Pediatric clinical trials update: May 2026

May brought a steady stream of clinical trial developments with potential implications for pediatric care, spanning infectious diseases, neurology, endocrinology, gastroenterology, and rare diseases. From new data on antiviral prevention strategies and emerging therapies for Tourette syndrome to advances in diabetes management and treatments for pediatric cardiomyopathy, investigators reported findings that may help shape future clinical practice and regulatory decisions.

This monthly clinical trial recap highlights key studies, trial results, and pipeline developments reported during May 2026 that pediatricians should have on their radar.

1. Berdazimer gel improves clearance rates in phase 3 molluscum contagiosum trial

Topline results from the phase 3 B-SIMPLE4 trial demonstrated that berdazimer 10.3% topical gel improved complete lesion clearance in patients aged 6 months and older with molluscum contagiosum, meeting its primary endpoint at 12 weeks. Among 891 participants, 32.4% of patients treated with berdazimer achieved complete resolution of all lesions compared with 19.7% of those receiving vehicle.

Pooled analyses from multiple randomized studies showed similar findings, with complete clearance rates of approximately 30.0% vs 19.8%, respectively. Benefits were observed across demographic and clinical subgroups, including children with atopic dermatitis, and patient-reported outcomes indicated greater perceived improvement with active treatment. Berdazimer was generally well tolerated, with adverse events primarily limited to mild application-site reactions, supporting its potential role as a noninvasive treatment option for pediatric patients with molluscum contagiosum.

2. Crinecerfont shows durable hormone control, lower steroid doses in pediatric CAH at 2 years

Two-year results from the phase 3 CAHtalyst Pediatric open-label extension demonstrated that crinecerfont (Crenessity) provided durable hormonal control while allowing reductions in glucocorticoid exposure among children and adolescents with classic congenital adrenal hyperplasia (CAH). Among 86 patients aged 4 to 17 years, treatment was associated with sustained decreases in adrenocorticotropic hormone and 17-hydroxyprogesterone levels through 24 months, alongside a mean reduction of 3.2 mg/m²/day in glucocorticoid dosing.

Investigators also reported improvements in cardiometabolic outcomes, with 60% of overweight or obese participants achieving clinically meaningful reductions in BMI standard deviation scores and 61% of those with baseline insulin resistance no longer meeting criteria for insulin resistance after 2 years. Additional benefits included improvements in acne severity and androgen-related measures, while no new safety signals emerged and study retention exceeded 80%. The findings provide the longest pediatric follow-up to date for crinecerfont and support its role as a steroid-sparing treatment option for children with classic CAH.

3. Ersodetug misses primary endpoint in phase 3 sunRIZE trial for congenital hyperinsulinism

Expanded analyses from the phase 3 sunRIZE trial suggest that ersodetug, an investigational allosteric insulin receptor antagonist, may improve glycemic control in patients with congenital hyperinsulinism despite the study not meeting its primary endpoint. The randomized, placebo-controlled trial enrolled 63 patients aged 3 months to 45 years and evaluated ersodetug as an add-on to standard therapy.

While the primary self-monitored blood glucose–based endpoint was not achieved, continuous glucose monitoring analyses demonstrated reductions in hypoglycemia, increased time spent in normoglycemia, and higher average glucose levels compared with placebo. Investigators also reported encouraging findings from the ongoing open-label extension, with nearly all study completers electing to continue treatment and preliminary data suggesting sustained glycemic benefits alongside reductions in background therapies such as diazoxide, somatostatin analogs, and tube feeding support. Although the regulatory pathway remains uncertain, the results highlight the potential of ersodetug as a novel treatment approach for congenital hyperinsulinism, a rare disorder with limited therapeutic options.

4. TransCon CNP shows sustained growth gains in children 5 years and older with achondroplasia

Two-year results from the pivotal ApproaCH trial showed that once-weekly TransCon CNP (navepegritide) produced sustained improvements in growth among children aged 5 years and older with achondroplasia. In the phase 3 study, children treated with TransCon CNP achieved significantly greater annualized growth velocity at 52 weeks compared with placebo, with gains maintained through 104 weeks during the open-label extension. Improvements were also observed in achondroplasia-specific and CDC-based height z-scores, indicating continued progress in linear growth over time.

