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The membrane bound, tumour associated antigen CA125 is recognized by the monoclonal antibody OC125 and may be detected in tumour tissue and serum in over 80% of patients with epithelial ovarian carcinomas. A total of 13 immunoscintigrams using 111 MBq 131I-OC125 have been performed in 11 patients. The results have been compared with clinical examination, CT and ultrasound scans, surgical findings and serum CA125 concentrations. Macroscopic disease was present at the time of scanning in 11 patients (less than 2 cm, eight patients, greater than 2 cm, three patients). Clinical examination and ultrasound were positive in three, CT scanning in four, immunoscintography in seven and serum CA125 in eight patients. This pilot study suggest that serum CA125 estimation is the most sensitive indicator of disease activity. However, immunoscintigraphy using this agent may localize residual disease when clinical examination and other radiological investigations fail.

Nine patients with adenocarcinoma of the ovary were given a number of courses of Cisplatin, by I.V. infusion. In four patients a complete clinical response was observed and these patients are disease-free one year after treatment. There was no clinical response in the remaining five patients who have subsequently died. Serial determinations of three acute-phase reactant proteins (alpha 1-acid glycoprotein, haptoglobin, alpha 1-antitrypsin) were performed before every infusion and after therapy. Constantly high or rising serum levels of haptoglobin and alpha 1-acid glycoprotein were associated with progression of the cancer, whereas in patients who were disease-free after therapy, these glycoproteins remained essentially in the normal range. The results suggest that serial measurements of haptoglobin and alpha 1-acid glycoprotein may have clinical value as aids in deciding the effectiveness of drug therapy in these patients.

We have fitted a first-order multicompartment pharmacokinetic model to plasma platinum concentrations measured in nine ovarian cancer patients who received intravenous infusions of cisplatin for 6 h. The time-course of ultrafilterable plasma platinum was similar in all patients studied, and was fitted by a single compartment within the limits of experimental detection. However, the time-course of protein-bound platinum showed marked differences between patients, the differences being explained by distribution to two peripheral compartments. The wide inter-patient variation observed in protein-bound plasma platinum concentrations supports the view that pharmacokinetic modelling should be carried out separately for each patient, since averaging plasma concentrations would have obscured some individual pharmacokinetic characteristics.

The presence of cancer antigen CA125 has been assessed immunohistologically in formalin-fixed tumor tissue and immunoradiometrically in serum from 41 women with residual epithelial ovarian carcinoma after diagnostic laparotomy. CA125 was detected in tumor tissue from the majority of patients (34/41), including those with normal serum levels (15/18). The major determinant of serum CA125 concentration appears to be the size of the residual tumor. The results suggest that in the majority of patients with small residual tumor masses and normal postoperative serum antigen levels, progressive disease may well be associated with increasing serum CA125 levels.

An immunoradiometric assay, that uses a monoclonal antibody attached to a solid support and developed for the detection of the ovarian tumour antigen, CA125, in serum, has been evaluated. The method was simple to perform, with reagents having a shelf-life of approximately 4 weeks. The potentials and limitations of this test are discussed.

Twenty-one patients with adenocarcinoma of the ovary were given a maximum of five courses of CDDP by i.v. infusion every 4 weeks. With one exception, the serum levels of both haptoglobin and alpha 1-acid glycoprotein correlate with tumour burden before therapy and at follow-up. It is suggested that a more accurate assessment of the effectiveness of CDDP therapy may be obtained by estimating these serum proteins before each infusion than by an abdominal examination.

Serum CA125 concentrations are elevated in 60% (49/86) of patients, with histologically proven residual adenocarcinoma of the ovary, before chemotherapy. The frequency of elevated levels correlates with stage of disease and tumour size but not histological tumour type. Serial antigen determinations in 44 patients receiving monthly i.v. infusions of platinum therapy suggest that an elevated serum CA125 concentration after chemotherapy may identify the presence of residual tumour but a serum antigen level falling into the normal range does not always indicate the complete eradication of tumour. The role of this serum marker is limited by lack of sensitivity for small tumour masses.