Drug development in solid tumors: personal perspective of Dr. Emil J Freireich's contributions

The development of chemotherapy for patients with the major cancers progressed from the initial success attained in the treatment of acute leukemias and choriocarcinoma. Many of the principles of therapy were based on the concepts developed in the experimental laboratories and early clinical studies done at the NIH Clinical Center and other centers around the country. The purpose of this review is to describe some of the early advances in cancer therapy and show how many are based on the efforts of Dr. Emil J Freireich. Over his career, Dr. Freireich has published more than 500 papers and worked on more than 70 different drugs and combinations. The principles defined by Dr. Freireich, namely, the use of intermittent intensive chemotherapy to induce complete remissions (CRs), intensification of therapy in remission, and the use of unmaintained remissions to assess cure, have been important in developing curative chemotherapy programs in patients with acute leukemias. These same principles were applied to combination therapy of Hodgkin's disease as the nitrogen mustard, vincristine, procarbazine, and prednisone combination was developed. This led to the high CR and cure rate for this disease. The treatment of metastatic breast cancer does not produce a high proportion of CRs, and cures of metastatic disease are unlikely with chemotherapy alone. But adjuvant chemotherapy after surgery has resulted in a significant reduction in cancer mortality. Many challenges remain in increasing the cure rate for the major solid tumors. New avenues of controlling cell growth and metastases need to be explored. One approach that is exploitable is the use of drugs or nutrients to prevent cancer. Laboratory approaches are now becoming a clinical reality.