Small Molecule · masitinib

Masitinib

Phase 3AB Science (AB)
  • EU Orphan Designation For ALS (Referenced In The EMA Alsitek Refusal Q&A); Swissmedic Orphan Drug Status For ALS (2022-12-27, Per AB Science)

Oral tyrosine kinase inhibitor (AB1010) developed by AB Science (Paris; Euronext: AB), selectively targeting KIT (c-Kit), PDGFR alpha/beta and the Src-family kinase Lyn. Its CNS rationale is neuroimmune: by inhibiting KIT-dependent mast cells and Lyn/Fyn-dependent microglia it aims to slow neuroinflammation-driven neurodegeneration. Amyotrophic lateral sclerosis is the lead indication: the Phase 2/3 AB10015 study was positive in its prespecified 'normal progressor' population, but two EU marketing applications were refused (Alsitek, 2018; a conditional MAA refused on re-examination in October 2024), and a new confirmatory Phase 3 (AB23005) was authorized by FDA and initial EU countries in 2025. Phase 3 studies in progressive multiple sclerosis (AB07002) and mild-to-moderate Alzheimer's disease (AB09004) each reported significant primary-endpoint benefit at 4.5 mg/kg/day, but as of April-July 2026 AB Science has refocused on ALS (plus AB8939 in AML), discontinued the confirmatory MS trial and stated MS and Alzheimer's development will only continue through partnerships. Also developed in non-CNS indications (mastocytosis, severe asthma, oncology), largely deprioritized or discontinued. Masitinib is approved in veterinary medicine as Masivet (EU, 2008) for canine mast cell tumours.

Also known as: masitinib, AB1010, AB 1010, masitinib mesylate, Alsitek, Masivet, 790299-79-5, 4-[(4-methylpiperazin-1-yl)methyl]-N-[4-methyl-3-[(4-pyridin-3-yl-1,3-thiazol-2-yl)amino]phenyl]benzamide

Data current as of

Key facts

Modality
Small molecule
Chemical class
benzamide, piperazine, pyridine, thiazole
Chemistry
Achiral
Mechanism
KIT inhibitor
Highest phase
Phase 3
Lead indication
Amyotrophic lateral sclerosis
Developer
AB Science (AB)
Designations
EU Orphan Designation For ALS (Referenced In The EMA Alsitek Refusal Q&A); Swissmedic Orphan Drug Status For ALS (2022-12-27, Per AB Science)
Trials
9 tracked · 1 recruiting · 118 sites
Next catalyst
December 2027 — Registry results (Amyotrophic lateral sclerosis)

Mechanism of action#

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).

100 nM1 µMKITKIT — inhibitor — IC50 200 nMIC50 200 nMLynLyn — inhibitor — IC50 510 nMIC50 510 nMPDGFR-alphaPDGFR-alpha — inhibitor — IC50 540 nMIC50 540 nMPDGFR-betaPDGFR-beta — inhibitor — IC50 800 nMIC50 800 nM
Binding affinity on a log scale — further left is more potent. Values from the sourced literature (see table).
TargetActionAffinity
KITprimaryKITInhibitorIC50 200 nMⓘ
LynLYNInhibitorIC50 510 nMⓘ
PDGFR-alphaPDGFRAInhibitorIC50 540 nMⓘ
PDGFR-betaPDGFRBInhibitorIC50 800 nMⓘ

