Human Anti-human Antibody Research Articles

HGS-ETR2—A fully human monoclonal antibody to TRAIL-R2: Results of a phase I trial in patients with advanced solid tumors

3012 Background: HGS-ETR2 is a fully-human high-affinity monoclonal antibody that is agonistic to the Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Receptor 2 (TRAIL-R2, DR5). TRAIL-R2 is expressed more widely on the surface of tumor cells than normal cells; binding of HGS-ETR2 to TRAIL-R2 leads to activation of the extrinsic apoptosis pathway. HGS-ETR2 shows anti-tumor activity at doses ≥ 0.3 mg/kg in xenograft models, both as a single agent and in combination with chemotherapeutic agents. Methods: This phase 1, dose-escalation study assessed the safety, tolerability, pharmacokinetics and immunogenicity of HGS-ETR2 administered IV every 14 days in patients with advanced solid tumors. Patients received HGS-ETR2 until disease progression or unacceptable toxicity. Tumor measurements were repeated every 2 months. Results: To date, 31 patients have received 167 courses of HGS-ETR2 over 5 dose levels: 0.1, 0.3, 1.0, 3.0 and 10.0 mg/kg q14 days. The majority (26 of 31) received at least 4 courses. One patient experienced a dose-limiting toxicity of grade 3 hyperamylasemia at the 10 mg/kg dose level. The event was determined to be possibly related to HGS-ETR2 and also possibly related to a nutritional supplement. Stable disease was achieved in 10 patients for 4 to 16 cycles. One patient with chemotherapy-refractive Hodgkin’s disease had a tumor regression of abdominal disease. HGS-ETR2 pharmacokinetics were linear up to 10 mg/kg. At the 10 mg/kg dose, the pharmacokinetics were characterized by a mean (SD) t1/2β of 11 (4) days, CL of 6.0 (0.7) mL/day, and V1 of 47 (8) mL/kg, slightly larger than the plasma volume. The 1.8-fold larger Vss of 85 (27) mL/kg indicates that HGS-ETR2 distributes outside the plasma compartment. Human anti-human antibody formation has not been detected. Conclusions: HGS-ETR2 can be safely administered every 14 days at doses up to and including 10 mg/kg. Further evaluation of HGS-ETR2 is planned, including studies of HGS-ETR2 in combination with chemotherapeutic agents. [Table: see text]

Panitumumab antitumor activity in patients (pts) with metastatic colorectal cancer (mCRC) expressing ≥ 10% epidermal growth factor receptor (EGFr)

3548 Background: Panitumumab is a fully human monoclonal antibody directed against EGFr. We investigated panitumumab antitumor activity in pts who failed prior therapy and had EGFr tumor expression levels ≥ 10%. Methods: In this multicenter, phase 2 study of 300 planned pts, pts had documentation of disease progression (PD) during or following adequate doses of fluoropyrimidine, irinotecan, and oxaliplatin (centrally confirmed refractory disease [CCRD]), 2–3 prior regimens, ECOG score 0–2, and EGFr staining (by IHC) in ≥ 10% of evaluable tumor cells. Pts received panitumumab at 6 mg/kg Q2W until PD. Tumor assessments (modified WHO, blinded central review) were taken periodically from wk 8–48 until PD. Study endpoints were objective response rate (ORR) at wk 16 (+ ≥ 4 wk confirmation; primary) and ORR throughout study, response duration, progression-free survival (PFS) time, survival time, and safety (secondary). Results: In this interim analysis (5/05), 91 enrolled pts received ≥ 1 dose of panitumumab (safety set); 39 had ≥ 20 wks before the cutoff and CCRD (efficacy set). The efficacy set consisted of 23M/16W, mean (SD) age of 58.6 (10.1) years, 82% white, 95% ECOG ≤ 1, 74% colon cancer and 26% rectal cancer; all had ≥ 2 prior regimens (equivalent characteristics for safety set). At wk 16, 3 (8%) had a partial response, 8 (21%) had stable disease, and 19 (49%) had PD as best OR (9 not done/unevaluable). At the time of this interim analysis, response durations were 12.4, 13.2, and 14.0 wks. In the safety set, 96% had at least 1 treatment-related adverse event (24% grade [gr] 3, 1% gr 4, 1% gr 5). Integument and eye toxicities were: 96% skin, 30% nail, 8% eye, 5% hair, and 7% chelitis. 25 (27%) had diarrhea (3 gr 3); 11 (12%) had hypomagnesemia (3 gr 3/4). One pt had a gr 3 hypersensitivity reaction considered related to panitumumab, received medication, and the event resolved; this pt continued treatment with premedication; no further reactions occurred. In 66 pts with both a baseline and postdose sample, no human anti-human antibodies to panitumumab were detected.Additional data will be presented. Conclusions: Panitumumab has antitumor activity and is well tolerated in pts with EGFr tumor expression levels ≥ 10% who failed standard chemotherapy. [Table: see text]

Targeting Lewis Y (LeY) in small cell lung cancer (SCLC) with a humanized monoclonal antibody, hu3S193

