# CD79b

Source: https://onco.cc/targets/cd79b/  
OnCo record `cd79b` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Part of the B-cell receptor found on nearly all B-cell lymphomas; the target of the ADC polatuzumab vedotin and a frequently mutated gene in brain and testicular lymphoma.

## Summary

CD79b (Igβ) pairs with CD79a to form the signalling subunit of the B-cell receptor. It is expressed on >95% of B-cell lymphomas and rapidly internalises, making it an ideal ADC target: polatuzumab vedotin (approved 2019; POLARIX first line 2023) is the only approved agent. CD79B Y196 mutations drive chronic active BCR signalling in ABC-DLBCL (MCD/C5 cluster), PCNSL and testicular lymphoma, and predict BTK-inhibitor sensitivity. CD79b CAR-T and bispecifics are in trials.

## Fields

- Kind: Target
- Last checked: 2026-09-08
- Tags: gap-fill
- Symbol: CD79B
- Class: surface-antigen
- Biology: Transmembrane Ig-superfamily protein with an ITAM motif; together with CD79a it couples antigen binding to SYK/BTK/PI3K signalling and mediates BCR internalisation.
- Where found: DLBCL (>95% expression; ~20% CD79B mutation in ABC subtype); Follicular and mantle cell lymphoma (expression); Primary CNS lymphoma (CD79B mutation ~60%); CLL (lower expression)

## Notes

- Lymphoma: More than 95% of diffuse large B-cell lymphomas express it, and so do follicular and mantle cell lymphoma. It is half of the signalling heterodimer of the B-cell receptor, with CD79a. Also on healthy cells: Normal B cells, and strongly: the Human Protein Atlas reads CD79B at 1,489 nTPM in the B-cell lineage, the highest of any lymphoma surface target. What the medicine does: CD79b is part of the receptor complex that is continuously internalised, which makes it an unusually good address for a conjugate: polatuzumab vedotin delivers monomethyl auristatin E inside the cell. Nothing is tested before it is given, because expression is close to universal. How tumours lose it: No established escape route is published for CD79b in the way it is for CD19 and CD20. That is a gap in the literature rather than evidence that the antigen is never lost. What that costs the patient: Peripheral neuropathy and neutropenia from the auristatin payload rather than from the antigen, plus the same B-cell depletion as the rest of this group when it is given with rituximab.
- Lymphoma, Chronic active B-cell receptor signalling, and BTK: The B-cell receptor normally signals only when it meets antigen. In activated B-cell-like lymphoma it signals continuously: the receptors cluster in the membrane and diffuse slowly, exactly as they do in an antigen-stimulated normal B cell, and knocking down IgM, Ig-kappa, CD79A, CD79B or BTK kills the cell. The signal runs CD79a/b to SYK to BTK to PLC-gamma-2 to protein kinase C beta to the CARD11-BCL10-MALT1 complex and into NF-kB. Mutations of the ITAM module of CD79B raise surface receptor expression and blunt LYN, the feedback brake (Davis 2010). Frequency: Mutations of the first ITAM tyrosine of CD79B in 18% of activated B-cell-like cases, frequent in that subtype and rare in other diffuse large B-cell lymphomas, absent from Burkitt and MALT lymphoma; activating CARD11 mutations in roughly 10% of activated B-cell-like cases (Davis 2010). What it changes about treatment: This is the one pathway in lymphoma where the biology picks the drug today. BTK inhibitors are standard in mantle cell lymphoma and Waldenstrom macroglobulinaemia and have activity in primary CNS lymphoma and in the MCD genetic subtype of diffuse large B-cell lymphoma; they do little in germinal-centre disease.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/CD79B
- Polatuzumab (Blood 2015): https://doi.org/10.1182/blood-2015-06-651380
- Davis et al., Nature 2010: chronic active B-cell receptor signalling in diffuse large B-cell lymphoma: https://doi.org/10.1038/nature08638

