Sanofi, Regeneron take aim at Keytruda with Libtayo's first lung cancer win

Libtayo bottle and box
Sanofi and Regeneron's Libtayo beat chemotherapy at extending patients' lives in newly diagnosed non-small cell lung cancer, kicking off a potential fight against Merck & Co.'s market-leading Keytruda. (Sanofi and Regeneron)

Sanofi and Regeneron may be late to the PD-1/PD-L1 party with sixth-to-market Libtayo, but they sure don’t intend to miss out on the lucrative lung cancer market. And with just-released data, they're on their way to a chance to wrest share away from Merck's leader, Keytruda.

A phase 3 trial comparing solo Libtayo against platinum chemotherapy in newly diagnosed non-small cell lung cancer showed the drug could extend patients' lives, the partners said Monday. Among patients whose tumors bore levels of biomarker PD-L1 of at least 50%, Libtayo cut the risk of death by 32.4%.

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That kind of survival showing could put some pressure on Merck’s Keytruda, now the clear class leader. In its own phase 3 monotherapy study, Keynote-042, Keytruda alone reduced the risk of death by 31% in those with PD-L1 expression levels of at least 50%—the same population studied in the Libtayo trial.

The thing is, most patients these days don't get monotherapy. Instead, they receive a combination of Keytruda and chemo, a regimen that's shown it cut patients' risk of death in half, regardless of PD-L1 status. That combo is responsible for the lion's share of Keytruda's $11.1 billion in 2019 sales, while solo Keytruda is reserved for those who can't tolerate chemo.

And Sanofi and Regeneron aren't the only ones trying to tread on Keytruda's monotherapy turf. Roche’s Tecentriq is also close to a nod in the front-line, PD-L1-high monotherapy realm, with the FDA set to rule by June 19—meaning if the pair can score a green light for Libtayo, they'll have to go up against the Swiss drugmaker, too. In the IMpower110 study, Tecentriq improved prolonged patients’ lives by an additional 7.1 months compared with chemo, cutting patients' risk of death by about 40%.

RELATED: Roche's solo Tecentriq advances toward Keytruda showdown with 'priority' boost in lung cancer

Sanofi and Regeneron have kept more detailed results under wrap so far, and cross-trial data comparisons can be problematic given different trial designs and specific patient profiles. But Sanofi R&D head John Reed was quick to point out that his company's is the largest clinical trial evaluating a PD-1 inhibitor as a first-line monotherapy in NSCLC with high PD-L1 expression, calling the results “extremely encouraging.” NSCLC accounts for about 85% of all lung cancer cases, with about 25% to 30% of patients expressing PD-L1 levels at or above 50%.

Buoyed by the results, Sanofi and Regeneron now plan to submit the current data for U.S. and European approvals in 2020, and they've modified the trial to allow all patients, including those in the chemo control arm, to receive Libtayo. Separately, a clinical trial is testing the Libtayo-chemo combo in first-line patients regardless of PD-L1 expression.

But meanwhile, Piper Sandler analyst Christopher Raymond has forecast "just 4% U.S. patient share in 1L NSCLC," he wrote in a Monday note to clients, adding that combined with the Sanofi and Regeneron drug's current indication in cutaneous squamous cell carcinoma, the drug could pull in $1.5 billion in worldwide revenue.

Editor's Note: A previous version of the story mistakenly stated that the Libtayo monotherapy trial has been modified to include all patients regardlss of PD-L1 expression. It's actually been changed to allow patients in the control arm to now receive Libtayo.