7086 Background: LeY is a blood group antigen with dominant expression on the surface of epithelial tumors, including SCLC, making it a potential target for antibody-based immunotherapy. 3S193, an IgG3 mAb, has demonstrated superior specificity, affinity, and cytotoxicity over other anti-LeY antibodies. A phase I trial of humanized 3S193 (hu3S193) with dosing up to 40 mg/m2 demonstrated tumor targeting without serious toxicities or the development of human antihuman antibodies (Scott et al, ASCO, 2004). Methods: We tested the targeting and pharmacokinetics of hu3S193 in patients with SCLC. Eligibility required progressive SCLC treated with up to three prior chemotherapy regimens, measurable disease not previously irradiated, and tumor samples immunohistochemistry (IHC)-positive for 3S193. Patients received four weekly injections of hu3S193, 5 patients at 10mg/m2 and 5 patients at 20 mg/m2. The first and fourth injections were radiolabeled with 111Indium for gamma camera imaging. Results: Of 40 patients screened, 25/34 (74%) evaluable SCLC tumor samples were 3S193-positive by IHC: 1+ (n = 13), 2+ (n = 3), 3+ (n = 2), 4+ (n = 7). Ten patients were treated with hu3S193; eight completed all four injections (one had disease progression and one is still on treatment). At the lower dose, about 50% of lesions >2 cm diameter visualized on FDG-PET were also seen on 111In SPECT imaging. However, at the higher dose, essentially all FDG avid lesions showed targeting. The mean T1/2 for all infusions was 2.89 ± 0.84 days at 10 mg/m2 (n = 9) and 3.29 ± 0.66 days at 20 mg/m2 (n = 7). No difference was noted in imaging or pharmacokinetics between the first and fourth injections. At the 20 mg/m2 dose, patients experienced grade 2 urticaria (n = 1), grade 1 vomiting (n = 2), and grade 2 hypertension (n = 1) transiently after infusion. No other grade 2 or greater toxicities were observed. No objective responses were observed. Conclusions: SCLC has a high rate of Lewis Y expression. Given the strong tumor targeting, particularly at the higher dose, and the potential for immunomodulatory effects, administration of hu3S193 with chemotherapy would be warranted. Supported by the Ludwig Institute and the Experimental Therapeutics Committee of MSKCC. No significant financial relationships to disclose.

Panitumumab antitumor activity in patients (pts) with metastatic colorectal cancer (mCRC) expressing low (1–9%) or negative (<1%) levels of epidermal growth factor receptor (EGFr)

3547 Background: Panitumumab is a fully human monoclonal antibody directed against EGFr. We investigated the antitumor activity of panitumumab in pts with mCRC who failed prior therapy and had low or negative EGFr tumor expression. Methods: In this multicenter, phase 2 study of 150 planned pts, pts had documentation of disease progression (PD) during or after adequate doses of fluoropyrimidine, irinotecan, and oxaliplatin (centrally confirmed refractory disease [CCRD]), 2–3 prior regimens, ECOG score 0–2, and low or negative EGFr staining (by IHC) in evaluable tumor cells. Pts received panitumumab at 6 mg/kg Q2W until PD or drug intolerability. Tumor assessments (modified WHO, blinded central review) were taken periodically from wk 8 until PD. Endpoints were objective response (OR) through wk 16 (+ ≥ 4 wk confirmation; primary) and OR throughout study, response duration, progression-free survival (PFS) time, survival time, and safety (secondary). Results: In this interim analysis (6/05), 88 pts were enrolled and had ≥ 1 dose of panitumumab (safety set); 23 pts had ≥ 20 wks before the cutoff and CCRD (efficacy set). The efficacy set consisted of 16M/7W, median age of 65 (range: 46, 85) yrs, 83% white, 100% with ECOG ≤ 1, 74% colon cancer and 26% rectal cancer; all received ≥ 2 prior regimens (equivalent characteristics for safety set). 2/11 (18%) pts with EGFr-negative tumors and 1/12 (8%) with low EGFr staining had a partial response. Duration was up to 16 wks. 7/23 (30%) of all pts had SD. Median (95% CI) PFS was 7.9 (7.0, 23.0) wks. In the safety set, all pts had a treatment-related adverse event; 19% grade (gr) 3; 2% gr 4. Integument and eye toxicities were: 92% skin, 17% eye, 28% nail, 8% hair, and 2% chelitis. 20 (23%) had diarrhea (1 gr 3); 7 (8%) had hypomagnesemia (2 gr 3/4). Three pts had an infusion reaction-1 gr 3 (led to panitumumab discontinuation) and 2 gr 1/2. In 65 pts with both a baseline and post-baseline sample, no human anti-human antibodies to panitumumab were detected. Updated data will be presented. Conclusions: Responses to panitumumab were seen in pts with mCRC with both low and negative EGFr levels. Efficacy appears similar to that in other studies with panitumumab in pts with higher EGFr tumor levels. [Table: see text]

Qualification and application of a surface plasmon resonance-based assay for monitoring potential HAHA responses induced after passive administration of a humanized anti Lewis-Y antibody

