Table II:

Model Parameters

Parameter	Value	Unit	Description	Reference
CLTT	1.74 × 10−9	L/s	Total antibody clearance	Estimated (13)
CL2	2.31 × 10−8	L/s	Antibody clearance for compartment 2	Estimated (13)
CLDEC	1.74 × 10−9	L/s	Deconjugation rate	Estimated (12)
V1	1.2 × 10−3	L	Volume central compartment	Estimated (13)
V2	1.5 × 10−3	L	Volume peripheral compartment	Estimated (13)
kon	7.1 × 105	M−1s−1	T-DM1 binding rate constant	(18)
Kd	0.5	nM	T-DM1 dissociation constant	(18)
koff	3.5 × 10−4	s−1	T-DM1 dissociation rate constant	(18)
ke	3.3 × 10−5	s−1	Internalization rate constant	(19)
kdeg	8 × 10−6	s−1	T-DM1 lysosomal degradation rate constant	(20)
kloss	3.94 × 10−5	s−1	Cytotoxin loss rate constant	Estimated (21)
DAR	3.5	-	DM1 to antibody ratio	(22)
Rs	2.75 × 10−11	M/s	Target synthesis	(14)
HER2o*	5 × 104-2 × 106	receptors/cell	Total targets per cell	Varied
ε	0.24	-	Intracellular void fraction	(23)
D	1 × 10−11	m2/s	Diffusivity	(14)
P	3 × 10−9	m /s	Vascular permeability	(24)
Pmax	0.014	-	Maximum probability for cell killing	Calibrated
Km	800	nM	Michaelis-Menten constant	Calibrated
td (in vivo)	5–17	days	In vivo doubling time	Calibrated
td (in vitro)	1–2.5	days	In vitro doubling time	Estimated

^*1 million receptors per cell corresponds to 833nM receptors where each cell occupies about 2× 10⁻¹² L.