Characterization of in vitro chemosensitivity of perioperative human ovarian malignancies by adenosine triphosphate chemosensitivity assay Robert T. Gerhardt, MPH, James P. Perras, PhD, Bernd-Uwe Sevin, MD, PhD, Edgar Petru, MD, Reinaldo Ramos, BS, Lucy Guerra, and Hervy E. Averette, MD Miami, Florida We report the in vitro chemosensitivity of primary and recurrent human ovarian tumor samples analyzed by adenosine triphosphate chemosensitivity assay. We defined sensitivity as a decrease in intracellular adenosine triphosphate versus control at 20% of the reported peak plasma concentration per agent tested. Twenty of 21 assays (95.24%) were completed successfully. Single-agent and combined dose-response patterns consisting of decreasing viability with increasing drug concentration were observed consistently. Thirteen primary tumors were assayed, with 15.4% sensitive to cisplatin, 7.7% sensitive to 4-hydroxycyclophosphamide and 53.8% sensitive to their combination. Seven recurrent tumors were assayed, with 14.3% sensitive to cisplatin, 28.6% sensitive to 5-fluorouracil, and 42.9% sensitive to their combination. Dose-response characteristics and in vitro sensitivity rates reported in this article are consistent with reports of patient response in the literature. We conclude that adenosine triphosphate chemosensitivity assay is an efficient and reliable instrument for the in vitro chemosensitivity assessment of human tumors and warrants further clinical investigation. (AM J OSSTET GYNECOL 1991 ;165:245-55.) Key words: Adenosine triphosphate chemosensitivity assay, bioluminescence, chemosensitivity, ovarian cancer Researchers and clinical oncologists have long rec- ognized the potential value of pretreatment assessment of chemosensitivity for patients with cancer. 1 Efforts in this direction to date have produced mixed results! The issues of in vitro evaluability, heterogeneity of tu- mor subpopulations," emerging drug resistance: and the questionable role of clonogenic or stem cells in ma- lignancy have provided formidable obstacles to the de- velopment of an in vitro assay possessing in vivo predictive value. Assays such as the human clonogenic assay, succinate dehydrogenase inhibition, and radio- active thymidine uptake index are often inconclusive, and they possess a high rate of nonevaluability.5.7 Con- sequently, in vitro chemosensitivity testing to date has remained primarily within the purview of the basic sci- entist, leaving the clinician to select chemotherapeutic regimens on an empiric basis. From the Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of Miami School of Medicine. Supported in part by the John R. McCain Medical Student Research Fellowship, South Atlantic Association of Obstetricians and Gynecol- ogists, and the Doris Kleiber Memorial Fund, University of Miami. John R. McCain Fellowship Lecture, presented at the Fifty-third Annual Meeting of the South Atlantic Association of Obstetri- cians and Gynecologists, Hot Springs, Virginia, January 27-30, 1991. Reprint requests: Bernd-Uwe Sevin, MD, PhD, Division of Gyne- cologic Oncology, Department of Obstetrics and Gynecology (D-52), University of Miami School of Medicine, P.O. Box 016190, Miami, FL 33101. 6/6/30756 Ovarian malignancy is a formidable disease for the patient and a challenge for the clinician. Its insidious onset with relatively late detection, high malignant po- tential, tendency toward early metastasis, and rapid de- velopment of resistance to chemotherapy contribute to a generally poor prognosis for the afflicted patient. 8 The standard treatment for both primary and recur- rent malignancy includes cytoreductive surgery fol- lowed by adjuvant chemotherapy with one or a com- bination of several agents, commonly including cis- platin and cyclosphosphamide. 5-Fluorouracil (5-FU) is sometimes used in the salvage therapy of recurrent malignancies. Prognosis is related to clinical stage, histologic grade, tumor type, the amount of unresect- able residual tumor at the time of cytoreductive sur- gery, and response to postoperative adjuvant chemo- therapy. The adenosine triphosphate (ATP) chemosensitivity assay has been reported as an efficient, highly evalua- ble, and cost-effective means of characterizing the in vitro chemosensitivity of cell lines and fresh human tumors, with promising preliminary clinical correla- tions. g · ll With ATP extraction by acid cytolysis and mea- surement by luciferin-Iuciferase bioluminometry, ATP chemosensitivity assay assesses chemotherapeutic-in- duced cell kill of the entire tumor sample (including proliferative and non proliferative subpopulations) by comparing total ATP concentration in treated samples versus untreated controls. Total ATP concentration as 245