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MA17 - Molecular Mechanisms and Therapies (ID 143)
- Event: WCLC 2019
- Type: Mini Oral Session
- Track: Biology
- Presentations: 1
- Now Available
- Moderators:Eloisa Jantus-Lewintre, Hongbin Ji
- Coordinates: 9/09/2019, 15:45 - 17:15, Melbourne (1991)
MA17.11 - High Sensitivity to PD-1 Blockade Therapy After Ld1 Depletion in KRAS-Driven Lung Cancer Through CD8+/CD3+ Tumor Infiltration and PD-L1 Induction (Now Available) (ID 2562)
15:45 - 17:15 | Presenting Author(s): Iosune Baraibar
PD-1/PDL-1 inhibitors are approved for non-small cell lung cancer (NSCLC). However, many patients do not benefit and therapeutic combinations are under investigation. We have previously described Id1, involved in proliferation, angiogenesis and immunosuppression, as a prognostic factor in lung adenocarcinoma (LUAD) (Ponz-Sarvise, Clin Cancer Res 2011), Id1’s role in lung cancer metastasis (Castanon, Cancer Letters 2017) and more recently shown that Id1 sustains mutant KRAS-driven progression and metastasis in NSCLC (Roman, Cancer Res 2019).
In a previous syngeneic murine lung cancer model with depleted levels of Id1 using Id1-/- and Id1 wildtype C57BL/6 mice inoculated with Lewis Lung Carcinoma (LLC), we tested a combined therapeutic strategy targeting PD-1 and Id1, showing impaired tumor growth and increased survival (Gil-Bazo, presented at WCLC 2018).
Here we study a combined strategy targeting PD-1 and Id1 in a KRAS-mutant murine LUAD model and the immune-related mechanisms involved.Method
First, a correlation between Id1 and PD-L1 mRNA expression was studied in mutant and wild-type KRAS LUAD cohorts from The Cancer Genome Atlas data set (TCGA).
Secondly, a syngeneic tumor model using Balb/c mice through subcutaneous injection of KRAS-mutant LUAD (Lacun3) cells and Id1-silenced Lacun3 (Id1sh) cells. In vitro, proliferation was measured in both cell lines through MTS assays. IFNg-induced PD-L1 expression in both cell lines and flow cytometry was used to evaluate its mechanistic effects on the immune response.
After tumor cells injection, mice were treated with an anti-PD-1 (RMP-1-14) monoclonal antibody or PBS, i.p. Tumor volumes according to Id1 status in tumor cells and the treatment administered were quantified. Vectra 3.0™ multispectral microscopy was used to characterize the tumor associated immune cells in paraffin-embedded tissues from our previous syngeneic murine lung cancer model using Id1-/- and Id1 wildtype C57BL/6 mice inoculated with LLC in which the combined blockade had been reported as effective. Immune marker antibodies were used to study expression of CD3, CD4 and CD8.Result
An inverse, moderate and statistically significant correlation between Id1 and PD-L1 expression in mutant and wild-type KRAS LUAD cohorts from TCGA was found in both cohorts (-0.367 and -0.351, respectively, p<0.001), indicating that Id1 depletion may lead to PD-L1 expression induction.
In vitro assays showed that Id1 silencing reduced Lacun3 cells proliferation (p<0.001). Up-regulation of surface PD-L1 expression occurred in Id1sh cells, but not in Lacun3 cells, after receiving IFNg (p=0.0022). Mechanistically, in the syngeneic murine model, Id1 inhibition in the injected cells, combined with anti-PD-1 treatment, significantly induced a tumor growth impairment (p<0.001). An intense CD8+ and CD3+ immune cell infiltration was observed in LLC Id1-/- C57BL/6 mice treated with anti-PD1 (p<0.05 for CD3+ TILS), compared the control groups, possibly explaining the dramatic tumor growth impairment previously shown on the treated animals.Conclusion
Id1 silencing may induce PD-L1 overexpression according to in silico and in vitro results. Id1 and PD-1 combined blockade in our KRAS-mutant syngeneic murine LUAD model significantly impaired tumor growth, compared to each strategy alone. A significantly increased CD3+ and CD8+ tumor infiltration and IFNg-induced PD-L1 tumor expression after the combined blockade may explain these findings.
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