A sensitive, surface plasmon resonance (SPR)-based assay monitoring potential human–anti-human antibody (HAHA) reactions against the monoclonal antibody (mAb) IGN311 is presented. The latter is a fully humanized Lewis-Y carbohydrate specific mAb that is currently tested in a passive immune therapy approach in a clinical phase I trial. For the SPR experiments a BIACORE 3000 analyzer was used. The ligand IGN311 was covalently coupled to the carboxy-methylated dextran matrix of a CM5 research grade chip (BIACORE). In the course of a fully nested experimental design, a four parameter logistic equation was identified as appropriate calibration model ranging from 0.3 μg/mL (lower limit of quantitation, LLOQ) to 200 μg/mL (upper limit of quantitation, ULOQ) using an anti-idiotypic mAb (‘HAHA mimic’) as calibrator. The bias ranged from −2.4% to 5.5% and the intermediate precision expressed as 95% CI revealed values from 5.6% to 8.3%. Specificity was evaluated using six human serum matrices from healthy donors spiked with calibrator at the limit of quantitation (LOQ) with >80% of values being recovered with less than 25% relative error. The qualified assay was applied to monitor potentially induced HAHA reactivity in 11 patients from a clinical phase I trial with passively administered IGN311. Of the 11 patients, one high HAHA responder and several low responders were identified. Protein-G depletion experiments with human serum samples revealed that the observed response is predominantly caused by IgG binding to the ligand. The characteristics of these HAHA responses were all of the so-called ‘Type I’ which is defined by a peak response around day 15 that decreases from this point steadily suggesting that some kind of tolerance is established. Therefore, this type of HAHA response is regarded as non critical for the patient's safety.

Safety, pharmacokinetic and dosimetry evaluation of the proposed thrombus imaging agent 99mTc-DI-DD-3B6/22-80B3 Fab′

(99m)Tc-DI-DD-3B6/22-80B3 (Thromboview, hereafter abbreviated to (99m)Tc-DI-80B3 Fab') is a humanised, radiolabelled monoclonal antibody Fab' fragment with high affinity and specificity for the D-dimer domain of cross-linked fibrin. The purpose of this study was to evaluate the safety, pharmacokinetics and dosimetry of four increasing doses of (99m)Tc-DI-80B3 Fab' in healthy volunteers. Thirty-two healthy volunteers (18-70 years; 16 male, 16 female) received a single intravenous injection of 0.5, 1.0, 2.0 or 4.0 mg of (99m)Tc-DI-80B3 Fab'. Safety outcomes (vital signs, electrocardiography, haematology, biochemistry, adverse events and development of human anti-human antibodies) were assessed up to 30 days post injection. Blood and urine samples were collected up to 48 h post injection. Gamma camera images were acquired at 0.5, 1, 2, 4, 6 and 24 h post injection. Dosimetry was performed using standard MIRD methodology. No adverse events considered to be drug related were observed. Human anti-human antibody was not detectable in any subject during the follow-up period. (99m)Tc-DI-80B3 Fab' had a rapid initial plasma clearance (t (1/2)alpha=1 h). The pharmacokinetic profile of the Fab' fragment was generally linear across the four dose cohorts. By 24 h, 30-35% of the administered radioactivity appeared in the urine. There was marked renal accumulation with time, but no specific uptake was identified within other normal tissues. The effective dose was 9 mSv/750 MBq. (99m)Tc-DI-80B3 Fab' is well tolerated, is rapidly cleared and exhibits clinically acceptable dosimetry-characteristics well suited to a potential thrombus imaging agent.

New Approaches to the Treatment of Inflammatory Disorders Small Molecule inhibitors of p38 MAP Kinase

The therapy of chronic inflammatory diseases like rheumatoid arthritis (RA) and inflammatory bowel disease (IBD) has recently been enriched by the successful launch of the anti-cytokine biologicals Etanercept (tumor necrosis factor (TNF) receptor-p75 Fc fusion protein), Infliximab (chimeric anti-human TNF-alpha monoclonal antibody), Adalimumab (recombinant human anti-human TNF-alpha monoclonal antibody) and Anakinra (recombinant form of human interleukin 1beta (IL-1) receptor antagonist). The success of these novel treatments has impressively demonstrated the clinical benefit that can be gained from therapeutic intervention in cytokine signalling, highlighting the central role of proinflammatory cytokine systems like IL-1alpha and TNF-alpha to be validated targets. However, all of the anti-cytokine biologicals available to date are proteins, and therefore suffering to a varying degree from the general disadvantages associated with protein drugs. Therefore, small molecular, orally active anti-cytokine agents, which target specific pathways of proinflammatory cytokines, would offer an attractive alternative to anti-cytokine biologicals. A number of molecular targets have been identified for the development of such small molecular agents but p38 mitogen-activated protein (MAP) kinase occupies a central role in the regulation of IL-1beta and TNF-alpha signalling network at both the transcriptional and translational level. Since the mid-1990s, an immense number of inhibitors of p38 MAP kinase has been characterised in vitro, and to date several compounds have been advanced into clinical trials. This review will highlight the correlation between effective inhibition of p38 MAP kinase at the molecular target and cellular activity in functional assays of cytokine, particularly TNF-alpha and IL-1beta production. SAR will be discussed regarding activity at the enzyme target, but also with regard to properties required for efficient in vitro and in vivo activity.

