Real-World Patient Characteristics, Treatment Patterns and Clinical Outcomes in Patients Diagnosed With Extra-Pulmonary Neuroendocrine Carcinoma (epNEC): A Non-Interventional Multimodal Database Analysis in the US

Background
Extra-pulmonary neuroendocrine carcinomas (epNECs) represent a rare and aggressive subset of malignant neuroendocrine neoplasms associated with poor outcomes and an incidence rate of approximately 1 per 100,000 individuals. While evidence-based treatment recommendations are lacking, platinum-based chemotherapy, extrapolated from small cell lung cancer, remains the consensus first-line (1L) treatment with no standard in second-line (2L). Significant gaps persist in our understanding of epNEC, with limited data available on epidemiology, treatment, and outcomes. This study aims to characterize real-world patient characteristics, treatment patterns, and clinical outcomes in patients diagnosed with epNEC in the US.

Methods
In this retrospective study, patients diagnosed with epNEC and treated with 1L therapy were identified from August 2012 to March 2025 using the Tempus multimodal dataset. The Tempus data model includes de-identified pan-cancer longitudinal data linked to claims data from the Komodo Healthcare Map. Baseline patient characteristics and treatment patterns were evaluated. Real-world progression-free survival (rwPFS) and overall survival (rwOS) were estimated using Kaplan-Meier risk-set–adjusted methods by line of therapy.

Results
Of 146 patients diagnosed with epNEC and treated with 1L therapy (median age 61 years; 42% female; 56% white), most tumors originated from the gastrointestinal tract (82%) and 83% had stage III/IV disease at initial diagnosis. 1L treatment (N = 146) was predominantly platinum- etoposide-based (n = 122, 84%), with 62% (n = 90) receiving platinum-etoposide alone, supporting its role as the standard of care regimen in the 1L setting; 20% (n = 29) of patients received immunotherapy as part of their 1L treatment. Of all patients who received 1L treatment, median rwPFS and rwOS were 4.8 and 9.0 months. Among patients treated with 1L platinum-etoposide alone, median rwPFS and rwOS were 3.5 and 7.0 months. Among patients treated with 1L chemotherapy in combination with immunotherapy, median rwPFS and rwOS were 4.8 and 9.9 months. Of 1L-treated patients, 40% (N = 58) were treated with 2L therapy. 2L treatments were heterogeneous reflecting a lack of consensus or effective options after progression on 1L therapy. Median rwPFS and rwOS were 1.8 and 4.7 months in 2L.

Conclusions
This real-world analysis demonstrates poor outcomes in patients diagnosed with epNEC, despite platinum-etoposide-based therapy as the consensus 1L standard of care. In the 2L setting, where standard of care treatment is lacking, survival continues to be poor demonstrating a high unmet need in this patient population. These data underscore the need for innovative treatment strategies to improve survival in this highly aggressive disease.