Ofatumumab is an anti-CD20 antibody used for the treatment of chronic lymphocytic leukemia (CLL) in selected patients with certain treatment histories and responsiveness to anticancer medications.

Brand Names
Arzerra, Kesimpta
Generic Name
DrugBank Accession Number

Ofatumumab is a novel anti-CD20 monoclonal antibody that targets B-cells. It is an IgG1κ human monoclonal antibody produced from a recombinant murine cell line (NS0) via transgenic mouse and hybridoma technology.6 Ofatumumab works by recognizing antigens that are expressed on the tumour cells in certain cancers; however, the antigen is not tumour-specific and can also be found in normal B-cells.1 Ofatumumab was first approved by the FDA in 2009.8 It is used in the treatment of recurrent, progressive, or recurrent chronic lymphocytic leukemia (CLL) or CLL in treatment-naive patients in whom fludarabine-based therapy is considered inappropriate. Ofatumumab is used as monotherapy or in combination with other medications, depending on the patient profile and previous treatment history.6 Although it has a similar molecular mechanism of action as rituximab, another CD-20 monoclonal antibody used in the treatment of rheumatoid arthritis and B-cell non-Hodgkin's lymphoma, ofatumumab has a higher affinity towards CD20.1

Ofatumumab is available for intravenous administration and is marketed as Arzerra. In Phase III clinical trials consisting of subjects with relapsing forms of multiple sclerosis (RMS), subcutaneous administration of ofatumumab reduced the number of relapses and delayed disease progression. In February 2020, FDA and EMA approved Supplemental Biologics License Application (sBLA) and Marketing Authorization Application (MAA), respectively, for ofatumumab for the treatment of RMS in adults.7 The FDA subsequently approved ofatumumab for the treatment of RMS on August 20, 2020.9 The potential therapeutic use of ofatumumab in various lymphomas and rheumatoid arthritis has also been investigated.4

Biologic Classification
Protein Based Therapies
Monoclonal antibody (mAb)
Protein Structure
Protein Chemical Formula
Protein Average Weight
146100.0 Da
>Ofatumumab Heavy Chain
>Ofatumumab Light Chain
Download FASTA Format
  • HuMax-CD20
  • HuMax-CD20, 2F2
  • Ofatumumab
  • Ofatumumabum
External IDs
  • GSK 1841157
  • GSK-1841157
  • GSK1841157
  • GSKI841157
  • HSDB 8170
  • OMB 157
  • OMB-157
  • OMB157



Ofatumumab is indicated, in combination with chlorambucil, for the treatment of previously untreated patients with chronic lymphocytic leukemia (CLL) for whom fludarabine-based therapy is considered inappropriate.6

In patients with recurrent or progressive CLL, ofatumumab is indicated for extended treatment of patients who are in complete or partial response after at least two lines of therapy for recurrent or progressive CLL.6

Ofatumumab is indicated for the treatment of patients with CLL refractory to fludarabine and alemtuzumab.6

Ofatumumab is also indicated for the treatment of adult patients with relapsing forms of multiple sclerosis, including active secondary progressive disease, clinically isolated syndrome, and relapsing-remitting disease.9

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Associated Conditions
Indication TypeIndicationCombined Product DetailsApproval LevelAge GroupPatient CharacteristicsDose Form
Used in combination to treatChronic lymphocytic leukemiaRegimen in combination with: Chlorambucil (DB00291)••••••••••••••••••••• •••••• •••••••••• ••• ••••••••••••••••• ••••••••••••••••
Treatment ofClinically isolated syndrome (cis)••••••••••••••••••••••••••
Treatment ofRefractory chronic lymphocytic leukemia•••••••••••••••••••••• •• ••••••••••• ••• ••••••••••••••••••••
Treatment ofRelapsing multiple sclerosis (rms)••••••••••••••••••••••••••
Treatment ofRelapsing remitting multiple sclerosis (rrms)••••••••••••••••••••••••••
Contraindications & Blackbox Warnings
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Ofatumumab works by binding to and blocking the action of CD-20, a molecule expressed on the surface of both healthy and leukemic B lymphocytes. In patients with previously untreated chronic lymphocytic leukemia (CLL), ofatumumab caused B-cell depletion in the peripheral blood after six months following the last dose. However, observable depletion of B cells in the peripheral blood does not directly correlate with the depletion of B-cells in solid organs or malignant tumours.6 In vitro, ofatumumab induces complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC).1

