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Purpose: This study investigated the safety, clinical activity, and target-associated biomarkers of lumretuzumab, a humanized, glycoengineered, anti-HER3 monoclonal antibody (mAb), in combination with the EGFR-blocking agents erlotinib or cetuximab in patients with advanced HER3-positive carcinomas.Experimental Design: The study included two parts: dose escalation and dose extension phases with lumretuzumab in combination with either cetuximab or erlotinib, respectively. In both parts, patients received lumretuzumab doses from 400 to 2,000 mg plus cetuximab or erlotinib according to standard posology, respectively. The effect of HRG mRNA and HER3 mRNA and protein expression were investigated in a dedicated extension cohort of squamous non–small cell lung cancer (sqNSCLC) patients treated with lumretuzumab and erlotinib.Results: Altogether, 120 patients were treated. One dose-limiting toxicity (DLT) in the cetuximab part and two DLTs in the erlotinib part were reported. The most frequent adverse events were gastrointestinal and skin toxicities, which were manageable. The objective response rate (ORR) was 6.1% in the cetuximab part and 4.2% in the erlotinib part. In the sqNSCLC extension cohort of the erlotinib part, higher tumor HRG and HER3 mRNA levels were associated with a numerically higher disease control rate but not ORR.Conclusions: The toxicity profile of lumretuzumab in combination with cetuximab and erlotinib was manageable, but only modest clinical activity was observed across tumor types. In the sqNSCLC cohort, there was no evidence of meaningful clinical benefit despite enriching for tumors with higher HRG mRNA expression levels. Clin Cancer Res; 23(18); 5406–15. ©2017 AACR.

Figure 1 Mean ({plus minus}SD) serum lumretuzumab profiles following multiple ascending doses from 100 mg up to 2000 mg Figure 2 Percentage change in standardized uptake value maximum from baseline as assessed by FDG-PET at (a) Cycle 1 Day 14 and (b) Cycle 4 Day 14 Table 1 Summary of baseline and change in HER3 expression measured by IHC in skin and tumor biopsy samples pre and post treatment with lumretuzumab Table 2 Summary of change in expression of HER3, HER2, EGFR and cMET in fresh tumor biopsies compared to primary archival samples Table 3 Peripheral blood immunophenotyping (T, B and NK cells and NK subsets) from patients dosed with 2000 mg lumretuzumab Table 4 Ex-vivo activation potential of peripheral NK lymphocytes for all patients at ba seline and following exposure to lumretuzumab in the 2000 mg dose cohort Table 5 Summary of tumor immune effector cell infiltration Table 6 Tumor response to treatment (RECIST)

Supplementary Table 1 Downregulation of HER3 membrane protein expression in skin biopsies following treatment with lumretuzumab and cetuximab or erlotinib Supplementary Table 2 Change of tumor biomarkers in tumor biopsies following treatment with lumretuzumab and cetuximab or erlotinib

Purpose: We evaluated biodistribution and tumor targeting of 89Zr-lumretuzumab before and during treatment with lumretuzumab, a human epidermal growth factor receptor 3 (HER3)–targeting monoclonal antibody.Experimental Design: Twenty patients with histologically confirmed HER3-expressing tumors received 89Zr-lumretuzumab and underwent positron emission tomography (PET). In part A, 89Zr-lumretuzumab was given with additional, escalating doses of unlabeled lumretuzumab, and scans were performed 2, 4, and 7 days after injection to determine optimal imaging conditions. In part B, patients were scanned following tracer injection before (baseline) and after a pharmacodynamic (PD)-active lumretuzumab dose for saturation analysis. HER3 expression was determined immunohistochemically in skin biopsies. Tracer uptake was calculated as standardized uptake value (SUV).Results: Optimal PET conditions were found to be 4 and 7 days after administration of 89Zr-lumretuzumab with 100-mg unlabeled lumretuzumab. At baseline using 100-mg unlabeled lumretuzumab, the tumor SUVmax was 3.4 (±1.9) at 4 days after injection. SUVmean values for normal blood, liver, lung, and brain tissues were 4.9, 6.4, 0.9 and 0.2, respectively. Saturation analysis (n = 7) showed that 4 days after lumretuzumab administration, tumor uptake decreased by 11.9% (±8.2), 10.0% (±16.5), and 24.6% (±20.9) at PD-active doses of 400, 800, and 1,600 mg, respectively, when compared with baseline. Membranous HER3 was completely downregulated in paired skin biopsies already at and above 400-mg lumretuzumab.Conclusions: PET imaging showed biodistribution and tumor-specific 89Zr-lumretuzumab uptake. Although, PD-active lumretuzumab doses decreased 89Zr-lumretuzumab uptake, there was no clear evidence of tumor saturation by PET imaging as the tumor SUV did not plateau with increasing doses. Clin Cancer Res; 23(20); 6128–37. ©2017 AACR.

