Enhanced brain entry of checkpoint-inhibitory therapeutic antibodies facilitated by intraarterial NEO100 in mouse models of brain-localized malignancies.

OBJECTIVE: Immune checkpoint-inhibitory therapeutic antibodies have shown striking activity against several types of cancers but are less effective against brain-localized malignancies, in part due to the protective effect of the blood-brain barrier (BBB). The authors hypothesized that intraarterial (IA) delivery of a novel compound, NEO100, has the potential to safely and reversibly open the BBB to enable brain-targeted therapeutic activity of checkpoint-inhibitory antibodies. METHODS: Immunocompetent mice with syngeneic glioblastoma or melanoma cells implanted into their brains were subjected to a single IA injection of NEO100 to open their BBB. One dose of murine anti-PD-1/PD-L1 antibody was either coinjected with NEO100 or separately injected intravenously. Brain penetration of these antibodies and levels of CD8+ T cell infiltrate into the tumor microenvironment were quantitated and animal survival was monitored. RESULTS: IA NEO100 enabled the increased accumulation of checkpoint-inhibitory antibodies in the brain, along with greater numbers of T cells. In both malignancy models, a single intervention of IA NEO100 combined with antibody resulted in the long-term survival of animals. Antibody treatment in the absence of NEO100 was far less effective. CONCLUSIONS: BBB opening by IA NEO100 facilitates brain tumor access by checkpoint-inhibitory antibodies and enables their therapeutic activity, along with increased levels of T-cell recruitment.

Enhanced brain delivery and therapeutic activity of trastuzumab after blood-brain barrier opening by NEO100 in mouse models of brain-metastatic breast cancer.

BACKGROUND: The antitumor efficacy of human epidermal growth factor receptor 2 (HER2)-targeted therapies, such as humanized monoclonal antibody trastuzumab (Herceptin®, Roche), in patients with breast-to-brain cancer metastasis is hindered by the low permeability of the blood-brain barrier (BBB). NEO100 is a high-purity version of the natural monoterpene perillyl alcohol, produced under current good manufacturing practice (cGMP) regulations, that was shown previously to reversibly open the BBB in rodent models. Here we investigated whether NEO100 could enable brain entry of trastuzumab to achieve greater therapeutic activity. METHODS: An in vitro BBB, consisting of human astrocytes and brain endothelial cells, was used to determine trastuzumab penetration in the presence or absence of NEO100. For in vivo studies, we administered intravenous (IV) trastuzumab or the trastuzumab-drug conjugate ado-trastuzumab emtansine (T-DM1; Kadcyla®, Roche), to mouse models harboring intracranial HER2+ breast cancer, with or without BBB opening via IA NEO100. Brain and tumor tissues were examined for the presence of trastuzumab and infiltration of immune cells. Therapeutic impact was evaluated based on overall survival. RESULTS: NEO100 greatly increased trastuzumab penetration across an in vitro BBB. In vivo, IA NEO100-mediated BBB opening resulted in brain tumor-selective accumulation of trastuzumab, without detectable presence in normal brain tissue, along with increased presence of immune cell populations. IV delivery of trastuzumab or T-DM1 achieved significantly greater overall survival of tumor-bearing mice when combined with IA NEO100. CONCLUSION: IA NEO100 facilitates brain tumor entry of trastuzumab and T-DM1 and significantly enhances their therapeutic efficacy, along with increased antibody-dependent immune cell recruitment.