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OA05 - Treatment Advances in SCLC (ID 373)
- Event: WCLC 2016
- Type: Oral Session
- Track: SCLC/Neuroendocrine Tumors
- Presentations: 1
OA05.02 - Anti-Tumor Immunity is a Key Determinant of SCLC Survivorship (ID 5759)
14:20 - 15:50 | Author(s): A. Nasir
While the majority of small cell lung cancer (SCLC) patients succumb to their disease within a few months, there is a small group of patients who survive for many years after their diagnosis. Factors contributing to the SCLC long-term survivorship remain largely unknown. Herein, we compared tumors from exceptional survivors (EXS) and patients with the expected outcome (EOP) to determine genomic and immunological determinant of SCLC survivorship.
In the Mayo Clinic tissue registry, we identified surgical blocks from 12 EXS who survived > 4 years after surgery and 14 EOP who died < 2 years of surgery. These cohorts were created to have no statistical differences in clinical TNM stage, curative versus non-curative intent surgery, age, gender, and smoking status between EXS and EOP. Tumor areas were macro-dissected for gene expression profiling by the Human Transcriptome Array (Affymetrix). Also, tissue sections were stained for key immunological markers, including CD8, CD4, CD3, CD279, FoxP3, CD138, CD20, CD21, CD14, CD68, and also LYZ. Concentrations of immune cells in intra-tumor areas (IE), stroma (ST), and tumor/non-tumor interface (IF) were assessed by an image processing program (Aperio). Staining patterns in each of the three zones in EXS and EOP tumors were compared.
More than 90% of differentially expressed genes were over-expressed in EXS compared with EOP. Furthermore, over 75% of the known over-expressed genes were either immunoglobulin or MHC related and a majority of the remaining genes were immune function related such as cytokines. We then performed IHC for key immunological markers and found significantly higher concentration of immune cells including CD8 and PD-1 positive cells in the tumor microenvironment, especially at the tumor stromal interface in EXS compared with EOP (p < 0.005 for both markers). Furthermore, the total number of infiltrating immune cells (T-cells, B-cells, Plasma cells, monocytes and macrophages was significantly higher in EXS in the interface region (p < 0.0005).
Gene expression profiling revealed that anti-tumor immunity is an important factor for SCLC survival. Further studies by IHC suggested the presence of immune cells especially cytotoxic T-cells in the tumor microenvironment and particularly at the tumor-stromal interface to be major contributors to long term survivorship in SCLC. These findings suggest that immunotherapeutic strategies may be effective for patients with SCLC.
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