The goal of this clinical trial is to learn if Gemcitabine, a chemotherapy drug that is usually used to treat breast cancer after other treatments have failed, is better at treating triple negative breast cancer in Black Caribbean women than Paclitaxel, one of the chemotherapy drugs that is usually used first. People will be invited to participate in the trial if they are Caribbean women of African ancestry, are 18 years or older, have had a biopsy that shows that they have triple negative breast cancer (TNBC), and are willing to take part.

The main questions the trial aims to answer are:

1. Does Gemcitabine stop triple negative breast cancer from growing or spreading better than Paclitaxel?
2. Are participants more likely to get better when taking Gemcitabine or Paclitaxel?
3. What medical problems do participants have when taking Gemcitabine for breast cancer?
4. Do Gemcitabine and Paclitaxel affect Black Caribbean women differently than women from other regions or ethnic groups?

To answer these questions, half of participants will be treated with Gemcitabine while half is treated with Paclitaxel. Both drugs are given by injection and have already been approved for breast cancer treatment. Participants will:

• Take Gemcitabine for two weeks followed by a two-week break, or take Paclitaxel once a week for the same time period.
• Have some of the cancer tissue that was tested from their biopsy taken for more testing.
• Have a physical exam and a blood test done every 3 weeks.
• Have images of their cancer taken using CT (Computed Tomography) or MRI (Magnetic Resonance Imaging) every 6 weeks.
• Answer a brief questionnaire about how they are feeling every 8 weeks.
• Be checked on every month after treatment is finished to make sure the cancer hasn't come back.

This is a Phase II, randomized, open-label, multicentre clinical trial evaluating the second-line chemotherapy drug Gemcitabine compared with standard-of-care Paclitaxel as first-line treatment for Caribbean women of African ancestry with metastatic triple-negative breast cancer (TNBC).

Eligible participants will be randomized in a 1:1 ratio to one of two treatment arms, stratified by study site (5 major hospitals in Jamaica, Barbados and Trinidad and Tobago). Treatment will continue until disease progression, unacceptable toxicity, withdrawal of consent, or investigator decision.

Participants assigned to the investigational arm will receive Gemcitabine administered on days 1 and 8 of a 21-day cycle. Participants assigned to the control arm will receive Paclitaxel administered weekly according to institutional standard practice.

Tumour assessments- via MRI (Magnetic Resonance Imaging) or CT (Computed Tomography) as appropriate- will be conducted at regular intervals to evaluate disease status. Safety assessments (blood test panels) will occur throughout the study, and patient-reported outcomes will be collected using validated quality-of-life instruments.

Participants will be followed for progression, adverse events and survival outcomes for up to 12 months following treatment initiation. Data will be collected and managed using a secure, HIPAA-compliant electronic data capture system in compliance with HIPAA (Health Insurance Portability and Accountability Act). All analyses will be conducted using de-identified data.

Inclusion Criteria:

1. Self-identified Caribbean Black women of Jamaican, Trinidadian, or Barbadian ancestry
2. Age ≥18 years
3. Histologically confirmed metastatic triple-negative breast cancer (recent biopsy required)
4. ECOG (Eastern Cooperative Oncology Group) performance status 0-1
5. No prior systemic therapy for metastatic disease
6. Adequate organ function (detailed laboratory criteria specified)
7. Written informed consent
8. Willingness to provide biospecimens for research

Exclusion Criteria:

1. Prior gemcitabine, anthracycline, or taxane treatment in any setting
2. Active brain metastases requiring immediate treatment
3. Pregnant or breastfeeding
4. Concurrent participation in other interventional trials
5. Medical conditions precluding safe chemotherapy administration
6. Inability to provide informed consent

De-identified individual participant data will be made available after the conclusion of the study to researchers with approved proposals via email request. Data sharing will require a signed data use agreement and be determined on a case-by-case basis.

Beginning after publication of primary results and available for at least 5 years.

Access will be provided to researchers with methodologically sound proposals, subject to approval by the study investigators and execution of a data use agreement.