masitinib · program

Masitinib for Multiple sclerosis

Phase 3SuspendedAB Science (AB)

Indications for masitinib: Amyotrophic lateral sclerosis · Phase 3 Multiple sclerosis · Phase 3 Alzheimer's disease · Phase 3

Masitinib for primary progressive MS (PPMS) and non-active secondary progressive MS (nSPMS) - a neuroimmune (mast cell + microglia) approach to relapse-independent progression. The pivotal Phase 3 AB07002 (n=611 randomized, 96 weeks, 20 countries) was positive: masitinib 4.5 mg/kg/day significantly reduced overall EDSS deterioration vs placebo (between-group difference -0.097, 97% CI -0.192 to -0.002, p=0.0256; Class II evidence), while the independent uptitrated 6.0 mg/kg/day group was inconclusive; results were published in Neurology Neuroimmunology & Neuroinflammation in February 2022. The confirmatory Phase 3 AB20009 (MAXIMS; target 800 patients, masitinib 4.5 mg/kg/day vs placebo, 96-week confirmed-progression primary endpoint) was authorized by ANSM (January 2022), the Swedish MPA (February 2022) and FDA (December 2022) and started June 2022 - but recruitment was voluntarily halted with all AB Science European studies in April 2026, and on 10 July 2026 AB Science discontinued the trial outright (explicitly not for safety reasons) to focus resources on ALS and AML. The company states that Phase 3 development in MS is to be pursued through partnerships, as the indication requires commercial capabilities it does not possess; the program is therefore recorded as suspended pending a partner rather than discontinued. AB Science continues to invest in MS intellectual property (Japanese method-of-use patent to February 2041, granted January 2026). EMA has never reviewed masitinib in MS; the 2018 and 2024 EU refusals concern ALS only.

Data current as of

Development timeline

Phase 3Aug 2011 – Jul 2026
  1. AB Science discontinued the AB20009 (MAXIMS) trial - one of three non-priority studies terminated ('no prospect of a rapid resumption'; explicitly not related to any safety concern; the company intends to close the studies out per regulations). The MS *program* is kept as suspended, not discontinued: the sponsor's stated position (April/May 2026) is that MS Phase 3 development will be pursued through partnerships. Flip to discontinued if no partner materializes.↗
  2. Trial terminatedAB Science discontinues the Phase 3 MAXIMS trial (AB20009) in progressive MS↗
  3. New-patient recruitment voluntarily halted across AB Science's European studies during a strategic reorganization (European authorities had questioned the company's resources/structure for running EU trials). Strategic priorities announced the same day: focus on ALS Phase 3 + AB8939 AML; 'continuation, via partnerships, of Phase III development in multiple sclerosis and Alzheimer's disease'. CT.gov flipped NCT05441488 to SUSPENDED on 2026-05-06.↗
  4. Trial suspendedMAXIMS recruitment halted in AB Science's Europe-wide voluntary suspension↗
  5. Patent grantedJapan grants method-of-use patent for masitinib in progressive MS (protection to February 2041)↗
  6. Confirmatory Phase 3 AB20009 (MAXIMS, NCT05441488) started per ClinicalTrials.gov actual start date: masitinib titrated to 4.5 mg/kg/day vs placebo, target 800 patients with primary progressive or non-active secondary progressive MS, primary endpoint time to confirmed progression over 96 weeks.
  7. Trial startedConfirmatory Phase 3 MAXIMS (AB20009) starts in progressive MS
  8. metAB07002 Phase 2b/3 topline (2020-02-20): masitinib 4.5 mg/kg/day met the primary endpoint in progressive MS, significantly reducing overall EDSS deterioration vs placebo (published value: between-group difference -0.097, 97% CI -0.192 to -0.002, p=0.0256); the independent uptitrated 6.0 mg/kg/day group was inconclusive.↗
  9. Pivotal Phase 3 (AB Science: 'Phase 2b/3') AB07002 started - first participant randomized 2011-08-25 per the trial publication (CT.gov start August 2011): masitinib 4.5 mg/kg/day or 4.5-to-6.0 titrated vs matched placebo (2:1, two independent parallel groups), 96 weeks, PPMS or relapse-free SPMS, primary endpoint overall EDSS change (GEE, W12-W96).↗
Phase 2Jul 2007
  1. Exploratory Phase 2a AB04011 (NCT01450488, n=35): oral masitinib 3 or 6 mg/kg/day in primary progressive or relapse-free secondary progressive MS; primary completion July 2007 (study completion 2010-01). Registered retrospectively in 2011.

