This is Dr. Paul Chapman from Memorial Sloan Kettering Cancer Center. And here's something you might want to know. Immunotherapy has revolutionized the treatment of melanoma. And we can now expect most patients to have their melanomas shrink as a result of immunotherapy.
Some patients experience complete disappearance of melanoma. And we call this a complete response. And in these patients, we eventually stop treatment altogether and follow the patients with scans. Since these immunotherapy drugs were only approved relatively recently, the first coming in 2011, we don't yet know if these patients are all cured, or if the melanoma comes back sometimes.
At the recent meeting of the American Society of Clinical Oncology, we got some good news about these patients. Four different groups of melanoma doctors reported studies of patients who discontinued treatment after a complete response to anti-PD-1 therapy. And these patients who had been treated either with pembrolizumab, also known as Keytruda, or nivolumab, also known as Opdivo, had been off treatment for a median of 16 to 22 months. During that time, only 7% to 10% had relapsed.
Of course, we will need to follow these patients longer to see if there are any other relapses. But at least within the one and half to two year range after stopping treatment the relapse rate is pretty low.
Patients often want to know whether anti-PD-1 treatment can be effective a second time if they are among the unlucky few who relapse. Results were presented on only 22 patients who relapsed after a complete response and then were retreated again. But among these 22, half of them responded a second time.
So the message is that for melanoma patients who have a complete response to anti-PD-1 immunotherapy the relapse rate is very low, at least within the first one and half to two years. And relapsing patients can respond the second time.
As we follow these patients longer, we will learn whether or not relapses can happen even later. And if not, maybe we will find that patients don't need so many follow-up scans. More to come.