Ebanga (ansuvimab, mAb114) is a single monoclonal antibody against Zaire ebolavirus, FDA-approved December 2020 and developed by Ridgeback Biotherapeutics. Inmazeb is a triple-antibody cocktail (three components) from Regeneron, approved October 2020. Both target Zaire ebolavirus specifically, performed similarly in the PALM trial, and are inapplicable to Bundibugyo.Source: FDA approvals; PALM trial results

Where did the Ebanga antibody come from?

Ebanga was derived from the blood of a survivor of the 1995 Kikwit Zaire ebolavirus outbreak in DRC. Researchers isolated and characterised the human antibody before manufacturing it at scale. It was trialled in DRC communities during the 2018-20 Kivu Ebola epidemic.Source: FDA approval documentation; PALM trial publications

Why aren't Ebola treatments from 2018 being used in 2026?

Both Ebanga and Inmazeb are FDA-approved for Zaire ebolavirus only. The 2026 outbreak is caused by Bundibugyo ebolavirus, a different species with a different glycoprotein that these antibodies do not effectively bind. No cross-protection data has been established or approved. Clinicians in Ituri can legally and medically only use supportive care.Source: FDA labels; Imperial College London; PMC10032372

Background

Ebanga is a single monoclonal antibody (ansuvimab, also known as mAb114) developed by Ridgeback Biotherapeutics and approved by the FDA in December 2020. Unlike Inmazeb's triple-antibody approach, Ebanga relies on a single broad-spectrum antibody derived from the blood of a survivor of the 1995 Kikwit Zaire Ebola outbreak — a human antibody that was isolated, characterised and then manufactured at scale. The antibody binds to a conserved receptor-binding site on the Zaire ebolavirus glycoprotein, blocking viral attachment to host cells.

Ebanga was also evaluated in the PALM trial during the 2018-20 DRC Kivu outbreak. Its PALM trial survival rate was similar to Inmazeb's — both significantly outperformed ZMapp — and both were recommended by WHO as preferred treatments for Zaire ebolavirus disease. The fact that the antibody originates from a Congolese survivor's blood, and was then trialled predominantly in DRC communities, is historically significant and was central to early debates about equitable access to any resulting approved product.

Ridgeback Biotherapeutics is a smaller US biopharmaceutical company focused on antiviral and antibacterial development. It is also the original developer of molnupiravir (COVID-19 antiviral), licensed to Merck. The company holds US government supply agreements for Ebanga as a biodefence medical countermeasure.

Like Inmazeb, Ebanga cannot be used in the 2026 Bundibugyo Ebola outbreak because its FDA approval and clinical-efficacy data are specific to Zaire ebolavirus. The antibody's binding site on the Zaire glycoprotein does not have a structurally equivalent target on the Bundibugyo glycoprotein, and no cross-protection data has been established in clinical trials or approved by regulators.

The WHO WATCH FOR section of the 17 May PHEIC briefing explicitly flags whether Ridgeback Biotherapeutics publishes cross-reactivity data for Ebanga against Bundibugyo. Craig Spencer noted at the 15 May specialist panel that ribavirin from the PALM trial — not Ebanga or Inmazeb — is the only candidate therapeutic with any cross-Ebola signal worth attempting under Bundibugyo conditions, provided laboratory monitoring of hepatic function is possible.

The practical consequence: frontline clinicians in Bunia and Mongbwalu have no approved therapeutic equivalent to what MSF and CDC teams had available in the 2018 Equateur response. The Ebanga and Inmazeb supply that reduced the Equateur outbreak to 54 cases and 33 deaths in three months is present in strategic stockpiles but legally and medically inapplicable to the current strain.

Source Material

Therapeutic monoclonal antibodies against Ebola virus species and the filovirus class

How the World Sees Them

WHO

Ebanga and Inmazeb are both preferred treatments for Zaire ebolavirus per WHO recommendations; neither is recommended for Bundibugyo because no data exists.

Frontline clinicians

Ribavirin from the PALM trial is cited as the only candidate with any cross-Ebola signal; Ebanga and Inmazeb are categorically excluded.

Ridgeback Biotherapeutics

No public statement on Bundibugyo cross-reactivity as of 17 May; the WATCH FOR item for this outbreak is whether the company will release such data.

DRC / community equity lens (Craig Spencer)

Ebanga's Congolese origin — derived from a Kikwit survivor's blood, trialled in DRC communities — makes its inapplicability to a DRC Bundibugyo outbreak an additional equity dimension: the product derived from DRC's suffering cannot be used for DRC's current outbreak.