The Tol2 transposon system mediates the genetic engineering of T-cells with CD19-specific chimeric antigen receptors for B-cell malignancies

Engineered T-cell therapy using a CD19-specific chimeric antigen receptor (CD19-CAR) is a promising strategy for the treatment of advanced B-cell malignancies. Gene transfer of CARs to T-cells has widely relied on retroviral vectors, but transposon-based gene transfer has recently emerged as a suitable nonviral method to mediate stable transgene expression. The advantages of transposon vectors compared with viral vectors include their simplicity and cost-effectiveness. We used the Tol2 transposon system to stably transfer CD19-CAR into human T-cells. Normal human peripheral blood lymphocytes were co-nucleofected with the Tol2 transposon donor plasmid carrying CD19-CAR and the transposase expression plasmid and were selectively propagated on NIH3T3 cells expressing human CD19. Expanded CD3(+) T-cells with stable and high-level transgene expression (~95%) produced interferon-γ upon stimulation with CD19 and specifically lysed Raji cells, a CD19(+) human B-cell lymphoma cell line. Adoptive transfer of these T-cells suppressed tumor progression in Raji tumor-bearing Rag2(-/-)γc(-/-) immunodeficient mice compared with control mice. These results demonstrate that the Tol2 transposon system could be used to express CD19-CAR in genetically engineered T-cells for the treatment of refractory B-cell malignancies.

Islet cell tumors of the pancreas: the medical oncologist's perspective

Islet cell tumors of the pancreas are rare, indolent, neuroendocrine tumors. Approximately 50% of the patients diagnosed with these tumors present with symptoms related to various biologically active hormones that are secreted by these neoplasms. Currently, the only curative treatment for islet cell tumors is complete surgical resection. Management of metastatic disease is conservative. Initial treatment of these tumors includes expectant observation and medical management of symptoms with clinical monitoring and serial CT scans to assess tumor growth. Patients with rapidly progressive disease, with local symptoms caused by tumor bulk, or with uncontrolled symptoms related to hormone secretion require more aggressive medical or surgical intervention. The somatostatin analogue octreotide may help control hormone secretion and stabilize tumor growth. Patients refractory to octreotide with tumor predominantly in the liver are potential candidates for mechanical ablative techniques, such as hepatic arterial embolization. Radiofrequency ablation and cryosurgical techniques may also be useful, although specific data are limited. Surgical resection of metastatic disease may offer palliative relief of symptoms related to hormone secretion in carefully selected patients. Chemotherapy may be used for palliation when ablative techniques have failed or when significant extrahepatic disease is present. Streptozicin-based combinations remain the first line standard, but major objective responses are less common than had been previously thought. Because of the overall modest success of current chemotherapeutic regimens, patients with advanced disease in need of treatment should be encouraged to enroll in clinical trials testing newer antineoplastic agents or newer treatment strategies.