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Protein / target

B-lymphocyte antigen CD20

Encoded byMS4A1P11836Homo sapiensSwiss-Prot
Clinically validated
Therapeutic maturity
11
Approved medicines
Open Targets target-level
View by indication →
30
Clinical trials
Small-molecule tractable
Druggability
Structure with Ligand

Protein at a glance

Biological role

Epidermal growth factor receptor binding

Strongest disease association

Leukemia, Lymphocytic, Chronic, B-Cell

Via encoding gene MS4A1 · Clinical evidence · score 0.63

Therapeutic position

Established drug target

Antibodies

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function overview

B-lymphocyte-specific membrane protein that plays a role in the regulation of cellular calcium influx necessary for the development, differentiation, and activation of B-lymphocytes.

View complete UniProt function annotation

B-lymphocyte-specific membrane protein that plays a role in the regulation of cellular calcium influx necessary for the development, differentiation, and activation of B-lymphocytes (PubMed:12920111, PubMed:3925015, PubMed:7684739). Functions as a store-operated calcium (SOC) channel component promoting calcium influx after activation by the B-cell receptor/BCR (PubMed:12920111, PubMed:18474602, PubMed:7684739)

Subcellular location

Cell membrane
Domains and Gene Ontology detail (20)

Gene Ontology

  • Ccell surface
  • Cexternal side of plasma membrane
  • Cextracellular exosome
  • Cextracellular space
  • Cplasma membrane
  • Cplasma membrane raft
  • Fepidermal growth factor receptor binding
  • Fidentical protein binding
  • Fimmunoglobulin binding
  • FMHC class II protein complex binding
  • PB cell activation
  • PB cell differentiation

297 aa · 33 kDa · 2 isoforms

Biological roles

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

Immune signallingGO
View supporting evidence

Immune signalling

  • ·B cell activation
  • ·B cell differentiation
  • ·B cell proliferation
  • ·B cell receptor signaling pathway

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

CD19MS4A3CD79ACD22IGKV2D…IGHV3-…POU2AF1CD79BBANK1TCL1AMS4A1

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Approved medicines with mapped indications

5 medicines · 7 areas

Approved therapies targeting this protein, grouped by what they are approved to treat — the disease-first view of the medicines below. Relationships come from the canonical approved-indication graph (ChEMBL phase-4), the same source as the drug cards.

Leukemia, Lymphocytic, Chronic, B-Cell2 medicines
Lymphoma, Follicular2 medicines
Lymphoma, Large B-Cell, Diffuse2 medicines
Multiple Sclerosis2 medicines
Multiple Sclerosis, Relapsing-Remitting2 medicines
Multiple Sclerosis, Chronic Progressive1 medicine
Broader indication categories (1)

Broad umbrella indications (e.g. “Neoplasms”). Shown here because every medicine also appears under a more specific disease above — kept for completeness, de-emphasised for clarity.

11 medicines meet Open Targets' target-level approved-medicine definition; the 5 shown here are those on this page with a canonical approved disease indication in the graph. Approved indications from ChEMBL (phase-4), via the canonical drug→disease graph.

Drugs targeting this protein

5

How approved and investigational drugs engage this protein — mechanism and action type, direct vs complex targeting, and how broadly each acts across other targets. A drug-first view (the section above groups the approved ones disease-first); direct binders with few recorded targets are listed first.

ocrelizumab
Narrow target profileApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Indicated for Multiple Sclerosis, Multiple Sclerosis, Chronic Progressive, Multiple Sclerosis, Relapsing-Remitting

Direct interaction with this protein · Only this protein recorded as a target

obinutuzumab
Narrow target profileApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Indicated for Leukemia, Lymphocytic, Chronic, B-Cell, Lymphoma, Follicular, Neoplasms

Direct interaction with this protein · Only this protein recorded as a target

ofatumumab
Narrow target profileApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Indicated for Leukemia, Lymphocytic, Chronic, B-Cell, Multiple Sclerosis, Multiple Sclerosis, Relapsing-Remitting, Neoplasms

Direct interaction with this protein · Only this protein recorded as a target

glofitamab
ApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Indicated for Lymphoma, Large B-Cell, Diffuse, Neoplasms

Direct interaction with this protein · 1 of 4 recorded protein targets

epcoritamab
ApprovedBinding agent

B-lymphocyte antigen CD20 binding agent

Indicated for Lymphoma, Follicular, Lymphoma, Large B-Cell, Diffuse, Neoplasms

Direct interaction with this protein · 1 of 4 recorded protein targets

ChEMBL mechanism, action type, target identity and approved indications. Open Targets clinical status.

