Five-year survival rates approaching 30% have been seen for some patients with advanced non-small cell lung cancer treated with pembrolizumab, according to the latest results from the KEYNOTE-1 study.

Presented at ASCO 2019, the new findings show that life expectancy for some patients with the disease can now be measured in years rather than months as was the case in the pre-immunotherapy era when five year survival rates were 5.5%, according to the study investigators.

In the study, which involved 550 patients with advanced NSCLC, 101 patients were previously untreated and 449 had received prior treatment.

At five years follow up, overall survival rates were 23.2% for previously untreated patients and 15.5% for patients who were previously treated.

Survival rates were highest among patients with higher PD-L1 expression: 29.6% for patients with PD-L1 expression rates of 50% or more vs 15.7% for patients with PD-L1 expression rates of 1-49% in the previously untreated arm of the study. For patients who had prior therapy the respective 5-year rates were 25% vs 12.6%.

However outcomes were poor for patients with PD-L1 expression levels below 1%, with just 3.5% overall survival at five years.

Among people receiving pembrolizumab who had previous treatment, 42% had responses that lasted a median of 16.8 months. For those who received pembrolizumab as initial therapy, 23% had responses that lasted a median of 38.9 months.

Adverse effects, were seen at levels (17% overall) similar to other trials of pembrolizumab, with pneumonitis the most serious adverse effect, linked to one fatality.

Study investigator Dr Edward Garon, an oncologist at UCLA Jonsson Comprehensive Cancer Center, said the findings showed that overall survival rates had improved substantially in the immunotherapy era.

“The uniformly negative outlook that has been associate with a diagnosis of advanced NSCL is certainly no longer appropriate,” he said.

“The fact that we have patients on this trial that are still alive after seven years is quite remarkable. We also have evidence that most patients who are doing well after two years on pembrolizumab live for five years or more.”

Commenting on the findings, Dr David Graham, an oncologist at Levine Cancer Institute in Charlotte, North Carolina, said the latest findings confirmed those of other immunotherapy trials that showed some patients with advanced NSCLC could now expect to live for five years or more.

“It’s truly remarkable that for more patients than ever before we no longer have to count survival in months,” he said.

“When using immunotherapy in selected patients we have to start thinking about how we deal with our patients. In previous years when we saw a person with metastatic NSCLC, we unfortunately had to paint a very gloomy picture. Their chances of being alive five years down the road were 5% or sometimes less.

“Now as we look at these data we see that when appropriately treated about one in four of them are going to be around five years from now. And that completely changes our mindset.”

Dr Graham added that the findings also highlighted the importance of doing good quality prospective studies as the benefit in these sub groups of patients would not have been apparent from observational studies.

The study received funding from Merck Sharpe & Dohme.