Next-generation antibody-drug conjugates (ADCs) comprising an affinity-matured version of ABT-806 conjugated to either monomethyl auristatin E (ABBV-221) [13] or the ultra-potent pyrrolobenzodiazepine (PBD) dimer (ABBV-321) [14] exhibit enhanced EGFR affinities and killing potencies and have demonstrated effectiveness within EGFR-expressing tumors or tumor cell lines. Here, EGFR is linked to neoplasm.