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—

Development timeline#

2010201520202025TodayPhase 21 Jul 2008 — phase change — Exploratory Phase 2 AB04024 (NCT00976118, n=34): oral masitinib 3 or 6 mg/kg/day vs placebo as adjunct in mild-to-moderate AD; primary completion July 2008 (ADAS-Cog at week 24). Published as Piette et al., Alzheimers Res Ther 2011.1 Jul 2007 — phase change — 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.Phase 331 Dec 2027 — upcoming — ClinicalTrials.gov estimated primary completion of confirmatory Phase 3 AB19001 (NCT03127267): December 2027 (registry estimate, not company guidance).10 Jul 2026 — phase change — 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.10 Jul 2026 — Trial terminated — AB Science discontinues the Phase 3 MAXIMS trial (AB20009) in progressive MS16 Apr 2026 — phase change — 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 2026-05-06.16 Apr 2026 — phase change — AB Science deprioritized Alzheimer's disease in its strategic reorganization: new-patient recruitment voluntarily halted across its European studies, internal resources focused on ALS Phase 3 + AB8939 AML, and 'continuation, via partnerships, of Phase III development in multiple sclerosis and Alzheimer's disease, indications requiring commercial capabilities that AB Science does not possess in-house' (restated in the 2026-05-13 annual results). AB21004 had still not started and was not among the trials formally discontinued on 2026-07-10. Program suspended pending a partner; flip to discontinued if the sponsor abandons the indication.16 Apr 2026 — Trial suspended — MAXIMS recruitment halted in AB Science's Europe-wide voluntary suspension16 Apr 2026 — Financing — EUR 25M clinical-trial-failure insurance secured for the ALS Phase 3 (AB23005)21 Jan 2026 — Patent granted — Japan grants method-of-use patent for masitinib in progressive MS (protection to February 2041)16 Sept 2025 — Trial registered — New confirmatory Phase 3 AB23005 registered on ClinicalTrials.gov (NCT07174492)17 Oct 2024 — phase change — CHMP confirmed its negative opinion on the conditional MAA after re-examination (initial negative opinion 2024-06-27); the EU filing is closed and the program reverts to confirmatory Phase 3. The agreed path forward is the new confirmatory study AB23005 (FDA + first EU authorizations announced 2025-07-24; registered as NCT07174492 on 2025-09-16; per the 2026-07-10 update it has not yet begun and will start after a substantial protocol amendment is re-authorized). Health Canada had issued a Notice of Non-compliance-Withdrawal on 2024-02-26 (reconsideration eligibility granted 2024-04-03).17 Oct 2024 — CHMP opinion — CHMP confirms refusal of masitinib conditional MAA in ALS after re-examination3 Oct 2022 — Trial registered — Confirmatory Phase 3 AB21004 in mild Alzheimer's disease registered (NCT05564169) - never started28 Jun 2022 — phase change — 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.28 Jun 2022 — Trial started — Confirmatory Phase 3 MAXIMS (AB20009) starts in progressive MS2 Feb 2021 — phase change — Confirmatory Phase 3 AB19001 (NCT03127267) actual start date per ClinicalTrials.gov: masitinib 4.5 or 6.0 mg/kg/day + riluzole vs placebo + riluzole, 48-week ALSFRS-R primary endpoint. Context: AB10015 had completed (primary completion 2016-12-05) and the first EU MAA (Alsitek) had been refused in 2018. Note: a company-wide voluntary hold on masitinib studies ran 2021-06-01 until resumption authorizations later in 2021 (FDA authorized resuming AB19001 enrollment on 2021-11-18).16 Dec 2020 — readout (met) — AB09004 topline (2020-12-16): masitinib 4.5 mg/kg/day met the ADAS-cog primary endpoint in mild-to-moderate Alzheimer's disease as add-on to standard of care (published values: between-group difference -2.15, 97.5% CI -3.48 to -0.81, p<0.001; ADCS-ADL co-primary difference +1.82, p=0.038); the independent titrated 6.0 mg/kg/day group was inconclusive.20 Feb 2020 — readout (met) — 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.1 Jan 2012 — phase change — Pivotal AB09004 (NCT01872598) started per ClinicalTrials.gov (January 2012, month precision): randomized, double-blind, placebo-controlled, four-arm study of masitinib 4.5 mg/kg/day, 4.5-to-6.0 titrated, and (initially) 3.0 mg/kg/day vs placebo, as add-on to cholinesterase inhibitor and/or memantine in mild-to-moderate AD; co-primary ADAS-Cog and ADCS-ADL at week 24. Registered PHASE3; AB Science communicates it as 'Phase 2b/3'.25 Aug 2011 — phase change — 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 2/37 Jul 2019 — readout (met) — AB10015 Phase 2/3 published (Mora et al., ALS-FTD 2020, epub 2019-07-07): in the prespecified primary population (normal progressors, ALSFRS-R decline <1.1 pts/month), masitinib 4.5 mg/kg/day + riluzole slowed 48-week ALSFRS-R decline by 3.4 points vs placebo (95% CI 0.65-6.13, p=0.016; 27% slowing), with significant ALSAQ-40, FVC and time-to-event secondaries; no effect in the broader population or 3.0 mg/kg/day cohorts.18 Apr 2018 — CHMP opinion — CHMP adopts negative opinion on Alsitek (masitinib), the first EU marketing application in ALS1 Apr 2013 — phase change — AB10015 (NCT02588677) start per ClinicalTrials.gov (April 2013, month precision): randomized, double-blind, placebo-controlled Phase 2/3 of masitinib 3.0 or 4.5 mg/kg/day + riluzole vs placebo + riluzole in 394 ALS patients, with a blinded Phase 2 -> Phase 2/3 transition and a prospectively-declared primary population of 'normal progressors' on 4.5 mg/kg/day.Filed (NDA)27 Jun 2024 — CHMP opinion — CHMP adopts negative opinion on the conditional marketing authorisation of masitinib in ALS24 Aug 2022 — phase change — AB Science filed an application for conditional marketing authorization to the EMA for masitinib in ALS (based on AB10015 plus long-term survival follow-up), while confirmatory AB19001 continued. A Health Canada NDS was also under review in this period (filing authorized 2022-02-21; Notice of Deficiency 2022-12-13).24 Aug 2022 — NDA/BLA filed — AB Science files EU conditional marketing authorisation application for masitinib in ALS
Phase change Readout Event UpcomingHover a marker for details.
Phase 3Aug 2011 – Dec 2027
