Fasudil

Fasudil is a Rho-associated protein kinase (ROCK) inhibitor approved in Japan since 1995 as intravenous Eril for cerebral vasospasm after subarachnoid hemorrhage, but never approved in the US or EU. Woolsey Pharmaceuticals is repurposing it as an oral formulation (WP-0512, branded Bravyl) for amyotrophic lateral sclerosis (ALS) in the Phase 2a REAL trial (NCT05218668) [1]. Parallel Phase 2 programs from academic sponsors are testing the same molecule in early Alzheimer's (FEAD, NCT06362707) [2] and Parkinson's (NCT05931575) [3], plus small oncology combinations. The most important prior efficacy data is the European ROCK-ALS Phase 2 RCT (NCT03792490), which met its primary safety and tolerability endpoints and reported a positive secondary electrophysiology signal (MUNIX slope and reduced spread of motor unit loss across body regions) in the Lancet Neurology 2024 primary publication [6], with a follow-up MUNIX post-hoc paper in 2026 [5]. The commercial thesis rests on whether that secondary electrophysiology signal converts to a real functional benefit in a properly powered Phase 3, a step that has failed repeatedly for other neuroprotective agents over the past two decades.

Not a novel compound. Intravenous fasudil has been marketed by Asahi Kasei in Japan since 1995 for preventing delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage, where it is still the standard of care and remains an active comparator in the SAVIOR trial against clazosentan [4]. Outside Japan it has no regulatory approval. Woolsey holds no FDA breakthrough, fast track, orphan, or RMAT designations disclosed publicly for the ALS program. The REAL trial is a Phase 2a safety and tolerability study (n=40, ACTIVE_NOT_RECRUITING as of the most recent registry pull; estimated primary readout H2 2026 to H1 2027 based on 12 to 18 month safety follow-up after enrollment completion) [1]. The Parkinson's Phase 2 at TU Munich completed enrollment at n=81 with primary readout on safety and self-reported serious adverse events [3]. The FEAD Alzheimer's trial (n=200, cognition endpoint) is still recruiting [2]. The European ROCK-ALS trial (NCT03792490), a 131-patient randomized placebo-controlled Phase 2 of intravenous fasudil run by academic investigators, reported its primary results in Lancet Neurology 2024: primary safety and tolerability endpoints were met, and prespecified secondary electrophysiology endpoints (MUNIX decline slope and number of newly affected muscles at day 90) favored fasudil over placebo [6]. A separate 2026 MUNIX post-hoc analysis extended that signal to suggest an effect on disease spreading between body regions [5]. Timelines for Woolsey's next regulatory step have not been publicly disclosed, and Woolsey's disclosed financing status (last raise, runway, industry partnership) is not publicly available as of this writing, which is material for a small private sponsor facing a capital-intensive Phase 3.

ROCK is an enzyme that controls the cell's internal scaffolding, the actin cytoskeleton, which determines how cells hold their shape, move, and extend processes. In neurons, hyperactive ROCK causes axons (the long wires that carry signals) to collapse and prevents them from regrowing after injury. In ALS, ROCK activity is elevated in motor neurons and surrounding glial cells, and blocking it has extended survival in SOD1 (superoxide dismutase 1, a gene mutated in roughly 2% of ALS cases) mutant mouse models of the disease. Fasudil crosses the blood-brain barrier and inhibits both ROCK1 and ROCK2, reducing neuroinflammation, protecting axonal transport, and dampening reactive astrocyte responses that damage neighboring neurons. The genetic case for ROCK in ALS is indirect. There is no ROCK mutation that causes ALS. The rationale rests on preclinical rescue in SOD1 mice plus mechanistic overlap with pathways broken in sporadic disease. Open Targets ranks ROCK1 evidence highest for glaucoma and ocular hypertension, not ALS, where it registers only as generic 'neurodegenerative disease' association. That is a real weakness in the target validation story compared to, for example, SOD1 or C9orf72 (a hexanucleotide repeat expansion gene, the most common genetic cause of familial ALS) antisense approaches where genetics is airtight. No ROCK inhibitor has yet demonstrated a functional clinical benefit in any neurological indication anywhere in the world, which is the honest de-risking backdrop for this program.

