Kesimpta (ofatumumab) — the complete 2026 guide: how it works, efficacy, self-injection at home, and access in Serbia

July 1, 2026

Kesimpta (ofatumumab) is a high-efficacy anti-CD20 therapy for relapsing-remitting MS, given as a once-monthly subcutaneous injection self-administered at home — no infusion, no hospital day. A detailed guide: mechanism, ASCLEPIOS trial data, safety, pregnancy, how to use the Sensoready pen, and its status on Serbia's RFZO list.

What is Kesimpta

When I first started looking for MS information, what I needed most was a clear explanation without grand promises. Kesimpta is the brand name for ofatumumab, a fully human anti-CD20 monoclonal antibody that depletes B lymphocytes — the immune cells that drive inflammation and demyelination in multiple sclerosis. Developed by Novartis, approved by the FDA in August 2020 and by the EMA in March 2021 ([Novartis, 20 Aug 2020](https://www.novartis.com/news/media-releases/novartis-receives-fda-approval-kesimpta-ofatumumab-first-and-only-self-administered-targeted-b-cell-therapy-relapsing-multiple-sclerosis); [EMA EPAR — Kesimpta](https://www.ema.europa.eu/en/medicines/human/EPAR/kesimpta)). The key difference from Ocrevus: Kesimpta is a once-monthly subcutaneous injection that patients give themselves at home — no infusion, no hospital day.

How it works

Ofatumumab binds a different epitope on the CD20 receptor of B lymphocytes than ocrelizumab (Ocrevus) or rituximab — a small extracellular loop closer to the cell membrane. That triggers strong complement-dependent cytotoxicity (CDC) at very low doses, so 20 mg subcutaneously per month achieves B-cell depletion comparable to far larger intravenous doses of other anti-CD20 drugs ([Hauser SL et al. NEJM 2020 — ASCLEPIOS I/II](https://www.nejm.org/doi/full/10.1056/NEJMoa1917246)). Mature B cells in the blood are removed, while stem cells and plasma cells are spared.

Who it is approved for

- Relapsing-remitting MS (RRMS) in adults.

- Active secondary progressive MS (SPMS) — when relapses or new MRI lesions are still present.

- NOT approved for primary progressive MS (PPMS) — for that indication only Ocrevus remains approved.

What ASCLEPIOS I and II showed

Two identical phase 3 trials with 1,882 patients compared Kesimpta with teriflunomide (Aubagio) for up to 2.5 years ([Hauser SL et al. NEJM 2020](https://www.nejm.org/doi/full/10.1056/NEJMoa1917246)):

- 50.5% fewer relapses per year in ASCLEPIOS I and 58.5% fewer in ASCLEPIOS II than with teriflunomide.

- 94% fewer T1 Gd+ lesions and 82% fewer new or enlarging T2 lesions on MRI.

- 34.4% lower risk of confirmed disability progression at 3 months.

- NEDA-3 (no evidence of disease activity) in 47% of patients at year 2, vs 24% on teriflunomide.

Long-term data — the ALITHIOS extension

The open-label ALITHIOS extension has now followed over 1,700 patients for 5+ years ([Hauser SL et al., Mult Scler J 2023](https://journals.sagepub.com/doi/10.1177/13524585231202096); [Cross AH et al., AAN 2024](https://www.neurology.org/doi/10.1212/WNL.0000000000204614)). The key findings:

- Annualised relapse rate remains <0.05 in patients who started on Kesimpta from day one.

- Patients switched early from teriflunomide to Kesimpta had significantly less disability than those switched later — another confirmation of the "early and hard" principle.

- The safety profile has not worsened over 5+ years; no increase in malignancies was observed.

How it is given — the Sensoready pen at home

Kesimpta comes in a Sensoready autoinjector pen (or a prefilled syringe) of 20 mg / 0.4 ml. Dosing schedule:

- Three loading doses: day 0, week 1, and week 2.

- Then: one injection per month, starting from week 4.

How to administer it

1. Take the pen out of the fridge and let it sit for 15–30 minutes at room temperature (do not warm it).

2. Wash hands, disinfect the injection site (abdomen, thigh, or upper arm) and rotate sites each time.

3. Remove the cap, press the pen at 90° against the skin — the automatic injection lasts ~15 seconds; the yellow indicator moves until it shows "done".

4. Dispose of the needle in a sharps container.

What the first few doses typically feel like

The most common reaction is a "flu-like" feeling (mild fever, muscle aches, headache, fatigue) — it occurs in ~20% of patients after the first dose, lasts 24–48 hours, and becomes less frequent with later doses. Injection-site reactions (redness, mild stinging) are also common and mild.

Safety — what to know

Most common adverse events

Injection-related reactions (flu-like symptoms, mainly after the first dose). Local reactions at the injection site. Upper respiratory and urinary tract infections — more frequent but usually mild. Gradual decline in immunoglobulins (IgM, IgG) with prolonged use — monitored by lab work.

Serious but rare risks

- PML (progressive multifocal leukoencephalopathy): no cases have been reported with Kesimpta in clinical trials or post-marketing surveillance to date — significantly more favourable than natalizumab. As an anti-CD20 class drug, however, a theoretical risk remains, especially in patients previously exposed to natalizumab or fingolimod ([Novartis safety update 2024](https://www.novartis.com/us-en/sites/novartis_us/files/kesimpta.pdf)).

