MEVITEM—a phase I/II trial of vismodegib + temozolomide vs temozolomide in patients with recurrent/refractory medulloblastoma with Sonic Hedgehog pathway activation

BackgroundVismodegib specifically inhibits Sonic Hedgehog (SHH). We report results of a phase I/II evaluating vismodegib + temozolomide (TMZ) in immunohistochemically defined SHH recurrent/refractory adult medulloblastoma.MethodsTMZ-naïve patients were randomized 2:1 to receive vismodegib + TMZ (arm A) or TMZ (arm B). Patients previously treated with TMZ were enrolled in an exploratory cohort of vismodegib (arm C). If the safety run showed no excessive toxicity, a Simon’s 2-stage phase II design was planned to explore the 6-month progression-free survival (PFS-6). Stage II was to proceed if arm A PFS-6 was ≥3/9 at the end of stage I.ResultsA total of 24 patients were included: arm A (10), arm B (5), and arm C (9). Safety analysis showed no excessive toxicity. At the end of stage I, the PFS-6 of arm A was 20% (2/10 patients, 95% unilateral lower confidence limit: 3.7%) and the study was prematurely terminated. The overall response rates (ORR) were 40% (95% CI, 12.2-73.8) and 20% (95% CI, 0.5-71.6) in arm A and B, respectively. In arm C, PFS-6 was 37.5% (95% CI, 8.8-75.5) and ORR was 22.2% (95% CI, 2.8-60.0). Among 11 patients with an expected sensitivity according to new generation sequencing (NGS), 3 had partial response (PR), 4 remained stable disease (SD) while out of 7 potentially resistant patients, 1 had PR and 1 SD.ConclusionThe addition of vismodegib to TMZ did not add toxicity but failed to improve PFS-6 in SHH recurrent/refractory medulloblastoma. Prediction of sensitivity to vismodegib needs further refinements.     

Smoothened (SMO) receptor mutations dictate resistance to?vismodegib in basal cell carcinoma

Basal cell carcinomas (BCCs) and a subset of medulloblastomas are characterized by loss‐of‐function mutations in the tumor suppressor gene, PTCH1. PTCH1 normally functions by repressing the activity of the Smoothened (SMO) receptor. Inactivating PTCH1 mutations result in constitutive Hedgehog pathway activity through uncontrolled SMO signaling. Targeting this pathway with vismodegib, a novel SMO inhibitor, results in impressive tumor regression in patients harboring genetic defects in this pathway. However, a secondary mutation in SMO has been reported in medulloblastoma patients following relapse on vismodegib to date. This mutation preserves pathway activity, but appears to confer resistance by interfering with drug binding.Here we report for the first time on the molecular mechanisms of resistance to vismodegib in two BCC cases. The first case, showing progression after 2 months of continuous vismodegib (primary resistance), exhibited the new SMO G497W mutation. The second case, showing a complete clinical response after 5 months of treatment and a subsequent progression after 11 months on vismodegib (secondary resistance), exhibited a PTCH1 nonsense mutation in both the pre‐ and the post‐treatment specimens, and the SMO D473Y mutation in the post‐treatment specimens only. In silico analysis demonstrated that SMOG497W undergoes a conformational rearrangement resulting in a partial obstruction of the protein drug entry site, whereas the SMO D473Y mutation induces a direct effect on the binding site geometry leading to a total disruption of a stabilizing hydrogen bond network. Thus, the G497W and D473Y SMO mutations may represent two different mechanisms leading to primary and secondary resistance to vismodegib, respectively.     

支持向量机基础上的银屑病辅助诊断方法研究

介绍基于支持向量机的银屑病辅助诊断方法实现流程，包括数据收集和预处理、构建数据库群、特征提取、建立基于支持向量机的辅助诊断模型。通过实验验证该方法的有效性，其诊断精度较高，可以为银屑病数据分析、疾病预防提供技术支持。     

SMO基因突变在成釉细胞瘤中的研究进展

SMO基因编码的蛋白质SMO是sonic hedgehog(SHH)信号通路中至关重要的信号转换器。SHH信号通路与多种人类肿瘤的发生、发展密切相关,异常激活的SHH信号通路通过影响细胞的增殖、分化和凋亡,导致肿瘤发生。研究发现在成釉细胞瘤中,SMO基因是除BRAF基因之外第二常见突变的基因,其较高的突变率使得SMO基因成为成釉细胞瘤分子病理研究领域中的热点。现在已有大量的研究证实,SMO基因突变与成釉细胞瘤的临床特征(如发病部位、组织学、年龄和预后等)有关,这些研究结果为成釉细胞瘤的靶向治疗提供了新的治疗思路,本文就SMO基因突变在成釉细胞瘤中的研究进展及其潜在的临床意义进行综述。     

Effect of Mono-2-ethyhexyl Phthalate on DNA Methylation in Human Prostate Cancer LNCaP Cells

Objective To evaluate whether mono(2‐ethylhexyl) phthalate(MEHP) affects genomic DNA methylation and the methylation status of some specific genes such as patched gene(PTCH) and smoothened gene(SMO) in LNCaP cells. Methods LNCaP cells were treated with MEHP(0, 1, 5, 10, and 25 μmol/L) for 3 days. An ELISA assay was preformed to detect genomic methylation, including 5‐methylcytosine(5‐mC) and 5‐hydroxymethylcytosine(5‐hmC) content. A pyrosequencing assay was applied to assess DNA methylation in PTCH and SMO gene promoters. The correlation between DNA methylation and gene expression was assessed. Results The proportion of cytosines with 5‐mC methylation in LNCaP cells was significantly decreased by MEHP(1, 5, 10, and 25 μmol/L) in a dose‐dependent manner(P 0.01). For genes in the Hedgehog pathway, there was no significant MEHP concentration‐dependent difference in the DNA methylation of PTCH and SMO. Conclusion MEHP might affect the progression of prostate cancer through its effect on global DNA methylation.     

SMO特异性siRNA慢病毒载体的筛选构建

目的构建特异性沉默SMO基因的重组慢病毒载体,筛选对T293细胞SMO基因表达抑制效率最高的siRNA。方法根据SMO基因信息,设计了4个小干扰序列和1个阴性对照序列,利用慢病毒质粒载体pGCSIL-GFP构建了5个重组质粒。用脂质体将重组慢病毒载体转染293T细胞后,Western blot检测沉默效率,从中筛选沉默效率高的质粒载体进行慢病毒颗粒大量包装。结果测序结果证明4个重组慢病毒质粒载体pGCSIL-GFP-721、pGCSIL-GFP-722、pGCSIL-GFP-723、pGCSIL-GFP-724的插入序列完全正确,重组慢病毒载体转染293T细胞后,Western blotting证实重组慢病毒质粒载体pGCSIL-GFP-723的干扰效率最高。包装获得Lv-SIL-SMO723慢病毒颗粒。结论成功筛选获得特异性抑制SMO的siRNA,成功构建了特异性沉默SMO基因慢病毒载体,其产生的慢病毒颗粒能高效特异地沉默SMO基因,为进一步应用奠定基础。