Einsatz verschiedener chromatographischer Verfahren zur Aufreinigung des integralen Membranproteins Lysophosphatidylcholin:Acyl-CoA-O- Acyltransferase

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Phase 1 dose-escalation study of the antiplacental growth factor monoclonal antibody RO5323441 combined with bevacizumab in patients with recurrent glioblastoma

Background We conducted a phase 1 dose-escalation study of RO5323441, a novel antiplacental growth factor (PlGF) monoclonal antibody, to establish the recommended dose for use with bevacizumab and to investigate the pharmacokinetics, pharmacodynamics, safety/tolerability, and preliminary clinical efficacy of the combination. Methods Twenty-two participants with histologically confirmed glioblastoma in first relapse were treated every 2 weeks with RO5323441 (625 mg, 1250 mg, or 2500 mg) plus bevacizumab (10 mg/kg). A standard 3 + 3 dose-escalation trial design was used. Results RO5323441 combined with bevacizumab was generally well tolerated, and the maximum tolerated dose was not reached. Two participants experienced dose-limiting toxicities (grade 3 meningitis associated with spinal fluid leak [1250 mg] and grade 3 cerebral infarction [2500 mg]). Common adverse events included hypertension (14 participants, 64%), headache (12 participants, 55%), dysphonia (11 participants, 50%) and fatigue (6 participants, 27%). The pharmacokinetics of RO5323441 were linear, over-the-dose range, and bevacizumab exposure was unaffected by RO5323441 coadministration. Modulation of plasmatic angiogenic proteins, with increases in VEGFA and decreases in FLT4, was observed. Dynamic contrast-enhanced/diffusion-weighted MRI revealed large decreases in vascular parameters that were maintained through the dosing period. Combination therapy achieved an overall response rate of 22.7%, including one complete response, and median progression-free and overall survival of 3.5 and 8.5 months, respectively. Conclusion The toxicity profile of RO5323441 plus bevacizumab was acceptable and manageable. The observed clinical activity of the combination does not appear to improve on that obtained with single-agent bevacizumab in patients with recurrent glioblastom

Solubilization, partial purification and photolabeling of the integral membrane protein lysophospholipid:acyl‐CoA acyltransferase (LAT)

In the present study, we defined experimental conditions that allowed the extraction of the integral membrane protein lysophospholipid:acyl-CoA acyltransferase (LAT, EC 2.3.1.23) from membranes while maintaining the full enzyme activity using the nonionic detergent n-octyl glucopyranoside (OGP) and solutions of high ionic strength. We found that the optimal OGP concentration depended on the ionic strength of the solubilization buffer. Fluorescence measurements with 1,6-diphenyl-1,3,5-hexatriene indicated that the critical micellar concentration (CMC) of OGP decreased with increasing salt concentrations. Analogous studies revealed that the zwitterionic detergent Chaps was ineffective in extracting LAT from membranes in the absence of salt, whereas its solubilization efficiency increased with increasing salt concentrations. Detailed lipid analysis of the different protein/lipid/detergent mixed micelles showed that the protein/lipid/OGP mixed micelles were relatively enriched with sphingomyelin (SPM) compared to protein/lipid/Chaps mixed micelles, indicating that the differences in the solubilization efficiency may be due to the ability to extract more SPM from membranes. When the protein/lipid/OGP mixed micelles were dissociated into protein/detergent and lipid/detergent complexes by the addition of increasing Chaps concentrations, one-tenth of the LAT enzyme activity was preserved making the enzyme accessible to protein purification. Analysis by native PAGE revealed that in the presence of excess Chaps a high molecular mass protein complex migrated into the gel which could be photolabeled by I-125-labelled-18-(4'-azido-2'-hydroxybenzoylamino)-oleyl-CoA. This fatty acid analogue has been shown to be a competitive inhibitor of LAT enzyme activity in the dark, and an irreversible inhibitor after photolysis. Therefore, this protein complex is assumed to contain the LAT enzyme

Abstract 4719: Exploratory biomarker program in Phase I clinical development of RG7155, a novel humanized anti-CSF-1R Mab, targeting Tumor Associated Macrophages (TAMs).

