Long-term survival of an ALK fusion lung adenocarcinoma patient with high mutation burden and microsatellite instability high: a case report.

Immune checkpoint blockage (ICB) therapy has shown minimal effectiveness in anaplastic lymphoma kinase (ALK)-positive nonsmall cell lung cancer (NSCLC) regardless of Programmed death-ligand 1 expression. ALK fusion accompanied by mismatch repair deficiency or microsatellite instability-high (MMRd/MSI-H) and high tumor mutation burden (TMB-H) are extremely rare in NSCLC, and the efficacy of ALK inhibitors or ICB-based therapies is unclear. Here, we report the case of a 60-year-old female patient with metastatic lung adenocarcinoma accompanied by EML4-ALK fusion, TMB-H, MMRd/MSI-H, and pathogenic mutations in TP53, MLH1, and STK11. The patient experienced progression on initial iruplinalkib and subsequent alectinib therapy within 5 months. After the failure of third-line therapy with cisplatin-pemetrexed combined with bevacizumab, she received sintilimab plus anlotinib which led to a progression-free survival of 6.5 months. She received sintilimab combined with albumin-paclitaxel plus carboplatin and achieved partial response after 6 months. She developed adverse events after one cycle of sintilimab plus albumin-paclitaxel treatment. Then she was continued with sintilimab plus anlotinib as a maintenance therapy due to intolerance to chemotherapy. After progression on ICB-based therapy, the patient was treated with lorlatinib and still under follow-up with overall survival of more than 3 years. Our findings highlight the therapeutic potential of ICB-based regimens in patients with MSI-H and ALK-rearranged NSCLC.