects with locally advanced disease who previously received curative intent treatment with platinum-based standard of care regimen in the adjuvant or neoadjuvant setting or as part of concomitant chemoradiation therapy are eligible if they have progressed or relapsed within 6 months of completion. 2. Maintenance therapy does not constitute a new chemotherapy regimen provided there was no progression after the initial platinum-based regimen. 3. Changing chemotherapy agents during platinum-based treatment for the management of toxicities does not constitute a new chemotherapy regimen provided no progression had occurred while on the initial therapy.
  • Subject has received prior therapy with an anti-PD-1 or anti-PD-L1 based on subject's tumor PD-1 or PD-L1 expression and local treatment guidelines and has progressed, relapsed, or discontinued treatment due to toxicity, or therapy is contraindicated for subject. Cohort 4: non-squamous non-small cell lung cancer
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically- or cytologically-confirmed non-squamous NSCLC.
  • Subjects with mixed histology NSCLC are eligible provided there is not any component of neuroendocrine histology.
  • Subjects with known EGFR, ALK, ROS, BRAF, or other actionable mutations are eligible if treated with mutation targeted therapy and have progressed, relapsed, or discontinued treatment due to toxicity.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject has progressed, relapsed, or discontinued treatment due to toxicity after 1 platinum-based standard of care regimen for locally advanced or metastatic disease, and has not received > 2 prior lines of cytotoxic anticancer therapy in the locally advanced or metastatic setting. 1. Subjects with locally advanced disease who previously received curative intent treatment with platinum-based standard of care regimen in the adjuvant or neoadjuvant setting or as part of concomitant chemoradiation therapy are eligible if they have progressed or relapsed within 6 months of completion. 2. Maintenance therapy does not constitute a new chemotherapy regimen provided there was no progression after the initial platinum-based regimen. 3. Changing chemotherapy agents during platinum-based treatment for the management of toxicities does not constitute a new chemotherapy regimen provided no progression has occurred while on the initial therapy.
  • Subject has received prior therapy with an anti-PD-1 or anti-PD-L1 based on subject's tumor PD-1 or PD-L1 expression and local treatment guidelines and has progressed, relapsed, or discontinued treatment due to toxicity, or therapy is contraindicated for subject. Cohort 5: second-line or later head and neck cancer
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically- or cytologically-confirmed head and neck cancer.
  • Primary tumor site must arise from the oral cavity, oropharynx, hypopharynx, and larynx; tumors arising from the nasopharynx are excluded. Salivary gland tumors and/or parotid gland tumors are not eligible for Cohort 5.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject has progressed, relapsed, or discontinued treatment due to toxicity after 1 platinum-based standard of care regimen for locally advanced or metastatic disease, and has not received > 2 prior lines of cytotoxic anticancer therapy in the locally advanced or metastatic setting.
  • Subjects with locally advanced disease who previously received curative intent treatment with platinum-based standard of care regimen in the adjuvant or neoadjuvant setting or as part of concomitant chemoradiation therapy are eligible if they have progressed or relapsed within 6 months after completion.
  • Subject has received prior therapy with an anti-PD-1 or anti-PD-L1 based on subject's tumor PD-1 or PD-L1 expression and local treatment guidelines and has progressed, relapsed, or discontinued treatment due to toxicity, or therapy is contraindicated for subject. Cohorts 6, 7 and 8: gastric or gastroesophageal junction (GEJ) or esophageal adenocarcinoma
  • Subject has evidence of radiographic progression on or after the last regimen received.
  • Subject has histologically- or cytologically-confirmed gastric, GEJ, or esophageal cancer.
  • Subject has locally advanced or metastatic disease that is not amenable to curative intent treatment.
  • Subject has progressed, relapsed, or discontinued due to toxicity after 1 platinum-based standard of care regimen for locally advanced or metastatic disease, and has not received > 2 prior lines of cytotoxic anticancer therapy in the locally advanced or metastatic setting.
