# Iomab-B

Source: https://onco.cc/drugs/iomab-b/  
OnCo record `iomab-b` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Iomab-B is Actinium's radioactive antibody that clears the bone marrow before a transplant for older patients with active relapsed acute myeloid leukaemia; the phase 3 SIERRA trial met its primary endpoint but the FDA asked for another study.

## Summary

Iomab-B delivers iodine-131 to CD45-positive cells, allowing patients with relapsed or refractory acute myeloid leukaemia who would not tolerate conventional myeloablative conditioning to proceed to allogeneic transplant. In the phase 3 SIERRA trial, Iomab-B followed by transplant produced durable complete remission at six months in a substantially higher share of patients than conventional care. Actinium reported in 2024 that the FDA requested an additional randomised trial before filing, and it is seeking partners; the trial is recorded here.

## Fields

- Kind: Treatment
- Status: phase-3
- Last checked: 2026-09-16
- Also known as: Apamistamab-I131; 131I-apamistamab
- Tags: pipeline; ctgov-ingest
- Modality: Radioimmunotherapy conditioning agent (anti-CD45 antibody labelled with iodine-131)
- Mechanism: An antibody against CD45, found on all white blood cells, carries iodine-131 to the marrow and leukaemia cells and ablates them in place of high-dose chemotherapy before a stem cell transplant.

## Sources

- ClinicalTrials.gov: trials of Iomab-B: https://clinicaltrials.gov/search?intr=Iomab-B

## Connected records

- cancers: [Acute myeloid leukaemia](https://onco.cc/cancers/aml/)
- technologies: [Radio-antibody & radio-ADC](https://onco.cc/technologies/radioimmunotherapy/), [Radioligand therapy (beta emitters)](https://onco.cc/technologies/radioligand-therapy/)
- trials: [Study of Iomab-B vs. Conventional Care in Older Subjects With Active, Relapsed or Refractory Acute Myeloid Leukemia](https://onco.cc/trials/nct02665065/)

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