A Phase 1, Multicenter, Open-label, First-in-Human Study of ITI-5000 (Self-Amplifying RNA Vaccine) Alone and in Combination With Pembrolizumab in Participants With Stage II-III Triple-Negative Breast Cancer (TNBC) Who Have Completed Standard Curative Intent Therapy (VITAL-TNBC Study)
This study tests an investigational cancer vaccine called ITI-5000 in people who have completed standard treatment for early-stage triple-negative breast cancer (TNBC). ITI-5000 is a self-amplifying RNA (saRNA) vaccine that instructs the immune system to recognize and attack cancer cells expressing two proteins found on TNBC cells-HERV-K and CT83-fused with a molecule called LAMP-1 that helps the immune system respond more strongly. The vaccine is delivered inside lipid nanoparticles (LNPs), similar to other approved mRNA vaccines. The study has two parts: * Part A: Participants receive ITI-5000 alone at one of two dose levels (1 µg or 10 µg), given as an injection into the upper arm muscle every 28 days for 3 doses total. The goal is to find the safest dose. * Part B: Participants receive ITI-5000 at the best dose identified in Part A, combined with an approved immunotherapy drug called pembrolizumab (Keytruda®), every 21 days for 3 doses total.
• Age: Adults aged 18 years or over.
• Consent: Provided a signed and dated informed consent form (ICF).
• Diagnosis: Histologically confirmed stage 2-3 triple-negative breast cancer (TNBC), defined as HER2-negative, ER-negative, and PgR-negative by immunohistochemistry. BRCA mutations are allowed.
• Prior Treatment: Completed all planned standard therapy (surgery, chemotherapy, radiation, and/or pembrolizumab as applicable) and be within 36 months of definitive surgery.
• Performance Status: ECOG performance status of 0 or 1.
• Organ Function: Adequate organ function at baseline (hematology, biochemistry, etc.).
• Cardiac Function: No significant ischemic heart disease or myocardial infarction within 3 months before vaccination #1; QTc ≤470 msec for females or ≤450 msec for males.
• Pregnancy: Women of childbearing potential must have a negative serum pregnancy test within 3 days before vaccination #1 and agree to use highly effective contraception during the study and for 123 (Part A) or 137 (Part B) days after last study drug.
• Compliance: Able to attend required study visits and follow-up.
• Understanding: Able to understand and provide signed informed consent per IRB/IEC guidelines.
• Vaccinations: Agrees not to receive routine vaccinations until at least 30 days after the last study vaccine.
• Alternative Therapies: Agrees not to use alternative therapies from the time of informed consent through 30 days following vaccination #3.