Mechanism of action

CD20 is expressed on normal pre-B lymphocytes and mature B lymphocytes, as well as malignant B lymphocytes. Numerous studies demonstrate that the depletion of B-cells can significantly alleviate symptoms of many forms of leukemia and lymphoma, which are malignancies associated with B-cell dysfunctions and high expression of CD20.4

Ofatumumab is an anti-CD20 monoclonal antibody that binds to the small and large extracellular loops of the CD20 molecule. The Fab domain of ofatumumab binds to CD20, and this drug-target interaction does not result in immediate shedding and internalization of CD20 from the plasma membrane of B lymphocytes.2,6 This allows ofatumumab to persist on the B lymphocyte cell surface for an extended period and recruit immunological molecules or FcR-expressing innate effectors, such as macrophages, that mediate immune effector functions with strong cytotoxic effects.2,4 These immune effector functions include complement-dependent cytotoxicity (CCD) and antibody-dependent cellular cytotoxicity (ADCC), which promote the lysis of malignant B-cells.2,4,6 Complement-dependent cytotoxicity (CDC) involves translocation of the CD20 molecule into lipid rafts, which are involved in cell signalling and receptor trafficking.1

The mechanism by which ofatumumab exerts a therapeutic effect in multiple sclerosis patients is unknown but is presumed to still occur as a consequence of its ability to bind CD20.9

AB-lymphocyte antigen CD20

In one study consisting of patients with relapsed or refractory chronic lymphocytic leukemia and small lymphocytic lymphoma, the Cmax was 94 μg/mL and the Tmax was 7.3 hours following the first infusion of 300 mg ofatumumab.5

Following subcutaneous injection, ofatumumab is thought to be absorbed primarily into the lymphatic system. Subcutaneous dosing of 20 mg every four weeks resulted in a mean AUCtau of 483 μg*h/mL and a mean steady-state Cmax of 1.43 μg/mL.9

Volume of distribution

In patients with CLL, the mean volume of distribution at steady-state was 5.8 L.6

Repeated subcutaneous dosing with 20 mg of ofatumumab resulted in a steady-state volume of distribution of 5.42 L.9

Protein binding

There is limited information on the serum protein binding profile of ofatumumab.


Like other monoclonal antibodies, ofatumumab is expected to undergo lysosomal degradation by the reticuloendothelial system and protein catabolism by a target‐mediated disposition pathway.3

Route of elimination

Ofatumumab undergoes elimination by a target-independent route and a target (B cell)-mediated route, with a dose-dependent clearance in the dose range of 100 to 2000 mg. As ofatumumab causes B-cell depletion, the clearance of ofatumumab mediated by B-cells is decreased substantially after subsequent drug infusions.6


In patients with CLL, the mean half-life at steady state was 17.1 days.6 Similarly, in patients given ofatumumab subcutaneously, the steady-state elimination half-life was estimated at 16 days.9


In patients with CLL, the mean clearance at steady-state was 11.6 mL/hour.6

In patients administered ofatumumab subcutaneously in repeated 20 mg injections, the steady-state clearance following B-cell depletion was estimated to be 0.34 L/day.9

Adverse Effects
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There is limited information on overdose of ofatumumab. Ofatumumab may cause B-cell depletion in the fetus when administered in pregnant women.6

Not Available
Pharmacogenomic Effects/ADRs
Not Available


Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
AbataceptThe risk or severity of adverse effects can be increased when Abatacept is combined with Ofatumumab.
AbciximabThe risk or severity of adverse effects can be increased when Abciximab is combined with Ofatumumab.
AdalimumabThe risk or severity of adverse effects can be increased when Adalimumab is combined with Ofatumumab.
Adenovirus type 7 vaccine liveThe risk or severity of infection can be increased when Adenovirus type 7 vaccine live is combined with Ofatumumab.
AducanumabThe risk or severity of adverse effects can be increased when Ofatumumab is combined with Aducanumab.
Food Interactions
No interactions found.


