Table 1.

Comparison of the different studies testing soluble programmed death-ligand 1 (sPD-L1).

Study	Patients (n)	Time of sPD-L1 Measure	sPD-L1 Cut-Off	Treatment	Main Results
Zhang et al. [19]	Advanced NSCLC (109), healthy controls (65)	Diagnosis	0.636 ng/mL	NS	Higher sPD-L1 levels in patients than controls Shorter OS in high sPD-L1 patients
Okuma et al. [20]	Advanced or postsurgical recurrent lung cancer (96)	Before initiation of CT or at least 3–4 weeks after last CT	7.32 ng/mL	CT	Shorter OS in high sPD-L1 patients
Zhao et al. [23]	Locally advanced or inoperable NSCLC (126)	Diagnosis, Week 2 and 4 of treatment	0.0965 ng/mL	TRT ± CT	Decrease of sPD-L1 during TRT Shorter OS in high sPD-L1 patients
Okuma et al. [24]	Advanced or recurrent NSCLC (39)	Baseline	3.357 ng/mL	nivolumab	Shorter OS TTF in high sPD-L1 patients Higher rates of CR, PR, and SD in low sPD-L1 patients
Costantini et al. [25]	Advanced NSCLC (43)	At initial diagnosis, at nivolumab initiation, at first tumor evaluation	0.0337 ng/mL	nivolumab	sPD-L1 at first tumor evaluation higher in non-responders Patients with clinical benefit had lower sPD-L1 levels at first tumor evaluation Patients with increasing sPD-L1 levels had worse ORR, lower rates of clinical benefit, shorter PFS and OS

NSCLC: Non-small cell lung cancer. CT: Chemotherapy. TRT: Thoracic radiotherapy. NS: Not specified.