Readouts

  • 2020-02-20ReportedTopline datametNCT01433497

    AB07002 Phase 2b/3 topline (2020-02-20): masitinib 4.5 mg/kg/day met the primary endpoint in progressive MS, significantly reducing overall EDSS deterioration vs placebo (published value: between-group difference -0.097, 97% CI -0.192 to -0.002, p=0.0256); the independent uptitrated 6.0 mg/kg/day group was inconclusive. ↗

Clinical trials in Multiple sclerosis

NCT05441488AB20009Phase 3Discontinuedn=800

MAXIMS: Masitinib Dose Titration to 4.5 mg/kg/day Versus Placebo in the Treatment of Patients With Primary Progressive or Non-active Secondary Progressive Multiple Sclerosis (96 weeks, target n=800)

Started Jun 2022· Primary completion Dec 2028· 📍 37 sites across 8 countries (France, Poland, Spain, Greece)

NCT01433497AB07002Phase 3Completedn=656

Efficacy and Safety of Masitinib 4.5 mg/kg/day Versus Placebo in the Treatment of Patients With Primary Progressive or Relapse-free Secondary Progressive Multiple Sclerosis (96 weeks)

Started Aug 2011· Primary completion Sept 2019· 📍 8 sites across 7 countries (France, Spain, Bulgaria, Germany)

NCT01450488AB04011Phase 2Completedn=35

Masitinib in Primary Progressive Multiple Sclerosis or Relapse-free Secondary Progressive Multiple Sclerosis (Phase 2a, AB1010 at 2 dose levels)

Started Jun 2005· Primary completion Jul 2007

Formulations

FormulationRouteRegimenPharmacokinetics
Masitinib (mesylate) oral tablet, weight-based twice-daily dosing
Weight-based daily dose given orally as two intakes. Alzheimer's disease: AB09004 tested 4.5 mg/kg/day and 4.5 titrated to 6.0 mg/kg/day after 12 weeks (plus a 3.0 mg/kg/day arm), always as add-on to cholinesterase inhibitor and/or memantine; confirmatory AB21004 planned 3.0 mg/kg/day escalated to 4.5 mg/kg/day after 4 weeks as add-on to standard of care.
OralTwice daily—

Mechanism of action (compound-wide)

Orally bioavailable, selective tyrosine kinase inhibitor targeting wild-type and juxtamembrane-mutant KIT (c-Kit), PDGFR alpha and beta, and the Src-family kinase Lyn, with weak activity against Abl and Src and no significant inhibition of most other kinases screened (Dubreuil et al., PLoS ONE 2009: recombinant-enzyme IC50 0.20 uM for wild-type KIT vs >10 uM for FGFR3 and FAK). In Alzheimer's disease the proposed mechanism is modulation of the innate neuroimmune system - mast cells (via KIT) and microglia (via Lyn-family kinases) - as an adjunct to symptomatic standard of care (cholinesterase inhibitors and/or memantine), per the AB09004 trial report (Dubois et al., Alzheimer's Research & Therapy 2023).

TargetActionAffinity
KITprimaryKITInhibitorIC50 200 nMⓘ
LynLYNInhibitorIC50 510 nMⓘ
PDGFR-alphaPDGFRAInhibitorIC50 540 nMⓘ
PDGFR-betaPDGFRBInhibitorIC50 800 nMⓘ

← Full masitinib compound page (identity, identifiers, all indications)

Sources

  1. AB Science clinical program update: focus on ALS + AML; AB21004 not among the discontinued studies (2026-07-10) — AB Science SA
  2. AB Science provides an update on its clinical program: voluntary temporary halt of European trials; Alzheimer's (and MS) Phase 3 development to continue via partnerships (2026-04-16) — AB Science SA
  3. AB Science receives Japanese patent protection for the use of masitinib in progressive forms of multiple sclerosis until 2041 (JP 7788154) (2026-01-21) — AB Science SA
  4. Dubreuil P, et al. Masitinib (AB1010), a potent and selective tyrosine kinase inhibitor targeting KIT. PLoS ONE. 2009;4(9):e7258 — PLoS ONE via PubMed Central
  5. NCT01433497 (AB07002) - Efficacy and Safety of Masitinib in the Treatment of Progressive Multiple Sclerosis (Phase 3, n=656, completed; primary completion 2019-09) — ClinicalTrials.gov (U.S. National Library of Medicine)
  6. NCT01450488 (AB04011) - Masitinib in Primary Progressive or Relapse-free Secondary Progressive MS (Phase 2a, n=35, completed) — ClinicalTrials.gov (U.S. National Library of Medicine)
  7. NCT01872598 (AB09004) - Masitinib in Patients With Mild to Moderate Alzheimer's Disease (Phase 3, n=721, completed 2020-12) — ClinicalTrials.gov (U.S. National Library of Medicine)
  8. NCT05441488 (AB20009, MAXIMS) - Masitinib vs Placebo in Primary Progressive or Non-active Secondary Progressive MS (Phase 3, target n=800; registry status SUSPENDED as of 2026-05-06) — ClinicalTrials.gov (U.S. National Library of Medicine)
  9. Positive top-line Phase 2b/3 results for masitinib in progressive forms of MS (AB07002) (2020-02-20) — AB Science SA
  10. Vermersch P, et al. Efficacy and Safety of Masitinib in Progressive Forms of Multiple Sclerosis: A Randomized, Phase 3, Clinical Trial. Neurol Neuroimmunol Neuroinflamm. 2022;9(3):e1148 (PMC9005047) — Neurology Neuroimmunology & Neuroinflammation (AAN/Wolters Kluwer) / PubMed