Human IgM monoclonal antibody 16.88: pharmacokinetics and immunogenicity in colorectal cancer patients.

Twenty colorectal cancer patients were given an intravenous injection of human IgM monoclonal antibody (MAb) 16.88 (8 mg) conjugated to 131I for tumor localization. After a 2-week interval, a second injection with 200, 500, or 1000 mg of unlabeled antibody added was given to groups of five patients each. at the end of the 2-hour infusion, 66% of the radioactivity remained in the circulation. Blood clearance of the 131I-labeled MAb 16.88 was biphasic with a mean half-life (T1/2 alpha) of 12 hours and T1/2 beta of 45 hours. Clearance rate was 0.09 L/hour. More than 90% of the 131I in serum was protein bound, with an immunoreactive fraction of 80% in the first 48 hours. Size exclusion chromatography indicated no degradation products other than 131I in serum and urine. The urinary excretion rate of 131I increased to 1.5% of the dose per hour at 24 hours, with 50% of the dose excreted in 34 hours. The pharmacokinetic profile of 131I-labeled MAb 16.88 was neither influenced by the total protein dose of antibody administered nor affected by specific uptake in tumor tissue in individual patients, as determined on early immunoscintigrams. The larger antibody doses showed a slightly slower excretion of 131I. The assays applied to determine immunogenicity were enzyme-linked immunosorbent assay, radioimmunoassay, and the dot-blot assay. They had sensitivities ranging from 5 ng/mL to 0.5 micrograms/mL for goat or rabbit antihuman IgM. The assays did not reveal antihuman antibody responses.

Physiological disposition of 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine in humans.

[2-14C]-2,2'-Anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine ([14C]AAFC) was given to 7 patients i.v. and to 3 patients p.o. at doses of 2 or 20 mg/kg. After i.v. administration of [14C]AAFC, 20 mg/kg, maximum plasma levels of up to 42.5 mug [14C]AAFC equivalents per ml of plasma occurred. A rapid exponential decrease of the radioactivity resulted in an initial half-line of 0.5 to 1.5 hr for the first part and a half-line of 8 to 24 hr for the second part of the curve. Most of the radioactivity was unchanged starting material. In plasma, 1-beta-D-arabinofuranosyl-5-fluorocytosine was found for only a short time and at low levels after i.v. injection. Its deamination product, 1-beta-D-arabinofuranosyl-5-fluorouracil (AFU), too, showed up in minor quantities. A small amount of 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorouracil was also detected. Administration p.o. of the 14C-labeled drug (2 mg/kg) resulted in the slow appearance of radioactivity in plasma. It peaked at 6 to 18 hr and slowly disappeared with a half-life of 12 to 18 hr. In a fasting patient, [14C]AAFC, 20 mg/kg, administered p.o. resulted in its rapid absorption into the bloodstream and in elevated levels in plasma for 48 hr. The unchanged drug and AFU were the predominant substances identified in plasms. Radioactivity after i.v. injection was found primarily in urine; only small amounts were recovered in expired air (to 2.4%) and traces were found in feces. The predominant urinary excretions product was the unchanged drug (average, 79%). The rest was AFU (average, 12.4%), 1-beta-D-arabinofuranosyl-5-fluorocytosine (average, 3.9%), and 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorouracil (average, 1.9%). After p.o. administration of the labeled drug, the calculated absorption was 32%. Urine contained about 50% unchanged drug and 40% AFU; the remainder was composed of 1-beta-D-arabinofuranosyl-5-fluorocytosine and the deaminated anhydro compound, 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorouracil. The rate of excretion in the urine was slow. In general after both i.v. and p.o. administration, spinal fluid contained considerably less radioactivity than plasma at shor intervals after the administration. At longer intervals after i.v. and p.o. administration, spinal fluid contained comparable or even considerably higher levels of radioactivity when compared to the levels in plasma. Autopsies performed 6 to 25 days after i.v. or p.o. drug administration revealed that radioactivity remained in kidney, spleen, small intestine, liver, and lung.

Antiidiotype antibodies in cancer patients receiving monoclonal antibody to carcinoembryonic antigen.

