More than a third (35%) of patients with relapsed non–small cell lung cancer (NSCLC) treated with pembrolizumab (Keytruda, Merck) were still alive at 3 years, according to long-term results from a pivotal clinical trial.
The results also showed that, among the 10% of patients who completed all 35 cycles of pembrolizumab, the 3-year overall survival was approximately 99%, with progression-free survival (PFS) at around 70%.
“It is too soon to say that pembrolizumab is a potential cure...and we know that it doesn’t work for all patients, but the agent remains very, very promising,” said lead investigator Roy Herbst, MD, PhD, Department of Medical Oncology, Yale Comprehensive Cancer Center, New Haven, Connecticut.
These new results come from the KEYNOTE-010 trial, conducted in more than 1000 patients with NSCLC who had progressed on chemotherapy, randomized to receive immunotherapy with pembrolizumab or chemotherapy with docetaxel.
The results were published online on February 20 in the Journal of Clinical Oncology and were previously presented at the 2018 annual meeting of the European Society of Medical Oncology.
Overall survival at 3 years was 35% in patients with PD-L1 expression ≥ 50% in the tumor, and 23% in those with PD-L1 ≥ 1%.
This compares with 3-year overall survival of 11-13% with docetaxel.
These results are “really extraordinary,” Herbst commented to Medscape Medical News.
The 3-year overall survival rate of 35% in patients with PD-L1 ≥ 50% “is huge,” he said. “It really shows the durability of the response.”
Herbst commented that the “almost 100%” survival at 3 years among patients who completed 35 cycles of pembrolizumab shows that this treatment period (of about 2 years) is “probably about the right time to treat.”
“Currently, the agent is being used in all potential settings, before any other treatment, after other treatment, and with other treatments,” he said.
“Our hope is to find the very best way to use pembrolizumab to treat individual lung cancer patients, assessing how much PD-L1 a tumor expresses, what stage the patient is in, as well as other variables and biomarkers we are working on. This is the story of tailored therapy,” Herbst said.
Approached for comment, Solange Peters, MD, PhD, Oncology Department, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, said that the results are “very good” and “confirm the paradigms we have been seeing in melanoma,” with good long-term control, which is “very reassuring.”
However, she told Medscape Medical News that the trial raises an important question: «How long do you need to expose your patient with lung cancer to immunotherapy in order to get this long-term control?»
She said the “good news” is that, for the 10% of patients who completed 2 years of treatment per protocol, almost all of them are still alive at 3 years, “which is not observed with chemotherapy.”
The question for Peters is “more about the definition of long-term control,” as it was seen that almost one in three patients nevertheless had some form of progression.
This suggests that you have a group of people “who are nicely controlled, you stop the drug, and 1 year later a third of them have progressed.”
Peters said: “So how long do you need to treat these patients? I would say I still don’t know.”
“If I were one of these patients probably I would still want to continue [on the drug]. Of course, some might have progressed even while remaining on the drug, but the proportion who would have progressed is probably smaller than this one.”