Anti-Gal titers in healthy adults and inflammatory bowel disease patients.

INTRODUCTION: ALPHA-GAL is a glycoconjugate present on cell membranes of mammals and bacteria but not humans who display anti-Gal antibodies (AB) in high titers provoked by the commensal gut flora. In the present study, we sought to determine the longitudinal course of alpha-Gal specific AB titers of all isotypes over 8 weeks among healthy adult subjects. Furthermore, we hypothesized that inflammatory bowel disease (IBD) patients display increased anti-Gal titers. MATERIALS AND METHODS: We drew serum from healthy probands (n=20) weekly for 8 weeks and obtained plasma samples of from patients suffering from Crohn's disease (n=20) and ulcerative colitis (n=20). We measured anti-Gal ABs of all isotypes and total immunoglobulin (Ig) content using an enzyme-linked immunosorbent assay technique. For statistical evaluation of the longitudinal titers, we calculated confidence intervals for the slopes of a random intercept model, comparing variances between and within the probands. For group comparisons, we performed paired student t-tests and Pearson correlations. RESULTS: Alpha-Gal specific IgG, IgM, IgD, and IgA titers remained unvaried within a narrow range upon longitudinal observation. Most probands did not display alpha-Gal specific IgE ABs. Crohn's disease patients showed highly increased alpha-Gal-specific IgA titers compared with control subjects (P<.01). CONCLUSION: Apart from IgE, alpha-Gal-specific ABs of all isotypes remained constant over longer time periods in healthy subjects. Thus, significant titer changes actually represent increased antigen exposure and a specific anti-alpha-Gal response. Crohn's disease patients display increased anti-Gal IgA titers compared with healthy controls, which reflects a chronically impaired mucosal gut barrier in this patient cohort.

Phase I trial of the anti-Lewis Y drug immunoconjugate BR96-doxorubicin in patients with lewis Y-expressing epithelial tumors.

PURPOSE: We conducted a phase I clinical trial of BR96-Doxorubicin (BR96-Dox), a chimeric anti-Lewis Y (Le(Y)) monoclonal antibody conjugated to doxorubicin, in patients whose tumors expressed the Le(Y) antigen. The study aimed to determine the toxicity, maximum-tolerated dose, pharmacokinetics, and immunogenicity of BR96-Dox. PATIENTS AND METHODS: This was a phase I dose escalation study. BR96-Dox was initially administered alone as a 2-hour infusion every 3 weeks. The occurrence of gastrointestinal (GI) toxicity necessitated the administration of BR96-Dox as a continuous infusion over 24 hours and use of antiemetics and antigastritis premedication. Patients experiencing severe GI toxicity underwent GI endoscopy. All patients underwent restaging after two cycles. RESULTS: A total of 66 patients predominantly with metastatic colon and breast cancer were enrolled onto the study. The most common side effects were GI toxicity, fever, and elevation of pancreatic lipase. At higher doses, BR96-Dox was associated with nausea, vomiting, and endoscopically documented exudative gastritis of the upper GI tract, which was dose-limiting at a maximum dose of 875 mg/m(2) (doxorubicin equivalent, 25 mg/m(2)) administered every 3 weeks. Toxicity was reversible and generally of short duration. Premedication with the antiemetic Kytril (granisetron hydrochloride; SmithKline Beecham, Philadelphia, PA), the antacid omeprazole, and dexamethasone was most effective in ameliorating GI toxicity. A dose of 700 mg/m(2) BR96-Dox (doxorubicin equivalent, 19 mg/m(2)) every 3 weeks was determined to be the optimal phase II dose when administered with antiemetic and antigastritis prophylaxis. BR96-Dox deposition on tumor tissue was documented immunohistochemically and by confocal microscopy. At the 550-mg/m(2) dose, the half-life (mean +/- SD) of BR96 and doxorubicin was 300 +/- 95 hours and 43 +/- 4 hours, respectively. BR96-Dox elicited a weak immune response in 37% of patients. Objective clinical responses were seen in two patients. CONCLUSION: BR96-Dox provides a unique strategy to deliver doxorubicin to Le(Y)-expressing tumor and was well tolerated at doses of 700 mg/m(2) every 3 weeks. BR96-Dox was not associated with the typical side-effect profile of native doxorubicin and can potentially deliver high doses of doxorubicin to antigen-expressing tumors. A phase II study in doxorubicin-sensitive tumors is warranted.

A phase II study of BTI-322, a monoclonal anti-CD2 antibody, for treatment of steroid-resistant acute graft-versus-host disease.