The initial 10 patients of a Phase I clinical trial involving multiple injections of murine monoclonal anti-carcinoembryonic antigen (CEA) antibody, NP-2, were studied for the presence in their sera of antiidiotypic antibody. Most patients had advanced gastrointestinal adenocarcinoma and received 1 mg/m2 monoclonal antibody three times weekly, or once a week, resulting in five to 13 injections over 12 to 240 days. Antiidiotype antibody was detected with a blocking radioimmunoassay using [125I]NP-2-F(ab')2 binding to CEA-coated microwells and [125I]NP-4-F(ab')2 as a control antibody. Five out of 10 patients demonstrated 65-96% inhibition of NP-2 binding at 1/20 dilution of serum compared to NP-2 binding in the presence of pretreatment sera. The inhibitory activity was preserved after adsorption over a polyclonal mouse IgG immunoadsorbent whereas exposure to a NP-2 affinity column completely depleted the activity. Specificity testing, including the blocking effect of patient sera on the control antibody NP-4, and interference by the possible presence of circulating NP-2, circulating CEA, and human anti-CEA activity, confirmed that the inhibition observed was specific for NP-2 and was caused by an agent with CEA-like characteristics. Longitudinal studies demonstrated that elevated titers of antiidiotypic antibody appeared later in the course of immunization than did antibody against mouse immunoglobulin. These studies indicate that patients can be sensitized to the idiotype (anti-combining site and/or combining site-related) of monoclonal antibodies to CEA following multiple infusions.

Human immune response to anti-carcinoembryonic antigen murine monoclonal antibodies.

We previously demonstrated that patients with carcinoembryonic antigen [CEA]-producing neoplastic tumors, treated with murine monoclonal antibody to CEA, produced antibodies directed against the constant regions [human anti-mouse antibody (HAMA)] and the idiotypes [anti-Id] of these murine immunoglobulins. In this study, we describe a method for analyzing the presence of such antibodies in the sera of these patients. The HAMAs were measured by enzyme immunoassay and removed by immunoadsorption on Affi-Gel mouse IgG. The unabsorbed fraction contained the anti-Id antibodies; their presence was demonstrated by binding to the CEA monoclonal antibody (Ab1). The specificity of the binding was assessed by preincubating the sera with Ab1 and measuring the residual nonspecific binding. When specific binding was detected, the anti-Id antibodies were isolated by adsorption and elution on Affi-Gel Ab1. The anti-Id antibodies were fixed on enzyme immunoassay plates and incubated with a panel of mouse anti-human immunoglobulin to determine their isotypes. In a first series of 24 patients, HAMAs were found in 20 cases and anti-Id antibodies in 19 cases. The isolation of a specific IgG to Ab1 was achieved in 2 cases. In an ongoing series, the HAMA and anti-Id antibodies were detected in all five patients given injections of another monoclonal antibody to CEA. In two patients an IgG1 kappa anti-Id was isolated from the serum. The potential therapeutic effect of these antibodies is under investigation.

Tumour localisation with 131I-labelled human IgM monoclonal antibody 16.88 in advanced colorectal cancer patients.

Human IgM monoclonal antibody 16.88 recognised an intracellular antigen strongly expressed in colorectal cancer tissue in 51% of our patients. Tumour localisation was carried out with 185 MBq 131I-16.88 (8 mg) in 20 of these patients with advanced disease. In 16 patients (80%) immunoscintigraphy was positive in at least one organ site with disease. Of all sites, 55% could be visualized. In general, lesions less than 3 cm could not be detected. Sequential immunoscintigrams of liver metastases showed variable patterns. Initial "cold" lesions corresponded to liver metastases with poor blood supply as indicated by 99mTc-sulphur-colloid and 99mTc-HMPAO scintigraphy, respectively. The mean (S.D.) biological half-life (whole body clearance of radioactivity) was 37.6 (5.0) h. A second infusion of 131I-16.88 with the addition of high doses of unlabelled 16.88 could be done safely, but did not result in better visualisation of tumour lesions or affect radioactivity clearance from the body.

Radioimmunolymphoscintigraphy in the preoperative staging of primary breast cancer.

