Progression patterns, resistant mechanisms and subsequent therapy for ALK-positive NSCLC in the era of second-generation ALK-TKIs

Background In the era of second-generation ALK tyrosine kinase inhibitors (ALK-TKIs), there was a paucity of data regarding the progression patterns, resistant mechanisms, and subsequent therapeutic approaches for ALK-positive (ALK+) non-small cell lung cancer (NSCLC).Methods Patients with advanced ALK+ NSCLC were retrospectively selected from our center. Cohort 1 consisted of patients who experienced disease progression after receiving first-line alectinib treatment (n = 20), while Cohort 2 included patients who progressed following sequential treatment with crizotinib and second-generation ALK-TKIs (n = 53). Oligo-progression was defined as the occurrence of disease progression in no more than three lesions. Symptomatic progression was determined when patients developed new symptoms or experienced worsening of pre-existing symptoms during radiological progression.Results The incidence of central nervous system (CNS) progression and symptomatic CNS progression was significantly lower in Cohort 1 compared to patients treated with crizotinib, with rates of 15.0% vs. 56.6% (p = 0.002) and 5.0% vs. 32.1% (p = 0.016), respectively. A total of 60.3% (44/73) patients underwent repeated biopsy and next-generation sequencing subsequent to the second-generation ALK-TKI resistance, with secondary mutation in ALK kinase domain emerging as the predominant mechanism of resistance (56.8%). Local therapy was applied to 50% of oligo-progression cases. Subsequent ALK-TKIs demonstrated significantly prolonged progression-free survival (PFS) (8.6 m vs. 2.7 m, p = 0.021, HR = 0.43, 95%CI: 0.15-0.85) and long-term overall survival (OS) (NA vs. 11.9 m, p = 0.132, HR = 0.50, 95%CI: 0.18-1.25) in patients harboring ALK resistance mutations, compared to those without such mutations. For patients without ALK-resistant mutations following progression on second-generation ALK-TKIs, there was no statistically significant difference in survival outcomes between subsequent chemotherapy or alternative ALK-TKI treatments.Conclusions First-line alectinib demonstrated superior efficacy in protecting the CNS compared to crizotinib. For patients with ALK-resistant mutations following the resistance to second-generation ALK-TKIs, appropriate sensitive ALK-TKI should be administered; for those without such mutations, the selection of chemotherapy or third-generation ALK-TKI should be based on the patient's overall physical health and personal preferences.