All seven children in the lowest dose cohort of Abbisko’s Phase 2 lavengratinib study grew an average of 2.4 centimeters per year faster than their baseline rate after 27 weeks, and every single participant met the trial’s responder threshold, which required at least a 25% improvement in annualized height velocity. That 100% responder rate, from a cohort where children received just 0.064 mg/kg once daily, is the number that makes this readout worth watching: it came from the floor of the dose range, with higher cohorts still ongoing.
The comparison point for any achondroplasia growth therapy is vosoritide (Voxzogo), which in its pivotal Phase 3 study produced roughly 1.57 centimeters of additional annual height gain over placebo. Lavengratinib’s 2.4 cm/year mean improvement from baseline in an open-label, single-arm design cannot be read as a head-to-head figure, but the magnitude is large enough to keep regulators and competitors paying attention as the dose escalation continues.
The safety profile so far is the other consequential finding. Earlier oncology data confirmed lavengratinib’s tolerability in adults, but FGFR pathway inhibitors carry well-documented risks tied to FGFR1 activity, including hyperphosphatemia and corneal toxicity. In the pediatric ACH cohort, none of those signals appeared across any of the first three dose levels. No serious adverse events and no treatment discontinuations were reported. That clean run through the lowest cohort, without FGFR1-associated toxicity, is the mechanistic argument for why a selective FGFR2/3 inhibitor could hold an advantage in a condition where children will need long-term dosing. Abbisko also built a mini-tablet formulation with tablets under 3 mm in diameter, about a third the size of a conventional tablet, specifically to make daily oral dosing workable in young children.
Lavengratinib holds both Rare Pediatric Disease and Orphan Drug Designations from the FDA for achondroplasia, which matters for the regulatory path ahead. The six-month efficacy and safety dataset, expected before year-end 2026, will be the first look at whether the signal holds as the dose escalation reaches its higher cohorts.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
