# CD22

Source: https://onco.cc/targets/cd22/  
OnCo record `cd22` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

CD22 is a B-cell surface protein and the docking site for the leukaemia ADC inotuzumab ozogamicin.

## Summary

CD22 is expressed on >90% of B-ALL blasts and on B-cell lymphomas. Inotuzumab ozogamicin (INO-VATE) is approved in relapsed/refractory B-ALL and is moving into frontline for older adults (ALLIANCE A041501) and children (COG AALL1732). CD22 CAR-T (including CD19/CD22 bispecific CARs) targets CD19-negative relapse. Antigen density, not just positivity, predicts CAR-T response.

## Fields

- Kind: Target
- Last checked: 2026-09-07
- Tags: adc-target; car-t-target
- Symbol: CD22
- Class: surface-antigen
- Biology: Siglec-2; inhibitory co-receptor of the B-cell receptor, rapidly internalising, which suits ADC delivery.
- Where found: B-ALL (>90%); B-cell lymphomas; Hairy cell leukaemia

## Notes

- Lymphoma: More than 90% of B-cell acute lymphoblastic leukaemia and most B-cell non-Hodgkin lymphomas; hairy cell leukaemia carries it strongly. Also on healthy cells: Normal mature B cells; the Human Protein Atlas reads CD22 as lineage enriched in B cells (121 nTPM) and tissue enhanced in lymphoid tissue and ovary. What the medicine does: CD22 is an inhibitory co-receptor of the B-cell receptor that recycles rapidly between the surface and the endosome, which suits conjugate delivery; inotuzumab ozogamicin is the licensed example, in acute lymphoblastic leukaemia rather than in lymphoma. In lymphoma CD22 is mainly a second address after CD19 CAR-T fails. How tumours lose it: Density matters more than presence: after CD22-directed treatment, relapses often keep the antigen but at a lower surface density than the construct needs. What that costs the patient: B-cell depletion again, and for the calicheamicin conjugate hepatic sinusoidal obstruction syndrome, which is why it is used cautiously before a transplant.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/CD22
- Wikipedia: https://en.wikipedia.org/wiki/CD22
- Davis et al., Nature 2010: chronic active B-cell receptor signalling in diffuse large B-cell lymphoma: https://doi.org/10.1038/nature08638

## Connected records

- biomarkers: [CD22 expression (CD22-positive)](https://onco.cc/biomarkers/cd22-expression/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Diffuse large B-cell lymphoma](https://onco.cc/cancers/dlbcl/), [Hairy cell leukaemia](https://onco.cc/cancers/hairy-cell-leukemia/), [High-risk acute lymphoblastic leukaemia in children (high-risk B-ALL and T-ALL)](https://onco.cc/cancers/all-paediatric-high-risk/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/), [Relapsed and refractory acute lymphoblastic leukaemia in children](https://onco.cc/cancers/all-paediatric-relapsed/)
- drugs: [AZD4512](https://onco.cc/drugs/azd4512/), [Inotuzumab ozogamicin](https://onco.cc/drugs/inotuzumab-ozogamicin/), [Moxetumomab pasudotox](https://onco.cc/drugs/moxetumomab-pasudotox/), [UCART22](https://onco.cc/drugs/ucart22/)
- trials: [INO-VATE ALL](https://onco.cc/trials/ino-vate/)
- terms: [Antigen escape: how a lymphoma loses the thing the drug was aimed at](https://onco.cc/terms/lymphoma-bio-antigen-escape/), [What it costs to aim at a lineage antigen](https://onco.cc/terms/lymphoma-bio-lineage-antigen-cost/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/)
- people: [Nirali N. Shah](https://onco.cc/people/nirali-shah/)
- key papers: [INO-VATE: inotuzumab ozogamicin, a CD22 antibody-drug conjugate, versus chemotherapy for relapsed adult B-cell ALL](https://onco.cc/key-papers/paper-ino-vate-inotuzumab-all-nejm-2016/)
- institutions: [NCI Center for Cancer Research (intramural programme)](https://onco.cc/institutions/nci-ccr/)

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