Jean-Christophe Currie

Involvement of the low‐density lipoprotein receptor‐related protein in the transcytosis of the brain delivery vector Angiopep‐2

The blood–brain barrier (BBB) restricts the entry of proteins as well as potential drugs to cerebral tissues. We previously reported that a family of Kunitz domain‐derived peptides called Angiopeps can be used as a drug delivery system for the brain. Here, we further characterize the transcytosis ability of these peptides using an in vitro model of the BBB and in situ brain perfusion. These peptides, and in particular Angiopep‐2, exhibited higher transcytosis capacity and parenchymal accumulation than do transferrin, lactoferrin, and avidin. Angiopep‐2 transport and accumulation in brain endothelial cells were unaffected by the P‐glycoprotein inhibitor, cyclosporin A, indicating that this peptide is not a substrate for the efflux pump P‐glycoprotein. However, competition studies show that activated α2‐macroglobulin, a specific ligand for the low‐density lipoprotein receptor‐related protein‐1 (LRP1) and Angiopep‐2 can share the same receptor. In addition, LRP1 was detected in glioblastomas and brain metastases from lung and skin cancers. Fluorescent microscopy also revealed that Alexa488‐Angiopep‐2 co‐localized with LRP1 in brain endothelial cell monolayers. Overall, these results suggest that Angiopep‐2 transport across the BBB is, in part, mediated by LRP1.

The chemopreventive properties of chlorogenic acid reveal a potential new role for the microsomal glucose-6-phosphate translocase in brain tumor progression

BackgroundChlorogenic acid (CHL), the most potent functional inhibitor of the microsomal glucose-6-phosphate translocase (G6PT), is thought to possess cancer chemopreventive properties. It is not known, however, whether any G6PT functions are involved in tumorigenesis. We investigated the effects of CHL and the potential role of G6PT in regulating the invasive phenotype of brain tumor-derived glioma cells.ResultsRT-PCR was used to show that, among the adult and pediatric brain tumor-derived cells tested, U-87 glioma cells expressed the highest levels of G6PT mRNA. U-87 cells lacked the microsomal catalytic subunit glucose-6-phosphatase (G6Pase)-α but expressed G6Pase-β which, when coupled to G6PT, allows G6P hydrolysis into glucose to occur in non-glyconeogenic tissues such as brain. CHL inhibited U-87 cell migration and matrix metalloproteinase (MMP)-2 secretion, two prerequisites for tumor cell invasion. Moreover, CHL also inhibited cell migration induced by sphingosine-1-phosphate (S1P), a potent mitogen for glioblastoma multiform cells, as well as the rapid, S1P-induced extracellular signal-regulated protein kinase phosphorylation potentially mediated through intracellular calcium mobilization, suggesting that G6PT may also perform crucial functions in regulating intracellular signalling. Overexpression of the recombinant G6PT protein induced U-87 glioma cell migration that was, in turn, antagonized by CHL. MMP-2 secretion was also inhibited by the adenosine triphosphate (ATP)-depleting agents 2-deoxyglucose and 5-thioglucose, a mechanism that may inhibit ATP-mediated calcium sequestration by G6PT.ConclusionWe illustrate a new G6PT function in glioma cells that could regulate the intracellular signalling and invasive phenotype of brain tumor cells, and that can be targeted by the anticancer properties of CHL.

New Angiopep-Modified Doxorubicin (ANG1007) and Etoposide (ANG1009) Chemotherapeutics With Increased Brain Penetration

This report describes the synthesis and preliminary biological characterization of 2 (ANG1007) and 3 (ANG1009), two new chemical entities under development for the treatment of primary and secondary brain cancers. 2 consists of three doxorubicin molecules conjugated to Angiopep-2, a 19-mer peptide that crosses the blood-brain barrier (BBB) by an LRP-1 receptor-mediated transcytosis mechanism. 3 has a similar structure, with the exception that three etoposide moieties are conjugated to Angiopep-2. Both agents killed cancer cell lines in vitro with similar IC(50) values and with apparently similar cytotoxic mechanisms as unconjugated doxorubicin and etoposide. 2 and 3 exhibited dramatically higher BBB influx rate constants than unconjugated doxorubicin and etoposide and pooled within brain parenchymal tissue. Passage through the BBB was similar in Mdr1a (-/-) and wild type mice. These results provide further evidence of the potential of this drug development platform in the isolation of novel therapeutics with increased brain penetration.

