Purpose We evaluated the uptake of angiopep-2 paclitaxel conjugate, ANG1005, into brain and brain metastases of breast cancer in rodents. Most anticancer drugs show poor delivery to brain tumors due to limited transport across the blood-brain barrier (BBB). To overcome this, a 19-amino acid peptide (angiopep-2) was developed that binds to low density lipoprotein receptor-related protein (LRP) receptors at the BBB and has the potential to deliver drugs to brain by receptor-mediated transport. Methods The transfer coefficient (Kin) for brain influx was measured by in situ rat brain perfusion. Drug distribution was determined at 30 min after i.v. injection in mice bearing intracerebral MDA-MB-231BR metastases of breast cancer. Results The BBB Kin for 125I-ANG1005 uptake (7.3 ± 0.2 × 10−3 mL/s/g) exceeded that for 3H-paclitaxel (8.5 ± 0.5 × 10−5) by 86 fold. Over 70% of 125I-ANG1005 tracer stayed in brain after capillary depletion or vascular washout. Brain 125I-ANG1005 uptake was reduced by unlabeled angiopep-2 vector and by LRP ligands, consistent with receptor transport. In vivo uptake of 125I-ANG1005 into vascularly corrected brain and brain metastases exceeded that of 14C-paclitaxel by 4–54 fold. Conclusions The results demonstrate that ANG1005 shows significantly improved delivery to brain and brain metastases of breast cancer compared to free paclitaxel.

Two of the biochemical features of Alzheimers disease (AD) that contribute to neurodegeneration are intracellular oxidative stress and elevated levels of trace metal ions, especially Fe III , Cu II , and Zn II . [1] Both are factors involved in formation of the histological features in the brain used typically for postmortem diagnosis of AD, namely b-amyloid (Ab) plaques and neurofibrillary tangles. Therapeutic interventions under current investigation elsewhere include clioquinol [2] and desferrioxamine, [3] which are metal chelators that target elevated trace-metal ions in the brain, although neither are intended to affect oxidative stress directly and nor are they targeted to the brain. Antioxidant supplements have been studied separately as palliative-only measures for alleviation of the symptoms of AD.[4]Herein, we present for the first time a trifunctional approach to AD therapy. Modified and functionalized bidentate hydroxypyridinone pro-ligands (Scheme 1) address both the metal-ion and the oxidative imbalances inherent in AD while incorporating a glucose-receptor targeting feature.These prodrugs are designed to cross the blood-brain barrier (BBB), lose the pendant carbohydrate by enzymatic cleavage, passivate excess metal ions in the brain, and also protect neuronal cells against reactive oxygen species (ROS). Each of these functionalities has been demonstrated, thereby establishing the trifunctional principle as a valid goal in AD therapy. The prodrug strategy solves the potential problem of premature metal binding by using carbohydrates as both masking and directing substituents. In the context of increasing empirical support for re-establishing normal metal-ion homeostasis in neurodegenerative diseases, including AD, the trifunctional approach permits selective, tissue-dependent metal binding as a tailor-made, biologically compatible therapy.To demonstrate the utility of this approach, a series of assays on prototype compounds have been undertaken, including both in vitro and in vivo studies. This strategy is aimed at reducing neurodegeneration from oxidative stress; by passivating the pro-oxidant metal ions Fe III and Cu II , the production of ROS can be expected to be lower. By changing the R group on the pyridinone ring, the aqueous solubility, lipophilicity, and BBB permeability can be modified. Prodrug hydroxy (OH) groups have been elaborated by glycosylation (Scheme 1 b) such that, after enzymatic deprotection, the free ligands will have ring OH groups available that can either efficiently trap radicals or bind metal complexes (Scheme 1 a). Removing metal ions that promote Ab aggregation, such as Cu II and Zn II, also serves to prevent or reverse Scheme 1. Hydroxypyridinones: a) nonglycosylated pro-ligands and b) their glycosylated prodrug forms designed for metal passivation in the brain as a therapeutic intervention in Alzheimer's disease (AD).

Purpose: As chemotherapy and molecular therapy improve the systemic survival of breast cancer patients, the incidence of brain metastases increases. Few therapeutic strategies exist for the treatment of brain metastases because the blood-brain barrier severely limits drug access. We report the pharmacokinetic, efficacy, and mechanism of action studies for the histone deactylase inhibitor vorinostat (suberoylanilide hydroxamic acid) in a preclinical model of brain metastasis of triple-negative breast cancer. Experimental Design: The 231-BR brain trophic subline of the MDA-MB-231 human breast cancer cell line was injected into immunocompromised mice for pharmacokinetic and metastasis studies. Pharmacodynamic studies compared histone acetylation, apoptosis, proliferation, and DNA damage in vitro and in vivo. Results: Following systemic administration, uptake of [ 14 C]vorinostat was significant into normal rodent brain and accumulation was up to 3-fold higher in a proportion of metastases formed by 231-BR cells. Vorinostat prevented the development of 231-BR micrometastases by 28% (P = 0.017) and large metastases by 62% (P < 0.0001) compared with vehicle-treated mice when treatment was initiated on day 3 post-injection. The inhibitory activity of vorinostat as a single agent was linked to a novel function in vivo: induction of DNA double-strand breaks associated with the down-regulation of the DNA repair gene Rad52. Conclusions:We report the first preclinical data for the prevention of brain metastasis of triple-negative breast cancer. Vorinostat is brain permeable and can prevent the formation of brain metastases by 62%. Its mechanism of action involves the induction of DNA double-strand breaks, suggesting rational combinations with DNA active drugs or radiation. (Clin Cancer Res 2009;15(19):6148-57) Significant advances have been made in the treatment of primary breast cancer; one of the unfortunate complications of this progress is an increase in the incidence of brain metastases (reviewed in refs. 1, 2). Combinations of cytotoxic and targeted therapies have afforded metastatic breast cancer patients' clinical responses or stable disease, but the poor penetration of these drugs into the brain and leptomeninges creates a "sanctuary site" for recurrence. With an increased number of metastatic breast cancer patients having stable disease or responding to treatment systemically when they develop brain metastases,