Thirty-one primary breast cancer patients were evaluated by radioimmunolymphoscintigraphy (RILS) and ex vivo scintigraphy (EVS) following subcutaneous injection of human monoclonal antibody In-111-LiLo-16.88. Lymph nodes (370) were assessed by EVS, pathology and immunohistochemistry. The positive predictive value (EVS) for antigen positive nodes, metastatic and hyperplastic, was 90% in stages O-IIB, and the sensitivity and specificity for all stages were 60% and 80% respectively. Four EVS positive nodes with follicular hyperplasia contained micrometastases. RILS and EVS correlate well by the Spearman Rank test (R=0.87). These results suggest RILS may be clinically useful and selectively limit the extent of the surgical procedure.

Distribution and kinetics of 131I-labeled human IgM monoclonal antibody 16.88 in patients with advanced colorectal cancer.

Sequential immunoscintigrams were used to describe the relative distribution and kinetics of 8 mg 131I-labeled human IgM monoclonal antibody 16.88 in 20 patients with colorectal cancer. The results show that the initial activity was higher and the clearance rate was faster (P < 0.05) from the left ventricle and liver than from most organs. In bone marrow the reverse was observed (P < 0.05). The biological half-life of 131I(-16.88) in tumor tissue (range 35.4-47.5 h) was longer (P < 0.01) than that in normal tissue (30.2-41.9 h). The image contrast ratio between liver metastases and background increased from 0.8 to 1.3 and for lesions outside the liver from 1.1 to 1.6. The estimated effective dose equivalent was 0.12 mSv/MBq. A second infusion 2 weeks after the first with the addition of unlabeled 16.88 up to 1000 mg for improvement of tumor tissue uptake was not of clinical relevance.

Comparison of non-invasive approaches to red marrow dosimetry for radiolabelled monoclonal antibodies.

Red marrow is usually the dose-limiting organ during radioimmunotherapy. Several non-invasive approaches to calculate the red marrow dose have been proposed. We compared four approaches to analyse the differences in calculated red marrow doses. The data were obtained from immunoscintigraphy of two antibodies with different red marrow kinetics [iodine-131-16.88 IgM and indium-111-OV-TL-3 F(ab')2]. The approaches are based on, respectively, homogeneously distributed activity in the body, a red marrow-blood activity concentration ratio of 0.3, scintigraphic quantification, and a combination of the second and third approaches. This fourth approach may be more adequate because of its independence from the chosen antibody. In addition, the influence of activity accumulation in liver, kidneys or cancellous bone on red marrow dose was studied. The calculated red marrow dose varied between 0.14 and 0.42 mGy/MBq for 111In-OV-TL-3 and between 0.13 and 0.68 mGy/MBq for 131I-16.88. If the radiopharmaceutical shows high affinity for cancellous bone or another organ situated near the red marrow, the activity in these organs must be included in dose calculations. This study shows a large variation in calculated red marrow dose and selection of the definitive non-invasive approach awaits validation.

The Muir-Torre syndrome: a disease of sebaceous and colonic neoplasms.

The Muir-Torre syndrome of sebaceous neoplasms of the skin, with or without keratoacanthomas, and multiple low-grade visceral malignancies with prolonged survival is a rare disorder. Colonic polyps are frequently present, and the syndrome appears to be familial. We report 2 unrelated patients with the Muir-Torre syndrome. Each case exhibited sebaceous adenomas. Gastrointestinal findings included colonic adenocarcinomas and a tubulovillous adenoma. Although an unusual disease, the Muir-Torre syndrome requires recognition because these patients are at risk for multiple primary malignancies and may have family members also at risk.

A new fiducial alignment system to overlay abdominal computed tomography or magnetic resonance anatomical images with radiolabeled antibody single-photon emission computed tomographic scans.