Purpose: A first-in-human phase I study was conducted to characterize safety, efficacy, and pharmacokinetic (PK) and pharmacodynamic (PD) properties of lumretuzumab, a humanized and glycoengineered anti-HER3 monoclonal antibody, in patients with advanced cancer.Experimental Design: Twenty-five patients with histologically confirmed HER3-expressing tumors received lumretuzumab (100, 200, 400, 800, 1,600, and 2,000 mg) every two weeks (q2w) in 3+3 dose-escalation phase. In addition, 22 patients were enrolled into an extension cohort at 2,000 mg q2w.Results: There were no dose-limiting toxicities. Common adverse events (any grade) included diarrhea (22 patients, 46.8%), fatigue (21 patients, 44.7%), decreased appetite (15 patients, 31.9%), infusion-related reactions (13 patients, 27.7%), and constipation (10 patients, 21.3%). The peak concentration (Cmax) and area under the concentration–time curve up to the last measurable concentration (AUClast) of lumretuzumab increased more than dose proportionally from 100 mg up to 400 mg. Linear PK was observed with doses ≥400 mg q2w indicating target-mediated drug disposition saturation. Downregulation of HER3 membranous protein was observed in on-treatment tumor biopsies from 200 mg, and was maximal at and above 400 mg. An ex vivo assay demonstrated increased activation potential of peripheral NK lymphocytes with lumretuzumab compared with a non-glycoengineered anti-HER3 antibody. Ten patients (21.3%) had stable disease and remained on study at a median of 111 days (range, 80–225 days).Conclusions: Lumretuzumab was well tolerated and showed evidence of clinical activity. Linear serum PK properties and plateauing of PD effects in serial tumor biopsies indicate optimal biologically active doses of lumretuzumab from 400 mg onwards. Clin Cancer Res; 22(4); 877–85. ©2015 AACR.

Supplemental Figures and Tables

Figure 1 Mean ({plus minus}SD) serum lumretuzumab profiles following multiple ascending doses from 100 mg up to 2000 mg Figure 2 Percentage change in standardized uptake value maximum from baseline as assessed by FDG-PET at (a) Cycle 1 Day 14 and (b) Cycle 4 Day 14 Table 1 Summary of baseline and change in HER3 expression measured by IHC in skin and tumor biopsy samples pre and post treatment with lumretuzumab Table 2 Summary of change in expression of HER3, HER2, EGFR and cMET in fresh tumor biopsies compared to primary archival samples Table 3 Peripheral blood immunophenotyping (T, B and NK cells and NK subsets) from patients dosed with 2000 mg lumretuzumab Table 4 Ex-vivo activation potential of peripheral NK lymphocytes for all patients at ba seline and following exposure to lumretuzumab in the 2000 mg dose cohort Table 5 Summary of tumor immune effector cell infiltration Table 6 Tumor response to treatment (RECIST)

Supplementary Figure 1 Quantile plots of baseline membrane HER3 IRS score (A) and HER3 mRNA log expression (B) in baseline FFPE tumor biopsy samples from patients with known adeno- and squamous cell carcinoma histology Supplementary Figure 2 Quantile plots of baseline membrane HER3 immuno-reactive scores in fresh FFPE tumor biopsies from NSCLC patients with non-squamous or squamous histology Supplementary Figure 3 Quantile plots of baseline HRG mRNA log expression determined by qRT-PCR in FFPE tumor biopsies of adeno- and squamous cell carcinoma histology (data obtained using the HRG research assay) Supplementary Figure 4 Baseline HRG mRNA log expression in FFPE tumor biopsies, determined by qRT-PCR, in non-sqNSCLC and sqNSCLC (data obtained using the HRG prototype diagnostic assay). Dotted line indicates prior determined median HRG expression in sqNSCLC. Supplementary Figure 5 Best percentage change from baseline in sum of longest diameters of target lesions for patients in the dose escalation and extension phase of the cetuximab part (n = 38). Red bars indicate PD patients, blue bars SD patients, light green bars PR patients and dark green bars CR patients. Eleven patients were without target lesion assessment post baseline. Tumor type and lumretuzumab dose are indicated. * indicates patients who received previous EGFR-targeting therapy. a indicates a patient who received prior trastuzumab therapy. Supplementary Figure 6 Best percentage change from baseline in sum of longest diameters of target lesions for patients in the dose escalation phase and the two NRG1 fusion gene patients of the extension phase of the erlotinib part (n = 31). Red bars indicate PD patients, blue bars SD patients and green bars PR patients. Eight patients were without target lesion assessment post baseline. Tumor type and lumretuzumab dose are indicated. * indicates patients who received previous EGFR-targeting therapy. a indicates two patients with NRG1 gene fusion.

