Let's Not Minimize the Impact of Progression-Free Survival

Mark G. Kris, MD


November 08, 2019

This transcript has been edited for clarity.

Hi. This is Mark Kris from Memorial Sloan Kettering. I'm commenting today about an article that appeared in the October 1 print edition of the Journal of Clinical Oncology, by Eddie Garon.

I was looking forward to this paper because I was so impressed by Eddie's presentation at this year's American Society of Clinical Oncology (ASCO) meeting. Eddie gave an unbelievable talk about the impact of the long disease-free, relapse-free survival achieved by patients who received checkpoint inhibitors. He made the point that by putting their disease at bay, patients got their lives back, which was the most important thing.

Nowhere in this paper did I see the very dramatic impact of these findings or even the passion that Eddie had the day of his presentation. Also nowhere in this paper or the accompanying editorial is the word "cure." I think people are afraid to use the word "cure." If you are disease-free at 5 years, I think it's a word that can be used. For oncologists, trying to achieve cure is something we have to think about, and if we don't think about it, it's never going to happen.

While this paper was helpful, it talked about things that were not quite as important, such as whether the responses occurred early or late and whether the responses and durations were different in people who had it as the first treatment or subsequent treatment. Of course they are going to be different. People who get subsequent treatments as a class live longer than people who only get the first treatment. They have to live long enough to get the subsequent treatment. Also, there is nothing about this drug [pembrolizumab] to suggest that its effectiveness would be dramatically influenced by first or subsequent treatment.

The real outcome that I was looking for was a line in one of the tables: patients with a response who had not progressed—a total of 79 out of the 550 patients (14%) were in continuous remission. There also were no survival curves about progression-free survival in this paper. Of course survival is important, but our patients want their cancer controlled and ideally to be cancer free. This is what we need to shoot for.

We should not be afraid to talk about cure. We should not think about it as a goal because it's very hard to achieve; but until these drugs came along, we never achieved it. Many of us have toiled in the field of targeted therapies, and it's sad to say that other than in the adjuvant and neoadjuvant setting, there isn't a good demonstration that we can add to the curability of lung cancers with targeted therapies. However, we have been able to do that with immunotherapy, which is an amazing achievement, but we can do so much more.

Let's not miss the real message that Eddie gave us at the ASCO meeting: Patients have been able to achieve relapse-free survival. Our goal is to find out how to achieve this in more patients. We need to focus on getting the cancer under control and keeping it there for as long as possible. In this clinical trial, 14% of patients did not have their cancer grow back in 5 years. I think many of us would say that those people very possibly are cured, and I wouldn't be afraid to say it.

Mark G. Kris, MD, is chief of the thoracic oncology service and the William and Joy Ruane Chair in Thoracic Oncology at Memorial Sloan Kettering Cancer Center in New York City. His research interests include targeted therapies for lung cancer, multimodality therapy, the development of new anticancer drugs, and symptom management with a focus on preventing emesis.

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