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International/Other Brands
Kesimpta (Novartis)
Brand Name Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing EndRegionImage
ArzerraInjection, solution20 mg/1mLIntravenousNovartis Pharmaceuticals Corporation2016-02-01Not applicableUS flag
ArzerraInjection, solution, concentrate100 mgIntravenousNovartis Europharm Limited2021-01-122019-02-25EU flag
ArzerraSolution1000 mg / 50 mLIntravenousNovartis2012-08-132019-03-01Canada flag
ArzerraInjection, solution20 mg/1mLIntravenousNovartis Pharmaceuticals Corporation2016-02-01Not applicableUS flag
ArzerraInjection, solution20 mg/1mLIntravenousGlaxosmithkline Inc2011-07-222017-08-31US flag


ATC Codes
L01FA02 — OfatumumabL04AG12 — Ofatumumab
Drug Categories
Chemical TaxonomyProvided by Classyfire
Not Available
Organic Compounds
Super Class
Organic Acids
Carboxylic Acids and Derivatives
Sub Class
Amino Acids, Peptides, and Analogues
Direct Parent
Alternative Parents
Not Available
Not Available
Molecular Framework
Not Available
External Descriptors
Not Available
Affected organisms
  • Humans and other mammals

Chemical Identifiers

CAS number


General References
  1. Lin TS: Ofatumumab: a novel monoclonal anti-CD20 antibody. Pharmgenomics Pers Med. 2010;3:51-9. Epub 2010 May 10. [Article]
  2. Glennie MJ, French RR, Cragg MS, Taylor RP: Mechanisms of killing by anti-CD20 monoclonal antibodies. Mol Immunol. 2007 Sep;44(16):3823-37. [Article]
  3. Ryman JT, Meibohm B: Pharmacokinetics of Monoclonal Antibodies. CPT Pharmacometrics Syst Pharmacol. 2017 Sep;6(9):576-588. doi: 10.1002/psp4.12224. Epub 2017 Jul 29. [Article]
  4. Zhang B: Ofatumumab. MAbs. 2009 Jul-Aug;1(4):326-31. doi: 10.4161/mabs.1.4.8895. Epub 2009 Jul 1. [Article]
  5. Ogura M, Hatake K, Tobinai K, Uchida T, Suzuki T, Terui Y, Yokoyama M, Maruyama D, Mori M, Jewell RC, Katsura K, Hotta T: Phase I study of ofatumumab, a human anti-CD20 antibody, in Japanese patients with relapsed or refractory chronic lymphocytic leukemia and small lymphocytic lymphoma. Jpn J Clin Oncol. 2013 May;43(5):466-75. doi: 10.1093/jjco/hyt022. Epub 2013 Feb 28. [Article]
  6. FDA Approved Drug Products: ARZERRA (ofatumumab) injection, for intravenous use [Link]
  7. Novartis announces FDA and EMA filing acceptance of ofatumumab, a novel B-cell therapy for patients with relapsing forms of multiple sclerosis (RMS) [Link]
  8. Arzerra (ofatumumab) FDA Approval History - Drugs.com [Link]
  9. FDA Approved Drug Products: KESIMPTA (ofatumumab) injection [Link]
  10. FDA Approved Drug Products: KESIMPTA® (ofatumumab) injection, for subcutaneous use (Jan 2024) [Link]
PubChem Substance
RxList Drug Page
Drugs.com Drug Page
FDA label
Download (153 KB)
Download (92 KB)