Epratuzumab (humanised anti-CD22 antibody) in primary Sjögren's syndrome: an open-label phase I/II study

This open-label, phase I/II study investigated the safety and efficacy of epratuzumab, a humanised anti-CD22 monoclonal antibody, in the treatment of patients with active primary Sjögren's syndrome (pSS). Sixteen Caucasian patients (14 females/2 males, 33–72 years) were to receive 4 infusions of 360 mg/m2 epratuzumab once every 2 weeks, with 6 months of follow-up. A composite endpoint involving the Schirmer-I test, unstimulated whole salivary flow, fatigue, erythrocyte sedimentation rate (ESR), and immunoglobulin G (IgG) was devised to provide a clinically meaningful assessment of response, defined as a ≥20% improvement in at least two of the aforementioned parameters, with ≥20% reduction in ESR and/or IgG considered as a single combined criterion. Fourteen patients received all infusions without significant reactions, 1 patient received 3, and another was discontinued due to a mild acute reaction after receiving a partial infusion. Three patients showed moderately elevated levels of Human anti-human (epratuzumab) antibody not associated with clinical manifestations. B-cell levels had mean reductions of 54% and 39% at 6 and 18 weeks, respectively, but T-cell levels, immunoglobulins, and routine safety laboratory tests did not change significantly. Fifty-three percent achieved a clinical response (at ≥20% improvement level) at 6 weeks, with 53%, 47%, and 67% responding at 10, 18, and 32 weeks, respectively. Approximately 40%–50% responded at the ≥30% level, while 10%–45% responded at the ≥50% level for 10–32 weeks. Additionally, statistically significant improvements were observed in fatigue, and patient and physician global assessments. Further, we determined that pSS patients have a CD22 over-expression in their peripheral B cells, which was downregulated by epratuzumab for at least 12 weeks after the therapy. Thus, epratuzumab appears to be a promising therapy in active pSS, suggesting that further studies be conducted.

Demonstration of specific antibodies against infliximab induced during treatment of a patient with ankylosing spondylitis

Therapeutic proteins, such as infliximab, have revolutionized the treatment of many diseases during the last decade and more than 80 therapeutic proteins are currently approved for clinical use. However, all exogenous proteins have the potential to cause antibody formation. In order to ensure patient safety and the efficacy of therapeutic proteins, careful monitoring of the immunogenicity of therapeutic proteins is therefore necessary not only during preclinical trials, but also during the treatment of patients. Here, we report a clear-cut demonstration of the induction of anti-infliximab antibodies during the treatment of a patient with ankylosing spondylitis (AS). Assessment of anti-infliximab antibodies in sera obtained at various time periods were performed using a highly specific double antigen assay system developed in our laboratory. Immunoreactivity was found to be solely specific for infliximab. Because all sera obtained from the patient were found to be negative for the presence of human anti-mouse antibody (HAMA) and anti-human antibodies. The loss of effect of infliximab, as judged by observing the relapse of signs and symptoms of disease in the patient, seemed to be related with the appearance of antibodies. This study clearly demonstrates that monitoring for the induction of specific antibodies during clinical trials is an important issue for therapeutic proteins.

A Phase I Humanized Anti-CD40 Monoclonal Antibody (SGN-40) in Patients with Multiple Myeloma.

SGN-40, a humanized anti-CD40 monoclonal antibody, is being evaluated in a phase I dose escalation study for patients with relapsed and/or refractory multiple myeloma. This single-arm trial is designed to evaluate safety, pharmacokinetics, immunogenicity, antitumor activity, and the maximum tolerated dose. SGN-40 has demonstrated potent in vitro and in vivo efficacy against cell lines expressing CD40, a member of the tumor necrosis factor receptor family. CD40 is widely expressed on tumors of B-cell origin, including myeloma, non-Hodgkin's lymphoma, Hodgkin's disease, and chronic lymphocytic lymphoma. The original protocol called for cohorts of patients to be treated with four weekly infusions of 0.5, 1.0, 2.0, 4.0, 8.0, or 16.0 mg/kg. Sixteen patients were treated at doses ranging from 0.5 – 4.0 mg/kg/wk for four weeks. Enrollment of new patients was temporarily halted after two of three patients developed severe headaches and aseptic meningitis following the first dose at 4 mg/kg. Grade 1 headaches were seen after the first dose in three of six patients receiving 2 mg/kg, but no patients at lower doses reported headaches. We have determined that this drug-related event is a first-dose effect, and was not seen clinically after second or subsequent infusions of SGN-40. SGN-40 appears to trigger cytokine release, and TNF-alpha levels in the plasma are elevated following the first infusion only. Initial pharmacokinetic data in humans demonstrate that the half-life of SGN-40 depends on the dose given: mean values after the first and third infusions were 0.9 and 1.3 days, respectively, at 0.5 mg/kg; 1.7 and 2.6 days at 1.0 mg/kg; and 2.9 and 4.2 days at 2.0 mg/kg. This is consistent with results in non-human primates, in which the half-life was relatively short at low doses. These data suggest that there is a rapid elimination pathway and/or redistribution volume that has not been saturated at the doses used to date. Although human anti-human antibodies (HAHA) have not yet been measured, the preliminary analysis suggests that if antibodies were formed, they did not significantly affect pharmacokinetics. Even at the low doses tested thus far, there is preliminary evidence for antitumor activity; four of sixteen patients had declining serum and/or urine M-protein during treatment. Of note, these four individuals also demonstrated the most profound B-cell depletion during therapy, an expected consequence of SGN-40 activity. This protocol has been amended to include a drug-loading period that should eliminate first-dose cytokine release syndrome. Dose escalation is ongoing under the revised protocol, and no headaches have been seen in the first cohort at a peak dose of 3 mg/kg. In conclusion, SGN-40 demonstrated an apparent first-dose cytokine release reaction that required a modification in the dosing strategy. Pharmacokinetic data suggest that higher doses are required to saturate the elimination pathway, and preliminary antitumor activity is encouraging.

