Emerging Drugs in Trials for MND and PLS

The drug pipeline for motor neuron disease is broader in 2026 than at any previous point. Dozens of compounds are in active clinical trials targeting a range of biological mechanisms. None are approved for PLS. Most are studied primarily in ALS. This page covers every drug with meaningful clinical evidence or active trial activity, with honest assessment of what the data shows and how relevant each one might be for people with PLS.

QRL-101 — Potassium channel opener for motor neuron hyperexcitability

Developer: Quralis  |  Mechanism: Opens Kv7.2/7.3 potassium ion channels to reduce motor neuron hyperexcitability  |  Stage: Phase 1 completed; Phase 2 planned  |  Evidence level: Emerging

Upper motor neuron hyperexcitability — the abnormal tendency of motor neurons to fire too readily — is present in both ALS and PLS, and is one of the few disease mechanisms that directly connects the two conditions. QRL-101 targets this mechanism by opening Kv7.2/7.3 potassium channels, which regulate how easily nerve cells fire. When these channels are faulty or underactive, neurons fire excessively. QRL-101 corrects this by increasing potassium channel activity and damping hyperexcitability.

The connection to TDP-43 pathology is significant: TDP-43 protein, which mislocalizes in approximately 97% of ALS cases, causes errors in the production of Kv7.2/7.3 channels, resulting in faulty channels and overactive neurons. QRL-101 is designed to compensate for this.

A Phase 1 trial (NCT06714396) in 12 adults with ALS showed that QRL-101 reduced nerve cell excitability compared to placebo, consistent with earlier Phase 1 results in healthy volunteers. The drug showed a favorable safety profile. Quralis is planning a Phase 2 proof-of-concept trial. Motor neuron hyperexcitability is present in approximately 50% of ALS patients, is associated with faster progression and shorter survival, and is also a documented feature of PLS — which makes QRL-101 one of the more mechanistically relevant pipeline drugs for the PLS population, even though no PLS-specific data exist.

Pridopidine — Sigma-1 receptor activator

Developer: Prilenia Therapeutics / Ferrer  |  Mechanism: Sigma-1 receptor (S1R) agonism, supporting cellular processes relevant to motor neuron survival  |  Stage: Phase 3 PREVAiLS trial enrolling  |  Evidence level: Emerging

Pridopidine activates the sigma-1 receptor, a protein in the endoplasmic reticulum that regulates calcium signaling, mitochondrial function, and cellular stress responses — pathways implicated in motor neuron degeneration. The drug is an oral daily tablet.

In the HEALEY ALS Platform Trial (NCT04297683), the pridopidine arm failed its primary endpoint for the overall enrolled population. However, a pre-specified subgroup analysis of 284 participants with early, rapidly progressive ALS showed a 32% slowing of ALSFRS-R decline at 24 weeks (P=0.03), a 62% reduction in respiratory function worsening, and an 88% slowing of dyspnea decline. A separate survival analysis suggested 57% improvement in survival, with median extended from 300 to 600 days. These subgroup results were compelling enough for the FDA to clear a pivotal Phase 3 trial.

The Phase 3 PREVAiLS trial enrolled its first participant in April 2026. It will enroll up to 500 patients with early, rapidly progressive ALS at up to 60 centres in 13 countries over 48 weeks. If PREVAiLS succeeds, it would be a major advance — but the patient population defined by "early rapidly progressive ALS" is very different from PLS, which progresses slowly and involves predominantly upper motor neurons. Applicability to PLS would require separate study. The S1R mechanism is not UMN-specific.

PrimeC — Ciprofloxacin/celecoxib combination

Developer: NeuroSense Therapeutics  |  Mechanism: Targets neuroinflammation, iron accumulation, and microRNA dysregulation  |  Stage: Phase 3 PARAGON trial ongoing  |  Evidence level: Emerging

PrimeC is an extended-release tablet combining two existing drugs — the antibiotic ciprofloxacin and the anti-inflammatory celecoxib — in a novel formulation designed to simultaneously target neuroinflammation, iron dysregulation, and microRNA abnormalities in ALS. It is one of the most data-rich pipeline drugs currently in Phase 3.

The Phase 2b PARADIGM trial (NCT05357950) randomized 68 adults 2:1 to PrimeC or placebo for 6 months, then allowed placebo patients to cross over. Results published in JAMA Neurology showed that PrimeC slowed disease progression by 37.4% in the per-protocol adherent group, with a 43% higher survival rate at one year for early continuous treatment. At 18 months, PrimeC participants scored 7.92 ALSFRS-R points higher than placebo crossovers. Real-world data from PARADIGM suggested early treatment extends ALS survival by 14 months. Exploratory biomarker analyses showed lower ferritin and reduced disease-linked microRNAs.

