UCLA Med Center's Dr. Eddie Garon discusses the open question of the optimal duration of ongoing treatment with immunotherapy for lung cancer.
The duration of therapy that’s appropriate for immunotherapy is very hard to know. There are not good studies, to date — there are some theoretical reasons that you could go either way, that being, you could say that you’re going to need to treat these patients forever, versus that you would need to treat patients for a period of time. Different clinical trials have had different durations of therapy — there are some trials that have treated until the time of progression, there are some trials that have treated patients for one year, some trials that have treated patients for two years. We certainly know that there are some people who, for a variety of reasons, need to come off drug for a period of time, who will continue to do well after going off drug for even long periods of time; whether that means that these patients can stop the drug, we don’t know. Also, many of the toxicities tend to be seen early, but there are patients that can have toxicities that are seen late, so it’s not that there is no harm in continuing to treat a patient who is doing well — there may be harm, they may derive no additional benefit but some risk of additional toxicity.
The answer is: we don’t know yet. There are studies that are under way that are trying to evaluate this question, but in reality, those studies are very, very hard to conduct, they take a long time to get results, and you have to enroll a huge number of people upfront, knowing that only a percentage of those patients are going to still be on drug a year later, and it does end up being a very difficult question to answer. I think, in many respects, these questions are going to be answered in our clinics. There will also probably be payers that have some input into this. In my clinic, I tend to have a lot of people who, you know, sort of — that’s where we reached out for clinical trials of immune checkpoint inhibitors, and those people are terrified of stopping their drug; they understand that it may be the wrong thing to continue it after years, but they still want to continue it. On the other hand, patients who are seen in a practice that is not the same as mine, where they’re maybe not quite as motivated, they’re not the people who have flown in for a checkpoint inhibitor every few weeks, that group of people may get sick of coming in for the drug, and they may choose to stop it, and that may be where our data comes from — although, as I say, there are studies that are ongoing, the CheckMate 153 study looking at Opdivo will look to address that question, but again, studies like that take a long time to answer their question, if they can answer it at all.