Translational evidence

Open Targets 26

Why this target matters therapeutically, strongest evidence first. Disease associations are gene-level (via the gene that encodes this protein) and open into the full confidence synthesis; the development universe, tractability and safety annotations are target-level, from Open Targets.

Strongest disease associations · via encoding gene MS4A1

Gene-level evidence surfaced through the gene MS4A1 that encodes this protein — not a direct protein–disease relationship. Ranked by Forefront's causal-directness weighting, so genetically- and clinically-evidenced diseases lead over ones that merely share the literature.

Leukemia, Lymphocytic, Chronic, B-Cell
0.78Well supported

Clinical evidence dominant · Open Targets 0.63

Lymphoma, Large B-Cell, Diffuse
0.77Well supported

Clinical evidence dominant · Open Targets 0.62

Lymphoma, Follicular
0.76Well supported

Clinical evidence dominant · Open Targets 0.62

Arthritis, Rheumatoid
0.76Well supported

Clinical evidence dominant · Open Targets 0.61

Lymphoma, Non-Hodgkin's
0.76Well supported

Clinical evidence dominant · Open Targets 0.61

View evidence synthesis (5)
Leukemia, Lymphocytic, Chronic, B-CellWell supported
0.78
agreement 0.640.91
Clinical84%Literature15%RNA expression1%

Open Targets aggregate 0.63 · 3 independent evidence families

Lymphoma, Large B-Cell, DiffuseWell supported
0.77
agreement 0.610.92
Clinical85%Literature15%

Open Targets aggregate 0.62 · 2 independent evidence families

Lymphoma, FollicularWell supported
0.76
agreement 0.610.92
Clinical88%Literature12%

Open Targets aggregate 0.62 · 2 independent evidence families

Arthritis, RheumatoidWell supported
0.76
agreement 0.620.89
Clinical92%Literature8%RNA expression0%

Open Targets aggregate 0.61 · 3 independent evidence families

Lymphoma, Non-Hodgkin'sWell supported
0.76
agreement 0.600.91
Clinical92%Literature8%

Open Targets aggregate 0.61 · 2 independent evidence families

The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the per-type scores above show the calculation.

Show all associations
Leukemia, Lymphocytic, Chronic, B-Cell0.63
Lymphoma, Large B-Cell, Diffuse0.62
Lymphoma, Follicular0.62
Arthritis, Rheumatoid0.61
Lymphoma, Non-Hodgkin's0.61
Multiple Sclerosis0.61
Neoplasms0.59
Precursor Cell Lymphoblastic Leukemia-Lymphoma0.58
Granulomatosis with polyangiitis0.58
Multiple Sclerosis, Relapsing-Remitting0.57

Drug development

18 compounds recorded · 11 approved · 7 in clinical development

Open Targets' development universe — every compound recorded against the target at any stage, not all approved medicines. Distinct from the 5 drugs that target this protein in Forefront's canonical graph (5 with a mapped approved indication, shown above): these count different sets and are not a subset relation.

View all recorded compounds (10)
GLOFITAMABApproval
OBINUTUZUMABApproval
UBLITUXIMABApproval
TOSITUMOMAB 131IPhase 3
FBT-A05Phase 1 2
MT-3724Phase 2
MOSUNETUZUMABApproval
TOSITUMOMABApproval
OCARATUZUMABPhase 2
EPCORITAMABApproval

Open Targets known-drugs universe. Drug name and highest clinical stage only — the disease relationship is NOT read from this slice (it carries trial-context noise); approved indications come from the canonical graph above.