Combination of targeted therapies is expected to provide superior efficacy in the treatment of cancer either by enhanced antitumor activity or by preventing or delaying the development of resistance. Common challenges in developing combination therapies include the potential of additive and aggravated toxicities associated with pharmacologically related adverse effects. We have recently reported that combination of anti-HER2 and anti-HER3 antibodies, pertuzumab and lumretuzumab, along with paclitaxel chemotherapy in metastatic breast cancer, resulted in a high incidence of diarrhea that ultimately limited further clinical development of this combination. Here, we further dissected the diarrhea profile of the various patient dose cohorts and carried out in vitro investigations in human colon cell lines and explants to decipher the contribution and the mechanism of anti-HER2/3 therapeutic antibodies to intestinal epithelium malfunction. Our clinical investigations in patients revealed that while dose reduction of lumretuzumab, omission of pertuzumab loading dose, and introduction of a prophylactic antidiarrheal treatment reduced most severe adverse events, patients still suffered from persistent diarrhea during the treatment. Our in vitro investigations showed that pertuzumab and lumretuzumab combination treatment resulted in upregulation of chloride channel activity without indication of intestinal barrier disruption. Overall, our findings provide a mechanistic rationale to explore alternative of conventional antigut motility using medication targeting chloride channel activity to mitigate diarrhea of HER combination therapies. Mol Cancer Ther; 17(7); 1464–74. ©2018 AACR.

This study aimed at evaluating if pharmacokinetic and pharmacodynamic data from the first few patients treated with an investigational monoclonal antibody in a dose-escalation study can be used to guide the early initiation of potentially more efficacious combination regimens. Emerging pharmacokinetic and pharmacodynamic data from the first nine patients treated with lumretuzumab (a glycoengineered anti-HER3 monoclonal antibody) monotherapy at doses from 100 to 400 mg q2w were used along with a pharmacokinetic model that incorporated target-mediated drug disposition to guide the selection of the starting dose for use in combination regimens. The dose-escalation study investigated lumretuzumab doses up to 2000 mg q2w and a maximum tolerated dose was not reached. However, the model described in this report predicted linear lumretuzumab pharmacokinetics and >95% target saturation at doses ≥400 mg q2w. These data, along with safety data, contributed to the decision to begin dose-escalation studies in combination with cetuximab and erlotinib using a starting dose of 400 mg lumretuzumab. Pharmacokinetic data from patients treated with lumretuzumab 400–2000 mg q2w in combination regimens were consistent with the model predictions. PK/PD modelling of emerging clinical data might accelerate development programs by enabling additional parts of a trial to commence before completion of the monotherapy part. The dose and schedule of lumretuzumab were optimised for concomitant therapy at doses substantially below the highest dose investigated.

Background: Inhibition of HER2 and HER3 heterodimerisation is a novel treatment concept in HER2-”low” expressing breast cancer (BC). Lumretuzumab, a glycoengineered monoclonal anti-HER3 antibody, in combination with pertuzumab has demonstrated synergistic anti-tumor activity in preclinical HER2–low expressing preclinical BC models. Methods: This open-label, multicenter phase I study selectively enrolled metastatic BC patients (pts) expressing HER3 protein and low levels of HER2 (defined as IHC 1+ and 2+ and ISH-negative) in a formalin-fixed paraffin-embedded pretreatment tumor biopsy sample. Eligible pts were treated with a combination of paclitaxel (PA) qw plus lumretuzumab (L) and pertuzumab (P) q3w in three dose cohorts. The safety, antitumor activity and tumor biomarkers including protein expression (IHC, MS) and mutational data (NGS) in association with clinical activity were evaluated. Results: Overall, 35 pts were included in this study. The median age was 60 (range: 33 to 77) years. The median number of prior treatments for metastatic disease ranged from 0 to 5 with 23 pts (65.7%) without prior chemotherapy for metastatic disease. Cohort 1 was treated with PA at 80 mg/m2, L at 1000 mg and P at 840 mg for Cycle 1 followed by 420 mg for the following cycles. This cohort was stopped after two pts both experienced grade 3 diarrhea within the first treatment cycle which was considered a dose-limiting toxicity (DLT). For Cohort 2 the dose of L was reduced to 500 mg based on PK modelling and simulation data. No DLTs were seen for the first 6 pts. A total of 20 pts were recruited with an objective response rate (ORR) and disease control rate (DCR) of 30% and 75%, respectively, and 56% and 78%, respectively, for 1st-line pts (n=9) in this cohort. Diarrhea (≥G3) and hypokalemia (≥G3) occurred in 50% and 55% of pts, respectively, and all pts experienced chronic diarrhea throughout the course of treatment. For Cohort 3 the dose of L was maintained at 500 mg, PA at 80 mg/m2, and P was administered at 420 mg at all cycles. In addition, a prophylactic loperamide regimen was introduced. Altogether, 13 pts - all 1st-line for metastatic disease - were treated. No DLTs were seen for the first 6 pts. Diarrhea (≥G3) and hypokalemia (≥G3) were reduced to 31% and 15%, respectively, but chronic diarrhea was still observed throughout the treatment in all pts. The ORR and DCR were 31% and 77%, respectively. Preliminary mechanistic safety experiments revealed HER2/HER3-dependent chloride channels in the intestine as likely cause of diarrhea. Biomarker data will be presented along with updated clinical and safety data. Conclusions: The combination of L, P and PA was associated with high rates of persistent diarrhea. Dose modifications and prophylactic anti-diarrheal medication led to significantly reduced diarrhea intensity but did not change the incidence and persistence of diarrhea overall. Despite encouraging clinical activity especially in 1st line pts, the therapeutic window of this combination is too low to warrant further clinical development. Citation Format: Schneeweiss A, Park-Simon T-W, Albanell J, Lassen U, Cortes J, Dieras V, May M, Schindler C, Marmé F, Cejalvo JM, Martinez-Garcia M, Gonzalez I, Lopez-Martin J, Welt A, Joly F, Michielin F, Jacob W, Adessi C, Moisan A, Meneses-Lorente G, James I, Ceppi M, Hasmann M, Weisser M, Cervantes A. Phase Ib study evaluating the safety and clinical activity of lumretuzumab combined with pertuzumab and paclitaxel in HER2-low metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-11-13.

