ABS-1230 entered phase 1b/2 testing for KCNT1-related epilepsy as Actio also joined the FDA Rare Disease Evidence Principles process.
Actio Biosciences has opened a phase 1b/2 trial of ABS-1230, an investigational KCNT1 inhibitor, for children and young adults with KCNT1-related epilepsy, a rare developmental and epileptic encephalopathy marked by early-onset, often drug-resistant seizures and substantial neurodevelopmental impairment. The company also said the program has been accepted into the FDA’s Rare Disease Evidence Principles (RDEP) process, a newer framework intended to guide development in ultrarare, genetically defined disorders.1
The announcement is notable because treatment options for KCNT1-related epilepsy remain limited and largely supportive. “For families in this community, including mine, the focus each day is simple and urgent: keeping our children alive,” Justin West, MD, cofounder and president of the KCNT1 Epilepsy Foundation, said in the company’s release. For clinicians, the update signals both a first patient study in the target population and potentially earlier regulatory alignment for a precision therapy aimed at the underlying channelopathy.
According to the company, the KYRON study will enroll patients aged 1 month through 21 years with genetically confirmed KCNT1-related epilepsy. The trial includes 3 parts: (1) a 12-week open-label single-arm treatment period, (2) a 12-week, randomized, double-blind, placebo-controlled portion in additional participants, and (3) an optional open-label extension. ABS-1230 may be given orally or through a feeding tube, which is clinically relevant in a population in which swallowing difficulties and medical complexity are common.
Actio said initial enrollment will begin with older children and young adults, with expansion into younger children and infants dependent on safety, tolerability, and dose confirmation in each age cohort. The prespecified study assessments include safety, tolerability, pharmacokinetics, seizure activity, and neurodevelopmental outcomes. No efficacy results from the patient trial are available.
The only clinical safety data disclosed in the release come from a phase 1a healthy volunteer study, in which “all doses of ABS-1230, including multiple doses of 20 mg, were well tolerated with no serious adverse events reported,” according to the company. Those findings are necessarily preliminary and may not predict tolerability in infants and children with severe epilepsy, who often receive multiple antiseizure medications and have significant comorbidity.
KCNT1-related epilepsy is associated with gain-of-function variants in the sodium-activated potassium channel subunit KCNT1 and can present as epilepsy of infancy with migrating focal seizures or other severe developmental and epileptic encephalopathy phenotypes.2,3 Published case series suggest high seizure burden, profound developmental disability, and elevated mortality, while responses to currently available antiseizure therapies have been inconsistent.2,3 Quinidine, a partial KCNT1 channel blocker, has been used off-label in some patients, but clinical benefit has varied, and cardiac monitoring requirements have limited broader use.2
ABS-1230 is described by the company as a potent, selective, orally available small-molecule KCNT1 inhibitor designed to address the functional consequence of pathogenic variants.1 That mechanism fits a broader trend in rare epilepsies toward genotype-directed treatment, although translation from ion-channel pharmacology to durable clinical benefit has been challenging across developmental epileptic encephalopathies.
The RDEP designation may prove important if early data are encouraging. The FDA introduced the framework in 2025 to support development programs in very small, genetically defined rare diseases in which traditional large trials may be impractical.4 As summarized by Actio, the process allows early FDA discussion of what may constitute substantial evidence of effectiveness and may, in some circumstances, support reliance on a single adequate and well-controlled study with confirmatory evidence. Still, entry into the program is not an approval decision, and it does not lower statutory standards for safety and effectiveness.4
Several questions remain. The company has not disclosed planned enrollment numbers, primary efficacy end points, or statistical assumptions. It also remains unclear how seizure outcomes will be measured across the trial’s broad age range and phenotypic variability, or how neurodevelopmental assessments will be standardized in a small rare-disease cohort. Longer-term safety, including potential off-target effects and interactions with background antiseizure therapy, will require follow-up.
For now, the KYRON trial represents an early but clinically relevant step in a field with few disease-specific options. Whether selective KCNT1 inhibition can translate into meaningful seizure reduction or developmental benefit will depend on data that have not been reported.
