Failure of human rhombic lip differentiation underlies medulloblastoma formation

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain 1–4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage 5–8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL 9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage 3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES +KI67 + unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB

Prognostic Value of CD109+ Circulating Endothelial Cells in Recurrent Glioblastomas Treated with Bevacizumab and Irinotecan

<div><p>Background</p><p>Recent data suggest that circulating endothelial and progenitor cells (CECs and CEPs, respectively) may have predictive potential in cancer patients treated with bevacizumab, the antibody recognizing vascular endothelial growth factor (VEGF). Here we report on CECs and CEPs investigated in 68 patients affected by recurrent glioblastoma (rGBM) treated with bevacizumab and irinotecan and two Independent Datasets of rGBM patients respectively treated with bevacizumab alone (n=32, independent dataset A: IDA) and classical antiblastic chemotherapy (n=14, independent dataset B: IDB).</p> <p>Methods</p><p>rGBM patients with KPS ≥50 were treated until progression, as defined by MRI with RANO criteria. CECs expressing CD109, a marker of tumor endothelial cells, as well as other CEC and CEP subtypes, were investigated by six-color flow cytometry.</p> <p>Results</p><p>A baseline count of CD109+ CEC higher than 41.1/ml (1^st quartile) was associated with increased progression free survival (PFS; 20 versus 9 weeks, <i>P</i>=0.008) and overall survival (OS; 32 versus 23 weeks, <i>P</i>=0.03). Longer PFS (25 versus 8 weeks, <i>P</i>=0.02) and OS (27 versus 17 weeks, <i>P</i>=0.03) were also confirmed in IDA with CD109+ CECs higher than 41.1/ml but not in IDB. Patients treated with bevacizumab with or without irinotecan that were free from MRI progression after two months of treatment had significant decrease of CD109+ CECs: median PFS was 19 weeks; median OS 29 weeks. The presence of two non-contiguous lesions (distant disease) at baseline was an independent predictor of shorter PFS and OS (<i>P</i><0.001).</p> <p>Conclusions</p><p>Data encourage further studies on the predictive potential of CD109+ CECs in GBM patients treated with bevacizumab.</p> </div

Genetics of HUS: the impact of MCP, CFH, and IF mutations on clinical presentation, response to treatment, and outcome

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy with manifestations of hemolytic anemia, thrombocytopenia, and renal impairment. Genetic studies have shown that mutations in complement regulatory proteins predispose to non–Shiga toxin–associated HUS (non-Stx–HUS). We undertook genetic analysis on membrane cofactor protein (MCP), complement factor H (CFH), and factor I (IF) in 156 patients with non-Stx–HUS. Fourteen, 11, and 5 new mutational events were found in MCP, CFH, and IF, respectively. Mutation frequencies were 12.8%, 30.1%, and 4.5% for MCP, CFH, and IF, respectively. MCP mutations resulted in either reduced protein expression or impaired C3b binding capability. MCP-mutated patients had a better prognosis than CFH-mutated and nonmutated patients. In MCP-mutated patients, plasma treatment did not impact the outcome significantly: remission was achieved in around 90% of both plasma-treated and plasma-untreated acute episodes. Kidney transplantation outcome was favorable in patients with MCP mutations, whereas the outcome was poor in patients with CFH and IF mutations due to disease recurrence. This study documents that the presentation, the response to therapy, and the outcome of the disease are influenced by the genotype. Hopefully this will translate into improved management and therapy of patients and will provide the way to design tailored treatments

CEC evaluation by flow cytometry.

<p>A: Gate used to exclude cell fragments and debris. B: Gate made to identify CD45- cells. C: CD31 expression and Syto16 staining in CD45- cells. D: Negative control for E (CD31+ CD146+, CECs), F (CD31+ CD109+ CECs) and G (CD31-CD140b+, PPCs). E1: Distribution of viable, apoptotic, and necrotic CECs.</p

CECs, CD109+ CECs, CD45dimCD34+VEGFR2+ hp, CD140b+ PPCs before therapy and at 2 months.

<div><p>A: Counts of CECs, CD109+ CECs, CD45dimCD34+VEGFR2+ hp, CD140b+ PPCs before therapy and 2 months after treatment onset in patients responding to treatment with bevacizumab and irinotecan. B: Counts of CECs, CD109+ CECs, CD45dimCD34+VEGFR2+ hp, CD140b+ PPCs before therapy and 2 months after treatment onset in patients responding to treatment with bevacizumab alone (IDA).</p> <p>Boxes: the interquartile range; lines: location of first quartile, median, and third quartile. ○, outliers beyond the standard span. All P values were calculated by Wilcoxon test. Abbreviations: CECs, circulating endothelial cells; hp, hematopoietic progenitor cells; PPCs, progenitor perivascular cells; VEGFR, vascular endothelial growth factor receptor.</p></div

Correlation between baseline CD109+ CECs and PFS/OS in patients treated with bevacizumab+irinotecan or bevacizumab alone.

<p>Patients treated with bevacizumab and irinotecan and showing baseline CD109+ CEC count > 41.1/ml (1^st quartile) had increased PFS and OS (panels A); PFS was significantly increased also in patients belonging to IDA and baseline CD109+ CEC count over the 1^st quartile (panels B).</p

Progenitor cell evaluation by flow cytometry.

<p>A: Gate used to exclude cell fragments and debris. B: Gate made to include CD45- and CD45dim cells. C: Gate on Syto16+ 7AAD+ cells. D: Identification of 2 different populations: CD45-CD34+ + and CD133-VEGFR2- (D1), and CD45dimCD34+ and CD133+ cells (D2).</p