A successful pembrolizumab treatment case of lung adenocarcinoma after becoming resistant to ALK-TKI treatment due to G1202R mutation.BACKGROUND
 Pembrolizumab was selected for the fourth line, leading to PR for more than 6 months.



pembrolizumab
A 51-year-old woman with lung adenocarcinoma harboring ALK translocation was treated with alectinib until PD.  While alectinib might induce resistance to ALK-TKI, it could increase PD-L1 positive cells to become sensitive to PD-1/PD-L1 inhibitors.
alectinib
After the second (CDDP/PEM) and third (crizotinib) line treatment, a second biopsy was performed, revealing PD-L1 tumor proportion score of 70-80% and G1202R mutation of ALK. 
crizotinib
After the second (CDDP/PEM) and third (crizotinib) line treatment, a second biopsy was performed, revealing PD-L1 tumor proportion score of 70-80% and G1202R mutation of ALK. 
CDDP/PEM