Initial Safety and Efficacy Results of a Second-Generation Humanized Anti-CD20 Antibody, IMMU-106 (hA20), in Non-Hodgkin's Lymphoma.

Background. Infusion reactions, prolonged infusion times and immunogenicity of the chimeric anti-CD20 antibody, rituximab, may in part be related to its murine component. The humanized anti-CD20 antibody, IMMU-106 (hA20), may offer potential advantages because only the CDRs are of murine origin and the remaining >90% human framework regions are identical to humanized anti-CD22 IgG1 antibody epratuzumab, whose safety and short infusion times have been reported.Methods. An open-label, multicenter, phase I/II, dose escalation study conducted in patients with recurrent B cell lymphoma to establish the safety, tolerance, pharmacokinetics, and immunogenicity of hA20 administered once weekly for 4 doses.Results. Twenty patients (11 M/9 F, 40–81 y.o) with grade 1–2 follicular (n=16) or other CD20+ B-cell lymphomas (mantle cell, small lymphocytic, marginal zone x 2) were enrolled in the dose escalation portion of this study, receiving 120 mg/m2 (n=7), 200 mg/m2 (n=6), 375 mg/m2 (n=4) or 750 mg/m2 (n=3) weekly x 4. These patients had previously received 1-7 prior therapies (median, 2.5), including treatments with one (n=12) or 2–4 (n=6) rituximab-containing regimens (without progression within 6 months). Five patients (25%) had grade 1–2 infusion reactions predominantly with first hA20 infusion. Median infusion times for 375 mg/m2 of hA20 were 3.3 hours for first infusion, 2.0 hours for subsequent infusions, and were generally shorter at lower doses. Standard laboratory values obtained at each infusion were generally observed to be within normal limits, and human anti-human antibody (HAHA) serum evaluations are negative to date. Peripheral blood B-cell depletion occurred after first infusion and persisted for samples obtained up to 12 weeks following fourth infusion with analysis ongoing. Pharmacokinetic results after first and fourth infusions demonstrate a mean antibody serum half-life of 5.3 ± 5.3 and 12.0 ± 8.7 days, respectively. To date, of 15 pts with at least one post-treatment assessments now completed, there are at least 8 objective responses (53%) by Cheson criteria, including 6 patients (40%) with complete responses [CR, CRu] at a median follow-up of 12 weeks. Complete responses have been observed at all dose levels, including 3/7 patients receiving 120 mg/m2/wk.Conclusion. This study demonstrates the safety, tolerability, and preliminary efficacy of this humanized anti-CD20 antibody administered weekly for 4 doses, mostly to patients with follicular lymphomas who relapsed after rituximab-containing regimens. The demonstration of CRs, tolerability, and relatively short infusion times is encouraging. This study is continuing and expanding to assess the durability of responses and the optimal dose for subsequent studies.

Molecular cloning and characterization of markers and cytokines for equid myeloid cells

The myeloid cell system comprises of monocytes, macrophages (MΦ), dendritic cells (DC), Kupffer cells, osteoclasts or microglia and is also known as the mononuclear phagocytic system (MPS). Essential cytokines to differentiate or activate these cells include GM-CSF or IL-4. Important markers for characterization include CD1, CD14, CD68, CD163 and CD206. All these markers, however, were not cloned or further characterized in equids by use of monoclonal antibodies earlier. To overcome this problem with the present study, two approaches were used. First, we cloned equine cytokines and markers, and second we analyzed cross-reactivity of human homologues or anti-human monoclonal antibodies. For cloning of equine cytokines and markers, we used degenerate primers delineated from other species, or equine-specific primers based on previous information in Genbank. Flow cytometry was used to determine the expression of markers on myeloid cells. Cross-reactivity could be shown for anti-human CD14, CD163 and mannose receptor (CD206) mAbs. Surface markers such as CD1 and CD68 that distinguish MΦ and DC were cloned and sequenced. According to blast homology, equine CD1a and CD1b could be identified and distinguished. With the resulting information, dendritic cells and macrophages of horses may be characterized.

Inhibition of human interleukin‐13‐induced respiratory and oesophageal inflammation by anti‐human‐interleukin‐13 antibody (CAT‐354)

Allergic asthma is a complex disorder characterized by local and systemic T helper type 2 -cell responses such as the production of IL-13, a cytokine associated with the induction of airway hyper-responsiveness (AHR), chronic pulmonary eosinophilia, airway mucus overproduction and eosinophilic oesophagitis. Our study aimed to address the therapeutic potential of a human anti-human IL-13 IgG4 monoclonal antibody (CAT-354) in a murine model of respiratory and oesophageal inflammation induced by intratracheal human IL-13. BALB/c mice were treated on days 1 and 3 with CAT-354 (intraperitoneal injection), and human IL-13 was injected intratracheally on days 2 and 4. AHR to methacholine, airway eosinophilia in bronchoalveolar lavage fluid, histologic analysis of goblet cell metaplasia and oesophageal eosinophilia were evaluated. Human IL-13 induced airway eosinophilia and goblet cell metaplasia in mice in a dose-dependent manner. Moreover, intratracheal dosing with 25 microg of human IL-13 was sufficient to induce AHR, goblet cell metaplasia and oesophageal eosinophilia. Pretreatment with CAT-354 significantly reduced AHR, airway eosinophilia and oesophageal eosinophilia. These results demonstrate that anti-human IL-13 (CAT-354) is a potential therapeutic treatment for allergic airway and oesophageal diseases.

