Efficacy of atezolizumab combined with platinum and etoposide in the treatment of extrapulmonary neuroendocrine carcinoma.

Background: Neuroendocrine carcinoma (NEC) is an aggressive, poorly differentiated Grade 3 (G3) tumor with high nuclear and cellular atypia and Ki-67 indices over 20%. While most cases are lung NECs, extrapulmonary NECs are rarer and less studied. Standard treatment involves etoposide and platinum (EP) chemotherapy. Inspired by the IMpower133 study, which showed survival benefits with atezolizumab plus chemotherapy in extensive-stage small-cell lung cancer, this study investigates whether atezolizumab combined with platinum and etoposide can offer similar benefits for extrapulmonary NEC.

Method: This retrospective cohort study, conducted at Taipei Veterans General Hospital from January 2016 to June 2023, compared the efficacy of atezolizumab combined with platinum and etoposide versus standard chemotherapy alone in extrapulmonary NEC patients. The outcomes assessed were response rate, progression-free survival (PFS), and overall survival (OS).

Result: The study evaluated 56 patients: 14 received atezolizumab with platinum and etoposide (EP), while 42 were treated with EP alone. The median PFS was 5.2 months, and median OS was 11.9 months for the whole cohort. While there were no significant differences in OS or PFS between the groups, the response rate was significantly higher in the atezolizumab group. Additionally, a neutrophil-lymphocyte ratio (NLR) above 3 was linked to poorer OS.

Conclusion: The addition of atezolizumab to EP did not improve PFS and OS in extrapulmonary NEC patients but did result in a higher response rate. Moreover, an NLR above 3 at diagnosis was identified as a poor prognostic factor for OS.