Ansamitocin P-3 is primarily used as a cytotoxic agent in the development of antibody-drug conjugates (ADCs) for targeted cancer therapy. Its high potency in inhibiting microtubule assembly makes it effective in killing cancer cells at low concentrations. Due to its mechanism of action—disrupting mitotic division—it is especially valuable when linked to monoclonal antibodies that deliver the compound selectively to tumor cells, minimizing damage to healthy tissues. This targeted approach has been applied in the treatment of various cancers, including breast and hematological malignancies. Its role as a payload in ADCs continues to be explored in clinical and preclinical studies, contributing to advancements in precision oncology.