ERBB2 and breast cancer: Pivotal trials examining metastatic TN and HER-2-positive breast cancer, including the phase-III KEYNOTE-119 [108], IMpassion130 [109], KEYNOTE-355 [110], phase-II KEYNOTE-086 [111], and phase-Ib/II PANACEA [112] trials, have revealed that the good OS, PFS, and response rates achieved with ICI use may be associated with PD-L1 positivity and TIL abundance in tumors [113], and that TILs are surrogate markers for existing antitumor immunity.