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Tumor progression is intimately associated with the vasculature, as tumor proliferation induces angiogenesis and tumor cells metastasize to distant organs via blood vessels. However, whether tumor invasion is associated with blood vessels remains unknown. As glioblastoma (GBM) is featured by aggressive invasion and vascular abnormalities, we characterized the onset of vascular remodeling in the diffusive tumor-infiltrating zone by establishing new spontaneous GBM models with robust invasion capacity. Normal brain vessels underwent a gradual transition to severely impaired tumor vessels at the GBM periphery over several days. Increasing vasodilation from the tumor periphery to tumor core was also found in human GBM. The levels of VEGF and VEGFR2 showed a spatial correlation with the extent of vascular abnormality spanning the tumor invading zone. Blockade of VEGFR2 suppressed vascular remodeling at the tumor periphery, confirming the role of VEGF-VEGFR2 signaling in invasion-associated vascular transition. As ANGPT2 was expressed only in a portion of the central tumor vessels, we developed a ligand-independent Tie2-activating antibody that can phosphorylate Tie2 in vivo. This agonistic Tie2 antibody effectively normalized the vasculature in both the tumor periphery and tumor center, similar to VEGFR2 blockade. Mechanistically, this antibody-based Tie2 activation induced VE-PTP-mediated VEGFR2 dephosphorylation in vivo. Thus, our study reveals that the normal-to-tumor vascular transition spatio-temporally associates with GBM invasion and may be controlled by Tie2 activation with a novel mechanism-of-action.

Background: Metastatic TNBC (mTNBC) has a poor prognosis. Preclinical data suggests benefit for combination therapy of immune checkpoint inhibitor and anti-angiogenesis. Olinvacimab (O) is a fully humanised monoclonal antibody (MAB) which binds to Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) and antiangiogenic and antitumor effects have been demonstrated. Pembrolizumab (P) is an anti-PD1 MAB. This study aimed to identify the safety and tolerability of O and P to establish a phase 2 recommended dose of O. Methods: From December 2018 to September 2020, we conducted a two-site, single arm, open-label study of O and P in pts with mTNBC. Eligible patients (pts) were >18 years, had ER, PR & HER2-negative MBC with at least one measurable lesion and adequate organ function. Pts with history of serious thromboembolism, gastrointestinal haemorrhage and prior anti-VEGF therapy were excluded. A modified Toxicity Probability Interval design was used. Pts received O 12 mg/kg q7d (dose level 1) or 16mg/kg day q7d (dose level 2) in combination with P 200mg flat dose day 1 q21d. Treatment continued until dose limiting toxicity (DLT), disease progression (PD) or treatment intolerance. Results: 11 pts, median age 62 (range 39-67) were recruited and received at least one dose of treatment. 8 (73%) had ECOG PS 1 and 3 (27%) had ECOG PS 2. 5 pts had previous chemotherapy for mTNBC (with 3 pts also having received immunotherapy), 6 pts were treated in the first-line metastatic setting (with all pts having received anthracycline and taxane in the adjuvant setting). 5 pts received O at 12mg/kg with P, completing a median of 6 cycles (range 1-18). As no DLTs were seen, 6 pts were treated with O at 16mg/kg with median of 8 cycles (range 2-21), with no DLTs being observed. Treatment was ceased due to PD in 6 pts, 3 pts are receiving treatment at data cut-off. Haemangiomas were seen in 8 pts accounting for 47 events of CTCAE grade 1 and 21 events of grade 2. Treatment emergent adverse events (TEAEs) of ≥grade 3 was seen in 6 pts (27 events), with 8 events being related to treatment. 4 pts (36%) had partial response (PR) as best overall response 5 pts (45%) had clinical benefit (PR+SD≥24weeks). Conclusions: Combination therapy of O and P was well tolerated with evidence of efficacy in mTNBC pts who had all previously received anthracycline and taxanes, with 3 pts having previously received immunotherapy. These results support the combination entering into a phase 2 study. Citation Format: Arlene Chan, Eugene Moylan, Sally Jackson, Jeannette Devoto, Nicola Jones, Silvie Radmil, Kate Wilkinson, Aflah Roohullah, Tamiem Adam, Seon Young Lee, Weon Sup Lee, Jin-San Yoo. Phase Ib trial of olinvacimab and pembrolizumab in patients with metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS10-18.

Monoclonal antibody (mAb) drugs are clinically important for the treatment of various diseases. TTAC-0001 is under development as a new anti-cancer antibody drug targeting VEGFR-2. As the less severe toxicity of TTAC-0001 compared to Bevacizumab, likely due to the decreased in vivo half-life, seems to be related to its structural flexibility, it is important to map the exact flexible regions. Although the 13C/15N-labeled protein is required for NMR analyses, it is difficult to obtain antibody fragments (Fab and scFv) containing disulfide bonds through general cytosolic expression in Escherichia coli (E. coli). Here, we notably increased the periplasmic expression of the 13C/15N-labeled TTAC-0001-Fab (13C/15N-TTAC-Fab) through simple isopropyl β-D-1-thiogalactopyranoside (IPTG)-induction at an increased optical density (1.5 OD600nm). Through NMR triple resonance experiments, two loop insertions (LI-1 between the VH and CH1; LI-2 between the VL and CL) were confirmed to be highly flexible. The additional LIs could be another way to engineer the antibody by changing the pharmacokinetic properties.

