Keytruda’s KEYNOTE-189 trial marked a watershed moment in the history of lung cancer drug development by showing a monster survival benefit. Now, Merck & Co. is giving a five-year look at the data that made the PD-1 inhibitor the standard of care in newly diagnosed patients.

After five years of Keytruda and chemotherapy, an estimated 19.4% of patients with newly diagnosed metastatic nonsquamous non-small cell lung cancer (NSCLC) were alive, versus 11.3% of those who received chemotherapy alone.

“Bear in mind that typically we’re thinking of five-year survival in this population of patients is on the order of around 5% from the era of just chemotherapy treatment,” Greg Lubiniecki, M.D., vice president of clinical research at Merck Research Laboratories, said in an interview ahead of a presentation of the updated KEYNOTE-189 data at the European Society of Medical Oncology (ESMO) annual meeting.

The five-year survival rate in KEYNOTE-189’s chemo control group appeared better than historical experience partly because the patients were allowed to receive Keytruda monotherapy after disease progression on their front-line treatment, Lubiniecki noted. But it’s still no match to the Keytruda-chemo combo group, which stressed the benefit of receiving Keytruda upfront in the first-line setting, he added.

Back in 2018, KEYNOTE-189 shook the cancer community by showing that the addition of Keytruda to chemo could cut the risk of death by 51%. Thanks to that huge showing—and trial setbacks by competitors—Keytruda quickly established itself as the standard of care in newly diagnosed NSCLC.

Now, after a median 64.6 months of follow-up, the risk reduction remained strong at 40%, as patients on Keytruda and chemo lived a median 22 months—more than double the median 10.6 months that the chemo group experienced.

At the ESMO 2022 meeting, Merck also provided a five-year update from the KEYNOTE-407 trial, which has been supporting Keytruda’s use alongside chemo in newly diagnosed squamous NSCLC.