  1. UpcomingClinicalTrials.gov estimated primary completion of confirmatory Phase 3 AB19001 (NCT03127267): December 2027 (registry estimate, not company guidance).Amyotrophic lateral sclerosis
  2. 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.Multiple sclerosis↗
  3. Trial terminatedAB Science discontinues the Phase 3 MAXIMS trial (AB20009) in progressive MSMultiple sclerosis↗
  4. 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.Multiple sclerosis↗
  5. AB Science deprioritized Alzheimer's disease in its strategic reorganization: new-patient recruitment voluntarily halted across its European studies, internal resources focused on ALS Phase 3 + AB8939 AML, and 'continuation, via partnerships, of Phase III development in multiple sclerosis and Alzheimer's disease, indications requiring commercial capabilities that AB Science does not possess in-house' (restated in the 2026-05-13 annual results). AB21004 had still not started and was not among the trials formally discontinued on 2026-07-10. Program suspended pending a partner; flip to discontinued if the sponsor abandons the indication.Alzheimer's disease↗
  6. Trial suspendedMAXIMS recruitment halted in AB Science's Europe-wide voluntary suspensionMultiple sclerosis↗
  7. FinancingEUR 25M clinical-trial-failure insurance secured for the ALS Phase 3 (AB23005)Amyotrophic lateral sclerosis↗
  8. Patent grantedJapan grants method-of-use patent for masitinib in progressive MS (protection to February 2041)Multiple sclerosis↗
  9. Trial registeredNew confirmatory Phase 3 AB23005 registered on ClinicalTrials.gov (NCT07174492)Amyotrophic lateral sclerosis
  10. CHMP confirmed its negative opinion on the conditional MAA after re-examination (initial negative opinion 2024-06-27); the EU filing is closed and the program reverts to confirmatory Phase 3. The agreed path forward is the new confirmatory study AB23005 (FDA + first EU authorizations announced 2025-07-24; registered as NCT07174492 on 2025-09-16; per the 2026-07-10 update it has not yet begun and will start after a substantial protocol amendment is re-authorized). Health Canada had issued a Notice of Non-compliance-Withdrawal on 2024-02-26 (reconsideration eligibility granted 2024-04-03).Amyotrophic lateral sclerosis↗
  11. CHMP opinionCHMP confirms refusal of masitinib conditional MAA in ALS after re-examinationAmyotrophic lateral sclerosis↗
  12. Trial registeredConfirmatory Phase 3 AB21004 in mild Alzheimer's disease registered (NCT05564169) - never startedAlzheimer's disease
  13. 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.Multiple sclerosis
  14. Trial startedConfirmatory Phase 3 MAXIMS (AB20009) starts in progressive MSMultiple sclerosis
  15. Confirmatory Phase 3 AB19001 (NCT03127267) actual start date per ClinicalTrials.gov: masitinib 4.5 or 6.0 mg/kg/day + riluzole vs placebo + riluzole, 48-week ALSFRS-R primary endpoint. Context: AB10015 had completed (primary completion 2016-12-05) and the first EU MAA (Alsitek) had been refused in 2018. Note: a company-wide voluntary hold on masitinib studies ran 2021-06-01 until resumption authorizations later in 2021 (FDA authorized resuming AB19001 enrollment on 2021-11-18).Amyotrophic lateral sclerosis
  16. metAB09004 topline (2020-12-16): masitinib 4.5 mg/kg/day met the ADAS-cog primary endpoint in mild-to-moderate Alzheimer's disease as add-on to standard of care (published values: between-group difference -2.15, 97.5% CI -3.48 to -0.81, p<0.001; ADCS-ADL co-primary difference +1.82, p=0.038); the independent titrated 6.0 mg/kg/day group was inconclusive.Alzheimer's disease↗
  17. 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.Multiple sclerosis↗
  18. Pivotal AB09004 (NCT01872598) started per ClinicalTrials.gov (January 2012, month precision): randomized, double-blind, placebo-controlled, four-arm study of masitinib 4.5 mg/kg/day, 4.5-to-6.0 titrated, and (initially) 3.0 mg/kg/day vs placebo, as add-on to cholinesterase inhibitor and/or memantine in mild-to-moderate AD; co-primary ADAS-Cog and ADCS-ADL at week 24. Registered PHASE3; AB Science communicates it as 'Phase 2b/3'.Alzheimer's disease
  19. 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).Multiple sclerosis↗
Filed (NDA)Aug 2022 – Jun 2024
  1. CHMP opinionCHMP adopts negative opinion on the conditional marketing authorisation of masitinib in ALSAmyotrophic lateral sclerosis↗
  2. AB Science filed an application for conditional marketing authorization to the EMA for masitinib in ALS (based on AB10015 plus long-term survival follow-up), while confirmatory AB19001 continued. A Health Canada NDS was also under review in this period (filing authorized 2022-02-21; Notice of Deficiency 2022-12-13).Amyotrophic lateral sclerosis↗
  3. NDA/BLA filedAB Science files EU conditional marketing authorisation application for masitinib in ALSAmyotrophic lateral sclerosis↗
Phase 2/3Apr 2013 – Jul 2019
  1. metAB10015 Phase 2/3 published (Mora et al., ALS-FTD 2020, epub 2019-07-07): in the prespecified primary population (normal progressors, ALSFRS-R decline <1.1 pts/month), masitinib 4.5 mg/kg/day + riluzole slowed 48-week ALSFRS-R decline by 3.4 points vs placebo (95% CI 0.65-6.13, p=0.016; 27% slowing), with significant ALSAQ-40, FVC and time-to-event secondaries; no effect in the broader population or 3.0 mg/kg/day cohorts.Amyotrophic lateral sclerosis↗
  2. CHMP opinionCHMP adopts negative opinion on Alsitek (masitinib), the first EU marketing application in ALSAmyotrophic lateral sclerosis↗
  3. AB10015 (NCT02588677) start per ClinicalTrials.gov (April 2013, month precision): randomized, double-blind, placebo-controlled Phase 2/3 of masitinib 3.0 or 4.5 mg/kg/day + riluzole vs placebo + riluzole in 394 ALS patients, with a blinded Phase 2 -> Phase 2/3 transition and a prospectively-declared primary population of 'normal progressors' on 4.5 mg/kg/day.Amyotrophic lateral sclerosis
Phase 2Jul 2007 – Jul 2008
  1. Exploratory Phase 2 AB04024 (NCT00976118, n=34): oral masitinib 3 or 6 mg/kg/day vs placebo as adjunct in mild-to-moderate AD; primary completion July 2008 (ADAS-Cog at week 24). Published as Piette et al., Alzheimers Res Ther 2011.Alzheimer's disease
  2. 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.Multiple sclerosis