The VEGF pathway remains an important target in GBM given its vascularity and autocrine VEGF signalling. Olinvacimab (TTAC-0001) is a fully humanised VEGFR2 Mab that binds and inhibits the receptor. This report assesses the safety, dosing schedules and efficacy of Olinvacimab in recurrent GBM. We conducted a two-site, 3 arm, open-label study of Olinvacimab in recurrent GBM. Eligible patients were ≥18 years with RANO-measurable lesion, KPS ≥ 80, and had completed chemoradiotherapy without prior bevacizumab therapy. We assessed three arms, 8 mg/kg and 12mg/kg weekly for 3 of every 4 weeks, and 12 mg/kg weekly. Three patients were treated in arms 1 and 2 and 6 in arm 3. Safety assessments were performed prior to dose escalation. The main toxicity was development of grade 1 (67%) and 2 (8%%) cutaneous haemangiomas. Common toxicities seen with other VEGF directed therapies, including hypertension, impaired wound healing, and proteinuria were not seen in this cohort. Efficacy was assessed by MRI using RANO criteria. 6 month PFS was 17%, with disease control in 25%, with steroid dose reduction. The longest response was 15 months. On DCE MRI, there was no significant difference in perfusion parameters between baseline and 1st follow-up MRI comparing those with SD and PD. However, 6 of 12 patients showed decreased Ktrans > 20 % of baseline, consistent with an anti-angiogenic effect of Olinvacimab. Pharmacokinetics showed a decreased clearance rate and increased half-life of Olinvacimab compared to the prior Phase I study. Pharmacodynamic studies showed significantly higher levels of angiogenic markers, particularly VEGF-A in those treated at 12mg/kg vs arm 1. VEGF-A, C and D levels were elevated in patients with SD compared to those with PD. Conclusion: Olinvacimab was well tolerated with a different toxicity profile to other VEGFR directed therapies. There were promising responses in 25% of patients.

Monoclonal antibody (mAb) drugs are clinically important for the treatment of various diseases. TTAC-0001 is under development as a new anti-cancer antibody drug targeting VEGFR-2. As the less severe toxicity of TTAC-0001 compared to Bevacizumab, likely due to the decreased in vivo half-life, seems to be related to its structural flexibility, it is important to map the exact flexible regions. Although the

TME (tumor microenvironment) consists of blood & lymphatic vessels, stromal cells, and immune cells such as lymphocytes, macrophages, and antigen-presenting cells (APC). Cellular interactions among various immune cell types within TME regulate tumor growth, metastasis, and resistance to cancer therapy. V-domain Ig suppressor of T cell activation (VISTA) is a negative checkpoint regulator highly expressed on tumor-infiltrating myeloid-derived suppressor cells (MDSC) and tumor-associated macrophages (TAMs) and VISTA blockade could enhance antitumor immunity in TME. PMC-309 binding to VISTA expressing cells is highly selective and the selectivity is maintained even in the low pH conditions that mimic TME. Binding of PMC-309 on MDSC cells enhances the secretion of IFN-γ, TNF-α, and IL-2 in Mixed Lymphocyte Reaction (MLR) settings. In in vivo study, PMC-309 suppressed tumor growth, which was further attenuated with an anti-PD1 antibody. The anti-tumor activity was associated with enhanced T cell activation, increased secretion of pro-inflammatory cytokines, and increased penetration of tumor-infiltrating leukocytes (TIL) into TME. Patients who became resistant to anti-CTLA-4 and anti-PD(L)1 antibody showed increased expression of VISTA, suggesting that anti-VISTA therapeutics can help to treat the patients who do not respond well to other immuno-oncology drugs. We are developing PMC-309 as a next generation immuno-oncology (IO) agent, which can convert immunologically cold into hot tumors as a mono- or combo- therapy with other IO agent. Citation Format: Cheon Ho Park, Sang Soon Byun, Jin Yong An, Sun Hyung Ha, Hye Rim Han, Nu Ri Kang, Beom Yong Park, Eun Ah Lee, Hyun Sun Park, Jin-San Yoo, Weon Sup Lee. PMC309, a highly selective anti-VISTA antibody enhances T cell activation through blocking the interaction of T cells and myeloid derived suppressor cells (MDSC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1626.

