Targeting lipid nanoparticles to the blood-brain barrier to ameliorate acute ischemic stroke.

Effective delivery of mRNA or small molecule drugs to the brain is a significant challenge in developing treatment for acute ischemic stroke (AIS). To address the problem, we have developed targeted nanomedicine to increase drug concentrations in endothelial cells of the blood-brain barrier (BBB) of the injured brain. Inflammation during ischemic stroke causes continuous neuronal death and an increase in the infarct volume. To enable targeted delivery to the inflamed BBB, we conjugated lipid nanocarriers (NCs) with antibodies that bind cell adhesion molecules expressed at the BBB. In the transient middle cerebral artery occlusion mouse model, NCs targeted to vascular cellular adhesion molecule-1 (VCAM) achieved the highest level of brain delivery, nearly two orders of magnitude higher than untargeted ones. VCAM-targeted lipid nanoparticles with luciferase-encoding mRNA and Cre-recombinase showed selective expression in the ischemic brain. Anti-inflammatory drugs administered intravenously after ischemic stroke reduced cerebral infarct volume by 62% (interleukin-10 mRNA) or 35% (dexamethasone) only when they were encapsulated in VCAM-targeted NCs. Thus, VCAM-targeted lipid NCs represent a new platform for strongly concentrating drugs within the compromised BBB of penumbra, thereby ameliorating AIS.

Cell Context is the third axis of synergy for the combination of ATR inhibition and cisplatin in Ewing sarcoma.

PURPOSE: The importance of cellular context to the synergy of DNA Damage Response (DDR) targeted agents is important for tumors with mutations in DDR pathways, but less well-established for tumors driven by oncogenic transcription factors. In this study, we exploit the widespread transcriptional dysregulation of the EWS-FLI1 transcription factor to identify an effective DDR targeted combination therapy for Ewing Sarcoma (ES). EXPERIMENTAL DESIGN: We used matrix drug screening to evaluate synergy between a DNA-PK inhibitor (M9831) or an ATR inhibitor (berzosertib) and chemotherapy. The combination of berzosertib and cisplatin was selected for broad synergy, mechanistically evaluated for ES selectivity, and optimized for in vivo schedule. RESULTS: Berzosertib combined with cisplatin demonstrates profound synergy in multiple ES cell lines at clinically achievable concentrations. The synergy is due to loss of expression of the ATR downstream target CHEK1, loss of cell cycle checkpoints, and mitotic catastrophe. Consistent with the goals of the project, EWS-FLI1 drives the expression of CHEK1 and five other ATR pathway members. The loss of CHEK1 expression is not due to transcriptional repression and instead caused by degradation coupled with suppression of protein translation. The profound synergy is realized in vivo with a novel optimized schedule of this combination in subsets of ES models leading to durable complete responses in 50% of animals bearing two different ES xenografts. CONCLUSION: These data exploit EWS-FLI1 driven alterations in cell context to broaden the therapeutic window of berzosertib and cisplatin to establish a promising combination therapy and a novel in vivo schedule.