Two antibody therapies for Ebola have performed well in a late-stage clinical trial being conducted during the Ebola outbreak in the Democratic Republic of the Congo. The study, called PALM (an abbreviation for a Swahili phrase meaning “together save lives”) was testing Regeneron’s REGN-EB3, a collection of three fully human monoclonal antibodies; Ridgeback Biotherapeutics single monoclonal antibody mAb114; the nucleotide-analog antiviral remdesivir, developed by Gilead Sciences; and Mapp Biopharmaceutical’s ZMapp, a cocktail of monoclonal antibodies against Ebola glycoproteins. ZMapp, the only candidate drug previously studied in Ebola patients, was being used as the control arm in PALM because it showed a favorable survival trend in an earlier trial. Following an August review, an independent data and safety monitoring board (DSMB) stopped the trial of the four therapies, recommending that participants now be randomized to receive only REGN-EB3 or mAb114. The preliminary PALM data showed a 29% mortality rate for participants treated with REGN-EB3 and 34% with mAb114, versus 53% with remdesivir and 49% with ZMapp.

“It was clear to the DSMB that those agents are more effective than the other two,” NIAID director Anthony Fauci said in an audio briefing. “Today, we have taken new steps. From now on, we will no longer say that EBOV is not curable,” added PALM principal investigator Jean-Jacques Muyembe-Tamfum.

A week before the PALM trial announcement, the Sabin Vaccine Institute licensed rights to three vaccine candidates, including a phase 2 vaccine against Ebola, from GlaxoSmithKline.