Researchers compared weekly doses of Taxol (paclitaxel) to treat ovarian cancer with dosing every three weeks in a European trial to determine if weekly dosing was more effective. They found that weekly dosing did not extend progression-free survival (PFS) in this patient population.
The results were surprising because an earlier Japanese trial, JGOG3016 (NCT00226915), had shown that weekly dosing was more effective than dosing every three weeks. Researchers are attributing the difference in results to genetic differences between Caucasians and Asians.
The results of the ICON8 Phase 3 trial (NCT01654146) were highlighted in the poster, “ICON8: A GCIG phase III randomised trial evaluating weekly dose-dense chemotherapy integration in first-line epithelial ovarian/fallopian tube/primary peritoneal carcinoma (EOC) treatment: Results of primary progression-free survival (PFS) analysis,” presented at the European Society for Medical Oncology (ESMO) 2017 Congress.
The purpose of the trial was to determine if weekly chemotherapy to treat ovarian cancer by giving Taxol and Paraplatin (carboplatin) at a lower dose every week is more effective than the standard chemotherapy regimen of Taxol and Paraplatin given once every three weeks over 18 weeks.
“The results clearly demonstrate that, although well-tolerated, using weekly scheduling to achieve dose-intensification of paclitaxel as part of the first-line treatment of epithelial ovarian cancer does not extend progression-free survival in this population,” study investigator Dr. Andrew Clamp, from the Christie NHS Foundation Trust and the University of Manchester, in the U.K., said in a press release. “Therefore, this approach cannot be recommended as a standard-of-care treatment option for this population.”
He added that, “it remains appropriate to continue to offer weekly dose-dense paclitaxel as a treatment option to Japanese women.”
All patients entered ICON8 after a first surgery or after receiving chemotherapy with planned, but delayed, surgery.
The ICON8 trial included 1,566 predominantly European patients who received the standard three-week dose of Paraplatin and Taxol, or two other regimens that included Taxol once-weekly, with Paraplatin (carboplatin) at two different doses.
The once-weekly dosing of Taxol was slightly more toxic (53-63% of patients) than the dose taken every three weeks (42%). PFS was 24.4 months with standard treatment compared with 24.9 and 25.3 months in the once-weekly study groups.
Commenting for ESMO, Domenica Lorusso, MD, PhD, from Fondazione IRCCS National Cancer Institute of Milan, and chair of the Gynecological Tumors track at ESMO 2017, said at the conference: “The trial confirms that carboplatin-paclitaxel every 3 weeks is the standard first line treatment in ovarian cancer, a standard which has remained unmodified in the last 20 years, at least in the Caucasian population.”
Success with weekly dosing in the Japanese population “is possibly due to genetic differences,” she added.