Median OS was 4.3 years in NET G3, 1.8 years in NEC <55% and 0.7 years in NEC ≥55% (p<0.0001); it was 2.3 years with NGS Wild-Type, 0.7 years with ≥1 mutation (p<0.0001), 0.8 years in PD-L1 positive patients and 1.7 years in PD-L1 negative subjects (p=0.0004).
By combining CD3+ cells and PD-L1 status, we identified the immune ignorant phenotype of tumor microenvironment as being the most common phenotype, supporting the concept of a preferably combined immunotherapeutic approach in neuroendocrine carcinoma (NEC).
These findings suggest that the PD-1/PD-L1 pathway is activated in the microenvironment of pulmonary high-grade neuroendocrine carcinoma and correlated with a higher mutation burden.
Tumor sections were immunohistochemically labeled for PD-1 and PD-L1, and expression of PD-1 and PD-L1 on tumor and tumor-associated immune cells was analyzed and compared between small cell and large cell neuroendocrine carcinomas.