Conclusion
These studies demonstrate that 111In-DTPA-anti-PD-L1 is capable of identifying tumors that overexpresses PD-L1 and monitoring the impact of PD-L1-rich organs on the distribution of anti-PD-L1 antibodies.
Methods
We evaluated the impact of protein concentration on the distribution of 111In-DTPA-anti-PD-L1 in a murine model of aggressive melanoma.
Results
111In-DTPA-anti-PD-L1 (dissociation constant, 0.6 ± 0.1 nM) demonstrated increased uptake in B16F10 tumors at protein concentrations equaling or exceeding 1 mg/kg at 24 h and 3 mg/kg at 72 h. At 24 h, the PD-L1-rich spleen and lungs demonstrated decreasing uptake with increasing protein concentration. At 72 h, uptake in the thymus was significantly increased at protein concentrations of 3 mg/kg or greater. Both time points demonstrated increased tracer amounts remaining in circulation as the amount of cold antibody was increased.