Table 5.

Summary of studies that investigated the correlation between OS and surrogate endpoints

Cancer type	Investigated therapies	Correlation ORR/OS	Correlation PFS/OS	References
All	Anti-PD-1/PD-L1	R2 = 0.066 (p = 0.251)	R2 = 0.432 (p = 0.032)	[80]
Melanoma	ICIs	R2 = 0.028 (p = 0.279)	R2 = 0.192 (p = 0.154)	[80]
Nonsmall cell lung cancer	ICIs	R = 0.452 (p = 0.141)	R = 0.473 (p = 0.120)	[81]
Renal cell carcinoma	ICIs and other drugs	89–96% for RD, 81–91% for SD, and 50–70% for PD	–	[82]
Urothelial carcinoma	ICIs and other anticancer drugs	R = 0.37 (p = 0.30)	–	[83]

ORR overall response rate, OS overall survival, PD progressive disease, PFS progression-free survival, RD responders (complete/partial response), SD stable disease, PD-1 programmed death 1, PD-L1 programmed death-ligand 1, ICIs immune checkpoint inhibitors