e14545 Background: Recurrent GBM is difficult to treat. Single agent checkpoint blockade has not improved outcomes. Angiogenesis is a rational drug target for rGBM and targeting angiogenesis may benefit pseudoprogression and cerebral oedema. O is a fully human monoclonal antibody (MAB) which binds to Vascular Endothelial Growth Factor Receptor 2 (VEGFR2) with antiangiogenic and antitumour effects. P is an anti-PD1 MAB. This study aimed to identify the safety and tolerability of O combined with P and to establish a recommended phase 2 combination dose. Methods: From January to October 2019, we conducted a two-site, single arm, open-label study of O with P in patients with rGBM. Eligible patients (pts) were ≥18 years with at least one RANO-measurable lesion, KPS≥80, and had completed standard chemoradiotherapy and had no contraindications to O or P. No prior bevacizumab was allowed. A modified Toxicity Probability Interval design was used. Pts received O 12 mg/kg day 1/8/15 q21d (dose level 1) or O 16mg/kg day 1/8/15 q21d (dose level 2) in combination with P 200mg flat dose day 1 q21d. Pts were reviewed weekly and underwent DCE-MRI at baseline and 6-weekly. Treatment continued to progression, toxicity or withdrawal. Results: 9 pts, median age 53 (range 34-67) were recruited and received at least one study treatment. Median time since diagnosis was 15.6 months. 7 (78%) had KPS 90 and 2 (22%) KPS 80. 3 pts received O 12mg/kg with P, completing a median 3 cycles (range 2-6). As no Dose Limiting Toxicities (DLTs) were seen, 3 pts were treated with O 16mg/kg with expansion total 6 when no DLTs were observed. At 16mg/kg, a median of 2 treatment cycles was received (range 2-6). Treatment was ceased due to progressive disease (PD) in 8 pts with one ongoing at data cutoff. No DLTs were observed in any pts. Three grade 3 treatment emergent adverse events (TEAEs) were noted (blurred vision, fatigue, and seizure). Hemangioma is a known toxicity of O and was seen in 6 pts, with 11 grade 1 and 1 grade 2 event. 4 pts (44%) had stable disease (SD) and 5 pts (56%) had PD as best response. Conclusions: The combination of O with P was safe and tolerable at the full single agent dose of each drug. No DLTs were observed. The combination did not show efficacy in this setting. Clinical trial information: NCT03722342.

Weon Sup Lee,1 Sang Ryeol Shim,1 Seon Young Lee,1 Jin San Yoo,1 Sung Kweon Cho2 1PharmAbcine, Inc., Daejeon, Republic of Korea; 2Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, Republic of Korea Background: VEGF is a highly selective mitogen that serves as the central regulator of tumor angiogenesis by mediating endothelial proliferation, permeability, and survival. Tanibirumab (TTAC-0001) is a fully human IgG1 monoclonal antibody derived from a fully human naïve single-chain variable fragment (ScFv) phage library that was developed to inhibit the effects of VEGF in the treatment of solid tumors, especially those of the brain. Methods: In the present study, we conducted intravenous pharmacokinetic studies of TTAC-0001 in mice, rats, and cynomolgus monkeys. At the doses studied (3 mg/kg, 10 mg/kg, 30 mg/kg), TTAC-0001 exhibited dose proportionality in mice and monkeys. At a dose of ~10 mg/kg, the clearance of TTAC-0001 from serum was 0.017 mL/h in mice, 0.35 mL/h in rats, and 2.19 mL/h in cynomolgus monkeys, and the terminal half-life ranged from 20–30 h among the three species. Pharmacokinetic data in mice, rats, and cynomolgus monkeys were used to predict the pharmacokinetics of TTAC-0001 in humans using allometric scaling. The predicted serum clearance of TTAC-0001 in humans was 102.45 mL/h and the terminal half-life was 27.52 h. Results: The maximum life span-corrected clearance value was 72.92 mL/h. The observed clearance in humans was more similar to the predicted scaled clearance. Conclusion: We investigated the pharmacokinetics of TTAC-0001 in mice, rats, and cynomolgus monkeys after intravenous administration. At the doses studied, TTAC-0001 exhibited dose proportionality in mice and monkeys. The scaled pharmacokinetics of TTAC-0001 reported here was useful for designing first-in-human studies. Allometric scaling in the therapeutic antibody is feasible. Keywords: VEGF2, tanibirumab, pharmacokinetics, allometry, clearance, biodistribution

Vascular endothelial growth factor (VEGF) and its receptors are considered the primary cause of tumor-induced angiogenesis. Specifically, VEGFR-2/kinase insert domain receptor (KDR) is part of the major signaling pathway that plays a significant role in tumor angiogenesis, which is associated with the development of various types of tumor and metastasis. In particular, KDR is involved in tumor angiogenesis as well as cancer cell growth and survival. In this study, we evaluated the therapeutic potential of TTAC-0001, a fully human antibody against VEGFR-2/KDR. To assess the efficacy of the antibody and pharmacokinetic (PK) relationship in vivo, we tested the potency of TTAC-0001 in glioblastoma and colorectal cancer xenograft models. Antitumor activity of TTAC-0001 in preclinical models correlated with tumor growth arrest, induction of tumor cell apoptosis, and inhibition of angiogenesis. We also evaluated the combination effect of TTAC-0001 with a chemotherapeutic agent in xenograft models. We were able to determine the relationship between PK and the efficacy of TTAC-0001 through in vivo single-dose PK study. Taken together, our data suggest that targeting VEGFR-2 with TTAC-0001 could be a promising approach for cancer treatment.

