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CD22 is a B-cell surface protein and the docking site for the leukaemia ADC inotuzumab ozogamicin.
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.
In plain words · CD22 is a B-cell surface protein and the docking site for the leukaemia ADC inotuzumab ozogamicin.
CD22 is a B-cell surface protein and the docking site for the leukaemia ADC inotuzumab ozogamicin.
Siglec-2; inhibitory co-receptor of the B-cell receptor, rapidly internalising, which suits ADC delivery.
4 products aim at CD22: antibody-drug conjugates, cell therapies and immunotoxins. Because it sits on the outside of the cell, it can be reached from the bloodstream: antibodies flag the cell, ADCs deliver a toxin, radioligands deliver radiation, and CAR-T or bispecifics bring a T cell.
Lineage antigen shared with normal B-cells: the label readouts filed under it score its expression (CD22 expression (CD22-positive)), and HPA finds the gene lineage enriched in that blood lineage at or above 25 nTPM, so medicines aimed at it clear the normal lineage too. HPA CD22: RNA tissue enhanced (lymphoid tissue 215 nTPM, ovary 125 nTPM); blood lineage lineage enriched (B-cells 121 nTPM); high antibody staining in 2 normal tissues; highest cancer staining lymphoma (1 of 12 high). Distribution: 2 cancer families in the corpus carry a prevalence row, label threshold or catalogue link for it (Leukaemia, Lymphoma); Open Targets associates it with 2 specific cancer types at or above 0.5 (acute lymphoblastic leukemia, hairy cell leukemia). (Rule 3 of scripts/fetch-target-specificity.ts.)
Sources: CD22 expression (CD22-positive) label threshold; Human Protein Atlas CD22 tissue; Human Protein Atlas CD22 pathology; Open Targets ENSG00000012124 associations
First described 1990. Earliest sequence paper UniProt cites for the protein: Stamenkovic et al, Nature, 1990, "The B-cell antigen CD22 mediates monocyte and erythrocyte adhesion". Source.
What a pathology or genomic report can say about this target, each with the thresholds approvals use.
Siglec-2; inhibitory co-receptor of the B-cell receptor, rapidly internalising, which suits ADC delivery.
RNA: tissue enhanced (lymphoid tissue 215 nTPM, ovary 125 nTPM), detected in many normal tissues. Blood: lineage enriched (B-cells 121 nTPM).
Medium: Appendix, Lymph node, Testis.
HPA CD22 tissue · HPA CD22 pathology · HPA protein class: CD markers, FDA approved drug targets
Human Protein Atlas version 25.1, antibody staining at reliability approved, enhanced or supported; used under CC BY-SA 3.0. Staining counts are patients per level in the atlas cohort, not population prevalence.
| Cancer | Prevalence | Measure | Note | Source |
|---|---|---|---|---|
| Acute lymphoblastic leukaemia | >90% | expression on B-ALL blasts |
Approximate, population-level figures; the measure column says what was counted. Ranges show the midpoint as a bar.
AZD4512 is an experimental antibody-drug conjugate from AstraZeneca in phase 2 trials for hodgkin lymphoma, aimed at CD22.
Inotuzumab ozogamicin is an antibody carrying a DNA-cutting toxin to CD22 on leukaemia cells. It gets far more relapsed ALL patients into remission than chemotherapy and bridges them to transplant.
An immunotoxin for hairy cell leukaemia that produced lasting remissions in relapsed patients but was withdrawn from sale in 2023 for commercial reasons.
UCART22 is an experimental allogeneic CAR T-cell therapy from Cellectis S.A. in phase 2 trials for acute lymphoblastic leukaemia, aimed at CD22.
Query for this target: (TITLE:"CD22" OR ABSTRACT:"CD22") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about CD22, not a curated reading list.
Shares NCI Center for Cancer Research (intramural programme) and the tags adc-target, car-t-target.
Shares Antibody-drug conjugate (ADC) and the tags adc-target, car-t-target.
Shares Hairy cell leukaemia, Antibody-drug conjugate (ADC) and the tag adc-target.
Shares Antigen escape: how a lymphoma loses the thing the drug was aimed at, Antibody-drug conjugate (ADC), Diffuse large B-cell lymphoma, Non-Hodgkin lymphoma (all types) and the tag adc-target.
Shares Antibody-drug conjugate (ADC), Diffuse large B-cell lymphoma and the tag adc-target.
Shares Nirali N. Shah, Antigen escape: how a lymphoma loses the thing the drug was aimed at, What it costs to aim at a lineage antigen, High-risk acute lymphoblastic leukaemia in children (high-risk B-ALL and T-ALL) and the tag car-t-target.
Shares Antibody-drug conjugate (ADC) and the tag adc-target.
Shares Antibody-drug conjugate (ADC) and the tag adc-target.