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Molecular Templates has created vast libraries of ETBs. Each ETB has a distinct binding affinity but retains the biologically active properties of the parent toxin.  ETBs are capable of targeting validated therapeutic cell surface receptors but also non-traditional targets that cannot be therapeutically targeted by antibodies or small molecules.  

Molecular Templates is developing a number of lead ETB candidates against a variety of validated and novel cancer targets. These lead ETBs range from IND enabling to early preclinical characterization stages of development.

	Antibodies	Immunotoxins	ETBs
Screening Metric	Binding affinity	Binding affinity of targeting domain	Direct cell-kill  [a]
Target ID a priori	Required	Required	Not required  [b]
Mechanism of Action	Target binding	Direct cell-kill	Direct cell-kill
Target Specificity	Very high (nM to pM)	High (nM)	High (nM)   [c]
Size	~150 kd	~60 kd	~20kd
Half-Life	Days to weeks	Minutes to days	Minutes to days   [d]
PK/PD	Established	Established	Established   [e]
Other Scaffold Properties	Receptor mediated internalization	Forced internalization; Intracellular routing	Forced internalization; Intracellular routing; Antigen presentation

[a]  ETBs are screened on cell-killing ability that involves its ability to bind a target, internalize, and route itself intracellularly.
[b]  Because ETBs are selected on cell-kill, etiology based screens can be performed without knowing the target beforehand.
[c]   A different standard applies to ETBs given their unique features and high affinity does not correlate to cell kill specificity or potency.
[d]   ETBs can be manipulated to extend half life in the event it is optimal for particular disease indications.
[e]   ETBs share the same pharmcokinetic and pharmacodyanmics as the parent toxin scaffold making them predictable.

©2010 Molecular Templates Inc.