Project description:With the advent of potent second-line anti-androgen therapy, we and others have observed an increased incidence of androgen receptor (AR)-null small cell or neuroendocrine prostate cancer (SCNPC) in metastatic castration-resistant prostate cancer (mCRPC). Additionally, we have detected upregulated expression of MET and RET transcripts in SCNPC metastases relative to adenocarcinoma. Our study was designed to determine the effect of cabozantinib, a multi-targeted tyrosine kinase inhibitor that inhibits MET, RET and VEGFR2, on SCNPC patient-derived xenografts (PDX) in vivo. Surveillance of SU2C and University of Washington rapid autopsy mCRPC cohorts through RNA-Seq revealed that increased MET expression significantly correlated with loss of AR expression and activity. In vitro treatment of SCNPC PDX cells with AMG 337 had no impact on cell viability in LuCaP 93 (MET+/RET+) and LuCaP 173.1 (MET-/RET-), whereas cabozantinib decreased cell viability in LuCaP 93, but not in LuCaP 173.1. Notably, tumor volume was significantly decreased (p<0.001) with cabozantinib treatment in SCID mice bearing LuCaP 93 and LuCaP 173.1 tumors. Tissue analysis indicated that tumor cell proliferation was not inhibited by cabozantinib, but that cabozantinib decreased microvessel density (CD31) in LuCaP 93 (p<0.001) and LuCaP 173.1 (p<0.01) tumors. RNA-Seq and gene set enrichment analysis determined that hypoxia and glycolysis pathways were increased in cabozantinib treated tumors relative to control tumors. Thus, cabozantinib inhibited tumor growth in MET+/RET+ LuCaP 93 and MET-/RET- LuCaP 173.1 tumors in vivo and this activity was independent of MET or RET expression in LuCaP 173.1. Our data suggest that the most likely mechanism of tumor growth suppression is through disruption of the stromal architecture and cabozantinib may represent a potential therapy for patients with metastatic disease in tumor phenotypes that have a significant dependence on the tumor vasculature for survival and proliferation.

Project description:Background & Aims: Immune checkpoint inhibitors combined with anti-angiogenic agents produces benefits in the treatment of advanced hepatocellular carcinoma (HCC). We investigated the efficacy and immunomodulatory activity of cabozantinib alone and combined with anti-PD1 in experimental models of HCC, and explored the potential target population that might benefit from this combination. Approach & Results: C57BL/6J mice bearing subcutaneous Hepa1-6 or Hep53.4 tumours received cabozantinib, anti-PD1, their combination or placebo. Tumour and blood samples were analysed by flow cytometry, immunohistochemistry, transcriptome and cytokine profiling. Cabozantinib-related effects were validated in a colorectal cancer PDX model. Transcriptomic data from three human HCC cohorts (Cohort 1: n=167, Cohort 2: n=57, TCGA: n=319) were used to cluster patients according to neutrophil features, and assess their impact on survival. The combination of cabozantinib and anti-PD1 showed increased anti-tumour efficacy compared to monotherapy and placebo (P<0.05). Cabozantinib alone significantly increased neutrophil infiltration and reduced CD8+PD1+ T cell proportions in the tumour, while the combination with anti-PD1 further stimulated both effects and significantly decreased T regulatory cell infiltration (all P<0.05). In blood, cabozantinib and especially combination increased the proportions of overall T cells (P<0.01) and memory/effector T cells (P<0.05), while lowering the neutrophil-to-lymphocyte ratio (P<0.001 for combination). Unsupervised clustering of human HCCs revealed that high tumour enrichment in neutrophil features observed with the treatment combination was linked to less proliferative phenotypes, and well-differentiated HCC with better prognosis. Neutrophil recruitment in both humans and mice was linked to CXCR2 ligands and CXCL12 (P<0.05). Conclusions: Cabozantinib in combination with anti-PD1 enhanced anti-tumour immunity by bringing together innate neutrophil-driven and adaptive immune responses, a mechanism of action which favours this approach for the treatment of HCC.

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Cabozantinib Plus Durvalumab With or Without Tremelimumab in Patients With Gastroesophageal Cancer and Other Gastrointestinal Malignancies

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