The U.S. Food and Drug Administration has approved Cablivi (caplacizumab-yhdp) for use in pediatric patients aged 12 years and older with acquired thrombotic thrombocytopenic purpura (aTTP), in combination with plasma exchange and immunosuppressive therapy. The approval is based on retrospective pediatric data demonstrating high remission rates, with bleeding identified as the primary safety concern.
Written By: Pharmacally Medical News Desk
On January 5, 2026, the FDA expanded the label for Cablivi to include pediatric patients aged 12 years and older with aTTP. This marks the first FDA approval of a therapy specifically for pediatric aTTP and provides clinicians with a targeted option to reduce microvascular thrombosis while underlying autoimmunity is addressed through standard therapies.
The pediatric approval was supported by a retrospective chart review of 30 pediatric patients aged 2 to 18 years. In this dataset, 80% of patients achieved clinical remission, defined as normalization of platelet count and lactate dehydrogenase (LDH) levels below 1.5 times the upper limit of normal for at least 30 consecutive days.
How Cablivi works
Cablivi works by blocking von Willebrand factor (vWF), a key protein responsible for abnormal platelet adhesion in acquired TTP. By preventing this harmful platelet clumping, Cablivi helps stop the formation of microvascular blood clots. This allows platelet counts to recover more rapidly while plasma exchange and immunosuppressive therapy treat the underlying immune-mediated cause of the disease.
Clinical data and context
Because randomized pediatric trials were not feasible due to the rarity and acute nature of pediatric aTTP, the FDA evaluated pediatric retrospective data alongside established adult clinical trial evidence.
Adult pivotal data
Adult efficacy was demonstrated in the Phase 3 HERCULES trial, NCT02553317 where Cablivi significantly reduced time to platelet normalization, with patients 1.55 times more likely to achieve platelet recovery at any given time point (p=0.01). The trial also showed a 74% reduction in the composite endpoint of aTTP-related death, recurrence, or major thromboembolic events compared with placebo. These findings established robust clinical benefit and supported extrapolation of efficacy to pediatric patients.
Pediatric evidence
Although Cablivi was initially approved only for adults with aTTP, it had been prescribed off-label in pediatric patients in urgent, life-threatening settings based on adult efficacy data and its age-independent mechanism of action. Outcomes from this real-world use formed the basis of the pediatric evidence supporting label expansion.
In the retrospective analysis, 80% of pediatric patients achieved sustained clinical remission. The safety profile observed, including bleeding risk, was consistent with adult experience. The FDA evaluated these findings together with adult randomized trial data, pharmacokinetic modeling, and mechanistic evidence, concluding that the totality of evidence supported approval for pediatric patients aged 12 years and older.
Safety profile
The safety profile in pediatric patients was consistent with that observed in adults, with bleeding identified as the primary risk. Common adverse reactions included epistaxis, headache, and gingival bleeding.
Regulatory considerations
Cablivi has received Orphan Drug designation for aTTP. The updated U.S. label states that safety and effectiveness have not been established in children under 12 years of age and includes pediatric pharmacology and safety information derived from modeling, retrospective data, and adult clinical trials. Clinicians are advised to consult the full prescribing information for detailed guidance.
About acquired TTP
Acquired TTP is a rare autoimmune disorder caused by severe deficiency of ADAMTS13 due to autoantibodies. The condition leads to accumulation of ultra large vWF multimers, platelet aggregation in small blood vessels, microangiopathic hemolytic anemia, thrombocytopenia, and organ ischemia. Pediatric aTTP is extremely rare, with an estimated incidence of approximately one case per 10 million children annually and can be rapidly fatal without prompt plasma exchange and immunosuppressive treatment.
Reference
FDA approves therapy for rare blood disorder in pediatric patients 12 years and older, 05 January 2026, https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-therapy-rare-blood-disorder-pediatric-patients-12-years-and-older
CABLIVI (caplacizumab-yhdp), Highlights of prescribing information, https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/761112s018lbl.pdf
Marie Scully et al, Caplacizumab Treatment for Acquired Thrombotic Thrombocytopenic Purpura, N Engl J Med 2019;380:335-346, DOI: 10.1056/NEJMoa1806311
Bergstrand M et al, Caplacizumab Model-Based Dosing Recommendations in Pediatric Patients with Acquired Thrombotic Thrombocytopenic Purpura. J Clin Pharmacol. 2022 Mar;62(3):409-421. Epub 2021 Nov 29. PMID: 34699078; PMCID: PMC9255589. https://doi.org/10.1002/jcph.1991
Phase III Trial with Caplacizumab in Patients with Acquired Thrombotic Thrombocytopenic Purpura (HERCULES), ClinicalTrials.gov ID NCT02553317, https://clinicaltrials.gov/study/NCT02553317