Purpose Targeting of vascular endothelial growth factor receptors (VEGFRs) has potential anti-angiogenic effects because VEGFR-2 is the major signaling regulator of VEGF/VEGFR pathways. We aimed to elucidate the drug mechanism and anti-tumor efficacy of TTAC-0001, a novel, fully human anti-VEGFR-2/KDR monoclonal antibody, in mouse orthotopic breast cancer model using multi-modal bioimaging. Materials and methods We used orthotopic xenograft tumor model in which human breast cancer cells (MDA-MB-231) were injected into the right mammary fat pad of Balb/c nude mice. We investigated its biodistribution using serial fluorescence imaging after injecting fluorescent-labelled-drug and mode of action using Matrigel plug angiogenesis assays. The anti-tumor efficacy of drug was assessed using ultrasonography and bioluminescence imaging. Histopathologic analyses, including hematoxylin and eosin staining and immunohistochemistry with anti-CD31 and anti-Ki-67 antibodies, were performed. Each experiment had four groups: control, bevacizumab 10 mg/kg (BVZ-10 group), TTAC-0001 2 mg/kg (TTAC-2 group), and TTAC-0001 10 mg/kg (TTAC-10 group). Results The TTAC-10 group showed good tumor targeting that lasted for at least 6 days and had a good anti-angiogenic effect with decreased hemoglobin content and fewer CD31-positive cells in the Matrigel plug. Compared with BVZ-10 and TTAC-2 groups, the TTAC-10 group showed the strongest anti-tumor efficacy, inhibiting tumor growth as detected by ultrasonography and bioluminescence imaging. The TTAC-10 group also showed the lowest viable tumor and micro-vessel areas and the lowest Ki-67 index in histopathologic analyses. Conclusion We firstly demonstrated that TTAC-0001 effectively inhibited tumor growth and neovascularization in mouse orthotopic breast cancer model. It may provide a future treatment option for breast cancer.

SummaryBackground Tanibirumab is a fully human monoclonal antibody to vascular endothelial growth factor receptor 2 (VEGFR-2). We conducted a first-in-human phase I study of tanibirumab in patients with solid tumors refractory to standard chemotherapy. Primary endpoints were evaluating safety, pharmacokinetics (PKs), estimating maximum-tolerated dose (MTD) and recommended phase II dose (RP2D). Methods We designed our study to escalate tanibirumab at 9 different dose levels with a 3 + 3 method and tanibirumab (1–28 mg/kg) was administered intravenously on D1, 8, 15 in 28-day courses. Dose limiting toxicities (DLTs) were only assessed during the first cycle of treatment and response evaluation was performed every 2 cycles. The effects of tanibirumab on several angiogenic factors were analyzed. Results From October 2011 to September 2013, a total of 26 patients with refractory solid tumors were enrolled. The median age was 58 years (range, 27–75) and 20 patients were male. The most common tumor type was colorectal cancer (N = 19) and seven patients had a history of previous bevacizumab treatment. As hemangioma continued to occur, the final dose level, 28 mg/kg, was not performed. DLTs were not found, and the MTD was confirmed to be 24 mg/kg. Hemangioma was observed in 16 patients (61.5%), but all were grade 1–2 and disappeared after discontinuation of the study drug. Among the 18 patients in the efficacy set, no objective response was observed, but 11 patients showed stable disease. PKs were characterized by dose-dependent linear exposure and the mean trough concentrations exceeded biologically relevant target levels at 12 mg/kg and above. Serum VEGF, soluble VEGFR-2, and PlGF increased at the 4 mg/kg dose level and above. Conclusions Treatment with tanibirumab showed a tolerable toxicity profile and modest clinical efficacy in patients with refractory solid tumors. A phase II trial of tanibirumab is ongoing now.

Chlorpheniramine is an anti-histamine agent on IgE-mediated inflammation. In order to investigate the immunomodulatory effects of chlorpheniramine, we assessed the changes of peripheral mononuclear cell populations and other general clinical parameters, including hematology and clinical chemistry, following chlorpheniramine administration in rats. Since prednisolone is commonly co-prescribed with anti-histamine in many hypersensitive reactions, we also examined the changes to compare the results after the prednisolone administration. Chlorpheniramine (50, 100 and 200 μg/kg) and prednisolone (1, 2 and 4 mg/kg) were intramuscularly administered to female Sprague-Dawley (SD) rats 3 times, at intervals of 1 week. Except the clinical signs, such as stiffness and abnormal gait due to the local toxicity at injection sites, no other significant changes in body weights, urinalysis, and macroscopic examination were noted in the animals given chlorpheniramine. On the other hand, white blood cells, especially B cells and monocytes, showed a dose-dependent increase in the chlorpheniramine-treated animals; whereas, the numbers of both B and T cells (helper T and cytotoxic T, NKT cells) were decreased in the prednisolone-treated animals. Taken together, these results suggest that chloropheniramine administration enhances white blood cells in the peripheral blood, mostly due to increases of the B cells and monocytes, but no T cells and NK cells.

