Background: The clinical impact of hypomagnesemia induced by necitumumab plus gemcitabine and cisplatin (GCN) as a second-line or later therapy is unclear.
Objective: We aimed to evaluate the clinical characteristics and survival impact of hypomagnesemia induced by this therapy.
Design: This was a sub-analysis of the retrospective multicenter NINJA study.
Methods: Among the 93 patients enrolled in the NINJA study, this subanalysis included 75 patients with baseline serum magnesium concentrations.
Results: The incidence of grade ⩾2 hypomagnesemia was 18.0% in the patients with normal baseline serum magnesium concentrations and 42.8% in those with low concentrations (p = 0.073). The discontinuation rates of GCN treatment owing to hypomagnesemia in each group were 0% and 7.1%, respectively (p = 0.187). The number of necitumumab doses and severity of hypomagnesemia were positively correlated (r = 0.389, p < 0.001). Patients who developed hypomagnesemia in fewer than 21 days after the first dose of GCN (n = 12) had significantly poorer progression-free survival (PFS) than those without the condition (n = 63; median: 4.1 vs 4.4 months, p = 0.048). A similar trend was observed for OS (median: 9.7 vs 15.7 months, p = 0.062). These results were maintained after multivariate analyses (PFS: hazard ratio (HR) 2.46, p = 0.014; OS: HR 2.78, p = 0.021).
Conclusion: GCN as a second-line or later therapy may be tolerable regardless of the patient's baseline serum magnesium concentration. On the other hand, early serum magnesium reduction with this therapy is associated with a poor prognosis. However, caution should be needed because our results lacked sufficient information for confounding variables other than those analyzed here that may influence the correlation between hypomagnesemia and survival.
Keywords: adverse event; hypomagnesemia; lung squamous cell carcinoma; necitumumab; prognosis.
© The Author(s), 2025.