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PURPOSE Actionable genomic alterations (AGA) are rare in large cell neuroendocrine carcinoma (LCNEC), and outcomes with small molecule inhibitors (SMI) are not well studied. We evaluated SMI response in LCNEC with AGAs, and also assessed molecular testing rates using the nationwide Netherlands Cancer Registry (NCR). MATERIALS AND METHODS In this European multicenter cohort, clinical data were collected from patients with LCNEC harboring AGAs (age 18 years and older) who were treated with an SMI. Overall survival (OS) was calculated from first-line systemic treatment to death or last follow-up. Radiologic response was evaluated for each treatment line. Molecular (AGA and retinoblastoma 1 gene RB1 ) and immunohistochemical (protein RB1 pRb and Ki-67) data were collected. NCR data were analyzed to determine molecular testing frequency and AGA types in stage IV LCNEC (2016-2022). RESULTS In total, 28 patients with LCNEC were identified. The most common AGAs were epidermal growth factor receptor mutations (35.7%) and anaplastic lymphoma kinase fusions (32.1%). Median OS was 14.6 months (95% CI, 11 to 32). Across 38 SMI treatment lines, partial response was observed in 19 (50%). A trend toward longer survival was seen in patients with functional RB1 versus inactivated RB1 (hazard ratio, 0.32 95% CI, 0.12 to 1.03; P = .057). Within the NCR, molecular testing was conducted in 498/927 (53.7%) patients with stage IV LCNEC in the Netherlands, with AGAs detected in 111/498 (22.3%). CONCLUSION In our series, patients with LCNEC harboring AGAs who are treated with SMIs achieved a response in 50% of cases, including durable responses. However, only half of the patients with LCNEC are screened for AGAs. These findings highlight the need for standardized testing for AGAs in LCNEC.
Heijboer et al. (Sat,) studied this question.