Phase I Trial of 131I-huA33 in Patients with Advanced Colorectal Carcinoma

Humanized monoclonal antibody A33 (huA33) targets the A33 antigen which is expressed on 95% of colorectal cancers. A previous study has shown excellent tumor-targeting of iodine-131 labeled huA33 (131I-huA33). Therefore, we did a phase I dose escalation trial of 131I-huA33 radioimmunotherapy. Fifteen patients with pretreated metastatic colorectal carcinoma each received two i.v. doses of 131I-huA33. The first was an outpatient trace-labeled "scout" dose for biodistribution assessment, followed by a second "therapy" dose. Three patients were treated at 20, 30, and 40 mCi/m2 dose levels, and six patients at 50 mCi/m2 to define the maximum tolerated dose. Hematologic toxicity was 131I dose-dependent, with one episode of grade 4 neutropenia and two episodes of grade 3 thrombocytopenia observed at 50 mCi/m2. The maximum tolerated dose was determined to be 40 mCi/m2. There were no acute infusion-related adverse events, and gastrointestinal toxicity was not observed despite uptake of 131I-huA33 in bowel. Seven patients developed pruritus or rash, which was not related to 131I dose. There was excellent tumor-targeting of 131I-huA33 shown in all patients. The serum T1/2beta of 131I-huA33 was (mean +/- SD) 135.2 +/- 46.9 hours. The mean absorbed tumor dose was 6.49 +/- 2.47 Gy/GBq. Four patients developed human anti-human antibodies. At restaging, 4 patients had stable disease, whereas 11 patients had progressive disease. Radioimmunotherapy using 131I-huA33 shows promise in targeting colorectal tumors, and is deliverable at a maximum tolerated dose of 40 mCi/m2. Further studies of 131I-huA33 in combination with chemotherapy are planned.

A Phase I Trial of Humanized Monoclonal Antibody A33 in Patients with Colorectal Carcinoma: Biodistribution, Pharmacokinetics, and Quantitative Tumor Uptake

To determine the in vivo characteristics of huA33, a CDR-grafted humanized antibody against the A33 antigen, we have conducted an open-label, dose escalation, biopsy-based phase I trial of huA33 in patients with colorectal carcinoma. Patients with colorectal carcinoma were infused with [131I]huA33 (400 MBq: 10 mCi) and [125I]huA33 (40 MBq: 1 mCi) 1 week before surgery. There were four huA33 dose levels (0.25, 1.0, 5.0, and 10 mg/m2). Adverse events, pharmacokinetics, biodistribution, tumor biopsies, and immune responses to huA33 were evaluated. There were 12 patients entered into the trial (6 males and 6 females; age range, 39-66 years). No dose-limiting toxicity was observed. The biodistribution of huA33 showed excellent uptake of [131I]huA33 in metastatic colorectal carcinoma. Pharmacokinetic analysis showed no significant difference in terminal half-life (T1/2beta) between dose levels (mean +/- SD, 86.92 +/- 22.12 hours). Modeling of colon uptake of huA33 showed a T1/2 of elimination of 32.4 +/- 8.1 hours. Quantitative tumor uptake ranged from 2.1 x 10(-3) to 11.1 x 10(-3) %ID/g, and tumor/normal tissue and tumor/serum ratios reached as high as 16.3:1 and 4.5:1, respectively. Biosensor analysis detected low-level human anti-human antibody responses in four patients following huA33 infusion. huA33 shows selective and rapid localization to colorectal carcinoma in vivo and penetrates to the center of large necrotic tumors, and colon elimination half-life of huA33 is equivalent to basal colonocyte turnover. The excellent targeting characteristics of this humanized antibody indicate potential for the targeted therapy of metastatic colorectal cancer in future trials.

Phase I and pharmacokinetic study of a subcutaneously administered human-engineered monoclonal antibody ING-1 in patients with advanced adenocarcinomas

