An experimental antibody treatment reduced viral load in some COVID-19 patients. That may also be a positive sign for vaccines

Promising new clinical data for an experimental COVID-19 treatment hints at a secondary but possibly more important takeaway for investors: if this neutralizing antibody treatment works in coronavirus patients, so will the vaccines that are in development.

Regeneron Pharmaceuticals Inc. REGN, +1.49% on Tuesday shared preliminary data from a Phase 1/2/3 clinical trial for REGN-COV2, finding that the investigational therapy reduced viral load and made symptoms go away sooner in some non-hospitalized patients with mild or moderate cases of COVID-19. It was most effective in patients with higher viral loads who had not tested positive for antibodies. Regeneron’s stock was up 0.1% in Thursday trade.

“We believe our data will have positive implications for the likelihood of success of vaccines that target the same spike protein that REGN-COV2 targets,” Regeneron CEO Leonard Schleifer told investors on Tuesday, according to a FactSet transcript of the call.

Of the different types of therapies being tested as COVID-19 treatments, at least two are what is called neutralizing antibody cocktails. Along with Regeneron’s candidate, Eli Lilly & Co. LLY, -2.52% is also developing one, called LY-CoV555 and produced using the plasma of people who have recovered from COVID-19 infections. In mid-September, the drugmaker released promising interim data from a Phase 2 trial for LY-CoV555.