A clinical trial with thousands of hospitalized coronavirus patients failed to hit the mark for the last time on Thursday. A group of COVID-19 patients requiring mechanical ventilation failed to show measurable improvement when treated in a phase 3 trial with Kevzara from Regeneron (REGN -0.67%). In June, Regeneron reported Kevzara's failure to provide a benefit for hospitalized COVID-19 patients severe enough to require oxygen, but not severe enough to require mechanical ventilation.

Worth a shot 

In patients with severe COVID-19 infections, it isn't unusual to see overexcited immune systems do more harm than good. Earlier this year, investigators in China noticed lots of unhelpful immune processes in the lungs initiated by a protein called interleukin-6 (IL-6), and Kevzara seemed like a good fit to address this.

Person in lab writing on clipboard

Image source: Getty Images.

Kevzara is a drug Regeneron markets in partnership with Sanofi (SNY 1.22%) that helps rheumatoid arthritis patients by preventing a protein called interleukin-6 (IL-6) from attacking healthy joints. The trial results showed a minor positive trend that suggested a benefit for patients who required mechanical ventilation when they began treatment, but the trend wasn't strong enough to be considered statistically significant.

In June, investigators from Britain's National Health Service (NHS) reported positive results from a study with over 11,500 enrolled patients who were treated with a decades-old steroid that costs pennies per tablet, dexamethasone. Treatment with the generic steroid reduced patients' risk of death by 35% compared to standard care without dexamethasone.

Regeneron's rheumatoid arthritis gamble flopped, but REGN-COV2, a combination of antibodies that attach to SARS-CoV-2, the virus that causes COVID-19, still has a chance. Investigators began treating COVID-19 patients with Regeneron's REGN-COV2 last month, making it the first antibody-based candidate that uses a pair of proteins to stop SARS-CoV-2 from entering host cells to reach this stage.