Transport characteristics of a novel peptide platform for CNS therapeutics

New and effective therapeutics that cross the blood‐brain barrier (BBB) are critically needed for treatment of many brain diseases. We characterize here a novel drug development platform that is broadly applicable for the development of new therapeutics with increased brain penetration. The platform is based on the Angiopep‐2 peptide, a sequence derived from ligands that bind to low‐density lipoprotein receptor‐related protein‐1 (LRP‐1), a receptor expressed on the BBB. Fluorescent imaging studies of a Cy5.5Angiopep‐2 conjugate and immunohistochemical studies of injected Angiopep‐2 in mice demonstrated efficient transport across the BBB into brain parenchyma and subsequent co‐localization with the neuronal nuclei‐selective marker NeuN and the glial marker glial fibrillary acidic protein (GFAP). Uptake of [125I]‐Angiopep‐2 into brain endothelial cells occurred by a saturable mechanism involving LRP‐1. The primary sequence and charge of Angiopep‐2 were crucial for its passage across the BBB. Overall, the results demonstrate the significant potential of this platform for the development of novel neurotherapeutics.

ANG4043, a Novel Brain-Penetrant Peptide–mAb Conjugate, Is Efficacious against HER2-Positive Intracranial Tumors in Mice

Anti-HER2 monoclonal antibodies (mAb) have been shown to reduce tumor size and increase survival in patients with breast cancer, but they are ineffective against brain metastases due to poor brain penetration. In previous studies, we identified a peptide, known as Angiopep-2 (An2), which crosses the blood–brain barrier (BBB) efficiently via receptor-mediated transcytosis, and, when conjugated, endows small molecules and peptides with this property. Extending this strategy to higher molecular weight biologics, we now demonstrate that a conjugate between An2 and an anti-HER2 mAb results in a new chemical entity, ANG4043, which retains in vitro binding affinity for the HER2 receptor and antiproliferative potency against HER2-positive BT-474 breast ductal carcinoma cells. Unlike the native mAb, ANG4043 binds LRP1 clusters and is taken up by LRP1-expressing cells. Measuring brain exposure after intracarotid delivery, we demonstrate that the new An2–mAb conjugate penetrates the BBB with a rate of brain entry (Kin) of 1.6 × 10−3 mL/g/s. Finally, in mice with intracranially implanted BT-474 xenografts, systemically administered ANG4043 increases survival. Overall, this study demonstrates that the incorporation of An2 to the anti-HER2 mAb confers properties of increased uptake in brain endothelial cells as well as BBB permeability. These characteristics of ANG4043 result in higher exposure levels in BT-474 brain tumors and prolonged survival following systemic treatment. Moreover, the data further validate the An2–drug conjugation strategy as a way to create brain-penetrant biologics for neuro-oncology and other CNS indications. Mol Cancer Ther; 14(1); 129–40. ©2014 AACR.

MT1-MMP down-regulates the glucose 6-phosphate transporter expression in marrow stromal cells : a molecular link between pro-MMP-2 activation, chemotaxis, and cell survival.

Bone marrow-derived stromal cells (BMSC) are avidly recruited by experimental vascularizing tumors, which implies that they must respond to tumor-derived growth factor cues. In fact, BMSC chemotaxis and cell survival are regulated, in part, by the membrane type-1 matrix metalloproteinase (MT1-MMP), an MMP also involved in pro-MMP-2 activation and in degradation of the extracellular matrix (ECM). Given that impaired chemotaxis was recently observed in bone marrow cells isolated from a glucose 6-phosphate transporter-deficient (G6PT-/-) mouse model, we sought to investigate the potential MT1-MMP/G6PT signaling axis in BMSC. We show that MT1-MMP-mediated activation of pro-MMP-2 by concanavalin A (ConA) correlated with an increase in the sub-G1 cell cycle phase as well as with cell necrosis, indicative of a decrease in BMSC survival. BMSC isolated from Egr-1-/- mouse or MT1-MMP gene silencing in BMSC with small interfering RNA (siMT1-MMP) antagonized both the ConA-mediated activation of pro-MMP-2 and the induction of cell necrosis. Overexpression of recombinant full-length MT1-MMP triggered necrosis and this was signaled through the cytoplasmic domain of MT1-MMP. ConA inhibited both the gene and protein expression of G6PT, while overexpression of recombinant G6PT inhibited MT1-MMP-mediated pro-MMP-2 activation but could not rescue BMSC from ConA-induced cell necrosis. Cell chemotaxis in response to the tumorigenic growth factor sphingosine 1-phosphate was significantly abrogated in siMT1-MMP BMSC and in chlorogenic acid-treated BMSC. Altogether, we provide evidence for an MT1-MMP/G6PT signaling axis that regulates BMSC survival, ECM degradation, and mobilization. This may lead to optimized clinical applications that use BMSC as a platform for the systemic delivery of therapeutic or anti-cancer recombinant proteins in vivo.