Masitinib for Amyotrophic lateral sclerosis#

Phase 3ActiveAmyotrophic lateral sclerosis indication →

Masitinib, an oral KIT/PDGFR/Lyn tyrosine kinase inhibitor targeting mast cells and microglia, as add-on to riluzole in amyotrophic lateral sclerosis - AB Science's lead indication and, since April 2026, one of its only two priority programs. The Phase 2/3 AB10015 study (n=394) met its prespecified primary analysis: in 'normal progressors' (ALSFRS-R decline <1.1 points/month pre-baseline), masitinib 4.5 mg/kg/day slowed 48-week ALSFRS-R decline by 3.4 points vs placebo (27% slowing, p=0.016), with convergent sensitivity analyses and a long-term median overall survival benefit of over 2 years in follow-up analyses. Regulatory history is chequered: the first EU application (Alsitek) was refused in 2018 (arbitrary subgrouping, site-inspection and data-handling concerns per CHMP); a second, conditional MAA filed August 2022 received a CHMP negative opinion on 27 June 2024, confirmed on re-examination 17 October 2024 (subgroup-reliability concerns); Health Canada issued a Notice of Non-compliance-Withdrawal in February 2024 (reconsideration eligibility granted April 2024). The path forward agreed with regulators is a new confirmatory Phase 3, AB23005 (n=408, 1:1, masitinib 4.5 mg/kg/day + riluzole vs placebo + riluzole, 48-week ALSFRS-R primary endpoint, enrolling only normal progressors without complete loss of function, edaravone allowed as a stratification factor) - authorized by FDA and by the first EU countries (Spain, Greece, Slovenia, via CTIS) as announced 2025-07-24, registered as NCT07174492 in September 2025, and de-risked by a EUR 25M (extendable to EUR 39M) clinical-trial-failure insurance policy from Lloyd's Syndicate 1902 (binding offer, April 2026, activatable until 2026-12-31). As of 2026-07-10 AB23005 had not yet dosed: AB Science is submitting a substantial protocol amendment and will re-seek authorization to start. The earlier confirmatory Phase 3 AB19001 (started 2021, 495 planned) remains registry-listed as recruiting but has been effectively superseded by AB23005 and is subject to the April 2026 voluntary halt of European recruitment.

