Type II anti-CD20 monoclonal antibody Pregnancy: Can cause fetal B-cell depletion based on animal studies and mechanism of action; monoclonal antibodies are transferred across the placenta. There are no data in pregnant women to inform a drug-associated risk. Advise pregnant women of the potential risk to the fetus.

Obinutuzumab (Specialist drug)

Brand names: Gazyvaro

Obinutuzumab is a glycoengineered type II anti-CD20 monoclonal antibody given by intravenous infusion, licensed in haematology for chronic lymphocytic leukaemia and follicular lymphoma in combination with chemotherapy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Chronic lymphocytic leukaemia: 100 mg on day 1 and 900 mg on day 2 of Cycle 1, then 1,000 mg on days 8 and 15 of Cycle 1, then 1,000 mg on day 1 of Cycles 2-6

Route: Intravenous infusion through a dedicated line. Must NOT be given as an intravenous push or bolus

Frequency: Six 28-day treatment cycles as scheduled above

Premedicate before each infusion for infusion-related reactions, and give prophylactic hydration and anti-hyperuricaemics to patients at high risk of tumour lysis syndrome. Should only be administered by a healthcare professional with medical support able to manage severe, potentially fatal infusion-related reactions. Monitor blood counts at regular intervals. OTHER INDICATIONS (US labelling): follicular lymphoma - 1,000 mg on days 1, 8 and 15 of Cycle 1, 1,000 mg on day 1 of Cycles 2-6 or 2-8, then 1,000 mg every 2 months for up to 2 years (given with bendamustine over six 28-day cycles, with CHOP over six 21-day cycles followed by 2 further 21-day cycles alone, or with CVP over eight 21-day cycles); active lupus nephritis - 1,000 mg at the initial infusion, then at Week 2, Week 24, Week 26 and every 6 months thereafter. INFUSION RATES (CLL): day 1 at 25 mg/hr over 4 hours - do not increase; day 2 at 50 mg/hr (25 mg/hr if a previous infusion-related reaction), escalating by up to 50 mg/hr every 30 minutes to a maximum of 400 mg/hr; days 8 and 15 may start at 100 mg/hr and increase by 100 mg/hr every 30 minutes to a maximum of 400 mg/hr if no prior reaction. If a planned dose is missed, give it as soon as possible and adjust the schedule to maintain the interval between doses. SOURCE CAVEAT: no UK SPC posology was retrieved for this drug - the dose above is taken from the US prescribing information for Gazyva (label date 2025-12-19) and must be verified against the current UK SPC before use.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known hypersensitivity reactions (e.g. anaphylaxis) to obinutuzumab or to any of the excipients
Serum sickness with prior obinutuzumab use

Side effects

Infusion-related reactions
Neutropenia and thrombocytopenia
Infections including upper respiratory tract infection, urinary tract infection, bronchitis and pneumonia
Fatigue, cough, musculoskeletal pain
Constipation and diarrhoea
Tumour lysis syndrome; hepatitis B reactivation; progressive multifocal leukoencephalopathy; disseminated intravascular coagulation

Clinical monograph

How it works

It binds the CD20 antigen on B cells and causes potent B-cell depletion mainly via direct cell death and antibody-dependent cellular cytotoxicity/phagocytosis, with relatively less complement-dependent cytotoxicity than rituximab.

Prescribing in practice

Screen for hepatitis B before treatment, as B-cell depletion can cause hepatitis B reactivation that may be fatal — do not start without checking serology and arranging appropriate prophylaxis and monitoring.
Tumour lysis syndrome and severe infusion-related reactions can occur, especially with the first infusion and high tumour burden, so use premedication, hydration and close monitoring.
Neutropenia and infection are common, and rare progressive multifocal leukoencephalopathy has been reported, warranting prompt assessment of new neurological symptoms.

Monitoring

Monitor full blood count, signs of infection, infusion reactions and biochemical markers of tumour lysis, and stay alert to hepatitis B reactivation and neurological changes during and after therapy.

Counselling the patient

Report any fever or signs of infection straight away.
Tell us about new neurological symptoms such as confusion or vision change.
Avoid live vaccines during and for some time after treatment.

Evidence & guidelines

Its haematological indications are established through pivotal randomised trials demonstrating improved progression-free survival when combined with chemotherapy.

Reference: NICE TA343/TA513; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways