Major drawbacks associated with in vitro assays for sensitivity of tumors to specific chemotherapeutic drugs include the uncertainty of end point validity, the need for large tissue samples, and cost. Furthermore, these assays do not address the question of conversion of the drug to active moities by metabolic pathways in the host or alteration of drug activity by binding to plasma protein. We propose to develop a cell culture technology for growth and quantitation of tumor cells in small pore diffusion chambers which contain the tumor cells and protect them from the immune system of the immunologically unrelated host. In Phase I of the study, the manufacturing technologies and methods will be developed to reliably produce sterile cell growth chambers which can be easily utilized in the analytical laboratory. Theoptimum chamber size, cell inoculum, membrane characteristics, and materials for construction will be determined. Work planned for later phases of this program include investigations of the growth characteristics of human tumors in cell growth chambers studies to determine if fibroblast overgrowth is a problem in this culture system and if so, how it can best be prevented, evaluation of the monolayer culture step in the proposed assay protocol with regard to both biolgical necessity and cost effectiveness, evaluation of drug access to the interior of the chamber, and development of an operating room kit which will enable the operating surgeon to begin processing the specimen at the time of surgical removal in order to increase the percentage of tumor specimens which can be grown in the cell culture system. The antineoplastic drug sensitivity assay which will be based on this cell culture system can be performed with the basic equipment and personnel available in most cell culture laboratories and requires a small number of tumor cells. Mass production of the diffusion chambers may make the assay less costly and faster than assays which do not involve exposure of tumor to drug in a living host and permit screening of new chemotherapeutic drugs against human tumors under physiological conditions.