A PSP94-derived peptide PCK3145 inhibits MMP-9 secretion and triggers CD44 cell surface shedding: Implication in tumor metastasis

Purpose: PCK3145 is a synthetic peptide corresponding to amino acids 31–45 of prostate secretory protein 94, which can reduce experimental skeletal metastases and prostate tumor growth in vivo. Part of its biological action involves the reduction of circulating plasma matrix metalloproteinase (MMP)-9, a crucial mediator in extracellular matrix (ECM) degradation during tumor metastasis and cancer cell invasion. The antimetastatic mechanism of action of PCK3145 is however, not understood. Experimental design: HT-1080 fibrosarcoma cells were treated with PCK3145, and cell lysates used for immunoblot analysis of small GTPase RhoA and membrane type (MT)1-MMP protein expression. Conditioned media was used to monitor soluble MMP-9 gelatinolytic activity by zymography and protein expression by immunoblotting. RT-PCR was used to assess RhoA, MT1-MMP, MMP-9, RECK, and CD44 gene expression. Flow cytometry was used to monitor cell surface expression of CD44 and of membrane-bound MMP-9. Cell adhesion was performed on different purified ECM proteins, while cell migration was specifically performed on hyaluronic acid (HA). Results: We found that PCK3145 inhibited HT-1080 cell adhesion onto HA, laminin-1, and type-I collagen suggesting the common implication of the cell surface receptor CD44. In fact, PCK3145 triggered the shedding of CD44 from the cell surface into the conditioned media. PCK3145 also inhibited MMP-9 secretion and binding to the cell surface. This effect was correlated to increased RhoA and MT1-MMP gene and protein expression. Conclusions: Our data suggest that PCK3145 may antagonize tumor cell metastatic processes by inhibiting both MMP-9 secretion and its potential binding to its cell surface docking receptor CD44. Such mechanism may involve RhoA signaling and increase in MT1-MMP-mediated CD44 shedding. Together with its beneficial effects in clinical trials, this is the first demonstration of PCK3145 acting as a MMP secretion inhibitor.

Abstract 2465: Targeting HER2-positive brain metastases by incorporating the brain-penetrant Angiopep-2 peptide to an anti-HER2 antibody and anti-HER2 antibody drug conjugate

Monoclonal antibodies directed against receptor tyrosine kinases such as HER2 have been demonstrated to reduce tumor size and increase survival. However, these agents achieve little to no brain penetration, making them ineffective against metastatic brain tumors. The blood-brain barrier (BBB), efficient at restricting entry of proteins such as mAbs and anticancer drugs into the brain, is comprised of capillary endothelial cells with tight junctions and efflux pumps. We have created a family of peptides (Angiopeps) which use receptor-mediated transcytosis to enter the brain. Conjugation of the Angiopep-2 (An2) to confer brain permeability has been validated for small molecules (ANG 1005, Phase II), peptides and proteins. The brain-penetrant An2 has also been incorporated to a humanized anti-HER2 mAb. This Angiopep-Antibody Conjugate, ANG4043, displays HER2 binding affinity and in vitro cytotoxic potency similar to that of native anti-HER2. ANG4043 demonstrates a high rate of entry into the brain. ANG4043 reduces the tumor size of BT-474 human breast cancer cells when implanted in the brain, consistent with achieving therapeutic concentrations. Here we describe chemical conjugation between three molecules: the An2, a cytotoxic drug (docetaxel or maytansine), and a mAb directed against HER2. These new An2-antibody-drug-conjugates (An2-ADCs) show a higher in vitro anti-proliferative potency than unconjugated mAb against HER2+ BT-474 and HC-19554 cells that are sensitive and resistant to Herceptin, respectively. Furthermore, they demonstrate a high rate of entry into the brain when compared to controls, leading to a reduction in brain tumor size and to an increase in the survival of mice bearing intracranial BT-474 tumors. Furthermore, An2-anti-HER2 derivatives are also efficacious in peripheral tissues since they inhibited the growth of subcutaneous BT-474 luciferase tumors. Overall, these data demonstrate that the conjugation of an Angiopep to therapeutic mAbs or ADCs can increase their efficacy in the CNS without affecting their anticancer properties outside of the brain. These results extend the validation of Angiopep conjugation beyond small anticancer drugs to include larger molecules such as therapeutic mAbs and ADCs for development of new brain-penetrant therapeutics for brain malignancies. Citation Format: Michel Demeule, Sanjoy Das, Christian Che, Gaoqiang Yang, Jean-Christophe Currie, Simon Lord-Dufour, Sasmita Tripathy, Anthony Regina, Jean-Paul Castaigne, Jean E. Lachowicz. Targeting HER2-positive brain metastases by incorporating the brain-penetrant Angiopep-2 peptide to an anti-HER2 antibody and anti-HER2 antibody drug conjugate. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2465. doi:10.1158/1538-7445.AM2015-2465

Abstract 2657: Utilization of the Angiopep platform to enable brain penetration of therapeutic mAbs or Antibody-Drug Conjugates for treatment of brain tumors

