JOHN HAYS: In ovarian cancer, we have a spectrum of patients. Almost all patients in the front line are treated with cytotoxic chemotherapy, generally a platinum-containing chemotherapy paclitaxel, and if possible, cytoreductive surgery. The key being that the majority of patients, unfortunately, with ovarian cancer, will recur. And although we've come a long ways in recent history with maintenance therapies after front-line chemotherapies that have helped a number of patients, we still see the majority of patients that are diagnosed with ovarian cancer at some point developing platinum-resistant ovarian cancer.
And platinum-resistant ovarian cancer is an incredibly difficult disease to treat. We've been trying for many years to develop new agents and new drugs to try to help our patients in this space, and we still use a phase III trial published almost 12 years ago, which is our baseline reference for chemotherapy in the platinum-resistant setting. That trial was called AURELIA, and in that setting, chemotherapy plus Avastin had a median progression-free survival of about six months. Whereas, chemotherapy by itself was about three months. And there was a small but not clinically significant benefit in overall survival for adding Avastin to chemotherapy. But it goes to show that that is still the control arm for many of our clinical trials in the platinum-resistant space.
More recently, the approval of Elahere, which is an antibody drug conjugate to the folate receptor, as well as the generalized approval for HER2 antibody drug conjugates across multiple diseases, have both helped subsets of population in platinum-resistant ovarian cancer. But overall, we still are stuck with chemotherapies that don't work near as well as we would like them to.
We have tried immunotherapy in a number of different settings with ovarian cancer. We've tried immune checkpoint inhibitors in the frontline setting, in the maintenance setting, as well as in the platinum-resistance setting. And historically, the response rates to checkpoint inhibitors, especially with platinum-resistant ovarian cancer, have been in the 10% range with not a significantly meaningful improvement in progression-free or overall survival.
And so at the current time, there are no approved immune therapies in platinum-resistant or even in platinum-sensitive ovarian cancer. Although, we've investigated them in a number of different settings. Currently under clinical development are a number of different types of immune therapies, including checkpoint inhibitors and bispecific T-cell engagers, as well as cellular therapies, which may hold some promise but are still a ways away from reaching clinical fruition.
