Discontinuation of Maintenance HER-2 Directed Therapy in Long-Term Survivors of Metastatic HER-2 Positive Breast Cancer

This study is examining whether it is safe to stop HER2-targeted maintenance therapy in people with HER2-positive stage IV breast cancer who have been in complete remission for at least 3 years and show no signs of cancer in their blood (no circulating tumor DNA). The goal is to find out if some patients can safely take a treatment break without the cancer coming back. **You may be eligible if...** - You are 18 or older with HER2-positive metastatic (stage IV) breast cancer in complete radiological remission - You have been on the same anti-HER2 therapy for at least 36 months - You have no detectable circulating tumor DNA (ctDNA) in your blood, confirmed by the Signatera test - Your disease has been stable (including any brain metastases) for at least 36 months **You may NOT be eligible if...** - Your cancer is not in remission or has been controlled for less than 36 months - You have detectable circulating tumor DNA in your blood - You are currently being treated for a second cancer (other than certain skin cancers) - You have impaired decision-making capacity Talk to your doctor to see if this trial is right for you.