  • Neoadjuvant or adjuvant cytotoxic regimens will count as a prior regimen if relapsed or progressed ≤ 6 months after completion.
  • Subject must have received a HER2 directed therapy if known to have HER2 positive cancer.
  • Subject has received prior therapy with an anti-PD-1 or anti-PD-L1 based on subject's tumor PD-1 or PD-L1 expression and local treatment guidelines and has progressed, relapsed, or discontinued treatment due to toxicity, or therapy is contraindicated for subject. Cohort 9: 1L HNSCC
  • Subject has histologically- or cytologically-confirmed head and neck squamous cell carcinoma. a. Primary tumor site must arise from the oral cavity, oropharynx, hypopharynx, and larynx; tumors arising from the nasopharynx are excluded. Salivary gland tumors and/or parotid gland tumors are not eligible for Cohort 9.
  • Subject has recurrent or metastatic disease that is incurable by local therapies.
  • Subject's tumor sample has PD-L1 combined positive score (CPS) of ≥ 1 as determined by local or central IHC testing.
  • Subject has had no prior systemic therapy administered in the recurrent or metastatic setting (with the exception of systemic therapy completed > 6 months prior if given as part of multimodal treatment for locally advanced disease). Subjects who have received a PD-1 or PD-L1 inhibitor in the curative setting are eligible if it has been at least 12 months since last dose of the anti PD-L1 agent.
  • Subject has ANC ≥ 1.5 × 10^9/L.
  • International normalized ratio (INR) OR prothrombin time (PT) and activated partial thromboplastin (aPTT) both ≤ 1.5 × ULN unless subject is receiving anticoagulant therapy as long as PT or aPTT is within the therapeutic range of intended use of anticoagulants. PTT may be used if local lab is unable to perform aPTT.
  • For subjects with oropharynx tumors, subject has results from testing of HPV status by p16 testing.

  Exclusion Criteria:

  For All Cohorts:
  • Subject has preexisting sensory or motor neuropathy Grade ≥ 2.
  • Subject has active central nervous system (CNS) metastases. Subjects with treated CNS metastases are permitted on study if all the following are true:
  • CNS metastases have been clinically stable for ≥ 6 weeks prior to screening
  • If requiring steroid treatment for CNS metastases, the subject is on a stable dose ≤ 20 mg/day of prednisone or equivalent for ≥ 2 weeks
  • Baseline imaging scans show no evidence of new or enlarged brain metastasis
  • Subject does not have leptomeningeal disease
  • Subject has ongoing clinically significant toxicity (Grade 2 or higher with the exception of alopecia) associated with prior treatment (including systemic therapy, radiotherapy or surgery).
  • Subjects with ongoing ≥ Grade 3 immunotherapy-related hypothyroidism or panhypopituitarism are excluded. Subjects with ongoing immunotherapy-related colitis, uveitis, myocarditis or pneumonitis, or subjects with other immunotherapy-related AEs requiring high doses of steroids (> 20 mg/day of prednisone or equivalent), are excluded. Subject with ≤ Grade 2 immunotherapy-related hypothyroidism or panhypopituitarism may be enrolled when well maintained/controlled on a stable dose of hormone replacement therapy (if indicated).
  • Subject has a history of uncontrolled diabetes mellitus within 3 months before the first dose of study treatment. Uncontrolled diabetes (within 3 months before first dose) is defined as hemoglobin A1c (HbA1c) ≥ 8% or HbA1c between 7 and < 8% with associated diabetes symptoms (polyuria or polydipsia) that are not otherwise explained. The lowest HbA1c during the screening period will be used to determine eligibility.
  • Subject has prior treatment with enfortumab vedotin or other monomethyl auristatin E (MMAE) based antibody-drug conjugates (ADCs).