Purpose This study investigated the safety and clinical activity of lumretuzumab, a humanised antihuman epidermal growth factor receptor 3 (HER3) monoclonal antibody, in combination with carboplatin and paclitaxel in first-line treatment of patients with squamous non-small cell lung cancer (sqNSCLC). HER3 ligand heregulin and HER3 protein expression were evaluated as potential biomarkers of clinical activity. Patients and methods This open-label, phase Ib/II study enrolled patients receiving lumretuzumab at 800 mg (flat) in combination with carboplatin (area under the curve (AUC) 6 mg/mL×min) and paclitaxel (200 mg/m 2) administered intravenously on a every 3-week schedule. Adverse event (AE) rates and tumour responses were determined. Heregulin messenger RNA (mRNA) and HER3 protein expression were investigated in archival tumour biopsies. Results Altogether, 12 patients received lumretuzumab in combination with carboplatin and paclitaxel. The most frequent AEs were gastrointestinal, haematological and nervous system toxicities, which were generally mild and manageable. Partial responses were observed in 3 of 12 patients lasting 81, 177 and 207 days. All responses were achieved in tumours expressing higher heregulin mRNA levels. Conclusion Lumretuzumab in combination with carboplatin and paclitaxel was well tolerated. Objective responses were enriched in tumours expressing higher heregulin mRNA levels.

To inform lumretuzumab and pertuzumab dose modifications in order to decrease the incidence, severity, and duration of the diarrhea events in metastatic breast cancer patients treated with a combination therapy of lumretuzumab (anti-HER3) in combination with pertuzumab (anti-HER2) and paclitaxel using quantitative clinical pharmacology modeling approaches. The safety and pharmacokinetic (PK) data from three clinical trials (lumretuzumab monotherapy n = 47, pertuzumab monotherapy n = 78, and the combination therapy of lumretuzumab, pertuzumab and paclitaxel n = 35) were pooled together to develop a continuous-time discrete states Markov model describing the dynamics of the diarrhea events. The model was able to capture the time course of different severities of diarrhea reasonably well. The effect of lumretuzumab and pertuzumab was well described by an Emax function indicating an increased rate of transition from moderate to mild or more severe diarrhea with higher doses. The concentration needed to trigger or worsen diarrhea episodes was estimated to be 120-fold lower in combination therapy compared to monotherapy, suggesting strong synergy between the two monoclonal antibodies. The prophylactic effect of loperamide in a subset of patients was also well captured by the model with a clear tendency to reduce the occurrence of diarrhea events. This work shows that PK-toxicity modeling provides insight into how the severity of key adverse events evolves over time and highlights the potential use to support decision making in drug development.