BACKGROUND: The use of computed tomography (CT) or magnetic resonance (MR) to overlay or register uptake patterns displayed by single-photon emission computed tomography (SPECT) with specific underlying anatomy has the potential to improve image interpretation and decrease diagnostic reading errors. The authors have developed a method that will allow the selection of a region of interest on MR or CT images that correlates with SPECT antibody images from the same patient. This method was validated first in phantom studies and subsequently was used on three patients with suspected colorectal carcinoma. METHODS: Two patients were injected with the technetium-99m-labeled 88BV59 immunoglobulin G human antibody, and the third patient was injected with the iodine-131-labeled 16.88 immunoglobulin M human antibody. CT or MR scans were obtained before antibody infusion, and subsequent SPECT scans were obtained on the first or fourth day after infusion. A customized body cast with landmarks was used for each patient during the CT, MR, and SPECT scans to match slice positions for all scanning modalities. Corresponding fiducial landmarks were identified on axial images. A computer graphics program was written to match and overlay corresponding landmarks for each imaging modality. The image registration accuracy was measured by comparing fiducial marker separations (center to center) on the registered scans. This separation uncertainty was 1-2 mm for CT-MR and 3-4 mm for CT-SPECT phantom studies. RESULTS: For patient studies, the fiducial alignment uncertainty was 3-4 mm for axial CT-SPECT and MR-SPECT images, and 6-8 mm for sagittal CT-SPECT and MR-SPECT images. The accuracy of the anatomic alignment of the patient and image registration system was +/- 1 cm in the medial-lateral axis and +/- 2 cm in the cranial-caudal direction. CONCLUSIONS: This type of image analysis may resolve uncertainties with the anatomic correlation of SPECT images that otherwise may be regarded as questionable when SPECT is used alone for radioimmunodiagnosis.

Tumor activity confirmation and isodose curve display for patients receiving iodine-131-labeled 16.88 human monoclonal antibody.

A study was performed to correlate activity quantitation derived from external imaging with surgical tumor specimens in patients who received radiolabeled monoclonal antibody. Patients were given I-131 labeled 16.88 human antibody and scanned 3-5 times by planar and/or single photon emission computed tomography imaging methods to acquire time-dependent activity data in tumor and normal tissues. A method also was developed to assess the heterogeneous activity distributions in tumor samples. Postsurgical tumor and normal tissue samples were subdivided into volume elements (voxels) of 0.5 cm x 0.5 cm x 0.05 cm thick, which were used to verify the activity quantitation computed by the conjugate view method and to appraise the heterogeneity of radiolabeled antibody uptake. Through the use of the measured voxel activities, along with the time-dependent activity curves available for the entire tumor specimen derived from imaging, the cumulated activity and absorbed dose for each voxel were uniquely determined. The calculated total absorbed dose values were color-coded as isodose curves and overlaid on a correlated computed tomographic image. In two patients, activity quantitation derived from external imaging correlated with surgical tumor resection specimens within +/- 11%. The tumor-absorbed dose heterogeneity ratio was found to be as high as 10:1, with an average tumor to whole body absorbed dose ratio of 4:1. The mapping of activity with a histologic overlay showed a good correlation among activity uptake, the presence of tumor, and antigen expression on a microscopic scale. The resultant isodose curves overlaid on correlative computed tomographic scans represent the first images obtained with actual radiolabeled antibody biodistribution data in patients.

A phase I randomized study of subcutaneous adjuvant IL-2 in combination with an autologous tumor vaccine in patients with advanced renal cell carcinoma.

We performed a prospective, randomized study to determine whether subcutaneous administration of interleukin-2 (IL-2) in combination with an autologous renal cell vaccine is feasible and can potentiate antitumor immunity. Seventeen patients with metastatic renal cell carcinoma underwent surgical resection with preparation of an autologous tumor cell vaccine. Patients were vaccinated intradermally twice at weakly intervals with 10(7) irradiated tumor cells plus bacillus Calmette-Guérin, and once with 10(7) tumor cells alone. Patients were randomized to one of three groups: no adjuvant IL-2, low-dose IL-2 (1.2 x 10(6) IU/m2), or high-dose IL-2 (1.2 x 10(7) IU/m2). IL-2 was administered subcutaneously on the day of vaccination and the subsequent 4 days. Immune response was monitored by delayed-type hypersensitivity (DTH) response to tumor cells as compared with normal autologous renal cells. Sixteen of 17 patients received vaccine therapy. Four patients developed cellular immunity specific for autologous tumor cells as measured by DTH responses; two had received no IL-2 and two had received high-dose IL-2. There were two partial responses (PR) noted, both in patients who received high-dose IL-2. One responding patient was DTH(+) and one was negative. A third patient who was DTH(+) after vaccination with no IL-2 had a dramatic PR after receiving IL-2 subcutaneously in a subsequent protocol. Prospective testing of response to recall antigens indicated that only 5 of 12 tested patients were positive, including both clinical responders. These data suggest that subcutaneously administered adjuvant IL-2 does not dramatically augment the immunologic response to autologous renal cell vaccines as determined by the development of tumor-specific DTH response.