Efficacy and safety of alectinib in ALK-positive non-small cell lung cancer and blood markers for prognosis and efficacy: a retrospective cohort study

Background: Alectinib is a second generation of ALK-tyrosine kinase inhibitors (ALK-TKIs), which has attracted much attention in the treatment of ALK-positive non-small cell lung cancer (NSCLC). At present, there are few reports on the efficacy and safety of alectinib in Chinese population. Moreover, biomarkers reflecting prognosis and efficacy are exceedingly needed. This study assessed the efficacy of alectinib in patients with ALK-positive NSCLC and analyzed the prognostic factors.Methods: Patients with ALK-positive NSCLC who were confirmed by histopathology or cytology at the Affiliated Cancer Hospital of Nanjing Medical University between October 2018 and October 2021 were enrolled. All patients were treated with alectinib. The clinical characteristics and circulating tumor biomarkers before and after treatment were collected. Kaplan-Meier test was used to calculate the progression-free survival (PFS). Univariate and multivariate Cox regression analyses were used to explore the influencing factors on PFS. Incidence of adverse events was observed.Results: Twenty patients progressed after first-line treatment (n=59) with alectinib, and 21 patients progressed following second-line treatment (n=36) with alectinib. The median PFS of first-line treatment patients was not achieved, and the median PFS of patients undergoing second-line treatment was 15.0 months [95% confidence interval (CI): 0.00-32.23]. The most common adverse reactions were liver dysfunction (37.50%), anemia (37.50%), and constipation (20.83%). The incidence of grade III and above adverse reactions was 6.25%. Univariate analysis showed that neutrophil-to-lymphocyte ratio [NLR; hazard ratio (HR) =0.424, P=0.005] carcinoembryonic antigen (CEA; HR =0.482, P=0.0 29), lactate dehydrogenase (LDH; HR =0.327, P=0.000), carbohydrate antigen (CA)199 (HR =0.313, P=0.002), and circulating cell free DNA (cfDNA; HR =0.229, P=0.008) concentration levels were associated with PFS, and multivariate analysis showed that NLR (HR =3.058, P=0.034) was independent prognostic factor. After three months of treatment, CEA, CA199, NLR, and LDH, could further predict the prognosis of alectinib treatment. Conclusions: The efficacy and safety of alectinib as a first-line or second-line treatment for ALK-positive NSCLC in keeping with published prospective studies. CEA, CA199, NLR, and LDH within the normal range after three months of treatment were associated with good prognosis. Detection of serum tumor markers can indicate therapeutic success in patients treated with alectinib.