## Connected records

- cancers: [Diffuse large B-cell lymphoma](https://onco.cc/cancers/dlbcl/), [Follicular lymphoma](https://onco.cc/cancers/follicular-lymphoma/), [Mantle cell lymphoma](https://onco.cc/cancers/mantle-cell-lymphoma/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/), [Primary CNS lymphoma](https://onco.cc/cancers/primary-cns-lymphoma/), [Primary mediastinal (thymic) large B-cell lymphoma](https://onco.cc/cancers/primary-mediastinal-b-cell-lymphoma/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/)
- drugs: [Polatuzumab vedotin](https://onco.cc/drugs/polatuzumab-vedotin/)
- pathways: [B-cell receptor / BTK signalling (to NF-κB)](https://onco.cc/pathways/bcr-signalling/), [Inflammation & NF-κB](https://onco.cc/pathways/inflammation-nfkb/)
- terms: [Antigen escape: how a lymphoma loses the thing the drug was aimed at](https://onco.cc/terms/lymphoma-bio-antigen-escape/), [Cell of origin (GCB vs ABC)](https://onco.cc/terms/cell-of-origin/), [Cell of origin in practice: Hans against expression profiling, and what it changes](https://onco.cc/terms/lymphoma-bio-cell-of-origin-in-practice/), [LymphGen and the genetic clusters of large B-cell lymphoma](https://onco.cc/terms/lymphoma-bio-lymphgen/), [MYD88 L265P and CXCR4 mutations](https://onco.cc/terms/myd88-l265p/), [What it costs to aim at a lineage antigen](https://onco.cc/terms/lymphoma-bio-lineage-antigen-cost/)
- key papers: [A probabilistic classification tool for genetic subtypes of diffuse large B cell lymphoma with therapeutic implications](https://onco.cc/key-papers/paper-wright-lymphgen-genetic-subtypes-dlbcl-cancer-cell-2020/), [Genetics and pathogenesis of diffuse large B-cell lymphoma](https://onco.cc/key-papers/paper-schmitz-genetics-pathogenesis-dlbcl-nejm-2018/), [Molecular subtypes of diffuse large B cell lymphoma are associated with distinct pathogenic mechanisms and outcomes](https://onco.cc/key-papers/paper-chapuy-molecular-subtypes-dlbcl-nat-med-2018/), [Phase 2 study of the bispecific T-cell engager (BiTE) antibody blinatumomab in relapsed/refractory diffuse large B-cell lymphoma](https://onco.cc/key-papers/paper-viardot-blood/), [POLARIX: swapping vincristine for the antibody-drug conjugate polatuzumab vedotin in first-line treatment of diffuse large B-cell lymphoma](https://onco.cc/key-papers/paper-polarix-polatuzumab-rchp-nejm-2022/), [Polatuzumab vedotin plus rituximab, gemcitabine, and oxaliplatin in relapsed or refractory diffuse large B-cell lymphoma: results from the phase III, randomized POLARGO trial](https://onco.cc/key-papers/paper-polargo-polatuzumab-r-gemox-dlbcl-jco-2026/)
- biomarkers: [CD79B ITAM mutation](https://onco.cc/biomarkers/cd79b-itam-mutation/)
- trials: [POLAR BEAR](https://onco.cc/trials/polar-bear/), [POLARGO](https://onco.cc/trials/polargo/)
- roadmaps: [Lymphoma roadmap: from a jaw tumour in Uganda and the first human cancer virus to gene-expression subtypes, PET-adapted chemotherapy, CAR-T cells, bispecific antibodies and the genetics-directed trials now recruiting](https://onco.cc/roadmaps/lymphoma-roadmap/)
- ideas: [Assign first-line treatment in diffuse large B-cell lymphoma by genetic subtype, not by a three-antibody stain](https://onco.cc/ideas/lymphoma-ev-genetic-subtype-directed-first-line/)

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