The goal of this trial is to see if active surveillance monitoring and hormonal therapy in
patients diagnosed with ductal cell carcinoma in situ (DCIS), an early stage of breast
cancer, can be an effective management of the disease.

Participants will be asked to receive control hormonal therapy or an investigational hormonal
therapy treatment. Participants will be asked to return for evaluation with MRI at three
months and six months. Depending on the evaluation participants will have the option to
continue on the treatment. If the evaluation suggests surgery is recommended, the participant
will discontinue the study treatment and will undergo surgery. In addition to the treatment
and MRI evaluation, participants will be asked to provide blood sample to understand their
immune status, provide saliva sample for genetic testing, provide the study with a portion of
the tissue or slides generated from tissue removed during surgery performed as part of their
standard of care.

This open-label research study is studying (Z)-endoxifen as a possible treatment for
pre-menopausal (still having periods) women with ER+/HER2- breast cancer. (Z)-endoxifen is a
selective estrogen receptor modulator or "SERM." SERMs work to treat cancer by blocking the
body's natural estrogen from binding to cancer cells. This study includes a pharmacokinetic
part (PK, how the drug works in your body) and a treatment part. The primary purpose of the
study is to see how (Z)-endoxifen works on tumor cell growth by monitoring a cancer marker
called Ki-67. Ki-67 will be measured by biopsy of the breast after about 4 weeks of
treatment. If your cancer is responding to treatment based on the Ki-67 results, you may
continue treatment up to 24 weeks or until surgery.

The PK part of the study will be enrolled first, enrolling about 18 study participants who
will all receive oral once daily (Z)-endoxifen treatment. 12 of these participants will be
randomly assigned to treatment with an equal (50/50) chance to be assigned to (Z)-endoxifen
or (Z)-endoxifen + goserelin (a medication given to block the ovaries from making estrogen
and is also called ovarian suppression). This part of the study will help select the dose of
(Z)-endoxifen to use in the treatment part by measuring the levels of (Z)-endoxifen in the
blood stream and determine how long it takes for the body to remove it.

About 160 study participants will be enrolled in the treatment part. The treatment part will
help to determine how oral once daily (Z)-endoxifen, when taken by itself, compares to oral
once daily exemestane (a medication that decreases the amount of estrogen in the body, also
known as an aromatase inhibitor) and monthly injections of goserelin. Exemestane and
goserelin taken together is a standard treatment regimen for premenopausal patients with
ER+/HER2- breast cancer. Study participants are randomly assigned to treatment with an equal
(50/50) chance to be assigned to (Z)-endoxifen or standard treatment.

Study participation is up to 24 weeks of treatment followed by surgery.

This phase II trial compares the effect of capecitabine to endocrine therapy in patients with non-Luminal A hormone receptor-positive breast cancer that has spread from where it first started (primary site) to other places in the body (metastatic). In this study, patients submit a sample of tumor for testing to determine if their breast cancer is considered non-Luminal A. Only patients with non-Luminal A receive study treatment. In the future, doctors hope that this test can assist in picking the best treatment for patients with this type of cancer. Capecitabine is in a class of medications called antimetabolites. It is taken up by tumor cells and breaks down into fluorouracil, a substance that kills tumor cells. Endocrine therapy is treatment that adds, blocks, or removes hormones. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body's natural hormones. Giving capecitabine as compared to endocrine therapy may kill more tumor cells in patients with metastatic breast cancer.

This is an umbrella study evaluating the efficacy and safety of multiple treatment
combinations in participants with metastatic or inoperable locally advanced breast cancer.

The study will be performed in two stages. During Stage 1, four cohorts will be enrolled in
parallel in this study:

Cohort 1 will consist of Programmed death-ligand 1 (PD-L1)-positive participants who have
received no prior systemic therapy for metastatic or inoperable locally advanced
triple-negative breast cancer (TNBC) (first-line [1L] PD-L1+ cohort).

Cohort 2 will consist of participants who had disease progression during or following 1L
treatment with chemotherapy for metastatic or inoperable locally-advanced TNBC and have not
received cancer immunotherapy (CIT) (second-line [2L] CIT-naive cohort).

Cohort 3 will consist of participants with locally-advanced or metastatic HR+, HER2-negative
disease with PIK3CA mutation who may or may not have had disease progression during or
following previous lines of treatment for metastatic disease (HR+cohort).

Cohort 4 will consist of participants with locally-advanced or metastatic HER2+ /HER2-low
disease with PIK3CA mutation who had disease progression on standard-of-care therapies (HER2+
/HER2-low cohort).

In each cohort, eligible participants will initially be assigned to one of several treatment
arms (Stage 1). In addition, participants in the 2L CIT-nave cohort who experience disease
progression, loss of clinical benefit, or unacceptable toxicity during Stage 1 may be
eligible to continue treatment with a different treatment combination (Stage 2), provided
Stage 2 is open for enrollment.

This phase II trial studies the effect of hormonal therapy given after (adjuvant) combination pertuzumab/trastuzumab in treating patients with hormone receptor positive, HER2 positive breast cancer. The drugs trastuzumab and pertuzumab are both monoclonal antibodies, which are disease-fighting proteins made by cloned immune cells. Estrogen can cause the growth of breast cancer cells. Hormonal therapy, such as letrozole, anastrozole, exemestane, and tamoxifen, block the use of estrogen by the tumor cells. Giving hormonal therapy after pertuzumab and trastuzumab may kill any remaining tumor cells in patients with breast cancer.

This phase III trial compares the effect of radiation therapy combined with hormonal therapy versus hormonal therapy alone in treating patients with low risk, early stage breast cancer with Oncotype Dx Recurrence =< 18. Oncotype DX is a laboratory test which results in a score that is used to help predict whether breast cancer will spread to other parts of the body or come back. Radiation therapy uses high doses of radiation to kill cancer cells and shrink tumors but may result in some side effects. Hormones called estrogen and progesterone may contribute to the growth of breast tumor cells. Hormone therapy, also called endocrine therapy, may stop the growth of tumor cells by blocking or removing these hormones. This clinical trial may help researchers understand if patients with low-risk, early stage breast cancer who have Oncotype recurrence score of =< 18 can safely omit radiation therapy and only be treated with hormonal therapy without losing any radiation treatment benefit.