TABLE 1

Definitive phenotyping and kinetic determination utilizing HLMs and recombinant P450

In vitro, no metabolism of axitinib by 100 pmol/ml rCYP2B6 was observed.

Enzyme	Chemical Inhibition CYP Phenotyping			Recombinant CYP Phenotyping			Kinetic Determination of Axitinib Sulfoxide
Enzyme	Chemical Inhibitor	CL_int,u,app	Relative Contribution^{^a}	ISEF Adjusted CL_int,u,app^{^b}	Relative Contribution	Forms Sulfoxide Metabolite	K_m	V_max	CL_int
		µl·min⁻¹·mg⁻¹	%	µl·min⁻¹·mg⁻¹	%		μM	pmol·min⁻¹·pmol⁻¹ (rP450) or pmol·min⁻¹·mg⁻¹	µl·min⁻¹·pmol⁻¹ or µl·min⁻¹·mg⁻¹
CYP1A2	30 μM Furafylline	108.1	0	24.4	7.7	No	N/A	N/A
CYP2C8	0.2 μM Montelukast	101.8	2.60	N/A	N/A	Yes	N/A	N/A
CYP2C9	5 μM Sulphaphenazole	98.4	5.30	N/A	N/A	Yes	N/A	N/A
CYP2C19	5 μM Benzylnirvanol	97.2	6.40	1.20	0.38	Yes	5.9 ± 0.9	0.1 ± 0.01	0.017
CYP2D6	1 μM Quinidine	95.8	7.50	0.040	0.13	No	N/A	N/A
CYP3A4	1 μM Ketoconazole	11.4	78.2^{^c}	291	91.8	Yes	4.0 ± 0.4	9.60 ± 0.3	2.4
CYP3A5	N/A		N/A	—	—	Yes	2.1 ± 0.3	1.39 ± 0.1	0.66
HLM	N/A	104.6	N/A	94.5	N/A	Yes	6.2 ± 1.0	1078 ± 61^{^d}	173.9

N/A, not applicable; —, no ISEF available.
↵^a Percent contribution for each isozyme was converted to relative % contribution due to the small overlap of some inhibitors on multiple isozymes. In cases where total % contribution is >100%, there is a requirement to normalize the data to 100% while still retaining the same proportional contribution by each CYP.
↵^b rCYP clearances require scaling from μl/min/pmol to μl/min/mg microsomal protein, using the most appropriate CYP ISEFs.
↵^c Cumulative effect of ketoconazole on CYP3A4 and CYP3A5.
↵^d The V_max value for HLM is expressed as pmol/min/mg.