In vivo CRISPR/Cas9 targeting of fusion oncogenes for selective elimination of cancer cells

Fusion oncogenes (FOs) are common in many cancer types and are powerful drivers of tumor development. Because their expression is exclusive to cancer cells and their elimination induces cell apoptosis in FO-driven cancers, FOs are attractive therapeutic targets. However, specifically targeting the resulting chimeric products is challenging. Based on CRISPR/Cas9 technology, here we devise a simple, efficient and non-patient-specific gene-editing strategy through targeting of two introns of the genes involved in the rearrangement, allowing for robust disruption of the FO specifically in cancer cells. As a proof-of-concept of its potential, we demonstrate the efficacy of intron-based targeting of transcription factors or tyrosine kinase FOs in reducing tumor burden/mortality in in vivo models. The FO targeting approach presented here might open new horizons for the selective elimination of cancer cells.

In vivo CRISPR/Cas9 targeting of fusion oncogenes for selective elimination of cancer cells

Fusion oncogenes (FOs) are common in many cancer types and are powerful drivers of tumor development. Because their expression is exclusive to cancer cells and their elimination induces cell apoptosis in FO-driven cancers, FOs are attractive therapeutic targets. However, specifically targeting the resulting chimeric products is challenging. Based on CRISPR/Cas9 technology, here we devise a simple, efficient and non-patient-specific gene-editing strategy through targeting of two introns of the genes involved in the rearrangement, allowing for robust disruption of the FO specifically in cancer cells. As a proof-of-concept of its potential, we demonstrate the efficacy of intron-based targeting of transcription factors or tyrosine kinase FOs in reducing tumor burden/mortality in in vivo models. The FO targeting approach presented here might open new horizons for the selective elimination of cancer cells.

Optimizing the storage of chemotherapeutics for ophthalmic oncology: stability of topotecan solution for intravitreal injection

BACKGROUND

. Intravitreal administration of topotecan shows activity against tumor vitreous seeding in the conservative treatment of retinoblastoma, a malignant tumor originated in the retina of small children. Adequate storage of the intravitreal topotecan solution would allow immediate availability for patients at health care institutions. The goal of the work was to address the stability of the intravitreal topotecan formulation upon reconstitution.

MATERIALS AND METHODS

. Intravitreal topotecan solutions were reconstituted (at a concentration of 0.2 mg topotecan in 1 mL saline solution vehicle, aliquoted in 1 mL plastic syringes) and stored either frozen or at room temperature for different times. Topotecan content was analyzed at time zero and at different conditions using a high performance liquid chromatography method to quantify topotecan lactone (active) and to detect its pH-dependent hydrolysis product, the open carboxylate.

RESULTS

. We found that intravitreal topotecan syringes remained stable at room temperature at least for 24 h, at least for 167 days upon stored frozen at -20°C, and up to 8 h after thawing at day 6. The degradation carboxylate product did not appear in the analyzed thawed samples during the whole study.

CONCLUSIONS

. This study confirms the stability of frozen intravitreal topotecan syringes and will help optimize the use of this chemotherapy modality at institutions with low resources. Storage of aliquots will also help reduce personnel exposure to chemotherapy at hospital pharmacies.

Translational Pharmacokinetic-Pharmacodynamic Modeling and Simulation: Optimizing 5-Fluorouracil Dosing in Children With Pediatric Ependymoma

We previously investigated novel therapies for pediatric ependymoma and found 5‐fluorouracil (5‐FU) i.v. bolus increased survival in a representative mouse model. However, without a quantitative framework to derive clinical dosing recommendations, we devised a translational pharmacokinetic‐pharmacodynamic (PK‐PD) modeling and simulation approach. Results from our preclinical PK‐PD model suggested tumor concentrations exceeded the 1‐hour target exposure (in vitro IC₉₀), leading to tumor growth delay and increased survival. Using an adult population PK model, we scaled our preclinical PK‐PD model to children. To select a 5‐FU dosage for our clinical trial in children with ependymoma, we simulated various 5‐FU dosages for tumor exposures and tumor growth inhibition, as well as considering tolerability to bolus 5‐FU administration. We developed a pediatric population PK model of bolus 5‐FU and simulated tumor exposures for our patients. Simulations for tumor concentrations indicated that all patients would be above the 1‐hour target exposure for antitumor effect.

Cell migration in paediatric glioma; characterisation and potential therapeutic targeting

BACKGROUND

Paediatric high grade glioma (pHGG) and diffuse intrinsic pontine glioma (DIPG) are highly aggressive brain tumours. Their invasive phenotype contributes to their limited therapeutic response, and novel treatments that block brain tumour invasion are needed.

METHODS

Here, we examine the migratory characteristics and treatment effect of small molecule glycogen synthase kinase-3 inhibitors, lithium chloride (LiCl) and the indirubin derivative 6-bromoindirubin-oxime (BIO), previously shown to inhibit the migration of adult glioma cells, on two pHGG cell lines (SF188 and KNS42) and one patient-derived DIPG line (HSJD-DIPG-007) using 2D (transwell membrane, immunofluorescence, live cell imaging) and 3D (migration on nanofibre plates and spheroid invasion in collagen) assays.

