SLC39A6 and breast cancer: Beyond HER2 and TROP2, alternative targets being evaluated for novel breast cancer ADCs in phase I‐II trials include HER3 [55, 56, 57], B7‐H3 [58], B7‐H4 [59, 60], CD166 [61], folate receptor‐α [62], LIV‐1 [63, 64, 65, 66], nectin‐4 [67], ROR1 (NCT04504916), and ROR2 (NCT03504488).