Summary Purpose To investigate the safety and clinical activity of comprehensive human epidermal growth factor receptor (HER) family receptor inhibition using lumretuzumab (anti-HER3) and pertuzumab (anti-HER2) in combination with paclitaxel in patients with metastatic breast cancer (MBC). Methods This phase Ib study enrolled 35 MBC patients (first line or higher) with HER3-positive and HER2-low (immunohistochemistry 1+ to 2+ and in-situ hybridization negative) tumors. Patients received lumretuzumab (1000 mg in Cohort 1; 500 mg in Cohorts 2 and 3) plus pertuzumab (840 mg loading dose [LD] followed by 420 mg in Cohorts 1 and 2; 420 mg without LD in Cohort 3) every 3 weeks, plus paclitaxel (80 mg/m2 weekly in all cohorts). Patients in Cohort 3 received prophylactic loperamide treatment. Results Diarrhea grade 3 was a dose-limiting toxicity of Cohort 1 defining the maximum tolerated dose of lumretuzumab when given in combination with pertuzumab and paclitaxel at 500 mg every three weeks. Grade 3 diarrhea decreased from 50% (Cohort 2) to 30.8% (Cohort 3) with prophylactic loperamide administration and omission of the pertuzumab LD, nonetheless, all patients still experienced diarrhea. In first-line MBC patients, the objective response rate in Cohorts 2 and 3 was 55% and 38.5%, respectively. No relationship between HER2 and HER3 expression or somatic mutations and clinical response was observed. Conclusions Combination treatment with lumretuzumab, pertuzumab and paclitaxel was associated with a high incidence of diarrhea. Despite the efforts to alter dosing, the therapeutic window remained too narrow to warrant further clinical development. Trial registration: on ClinicalTrials.gov with the identifier NCT01918254 first registered on 3rd July 2013.

Purpose: This study investigated the safety, clinical activity, and target-associated biomarkers of lumretuzumab, a humanized, glycoengineered, anti-HER3 monoclonal antibody (mAb), in combination with the EGFR-blocking agents erlotinib or cetuximab in patients with advanced HER3-positive carcinomas.Experimental Design: The study included two parts: dose escalation and dose extension phases with lumretuzumab in combination with either cetuximab or erlotinib, respectively. In both parts, patients received lumretuzumab doses from 400 to 2,000 mg plus cetuximab or erlotinib according to standard posology, respectively. The effect of HRG mRNA and HER3 mRNA and protein expression were investigated in a dedicated extension cohort of squamous non–small cell lung cancer (sqNSCLC) patients treated with lumretuzumab and erlotinib.Results: Altogether, 120 patients were treated. One dose-limiting toxicity (DLT) in the cetuximab part and two DLTs in the erlotinib part were reported. The most frequent adverse events were gastrointestinal and skin toxicities, which were manageable. The objective response rate (ORR) was 6.1% in the cetuximab part and 4.2% in the erlotinib part. In the sqNSCLC extension cohort of the erlotinib part, higher tumor HRG and HER3 mRNA levels were associated with a numerically higher disease control rate but not ORR.Conclusions: The toxicity profile of lumretuzumab in combination with cetuximab and erlotinib was manageable, but only modest clinical activity was observed across tumor types. In the sqNSCLC cohort, there was no evidence of meaningful clinical benefit despite enriching for tumors with higher HRG mRNA expression levels. Clin Cancer Res; 23(18); 5406–15. ©2017 AACR.

Purpose: A first-in-human phase I study was conducted to characterize safety, efficacy, and pharmacokinetic (PK) and pharmacodynamic (PD) properties of lumretuzumab, a humanized and glycoengineered anti-HER3 monoclonal antibody, in patients with advanced cancer. Experimental Design: Twenty-five patients with histologically confirmed HER3-expressing tumors received lumretuzumab (100, 200, 400, 800, 1,600, and 2,000 mg) every two weeks (q2w) in 3+3 dose-escalation phase. In addition, 22 patients were enrolled into an extension cohort at 2,000 mg q2w. Results: There were no dose-limiting toxicities. Common adverse events (any grade) included diarrhea (22 patients, 46.8%), fatigue (21 patients, 44.7%), decreased appetite (15 patients, 31.9%), infusion-related reactions (13 patients, 27.7%), and constipation (10 patients, 21.3%). The peak concentration (Cmax) and area under the concentration–time curve up to the last measurable concentration (AUClast) of lumretuzumab increased more than dose proportionally from 100 mg up to 400 mg. Linear PK was observed with doses ≥400 mg q2w indicating target-mediated drug disposition saturation. Downregulation of HER3 membranous protein was observed in on-treatment tumor biopsies from 200 mg, and was maximal at and above 400 mg. An ex vivo assay demonstrated increased activation potential of peripheral NK lymphocytes with lumretuzumab compared with a non-glycoengineered anti-HER3 antibody. Ten patients (21.3%) had stable disease and remained on study at a median of 111 days (range, 80–225 days). Conclusions: Lumretuzumab was well tolerated and showed evidence of clinical activity. Linear serum PK properties and plateauing of PD effects in serial tumor biopsies indicate optimal biologically active doses of lumretuzumab from 400 mg onwards. Clin Cancer Res; 22(4); 877–85. ©2015 AACR.

