Activity of ERβ on CD274/PD-L1 promoter.
Chromatin immunoprecipitation of ERE1 and ERE2 regions from CD274/PD-L1 promoter, using an anti-ERα or an anti-ERβ antibody, followed by RT-PCR (technical triplicates) of the precipitated products, in ERα highNCI-H1975 cells, grown 24 h in fresh medium (Ctrl) or in medium containing 10 nM fluvestrant (Fulv), an ERα inhibitor, or 10 nM letrozole (Letr), an aromatase inhibitor. Data are means+SD (n=3). **p<0.01, ***p<0.001: treated cells versus Ctrl cells; °°°p<0.001: anti-ERβ versus anti-ERα.
ARTICLE ABSTRACT
Purpose: The response to immune checkpoint inhibitors (ICI) often differs between genders in non-small cell lung cancer (NSCLC), but metanalyses results are controversial, and no clear mechanisms are defined. We aim at clarifying the molecular circuitries explaining the differential gender-related response to anti-PD1/anti-PD-L1 agents in NSCLC. Experimental Design: We prospectively analyzed a cohort of patients with NSCLC treated with ICI as a first-line approach and we identified the molecular mechanisms determining the differential efficacy of ICI in 29 NSCLC cell lines of both genders, recapitulating patients’ phenotype. We validated new immunotherapy strategies in mice bearing NSCLC patient-derived xenografts and human reconstituted immune system (“immune-PDXs”). Results: In patients, we found that estrogen receptor α (ERα) was a predictive factor of response to pembrolizumab, stronger than gender and PD-L1 levels, and was directly correlated with PD-L1 expression, particularly in female patients. ERα transcriptionally upregulated CD274/PD-L1 gene, more in females than in males. This axis was activated by 17-β-estradiol, autocrinely produced by intratumor aromatase, and by the EGFR-downstream effectors Akt and ERK1/2 that activated ERα. The efficacy of pembrolizumab in immune-PDXs was significantly improved by the aromatase inhibitor letrozole, which reduced PD-L1 and increased the percentage of anti-tumor CD8+T-lymphocytes, NK cells and Vγ9Vδ2 T-lymphocytes, producing durable control and even tumor regression after continuous administration, with maximal benefit in 17-β-estradiol/ERα high female immune-xenografts. Conclusions: Our work unveils that 17-β-estradiol/ERα status predicts the response to pembrolizumab in NSCLC patients. Secondly, we propose aromatase inhibitors as new gender-tailored immune-adjuvants in NSCLC.
