Current results of the screening program at the division of cancer treatment, national cancer institute

The prospective screening program at the Division of Cancer Treatment, National Cancer Institute, has now been in operation for several years and is making steady progress in the identification of new synthetic compounds and natural products of potential interest for the clinic. Data are presented on four categories of drugs that have been tested in the new screening panel: (a) clinically established antitumor agents; (b) new drugs and drugs for which there is renewed clinical interest based on activity in the new screen and previously inadequate clinical trial; (c) drugs in the initial phases of clinical trial; (d) compounds in development. An analysis of the data is presented, taking into account a series of important questions that are being addressed prospectively to the new screen. Although the ability to provide definitive answers must await feedback from clinical testing of compounds recommended by the screen, some generalizations appear to be emerging, and these are discussed. A comparison is made of the activity of drugs in the treatment of human tumors growing in two sites, subcutaneously and under the renal capsule. The subrenal capsule model appears to be somewhat more sensitive to drugs than the subcutaneous model and may provide certain advantages for initial panel testing. Attention is drawn to the potential usefulness in a screening program of the newly developed clonogenic techniques for growing human tumors. The screening program at the Division of Cancer Treatment is viewed as a dynamic entity, subject to modification in accordance with acquired experience.