REAL (NCT05218668) is a Phase 2a, single-arm, open-label safety and tolerability study of oral WP-0512 in 40 ALS patients, with the primary endpoint being incidence of adverse events and serious adverse events [1]. There is no placebo comparator, no functional primary endpoint, and no biomarker enrichment. This is a bridge study, powered to answer whether an oral dose is tolerated well enough to justify a larger controlled trial, not whether the drug slows ALS. ALSFRS-R (ALS Functional Rating Scale, Revised: a 48-point questionnaire tracking daily function like speaking, swallowing, and walking) slope and survival are almost certainly secondary or exploratory endpoints, but 40 open-label patients cannot separate real drug effect from natural history heterogeneity. The parallel European ROCK-ALS trial (NCT03792490, a 131-patient randomized double-blind placebo-controlled study of IV fasudil) already read out its primary analysis in Lancet Neurology 2024 [6]. Primary safety and tolerability endpoints were met (fasudil was well tolerated with no unexpected safety signals). Secondary electrophysiology endpoints favored fasudil over placebo, specifically MUNIX (Motor Unit Number Index, an electrophysiological test that estimates the number of surviving motor neurons, the cells that die in ALS, by measuring compound muscle electrical responses) slope of decline and the number of newly affected muscle regions at day 90. The 2026 Wolff et al. MUNIX post-hoc paper extended that signal by showing an apparent effect on the spread of motor unit loss between body regions [5]. Both the primary secondary readout and the post-hoc are electrophysiological, not functional or survival, endpoints. A ROCK-ALS Phase 3 with a functional primary endpoint would be the next real de-risking event.

Our model estimates a 12% chance this drug is eventually approved. It starts from the historical base rate for Phase 2 drugs in this area (about 24%), then adjusts using ten facts about the trial and sponsor. What moves the number most: it is helped by a non-randomized design and its light or open-label blinding; it is held back by the sponsor's thin or weak approval record and weak or limited earlier-phase results. The other facts land near average for this stage, so they leave the estimate roughly where the base rate put it.

Efficacy risk is the dominant threat. ROCK inhibition is a broad, upstream cytoskeletal intervention with no genetic anchor in ALS, and the field is littered with plausible-mechanism failures (ceftriaxone, dexpramipexole, arimoclomol). ROCK-ALS did produce a positive secondary electrophysiology readout but no functional or survival benefit has yet been demonstrated, and a 40-patient open-label safety trial like REAL cannot close that gap. Safety risk is real but bounded. Fasudil is a vasodilator by mechanism, and dose-limiting hypotension has been observed with IV use in cerebral vasospasm patients. The oral formulation lowers peak exposure but adds bioavailability variability. Execution risk is high: Woolsey is a small private company, the drug has been 'about to be repurposed' for neurology since the early 2010s without a Phase 3 launching, and financing a pivotal ALS trial (typically 300+ patients, 12+ months) is nontrivial. Woolsey has not publicly disclosed a recent financing raise, industry partnership, or runway, which is a material information gap for investors. Commercial risk: even if approved, fasudil is a decades-old molecule with generic exposure in Japan. Composition-of-matter patent life is exhausted; Woolsey's IP position rests on formulation, dose, and method-of-use claims, which are weaker fences against generic entry once a market is established. Reference-class note on edaravone: Mitsubishi Tanabe voluntarily withdrew the IV form (Radicava) from the US market in October 2024 for commercial reasons explicitly unrelated to safety or efficacy; the oral suspension (Radicava ORS, approved 2022) remains on the US market.

Watch, do not chase. The ROCK-ALS primary Lancet Neurology 2024 publication [6] already exists and already showed a positive secondary electrophysiology signal on top of a met safety primary, so the earlier framing that this data is still awaited is wrong. What is still missing is a functional or survival readout in a properly powered Phase 3. Woolsey's REAL trial itself will not answer the efficacy question either, so treat its readout as a gating event for Phase 2b design, not for the mechanism. Check back when: (1) a ROCK-ALS Phase 3 (or comparable functional-endpoint Phase 2b) is protocol-registered with ALSFRS-R slope or survival as primary, (2) Woolsey announces a Phase 2b or 3 protocol with a functional primary endpoint and discloses financing or a partner to run it, (3) the FEAD Alzheimer's trial reads cognition data (2027 at earliest) [2], or (4) any ROCK inhibitor anywhere shows a functional clinical benefit in a neurological indication, which would materially de-risk the target class. Until then, this is a mechanism with a real but non-functional Phase 2 signal, attached to a repurposed generic, run by a small sponsor with undisclosed runway, in the hardest indication in neurology.