BACKGROUD: The authors investigated whether expression of c-Met protein in glioblastomas is associated with overall survival and biologic features representing tumor invasiveness in patients with glioblastomas. METHODS: Paraffin-embedded specimens of glioblastomas from 62 patients treated in a single institution were assessed by immunohistochemical (IHC) analysis of c-Met expression. On the basis of the clinical data for these patients, the association between c-Met expression and clinicobiologic features representing tumor invasiveness was analyzed. RESULTS: c-Met overexpression was detected in 29.0% (18 of 62) of glioblastomas. In patients with c-Met overexpression, the median survival was 11.7 months (95% confidence interval [95% CI], 9.9 months-13.5 months), compared with a median survival of 14.3 months (95% CI, 7.6 months-21.0 months) for patients whose tumors had no or little expression of c-Met (P = .031). On the radiographic analysis, 9 of 18 patients (50%) with tumors overexpressing c-Met demonstrated invasive and multifocal lesions on the initial magnetic resonance images, whereas only 9 of 44 patients (20.5%) with tumors that expressed no or little c-Met demonstrated these features (P = .030). Using immunohistochemistry, we also found a significant association between c-Met expression and matrix metalloproteinase-2,-9 (P = .020 and P = .013). Furthermore, Myc overexpression was found to be closely correlated with c-Met overexpression on IHC analysis (P = .004). CONCLUSIONS: The authors suggest that c-Met overexpression is associated with shorter survival time and poor treatment response in glioblastomas, the mechanism for which is elevated tumor invasiveness on the molecular and clinical phenotypes. This implies that more effective therapeutic strategies targeting c-Met receptors may have important clinical implication. Cancer 2009. © 2008 American Cancer Society.

Angiogenesis is one of the most important processes for cancer cell survival, tumor growth and metastasis. Vascular endothelial growth factor (VEGF) and its receptor, particularly VEGF receptor-2 (VEGFR-2, or kinase insert domain-containing receptor, KDR), play critical roles in tumor-associated angiogenesis. We developed TTAC-0001, a human monoclonal antibody against VEGFR-2/KDR from a fully human naive single-chain variable fragment phage library. TTAC-0001 was selected as a lead candidate based on its affinity, ligand binding inhibition and inhibition of VEGFR-2 signal in human umbilical vein endothelial cells (HUVEC). TTAC-0001 inhibited binding of VEGF-C and VEGF-D to VEGFR-2 in addition to VEGF-A. It binds on the N-terminal regions of domain 2 and domain 3 of VEGFR-2. It could inhibit the phosphorylation of VEGFR-2/KDR and ERK induced by VEGF in HUVEC. TTAC-0001 also inhibited VEGF-mediated endothelial cell proliferation, migration and tube formation in vitro, as well as ex vivo vessel sprouting from rat aortic rings and neovascularization in mouse matrigel model in vivo. Our data indicates that TTAC-0001 blocks the binding of VEGFs to VEGFR-2/KDR and inhibits VEGFR-induced signaling pathways and angiogenesis. Therefore, these data strongly support the further development of TTAC-0001 as an anti-cancer agent in the clinic.

Protein chips are a powerful emerging technology with extensive biomedical applications. However, the development of optimal, economical surface materials capable of maintaining the activity of embedded proteins is a challenge. Here, we introduce a new optimized, low-cost, sol-gel biomaterial for use in protein chips with femtogram-level sensitivity. A novel protein chip material with significantly improved physical properties and sensitivity was produced using unique screening and selection methods. Using this platform, the sensitive, specific detection of the interactions between an HIV antigen and its antibody and between a cyclin-kinase protein pair was observed. This study is the first to demonstrate the detection of protein-protein interactions on sol-gel microarrays and describes an important improvement in the physical properties of sol-gel-derived protein chip materials for biomedical research.

Cystic fibrosis (CF) is a childhood hereditary disease in which the most common mutant form of the CF transmembrane conductance regulator (CFTR) ΔF508 fails to exit the endoplasmic reticulum (ER). Export of wild-type CFTR from the ER requires the coat complex II (COPII) machinery, as it is sensitive to Sar1 mutants that disrupt normal coat assembly and disassembly. In contrast, COPII is not used to deliver CFTR to ER-associated degradation. We find that exit of wild-type CFTR from the ER is blocked by mutation of a consensus di-acidic ER exit motif present in the first nucleotide binding domain. Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24. We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in ΔF508-expressing patients.

