How Does Kesimpta Target B Cells?
Kesimpta (ofatumumab) is a monoclonal antibody that binds to CD20 on the surface of B cells, marking them for destruction by the immune system. This depletes pre-B and mature B cells from circulation.[1][2]
What Happens to B Cells After Kesimpta Treatment?
B-cell counts drop rapidly after the first dose, often reaching near-zero levels within a week. Repopulation begins around 4-6 months post-treatment but remains altered for up to a year, with slower recovery of memory B cells.[1][3]
Why Is B-Cell Depletion Key for Kesimpta in MS?
Kesimpta treats relapsing multiple sclerosis (MS) by reducing B-cell mediated inflammation in the central nervous system. Clinical trials (ASCLEPIOS I/II) showed this depletion linked to 50-60% lower annualized relapse rates versus teriflunomide.[2][4]
How Long Until B Cells Recover Fully?
Full B-cell recovery typically takes 6-12 months after the last dose, though naive B cells repopulate faster than memory ones. Monitoring via blood tests guides retreatment decisions.[1][3]
Does Kesimpta Affect Other Immune Cells?
It primarily targets CD20-positive B cells, sparing plasma cells (which lack CD20) and T cells. This contrasts with broader immunosuppressants like rituximab, which has a similar mechanism but different dosing.[2][5]
What Risks Come with B-Cell Depletion?
Depletion raises infection risk (e.g., upper respiratory infections in 40% of patients) and potential hypogammaglobulinemia. Rare cases include progressive multifocal leukoencephalopathy (PML).[4][6]
[1]: Kesimpta Prescribing Information (Novartis)
[2]: FDA Approval Summary for Kesimpta
[3]: Sorensen PS et al. Lancet Neurol. 2021;20(2):114-124.
[4]: Hauser SL et al. N Engl J Med. 2020;383(6):533-543.
[5]: Kappos L et al. Lancet. 2020;395(10227):1021-1031.
[6]: EMA Kesimpta Summary of Product Characteristics.