Prions are the infectious agents associated with transmissible spongiform encephalopathies and are composed mainly of a misfolded form of the endogenous prion protein. Prion protein must enter the brain to produce disease. Previous work has emphasized various mechanisms which partially bypass the blood–brain barrier (BBB). Here, we used the brain perfusion method to directly assess the ability of mouse scrapie protein (PrP SC ) to cross the mouse BBB independent of the influences of neural pathways or circulating immune cells. We found that PrP SC oligomers rapidly crossed the BBB without disrupting it with a unidirectional influx rate of about 4.4 μl/g-min. HPLC and capillary depletion confirmed that PrP SC crossed the entire width of the capillary wall to enter brain parenchyma. PrP SC also entered the cerebrospinal fluid (CSF) compartment. These results show that a prion protein can cross the intact BBB to enter both the parenchymal and CSF compartments of the brain.

Amyloid plaques in brain, composed of aggregates of amyloid-beta peptide, play a central role in the pathogenesis of Alzheimer's disease and represent a good target for treatment. We have shown previously that a 5-amino acid beta-sheet breaker peptide (iA beta 5p), end-protected, has the ability to induce a dramatic reduction in amyloid deposition in two different transgenic Alzheimer's models (Permanne, B., Adessi, C., Saborio, G. P., Fraga, S., Frossard, M.-J., Dewachter, I., Van Dorpe, J., Banks, W. A., Van Leuven, F., and Soto, C. (2002) FASEB J. 16, 860-862). The aim of this study was to evaluate the effect of chemical modifications of the peptide bonds at the metabolite cleavage sites on the pharmacological properties of iA beta 5p derivatives. Using a rational approach, peptide analogs were designed and tested for in vitro activity and enzymatic stability. One peptide analog containing a methyl group introduced at the nitrogen atom of one amide bond showed increased stability in vitro, a 10-fold higher in vivo half-life, and good brain uptake compared with iA beta 5p while maintaining a similar activity in vitro. Our results suggest that the pharmacological profile of beta-sheet breaker peptides can be improved to produce compounds with drug-like properties that might offer a new promise in the treatment of Alzheimer's disease.

Alzheimer's disease is a degenerative disorder of the brain for which there is no cure or effective treatment. Recent studies suggest that cerebral amyloid plaques play a central role in the pathogenesis of the disease. An attractive therapeutic strategy for Alzheimer's disease is to block the early steps of misfolding and aggregation of the soluble amyloid-beta peptide. We have engineered synthetic β-sheet breaker peptides to bind amyloid-β peptide, stabilize the normal conformation, and destabilize the β-sheet rich structure that leads to the formation of amyloid plaques. Results in vitro, in cell culture, and in vivo suggest that β-sheet breaker peptide may be useful for blocking the process of cerebral amyloid deposition. Chemical modifications were introduced into the active peptides to improve their pharmacological properties. It remains to be proved that inhibition of the pathway leading to amyloid plaque deposition could be beneficial for the therapeutic treatment of Alzheimer's disease. Drug Dev. Res. 56:184–193, 2002. © 2002 Wiley-Liss, Inc.

We characterized the in vitro fusion of endosomal compartments from Dictyostelium discoideum. Fusion activity was restricted to early compartments, was dependent on cytosolic proteins, and was activated by GTP and guanosine 5'-O(3-thio)triphosphate (GTPgammaS). This stimulation suggests the involvement of a small G protein, which we propose to be Rab7 on the basis of the strong inhibitory effect of anti-Rab7 antibodies. It is noteworthy that in the presence of GTPgammaS, the concentration of ATP-Mg2+ could be reduced to less than 1 nM without loss of fusion activity. Under these conditions, competing residual ATP with adenosine 5'-O-(3-thio)triphosphate-Mg2+ also failed to inhibit endosome fusion. The presence of an ATP-depleting system alone blocked fusion probably because endogenous GTP was removed by coupling through NDP kinase. Moreover, whether ATP was present or not, GTPgammaS-activated fusion was equally sensitive to anti-Rab7 antibodies or N-ethylmaleimide and was restricted to early compartments. These results show that soluble ATP-Mg2+ is not needed for endosome fusion. Since homotypic fusion of endosomes in D. discoideum has been shown to depend on the ATPase N-ethylmaleimide-sensitive factor (Lenhard, J. M., Mayorga, L. , and Stahl, P. D. (1992) J. Biol. Chem. 267, 1896-1903), the nucleotide exchange on the N-ethylmaleimide sensitive factor must take place before GTPgammaS activation in this system.

