Dozens of drugmakers are conducting human trials for a record 89 therapies that pair antibodies with toxic agents to fight cancer, evidence of renewed confidence in an approach that has long fallen short of its promise.

Axar.az reports citing Reuters that these antibody-drug conjugates, or ADCs, from companies including AstraZeneca and GlaxoSmithKline, are described by researchers as “guided missiles” packing a powerful anti-cancer punch.

They are engineered to zero in on tumors and then release cytotoxins that deliver up to 10,000 times the potency of standard chemotherapy, while minimizing damage to healthy tissue.

The approach has for decades been a major biotech industry focus. Many experimental ADCs, however, failed due to the complexity of pairing the right antibody with the appropriate toxic agent. Some were abandoned as too weak; others were too harmful.