Evaluation of potential biomarkers for lenvatinib plus pembrolizumab among patients with advanced endometrial cancer: results from Study 111/KEYNOTE-146.

BACKGROUND: Lenvatinib plus pembrolizumab demonstrated clinically meaningful benefit in patients with previously treated advanced endometrial carcinoma in Study 111/KEYNOTE-146 (NCT02501096). In these exploratory analyses from this study, we evaluated the associations between clinical outcomes and gene expression signature scores and descriptively summarized response in biomarker subpopulations defined by tumor mutational burden (TMB) and DNA variants for individual genes of interest. METHODS: Patients with histologically confirmed metastatic endometrial carcinoma received oral lenvatinib 20 mg once daily plus intravenous pembrolizumab 200 mg every 3 weeks for 35 cycles. Archived formalin-fixed paraffin-embedded tissue was obtained from all patients. T-cell-inflamed gene expression profile (TcellinfGEP) and 11 other gene signatures were evaluated by RNA sequencing. TMB, hotspot mutations in PIK3CA (oncogene), and deleterious mutations in PTEN and TP53 (tumor suppressor genes) were evaluated by whole-exome sequencing (WES). RESULTS: 93 and 79 patients were included in the RNA-sequencing-evaluable and WES-evaluable populations, respectively. No statistically significant associations were observed between any of the RNA-sequencing signature scores and objective response rate or progression-free survival. Area under the receiver operating characteristic curve values for response ranged from 0.39 to 0.54; all 95% CIs included 0.50. Responses were seen regardless of TMB (≥175 or <175 mutations/exome) and mutation status. There were no correlations between TcellinfGEP and TMB, TcellinfGEP and microvessel density (MVD), or MVD and TMB. CONCLUSIONS: This analysis demonstrated efficacy for lenvatinib plus pembrolizumab regardless of biomarker status. Results from this study do not support clinical utility of the evaluated biomarkers. Further investigation of biomarkers for this regimen is warranted. TRIAL REGISTRATION NUMBER: NCT02501096.

Inhibition of Notch4 Using Novel Neutralizing Antibodies Reduces Tumor Growth in Murine Cancer Models by Targeting the Tumor Endothelium.

Endothelial Notch signaling is critical for tumor angiogenesis. Notch1 blockade can interfere with tumor vessel function but causes tissue hypoxia and gastrointestinal toxicity. Notch4 is primarily expressed in endothelial cells, where it may promote angiogenesis; however, effective therapeutic targeting of Notch4 has not been successful. We developed highly specific Notch4-blocking antibodies, 6-3-A6 and humanized E7011, allowing therapeutic targeting of Notch4 to be assessed in tumor models. Notch4 was expressed in tumor endothelial cells in multiple cancer models, and endothelial expression was associated with response to E7011/6-3-A6. Anti-Notch4 treatment significantly delayed tumor growth in mouse models of breast, skin, and lung cancers. Enhanced tumor inhibition occurred when anti-Notch4 treatment was used in combination with chemotherapeutics. Endothelial transcriptomic analysis of murine breast tumors treated with 6-3-A6 identified significant changes in pathways of vascular function but caused only modest change in canonical Notch signaling. Analysis of early and late treatment timepoints revealed significant differences in vessel area and perfusion in response to anti-Notch4 treatment. We conclude that targeting Notch4 improves tumor growth control through endothelial intrinsic mechanisms. SIGNIFICANCE: A first-in-class anti-Notch4 agent, E7011, demonstrates strong antitumor effects in murine tumor models including breast carcinoma. Endothelial Notch4 blockade reduces perfusion and vessel area.