CD20 expression (CD20-positive)

aka CD20-positive, CD20+, CD20 expression, CD20 positive lymphoma, CD20 loss

CD20 is the B-cell antigen rituximab made famous. Rituximab and obinutuzumab labels are written for CD20-positive lymphoma and leukaemia; the newer CD20 x CD3 bispecifics assume it.

CD20 is read by immunohistochemistry or flow cytometry and is present on almost all mature B-cell lymphomas and chronic lymphocytic leukaemia. Rituximab (Rituxan) is labelled as a CD20-directed cytolytic antibody for CD20-positive non-Hodgkin lymphoma and CLL; obinutuzumab (Gazyva) for CLL and follicular lymphoma; mosunetuzumab, glofitamab and epcoritamab are CD20 x CD3 bispecifics labelled by histology. CD20-negative lymphomas (some after rituximab, and entities such as plasmablastic lymphoma) are excluded from the anti-CD20 indications.

Part ofCD20· MS4A1 All readouts

CD20: 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 · CD20 is a B-cell marker; rituximab against it was the first antibody approved for cancer, in 1997.

IHC score 1 approval threshold

What it means for a patient

A CD20-positive result is expected in nearly every B-cell lymphoma and means rituximab or obinutuzumab will be part of treatment, with the CD20-directed bispecific antibodies as later options. A CD20-negative result, which can happen after previous rituximab, steers the team to drugs aimed at other targets.

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

CD20 detected on lymphoma or leukaemia cells by immunohistochemistry or flow cytometry; the labels state CD20-positive without a percentage.

“RITUXAN is a CD20-directed cytolytic antibody indicated for the treatment of: Adult patients with Non-Hodgkin's Lymphoma (NHL)”
Rituxan prescribing information

Thresholds used in approvals

Threshold	Drug	Cancer	Regulator	Source
CD20-positive The full indication text specifies CD20-positive follicular, low-grade and diffuse large B-cell lymphoma and CD20-positive CLL.	Rituximab	Non-Hodgkin lymphoma (all types)	FDA	label

Drugs whose label names it

Rituximab

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.