[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/) › Obinutuzumab

# Obinutuzumab

## Antineoplastic monoclonal antibodies?

Antineoplastic monoclonal antibodies

## High alert?

An error with this medicine can cause serious harm: double checks and protocols are used.

Glycoengineered anti-CD20 antibody with stronger immune killing than rituximab. For CLL and follicular lymphoma; can reactivate hepatitis B.

Updated Nov 1, 2026

## Quick facts

**Group**
[Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/)

**Target**
CD20 (B-lymphocyte surface antigen)

**Used for**
Follicular lymphoma · Also used for lupus nephritis

**Key effects**
Infusion reactions · Muscle or joint pain · Tiredness

**Monitor**
Hepatitis B blood test before starting · Blood count

**ATC**
L01FA03

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

◆**CD20 (B-lymphocyte surface antigen)**Obinutuzumab

ⓘ The cryo-electron microscopy structure shows full-length human CD20 in the membrane with obinutuzumab Fab arms bound.

**Target in 3D:** CD20 (B-lymphocyte surface antigen). PDB structure 6Y97 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6Y97) · Drag to rotate · pinch to zoom

Obinutuzumab is a humanised IgG1 antibody against CD20, a protein on the surface of normal and malignant B cells. Once bound, it kills the B cell through complement (CDC) and through immune effector cells (ADCC). The sugar chains on its Fc portion were changed (glycoengineering) so that it binds effector immune cells more strongly; it was the first glycoengineered antibody approved.

- Obinutuzumab binds CD20 on B cells
- Its modified Fc recruits immune killer cells strongly
- B cells, malignant and normal, are destroyed

## Indications

- Previously untreated chronic lymphocytic leukaemia, with chlorambucil. [Chronic lymphocytic leukaemia →](https://durgical.com/en/conditions/chronic-lymphocytic-leukaemia/)
- Follicular lymphoma: with bendamustine after rituximab failure, or with chemotherapy as first line, then alone as maintenance. [Non-Hodgkin lymphoma →](https://durgical.com/en/conditions/non-hodgkin-lymphoma/)
- Also used for lupus nephritis, by blocking immune cells that damage the kidney.

## Adverse effects

### Common

- Infusion reactions, mostly with the first infusion
- Muscle or joint pain, headache, itching
- Constipation, diarrhoea, decreased appetite
- Tiredness, trouble sleeping

### Serious (rare, important)

- Hepatitis B reactivation, which can be fatal
- Progressive multifocal leukoencephalopathy (PML)
- Severe infusion reactions
- Serious infections, low blood counts and bleeding
- Deep vein thrombosis

## Contraindications

- None stated in the sources used; hepatitis B is tested and treated first

## Key interactions

**Vaccines**
No vaccinations are given during treatment without asking the treating doctor.

**Chlorambucil or bendamustine (combination regimens)**
Intended combinations; they add to low blood counts and infection risk.

## What is monitored

- Hepatitis B blood test before starting, and signs of hepatitis during and for months after treatment
- Vital signs during each infusion
- Blood count
- New confusion, imbalance, speech or vision changes (PML)

## Administration and safety

- Slow intravenous infusion by a doctor or nurse; medicines are given before each infusion to prevent reactions.
- The patient is watched closely during the infusion; it is slowed or stopped for a reaction.

## Pregnancy and breastfeeding

Effective contraception is used during treatment and for months after the last dose, and breastfeeding is avoided for the same period.

## Nursing care

- Confirm the hepatitis B test result before the first dose.
- Ask about heart, lung, kidney or liver disease and any current or recurring infection.
- Teach to report fever, cough, yellow skin, leg pain or swelling, bleeding, and any sudden change in thinking, balance, speech or vision.
- No vaccinations without asking the treating doctor.

## Pharmacokinetics

**Absorption**
Slow intravenous infusion.

**Elimination**
Broken down like other IgG antibodies, by protein catabolism.

## Memory aid

OBINutuzumab = rituximab's 'sugar-tuned' cousin: a reshaped Fc brings more killer cells. Before the first dose, check hepatitis B.

## Test yourself

Think of the answer, then tap the question to see it.

## What is special about the Fc portion of obinutuzumab?

Its sugars were glycoengineered to bind immune effector cells more strongly, boosting ADCC.

## Which two boxed-warning risks does obinutuzumab carry?

Hepatitis B reactivation and progressive multifocal leukoencephalopathy.

## With which drug is obinutuzumab combined in untreated CLL?

Chlorambucil.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/obinutuzumab/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 3

- [Rituximab](https://durgical.com/en/pharmacology/rituximab/)
- [Chlorambucil](https://durgical.com/en/pharmacology/chlorambucil/)
- [Bendamustine](https://durgical.com/en/pharmacology/bendamustine/)

## Related conditions 2

- [Chronic lymphocytic leukaemia](https://durgical.com/en/conditions/chronic-lymphocytic-leukaemia/)
- [Non-Hodgkin lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/)

[← Back to the class: Antineoplastic monoclonal antibodies](https://durgical.com/en/pharmacology/classes/antineoplastic-monoclonal-antibodies/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Obinutuzumab Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a614012.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [Obinutuzumab - NCI](https://www.cancer.gov/about-cancer/treatment/drugs/obinutuzumab) (National Cancer Institute (U.S.), 2026); [Structure of full-length CD20 in complex with Obinutuzumab Fab](https://www.rcsb.org/structure/6Y97) (RCSB Protein Data Bank, 2020).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/obinutuzumab/