The therapy demonstrated a favorable safety profile through 2 years, with mostly mild or moderate adverse events, low rates of mild injection-site reactions, no symptomatic hypotension, and no evidence of accelerated bone age. The findings further support the long-term efficacy and tolerability of TransCon CNP, which received FDA approval in February 2026 for pediatric patients aged 2 years and older with achondroplasia and open epiphyses.

5. ABS-1230 enters phase 1b/2 testing in KCNT1-related epilepsy amid FDA rare disease planning

Actio Biosciences announced the initiation of the phase 1b/2 KYRON trial evaluating ABS-1230, an investigational small-molecule KCNT1 inhibitor, in children and young adults with genetically confirmed KCNT1-related epilepsy. The study will enroll patients aged 1 month to 21 years and includes an open-label treatment period, a randomized placebo-controlled phase, and an optional open-label extension, with assessments focused on safety, pharmacokinetics, seizure activity, and neurodevelopmental outcomes.

Although no efficacy data are yet available, the program represents an important step toward a genotype-directed treatment approach for a rare developmental and epileptic encephalopathy characterized by severe, often treatment-resistant seizures and significant neurodevelopmental impairment. Early phase 1a data in healthy volunteers showed favorable tolerability with no serious adverse events reported, and the program has been accepted into the FDA’s Rare Disease Evidence Principles framework, which is designed to support drug development in ultrarare genetic disorders. The trial marks an early-stage effort to address a significant unmet need in pediatric epilepsy, where disease-specific treatment options remain limited.

6. AK-OTOF shows early hearing restoration potential in children with OTOF-mediated hearing loss

Preliminary findings from the phase 1/2 AK-OTOF-101 trial suggest that AK-OTOF, an investigational gene therapy for OTOF-mediated sensorineural hearing loss, may restore functional hearing in children with inherited deafness. Data presented from 18 participants who received bilateral treatment showed that 80% of those receiving the higher dose achieved hearing improvement to at least a moderate hearing loss level, with auditory responses observed as early as 30 days after administration.

According to investigators, improvements in auditory brainstem responses and behavioral hearing measures have remained stable or continued to improve over follow-up, with some participants now monitored for up to 2 years. The therapy was generally well tolerated, with no serious adverse events related to treatment, delivery, or the administration procedure reported. Although the trial remains ongoing, the findings highlight the potential of gene therapy to address the underlying genetic cause of hearing loss and may signal a future shift toward precision medicine approaches for children with inherited forms of deafness.

7. RVL-001 enters early n-of-1 studies for Rett syndrome and Pitt-Hopkins syndrome

Unravel Biosciences has initiated 2 early proof-of-concept studies evaluating RVL-001, a proprietary formulation of the histone deacetylase inhibitor vorinostat, in patients with Rett syndrome and Pitt-Hopkins syndrome. The placebo-controlled n-of-1 trials are expected to enroll 15 patients with Rett syndrome and 5 with Pitt-Hopkins syndrome and will assess the potential of epigenetic modulation as a treatment strategy for these rare neurodevelopmental disorders. The studies represent an early-stage effort to address significant unmet needs, particularly in Pitt-Hopkins syndrome, which currently has no approved disease-directed therapies.

Although no efficacy data are available, the program is based on the hypothesis that targeting transcriptional dysregulation may improve disease manifestations associated with MECP2 and TCF4 abnormalities. Investigators anticipate study completion in early 2027, with results expected to provide initial insights into the safety and potential clinical activity of RVL-001 in these ultra-rare pediatric populations.

8. Phase 2b UK trial to test Lactin-V for preterm birth prevention

Researchers in the United Kingdom have launched FLIP-2, a phase 2b randomized, placebo-controlled trial evaluating whether Lactin-V, a vaginal live biotherapeutic containing Lactobacillus crispatus CTV-05, can reduce the risk of preterm birth in pregnant patients at high risk for early delivery. The study will enroll 360 participants across 4 maternity centers and builds on findings from the earlier FLIP-1 pilot study, which demonstrated that Lactin-V was generally well tolerated and acceptable during pregnancy. The therapy is designed to restore a vaginal microbiome dominated by L crispatus, a bacterial species associated with lower levels of genital tract inflammation and potentially improved pregnancy outcomes.

Although the biologic rationale is promising, it remains unclear whether microbiome modification can meaningfully reduce preterm birth rates. The trial represents an important effort to address a significant unmet need in obstetric care, particularly as treatment options for preterm birth prevention remain limited following the withdrawal of hydroxyprogesterone caproate from the US market.

9. RGX-202 demonstrates positive phase 3 results for Duchenne muscular dystrophy

Topline results from the pivotal phase 3 portion of the AFFINITY DUCHENNE study showed that the investigational gene therapy RGX-202 met its primary biomarker endpoint in ambulatory boys with Duchenne muscular dystrophy (DMD), with 93% of treated participants achieving greater than 10% microdystrophin expression at 12 weeks. Investigators reported a mean microdystrophin expression level of 71.1% and observed a correlation between early microdystrophin expression and functional outcomes at 1 year.

Preliminary analyses of a small subset of participants suggested improvements in motor function measures, including the North Star Ambulatory Assessment, compared with external controls. RGX-202 was generally well tolerated, although 2 serious adverse events—subacute myocarditis and asymptomatic liver injury—were reported and resolved without long-term complications. While the findings support continued development of RGX-202 and add to growing evidence surrounding microdystrophin-based gene therapies in DMD, longer-term follow-up and confirmatory clinical data will be needed to establish the durability of benefit and inform future regulatory decisions.

10. Preclinical DMD gene therapy GB703 debuts as GEMMABio advances SMA program

Gemma Biotherapeutics presented new preclinical data on 2 investigational gene therapy programs targeting neuromuscular disorders: GB703 for Duchenne muscular dystrophy (DMD) and GB221 for spinal muscular atrophy type 1 (SMA1). Preclinical findings for GB703 demonstrated muscle-targeted delivery and expression of a hybrid micro-utro/dystrophin transgene, with evidence of improved muscle function markers and restoration of key structural proteins in animal models of DMD. The company said the data support advancement toward investigational new drug–enabling studies.

For SMA1, preclinical data for GB221 showed prolonged survival, improved motor function, and favorable biodistribution in animal models, while early findings suggested a strategy designed to reduce dorsal root ganglia toxicity, a known challenge in systemic gene therapy. GB221 is currently being evaluated in the phase 1/2 CHARISMA trial in infants with SMA1. Although both programs remain in the early stages of development, the results highlight ongoing efforts to improve the safety, targeting, and effectiveness of next-generation gene therapies for pediatric neuromuscular diseases.

11. BMN 401 raises plasma PPi but misses skeletal end point in pediatric ENPP1 deficiency

Results from the pivotal phase 3 ENERGY 3 trial showed that BMN 401, an investigational enzyme replacement therapy for ENPP1 deficiency, successfully increased plasma inorganic pyrophosphate (PPi) levels but did not demonstrate a corresponding improvement in skeletal disease over 52 weeks. In the study of 27 children aged 1 to 12 years, BMN 401 met 1 of its 2 co-primary endpoints by significantly improving the biochemical marker PPi compared with conventional therapy.

However, the therapy failed to show benefit on the Radiographic Global Impression of Change score, a measure of clinically meaningful improvement in rickets severity, and no favorable trends were observed across secondary endpoints evaluating rickets severity or growth. BMN 401 was generally well tolerated, with no new safety concerns reported. The findings highlight the challenges of translating biomarker improvements into measurable clinical outcomes in rare pediatric disorders and raise important questions about the relationship between biochemical correction and skeletal benefit in children with ENPP1 deficiency.

12. ECUR-506 shows early response in neonatal-onset OTC deficiency trial

Preliminary data from the ongoing OTC-HOPE trial suggest that ECUR-506, an investigational in vivo gene insertion therapy, may reduce metabolic crises in infants with severe neonatal-onset ornithine transcarbamylase (OTC) deficiency. In the first completed low-dose cohort, 3 treated infants experienced a 57% reduction in annualized hyperammonemic events and a 65% reduction in hyperammonemic crises compared with pretreatment rates. Two participants remained free of both event types after treatment, while one infant reportedly discontinued ammonia-scavenging therapy, liberalized dietary protein intake, and remained free of hyperammonemic events through 18 months of follow-up.

Across 7 treated participants spanning multiple dose cohorts, investigators reported no unexpected treatment-related safety concerns, infusion reactions, or thrombotic microangiopathy. Although the findings are based on a small, uncontrolled cohort, they provide early evidence that targeted gene insertion may offer a novel approach to reducing disease burden in neonatal-onset OTC deficiency, a rare and life-threatening urea cycle disorder with limited treatment options beyond intensive medical management and liver transplantation.

13. Zovegalisib shows early promise in PIK3CA-driven vascular anomalies

Initial phase 2 data from the ReInspire trial suggest that zovegalisib, an investigational PI3Kα mutant-selective inhibitor, may provide meaningful clinical benefit for patients with PIK3CA-driven vascular anomalies, including PIK3CA-related overgrowth spectrum, lymphatic malformations, and venous malformations. Among 20 response-evaluable adolescents and adults aged 12 years and older, 60% achieved at least a 20% reduction in lesion volume at 12 weeks, with 95% experiencing some degree of lesion shrinkage.

Investigators also reported improvements in patient- and clinician-reported outcomes, including pain and overall disease status. The treatment demonstrated a favorable safety profile at the 100-mg and 300-mg twice-daily doses, with few serious treatment-related adverse events and no reported grade 3 hyperglycemia or diarrhea in these cohorts. Although enrollment is ongoing and pediatric expansion cohorts are still being evaluated, the early findings support continued development of zovegalisib as a potential targeted therapy for patients with PIK3CA-driven vascular anomalies, a group of rare disorders with limited long-term treatment options.

14. Phase 3 trial shows vosoritide improves growth in children with hypochondroplasia

Positive phase 3 results from the CANOPY-HCH-3 trial demonstrated that vosoritide (VOXZOGO) significantly improved growth outcomes in children with hypochondroplasia, a rare skeletal dysplasia for which no approved therapies currently exist. In the global randomized, placebo-controlled study of 80 children aged 3 to 17 years, treatment with vosoritide resulted in a statistically significant increase in annualized growth velocity compared with placebo, with a least squares mean difference of 2.33 cm per year after 52 weeks.

Investigators also reported significant improvements in standing height, height Z-scores, and arm span, a secondary endpoint that may have implications for daily function and independence. The safety profile was consistent with previous experience in achondroplasia, with no new safety signals identified. Based on these findings, BioMarin plans to submit a supplemental New Drug Application to the FDA in the third quarter of 2026, positioning vosoritide as a potential first approved therapy for children with hypochondroplasia.

15. Ecopipam phase 3 data demonstrates reduced Tourette relapse risk in youth

Results from a phase 3 randomized-withdrawal trial suggest that continued treatment with ecopipam, an investigational dopamine D1 receptor antagonist, may help maintain tic control and reduce relapse risk in children and adolescents with Tourette syndrome. After an initial 12-week open-label treatment period involving 216 participants, including 167 pediatric patients, responders were randomized to continue ecopipam or switch to placebo. Investigators reported that patients who remained on ecopipam experienced a 50% lower risk of relapse than those transitioned to placebo.

The therapy was generally well tolerated, with adverse events described as mild to moderate and consistent with previous studies. Unlike currently approved Tourette syndrome medications, which primarily target dopamine D2 receptors, ecopipam acts through a distinct D1 receptor mechanism and may offer an alternative approach to tic management. The findings, published in JAMA Neurology, are expected to support a planned FDA submission and position ecopipam as a potential new treatment option for pediatric patients with Tourette syndrome.