Antibody-guided irradiation of hepatic metastases using intrahepatically administered radiolabelled anti-CEA antibodies with simultaneous and reversible hepatic blood flow stasis using biodegradable starch microspheres

Radiolocalisation of an anti-CEA Monoclonal Antibody (FO23C5) and its Fragments in a Colon Carcinoma Xenograft Model

A new monoclonal antibody designated FO23C5 against a protein component of carcinoembryonic antigen (CEA) has been developed. A xenograft system of human colon cancer was used to compare the intact monoclonal IgG with its fragments ((Fab’)2 and Fab) and with an established anti-CEA antibody (MAb35) and the antibody AUA1 raised against the colon carcinoma cell line. We demonstrate that FO23C5 compares well with the existing anti-CEA antibody and with AUA1, and that F(ab’)2 fragments perform best in achieving optimal tumour to normal tissue ratios compared with intact IgG and Fab fragment.

Expression of CEA, Tag-72, and Lewis-Y antigen in primary and metastatic lesions of ovarian carcinoma

Ovarian carcinoma has a high mortality rate, because most ovarian carcinomas are detected at a late stage. Traditional therapies, such as surgical debulking and chemotherapy, have not been successful in improving the long-term survival of these patients. Alternative therapies targeting various biomarkers, such as carcinoembryonic antigen (CEA), Tag-72, and Lewis-Y antigen, have been developed to treat patients with advanced ovarian cancers. To ensure that therapies targeting these biomarkers are effective, it is imperative to determine whether there is any differential expression of these targeted biomarkers between primary and metastatic ovarian carcinomas. In the present study, primary and metastatic lesions from 68 and 58 patients, respectively, including primary and matched metastatic lesions from 31 patients, were evaluated for cytoplasmic and membranous expression of CEA (clone Col-1), Tag-72 (clone CC-49), and Lewis-Y antigen (clone BR-96) by immunohistochemistry. No significant differences were observed with cytoplasmic and membranous expression of Tag-72 (CC-49) and Lewis-Y antigen (BR-96) in the primary and metastatic, matched and unmatched lesions (Wilcoxon signed-rank test). Although there was no statistically significant difference in the scores of CEA (Col-1) between primary and metastatic lesions, 5 of 11 (45%) cases with positive staining with CEA (Col-1) demonstrated discordant results between primary and metastatic lesions. There was a moderate positive correlation of the cytoplasmic and membranous expression of Tag-72 (CC-49), as well as cytoplasmic expression of BR-96 between primary and metastatic ovarian carcinomas. There was a weak negative correlation between the membranous expression of CEA (Col-1) and that of Lewis-Y antigen (BR-96); however, the difference was not statistically significant. No correlation was observed with other combinations of biomarkers. Our findings suggest that samples from either primary or metastatic ovarian carcinomas can be used for the evaluation of the expression of Tag-72 (CC-49) and Lewis-Y antigen (BR-96) to identify targets for novel therapies in patients with disseminated ovarian carcinomas. CEA (Col-1), due to its low expression and variation in phenotypic expression between primary and metastatic lesions, should be evaluated carefully in metastatic lesions before targeting the CEA antigen with CEA (Col-1)-like antibodies.

Global approach to hepatic metastases from colorectal cancer: indication and outcome of intra-arterial chemotherapy and other hepatic-directed treatments

Liver metastases of colorectal cancer is present in more than 20% of new diagnosed patients and in 40-60% of relapsed patients. It is a life-threatening prognostic aspect. Hepatic resection, when possible, is the best therapeutic modality, although the overall survival rate is still low (30%). Angiography and intraoperative ultrasonography are useful for resection. The number of hepatic metastases and the surgical margin are probably the most significant prognostic factors. Colorectal cancer may spread predominantly to the liver making regional treatment strategies viable options. Subtotal hepatic resections and segmentectomies are potentially curable procedures for single or small numbers of hepatic metastases without other sites of disease. However, there have been no prospective randomized trials comparing patients with unresected liver metastases and resected metastases. Regional chemotherapy with floxuridine seems usefull combined with hepatic resection or as palliative therapy. Gastric ulcer and biliary sclerosis are the main related toxicities. Patients with localized, unresectable hepatic metastases or concomitant bad medical condition may be candidates for radiation, percutaneous ethanol injection, cryosurgery, percutaneous radiofrequency, hypoxic flow-stop perfusions with bioreductive alkylating agents, hepatic arterial ligation, embolization and chemoembolization. These new hepatic-directed modalities of treatment are being investigated and may offer new approaches to providing palliation and prolonging survival. This review will report the possibilities of intra-arterial chemotherapy and other novel hepatic-directed approaches to the treatment of liver metastases from colorectal cancer.

