Preclinical pharmacokinetics, pharmacodynamics, tissue distribution, and tumor penetration of anti-PD-L1 monoclonal antibody, an immune checkpoint inhibitor

Abstract

MPDL3280A is a human monoclonal antibody that targets programmed cell death-1 ligand 1 (PD-L1), and exerts anti-tumor activity mainly by blocking PD-L1 interaction with programmed cell death-1 (PD-1) and B7.1. It is being investigated as a potential therapy for locally advanced or metastatic malignancies. The purpose of the study reported here was to characterize the pharmacokinetics, pharmacodynamics, tissue distribution and tumor penetration of MPDL3280A and/or a chimeric anti-PD-L1 antibody PRO304397 to help further clinical development. The pharmacokinetics of MPDL3280A in monkeys at 0.5, 5 and 20 mg · kg(-1) and the pharmacokinetics / pharmacodynamics of PRO304397 in mice at 1, 3 10 mg · kg(-1) were determined after a single intravenous dose. Tissue distribution and tumor penetration for radiolabeled PRO304397 in tumor-bearing mouse models were determined. The pharmacokinetics of MPDL3280A and PRO304397 were nonlinear in monkeys and mice, respectively. Complete saturation of PD-L1 in blood in mice was achieved at serum concentrations of PRO304397 above ∼ 0.5 µg · mL(-1). Tissue distribution and tumor penetration studies of PRO304397 in tumor-bearing mice indicated that the minimum tumor interstitial to plasma radioactivity ratio was ∼ 0.3; saturation of target-mediated uptake in non-tumor tissues and desirable exposure in tumors were achieved at higher serum concentrations, and the distribution into tumors was dose-and time-dependent. The biodistribution data indicated that the efficacious dose is mostly likely higher than that estimated based on simple pharmacokinetics/pharmacodynamics in blood. These data also allowed for estimation of the target clinical dose for further development of MPDL3280A.

Keywords: Anti-PD-L1; PD-L1; pharmacodynamics; pharmacokinetics; tissue distribution; tumor penetration.

Figure 1.

Mean (± SD) serum concentration−time profiles following a single IV administration of 1, 10, and 30 mg·kg⁻¹ PRO304397 to BALB/c mice. N = 3 mice per time point per group. The minimum quantifiable concentration (MQC) in the PRO304397 concentration ELISA was 0.0078 µg·mL⁻¹. Values below MQC were interpreted as missing for summary statistics.

Figure 2.

Saturation of PDL1 on CD8⁺ (A) and CD4⁺ (B) T lymphocytes following single IV administration of 1, 10, and 30 mg·kg⁻¹ PRO304397 to BALB/c mice. N = 3 mice per group/per time point, where 3 mice were sacrificed at each time point per group. Saturation of PDL1 was assessed via flow cytometry by measuring the amount of free membrane PDL1 present on the cell surface of peripheral blood CD8 ⁺ and CD4 ⁺ T lymphocytes. Biotin-conjugated PRO304397 was used to stain peripheral blood mononuclear cells and detected with streptavidin-phycoerythrin (SA-PE). Values were normalized against an appropriate isotype control. Mean (+/−SD) fluorescence values for each group are represented as molecules of equivalent fluorescence (MOEF).

Figure 3.

Mean (± SD) serum concentration-time profiles following a single IV administration of 0.5, 5, and 20 mg·kg⁻¹ MPDL3280A to cynomolgus monkeys. N = 4 animals per group. The minimum quantifiable concentration (MQC) in the MPDL3280A concentration ELISA was 0.075 μg·mL⁻¹. Values below MQC were interpreted as missing for summary statistics.

Figure 4.

Plasma and tissue radioactive level following a single IV bolus administration of ¹²⁵I- PRO304397 along with 0–40 mg·kg⁻¹unlabeled antibody to MC38 tumor-bearing mice. (A) Plasma radioactivity levels at 24 and 168 h post-dose. The data are presented as average percent injected dose per milliliter of plasma (%ID·mL⁻¹). (B) The tissue radioactivity levels at 24 h post-dose. The data are presented as average percent injected dose per gram of tissue (%ID·g⁻¹). (C) Tumor interstitial to plasma ratio at 24 and 168 h post-dose. For all figures, the error bars are the standard deviation of 3 measurements.

Figure 5.

Plasma and tissue radioactive level following a single IV bolus administration of ¹²⁵I- PRO304397 along with 0–40 mg·kg⁻¹unlabeled antibody to Cloudman tumor-bearing mice. (A) Plasma radioactivity levels at 24, 120, and 168 h post-dose. The data are presented as individual animal percent injected dose per milliliter of plasma (%ID·mL⁻¹) with a line passing through the average. (B) The tissue radioactivity levels at 24 h post-dose. The data are presented as average percent injected dose per gram of tissue (%ID·g⁻¹). (C) Tumor interstitial to plasma ratio at 24, 120, and 168 h post-dose. For all figures, the error bars are the standard deviation of 3 measurements.

Figure 6.

Representative autoradiography images of sagittal tumor sections in tumor-bearing mice following intravenous administration of ¹²⁵I- PRO304397 tracer or ¹²⁵I- PRO304397 tracer + unlabeled PRO304397. (A) Autoradiography sections of MC38 tumors at 24, 48, and 120 h after administration of ¹²⁵I-PRO304397 tracer alone or ¹²⁵I- PRO304397 tracer + 10 mg·kg⁻¹ unlabeled PRO304397, respectively. A heat map (below the tumor images) shows the range of radioactivity from red being the highest to purple the lowest. (B) Representative sagittal sections of MC38 tumors showing cell distribution of ¹²⁵I- PRO304397-associated signal by MAR (left) and H&E (right), respectively at 24 and 48 h following ¹²⁵I- PRO304397 tracer alone or ¹²⁵I- PRO304397 tracer + 10 mg·kg⁻¹unlabeled PRO304397. (C) Autoradiography sections of Cloudman tumors at 24, 48, and 72 h after administration of ¹²⁵I- PRO304397 tracer alone or ¹²⁵I-PRO304397 tracer+ unlabeled PRO304397 at 5 and 10 mg·kg⁻¹, respectively. Heat map depicts pseudocolor intensities as described above.

Figure 6.

Figure 6.

(Continued).