CX-2029 (ABBV-2029), a special ADC against CD71 (transferrin receptor 1), also defined as a Probody drug conjugate (PDC), is now being tested in phase II clinical trials to treat solid tumors, head and neck cancer, non-small-cell lung cancer, pancreatic cancer and diffuse large B-cell lymphoma [8]. Here, TFRC is linked to head and neck cancer.