Abstract 164P
Background
Atezolizumab plus carboplatin-etoposide (ACE) represents the new first-line (1L) standard of care for extended stage (ES) Small Cell Lung Cancer (SCLC) patients (pts).
Methods
This is a single-center retrospective-prospective translational study aiming at investigating the correlation of immune cell distribution and their spatial metrics in tumor samples of ES SCLC pts receiving ACE as 1L treatment, with response rate (RR), progression-free survival (PFS), time to treatment failure (TTF) and overall survival (OS). A 9-color multiplex immunofluorescence panel including primary antibodies (Abs) against CD68, CD163, CD8, FoxP3, CD4, CD20 and HLA-I and a mix of Abs against tumor markers has been performed.
Results
Preliminary data on the first 39 pts are reported. After a median follow-up of 7.2 months (mos), the estimated median PFS, TTF and OS were 5.4 (95% CI 4.5–6.3), 5.8 (95% CI 3.5–8.1), and 7.8 mos (95% CI 1.9–13.7), respectively. Lower CD163+ M2-polarized macrophages density and ratio on CD8+ cells in the total and tumoral areas were favorably associated with RR, PFS, TTF and OS (p < 0.05). High intra-tumoral CD4+FoxP3+ density correlated with better PFS (p = 0.004), TTF (p = 0.011) and OS (p = 0.026). CD8+ and CD20+ B lymphocyte infiltration in the total and tumoral areas correlated with longer OS. A positive role of CD20+ interaction with CD8+ on PFS (p = 0.038), TTF (intra-tumoral, p = 0.036) and OS (p = 0.032) has been observed. High percentage (%) of stromal CD163+ close to CD8+ cells and a low % of CD163+ cells close to tumor cells were correlated with longer PFS (p = 0.045) and TTF(p = 0.034). High % of CD4+ closed to CD8+ cells in the total area (p = 0.025) and in the stroma (p = 0.002), intra and peri-tumoral interaction between CD163+ (p = 0.020) and CD8+ cells (p = 0.008), CD8+ and tumor cells interaction (p = 0.012), correlated with longer OS.
Conclusions
We identified that immune cell populations and cell-to-cell spatial metrics in ES-SCLC pts receiving ACE significantly correlated with outcome, highlighting the importance of tumor immune microenvironment and cell-to-cell interaction for tumor response and survival.
Legal entity responsible for the study
University of Padua.
Funding
University of Padua and Istituto Oncologico Veneto.
Disclosure
All authors have declared no conflicts of interest.