Anti-WT1 (full length) polyclonal antibody

Objectives Vaccines that prime Wilms' tumor 1 (WT1)-specific CD8(+)T cells are attractive cancer immunotherapies. However, immunogenicity and clinical response rates may be enhanced by delivering WT1 to CD141(+)dendritic cells (DCs). The C-type lectin-like receptor CLEC9A is expressed exclusively by CD141(+)DCs and regulates CD8(+)T-cell responses. We developed a new vaccine comprising a human anti-CLEC9A antibody fused to WT1 and investigated its capacity to target human CD141(+)DCs and activate naive and memory WT1-specific CD8(+)T cells. Methods WT1 was genetically fused to antibodies specific for human CLEC9A, DEC-205 or beta-galactosidase (untargeted control). Activation of WT1-specific CD8(+)T-cell lines following cross-presentation by CD141(+)DCs was quantified by IFN gamma ELISPOT. Humanised mice reconstituted with human immune cell subsets, including a repertoire of naive WT1-specific CD8(+)T cells, were used to investigate naive WT1-specific CD8(+)T-cell priming. Results The CLEC9A-WT1 vaccine promoted cross-presentation of WT1 epitopes to CD8(+)T cells and mediated priming of naive CD8(+)T cells more effectively than the DEC-205-WT1 and untargeted control-WT1 vaccines. Conclusions Delivery of WT1 to CD141(+)DCs via CLEC9A stimulates CD8(+)T cells more potently than either untargeted delivery or widespread delivery to all Ag-presenting cells via DEC-205, suggesting that cross-presentation by CD141(+)DCs is sufficient for effective CD8(+)T-cell priming in humans. The CLEC9A-WT1 vaccine is a promising candidate immunotherapy for malignancies that express WT1.

The group of CNS mesenchymal (non-meningothelial) and primary glial/neuronal tumors in association with EWSR1-non-ETS rearrangements comprises a growing spectrum of entities, mostly reported in isolation with incomplete molecular profiling. Archival files from three pediatric institutions were queried for unusual cases of pediatric (<= 21 years) CNS EWSR1-rearranged tumors confirmed by at least one molecular technique. Extra-axial tumors and cases with a diagnosis of Ewing sarcoma (EWSR1-ETS family fusions) were excluded. Additional studies, including anchored multiplex-PCR with next-generation sequencing and DNA methylation profiling, were performed as needed to determine fusion partner status and brain tumor methylation class, respectively. Five cases (median 17 years) were identified (M:F of 3:2). Location was parenchymal (n = 3) and undetermined (n = 2) with topographic distributions including posterior fossa (n = 1), frontal (n = 1), temporal (n = 1), parietal (n = 1) and occipital (n = 1) lobes. Final designation with fusion findings included desmoplastic small round cell tumor (EWSR1-WT1; n = 1) and tumors of uncertain histogenesis (EWSR1-CREM, n = 1; EWSR1-CREB1, n = 1; EWSR1-PLAGL1, n = 1; and EWSR1-PATZ1, n = 1). Tumors showed a wide spectrum of morphology and biologic behavior. For EWSR1-CREM, EWSR1-PLAGL1 and EWSR1-PATZ1 tumors, no significant methylation scores were reached in the known brain tumor classes. Available outcome (4/5) was reported as favorable (n = 2) and unfavorable (n = 2) with a median follow-up of 30 months. In conclusion, we describe five primary EWSR1-non-ETS fused CNS tumors exhibiting morphologic and biologic heterogeneity and we highlight the clinical importance of determining specific fusion partners to improve diagnostic accuracy, treatment and monitoring. Larger prospective clinicopathological and molecular studies are needed to determine the prognostic implications of histotypes, anatomical location, fusion partners, breakpoints and methylation profiles in patients with these rare tumors.