CD22 expression (CD22-positive)

aka CD22-positive, CD22+, CD22 expression, CD22 positive ALL

CD22 is a second B-cell antigen, kept even when CD19 is lost. Inotuzumab ozogamicin is labelled for CD22-positive acute lymphoblastic leukaemia.

CD22 is measured by flow cytometry on blasts; more than 90 percent of B-ALL is CD22-positive. Inotuzumab ozogamicin (Besponsa) is a CD22-directed antibody-drug conjugate labelled for relapsed or refractory CD22-positive B-cell precursor ALL in adults and children aged one and over. CD22-directed CAR-T cells are in trials for CD19-negative relapse after blinatumomab or CD19 CAR-T.

Part ofCD22· CD22 All readouts

CD22: what it is and how drugs act on it · animated schematic, not to scale

Target · the protein and the cell it sits on
Drug · antibody, small molecule, cell or radioligand
Effect · signal, damage or kill

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

IHC score 1 approval threshold

What it means for a patient

If your leukaemia is CD22-positive, inotuzumab ozogamicin is an on-label option when the disease has come back or not responded, and it remains usable if CD19 has been lost after blinatumomab or CAR-T. Liver toxicity, especially before a transplant, is the main thing your team will weigh.

Written only from the label or guideline text cited on this page. Not medical advice; your own report and the reading your team gives it come first.

Scoring rule

CD22 detected on leukaemia blasts by flow cytometry; the label states CD22-positive without a percentage.

“BESPONSA is a CD22-directed antibody and cytotoxic drug conjugate”
Besponsa prescribing information

Thresholds used in approvals

Threshold	Drug	Cancer	Regulator	Source
CD22-positive Besponsa indication: relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukemia in adults and pediatric patients 1 year and older.	Inotuzumab ozogamicin	Acute lymphoblastic leukaemia	FDA	label

Drugs whose label names it

Inotuzumab ozogamicin

Trials that name this readout

Matched on the name and aliases of the readout in the title, setting and summary of each trial; a match is a mention, not proof the readout was an entry criterion.