BTI-322, a rat monoclonal IgG2b directed against the CD2 antigen on T cells and natural killer (NK) cells, blocks primary and memory alloantigen proliferative responses in vitro. We have evaluated the pharmacokinetics and safety of BTI-322 during treatment of 20 transplant recipients with steroid-refractory acute graft-versus-host disease (GVHD). Treatment consisted of BTI-322 by intravenous (IV) bolus or 30-minute infusion at approximately 0.1 mg/kg/d for 10 days in addition to continuing high-dose steroids and tacrolimus or cyclosporine. Pharmacokinetic sampling was performed in 10 patients; the t1/2 +/- SE was 9.1 +/- 1.3 hours, the Cmax was 2,549 +/- 291 ng/mL, the Vd was 3.97 +/- 0.95 L, and the Vd/kg was 0. 05 +/- 0.01 L/kg. Ten patients experienced transient dyspnea sometimes accompanied by nausea, vomiting, diarrhea, and tachycardia shortly after the initial bolus dose of drug, but serious drug-related adverse events were not seen during the remainder of the infusions. At the end of treatment (day 11), there were six patients with complete responses and five with a reduction in grade of GVHD for a total response rate of 55% (95% confidence interval [CI], 32% to 77%). Antibodies targeting CD2 may be active in the treatment of acute GVHD, and evaluation of a humanized form of BTI-322 is warranted.

Effect of recombinant alpha-interferon on pharmacokinetics, biodistribution, toxicity, and efficacy of 131I-labeled monoclonal antibody CC49 in breast cancer: a phase II trial.

Preclinical studies have demonstrated that recombinant IFN-alpha (rIFN-alpha) can enhance the tumor associated glycoprotein 72 (TAG-72) on tumors. To determine whether rIFN-alpha could enhance TAG-72 expression in vivo in patients, 15 women with breast cancer were randomized to receive daily injections of rIFN-alpha (3 x 10(6) units/m2 for 14 days) beginning on day 1 (group 1 = 7 patients) or on day 6 (group 2 = 8 patients). On day 3, all patients received a 10-20-mCi tracer dose of 131I-CC49, a high-affinity murine monoclonal antibody reactive against TAG-72, followed by a therapy dose of 60-75 mCi/m2 of 131I-CC49 on day 6. Whole body and single-photon emission computed tomography scans along with whole blood pharmacokinetics were performed following tracer and treatment phases. Hematological toxicity was considerable; reversible grade 3-4 neutropenia and thrombocytopenia was observed in 12 of 15 patients. Twelve of 14 patients tested developed human antimouse antibodies 3-6 weeks after treatment. For group 1 patients, whole blood residence time increased significantly between that predicted from the tracer doses and therapy doses (42.6 +/- 4.7 versus 51.5 +/- 4.8 h, respectively; P < 0.01). The calculated radiation absorbed dose to red marrow from therapy compared to tracer activity was also significantly higher for this group (1.25 +/- 0.35 versus 1. 07 +/- 0.26 cGy/mCi; P < 0.05). Treatment with rIFN-alpha was found to enhance TAG-72 expression in tumors from patients receiving rIFN-alpha (group 1) by 46 +/- 19% (P < 0.05) compared to only 1.3 +/- 0.95% in patients not initially receiving IFN (group 2). The uptake of CC49 in tumors was also significantly increased in rIFN-alpha-treated patients. One partial and two minor tumor responses were seen. In summary, rIFN-alpha treatment altered the pharmacokinetics and tumor uptake of 131I-CC49 in patients at the expense of increased toxicity.

Enhanced TAG-72 expression and tumor uptake of radiolabeled monoclonal antibody CC49 in metastatic breast cancer patients following alpha-interferon treatment.

The IFNs, alpha and gamma, have been shown to enhance the tumor-associated glycoprotein (TAG-72) on adenocarcinoma cells in vitro and in mice with human breast cancer xenografts, resulting in improved targeting of monoclonal antibody CC49. To determine the effect of IFN-alpha on biodistribution and tumor uptake of 131I-labeled CC49, patients with metastatic breast cancer were randomized to either receive or not receive IFN-alpha (3 million units daily for 14 days) by s.c. injection. Three days after beginning IFN-alpha, all patients received 10-20 mCi of 131I-CC49 (specific activity, 16.7 mCi/mg) i.v. Total-body Anger camera scans, along with total-body blood and plasma pharmacokinetics, were performed. Tumor biopsies were taken in all patients before and 48 h after IFN-alpha treatment. There were no significant differences in number of metastases imaged or whole-body, blood and plasma pharmacokinetics between IFN-alpha-treated and untreated patients. Quantitative immunohistochemistry on biopsy specimens from IFN-alpha-treated patients demonstrated a significant increase in mean +/- SEM TAG-72 expression (45.7 +/- 19.4%) compared to patients that were not given IFN-alpha (1.3 +/- 0.95%; P < 0.05). Although slight increases in the percent injected dose of 131I-CC49 in tumor occurred after IFN-alpha-treatment, the changes were not significant at the P < 0.05 level. These data suggest that IFN-alpha may be useful in enhancing TAG-72 antigen expression in vivo in humans, despite modest improvement in tumor uptake of CC49, possibly because of limited tumor access or other unknown factors.