In a proof of concept study, mice bearing PD-L1 -ve and +ve xenograft tumours were administered 18F-BMS-986192 (labelled anti- PD-L1 adnectin) systemically which specifically bound to PD-L1 +ve regions.127 Another anti- PD-L1 adnectin radiotracer also proved to correlate clinically with PD-L1 tumour expression and tumour lesion response to therapy.120 While statistically significant correlation for overall patient response to therapy as a whole was not demonstrated, the small sample size (n = 13) rather than poor radiotracer capability could account for this shortcoming. The gene discussed is CD274; the disease is neoplasm.