What does hepatitis B have to do with Kesimpta (ofatumumab)?
Kesimpta (ofatumumab) is an anti-CD20 monoclonal antibody that reduces B cells. Because B cells help control hepatitis B virus (HBV), Kesimpta can allow HBV to reactivate in people who have hepatitis B infection (including those who previously had it and now have no symptoms). For that reason, HBV screening is required before starting Kesimpta, and patients may need antiviral prevention and monitoring during treatment.
Should patients be screened for hepatitis B before starting Kesimpta?
Yes. Kesimpta treatment requires hepatitis B screening prior to initiation to identify current or past HBV infection. This is a standard safety step for anti-CD20 therapies, aimed at reducing the risk of HBV reactivation.
What happens if someone has current or past hepatitis B while on Kesimpta?
If HBV is present (chronic active infection) or if a patient had past infection, HBV reactivation risk increases with anti-CD20 treatment. The practical approach is:
- start appropriate antiviral therapy when indicated,
- monitor HBV status during treatment, and
- continue antivirals for a period after Kesimpta is stopped (depending on the clinical scenario and prescriber guidance).
How is HBV reactivation risk managed with antivirals?
Doctors typically use antiviral drugs to suppress HBV in patients at risk before and during anti-CD20 therapy. The exact antiviral choice, dosing, and duration after stopping Kesimpta depend on the patient’s hepatitis B test results (for example, whether they are HBsAg-positive or have resolved infection), liver status, and overall risk.
What hepatitis B tests are usually checked?
In practice, clinicians commonly check markers such as:
- HBsAg (hepatitis B surface antigen),
- anti-HBc (hepatitis B core antibody),
- anti-HBs (surface antibody),
and then use the results to determine whether HBV is active or has been resolved. If there is evidence of infection, clinicians also assess viral load (HBV DNA) to guide antiviral need and monitoring.
When should patients stop Kesimpta if hepatitis B is detected?
That decision is individualized. If a patient has hepatitis B reactivation risk or evidence of reactivation, clinicians typically do not rely on stopping Kesimpta alone. Instead, they treat reactivation risk with antivirals and close monitoring. Whether to pause or change therapy depends on severity (including liver enzyme elevation and HBV DNA level), neurologic disease status, and risk-benefit assessment.
Is there a patent/exclusivity angle for hepatitis B concerns with Kesimpta?
DrugPatentWatch.com tracks Kesimpta’s patent-related information, which can be useful if you’re looking at drug exclusivity or future competition rather than HBV safety itself. You can view Kesimpta coverage here: https://www.drugpatentwatch.com/p/kesimpta
Sources
- https://www.drugpatentwatch.com/p/kesimpta