Calicheamicin

Ladror D, et al. Drug Metabolism and Disposition, 2024, 52(2), 135-142.

Calicheamicin, an enediyne antibiotic with extreme cytotoxicity, is a validated payload in antibody-drug conjugates (ADCs). The preclinical evaluation of ABBV-011, an SEZ6-targeted calicheamicin ADC, focused on experimental characterization of catabolic stability. Researchers employed in vitro plasma incubation assays combined with HPLC-MS analytical profiling to identify circulating metabolites and catabolites. Comparative metabolic studies against gemtuzumab ozogamicin and inotuzumab ozogamicin revealed a novel liability: disulfide bond cleavage in the N-acetyl-γ-calicheamicin payload, compromising linker stability. This was further supported by in vivo pharmacokinetic experiments, which confirmed similar degradation pathways. These experimental insights emphasize the importance of systematic catabolic pathway analysis to optimize linker design and predict ADC performance. ABBV-011 exemplifies how targeted metabolism studies of calicheamicin conjugates inform rational ADC development.

DuPont M, et al. International Journal of Pharmaceutics, 2024, 654, 123954.

Calicheamicin was experimentally applied through conjugation with a pH Low Insertion Peptide (pHLIP) to achieve tumor-selective delivery. A reduced calicheamicin derivative was covalently linked to a single cysteine at the membrane-inserting terminus of pHLIP. Upon insertion into cellular membranes under acidic tumor microenvironments, cytoplasmic disulfide reduction triggered release of the active drug. Experimental validation included interaction studies with liposomal and cellular membranes, demonstrating effective DNA strand cleavage and cytotoxicity in proliferative cancer cells and non-proliferative M2 macrophages. In vivo murine models showed significant tumor growth inhibition without systemic toxicity. Biodistribution analyses confirmed selective intratumoral accumulation, particularly at tumor-stroma interfaces, with concomitant depletion of CD206⁺ tumor-associated macrophages, highlighting the therapeutic potential of pHLIP-calicheamicin conjugates.