# CD47 and SIRP-alpha blockade

Source: https://onco.cc/technologies/cd47-blockade/  
OnCo record `cd47-blockade` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Drugs that remove the 'don't eat me' signal cancer cells show to macrophages, so the immune system's scavenger cells can engulf them; the lead programme was halted for safety.

## Summary

CD47 on tumour cells binds SIRP-alpha on macrophages and stops them engulfing the cell. Antibodies and fusion proteins that block the axis (magrolimab, evorpacept and others) boost antibody-dependent phagocytosis, especially with rituximab or azacitidine. Magrolimab's phase 3 programme in myelodysplastic syndromes and acute myeloid leukaemia was stopped in 2024 after excess deaths, but SIRP-alpha-directed agents and bispecifics continue in lymphoma and solid tumours.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-09-04
- Principle: Blocking CD47 or SIRP-alpha removes the inhibitory signal so macrophages phagocytose opsonised tumour cells; agents are engineered to spare red cells, which also express CD47.
- Strengths: Engages macrophages, a different arm from T-cell checkpoints; Synergy with therapeutic antibodies
- Limitations: Anaemia from red cell CD47; Magrolimab programme stopped for safety; No approval yet

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/CD47
- Wikipedia: https://en.wikipedia.org/wiki/CD47

## Connected records

- cancers: [Acute myeloid leukaemia](https://onco.cc/cancers/aml/), [Diffuse large B-cell lymphoma](https://onco.cc/cancers/dlbcl/), [Higher-risk myelodysplastic syndromes](https://onco.cc/cancers/mds-higher-risk/), [Myelodysplastic syndromes / neoplasms (MDS)](https://onco.cc/cancers/mds/), [Secondary and therapy-related acute myeloid leukaemia](https://onco.cc/cancers/aml-secondary/)
- fronts: [Immunotherapy](https://onco.cc/fronts/immunotherapy/)
- targets: [CD24](https://onco.cc/targets/cd24/), [CD47](https://onco.cc/targets/cd47/)
- drugs: [Evorpacept](https://onco.cc/drugs/evorpacept/), [Magrolimab](https://onco.cc/drugs/magrolimab/)
- technologies: [Monoclonal antibodies](https://onco.cc/technologies/monoclonal-antibody/)
- trials: [A Study of Evorpacept (ALX148) in Patients With Advanced HER2+ Gastric Cancer (ASPEN-06)](https://onco.cc/trials/aspen-06/), [ASPEN-09-03: A Study of Evorpacept in Combination With Trastuzumab and Chemotherapy in Metastatic HER2-Positive Breast Cancer](https://onco.cc/trials/nct07007559/), [Evorpacept (ALX148) in Combination With Pembrolizumab and Chemotherapy in Patients With Advanced Head and Neck Squamous Cell Carcinoma (ASPEN-04)](https://onco.cc/trials/nct04675333/), [Evorpacept (ALX148) in Combination With Pembrolizumab in Patients With Advanced Head and Neck Squamous Cell Carcinoma (ASPEN-03)](https://onco.cc/trials/nct04675294/)

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