Abstract Early Phase I clinical development of RG7155, a humanized anti-CSF-1R monoclonal antibody binding to dimerization interface of CSF-1 receptor and inducing apoptosis in CSF-1R expressing macrophages is accompanied by an extensive biomarker program. Phase I biosampling aims to enable monitoring of mode of action, drug efficacy and potential tumor escape mechanisms by identifying response prediction and mechanistic efficacy markers and therefore to support optimal biological dose (OBD) definition and patient stratification for subsequent clinical testing. One biomarker hypothesis to support potential patient stratification assumes that response to treatment with RG7155 is enhanced in tumors with high CSF-1R positive macrophage infiltration and with high CSF-1 levels in the peripheral blood as the basis for tumor promoting macrophage recruitment and differentiation. The Phase I biomarker program comprises extensive biosampling including mandatory fresh baseline and on treatment tumor, skin biopsies as well as peripheral blood sampling to identify and monitor pharmacodynamic as well as mechanistic efficacy markers. Pre- and on-treatment tumor tissue analysis involves tumor infiltrating macrophage subtype characterization via CD68/CD163/CSF-1R/MHC II, CD4 and CD8 T cell assessment by multiplex IHC assays. In order to detect early tissue response prediction markers in surrogate tissue, wound associated macrophages (WAMs) are assessed in wounded skin tissue samples. Further, systematic collection of peripheral blood samples before and during RG7155 administration aims at identifying CSF-1R expressing target populations, other potential RG7155 susceptible immune cell populations by flow cytometry using CD8/CD4/CD3/CD45/MHC II/CD14/CD16/CD56/CD19 markers and an extended cytokine profiling by Luminex 17-plex panel. These markers will be correlated to direct anti-tumor effects assessed using KI67 IHC, FDG-PET, DC-Ultrasound and clinical response. Here we describe the development of the clinical biomarker strategy based on preclinical data and the specific assay developments, to enable the selection of the OBD, the correlation of TAM elimination with anti-tumor effects and the optimization of the biomarker sampling to minimize the burden of diagnostic procedures for patients in future clinical trials. Citation Format: Michael A. Cannarile, Kai Habben, Florian Heil, Ann-Marie Broeske, Dominik Ruettinger, Lisa Culton, Friedrich Feuerhake, Carola H. Ries. Exploratory biomarker program in Phase I clinical development of RG7155, a novel humanized anti-CSF-1R Mab, targeting Tumor Associated Macrophages (TAMs). [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 4719. doi:10.1158/1538-7445.AM2013-4719</jats:p

Standardization of HER2 testing: results of an international proficiency-testing ring study

Human epidermal growth factor receptor 2 (HER2) positivity in breast cancer is a prognostic factor regarding tumor aggressiveness and a predictive factor for response to trastuzumab (Herceptin). Early and accurate HER2 testing of all breast cancer patients at primary diagnosis is essential for optimal disease management. Routine HER2 tests, such as immunohistochemistry and fluorescence in situ hybridization (FISH), are subject to interlaboratory variation, and validation by laboratory proficiency testing is important to improve standardization. This study compared immunohistochemistry and FISH testing between five international pathology reference centers. Each center evaluated 20 immunohistochemistry and 20 FISH breast cancer specimens in five testing rounds. In each round, one center selected two sets of four different invasive tumor specimens (set A for immunohistochemistry and set B for FISH) and sent samples to the other four centers in a blinded manner, while retaining samples for its own evaluation. Results were analyzed by an independent coordinator. With immunohistochemistry, there were no differences between the five centers for any of the specimens at the level of diagnostic decision (positive or negative HER2 status). However, differences between laboratories were observed in immunohistochemistry scoring. Of the 20 specimens, four were scored as negative (0/1+) and five as positive (3+) in all centers; eight were negative or equivocal (2+), and three positive or equivocal. After FISH retesting of nine of the 11 equivocal immunohistochemistry cases, consensus was achieved in 15 of 18 (83%) specimens. FISH analysis of set B specimens resulted in consensus between centers in 16 of 20 (80%) specimens (six negative and 10 positive). All four discordant FISH specimens were scored as having HER2:CEP17 ratios within the range 1.7-2.3 by at least one center. Equivocal immunohistochemistry and borderline FISH cases are difficult to interpret, even for highly experienced and validated laboratories, highlighting the need for quality-control procedure