The Phase 3 PARAGON trial, authorized by the FDA in December 2025, will enroll approximately 300 people across the US and EU. As of early 2026, the safety profile continues to be confirmed as favourable. The drug's mechanism — anti-inflammatory and anti-iron accumulation — has theoretical relevance to UMN disease, but there is no PLS-specific data.

CNM-Au8 — Gold nanocrystals (bioenergetic catalyst)

Developer: Clene Nanomedicine  |  Mechanism: Bioenergetic catalyst targeting mitochondrial function and energy metabolism in motor neurons  |  Stage: Accelerated NDA filing planned; HEALEY Platform data  |  Evidence level: Emerging

CNM-Au8 is an oral suspension of gold nanocrystals that acts as a bioenergetic catalyst — meaning it is designed to enhance energy production in metabolically stressed motor neurons rather than targeting a specific genetic or inflammatory pathway. The drug was evaluated in the HEALEY ALS Platform Trial.

FDA-recommended analyses from the HEALEY data showed significant reductions in two biomarkers of nerve injury and inflammation: neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP). Updated analyses from HEALEY also suggest a notable reduction in the risk of death in treated participants. Based on these results, Clene requested a Type C meeting with the FDA in early 2026 and plans to file an accelerated-approval NDA. If approved, CNM-Au8 would be for ALS. Bioenergetic mechanisms are theoretically applicable to upper motor neurons, but there is no PLS-specific evidence.

QRL-201 — ASO targeting stathmin-2 restoration

Developer: Quralis  |  Mechanism: Antisense oligonucleotide designed to restore STMN2 (stathmin-2) expression disrupted by TDP-43 pathology  |  Stage: Phase 1/2 ANQUR trial; Phase 3 planned  |  Evidence level: Emerging

Stathmin-2 is a protein essential for nerve stability and the ability of axons to repair after injury. When TDP-43 protein mislocalizes — as it does in the overwhelming majority of ALS cases — stathmin-2 expression is disrupted, impairing the nerve's ability to maintain and repair itself. QRL-201 is an ASO designed to correct the abnormal splicing of STMN2 mRNA and restore stathmin-2 protein to therapeutic levels.

Interim data from the ANQUR trial (NCT05633459, 69 adults with sporadic ALS) showed that QRL-201 reached its biological target in both the spinal cord and motor cortex. STMN2 levels increased above the estimated therapeutic threshold; splicing of STMN2 mRNA was corrected. The lower-dose group showed a significant reduction in phosphorylated neurofilament heavy chain (pNFH), a marker of nerve damage. Post-hoc analysis showed statistically significant slowing of ALSFRS-R decline after approximately six months. The drug was safe and well tolerated. Quralis is preparing for a pivotal Phase 3 trial.

TDP-43 pathology has been documented in PLS in some studies, making the stathmin-2 pathway of theoretical interest. However, the degree and pattern of TDP-43 mislocalization in PLS is less well characterized than in ALS, and there is no PLS-specific clinical data for QRL-201.

SPG302 (tazbentetol) — Synaptic regenerative compound

Developer: Spinogenix  |  Mechanism: First-in-class oral drug designed to restore glutamatergic synapses between neurons  |  Stage: Phase 2a completed; Expanded Access Program open  |  Evidence level: Emerging

SPG302 (tazbentetol) works by restoring glutamatergic synaptic connections that are lost in the course of neurodegeneration — the physical connections between neurons through which signals are transmitted. The theory is that restoring these connections can maintain motor neuron circuit function even as underlying disease progresses.

A Phase 2a ALS trial (NCT05882695) enrolled 23 participants in a 28-day randomized placebo-controlled period followed by 140 days of active treatment for all. Compared to PRO-ACT historical controls, patients showed an average 76% slower rate of decline through six months. 82% of SPG302-treated patients exhibited a stable or improved rate of decline on ALSFRS-R. EEG recordings showed improvements in ALS-associated brain activity patterns. The drug was well tolerated at 300 mg daily with no treatment-related serious adverse events. SPG302 holds FDA and EMA Orphan Drug Designation for ALS, and an FDA-cleared Expanded Access Program for 200 ALS patients is open.

The synaptic mechanism has relevance to cortical motor circuits — the domain of PLS — and SPG302 is one of the more mechanistically interesting pipeline drugs for upper motor neuron disease. That said, the Phase 2a trial has no control arm comparator for the long-term phase, and PLS-specific data do not exist.

AP-101 — Antibody targeting misfolded SOD1

Developer: AL-S Pharma  |  Mechanism: Human monoclonal antibody that binds and clears misfolded SOD1 protein  |  Stage: Phase 2 completed; Phase 3 planned 2026  |  Evidence level: Emerging

Misfolded SOD1 protein — the toxic clumped form of the protein associated with SOD1-ALS — has been observed not only in patients with SOD1 gene mutations but also in a broader population of ALS patients. AP-101 is a monoclonal antibody designed to identify and clear these misfolded proteins, regardless of whether the patient carries an SOD1 mutation.