The mechanism(s) of cystic fibrosis transmembrane conductance regulator (CFTR) trafficking from the endoplasmic reticulum (ER) through the Golgi apparatus, the step impaired in individuals afflicted with the prevalent CFTR-ΔF508 mutation leading to cystic fibrosis, is largely unknown. Recent morphological observations suggested that CFTR is largely absent from the Golgi in situ (Bannykh, S. I., Bannykh, G. I., Fish, K. N., Moyer, B. D., Riordan, J. R., and Balch, W. E. (2000)Traffic 1, 852–870), raising the possibility of a novel trafficking pathway through the early secretory pathway. We now report that export of CFTR from the ER is regulated by the conventional coat protein complex II (COPII) in all cell types tested. Remarkably, in a cell type-specific manner, processing of CFTR from the core-glycosylated (band B) ER form to the complex-glycosylated (band C) isoform followed a non-conventional pathway that was insensitive to dominant negative Arf1, Rab1a/Rab2 GTPases, or the SNApREceptor (SNARE) component syntaxin 5, all of which block the conventional trafficking pathway from the ER to the Golgi. Moreover, CFTR transport through the non-conventional pathway was potently blocked by overexpression of the late endosomal target-SNARE syntaxin 13, suggesting that recycling through a late Golgi/endosomal system was a prerequisite for CFTR maturation. We conclude that CFTR transport in the early secretory pathway can involve a novel pathway between the ER and late Golgi/endosomal compartments that may influence developmental expression of CFTR on the cell surface in polarized epithelial cells.

e13522 Background: Treatment of recurrent GBM remains a challenge. The VEGF signal transduction pathway is upregulated in GBM. We evaluated Tanibirumab, a mAb to VEGFR2, in an open-label, dose-escalation, 3-arm, Phase 2a clinical trial. Primary and secondary endpoints were determining safety and efficacy (6-month PFS, ORR, DCR and OS). Methods: Eligibility criteria included age ≥19 yrs at 1st or 2nd recurrence of GBM, measurable disease, KPS≥80, and no prior bevacizumab. Patients were enrolled in 3 arms: Arm 1 (8mg/kg d1,8,15/q28 days); Arm 2 (12mg/kg d1,8,15/q28 days) and Arm 3 (12mg/kg weekly). Response evaluation with MRI (RANO criteria) including DCE, was performed every 2 cycles. Results: 12 patients were enrolled over 10 months from 2 sites: 3 patients each in Arms 1 & 2; 6 in Arm 3. The median age was 50 years and 8 were male. 6 patients had second recurrence. At 1st infusion, 8 out of 12 were on baseline corticosteroids. 10 patients have progressed. No dose limiting toxicities (DLT) were observed. Cutaneous hemangiomas (CH) were frequent (83% of patients) and all G2 or less. No drug-related G3 or 4 AEs were observed. All SAEs were unrelated to the study drug apart from G2 bleeding haemangioma and G2 cerebral haemorrhage. Expected AEs with anti-angiogenic drugs (hypertension; impaired wound healing) were not observed. Among 12 patients allocated to Arm 1, 2 and 3, no objective radiological responses were observed. 3 patients demonstrated stable disease (SD); 2 patients had SD beyond 4 cycles and are still receiving treatment at weeks 45 (Arm 1) & 20 (3). This was correlated with the highest expression of VEGFR2 using immunohistochemistry on archival tumour and blood vessels. Only 2 patients needed to initiate or increase corticosteroids for control of tumor edema while on treatment. Current data are immature to determine time to event efficacy endpoints (PFS,OS). Conclusions: Tanibirumab can be safely administered to patients with recurrent GBM, with CH being common. SD was seen in 2 patients up to 10+ months, with some indication that VEGFR2 expression may be a response biomarker. Clinical trial information: NCT03033524.

Soluble N-ethylmaleimide-sensitive factor-attachment protein receptor (SNARE) proteins of the vesicle-associated membrane protein (VAMP) and syntaxin families play a central role in vesicular trafficking through the formation of complexes between proteins present on vesicle and target membranes. Formation of these complexes is proposed to mediate aspects of the specificity of vesicle trafficking and to promote fusion of the lipid bilayers. In order to further understand the molecular mechanisms that organize membrane compartments, we have characterized seven new mammalian proteins of the VAMP and syntaxin families. The proteins are broadly expressed; however, syntaxin 13 is enriched in brain and VAMP 8 in kidney. The seven novel SNAREs localize in distinct patterns overlapping with Golgi, endosomal, or lysosomal markers. Our studies support the hypothesis that evolutionary radiation of these two gene families gave rise to sets of proteins whose differential expression and combinatorial associations define and organize the membrane compartments of cells.

Higher failure rates have been observed for devices at or adjacent to areas that have been measured or inspected by in-line x-ray during front end of line process steps. The failures are thought to be related to SiO2/Si interface damage caused by x-ray radiation during routine in-line element, material, and process monitoring. This issue has been noted for highly advanced integrated semiconductor devices following device failure mode analysis of Si wafers, with and without x-ray in-line inspection. A multiwavelength room-temperature photoluminescence (RTPL) study was performed to identify the presence of such damage in x-ray irradiated wafers from various types of x-ray inspection steps during device fabrication processes. It was found that x-ray radiation as low as 16 keV induced damage at the SiO2/Si interface. The damage to the SiO2/Si interface was successfully observed by using multiwavelength RTPL wafer mapping.

