Further experience in testing the sensitivity of human ovarian carcinoma cells to interferon in an in vitro semisolid agar culture system: comparison of solid and ascitic forms of the tumor

Abstract

We studied the in vitro growth characteristics of 10 solid-tumor samples of patients with ovarian carcinoma using a semisolid agar culture technique. Tumor cell colonies were observed in 8 of 10 samples, but sufficient number of tumor colonies to evaluate the effects of interferon and other antitumor agents were obtained in only four samples. As compared with cell suspensions prepared from ascitic fluid samples, solid-tumor samples had markedly lower viability, 39% vs 89%, and had more tumor cells, 81% vs 28%. Also, whereas the maximum increase in tumor-colony number occurred during the first week of growth in both solid- and ascitic-fluid-derived samples grown concurrently from the same donors, increase in tumor colony number was sustained for longer periods in ascitic-fluid-derived cultures. The ascitic-fluid-derived tumor colonies were more sensitive to the antiproliferative effects of interferon than colonies derived from solid-tumors. At a concentration of 300 units/ml incorporated into the agar for the duration of the culture, three of four ascitic fluid samples showed a reduction in tumor colony number by greater than or equal to 25%, whereas none of the solid-tumor samples were affected by the interferon to that degree. In contrast, solid-tumor samples showed greater response to cis platinum and Adriamycin than did ascitic-fluid-derived cultures. Such studies and observations are critical in designing clinical trials for the use of interferon in the treatment of malignancy and the judicious selection of patients and route of administration most likely to provide optimal results, especially in view of present critical shortages in availability of interferon.