11555Background: Lumretuzumab is a humanized, glycoengineered, monoclonal antibody targeting human epidermal growth factor receptor 3 (HER3), in phase Ib clinical development in patients with HER3-...

Genetic, neuropathological, and biochemical studies have provided strong evidence for a central role of amyloid in the pathogenesis of Alzheimer's disease (AD). We have proposed previously that peptides designed as beta-sheet breakers may be useful in preventing the formation of amyloid plaques. In this study, we describe a modified beta-sheet breaker peptide with improved pharmacological properties, a high rate of penetration across the blood-brain barrier, and the ability to induce a dramatic reduction in amyloid deposition in two different transgenic AD models. In addition, we report for the first time a significant increase in neuronal survival and a decrease in brain inflammation associated with the reduction of amyloid plaques. These results demonstrate that the process of amyloid deposition is one of the causes of neurodegeneration in AD. Moreover, our findings indicate that beta-sheet breaker peptides provide a valuable tool for evaluating further the importance of amyloid in the etiology of AD and suggest that these peptides or some of their derivatives might be good candidates for AD treatment.

The pathological role of ApoE4 in Alzheimer's disease (AD) is not fully elucidated yet but there is strong evidence that ApoE is involved in Abeta deposition, which is an early hallmark of AD neuropathology. Overexpression of ApoE in neuroblastoma cells (Neuro2a) leads to the generation of an intracellular 13 kDa carboxy-terminal fragment of ApoE comparable to fragments seen in brains of AD patients. ApoE4 generates more of this fragment than ApoE2 and E3 suggesting a potential pathological role of these fragments in Alzheimer's disease. Analysis of this intracellular ApoE4 fragment by protease digest followed by MALDI-TOF mass spectrometry showed the proteolytic cleavage site close to residue 187 of ApoE. We have engineered and expressed the corresponding ApoE fragments in vitro. The recombinant 13 kDa carboxy-terminal fragment inhibited fibril formation of Abeta; this contrasts with the full-length ApoE and the corresponding amino-terminal ApoE fragment. Moreover, we show that the 13 kDa carboxy-terminal fragment of ApoE stabilizes the formation of Abeta hexamers. Complexes of Abeta with the 13 kDa carboxy-terminal ApoE fragment show toxicity in PC12 cells comparable to Abeta fibrils. These data suggest that cleavage of ApoE, leading to the generation of this fragment, contributes to the pathogenic effect of ApoE4 in AD.

The discovery of peptide hormones, growth factors and neuropeptides implicated in vital biological functions of our organism has increased interest in therapeutic use of short peptides. However, the development of peptides as clinically useful drugs is greatly limited by their poor metabolic stability and low bioavailability, which is due in part to their inability to readily cross membrane barriers such as the intestinal and blood-brain barriers. The aim of peptide medicinal chemistry is, therefore, to develop strategies to overcome these problems. Recent progress in chemical synthesis and design have resulted in several strategies for producing modified peptides and mimetics with lower susceptibility to proteolysis and improved bioavailability, which has increased the probability of obtaining useful drugs structurally related to parent peptides. This review describes different experimental approaches to transforming a peptide into a potential drug and provides examples of the usefulness of these strategies.

Aim: To evaluate the safety profile of RG7116 in combination with cetuximab or erlotinib. Methods: Patients (pts) with advanced or metastatic carcinomas with centrally confirmed HER3 protein expression were included. RG7116 plus cetuximab (400 mg/m2 followed by 250 mg/m2 qw IV) and RG7116 plus erlotinib (150 mg/day p.o.) combinations were evaluated in a dose escalation study with “3 + 3” design at a starting dose of 400 mg IV of RG7116 in a q2w regimen. Results: Twenty-seven pts were enrolled in 5 cohorts (400 to 2000 mg) in the cetuximab arm. One dose-limiting toxicity (DLT) of grade 3 dehydration was reported in the 800-mg cohort. Twenty-seven pts were enrolled in 4 cohorts (400 to 2000 mg) in the erlotinib arm. One DLT was reported in the 1600-mg cohort (grade 3 diarrhea and grade 3 hypokalemia) and one DLT was reported in the 2000-mg cohort (grade 3 blood bilirubin increase). No maximum tolerated dose was reached. The most frequently reported adverse events of any grade were diarrhea (78%) and rash (59%) for the cetuximab arm and diarrhea (82%) and decreased appetite (48%) for the erlotinib arm. In the erlotinib arm treatment-related grade 3 diarrhea was observed more frequently at higher doses of RG7116 (400 mg: 0%; 800 mg: 17%; 1600 mg: 43%; 2000 mg: 33%). Overall, infusion-related reactions related to RG7116 occurred in 11% of pts. Two of these were grade 3 (4%). The pharmacokinetic profile of RG7116 in combination with cetuximab and erlotinib was comparable to that in the monotherapy setting (Meulendijks et al. J Clin Oncol 31, 2013 suppl; abstr 2522). HER3 membranous protein down-regulation was observed from 400 mg onwards in on-treatment tumor and skin tissue. In the cetuximab arm, two pts with colorectal carcinoma had a confirmed partial response (PR). In the erlotinib arm, one patient with ovarian carcinoma had a confirmed PR. Metabolic PR on FDG-PET occurred in 42% of pts in the cetuximab arm and in 28% of pts in the erlotinib arm. Conclusions: RG7116 combination with cetuximab or erlotinib was well tolerated, and demonstrated preliminary signs of clinical activity. Disclosure: U.N. Lassen: discloses Research grants from Roche; A. Cervantes Ruiperez: discloses Research grants, advisory boards and lectures for Roche; C. Adessi, A. Keelara, F. Michielin, B. Bossenmaier, G. Meneses-Lorente, I. James, W. Jacob and M. Weisser: Employee of Roche. All other authors have declared no conflicts of interest.