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Monoclonal antibodies directed against receptor tyrosine kinases such as HER2 have been demonstrated to reduce tumor size and increase survival. However, these agents achieve little to no brain penetration, making them ineffective against metastatic brain tumors. The blood-brain barrier (BBB), efficient at restricting entry of proteins such as mAbs into the brain, is comprised of capillary endothelial cells with tight junctions and efflux pumps. Entry of nutrients, hormones, and other required molecules is accomplished by processes such as receptor-mediated transcytosis. As low-density lipoprotein receptor-related protein 1 (LRP1) is known to perform this function in BBB endothelial cells, we have created a family of peptides (Angiopeps) designed for LRP1 recognition. Conjugation of the Angiopep-2 (An2) to confer brain permeability has been validated for small molecules (ANG 1005, Phase II), peptides and proteins. For example, therapeutic concentrations of an anti-HER2 mAb have been achieved with An2 conjugation. This Angiopep-Antibody Conjugate, ANG4043, displays HER2 binding affinity and in vitro cytotoxic potency similar to that of native anti-HER2. ANG4043 demonstrates a high rate of entry into the brain, consistent with achieving therapeutic concentrations. Mice intracranially implanted with BT-474 human breast cancer cells showed reduced brain tumor size when dosed with ANG4043 compared to controls and increased mice survival. Here, we also describe the chemical conjugation between a brain penetrant Angiopep, a cytotoxic agent and a mAb directed against HER2. This new peptide-antibody-drug-conjugate shows a much higher in vitro anti-proliferative potency against HER2+ BT-474 cells than the native antibody. Furthermore, this new peptide-drug-antibody-conjugate demonstrates a high rate of entry into the brain when compared to the unconjugated antibody. Overall, these data demonstrate that the addition of an Angiopep to therapeutic mAbs or Antibody Drug Conjugates (ADCs) can improve their brain penetration. These results extend the validation of Angiopep conjugation beyond small molecules and peptides to include larger molecules such as therapeutic mAbs or ADCs for development of new brain-penetrant antitumor therapeutics. Citation Format: Michel Demeule, Jean E. Lachowicz, Sasmita Tripathy, Giogang Yang, Sanjoy Das, Christian Che, Jean-Christophe Currie, Simon Lord-Dufour, Anthony Regina, Jean-Paul Castaigne. Utilization of the Angiopep platform to enable brain penetration of therapeutic mAbs or Antibody-Drug Conjugates for treatment of brain tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2657. doi:10.1158/1538-7445.AM2014-2657

Abstract 864: ANG4043: A new brain-penetrant peptide-antibody conjugate that reduces tumor growth in a HER2-positive orthotopic tumor model.

While monoclonal antibodies to receptor tyrosine kinases such as HER2 have been demonstrated to reduce tumor size and increase survival, these agents achieve little to no brain penetration, making them ineffective against metastatic brain tumors. The blood-brain barrier (BBB), which restricts entry of proteins such as mAbs into the brain, is comprised of capillary endothelial cells with tight junctions and efflux pumps. Brain entry of nutrients, hormones, and other required molecules is accomplished by processes such as receptor-mediated transcytosis. As low-density lipoprotein receptor-related protein 1 (LRP1) is known to perform this function in BBB endothelial cells, we have created a family of peptides (Angiopeps) designed for LRP1 recognition. These proprietary Angiopeps can be used to create novel Peptide-Drug Conjugates that successfully cross the BBB by LRP1-mediated transcytosis. Here we describe chemical conjugation of Angiopep-2 (An2) to a mAb against HER2. This Peptide-Antibody Conjugate, ANG 4043, displays HER2 binding affinity and in vitro cytotoxic potency similar to that of native anti-HER2. ANG4043 demonstrates a high rate of entry into the brain, consistent with achieving therapeutic concentrations. The plasma half-life of ANG4043 is similar to that of Anti-HER2 in mouse. Mice with intracranially implanted BT-474 cells showed reduced brain tumor size when dosed with ANG4043 compared to controls. Overall, these data demonstrate that a brain-penetrant Peptide-Antibody Conjugate is efficacious in a mouse HER2-positive tumor model. These results extend the validation of An2 conjugation beyond small molecules and peptides to include larger molecules such as therapeutic mAbs for development of new brain-penetrant antitumor therapeutics. Citation Format: Jean E. Lachowicz, Michel Demeule, Christian Che, Sasmita Tripathy, Jean-Christophe Currie, Anthony Regina, Tran Nguyen, Simon Lord-Dufour, Jean-Paul Castaigne. ANG4043: A new brain-penetrant peptide-antibody conjugate that reduces tumor growth in a HER2-positive orthotopic tumor model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 864. doi:10.1158/1538-7445.AM2013-864