- Nearly one in five lung cancer patients treated with Merck & Co.'s immunotherapy Keytruda in an early study of the drug were alive five years later, a marked improvement over the average five-year survival rate of just 5% in the years before immuno-oncology's emergence.
- The results, presented Saturday at the American Society of Clinical Oncology's annual meeting, represent the longest follow-up of advanced lung cancer patients given Keytruda, and highlight the lasting responses a subset of people can have to immunotherapy treatment.
- Still, even with Keytruda, most don't survive five years. Researchers are still searching for better ways to predict who will fare best on immunotherapy, while drugmaker efforts to expand the benefit of Keytruda and drugs like it through combination treatment have been mixed.
Keynote-001, the Phase 1b study which yielded the results presented Saturday, is the foundation for Keytruda's initial clinical advances and led in part to the drug's first approvals in melanoma and lung cancer.
Now, more than eight years after that trial began, five-year survival data go some ways to defining the long-term benefit of immunotherapy.
"In previous years, we would see a patient with metastatic, non-small cell lung cancer, and unfortunately we'd have to paint a pretty gloomy picture," said David Graham, medical director at the Levine Cancer Institute in Charlotte, North Carolina, in an ASCO briefing with reporters.
"Now, as we look at this data in patients appropriately treated with [Keytruda], one in four of them or more are going to be around five years from now and that completely changes our mindset."
Survival rates varied depending on whether patients were previously treated and on whether their tumors expressed high levels of a biomarker known as PD-L1.
Those previously untreated fared better, with 23% alive at five years, compared to more than 15% among patients who had undergone prior treatment. Survival was particularly pronounced for the 60 individuals in the study who had received Keytruda treatment for two years or more, with 45 alive at five years.
Notably, researchers found late-onset toxicity from treatment was rare, with rates of immune-mediated adverse events roughly similar at three and five years.
Five-year survival rates by patient group
|# of patients||5-year overall survival rate|
|Previously untreated, PD-L1 high||27||29.6%|
|Previously treated, PD-L1 high||138||25%|
SOURCE: Study abstract
According to data from the National Cancer Institute, the five-year survival rate metastatic non-small cell lung cancer (NSCLC) between 2008 and 2014 was roughly 5%.
Since Keytruda first won approval for lung cancer in 2015, Merck has steadily added to the evidence supporting the drug's use in more and more patients.
Keytruda is now cleared for first-line use in combination with chemotherapy for nonsquamous and squamous lung cancers, as well as by itself in patients whose tumors express PD-L1.
Those approvals have led to rapid commercial gains for Merck, which now leads the immuno-oncology field in quarterly sales. Despite clinical and commercial success, however, answers for those patients who don't see a benefit have been less forthcoming.
"We still have a long way to go to improve outcomes for all advanced NSCLC patients," Graham said.