Tractability

Small moleculesEmerging

Feasibility evidence (structure with ligand) — no clinical-stage drug of this modality recorded.

AntibodiesStrong

Approved Drug and UniProt loc high conf support this modality.

Protein degradersEmerging

Feasibility evidence (database ubiquitination and half-life data) — no clinical-stage drug of this modality recorded.

Other modalitiesStrong

Approved Drug support this modality.

View underlying tractability evidence (9)
SM · Structure with LigandAB · Approved DrugAB · UniProt loc high confAB · GO CC high confAB · UniProt SigP or TMHMMAB · Human Protein Atlas locPR · Database UbiquitinationPR · Half-life DataOC · Approved Drug

Raw Open Targets tractability assessment buckets, by modality.

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein. Ranked by active status, then clinical phase and recency, and spread across the targeting drugs.

View all trials (26)

ENROLLING_BY_INVITATION · via ocrelizumab · NCT06495593

ClinicalTrials.gov via the drug-target graph.

What's happening now

12

Recent therapeutic activity around this target — regulatory actions, clinical trials and safety signals for 5 drugs that target this protein, plus publications where such a drug is a genuine subject. Every item is reached indirectly through the drug, not the protein itself; incidental mentions (a paper that merely measures a drug) and press items are excluded.

  1. Trial status changed2026-08-28

    Impact of Annual Versus Biannual Infusions of Ocrelizumab in Patients With Active MS,After 2 Years of Initial Treatment, on Freedom From Radiological Disease Activity at Two Years: a Multicenter Randomized Controlled Non-inferiority Trial

    Status changed to Active, not recruiting · ClinicalTrials.gov · via ocrelizumab

  2. Trial status changed2026-08-19

    A Phase 3 Randomized, Open-Label Multicenter Study of Zanubrutinib (BGB-3111) Plus Anti-CD20 Antibodies Versus Lenalidomide Plus Rituximab in Patients With Relapsed/Refractory Follicular or Marginal Zone Lymphoma

    Status changed to Active, not recruiting · ClinicalTrials.gov · via obinutuzumab

  3. Trial results posted2026-08-18

    Phase II, Single Arm, Open Label Multi-center Study of Obinutuzumab and Ibrutinib in the Front Line Treatment of Indolent Non-Hodgkin's Lymphomas

    Results posted · ClinicalTrials.gov · via obinutuzumab

  4. Trial results posted2026-07-24

    A Phase IIIB Multicenter, Randomized, Double-blind, Controlled Study to Evaluate the Efficacy, Safety and Pharmacokinetics of a Higher Dose of Ocrelizumab in Adults With Primary Progressive Multiple Sclerosis

    Results posted · ClinicalTrials.gov · via ocrelizumab

  5. Label change2026-06-22

    Label change: GLOFITAMAB (BLA761309)

    fda · regulatory · fda · via glofitamab

  6. Label change2026-06-17

    Label change: EPCORITAMAB-BYSP (BLA761324)

    fda · regulatory · fda · via epcoritamab

  7. Label change2026-05-28

    Label change: GLOFITAMAB (BLA761309)

    fda · regulatory · fda · via glofitamab

  8. Indication expanded2026-03-27

    Indication expansion: EPCORITAMAB-BYSP (BLA761324)

    fda · regulatory · fda · via epcoritamab

  9. New publication2016-12-21
    Ocrelizumab versus Interferon Beta-1a in Relapsing Multiple Sclerosis.

    The New England journal of medicine · 2017 · 1,424 citations · Europe PMC · via ocrelizumab

  10. New publication2016-12-21
    Ocrelizumab versus Placebo in Primary Progressive Multiple Sclerosis.

    The New England journal of medicine · 2017 · 1,348 citations · Europe PMC · via ocrelizumab

  11. Safety communication2014-12-11

    Drug Safety Update: Ofatumumab: screen for hepatitis B virus before treatment

    mhra · safety · mhra · via ofatumumab

  12. Safety communication2014-12-11

    Drug Safety Update: Ofatumumab▼: reminder of risk of serious and fatal infusion reactions

    mhra · safety · mhra · via ofatumumab

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.