Progression of prostate cancer following castration is associated with increased androgen receptor (AR) expression and signaling despite AR blockade. Recent studies suggest that these activities are due to the generation of constitutively active AR splice variants, but the mechanisms by which these splice variants could mediate such effects are not fully understood. Here we have identified what we believe to be a novel human AR splice variant in which exons 5, 6, and 7 are deleted (AR v567es ) and demonstrated that this variant can contribute to cancer progression in human prostate cancer xenograft models in mice following castration. We determined that, in human prostate cancer cell lines, AR v567es functioned as a constitutively active receptor, increased expression of full-length AR (AR fl ), and enhanced the transcriptional activity of AR. In human xenografts, human prostate cancer cells transfected with AR v567es cDNA formed tumors that were resistant to castration. Furthermore, the ratio of AR v567es to AR fl expression within the xenografts positively correlated with resistance to castration. Importantly, we also detected AR v567es frequently in human prostate cancer metastases. In summary, these data indicate that constitutively active AR splice variants can contribute to the development of castration-resistant prostate cancers and may serve as biomarkers for patients who are likely to suffer from early recurrence and are candidates for therapies directly targeting the AR rather than ligand.

Tumor microenvironment (TME) cells constitute a vital element of tumor tissue. Increasing evidence has elucidated their clinicopathologic significance in predicting outcomes and therapeutic efficacy. Nonetheless, no studies have reported a systematic analysis of cellular interactions in the TME. In this study, we comprehensively estimated the TME infiltration patterns of 1,524 gastric cancer patients and systematically correlated the TME phenotypes with genomic characteristics and clinicopathologic features of gastric cancer using two proposed computational algorithms. Three TME phenotypes were defined, and the TMEscore was constructed using principal component analysis algorithms. The high TMEscore subtype was characterized by immune activation and response to virus and IFNg. Activation of transforming growth factor b, epithelial-mesenchymal transition, and angiogenesis pathways were observed in the low TMEscore subtype, which are considered T-cell suppressive and may be responsible for significantly worse prognosis in gastric cancer [hazard ratio (HR), 0.42; 95% confidence interval (CI), 0.33-0.54; P < 0.001]. Multivariate analysis revealed that the TMEscore was an independent prognostic biomarker, and its value in predicting immunotherapeutic outcomes was also confirmed (IMvigor210 cohort: HR, 0.63; 95% CI, 0.46-0.89; P ¼ 0.008; GSE78220 cohort: HR, 0.25; 95% CI, 0.07-0.89; P ¼ 0.021). Depicting a comprehensive landscape of the TME characteristics of gastric cancer may, therefore, help to interpret the responses of gastric tumors to immunotherapies and provide new strategies for the treatment of cancers.

Although most activating mutations of epidermal growth factor receptor (EGFR)-mutant non–small cell lung cancers (NSCLCs) are sensitive to available EGFR tyrosine kinase inhibitors (TKIs), a subset with alterations in exon 20 of EGFR and HER2 are intrinsically resistant and lack an effective therapy. We used in silico, in vitro, and in vivo testing to model structural alterations induced by exon 20 mutations and to identify effective inhibitors. 3D modeling indicated alterations restricted the size of the drug-binding pocket, limiting the binding of large, rigid inhibitors. We found that poziotinib, owing to its small size and flexibility, can circumvent these steric changes and is a potent inhibitor of the most common EGFR and HER2 exon 20 mutants. Poziotinib demonstrated greater activity than approved EGFR TKIs in vitro and in patient-derived xenograft models of EGFR or HER2 exon 20 mutant NSCLC and in genetically engineered mouse models of NSCLC. In a phase 2 trial, the first 11 patients with NSCLC with EGFR exon 20 mutations receiving poziotinib had a confirmed objective response rate of 64%. These data identify poziotinib as a potent, clinically active inhibitor of EGFR and HER2 exon 20 mutations and illuminate the molecular features of TKIs that may circumvent steric changes induced by these mutations.

Osimertinib was initially approved for T790M-positive non-small cell lung cancer (NSCLC) and, more recently, for first-line treatment of -mutant NSCLC. However, resistance mechanisms to osimertinib have been incompletely described. Using cohorts from The University of Texas MD Anderson Lung Cancer Moonshot GEMINI and Moffitt Cancer Center lung cancer databases, we collected clinical data for patients treated with osimertinib. Molecular profiling analysis was performed at the time of progression in a subset of the patients. In the 118 patients treated with osimertinib, 42 had molecular profiling at progression. T790M was preserved in 21 (50%) patients and lost in 21 (50%). EGFR C797 and L792 (26%) mutations were the most common resistance mechanism and were observed exclusively in T790M-preserved cases. MET amplification was the second most common alteration (14%). Recurrent alterations were observed in 22 genes/pathways, including PIK3CA, FGFR, and RET. Preclinical studies confirmed MET, PIK3CA, and epithelial-to-mesenchymal transition as potential resistance drivers. Alterations of cell-cycle genes were associated with shorter median progression-free survival (PFS, 4.4 vs. 8.8 months, = 0.01). In 76 patients with progression, osimertinib was continued in 47 cases with a median second PFS (PFS2) of 12.6 months; 21 patients received local consolidation radiation with a median PFS of 15.5 months. Continuation of osimertinib beyond progression was associated with a longer overall survival compared with discontinuation (11.2 vs. 6.1 months, = 0.02). Osimertinib resistance is associated with diverse, predominantly EGFR-independent genomic alterations. Continuation of osimertinib after progression, alone or in conjunction with radiotherapy, may provide prolonged clinical benefit in selected patients.