Intralesional radioimmunotherapy of malignant gliomas. An effective treatment in recurrent tumors

BACKGROUND

Intralesional radioimmunotherapy (RAIT) may improve the management of malignant gliomas whose prognosis is, at present, very poor. Current treatment modalities (e.g., surgery, radiotherapy, and chemotherapy) may prolong survival by a few months but cannot prevent tumor recurrence.

METHODS

Following one or more surgical operations, radiotherapy, and chemotherapy, 24 patients with recurrent malignant gliomas (23 brain and 1 spinal cord) underwent RAIT with 2 murine monoclonal antibodies (MoAb), BC-2 and BC-4, raised against tenascin (TN). This antigen is expressed in large amounts in the stroma of glial tumors but not normal brain tissue. The isotope used was iodine-131 (131I). The radiolabelled antibodies were injected directly into the tumor by means of a removable catheter or an indwelling catheter placed in the site of disease at the time of craniotomy. The patients were admitted to the protocol if histochemical analysis of their tumors demonstrated the presence of TN in high abundance. Biodistribution and dosimetry of an intralesional tracer dose (1 mg MoAb and 37 MBq 131I) were studied. RAIT was performed by the administration of escalating doses of radioiodine, ranging from 15 mCi to 57 mCi. In many cases, RAIT was was repeated two, three, or four times (on 8, 3 and 4 patients, respectively).

RESULTS

Pharmacokinetic data resulted, on average, as follows: the 24-hour tumor/background ratio was 16.6; the percentage of injected dose concentrated per gram of tumor at 24 hours was 2.4%; and the effective half-life of the MoAb at the tumor was 74.5 hours. The mean radiation dose to the tumor was 36.48 cGy per MBq of 131I injected. Both systemic and brain toxicities were absent, while human anti-mouse antibody production after MoAb administration occurred in only a few cases. At present, 17 patients are assessable, with a median survival time of 16 months. Objective responses consisted of 5 tumor stabilizations (median time, 9 months), 3 partial remissions (11 months), and 3 complete remissions (15 months).

Heterogeneity in antigenic expression and radiosensitivity in human colon carcinoma cell lines

A panel of human colon carcinoma cell lines were characterized regarding both antigenic heterogeneity and variations in radiosensitivity. Monoclonal antibodies were used to study the expression of carcinoembryonic antigen (CEA), gastrointestinal cancer antigen (GICA or CA 19-9) and carcinoma-associated antigen (CA-50). Radiosensitivity was studied with the clonogenic survival technique. Three cell lines, LS 174T, HCTC, and SW 1116 stained positive for all three antigens. HT-29 was positive for CA 19-9 and CA-50 whereas Caco-2 was positive for CEA and CA 19-9. The cell lines SW 620 and LIM 1215 only stained positive for one of the antigens, CA-50 and CEA, respectively. In nearly all positive cases the stainings were very heterogeneous with mixtures of positive and negative cells. One exception was the HCTC cells which stained homogeneously for the CA 19-9 and CA-50 antigens. The neuroendocrinelike COLO 320 cells were negative in all cases. The radiosensitivity varied strongly between the cell lines with Dq-values between 0.8 and 1.9, extrapolation numbers between 2.0 and 4.7, Do-values between 1.1 and 2.8. The surviving fraction at 2 Gy varied between 0.3 and 0.7 with HCTC as the most radiosensitive and HT-29 as the most radioresistant cell line. Thus, there were differences in antigenic expression and intrinsic radiosensitivity between the cell-lines and antigenic heterogeneities within each cell line. The analyzed panel of cell lines will be valuable in studies of dose-effect relations for monoclonal antibodies labeled with toxic radionuclides simulating both antigenic heterogeneity and variations in radiosensitivity.

Regional chemotherapy for colorectal hepatic metastases using degradable starch microspheres. A review

Biodegradable starch microspheres (DSM) given by intra-arterial injection provide a way of improving the delivery of cytotoxic drugs to hepatic metastases and simultaneously reducing systemic toxicity. Their effect depends on exploiting the different vascular properties of neoplastic and healthy tissue. Although clinical evaluation is at an early stage, the ability of DSM to produce a selective increase of drug concentration in hepatic metastases represents an improvement on conventional techniques of regional chemotherapy.

Biodegradable emboli and antibody targetting of colorectal and gastric hepatic metastases: a pilot study

The effect of degradable starch microspheres (DSM) on the passage of a low molecular weight marker through the liver of patients with metastases was compared with the passage of an anti-carcinoembryonic antigen monoclonal antibody. In all six patients studied DSM reduced the passage of the marker into the systemic circulation. In three patients who received labelled whole antibody, DSM had no effect. In two of three who received antibody fragments a similar delay to the low molecular weight marker was observed. This delay is likely to be a result of the smaller size of the fragments and may represent accumulation within the extravascular space.