Prototype DAA/TAA Vaccine Targeting MUC1 for Immune Interception and Prevention in Ductal Carcinoma In Situ

This trial is testing a new vaccine designed to train the immune system to recognize and potentially eliminate ductal carcinoma in situ (DCIS) — a very early, non-invasive form of breast cancer — before it can progress. The vaccine targets a protein called MUC1 that is abnormally expressed on DCIS cells. **You may be eligible if...** - You are a woman 18 or older with a confirmed biopsy diagnosis of estrogen receptor-positive (ER+) DCIS at least 1 cm in size - You are planning to have surgery as part of your treatment - You are a candidate for hormone-blocking medications (SERMs or aromatase inhibitors) - Your blood counts and organ function are within acceptable ranges **You may NOT be eligible if...** - Your biopsy showed invasive breast cancer greater than 1 mm - You have had another cancer within the past 5 years (some exceptions apply) - You are currently on hormone replacement therapy or related medications without a 30-day washout period - You have had a prior DCIS in the same breast - You are on immunosuppressive medications or have an active autoimmune disease - You are pregnant or pre-menopausal without adequate contraception Talk to your doctor to see if this trial is right for you.