ASCO: Forget lung cancer history. Merck's Keytruda shatters the stats on long-term survival

CHICAGO—Before the dawn of immunotherapy, long-term survival was almost a foreign concept in the metastatic lung cancer arena. But Saturday, that’s just what Merck showed Keytruda could produce.

At the American Society of Clinical Oncology (ASCO) annual meeting, the New Jersey drugmaker trotted out results showing that 23.2% of previously untreated non-small cell lung cancer (NSCLC) patients taking Keytruda were still alive at the five-year mark.

That’s far beyond the figures the field has seen historically, according to Scot Ebbinghaus, M.D., vice president of clinical research at Merck Research Laboratories. The results “signify movement of the needle for lung cancer patients treated with” Keytruda monotherapy, he said.

“It was very uncommon to see five-year survival prior to the current era of treatment,” he said, adding that “five-year survival for lung cancer has been steady, at least since I was in my oncology fellowship, at about 5%.”

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Keytruda was the first in its class of PD-1/PD-L1 cancer-fighters to win an FDA nod in frontline NSCLC, considered the largest sales opportunity for the class, and it's still the only member to boast a solo approval in the indication. Merck followed up with a chemo-combo approval, which doctors have gravitated toward, given the pairing’s success in tumors bearing various levels of the biomarker PD-L1.

On the flip side, it was high PD-L1 expressers that drove solo Keytruda’s survival benefit in a closely watched phase 3 study that rolled out at last year’s ASCO meeting. They pulled up the five-year figures as well: 29.6% of patients with tumor proportion scores of 50% or greater lived to the five-year benchmark, compared with just 15.7% of patients with PD-L1 levels below 50%.

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That finding also held true among the previously treated patients. Twenty-five percent of patients with PD-L1 levels of 50% or higher made it to the five-year target, compared with 12.6% of those with expression levels between 1% and 49%. Just 3.5% of patients with expression levels below 1% were alive after five years.

Still, Credit Suisse analyst Vamil Divan predicted the data would please investors and help "overcome some of the questions we receive ... around how long patients should remain on therapy," he wrote to clients over the weekend, noting that "some experts have previously wondered" whether PD-1/PD-L1 inhibitors "could potentially be stopped after 6 or 12 months."

"The data also bodes well for Merck’s ability to gain traction with payers," he added, "including those outside of the U.S. who may look for more longer-term outcomes data to fully support a product."