Ana Margarita Contreras S (1), MarÃa GarcÃa-Cremades (1), MarÃa Merino (1), Laurent Blom (1,3), Pedro Berraondo (2), Iñaki F. Trocóniz (1), MarÃa Jesús Garrido (1).
(1) School of Pharmacy. Department of Pharmacy and Pharmaceutical Technology. University of Navarra. 31008. Pamplona. Spain. (2) Division of Gene Therapy and Hepatology. Center for Medical Applied research (CIMA). University of Navarra. 31008. Pamplona. Spain. (3) Department of Pharmacy and Biomolecular Science (PBS). Liverpool John Moores University. Liverpool, L3 5AF. UK.
Objective. To develop a platform PK/PD model for an anti-PD-L1 monoclonal antibody (mAb). PD-L1 is a ligand over-expressed on tumor cells and is able to down-regulate the immune response to enhance tumor proliferation. This study includes serum and tumor levels of an anti-PD-L1 mAb, as well as measures of tumor size and specifics immune biomarkers to stablish a relationship between the mAb treatment and the effect.
Methods. In-vitro assay. The endogenous expression of PD-L1 and the effect over its expression due to different concentrations and times of exposure to an anti-PD-L1 mAb was characterize for B16-OVA cell line by flow cytometry along 72h. Then, three different mechanism of internalization for the mAb were also explored. In-vivo assay. s.c. syngeneic melanoma model was stablish for B16-OVA. Mice were randomly assigned to one control and three different treated groups according to the day when the treatment stars. 100 µg mAb/mouse Q3D x 4 administrations were given i.v. to the treated groups, and tumor growth profiles were recorded. For another group of mice with tumor volume 20-50 mm3, treatment was given as explained above and at different time points serum and tumor mAb’s concentration was measure by ELISA; meanwhile lymphocyte and different immune biomarkers (CD8+-OVA and PD-1) were quantify by flow cytometry. A B16F10 syngeneic melanoma model was used to validate these data. Data from PK/PD assays was analyzed using NONMEM 7.2 and plots were done with R program.
Results. In-vitro assay. PD-L1 is expressed in 100% of B16-OVA cells. An anti-PD-L1 mAb treatment is able to block this expression with not dependence on the time of exposure. However, expression’s recovery seems to be concentration and time-dependent, which suggest a complex mechanism of internalization different than endocytosis. In-vivo assay. One compartmental model describes time profile of an anti-PD-L1 mAb in an in-vivo tumor free mouse model. Tumor growth profiles, explored for B16F10 and B16-OVA cell line, were described by Hahnfeldt’s model [7]. PK/PD analysis is currently ongoing.
Conclusions. Anti-PD-L1 mAb was able to block the PD-L1’s expression at the surface of melanoma cells for more than 72h. The presence of the OVA antigen seems to be the main responsible for the efficacy of the mAb over B16-OVA cells, which is even greater when tumors are treated at earlier stages. Immune response can be modulated by an anti-PD-L1 mAb to promote anti-tumor effect.
References:
[1] Li B, VanRoey M, Wang C, et al. Clin Cancer Res. 2009. Mar 1;15(5):1623-34.
[2] Dong H, Strome SE, Salomao DR, et al. Nat Med. 2002. Aug;8(8):793-800.
[3] Pavan B, Dalpiaz A, Ciliberti N, et al. Molecules. 2008. 13, 1035-1065.
[4] Iwai Y, Ishida M, Tanaka Y, et al. Proc Natl Acad Sci U S A. 2002. Sep 17;99(19):12293-7.
[5] Yu P, Steel JC, Zhang M, et al. Clin Cancer Res. 2010. Dec 15;16(24):6019-28.
[6] Wu C, Zhu Y, Jiang J, et al. Acta Histochem. 2006. 108(1):19-24.
[7] Hahnfeldt P, Panigrahy D, Folkman J, et al. Cancer Res. 1999. Oct 1;59(19):4770-5.
Reference: PAGE 24 () Abstr 3432 [www.page-meeting.org/?abstract=3432]
Poster: Drug/Disease modeling - Oncology