11095 Background: Human epidermal growth factor receptor 3 (HER3) can play a critical role in tumor growth, proliferation and progression. The glycoengineered humanized monoclonal HER3-targeting an...

Different chemical methods used to attach oligonucleotides by their 5'-end on a glass surface were tested in the framework of solid phase PCR where surface-bound instead of freely-diffusing primers are used to amplify DNA. Each method was first evaluated for its capacity to provide a high surface coverage of oligonucleotides essentially attached via a 5'-specific linkage that satisfyingly withstands PCR conditions and leaves the 3'-ends available for DNA polymerase activity. The best results were obtained with 5'-thiol-modified oligonucleotides attached to amino-silanised glass slides using a heterobifunctional cross-linker reagent. It was then demonstrated that the primers bound to the glass surface using the optimal chemistry can be involved in attaching and amplifying DNA molecules present in the reaction mix in the absence of freely-diffusing primers. Two distinct amplification processes called interfacial and surface amplification have been observed and characterised. The newly synthesised DNA can be detected and quantified by radioactive and fluorescent hybridisation assays. These new surface amplification processes are seen as an interesting approach for attachment of DNA molecules by their 5'-end on a solid support and can be used as an alternative route for producing DNA chips for genomic studies.

2522 Background: The Human Epidermal Growth Factor Receptor 3 (HER3) is a key heterodimerization partner for other HER family members thereby acting as a downstream signal amplifier. This is a first in human study evaluating the safety of RG7116, a humanized anti-HER3 monoclonal antibody with potent HER3 signal inhibition. Due to a glycoengineered Fc-part this antibody displays enhanced antibody-dependent cellular cytotoxicity as compared to conventional antibodies. Methods: Patients (pts) with advanced or metastatic carcinomas with centrally confirmed HER3 protein expression were included. A “3+3” dose escalation design was performed starting at 100 mg flat dosing in a q2w regimen. In addition to single agent RG7116 (Part A), RG7116 plus cetuximab (Part B) and RG7116 plus erlotinib (Part C) combinations are evaluated. The results of Part A are presented. Results: Twenty-five pts have been enrolled in 6 cohorts (100 to 2000 mg). No DLTs were observed. Pts had a median (range) of 3 (2 to 6) prior chemotherapy lines. Nine infusion-related reactions (IRRs) Gr 1 to 3 occurred in 7 pts. Three drug-related AEs Gr 3 were reported, 1 IRR, 1 GGT increase, and 1 neutropenia. Only 1 patient was tested positive for human anti human antibodies (HAHA). The PK of RG7116 was non-linear from 100 mg up to 400 mg, possibly as a result of target-mediated drug disposition. Both Cmax and AUC showed a greater than doseEproportional increase over the same dose range, accompanied by a decline in total clearance. Dose proportionality was observed from 800 mg onwards. PD effects were observed from the first dose level onwards with HER3 membranous protein down-regulation in skin and from 200 mg onwards in ontreatment tumor samples. Five pts (1 NSCLC, 2 CRC, 1 SCCHN, 1 BC) had a best response of SD. Confirmed SD (>16 weeks) was observed in 2 pts. One BC patient achieved a PR in 18 FDG-PET and significant shrinkage of non-target tumor lesions on CT scan. Conclusions: RG7116 is the first glycoengineered monoclonal anti-HER3 antibody in clinical development. RG7116 monotherapy was well tolerated, and demonstrated preliminary signs of clinical activity. Clinical trial information: NCT01482377.