Study Design
DesignRandomized, open-label, active-controlled, multi-arm (adaptive), conducted during DRC Ebola outbreak
Randomization1:1:1:1
BlindingOpen-label (emergency outbreak setting)
Enrollment681
Duration4 weeks
Treatment Arms
REGN-EB3 (Inmazeb) Triple mAb cocktail, single IV infusion n=174
MAb114 (ansuvimab) Single mAb, single IV infusion n=174
ZMapp (control) Triple mAb cocktail IV (3 infusions over 9 days) n=169
Remdesivir IV infusion daily x 10 days n=164
[{"id":"palm-mortality","name":"28-day mortality","type":"PRIMARY","unit":"%","results":[{"notes":"33.5% 28-day mortality (58/174)","value":33.5,"arm_id":"regn-eb3-palm","arm_name":"REGN-EB3 (Inmazeb)"},{"value":35.1,"arm_id":"mab114-palm","arm_name":"MAb114"},{"notes":"Control arm: 51.3% mortality","value":51.3,"arm_id":"zmapp-palm","arm_name":"ZMapp (control)"},{"value":53.1,"arm_id":"remdesivir-palm","arm_name":"Remdesivir"}],"timepoint":"Day 28","description":"Death from any cause within 28 days of treatment initiation. Lower is better. Conducted during an active Ebola outbreak in the Democratic Republic of Congo."}]
PALM showed REGN-EB3 (33.5% mortality) and MAb114 (35.1%) were superior to ZMapp (51.3%) and remdesivir (53.1%). The DSMB stopped enrollment early due to clear superiority. In low viral load patients, REGN-EB3 mortality was only 9.9% vs 33% ZMapp.
PALM (n=681, Ebola outbreak): Safety assessment limited by severe underlying disease. Hypotension 3%, fever 7% with REGN-EB3. AEs difficult to distinguish from Ebola disease course. Single-infusion REGN-EB3 simpler than 3-infusion ZMapp.
PALM was a landmark trial — conducted DURING a lethal Ebola outbreak in the DRC. Stopped early because REGN-EB3 clearly saved lives (34% vs 51% mortality). The low viral load subgroup (9.9% mortality) shows early treatment is critical. Commercially small but strategically important for REGN reputation and government contracts.