Wednesday, October 07, 2020 The purpose of this retrospective biomarker study of the Canadian Cancer Trials Group (CCTG) MA.31 randomized phase 3 trial (lapatinib vs trastuzumab) of HER2‐positive metastatic breast cancer (MBC) was to evaluate the prognostic and predictive biomarker utility of pretreatment serum programmed death ligand 1 (PD‐L1) levels. Moku P, Shepherd L, Ali SM, Leitzel K, Parulekar WR, Zhu L, Virk S, Nomikos D, Aparicio S, Gelmon K, Drabick J, Cream L, Halstead ES, Umstead TM, Mckeone D, Polimera H, Maddukuri A, Ali A, Nagabhairu V, Poulose J, Pancholy N, Spiegel H, Chen BE, Lipton A. Higher serum PD-L1 level predicts increased overall survival with lapatinib versus trastuzumab in the CCTG MA.31 phase 3 trial (ONLINE). Cancer n/a: 2020. https://acsjournals.onlinelibrary.wiley.com/doi/10.1002/cncr.33149 Conclusions In the CCTG MA.31 trial, serum PD‐L1 was a significant predictive factor: a higher pretreatment serum PD‐L1 level was associated with shorter OS with trastuzumab treatment but with longer OS with lapatinib treatment. Immune evasion may decrease the effectiveness of trastuzumab therapy. Further evaluation of elevated serum PD‐L1 in advanced breast cancer is warranted to identify patients with HER2‐positive MBC who may benefit from novel immune‐targeted therapies in addition to trastuzumab. Cancer Network Story