2558 Background: ING-1 is a high-affinity, human-engineered monoclonal antibody that recognizes a 40 kD Epithelial Cell Adhesion Molecule (EpCAM) glycoprotein. EpCAM is expressed in high levels on most carcinomas and is an attractive target for immunotherapy. Methods: This was an open-label, multi-dose, phase I, dose-escalating study in patients (pt) with advanced adenocarcinomas to determine the MTD, bioavailability, safety, tolerability, immunogenicity and pharmacokinetics (PK) of weekly subcutaneous (SC) ING-1, administered for 6 weeks. PK samples were drawn during week 1 and 6 predose, at 6 hours and at days 2, 3, 5, 8, 15, 22, 29, 37, 38, 40, and 43. Results: Fourteen pt [lung (1 pt), ovarian (3 pt), colorectal (10 pt)] received a median of 6 (range: 1–9) doses of ING-1 between 0.1 and 2 mg/kg. No week-1 DLT was observed. However, at 1 mg/kg, a 62-year-old man with colon cancer developed grade 3 reversible pancreatitis after the 3rd dose. His plasma ING-1 levels were similar to the other 2 subjects receiving 1 mg/kg. The episode resolved with conservative management. Patients still receiving therapy at 1 and 2 mg/kg were subsequently dose reduced to 0.6 mg/kg. Across all doses, grade 2 or greater drug-related toxicities included nausea (1 pt), diarrhea (4 pt), abdominal pain (4 pt), leg pain (1 pt), pancreatitis (1 pt), and anemia (1 pt). Two patients, with ovarian and colon cancer experienced stable disease of 12 and 6 weeks respectively. Peak ING-1 levels after the first dose increased with dose from 0.122 0.054 ÿg/mL (mean SD, n=4) at 0.1 mg/kg to 6.77 1.55 ÿg/mL (n=3) at 1 mg/kg. Only one subject received 2 mg/kg ING-1, with a peak level of 3.57 ÿg/mL. Peak ING-1 levels after the last dose were higher than after the first dose, suggesting accumulation of ING-1. Low (< 90 neq/mL) human anti-human antibody (HAHA) responses were noted in 3 of the 13 (23%) subjects assessed and were directed towards a variable region of ING-1. Conclusions: ING-1 administered weekly SC had modest side effects with little observed clinical benefit in this refractory patient population. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration XOMA US [LLC]

Safety and efficacy of panitumumab monotherapy in patients with metastatic colorectal cancer (mCRC)

3520 Background: Panitumumab (formerly ABX-EGF) is a fully human monoclonal antibody that binds with high affinity to the epidermal growth factor receptor (EGFr). This ongoing phase 2 study is evaluating the safety and efficacy of panitumumab monotherapy in patients (pts) with mCRC who have failed standard chemotherapy. Here we present mature unaudited data from the ongoing study. Methods: Pts with mCRC who failed therapy with a fluoropyrimidine (± leucovorin) and either irinotecan or oxaliplatin, or both, were eligible for this study. Cohort A included pts with EGFr staining of 2+ or 3+ in ≥ 10% tumor cells; cohort B included pts with EGFr staining of the sum of 1+, 2+ and 3+ in ≥ 10% of tumor cells, but with the sum of 2+ and 3+ in < 10% of tumor cells. Panitumumab was given IV at 2.5 mg/kg once weekly in 8-wk cycles. Pts continued receiving treatment until disease progression or unacceptable toxicity occurred. Endpoints included tumor response (RECIST), time to disease progression, survival, and safety. Results: Enrollment is complete, with treatment ongoing. In total, 148 pts were treated (82 men/66 women; ECOG status of 1 [n = 111] or 0 [n = 37]; mean age 59 yrs [range 21 - 88 yrs]). Efficacy results are shown in the table. The 4 most frequently reported grade (gr) 3 or 4 treatment-related adverse events (AEs) were rash NOS (5 pts), fatigue (4 pts), vomiting NOS (2 pts), nausea (1 pt), and pruritus (1 pt). Skin toxicity-related AEs were reported for 141 pts (95%; 5% gr 3 and no gr 4). One infusion-related gr 3 AE, which did not require dose modification, was reported; no other infusion-related AE has been reported to date. No human anti-human antibodies were observed in 145 pts tested. Conclusions: These mature data confirm previously reported safety and response findings (Hecht et al, 2004) and provide encouraging survival data in pts with mCRC who have failed multiple lines of standard chemotherapy. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Amgen Amgen, Genentech, Pfizer, Sanofi Amgen Amgen, Bristol-Myers Squibb, Genentech, Novartis, Pfizer, Roche Amgen, Eli Lilly, Pfizer, Roche Amgen

A humanizedaAnti-CD40 monoclonal antibody (SGN-40) demonstrates antitumor activity in non-Hodgkin’s lymphoma: Initiation of a phase I clinical trial

6572 Background: CD40, a member of the Tumor Necrosis Factor (TNF) receptor family, is expressed on the cell surface of normal B lymphocytes, their progenitors, and B cell malignancies, including both indolent and aggressive forms of non-Hodgkin’s lymphoma (NHL). Because this represents an attractive target for immunotherapy, a humanized monoclonal anti-CD40 antibody (SGN-40) has been developed and tested in preclinical models. Methods: SGN-40-dependent proliferation and cell killing were tested in vitro using normal B cells and malignant lymphoma cell lines. Antibody-dependent cell-mediated cytotoxicity (ADCC) was assessed by adding peripheral blood mononuclear cells or purified NK cells to malignant cell lines in the presence of SGN-40. In vivo activity of SGN-40 was determined by xenograft models in SCID mice. Results: Although SGN-40 induces proliferation of normal B cells when crosslinked and exposed to exogenous IL-4, there was dose-dependent B cell depletion and no evidence of activation in non-human primates. Furthermore, malignant cell lines undergo significant antibody-induced cell death (AICD) via apoptosis and ADCC in vitro. SGN-40 is highly active in xenotransplant models, in which Ramos and IM9 cell lines are injected into SCID mice. Mice receiving control IgG died by day 35 whereas those receiving SGN-40 4 mg/kg x 5 doses survived until day 90. Furthermore, these effects are seen in the SCID-beige mice, which lack significant NK cell activity (i.e. ADCC). SGN-40 has in vivo activity in transplanted malignant cell lines that are markedly resistant to rituximab and shows synergy when used together with anti-CD20 therapy. Conclusions: Based on these encouraging data, as well as adequate safety data from non-human primates and an ongoing trial in multiple myeloma, we have initiated a phase I dose escalation trial of SGN-40 in NHL. Anti-CD40 mAb will be given for four consecutive weeks at 2–16 mg/kg/week. Pharmacokinetic data, development of human anti-human antibodies, toxicity, and clinical responses will be evaluated carefully in this heavily pre-treated population of patients. This study is currently open in four sites and patient accrual has begun. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Seattle Genetics Seattle Genetics Seattle Genetics

