PTK7 and neoplasm: Research has extended further to sort additional potential targets other than tumor-associated antigens, and proteins produced in the tumor microenvironment (e.g., CD25, CD205, and B7-H3) or by cancer stem cells (e.g., DLL3, ephrin-A4, PTK7, and 5T4) have shown promise for which particular ADCs are in clinical trials (81).