Clinical Characteristics and Spatial Transcriptome Analysis of Non–Small Cell Lung Cancers Exhibiting Early Alectinib Resistance: A Retrospective OLCSG Study

Some anaplastic lymphoma kinase (ALK) gene rearrangement–positive lung cancers show early resistance, within 3 months, to alectinib. This study investigated the clinical and molecular characteristics of these patients. We analyzed patients with unresectable stage III/IV disease without indications for radical radiotherapy and recurrent ALK-positive lung cancer who received alectinib as the primary ALK tyrosine kinase inhibitor between 2013 and 2021 at nine hospitals. In total, 103 patients were included. The median age was 65 years; 44 were male and 22 had brain metastases. The median progression-free survival and overall survival (OS) were 28.7 and 80.6 months. Nineteen patients treated for ≤3 months and 84 treated for >3 months were categorized into the early resistance and responder groups, respectively. The early resistance group had significantly shorter OS (8.4 months vs. not estimable, P < 0.001) and was significantly more likely to have brain metastases (42% vs. 17%, P = 0.027). They also showed elevated inflammatory markers, including neutrophil-to-lymphocyte ratio (NLR). Univariate analysis identified brain metastases and high NLR as significant predictors of early resistance. Spatial transcriptome analysis and immunohistochemical staining revealed upregulation of annexin A1 (ANXA1), a calcium-dependent phospholipid-binding protein involved in inflammation and cancer progression, in the early resistance group. Interleukin 6 stimulation, prompted by elevated inflammatory markers, increased ANXA1 expression and reduced alectinib sensitivity. Knockdown of ANXA1 improved alectinib sensitivity in alectinib-resistant cells. In conclusion, brain metastases and high NLR are associated with early resistance. ANXA1 may play an important role in mediating early resistance. New treatment options for the early resistance group are required.