Phase I and pharmacokinetic study of HGS-ETR2, a human monoclonal antibody to TRAIL R2, in patients with advanced solid malignancies

3055 Background: HGS-ETR2 is a fully-human high affinity monoclonal antibody specific and agonistic to the Tumor Necrosis Apoptosis Inducing Ligand (TRAIL) Receptor 2. HGS-ETR2 mediates apoptosis by binding to TRAIL-R2, leading to activation of the extrinsic apoptosis pathway. Human tumor xenograft models show tumor regression in response to HGS-ETR2 at doses of 2.5 mg/kg or lower. Methods: Patients with advanced solid tumors were treated with HGS-ETR2 IV once every 21 days. Results: Currently 22 patients have received 73 courses of HGS-ETR2 over 5 dose levels ranging from 0.1 to 10 mg/kg. The majority (20/22) received at least 2 courses (range 1 - 13). One patient experienced an asymptomatic grade 3 elevation of serum amylase at 1 mg/kg detected at course 1 day 15 with a peak amylase of 423 u/L (3.4 x ULN) while receiving concomitant ciprofloxacin; no other patients have experienced dose-limiting toxicity. One subject with hepatocellular carcinoma and extensive hepatic metastases experienced grade 3 transient transaminitis at 3 mg/kg during Cycle 5 which resolved by Cycle 6, and went on to receive a further course with no enzyme changes. To date, stable disease (= 2 cycles) has been observed in seven subjects (range 2–13). HGS-ETR2 pharmacokinetics are linear across a 100-fold dose range, from 0.1 to 10 mg/kg, and at the 10 mg/kg dose are characterized by a mean (SD) t1/2,z of 15 (4) days, CL of 4.79 (2.30) mL/day/kg, and V1 of 51 (5) mL/kg, which is slightly larger than the plasma volume. The 1.7-fold larger Vss of 87 (7) mL/kg indicates that HGS-ETR2 distributes outside the plasma volume. Human anti-human antibody formation has not been detected. Conclusions: HGS-ETR2, a specific TRAIL R2 targeting agent, can be safely administered IV every 3 weeks at doses that reach plasma concentrations associated with activity in preclinical models. Further evaluation in Phase II trials is warranted. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Human Genome Sciences Human Genome Sciences Human Genome Sciences Human Genome Sciences

Updated results from a dose and schedule study of Panitumumab (ABX-EGF) monotherapy, in patients with advanced solid malignancies

3059 Background: Panitumumab is a fully human monoclonal antibody to the epidermal growth factor receptor (EGFr). This open-label, multiple-infusion, dose-escalation trial evaluated the safety, pharmacokinetics (PK), and antitumor activity of panitumumab in advanced solid tumor patients. Methods: Sequential cohorts of patients were enrolled to receive four infusions at different dose levels and schedules of panitumumab monotherapy ranging from 0.01 to 5.0 mg/kg once per week (QW), 6.0 mg/kg once every 2 weeks (Q2W) or 9.0 mg/kg once every 3 weeks (Q3W) administered IV over one hour without premedication. Patients were prescreened for EGFr expression and had to have at least 1+ expression in ≥10% of tumor cells. Stable or responding patients were eligible for extended panitumumab treatment on a separate protocol for six additional months or until disease progression. Patients had to have acceptable organ function, and may have received prior systemic anti-tumor therapy. Preliminary results are presented below. Results: Ninety-six patients (72 [75%] men) were treated with panitumumab. The mean age was 60.4 yrs (range 32–79). Tumor types included 39 colorectal (CRC), 14 lung, 3 pancreatic, 21 prostate, 15 renal, 3 esophageal/gastrosophageal, and 1 anal cancer. The incidence of skin-related toxicities was dose dependent and plateaued at >2.0 mg/kg QW. Grade 3 or 4 related adverse events were noted in 10% of patients with grade 3 skin-related toxicities being the most frequent (7% of patients). No MTD was reached. No human anti-human antibody formation or infusion related reactions were observed. PK exposure was similar between 2.5 mg/kg QW, 6 mg/kg Q2W and 9 mg/kg Q3W. By investigator assessment, 5 confirmed partial responses (WHO) (12.8% RR, 5/39 CRC patients), 1 minor PSA response, and 18 patients with stable disease were observed. Conclusions: Panitumumab is generally well tolerated. The exposure and tolerability profile is comparable between QW, Q2W, and Q3W schedules. Panitumumab has single agent anti-tumor activity in solid tumors, most notably in subjects with advanced CRC. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Abgenix, Amgen