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| |  DG DISPATCH - SGO: Resistance To Cisplatin And Other Second Agents Verified With Assay By Cameron Johnston Special to DG News
NASHVILLE, TN -- March 7, 2001 -- Patients with advanced malignant cervical cancer who do not respond well to initial treatment with cisplatin are not likely to have a good outcome regardless of what second agent might be added to the platinum therapy. Results of a study presented March 6 at the 32nd meeting of the Society of Gynecologic Oncology do not suggest a causal relationship, but do indicate that failure or lack of response to cisplatin and resistance to a second agent frequently go together. The study, which was conducted at the Walt Disney Memorial Cancer Institute, part of the Florida Hospital, in Orlando, involved 97 people whose tumor tissue was sampled in an Extreme Drug Resistance Assay, or EDR (Oncotech Inc.). The original 97 patients were narrowed down to 79 who were followed throughout their chemotherapy regimens. The patients were all chemotherapy-naïve, and all were treated with platinum-based therapy by the same oncology team. Besides the cisplatin, patients were offered cyclophosphamide, paclitaxel or adriamycin as second-line agents. Some received only cisplatin. The median progression-free survival time for the 17 patients who were deemed to be extremely resistant to cisplatin (EDR) was six months compared with 24 months for the 62 subjects who exhibited only a low resistance to cisplatin (RR=2.57). The study was not designed to reflect the efficacy of the drugs, and the fact that some people are resistant to cisplatin, or indeed to all chemotherapeutic agents, is well-documented. The purpose of this study was to determine what the EDR Assay would reveal about resistance or reactions with the second agents. Estimated overall five-year survival for patients with extreme drug resistance was 19 percent, while for those with low drug resistance it was 66 percent (RR=3.57). These results further indicate that there was no significant difference in progress-free survival or overall survival in the 20 patients treated with cisplatin and cyclophosphasmide, or in the 59 others who had either paclitaxel, adriamycin and/or cyclophosphamide, or cisplatin alone. Laboratory test assays of the tumor response to cisplatin remains an independent predictor of progress-free survival and for overall survival adjusted for the chemotherapy administered. Median progress-free survival for all 79 patients in the study was 22 months, while estimated five-year survival was 57 percent. The investigators, headed by Dr. Robert Holloway, chief of the institute, concluded that patients demonstrating in vitro resistance to cisplatin on an Extreme Drug Resistance Assay have a clinically and statistically significant reduction in overall survival and progress-free survival, regardless of what second agent is used. It may be further suggested that patients whose tumors exhibit extreme drug resistance on assay should be monitored closely for early progression and subsequently considered for trials with novel agents and/or alternative combinations of therapy.
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