CHICAGO – Secondary cytoreductive surgery resulted in a clinically meaningful increase in progression-free survival and time to first subsequent therapy in a phase III study of carefully selected women with ovarian cancer who experienced their first relapse after a platin-free interval of 6 months.
These interim findings from the randomized international DESKTOP III trial suggest that until final overall survival data are available to more definitively define the role of secondary cytoreductive surgery in this setting, it should at least be considered as an option in patients who are good candidates based on a positive AGO Study Group score, defined as an ECOG performance status score of 0, ascites of 500 mL or less, and complete resection at initial surgery, Andreas du Bois, MD, reported at the annual meeting of the American Society of Clinical Oncology.
The median progression-free survival (PFS) in 204 women who met this criteria and who were randomized to undergo surgery followed by chemotherapy was 19.6 months, compared with 14 months in 203 women who were randomized to receive only second-line chemotherapy (hazard ratio, 0.66), said Dr. du Bois of AGO and Kliniken Essen-Mitte, Essen, Germany.
“Even more important ... only complete resection makes a difference ... and that adds a median 7.2 months PFS with a hazard ratio of 0.56, which is highly significant. Fortunately that translates into time to first subsequent treatment, which is a more patient-oriented outcome,” he said.
The time to third-line therapy was prolonged by a highly statistically significant median of 7.1 month (hazard ratio, 0.6).
“What was the trade-off for these benefits? The patients did not pay for it with excessive mortality,” he said, explaining that no significant differences were seen between the groups in terms of mortality at 30, 60, 90, or 180 days, and that no excessive toxicity or treatment burden was seen in either group.
Median age of the patients was 60 years; they were enrolled at 80 centers in 12 countries between 2010 and 2015. The platin-free interval exceeded 12 months in 75% and 76% of patient in the surgery and control arms, respectively.
Chemotherapy regimens in both the treatment and control arms were selected according to institutional standards, although platinum-based combination therapy was strongly recommended; 87% and 88% in the groups, respectively, received a platinum-containing second-line therapy.
Macroscopic complete resection was achieved in 72.5% of patients in the surgery arm, which was the rate predicted by the AGO scores.
“We know that the surgery and chemotherapy are the cornerstones of ovarian cancer therapy ... however, surgery in recurrent ovarian cancer has not been based on high-level evidence,” Dr. du Bois said. “So far there are only retrospective series suggesting that there might be a benefit or not.”
The German AGO group and the Gynecologic Oncology Group (GOG) in the United States thus initiated clinical trials to evaluate its role in recurrent ovarian cancer, including the DESKTOP series, he explained, noting that thewas developed through these trials as a way to identify good surgical candidates based on preoperative factors.
It was confirmed in a prospective study that the score, which selects about 50% of all patients with platinum-sensitive recurrent ovarian cancer, could predict successful surgery, he added.
In the current study, the data with respect to overall survival – the primary study endpoint – have not reached maturity, but at 2 years it was 83%.
However, the findings of a meaningful benefit in progression-free survival and time to first subsequent treatment (advantages of 5.6 and 7.1 months, respectively) in secondary cytoreductive surgery patients is at least comparable with all phase III trials in second-line therapy for platinum-sensitive recurrent ovarian cancer so far, he said.
“In fact, it’s the most positive trial ever reported in this population,” he added, noted that he was referring to therapy trials, not maintenance trials.
Further, the fact that the surgery benefit was exclusive to patients with complete resection indicates the importance of selecting both the right center with capability of achieving complete resection in most patients, and the right patients, as identified by the AGO score.
“Hopefully, further follow-up will show that this benefit translates into overall survival,” he concluded, noting that overall survival will be evaluated after extended follow-up when 244 overall survival events are observed.
Dr. Du Bois reported serving as a consultant or adviser for AstraZeneca, Mundipharma, Pfizer, Pharmamar, and Roche/Genentech.