The global Phase 2 study enrolled 73 participants and met its primary safety and tolerability endpoints, with adverse events comparable to placebo. Key efficacy findings: early treatment prolonged survival and delayed the need for ventilatory support compared to placebo-then-AP101 participants. Effects were observed in both sporadic ALS (p=0.013) and SOD1 mutation carriers (p=0.036). ALSFRS-R decline was reduced in participants with elevated baseline misfolded SOD1 and in SOD1 mutation carriers. Biomarker changes were favourable. Additional Phase 2 data presented at AD/PD 2026 further demonstrated clinically meaningful disease modification. AL-S Pharma is preparing a confirmatory Phase 3 study. Whether misfolded SOD1 contributes to PLS pathology is unknown; this drug's relevance to PLS is currently theoretical.

IFB-088 (icerguastat) — Integrated stress response activator

Developer: Inflectis Bioscience  |  Mechanism: Activates the integrated stress response, reduces oxidative stress and excitotoxicity  |  Stage: Phase 2 completed (bulbar-onset ALS)  |  Evidence level: Limited

IFB-088 targets two mechanisms linked to motor neuron death: oxidative stress (the buildup of damaging reactive oxygen species) and excitotoxicity (overstimulation of neurons by glutamate). It activates the integrated stress response, a cellular pathway that helps neurons cope with protein misfolding and stress.

The Phase 2 P288ALS trial (NCT05508074) evaluated 51 patients with bulbar-onset ALS alongside standard riluzole therapy, dosed at 25 mg twice daily. The trial met its primary safety endpoint. In the per protocol population, treated patients lost only 0.95 ALSFRS-R points monthly, which represents a meaningfully slower decline rate than historical controls. The bulbar-onset focus means the study population had significant corticobulbar involvement — which overlaps partially with PLS in patients with prominent bulbar symptoms. However, IFB-088 has not been studied in PLS.

VHB937 — Investigational compound in Phase 2

Developer: Undisclosed (UCSD trial)  |  Mechanism: Not publicly disclosed  |  Stage: Phase 2 ASTRALS trial ongoing  |  Evidence level: Limited

VHB937 is an investigational therapy being evaluated in the Phase 2 ASTRALS study (NCT06643481), a randomized double-blind placebo-controlled trial enrolling participants with early-stage ALS (within 2 years of symptom onset, ages 18–100). The trial includes a 40-week core double-blind treatment period followed by an open-label extension. The study started in October 2024 and runs through approximately July 2028 at UCSD and other sites. The mechanism of action has not been disclosed in public materials. Primary measures include adverse events, ALSFRS-R change, and time to permanent ventilation. No PLS-specific information is available.

VTx-002 — Intracisternal first-in-human Phase 1/2

Developer: Undisclosed (UCSD trial)  |  Mechanism: Not publicly disclosed; delivered intracisternally  |  Stage: Phase 1/2 PIONEER-ALS trial, ascending dose  |  Evidence level: Limited

VTx-002 is a first-in-human investigational therapy being evaluated in the PIONEER-ALS study (NCT07287397), an open-label ascending-dose trial administered directly into the cerebrospinal fluid via intracisternal injection. The trial started in December 2025 at UCSD, enrolling ALS patients in two escalating dose cohorts, with a single injection and follow-up of up to 265 weeks. The mechanism and compound class are not yet publicly disclosed. This represents very early-stage clinical development.

Ranolazine — Existing cardiac drug for ALS cramps

Sponsor: UCSF  |  Mechanism: Late sodium channel blocker; reduces aberrant sodium currents that may contribute to motor neuron hyperexcitability and cramps  |  Stage: Phase 2 trial (NCT06527222), results expected mid-2026  |  Evidence level: Limited

Ranolazine is an FDA-approved anti-anginal drug that works by blocking late sodium channel currents. In the context of motor neuron disease, there is a hypothesis that aberrant sodium channel activity contributes to motor neuron hyperexcitability and the cramps that many ALS patients experience. A Phase 2 prospective multicenter double-blind placebo-controlled study is evaluating ranolazine at 500 mg and 1000 mg twice daily versus placebo, targeting muscle cramps, function, and quality of life in ALS patients. Enrollment requires at least four cramps per week. The trial enrolled approximately 72 adults at seven US sites, started in April 2025, and expects completion in May 2026. Cramps are also reported by some PLS patients, and if positive results emerge, this could be relevant — though off-label use in PLS would require specific discussion with a neurologist.

