EMA Recommendation for the Pediatric Indications of Plerixafor (Mozobil) to Enhance Mobilization of Hematopoietic Stem Cells for Collection and Subsequent Autologous Transplantation in Children with Lymphoma or Malignant Solid Tumors.

On March 28, 2019, the Committee for Medicinal Products for Human Use adopted a positive opinion recommending the marketing authorization for the medicinal product plerixafor. The marketing authorization holder for this medicinal product is Genzyme Europe B.Th. The adoption was for an extension of the existing adult indication in combination with granulocyte colony-stimulating factor (G-CSF) to pediatric patients (aged 1 year to <18 years) to enhance mobilization of hematopoietic stem cells to the peripheral blood for collection and subsequent autologous transplantation in children with lymphoma or solid malignant tumors. This treatment is indicated either preemptively, when circulating stem cell count on the predicted day of collection after adequate mobilization with G-CSF (with or without chemotherapy) is expected to be insufficient with regard to desired hematopoietic stem cells yield, or in children who previously failed to collect sufficient hematopoietic stem cells. The efficacy and safety of plerixafor were evaluated in an open label, multicenter, phase I/II, dose-ranging, and randomized controlled study (DFI12860) in pediatric patients with solid tumors, including neuroblastoma, sarcoma, Ewing sarcoma, or lymphoma, who were eligible for autologous hematopoietic stem cell transplantation. Forty-five patients (aged 1 year to <18 years) were randomized, 2:1, using 0.24 mg/kg of plerixafor plus standard mobilization (G-CSF with or without chemotherapy) versus control (standard mobilization alone). The primary analysis showed that 80% of patients in the plerixafor arm experienced at least a doubling of the peripheral blood (PB) CD34+ count, observed from the morning of the day preceding the first planned apheresis to the morning prior to apheresis, versus 28.6% of patients in the control arm (p = .0019). The median increase in PB CD34+ cell counts from baseline to the day of apheresis was 3.2-fold in the plerixafor arm versus by 1.4-fold in the control arm. The observed safety profile in the pediatric population was consistent with that in adults, with adverse events mainly related to injection site reactions, hypokalemia, and increased blood bicarbonate. Importantly, plerixafor exposure did not seem to negatively affect transplant efficiency. This article summarizes the scientific review of the application leading to regulatory approval in the European Union. IMPLICATIONS FOR PRACTICE: This review of the marketing authorization of plerixafor will raise awareness of pediatric indication granted for this medicinal product.

Hemocompatibility assessment of two siRNA nanocarrier formulations.

PURPOSE: Since the discovery of RNAi and its therapeutic potential, carrier systems have been developed to deliver small RNAs (particularly siRNA) for modulation of gene expression at the post-transcriptional level. An important factor determining the fate and usability of these systems in vivo is interaction with blood components, blood cells, and the immune system. In this study, a lipid-based and a polymer-based carrier system containing siRNA have been investigated in vitro in terms of their hemocompatibility. METHODS: The nanocomplexes studied were Angiplex, a targeted lipid-based system, and pHPMA-MPPM polyplex, a formulation based on a cationic polymer. siVEGFR-2 was encapsulated in both carriers and activation of platelets, coagulation, and complement cascade as well as induction of platelet aggregation were evaluated in vitro. RESULTS: Both systems had been shown before to cause significant silencing in vitro. Our findings indicated that pHPMA-MPPM polyplex triggered high platelet activation and aggregation although it did not stimulate coagulation substantially. Angiplex, on the other hand, provoked insignificant activation and aggregation of platelets and activated coagulation minimally. Complement system activation by Angiplex was in general low but stronger than pHPMA-MPPM polyplex. CONCLUSIONS: Taken together, these in vitro assays may help the selection of suitable carriers for systemic delivery of siRNA in early preclinical investigations and reduce the use of laboratory animals significantly.

Anginex lipoplexes for delivery of anti-angiogenic siRNA.

Angiogenesis is one of the hallmarks of cancer which renders it an attractive target for therapy of malignancies. Tumor growth suppression can be achieved by inhibiting angiogenesis since it would deprive tumor cells of oxygen and vital nutrients. Activation of endothelial cells of tumor vasculature is the first step in angiogenesis which is mediated by various factors. One of the major triggers in this process is vascular endothelial growth factor (VEGF) which binds to VEGF receptors on endothelial cells of tumor vessels. This induces a series of signaling cascades leading to activation of cellular processes involved in angiogenesis, and therefore down-regulation of VEGF receptor-2 (VEGFR-2) expression seems a viable option to inhibit angiogenesis. In our investigations, this aim has been pursued by using siRNA interfering with the expression of VEGFR-2. Since the discovery of RNA interference (RNAi) as a gene regulation process, successful delivery of small non-coding RNA has presented itself as a major challenge. In the current study, we have characterized a galectin-1 targeted anginex-coupled lipoplex (Angiplex) containing siRNA against the gene of VEGFR-2 as an angiostatic therapeutic. Angiplex particles had a size of approximately 120 nm with a net negative charge and were stable in vitro. These particles were internalized in a specific manner by HUVECs compared to a non-targeted lipoplex system, and their uptake was higher than Lipofectamine 2000. Gene silencing efficiency of Angiplex was shown to be 61%.

Systemic miRNA-7 delivery inhibits tumor angiogenesis and growth in murine xenograft glioblastoma.

Tumor-angiogenesis is the multi-factorial process of sprouting of endothelial cells (EC) into micro-vessels to provide tumor cells with nutrients and oxygen. To explore miRNAs as therapeutic angiogenesis-inhibitors, we performed a functional screen to identify miRNAs that are able to decrease EC viability. We identified miRNA-7 (miR-7) as a potent negative regulator of angiogenesis. Introduction of miR-7 in EC resulted in strongly reduced cell viability, tube formation, sprouting and migration. Application of miR-7 in the chick chorioallantoic membrane assay led to a profound reduction of vascularization, similar to anti-angiogenic drug sunitinib. Local administration of miR-7 in an in vivo murine neuroblastoma tumor model significantly inhibited angiogenesis and tumor growth. Finally, systemic administration of miR-7 using a novel integrin-targeted biodegradable polymeric nanoparticles that targets both EC and tumor cells, strongly reduced angiogenesis and tumor proliferation in mice with human glioblastoma xenografts. Transcriptome analysis of miR-7 transfected EC in combination with in silico target prediction resulted in the identification of OGT as novel target gene of miR-7. Our study provides a comprehensive validation of miR-7 as novel anti-angiogenic therapeutic miRNA that can be systemically delivered to both EC and tumor cells and offers promise for miR-7 as novel anti-tumor therapeutic.