  • Subject has a second malignancy diagnosed within 3 years before first dose of study drug, or any evidence of residual disease from a previously diagnosed malignancy. Subjects with non-melanoma skin cancer, localized prostate cancer treated with curative intent with no evidence of progression, low-risk or very low-risk (per standard guidelines) localized prostate cancer under active surveillance/watchful waiting without intent to treat, or carcinoma in situ of any type (if complete resection was performed) are allowed.
  • Subject is currently receiving systemic antimicrobial treatment for viral, bacterial, or fungal infection at the time of first dose of study treatment. Routine antimicrobial prophylaxis is permitted.
  • Subject has known active hepatitis B (e.g., hepatitis B surface antigen [HBsAg] reactive) or active hepatitis C (e.g., hepatitis C virus [HCV] RNA [qualitative] is detected).
  • Subject has known history of human immunodeficiency virus (HIV) infection (HIV 1 or 2).
  • Subject has documented history of a cerebral vascular event (stroke or transient ischemic attack), unstable angina, myocardial infarction or cardiac symptoms (including congestive heart failure) consistent with New York Heart Association Class III-IV within 6 months prior to the first dose of study drug.
  • Subject has major surgery within 4 weeks prior to first dose of study drug.
  • Subject had radiotherapy, chemotherapy, biologics, investigational agents, and/or antitumor treatment with immunotherapy that is not completed 2 weeks prior to first dose of study drug.
  • Subject has known hypersensitivity to enfortumab vedotin or to any excipient contained in the drug formulation of enfortumab vedotin (including histidine, trehalose dihydrate and polysorbate 20) OR subject has known hypersensitivity to biopharmaceutical produced in Chinese hamster ovary cells.
  • Subject has known active keratitis or corneal ulcerations. Subject with superficial punctate keratitis is allowed if the disorder is being adequately treated.
  • Subject has any condition which makes the subject unsuitable for study participation. Cohort 9: 1L HNSCC
  • Had PD within 6 months of completion of curatively intended systematic treatment for locoregionally advanced HNSCC.
  • Has had an allogeneic tissue/solid organ transplant. Has severe hypersensitivity (≥grade 3) to pembrolizumab and/or any of its excipients.
  • Has a history of (non-infectious) pneumonitis / interstitial lung disease that required steroids or has current pneumonitis / interstitial lung disease.
  • Has a history of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced pneumonitis, idiopathic pneumonitis, or evidence of active pneumonitis on screening chest CT scan.
  • Has a life expectancy of less than 3 months and/or has rapidly progressing disease (e.g. tumor bleeding, uncontrolled tumor pain) in the opinion of the treating investigator.
  • Active autoimmune disease that has required systemic treatment in past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). 1. Replacement therapy (e.g., thyroxine, insulin, physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency) is not considered a form of systemic treatment and is allowed. 2. Brief (<7 days) use of systemic corticosteroids is allowed when use is considered standard of care. 3. Subjects with vitiligo, psoriasis, type 1 diabetes mellitus, hypothyroidism, or resolved childhood asthma/atopy will not be excluded. 4. Subjects requiring intermittent use of bronchodilators, inhaled steroids, or local steroid injections will not be excluded. 5. Subjects with hypothyroidism that is stable with hormone replacement or Sjögren's syndrome will not be excluded.
  • Has an active infection requiring systemic therapy.
  • Has received prior therapy with an anti-PD-1 or anti-PD-L1 agent in the recurrent/metastatic setting. If anti-PD-1 or anti-PD-L1 agent was given as part of curative intent therapy, it must be at least 1 year since last dose.
  • Has received a live vaccine within 30 days of planned start of study therapy. Examples of live vaccines include, but are not limited to, the following: measles, mumps, rubella, varicella/zoster (chicken pox), yellow fever, rabies, Bacillus Calmette Guérin, and typhoid vaccine. Seasonal influenza vaccines for injection are generally killed virus vaccines and are allowed; however, intranasal influenza vaccines (e.g., FluMist®) are live attenuated vaccines and are not allowed.