Readouts

  • December 2027AnticipatedRegistry resultsNCT03127267

    ClinicalTrials.gov estimated primary completion of confirmatory Phase 3 AB19001 (NCT03127267): December 2027 (registry estimate, not company guidance).

  • 2019-07-07ReportedFull resultsmetNCT02588677

    AB10015 Phase 2/3 published (Mora et al., ALS-FTD 2020, epub 2019-07-07): in the prespecified primary population (normal progressors, ALSFRS-R decline <1.1 pts/month), masitinib 4.5 mg/kg/day + riluzole slowed 48-week ALSFRS-R decline by 3.4 points vs placebo (95% CI 0.65-6.13, p=0.016; 27% slowing), with significant ALSAQ-40, FVC and time-to-event secondaries; no effect in the broader population or 3.0 mg/kg/day cohorts. ↗

Masitinib for Multiple sclerosis#

Phase 3SuspendedMultiple sclerosis indication →

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.

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. ↗

Masitinib for Alzheimer's disease#

Phase 3SuspendedAlzheimer's disease indication →

Masitinib as an adjunct to cholinesterase inhibitors and/or memantine in mild-to-moderate Alzheimer's disease - a neuroimmune (mast cell + microglia) approach distinct from the amyloid pathway. The pivotal AB09004 study (Phase 3 per registry; a four-arm 'Phase 2b/3' per AB Science; 721 registered, ~635 analyzed across the two independent parallel groups) reported a positive result in December 2020, published in Alzheimer's Research & Therapy in February 2023: masitinib 4.5 mg/kg/day significantly improved ADAS-cog vs placebo at week 24 (between-group difference -2.15, 97.5% CI -3.48 to -0.81, p<0.001), with the ADCS-ADL co-primary difference +1.82 (97.5% CI -0.15 to 3.79, p=0.038); the independent titrated 6.0 mg/kg/day group was inconclusive. A confirmatory Phase 3, AB21004 (target 600 patients with MILD AD on stable standard of care, primary endpoint iADRS change at week 24), received its first agency authorizations in October 2022 and FDA authorization in November 2022 - but has never started: the registration (NCT05564169) remains not-yet-recruiting with a stale estimated start of June 2026. In April 2026 AB Science deprioritized the indication, stating Alzheimer's (like MS) requires commercial capabilities it lacks and that its Phase 3 development will be 'pursued through partnerships', while focusing internal resources on ALS and AML; unlike the MS trial, AB21004 was not among the studies formally discontinued in July 2026. The program is recorded as suspended pending a partner. EMA has never reviewed masitinib in Alzheimer's disease.

Readouts

  • 2020-12-16ReportedTopline datametNCT01872598

    AB09004 topline (2020-12-16): masitinib 4.5 mg/kg/day met the ADAS-cog primary endpoint in mild-to-moderate Alzheimer's disease as add-on to standard of care (published values: between-group difference -2.15, 97.5% CI -3.48 to -0.81, p<0.001; ADCS-ADL co-primary difference +1.82, p=0.038); the independent titrated 6.0 mg/kg/day group was inconclusive. ↗

Clinical trials#

NCT05564169AB21004Phase 3Activen=600

Masitinib as Add-on Therapy in Patients With Mild Alzheimer's Disease Treated With Standard of Care (confirmatory Phase 3, iADRS at week 24, target n=600)

