Sequential single agents as first-line chemotherapy for ovarian cancer: a strategy derived from the results of GOG-132

Abstract

First-line chemotherapy for ovarian cancer during the past decade has evolved toward the use of carboplatin and paclitaxel combinations. This has been based on randomized trials showing that combinations of these two drugs lead to a outcome similar to that obtained using cisplatin and paclitaxel (that had, in turn, proven superior in progression-free survival and overall survival to cisplatin and cyclophosphamide) but with less toxicity. Surprisingly, taxane-platinum combinations were not superior to control arms in two studies (ICON3 and GOG-132) utilizing carboplatin or cisplatin as the comparators. This has renewed interest in the role of single agents in first-line chemotherapy - a concept also supported by a number of prior clinical trials with single-agent platinum compounds yielding results not inferior to combinations. Early 'pre-emptive' crossover (prior to the stipulated clinical progression) to paclitaxel or a paclitaxel-containing regimen, however, occurred in 24% of patients initially treated with cisplatin on GOG-132. This has led to the interpretation of this trial as a combination versus sequential design. Although not subscribing to this interpretation, the results of GOG-132 and ICON3 not only raise doubts over a clear superiority of combinations over single agents but also lead to a consideration of sequential treatment designs for first line. Advantages of such designs are: (a) ability to provide 'dose-dense' platinums followed by 'dose-dense' paclitaxel and, perhaps, other drugs; and (b) the potential of acquiring biological data linked to the antitumor effects of a specific drug. Mathematical modeling and recent positive results in breast cancer adjuvant therapy support the use of 'dose-dense' strategies, and these should be considered in the design of future trials in ovarian cancer.