Monday was an awfully big day for Regeneron (NASDAQ:REGN) and its collaboration partner, Sanofi (NASDAQ:SNY). The biopharmaceuticals reported successful results from a clinical trial with lung cancer patients, and negative results from a different study with COVID-19 patients. 

Kevzara disappoints 

Preliminary results from a clinical trial of Kevzara in severe-to-critical COVID-19 patients were not quite what the companies had hoped for.

Kevzara, a rheumatoid arthritis treatment, dials down the immune system, which is usually a terrible idea for patients trying to fight off an infection. But in some people, COVID-19 can whip the immune system into a lethal frenzy -- a response called a cytokine storm. Last month, studies were initiated to see whether Kevzara could provide those patients with a survival benefit.

Person in lab with a flask of purple stuff

Image source: Getty Images.

An independent data monitoring committee compared results from patients receiving Kevzara and those receiving a placebo, and found that among those with severe cases of COVID-19 -- as opposed to the even more at-risk "critical" group -- the outcomes were about the same.

"Severe" was defined as requiring some oxygen, but not ventilation. Approximately 80% of those patients were discharged, 10% succumbed to their illness, and 10% remain hospitalized. But given that Kevzara proved no better than a placebo for that group, the committee recommended the trial continue with only critical patients -- those who required either ventilators, high-flow oxygenation, or treatment in an intensive care unit.

Libtayo gets it done

Libtayo is a drug from Regeneron and Sanofi that works along the same pathway as Keytruda, a highly successful immunotherapy from Merck (NYSE:MRK). Independent data monitors with an eye on lung cancer patients receiving either Libtayo or standard chemotherapy halted a late-stage clinical trial early so everyone in the control group could switch over and receive Libtayo, which was demonstrating a clear survival benefit.

Libtayo as a monotherapy reduced patients' risk of death by 32% compared to standard chemotherapy for patients with tumors that tested positive for PD-L1 on at least half of their cells. These results are impressive, and will most likely lead to a label expansion and billions in additional revenue each year for Sanofi and Regeneron.