The small GTPase rab5 has been shown to represent a key regulator in the endocytic pathway of mammalian cells. Using a PCR approach to identify rab5 homologs in Saccharomyces cerevisiae, two genes encoding proteins with 54 and 52% identity to rab5, YPT51 and YPT53 have been identified. Sequencing of the yeast chromosome XI has revealed a third rab5-like gene, YPT52, whose protein product exhibits a similar identity to rab5 and the other two YPT gene products. In addition to the high degree of identity/homology shared between rab5 and Ypt51p, Ypt52p, and Ypt53p, evidence for functional homology between the mammalian and yeast proteins is provided by phenotypic characterization of single, double, and triple deletion mutants. Endocytic delivery to the vacuole of two markers, lucifer yellow CH (LY) and alpha-factor, was inhibited in delta ypt51 mutants and aggravated in the double ypt51ypt52 and triple ypt51ypt52ypt53 mutants, suggesting a requirement for these small GTPases in endocytic membrane traffic. In addition to these defects, the here described ypt mutants displayed a number of other phenotypes reminiscent of some vacuolar protein sorting (vps) mutants, including a differential delay in growth and vacuolar protein maturation, partial missorting of a soluble vacuolar hydrolase, and alterations in vacuole acidification and morphology. In fact, vps21 represents a mutant allele of YPT51 (Emr, S., personal communication). Altogether, these data suggest that Ypt51p, Ypt52p, and Ypt53p are required for transport in the endocytic pathway and for correct sorting of vacuolar hydrolases suggesting a possible intersection of the endocytic with the vacuolar sorting pathway.

The authors investigated whether expression of c-Met protein in glioblastomas is associated with overall survival and biologic features representing tumor invasiveness in patients with glioblastomas.Paraffin-embedded specimens of glioblastomas from 62 patients treated in a single institution were assessed by immunohistochemical (IHC) analysis of c-Met expression. On the basis of the clinical data for these patients, the association between c-Met expression and clinicobiologic features representing tumor invasiveness was analyzed.c-Met overexpression was detected in 29.0% (18 of 62) of glioblastomas. In patients with c-Met overexpression, the median survival was 11.7 months (95% confidence interval [95% CI], 9.9 months-13.5 months), compared with a median survival of 14.3 months (95% CI, 7.6 months-21.0 months) for patients whose tumors had no or little expression of c-Met (P=.031). On the radiographic analysis, 9 of 18 patients (50%) with tumors overexpressing c-Met demonstrated invasive and multifocal lesions on the initial magnetic resonance images, whereas only 9 of 44 patients (20.5%) with tumors that expressed no or little c-Met demonstrated these features (P=.030). Using immunohistochemistry, we also found a significant association between c-Met expression and matrix metalloproteinase-2,-9 (P=.020 and P=.013). Furthermore, Myc overexpression was found to be closely correlated with c-Met overexpression on IHC analysis (P=.004).The authors suggest that c-Met overexpression is associated with shorter survival time and poor treatment response in glioblastomas, the mechanism for which is elevated tumor invasiveness on the molecular and clinical phenotypes. This implies that more effective therapeutic strategies targeting c-Met receptors may have important clinical implication.

2522 Background: Tanibirumab is a fully human monoclonal antibody to the vascular endothelial growth factor receptor 2 (VEGFR-2). We conducted a first-in-human phase I study of Tanibirumab in patie...

To analyze the role of coat protein type II (COPII) coat components and targeting and fusion factors in selective export from the endoplasmic reticulum (ER) and transport to the Golgi, we have developed three novel, stage-specific assays. Cargo selection can be measured using a "stage 1 cargo capture assay," in which ER microsomes are incubated in the presence of glutathione S-transferase (GST)-tagged Sar1 GTPase and purified Sec23/24 components to follow recruitment of biosynthetic cargo to prebudding complexes. This cargo recruitment assay can be followed by two sequential assays that measure separately the budding of COPII-coated vesicles from ER microsomes (stage 2) and, finally, delivery of cargo-containing vesicles to the Golgi (stage 3). We show how these assays provide a means to identify the snap receptor (SNARE) protein rBet1 as an essential component that is not required for vesicle formation, but is required for vesicle targeting and fusion during ER-to-Golgi transport. In general, these assays provide an approach to characterize the biochemical basis for the recruitment of a wide variety of biosynthetic cargo proteins to COPII vesicles and the role of different transport components in the early secretory pathway of mammalian cells.

