Table 1.

Comparison of ADC and Recombinant Immunotoxin Therapeutics

	ADC	Immunotoxin
Targeting moiety	Full monoclonal antibody	Antibody fragment
Payload	Chemotherapy drug	Bacterial or plant toxin
Mechanism of Action	Most commonly anti-tubulin agents	Protein synthesis inhibition
Toxicity	Target specific, and most commonly peripheral neuropathy, myelosuppression	Target specific and vascular leak syndrome
Approved drugs in class	Trastuzumab emtansine (for HER-2 positive breast cancer); Brentuximab vedotin (for Hodgkins lymphoma and systemic anaplastic large cell lymphoma)	Denileukin diftitox (for cutaneous T cell lymphoma)
Advantages	Demonstrated efficacy in refractory setting Better tolerated than most standard chemotherapy Can kill tumor cells that don’t express target through bystander effect	Can kill quiescent and rapidly dividing cells as a single agent Ideal for combination with standard chemotherapy due to non-overlapping mechanism of action and toxicity profile No off-target toxicity from bystander effect
Disadvantages	Overlapping mechanism of action to standard chemotherapy Cumulative peripheral neuropathy	Immunogenicity Target selection more restrictive since payload is effective against many quiescent normal cells