Immunotherapy has changed the paradigm of cancer treatments. In this way, several
combinatorial strategies based on monoclonal antibodies (mAb) such as anti (a)-PD-1 or anti (a)-PD-L1
are often reported to yield promising clinical benefits. However, the pharmacokinetic (PK) behavior
of these mAbs is a critical issue that requires selective analytical techniques. Indeed, few publications
report data on a-PD1/a-PD-L1 exposure and its relationship with therapeutic or toxic effects. In this
regard, preclinical assays allow the time profiles of antibody plasma concentrations to be characterized
rapidly and easily, which may help to increase PK knowledge. In this study, we have developed
and validated two in-house ELISAs to quantify a-PD-1 and a-PD-L1 in plasma collected from
tumor-bearing mice. The linear range for the a-PD-1 assay was 2.5–125 ng/mL and 0.11–3.125 ng/mL
for the a-PD-L1 assay, whereas the intra-and inter-day precision was lower than 20% for both analytes.
The PK characterization revealed a significant decrease in drug exposure after administration of
multiple doses. Plasma half-life for a-PD-1 was slightly shorter (22.3 h) than for a-PD-L1 (46.7 h).
To our knowledge, this is the first reported preclinical ELISA for these immune checkpoint inhibitors,
which is sufficiently robust to be used in different preclinical models. These methods can help to
understand the PK behavior of these antibodies under different scenarios and the relationship with
response, thus guiding the choice of optimal doses in clinical settings