Started Jun 2026· Primary completion Dec 2028· 9 sites across 2 countries

SpainFrance

NCT07174492AB23005Phase 3Activen=412

Efficacy and Safety of Masitinib in Combination With SoC Versus Placebo in Combination With SoC in the Treatment of ALS (confirmatory Phase 3, n=408)

Started Jan 2026· Primary completion Dec 2028· 1 site across 1 country

Greece

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

FrancePolandSpainGreece

NCT03127267AB19001Phase 3Recruitingn=495

Efficacy and Safety of Masitinib Versus Placebo in the Treatment of ALS Patients (masitinib 4.5 or 6.0 mg/kg/day + riluzole)

Started Feb 2021· Primary completion Dec 2027· 56 sites across 17 countries

FranceItalySpainUnited States

NCT02588677AB10015Phase 2/3Completedn=394

Masitinib in Combination With Riluzole for the Treatment of Patients Suffering From Amyotrophic Lateral Sclerosis (ALS)

Started Apr 2013· Primary completion Dec 2016· 1 site across 1 country

Spain

Show all 9 trials

NCT01872598AB09004Phase 3Completedn=721

Masitinib in Patients With Mild to Moderate Alzheimer's Disease (four-arm, add-on to cholinesterase inhibitor and/or memantine; co-primary ADAS-Cog and ADCS-ADL at week 24)

Started Jan 2012· Primary completion Dec 2020· 6 sites across 6 countries

GreeceRomaniaPolandUkraine

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

FranceSpainBulgariaGermany

NCT00976118AB04024Phase 2Completedn=34

Activity of Masitinib (AB1010) in Mild to Moderate Alzheimer's Disease (adjunct to standard of care, ADAS-Cog at week 24)

Started Feb 2006· Primary completion Jul 2008

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

Sources#

  1. AB Science announces that it has filed an application for conditional marketing authorization to EMA for masitinib in the treatment of ALS (2022-08-24) — AB Science SA
  2. AB Science clinical program update: focus on ALS + AML; AB21004 not among the discontinued studies (2026-07-10) — AB Science SA
  3. 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
  4. AB Science provides an update on the application for conditional marketing authorisation of masitinib in ALS - CHMP negative opinion (2024-06-28) — AB Science SA
  5. AB Science provides an update on the application for conditional marketing authorisation of masitinib in ALS - refusal confirmed after re-examination (2024-10-17) — AB Science SA
  6. 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
  7. Alsitek (masitinib) - EPAR: CHMP negative opinion 2018-04-18; re-examination request withdrawn; marketing authorisation refused 2018-07-26 — European Medicines Agency
  8. 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
  9. Mora JS, et al. Masitinib as an add-on therapy to riluzole in patients with amyotrophic lateral sclerosis: a randomized clinical trial. Amyotroph Lateral Scler Frontotemporal Degener. 2020;21(1-2):5-14 (epub 2019-07-07) — Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration (Taylor & Francis) / PubMed
  10. NCT00976118 (AB04024) - Activity of Masitinib (AB1010) in Mild to Moderate Alzheimer's Disease (Phase 2, n=34, completed) — ClinicalTrials.gov (U.S. National Library of Medicine)
Show all 21 sources
  1. 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)
  2. 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)
  3. 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)
  4. NCT02588677 (AB10015) - Masitinib in Combination With Riluzole for the Treatment of Patients Suffering From ALS (Phase 2/3, n=394, completed) — ClinicalTrials.gov (U.S. National Library of Medicine)
  5. NCT03127267 (AB19001) - Efficacy and Safety of Masitinib Versus Placebo in the Treatment of ALS Patients (Phase 3, est. n=495, recruiting; last update 2025-09-12) — ClinicalTrials.gov (U.S. National Library of Medicine)
  6. 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)
  7. NCT05564169 (AB21004) - Masitinib as Add-on Therapy in Patients With Mild Alzheimer's Disease (confirmatory Phase 3, target n=600, not yet recruiting; last update 2025-10-03) — ClinicalTrials.gov (U.S. National Library of Medicine)
  8. NCT07174492 (AB23005) - Efficacy and Safety of Masitinib in Combination With SoC Versus Placebo in ALS (confirmatory Phase 3, est. n=412, not yet recruiting) — ClinicalTrials.gov (U.S. National Library of Medicine)
  9. Positive confirmatory Phase 2b/3 study AB09004 with masitinib in Alzheimer's disease (2020-12-16) — AB Science SA
  10. Positive top-line Phase 2b/3 results for masitinib in progressive forms of MS (AB07002) (2020-02-20) — AB Science SA
  11. 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