A Ph II Study of the TheraBionic P1 Device in Subjects With Hormone Positive Breast Cancer

Inclusion Criteria: * Participant must have locally advanced/unresectable or metastatic Hormone Receptor (HR) positive, Human Epidermal growth factor receptor 2 (HER2) negative breast cancer as defined by the 2010 American Society of Clinical Oncology (ASCO) College of American Pathologists (CAP) guidelines (estrogen receptor \[ER\] and/or progesterone receptor \[PR\] \>1% and HER2 negative by immunohistochemistry \[IHC\] and/or fluorescent in situ hybridization \[FISH\]). * Participant must have received and progressed on or are intolerant to all therapies known to confer overall survival benefit, including at least one line of endocrine + CDK4/6 inhibitor therapy AND one line of cytotoxic such as chemotherapy and/or antibody drug conjugates (ADCs). * Participant must be a woman ≥ 22 years old and must be able to understand and sign an informed consent form. * Participant must have a life expectancy of at least 3 months. * Participant must have an Eastern Cooperative Oncology Group (ECOG) performance score of 0-2. * it is not known what effects this treatment has on human pregnancy or development of the embryo or fetus. Therefore, women of childbearing potential must agree to avoid becoming pregnant starting at initiation of treatment up until at least 30 days after the last TheraBionic P1 session. * Participants must meet one of the following: * Surgically sterile (hysterectomy, bilateral oophorectomy, or bilateral salpingectomy) * Post-menopausal, defined as no menses for at least 12 months prior to the screening visit without alternative medical causation. * Agree to practice true abstinence when this is in line with the preferred and usual lifestyle of the participant. Periodic abstinence methods such as calendar, ovulation, symptothermal, or post ovulation tracking are not acceptable. * Not in a sexual relationship in which they may become pregnant (i.e. same-sex relationship) * If they are of childbearing potential, agree to use at least one method of contraception. Withdrawal is not an acceptable contraceptive method. Exclusion Criteria: * Participants with known active secondary malignancy, unless, in the opinion of the investigator, it is unlikely to interfere with the safety and efficacy of the endpoints * Participants that are taking any other investigational drugs. * Participants that are pregnant or breastfeeding. If a breastfeeding participant would like to be part of this study, breastfeeding must be discontinued. * Participants with active oral mucosal inflammation, ulceration, or other pathology that could interfere with the use of TheraBionic P1 device (for example: mucositis, thrush, bleeding mucosal lesions, oral herpes, aphthous stomatitis, mouth ulcers, chancre sores, gingivostomatitis, herpangina, aphthae). * Participants receiving calcium channel blockers and any agent blocking L-type or T-type voltage gated calcium channels (for example: amlodipine, nifedipine, ethosuximide, ascorbic acid/vitamin C, etc.) unless their medical treatment is discontinued at least one day prior to treatment. Participant must agree to abstain from using calcium channel blockers for the duration of treatment on study. * Participants that do not agree to be followed according to the study protocol or have cognitive or physical inability to use the device.