DB-1305/BNT325 is an investigational antibody-drug conjugate (ADC) designed to target TROP-2, a protein commonly found on triple-negative breast cancer (TNBC) cells. Once attached, it delivers a topoisomerase-1 inhibitor to help kill the cancer. Each antibody carries about four drug molecules.
This treatment is being tested in a Phase 1/2 study in patients with metastatic TNBC who have already tried multiple treatments. In the first group of 26 patients, most had previously received at least two other therapies. Even in this heavily pretreated population, the early results were encouraging. About 34.6% of patients had their tumors shrink, and around 80.8% experienced some control of their disease. On average, the cancer did not worsen for about 5.5 months.
Side effects were common but mostly manageable. All patients experienced treatment-related side effects, and about one-third had more serious reactions. The most frequent problem was mouth inflammation (stomatitis), usually mild or moderate, similar to what is seen with another TROP-2 ADC, datopotamab deruxtecan. Other common issues included anemia and low levels of white blood cells. Only one patient stopped treatment because of side effects, showing that the drug was generally tolerable.
Because of these positive early findings, researchers plan to continue studying DB-1305/BNT325. Ongoing testing includes combining it with pumitamig, a drug that targets both VEGF and PD-L1, reflecting the growing interest in pairing ADCs with immunotherapies to improve treatment results in breast cancer.