M102 — Chloride channel modulator

Developer: NMD Pharma (University of Sheffield research)  |  Mechanism: Targets the chloride channel cotransporter NKCC1, upregulated in motor neurons in ALS, causing hyperexcitability  |  Stage: Preclinical; IND timeline not confirmed  |  Evidence level: Theoretical

NKCC1 (SLC12A2) is a cotransporter that regulates chloride concentrations inside motor neurons. In ALS, NKCC1 is upregulated, causing abnormal chloride-mediated hyperexcitability — a mechanism related to but distinct from the potassium channel approach of QRL-101. In preclinical MND models, M102 reduced motor neuron degeneration and slowed disease progression. An existing NKCC1 inhibitor (bumetanide, a loop diuretic) is being studied as a comparator. Clinical trials in MND patients are planned, but timeline to IND submission has not been publicly confirmed as of early 2026. The hyperexcitability mechanism is directly relevant to PLS, but M102 remains preclinical.

Ellorarxine — Neuroprotective compound

Developer: Nevrargenics Ltd. (Durham University)  |  Mechanism: Antioxidant, anti-inflammatory; targets neuroprotection, neuroplasticity, and neurorepair  |  Stage: MHRA cleared for human trials; trial not yet started  |  Evidence level: Theoretical

Ellorarxine is a novel compound developed at Durham University and studied by Nevrargenics Ltd. In cell and preclinical models, it shows antioxidant and anti-inflammatory effects at low concentrations, increases expression of key neuroprotective proteins, promotes neurite growth, and improves mitochondrial health. The compound targets what the developers describe as the "3Ns": neuroprotection, neuroplasticity, and neurorepair. Published in the International Journal of Molecular Sciences. The UK MHRA has approved proceeding to human trials, but a trial has not yet started. This remains preclinical with no human safety or efficacy data.

GM1 ganglioside — Neuroprotective glycolipid

Mechanism: Neuroprotective glycolipid that may support motor neuron function and membrane stability  |  Stage: Early-stage human studies  |  Evidence level: Limited

GM1 ganglioside (monosialotetrahexosylganglioside) is a glycolipid naturally present in neuronal cell membranes. It has been studied over decades as a potential neuroprotective agent in various neurological conditions. A 2024–2025 study reported improvements in motor function in ALS patients treated with GM1, but the evidence base is early-stage and lacks the controlled trial rigour of the other compounds on this page. Larger controlled trials are needed. No PLS-specific data exist.

IPL344 — Neuroinflammation target

Developer: Immunity Pharma  |  Mechanism: Neuroinflammatory pathway targeting; details not publicly disclosed  |  Stage: Early; clinical development details not public  |  Evidence level: Theoretical

Immunity Pharma presented new data supporting the efficacy of IPL344 in ALS in April 2025. The mechanism of action targets neuroinflammation, a pathway increasingly recognized as important in MND, but detailed information about the mechanism and clinical development stage has not been publicly released. This remains a very early entry in the pipeline with limited peer-reviewed evidence available.

TRE-515 — Expanded access compound

Stage: Expanded access for 6 patients; early-stage  |  Evidence level: Theoretical

TRE-515 was announced in April 2026 via an ALS partnership providing expanded access to six patients. This level of access — six patients, compassionate use — indicates very early clinical development. No mechanism of action or clinical data are publicly available from indexed sources. It is listed here for completeness; there is currently no basis for evaluating this compound's relevance to PLS.

Ravulizumab — Complement C5 inhibitor

Developer: AstraZeneca (Ultomiris)  |  Mechanism: Inhibits complement C5, blocking the terminal complement cascade implicated in neuroinflammation and neuromuscular junction damage  |  Stage: Phase 3 trial completed; not currently recruiting  |  Evidence level: Limited

Ravulizumab (Ultomiris) is an approved drug for other indications that was evaluated in a Phase 3, double-blind, randomized, placebo-controlled multicenter ALS trial (NCT04248465). The trial required ALS diagnosis per El Escorial criteria, onset within 36 months, and documented meningococcal vaccination. The trial has completed and is not currently recruiting. Full results have not been prominently published as of early 2026. Complement pathway involvement in motor neuron disease is an active area of research; if results emerge, they may be informative for the broader MND field including PLS.

What this means for PLS patients

Looking across this pipeline, a few patterns are worth noting for people with PLS specifically:

• The drugs with the most plausible UMN-relevant mechanisms — QRL-101 (motor neuron hyperexcitability), QRL-201 (TDP-43/STMN2 pathway), SPG302 (cortical synaptic restoration), M102 (chloride channel hyperexcitability) — are all still in early trials or preclinical stages. They merit watching.
• No currently active trial enrolls PLS patients explicitly in this drug pipeline. The closest option remains the PLS Natural History Study and the trials listed on the clinical trials page.
• If you are interested in trial participation, discussing eligibility with your neurologist — including whether any ALS trials might accept participants with UMN-predominant phenotypes — is the most productive path. Some ALS platform trials have accepted phenotypically restricted cohorts.