Table III.
Parameter | Definition | Unit | Value (CV%) | Source | |
---|---|---|---|---|---|
Binding | konCD3, koffCD3, Kd_CD3 | Binding of PF-06671008 to CD3 |
1/nM/h, 1/h nM |
1.72, 19.66, 11.4 | (7) |
konPcad, koffPcad, Kd_Pcad | Binding of PF-06671008 to P-cadherin | 1.57, 0.74, 0.47 | |||
Central/peripheral compartment | V 1 | Volume of distribution in central compartment | mL/kg | 40.2 |
Allometrically scaled from cynomolgus monkey PK analysis (16) kel = CL/V1 k12 = CLd/V1 k21 = Cld/V2 |
V 2 | Volume of distribution in peripheral compartment | mL/kg | 211 | ||
CL | Clearance | mL/h/kg | 4.61 | ||
CL D | Inter-compartmental clearance | mL/h/kg | 25.2 | ||
sPcad | sPcadherin concentration in central compartment | nM | 1.1 (0.4–4.1) |
Measured in-house (= 92.7 ng/mL) Median value of healthy subjects and patient data |
|
k deg | sPcad degradation rate | 1/h | 0.15 | Allometrically scaled from cynomolgus monkey PK analysis (0.31 1/h in cyno) (16) | |
k degcx | sPcad-PF-06671008 complex degradation rate | 1/h | 0.115 | Assumed to equal PF-06671008 elimination rate (CL/V1) | |
Tcells p | T cell concentration in central compartment | Cells/μL | 5000 | (23) | |
CD3 | CD3 expression on T cells | Receptors/cell | 100,000 | (17,18) | |
Tumor disposition of PF-06671008/T cells | P | Permeability of drug into tumor | μm/d | 334 | (19) |
D | Diffusivity of drug into tumor | cm2/d | 0.022 | ||
ε | Void fraction in tumor for drug | – | 0.24 | ||
Rcap | Capillary radius | μm | 8 | ||
Rkrogh | Average distance between 2 capillaries | μm | 75 | ||
Tcells t a | Number of T cells in tumor | Cells/g of tumor | 6.49e5 | (24) | |
Tumor cellst | Number of Tumor cells | Cells/g of tumor | 1e8 | (21) | |
mPcad | P-cadherin expression on tumor cells | Receptors/cell | 28,706 | (15) | |
Rtumor | Tumor radius | cm | 1 | Assumed | |
k int | Internalization rate with PBMCs | Day−1 | 0.1728 (−) | Estimated from mouse tumor PK data. Represents 96 h half-life of internalization. |
aAssume no proliferation in tumor; ksyn = kdeg*sPcad. MWt of PF-06671008 = 105 kDa, MWt of sPcad = 85 kDa