The trans-Golgi network (TGN) plays a pivotal role in directing proteins in the secretory pathway to the appropriate cellular destination. VAMP4, a recently discovered member of the vesicle-associated membrane protein (VAMP) family of trafficking proteins, has been suggested to play a role in mediating TGN trafficking. To better understand the function of VAMP4, we examined its precise subcellular distribution. Indirect immunofluorescence and electron microscopy revealed that the majority of VAMP4 localized to tubular and vesicular membranes of the TGN, which were in part coated with clathrin. In these compartments, VAMP4 was found to colocalize with the putative TGN-trafficking protein syntaxin 6. Additional labeling was also present on clathrin-coated and noncoated vesicles, on endosomes and the medial and trans side of the Golgi complex, as well as on immature secretory granules in PC12 cells. Immunoprecipitation of VAMP4 from rat brain detergent extracts revealed that VAMP4 exists in a complex containing syntaxin 6. Converging lines of evidence implicate a role for VAMP4 in TGN-to-endosome transport.

The exocyst is a protein complex required for the late stages of secretion in yeast. Unlike the SNAREs (SNAP receptors), important secretory proteins that are broadly distributed on the target membrane, the exocyst is specifically located at sites of vesicle fusion. We have isolated cDNAs encoding the rexo70, rsec5, and rsec15 subunits of the mammalian complex. The amino acid sequences encoded by these genes are between 21% and 24% identical to their yeast homologs. All three genes are broadly expressed and multiple transcripts are observed for rexo70 and rsec15. Characterization of cDNAs encoding the 84-kDa subunit of the mammalian complex revealed a novel protein. mAbs were generated to the mammalian rsec6 subunit of the exocyst complex. rsec6 immunoreactivity is found in a punctate distribution at terminals of PC12 cell processes at or near sites of granule exocytosis.

Tumor angiogenesis is the process that leads to the formation of blood vessels in a tumor and a prognostic indicator in various cancers. Vascular endothelial growth factor (VEGF) and its receptors are considered to be primary regulators of tumor-induced angiogenesis and activation of VEGFR2/KDR is the major signaling pathway for tumor growth. In addition, VEGFR2/KDR is also expressed in many cancer cells, and regulates cell growth and survival through autocrine pathway. In this study, we evaluated the therapeutic potential of TTAC-0001, fully human antibody against VEGFR2/KDR, for the inhibition of tumor growth. In the tube formation assay using HUVEC, TTAC-0001 exhibited a potent anti-angiogenic activity in vitro. In U-87 MG glioblastoma cells, TTAC-0001 significantly inhibited the phosphorylation of VEGFR2/KDR mediated by VEGF. To reveal in vivo efficacy, we have tested TTAC-0001 in glioblastoma and colorectal xenograft models. We demonstrated that antitumor activity of TTAC-0001 in preclinical models correlated with induction of growth arrest and apoptosis as well as the inhibition of angiogenesis. Currently, we are evaluating the combination of TTAC-0001 with chemotherapeutic agents in xenograft models. A single dose study performed in mouse allowed us to establish the relationship between the pharmacokinetics (PK) and efficacy of TTAC-0001. Taken together, our data suggest that targeting VEGFR2 pathway by TTAC-0001 would be a promising candidate for the treatment of cancer. (This study was supported by grants of the Korea Healthcare technology R&D Project, Ministry for Health & Welfare Affairs (A092255 and A040016) and Advanced Medi-cluster R&D Project, DaejeonTechnoPark, Republic of Korea. Seol HJ and Nam DH are co-corresponding authors for this manuscript.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 647. doi:10.1158/1538-7445.AM2011-647

Angiogenesis, the recruitment of new blood vessels is a crucial mechanism required for both tumor growth and metastasis. Vascular endothelial growth factor (VEGF) and its receptors, particularly VEGF receptor 2 (VEGFR2, or kinase insert domain-containing receptor, KDR), play a critical role in tumor-associated angiogenesis. Monoclonal antibodies (mAb), due to their high specificity towards a given target, represent a unique class of novel therapeutics as angiogenesis inhibitors. We developed TTAC-0001, anti-KDR antibody from a fully human naïve single chain variable fragment (ScFv) phage library. Interestingly, TTAC-0001 displayed cross reactivity against murine homologue, Flk-1, which allows us to evaluate the anti-tumor efficacy in various in vivo models. TTAC-0001 inhibits VEGF-mediated proliferation and migration. In HUVEC, TTAC-0001 inhibited the phosphorylation of VEGFR2/KDR and ERK mediated by VEGF. TTAC-0001 inhibited VEGF-mediated sprouting endothelial cells from rat aortic rings and showed a potent anti-angiogenic activity in VEGF-mediated matrigel model in nude mice. Further in vivo anti-tumor efficacy of TTAC-0001 was seen in the xenografts of A549 (lung) and HCT116 (colorectal) human cancer. These changes were accompanied by the inhibition of microvessel density and induction of apoptosis in the tumors. In summary, our data indicates that TTAC-0001 blocks the binding of VEGF to VEGFR2/KDR and inhibits VEGFR-induced angiogenesis. Therefore, this data strongly supports for the further development of TTAC-0001 as an anti-cancer agent (This study was supported by grants of the Korea Healthcare technology R&D Project, Ministry for Health & Welfare Affairs (A092255 and A040016) and Advanced Medi-cluster R&D Project, Daejeon TechnoPark, Republic of Korea). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4244. doi:10.1158/1538-7445.AM2011-4244