  • Subject has active tuberculosis

Inclusion Criteria

• Male or female, aged >=18 years at the time of informed consent.
• Metastatic or unresectable BC that is histologically confirmed to be either HER2-positive (defined as an immunohistochemistry [IHC] status of 3+, or a positive in situ hybridization [ISH] test [fluorescence, chromogenic, or silver-enhanced ISH] if IHC status is 2+) or HER2-low (defined as an IHC status of 1+, or 2+ and negative ISH) per the American Society of Clinical Oncology/College of American Pathology guidelines as documented at the time of trastuzumab deruxtecan (T-DXd) treatment.
• Must have previously received T-DXd.
• Sufficient tumor tissue is required for HER2 status testing at a central laboratory.
• Measurable disease per RECIST 1.1 as assessed by the investigator. Participants with bone only disease may be eligible if there is a measurable soft tissue component associated with the bone lesion.
• Must have previously received at least 1 but no more than 3 prior chemotherapy-based regimes in the unresectable or metastatic setting. If recurrence occurred within 6 months of (neo)adjuvant chemotherapy, this would count as 1 line of chemotherapy.
• If HR-positive HER2-low BC, must have previously received endocrine therapy and is not expected to benefit from further endocrine therapy.
• ECOG PS 0 or 1.
• Life expectancy of at least 3 months.
• Adequate organ function and laboratory parameters.

Exclusion Criteria

• Inflammatory BC.
• Presence of brain or subdural metastases, unless participants has completed local therapy and has discontinued the use of corticosteroids for this indication for at least 4 weeks prior to starting treatment in this study.
• Diagnosed with meningeal carcinomatosis.
• Presence of malignant effusion/ascites requiring drainage for symptom relief.
• Received anticancer therapy (chemotherapy or other systemic anticancer therapies, immunotherapy, radiation therapy, etc) or an investigational drug or device within the past 28 days or 5 half-lives, whichever is shorter.
• Prior treatment with eribulin.
• Any prior hypersensitivity to monoclonal antibodies or contraindication to the receipt of corticosteroids or any of the excipients (investigators should refer to the prescribing information for the selected corticosteroid).
• Residual toxic effects of prior therapies or surgical procedures that is Grade >=2 (except alopecia or anemia).
• Grade >=2 peripheral neuropathy or history of Grade >=3 peripheral neuropathy or discontinued any prior treatment due to peripheral neuropathy.
• Active pneumonitis/interstitial lung disease (ILD) (including asymptomatic Grade 1) or any clinically significant lung disease (example, chronic obstructive pulmonary disease), history of pneumonitis/ILD that required systemic steroids, or received radiotherapy to lung fields within 12 months of Cycle 1 Day 1 of study treatment.
• Congestive heart failure greater than New York Heart Association Class II or left ventricular ejection fraction (LVEF) <50% measured by multigated acquisition scan (MUGA) or echocardiogram.
• Has a corrected QT interval prolongation per Fridericia formula (QTcF) greater than (>) 470 millisecond (ms) (for both males and females) based on screening triplicate 12-lead ECG.
• Concomitant active infection requiring systemic treatment, except:
• If known to be human immunodeficiency virus (HIV)-positive, must be on anti-HIV therapy for at least 4 weeks and have a clusters of differentiation 4+ T-cell (CD4+) count >=350 cells per microliter (cells/mcL) and an HIV viral load less than 400 copies per milliliter (copies/mL).
• If meets the criteria for anti-hepatitis B virus (HBV) therapy, must agree to take anti-HBV therapy, if known to be HBV-positive as defined by positive hepatitis B surface antigen or hepatitis B core antibody. HBV viral load must be undetectable.
• If known to be hepatitis C virus (HCV)-positive must have completed curative therapy for HCV. HCV viral load must be undetectable.
• Known history of active bacillus tuberculosis (TB).
• Any medical or other condition which, in the opinion of the investigator would preclude the participant's participation in the clinical study.