- Hepatitis B reactivation: HBsAg and anti-HBc must be screened before the first dose.

- Vaccines and COVID-19: the antibody response to vaccines is reduced (as with all anti-CD20 drugs), but T-cell responses are preserved. Vaccinate ideally 4–6 weeks BEFORE the next injection, so B cells have a chance to respond ([Sormani MP et al. eBioMedicine 2021](https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964%2821%2900425-X/fulltext)).

Pregnancy and breastfeeding

Ofatumumab is an IgG1 antibody that crosses the placenta, especially in the 2nd and 3rd trimester. Official guidance: contraception during therapy and for 6 months after the last dose. Real-world data from the Kesimpta pregnancy registry (Novartis MONITOR program and the GEM-MS registry) show no increase in malformations or complications in babies of mothers inadvertently exposed to ofatumumab ([Bove R et al., Mult Scler J 2024](https://journals.sagepub.com/doi/10.1177/13524585241226610)). Breastfeeding is likely safe because IgG is poorly absorbed from breast milk.

Kesimpta in Serbia — where it stands in 2026

Ofatumumab (Kesimpta) is registered with ALIMS (Serbia's medicines agency) and can be obtained in Serbia, but it is NOT yet on the RFZO Lista C for multiple sclerosis — meaning it is not 100% reimbursed by public insurance like Ocrevus, natalizumab, cladribine or the interferons ([RFZO Lista lekova](https://rfzo.rs/index.php/davalciusluga/lekovi-info/lekovi-lista)). In practice this means:

Patients eligible for high-efficacy therapy typically receive Ocrevus via the MS-centre committee. Kesimpta is currently used mainly through private purchase or individual access programmes (Novartis "compassionate use" for selected patients). RFZO negotiations and possible inclusion on Lista C are expected, especially given the growing use of Kesimpta across the EU.

Kesimpta is an attractive option for patients who cannot travel often for infusions (rural living, work, small children) or simply prefer self-administration at home — provided funding is in place.

Kesimpta compared with other DMTs

- vs Ocrevus (ocrelizumab): very similar efficacy (both reduce relapses by ~46–58%). The key difference is route of administration: Kesimpta = once-monthly home injection; Ocrevus = infusion every 6 months in hospital. Ocrevus is also approved for PPMS; Kesimpta is not.

- vs natalizumab (Tysabri): Kesimpta carries a lower PML risk and has no "rebound" on discontinuation, but natalizumab has a slightly faster onset of effect.

- vs fingolimod / siponimod (Gilenya / Mayzent): Kesimpta is more potent in active MS and does not require cardiac, eye, or CBC monitoring like the S1P modulators.

- vs cladribine (Mavenclad): Kesimpta requires continuous monthly use; Mavenclad is a short "induction" therapy with long drug-free intervals.

Practical tips for patients on Kesimpta

- Vaccinations: complete before the first dose (HBV, pneumococcus, flu, COVID-19, zoster if 50+). No live vaccines while on therapy.

- Storage: fridge at 2–8 °C; the pen can be out of the fridge for up to 7 days (up to 30 °C) when needed for travel.

- Injection diary: record the date and site of each injection; rotate sites (abdomen ↔ thigh ↔ upper arm) to avoid local reactions.

- Symptom diary: report any new symptom lasting >24 hours to your neurologist.

- Follow-up labs: CBC, IgM/IgG, liver tests every 6 months; brain MRI once a year.

- Travel: carry a treatment summary, a portable cool bag, and consult your neurologist about vaccines.

After 5+ years of clinical use, Kesimpta has confirmed itself as one of the most effective therapies for relapsing-remitting MS — with an efficacy profile comparable to Ocrevus, plus the practical advantage of once-monthly self-injection at home. It is not yet on Serbia's RFZO Lista C, which limits access, but reimbursement negotiations are expected. For patients who want high-efficacy B-cell therapy without being tied to a hospital — and who can secure funding — Kesimpta is one of the most attractive options in 2026.

Sources

Hauser SL et al. Ofatumumab versus Teriflunomide in Multiple Sclerosis (ASCLEPIOS I and II). NEJM 2020: https://www.nejm.org/doi/full/10.1056/NEJMoa1917246. Hauser SL et al. Long-term ofatumumab — ALITHIOS extension. Mult Scler J 2023. Cross AH et al. Five-year ALITHIOS update. AAN 2024. Bove R et al. Pregnancy outcomes on ofatumumab. Mult Scler J 2024. Sormani MP et al. Vaccine response on anti-CD20 in MS. eBioMedicine 2021. Novartis. FDA approval of Kesimpta, 20 Aug 2020: https://www.novartis.com/news/media-releases/novartis-receives-fda-approval-kesimpta-ofatumumab-first-and-only-self-administered-targeted-b-cell-therapy-relapsing-multiple-sclerosis. EMA EPAR — Kesimpta: https://www.ema.europa.eu/en/medicines/human/EPAR/kesimpta. RFZO Lista lekova: https://rfzo.rs/index.php/davalciusluga/lekovi-info/lekovi-lista. This article is educational, does not constitute medical advice and should not be the basis for changing therapy without consulting your MS-centre neurologist.