{"entity":{"id":"cd22","kind":"target","name":"CD22","aka":[],"tldr":"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.","asOf":"2026-09-07","wikipedia":"https://en.wikipedia.org/wiki/CD22","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/CD22"},{"label":"Davis et al., Nature 2010: chronic active B-cell receptor signalling in diffuse large B-cell lymphoma","url":"https://doi.org/10.1038/nature08638"}],"tags":["adc-target","car-t-target"],"related":["cd22-expression"],"cancers":["all-leukemia","dlbcl","non-hodgkin-lymphoma"],"sections":[],"technologies":[],"targets":[],"drugs":["inotuzumab-ozogamicin","ucart22","azd4512"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"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."],"symbol":"CD22","role":[],"sources":[],"specificity":"lineage-antigen","distribution":"few-types","specificityNote":"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.)","specificitySources":[{"label":"CD22 expression (CD22-positive) label threshold","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=cc7014b1-c775-411d-b374-8113248b4077","note":"CD22-positive"},{"label":"Human Protein Atlas CD22 tissue","url":"https://www.proteinatlas.org/ENSG00000012124-CD22/tissue","note":"RNA tissue and blood lineage specificity, normal tissue antibody staining (version 25.1, CC BY-SA 3.0)"},{"label":"Human Protein Atlas CD22 pathology","url":"https://www.proteinatlas.org/ENSG00000012124-CD22/pathology","note":"patients per staining level per cancer type (version 25.1, CC BY-SA 3.0)"},{"label":"Open Targets ENSG00000012124 associations","url":"https://platform.opentargets.org/target/ENSG00000012124/associations","note":"cancer associations at or above 0.5 (CC0)"}],"hgnc":"HGNC:1643","ensembl":"ENSG00000012124","uniprot":"P20273","entrez":"933","firstDescribed":1990,"firstDescribedBasis":"sequence","firstDescribedNote":"Earliest sequence paper UniProt cites for the protein: Stamenkovic et al, Nature, 1990, \"The B-cell antigen CD22 mediates monocyte and erythrocyte adhesion\".","firstDescribedSource":"https://pubmed.ncbi.nlm.nih.gov/1691828/","biology":"Siglec-2; inhibitory co-receptor of the B-cell receptor, rapidly internalising, which suits ADC delivery.","whereFound":["B-ALL (>90%)","B-cell lymphomas","Hairy cell leukaemia"],"targetClass":"surface-antigen","prevalence":[{"cancerId":"all-leukemia","pct":">90","measure":"expression on B-ALL blasts"}]},"route":"/targets/cd22/","neighbours":{"biomarker":[{"id":"cd22-expression","kind":"biomarker","name":"CD22 expression (CD22-positive)","route":"/biomarkers/cd22-expression/"}],"cancer":[{"id":"all-leukemia","kind":"cancer","name":"Acute lymphoblastic leukaemia","route":"/cancers/all-leukemia/"},{"id":"dlbcl","kind":"cancer","name":"Diffuse large B-cell lymphoma","route":"/cancers/dlbcl/"},{"id":"hairy-cell-leukemia","kind":"cancer","name":"Hairy cell leukaemia","route":"/cancers/hairy-cell-leukemia/"},{"id":"all-paediatric-high-risk","kind":"cancer","name":"High-risk acute lymphoblastic leukaemia in children (high-risk B-ALL and T-ALL)","route":"/cancers/all-paediatric-high-risk/"},{"id":"non-hodgkin-lymphoma","kind":"cancer","name":"Non-Hodgkin lymphoma (all types)","route":"/cancers/non-hodgkin-lymphoma/"},{"id":"all-paediatric-relapsed","kind":"cancer","name":"Relapsed and refractory acute lymphoblastic leukaemia in children","route":"/cancers/all-paediatric-relapsed/"}],"drug":[{"id":"azd4512","kind":"drug","name":"AZD4512","route":"/drugs/azd4512/"},{"id":"inotuzumab-ozogamicin","kind":"drug","name":"Inotuzumab ozogamicin","route":"/drugs/inotuzumab-ozogamicin/"},{"id":"moxetumomab-pasudotox","kind":"drug","name":"Moxetumomab pasudotox","route":"/drugs/moxetumomab-pasudotox/"},{"id":"ucart22","kind":"drug","name":"UCART22","route":"/drugs/ucart22/"}],"trial":[{"id":"ino-vate","kind":"trial","name":"INO-VATE ALL","route":"/trials/ino-vate/"}],"term":[{"id":"lymphoma-bio-antigen-escape","kind":"term","name":"Antigen escape: how a lymphoma loses the thing the drug was aimed at","route":"/terms/lymphoma-bio-antigen-escape/"},{"id":"lymphoma-bio-lineage-antigen-cost","kind":"term","name":"What it costs to aim at a lineage antigen","route":"/terms/lymphoma-bio-lineage-antigen-cost/"}],"technology":[{"id":"adc","kind":"technology","name":"Antibody-drug conjugate (ADC)","route":"/technologies/adc/"}],"person":[{"id":"nirali-shah","kind":"person","name":"Nirali N. Shah","route":"/people/nirali-shah/"}],"paper":[{"id":"paper-ino-vate-inotuzumab-all-nejm-2016","kind":"paper","name":"INO-VATE: inotuzumab ozogamicin, a CD22 antibody-drug conjugate, versus chemotherapy for relapsed adult B-cell ALL","route":"/key-papers/paper-ino-vate-inotuzumab-all-nejm-2016/"}],"institution":[{"id":"nci-ccr","kind":"institution","name":"NCI Center for Cancer Research (intramural programme)","route":"/institutions/nci-ccr/"}]}}