RESULTS

All lines were migratory, but there were differences in morphology and migration rates. Both LiCl and BIO reduced migration and instigated cytoskeletal rearrangement of stress fibres and focal adhesions when viewed by immunofluorescence. In the presence of drugs, loss of polarity and differences in cellular movement were observed by live cell imaging.

CONCLUSIONS

Ours is the first study to demonstrate that it is possible to pharmacologically target migration of paediatric glioma in vitro using LiCl and BIO, and we conclude that these agents and their derivatives warrant further preclinical investigation as potential anti-migratory therapeutics for these devastating tumours.

Adjuvant activity of polymer microparticles and Montanide ISA 720 on immune responses to Plasmodium falciparum MSP2 long synthetic peptides in mice

The purpose of this work was to test the immunogenicity in C57BL mice of two synthetic peptides derived from the constant region of 3D7 and FC27 Plasmodium falciparum MSP2 dimorphic proteins, either microencapsulated into poly-lactide-co-glycolide acid microparticles (PLGA MP) or delivered with the human compatible adjuvant Montanide ISA 720 for comparison. Potent and prolonged antibody responses were obtained for both peptides by using PLGA MP formulations after subcutaneous or intradermal injections. As compared to the subcutaneous route of immunization, the intradermal route induced greater immune responses. Montanide adjuvant was effective in eliciting antibodies against the 3D7 peptide but not against the FC27 peptide. Peptide-specific cytophilic antibodies (IgG2a) were detected after boosting with homologous peptide for all vaccine formulations. MP formulations elicited a lower IgE secretion as compared to that observed for both Montanide formulated vaccines. Our results demonstrate the ability of the polymer microparticles to overcome the lack of immunogenicity of FC27 MSP2 peptide in C57BL mice and their potential to induce desirable immune responses against malaria.

Biocompatibility Evaluation of Different Alginates and Alginate-Based Microcapsules

Biocompatibility of biomaterials and biomaterial-based medical devices is a critical issue for the long-term function on multiple therapeutic systems. In the past few years, there has been an increasing interest in producing more biocompatible biomaterials and in developing novel assays to analyze the quality of the products. In this study, a battery of in vitro techniques to assess the biocompatibility of alginates with different compositions and purities and alginate-based microcapsules is presented. Study of the protein and polyphenol content of the alginates revealed clear differences between the nonpurified and the purified alginates. A similar behavior was observed when the mitogenic activity and the tumor necrosis factor-alphasecretion induced by the alginates were assessed. Interestingly, when the latter two techniques were adapted to evaluate the different alginate microcapsules, a correlation with the results obtained for the alginate samples was observed. These results reinforce the idea of using the full battery of assays here reported to screen alginates and alginate-based microcapsules before implantation.

Potent, long lasting systemic antibody levels and mixed Th1/Th2 immune response after nasal immunization with malaria antigen loaded PLGA microparticles

The immunogenicity of the synthetic malaria vaccine SPf66 has been recently improved by the application of new adjuvants as QS-21 saponin or poly-D,L-lactide-co-glycolide (PLGA) polymers. The search for less invasive administration routes made us test the immunogenicity of SPf66-loaded microparticles by the nasal route in Balb/c mice. We report here that the intranasal administration of the adequate PLGA vaccine formulations greatly improves and maintains higher antibody levels compared to the conventional alum adjuvant and to the administration of the particles by other routes (subcutaneous, oral). Systemic immune responses were characterized as mixed Th1/Th2-type: IFN-gamma and IgG2a isotype were found as signs of Th1 activation, whilst IgE and IgG1 secretions indicate Th2 response. Since both types of response have been associated to protective immunity in malaria, we postulate that this new approach supposes an advantage over the traditional adjuvants and routes.

Immune response after oral administration of the encapsulated malaria synthetic peptide SPf66

The synthetic peptide SPf66 adsorbed on alum is one of the few Plasmodium falciparum vaccines which have been tested in field trials. We previously reported that subcutaneous administration of SPf66 loaded PLGA microparticles (MP) enhances the antibody response to this antigen compared to the conventional alum formulation. We now evaluate the suitability of polymeric formulations to obtain systemic immune responses by gastric intubation of Balb/c mice. Formulations composed of 1:1 mixtures of PLGA 50:50 and 75:25 (lactic:glycolic) microparticles were administered by the oral route, and when animals were boosted 3 weeks later significant systemic IgG antibody responses were elicited, comparable to alum triple shot and superior to the aqueous vaccine given by the oral route. The finding of IgG2a isotype for PLGA-vaccinated mice compared to the absent levels of this isotype for the alum-vaccinated group could be interpreted as a sign of Th1-like immune response and cellular immune response activation. Our results confirm that using the appropriate schedule the oral administration of PLGA particles is suitable to obtain systemic immune responses to the carried antigen.