The expert discussed study methods from the NRG Oncology/Gynecologic Oncology Group (GOG) study presented at the 2020 ASCO Virtual Program.
At the 2020 ASCO Virtual Program, Robert L. Coleman, MD, FACOG, FACS, discussed study results from the NRG Oncology/Gynecologic Oncology Group (GOG) study – a phase 3 randomized controlled trial of secondary surgical cytoreduction followed by platinum-based combination chemotherapy, with or without bevacizumab (Avastin) in platinum-sensitive, recurrent ovarian cancer.
In an interview with CancerNetwork, Coleman, chief scientific officer of US Oncology Network, discussed the study methods.
GOG 213 is a little different than the others. And I highlighted this also in my discussion, but the GOG 213 trial was initially set up to address two questions. So, the first question was whether or not bevacizumab could be added to chemotherapy. And would that be better than just chemotherapy alone? Well, that particular question became very relevant for interpretation of the second question, which was, can surgery improve the overall survival of women who have recurrent ovarian cancer who would otherwise be good candidates for chemotherapy as well?
The first question, basically randomized women who were not necessarily good surgical candidates, but with recurrent platinum-sensitive, recurrent ovarian cancer, and they were all administered in a 1:1 randomization if either platinum-based combination chemotherapy, or PACs, or platinum and bevacizumab, followed bevacizumab and maintenance until progression. And the primary end point of that trial was overall survival.
So in that trial, with 674 patients, we showed that there was an improvement in overall survival. And of course, there was also an improvement in progression-free survival. But when that particular trial finished the accrual it needed to finish the question, we only allowed patients to enroll into the surgical question.
So the second cohort of patients to address the second question was a better prognostic group because they were selected for the capability of being able to do a complete gross resection. So their tumor volume was low and we felt that it could be completely resected. So then all of those patients, whether they were randomized to surgery or not, then went on to get chemotherapy.
At that point in time, the chemotherapy question had already been answered, so there was no more randomization to practice. In fact, you could tell just from the way that the trial ran that the first cohort finished so quickly, because there's many, many more patients that are not good surgical candidates then who are, but are good candidates for chemotherapy, so that already tells you how there's such a selection bias going on for selection of these patients. So when that happened, then we went ahead and conducted the second cohort. We left the chemotherapy choice to the discretion of the investigator. And because at that time, we had already proved that there was a survival advantage, many of the investigators in the United States used bevacizumab as part of that regimen and that ultimately comes back to be a really important aspect of this trial.