A Phase I Study of Weekly R1507, A Human Monoclonal Antibody Insulin-like Growth Factor-I Receptor Antagonist, in Patients with Advanced Solid Tumors

Abstract Purpose: A phase I study was conducted to evaluate the pharmacokinetics, pharmacodynamics, safety, and tolerability of R1507—a fully human IgG1 type monoclonal antibody directed against the human insulin-like growth factor-I receptor. Experimental design: Patients with advanced solid tumors were assigned to receive i.v. R1507 weekly (qW), starting with 1 mg/kg. Subsequent cohorts were dosed at 3 and then 9 mg/kg. An additional 12 patients received 9 mg/kg R1507 qW. Patients remained on the study until the development of a dose-limiting toxicity or progressive disease. Results: In total, 37 patients were treated with R1507 qW. No dose-limiting toxicities were identified and the maximum tolerated dose was not reached. The pharmacokinetics of R1507 were characterized by a slow clearance and limited volume of distribution, with an estimated elimination half-life justifying weekly administration. Serum IGF-I ligand levels increased proportionally to dose during the first 72 hours in all cohorts. R1507 was well tolerated. Two patients diagnosed with Ewing's sarcoma had partial responses of 11.5 and &amp;gt;26 months (ongoing at time of submission); 13 patients had stable disease; and 16 had progressive disease as best response by the Response Evaluation Criteria in Solid Tumors. Conclusion: R1507 is well tolerated and shows antitumor activity in patients with solid neoplasms, in particular Ewing's sarcoma. The recommended dose for the weekly schedule is 9 mg/kg qW. Clin Cancer Res; 16(8); 2458–65. ©2010 AACR.</jats:p

Phase I study of anti-PlGF monoclonal antibody (mAb) RO5323441 (RO) and anti-VEGF mab bevacizumab (BV) in patients with recurrent glioblastoma (GBM).

2092 Background: BV inhibits VEGF and is approved for progressive GBM following prior therapy. The placental growth factor (PlGF) is a member of the VEGF family and PlGF expression has been shown to correlate with tumor stage and survival in several human malignancies. In cancer patients (pts) PlGF is up-regulated upon treatment with VEGF inhibitors. RO is a humanized IgG1 mAb directed against PlGF that has demonstrated antitumor activity in an orthotopic GBM model. Single agent RO was previously tested in advanced solid tumors. Methods: Eligibility criteria included histologically confirmed GBM with documented radiographic progression upon front line therapy, ≥18 years of age, KPS ≥70, adequate bone marrow reserve and organ function. Prior treatment with VEGF/PLGF targeted therapies was not permitted. Three to six pts were enrolled per dose level (DL), the MTD defined as the dose with DLTs ≤ 1/6 pts during 28-days of cycle 1, using CTCAE v4. Results: A total of 22 pts (16m/6f) have been enrolled in 3 DLs: RO 625mg (4 pts), 1250mg (6), and 2500mg (12) IV every 2 weeks (q2w), each in combination with BV 10mg/kg IV q2w. Median age: 58 years (range 37-72). RO serum concentrations increased proportionally, while serum exposures of BV were similar between all DLs. Two pts experienced a DLT: Meningitis G3 (1250 mg) and cerebral infarction G3 (2500 mg). Most commonly reported adverse events included hypertension (14 pts), headache (11), dysphonia (10), fatigue (6), nasopharyngitis (5), epistaxis (4), constipation (4), nausea (3), and arthralgia (3). Across all DLs tested, the overall response rate by RANO criteria was 22.7%. Conclusions: The tolerability of RO in combination with BV is acceptable; a MTD was not determined. Anti-PlGF treatment does not appear to add on clinical activity observed for single agent BV in recurrent GBM. Clinical trial information: NCT01308684. </jats:p