Clinical Trials

Clinical Trials
Clinical Trial & Rare Diseases Add-on Data Package
Explore 4,000+ rare diseases, orphan drugs & condition pairs, clinical trial why stopped data, & more. Preview package
PhaseStatusPurposeConditionsCountStart DateWhy Stopped100+ additional columns
4Active Not RecruitingTreatmentRelapsing Multiple Sclerosis (RMS)1somestatusstop reasonjust information to hide
4Active Not RecruitingTreatmentRelapsing Remitting Multiple Sclerosis (RRMS)2somestatusstop reasonjust information to hide
4CompletedTreatmentChronic Lymphocytic Leukemia1somestatusstop reasonjust information to hide
4CompletedTreatmentCoronavirus Disease 2019 (COVID‑19) / Multiple Sclerosis1somestatusstop reasonjust information to hide
4CompletedTreatmentCoronavirus Disease 2019 (COVID‑19) / Relapsing Multiple Sclerosis (RMS)1somestatusstop reasonjust information to hide


Not Available
Not Available
Dosage Forms
InjectionIntravenous20 mg/1mL
Injection, solutionIntravenous20 mg/1mL
Injection, solution, concentrateIntravenous
Injection, solution, concentrateIntravenous100 mg
Injection, solution, concentrateIntravenous1000 mg
SolutionIntravenous100 mg / 5 mL
SolutionIntravenous1000 mg / 50 mL
Injection, solutionIntravenous100 mg
Injection, solutionIntravenous1000 mg
SolutionSubcutaneous20.000 mg
Solution20 mg/0.4mL
Injection, solution20 mg/0.4ml
Injection, solutionSubcutaneous20 mg/0.4mL
Injection, solutionSubcutaneous20 MG
SolutionSubcutaneous20 mg / 0.4 mL
SolutionSubcutaneous50 mg
Not Available
Patent NumberPediatric ExtensionApprovedExpires (estimated)Region
US8337847No2012-12-252028-11-25US flag
US8975282No2015-03-102032-07-28US flag


Experimental Properties
Not Available


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Pharmacological action
General Function
Mhc class ii protein complex binding
Specific Function
This protein may be involved in the regulation of B-cell activation and proliferation.
Gene Name
Uniprot ID
Uniprot Name
B-lymphocyte antigen CD20
Molecular Weight
33076.99 Da
  1. Dorner T, Burmester GR: New approaches of B-cell-directed therapy: beyond rituximab. Curr Opin Rheumatol. 2008 May;20(3):263-8. doi: 10.1097/BOR.0b013e3282f5e08d. [Article]
  2. Glennie MJ, French RR, Cragg MS, Taylor RP: Mechanisms of killing by anti-CD20 monoclonal antibodies. Mol Immunol. 2007 Sep;44(16):3823-37. [Article]
  3. Du J, Yang H, Guo Y, Ding J: Structure of the Fab fragment of therapeutic antibody Ofatumumab provides insights into the recognition mechanism with CD20. Mol Immunol. 2009 Jul;46(11-12):2419-23. doi: 10.1016/j.molimm.2009.04.009. Epub 2009 May 8. [Article]
  4. Schnaiter A, Stilgenbauer S: Refractory chronic lymphocytic leukemia--new therapeutic strategies. Oncotarget. 2010 Nov;1(7):472-82. doi: 10.18632/oncotarget.101103. [Article]
  5. Kyriakidis I, Vasileiou E, Rossig C, Roilides E, Groll AH, Tragiannidis A: Invasive Fungal Diseases in Children with Hematological Malignancies Treated with Therapies That Target Cell Surface Antigens: Monoclonal Antibodies, Immune Checkpoint Inhibitors and CAR T-Cell Therapies. J Fungi (Basel). 2021 Mar 5;7(3). pii: jof7030186. doi: 10.3390/jof7030186. [Article]

Drug created at March 19, 2008 16:44 / Updated at April 23, 2024 11:38