Here, we describe a male patient with stage IV lung adenocarcinoma who carried a novel PTH2R-ALK fusion identified by next-generation sequencing (NGS). The patient first took crizotinib but switched to alectinib due to gastrointestinal AEs….During treatment with dose reduction of ceritinib, the patient’s blood routine tests and liver function tests were normal, and chest CT scan demonstrated stable disease....The tumor lesion in the left lung remained stable and PFS was nearly 12 months....This patient responded to crizotinib and alectinib well, but had to discontinue due to AEs. After switching to dose reduction of ceritinib, he kept stable disease till now without insufferable AEs (Figure 3).