Endo 2022 – Voxzogo’s prospects shrink

The prospects for Biomarin’s achondroplasia therapy Voxzogo in very young children had already looked murky after a vague update earlier this year. Now the company has given – some – further details, and things are still far from clear. The results, presented in a poster at the Endo meeting, came from a phase 2 study in under-fives. Biomarin touted a placebo-adjusted 0.92cm/year increase in annualised growth velocity – below the 1.57cm/year seen in a separate trial in patients aged five and over, for whom Voxzogo is already approved. What is more, the former figure included so-called “sentinel subjects” – patients who received open-label Voxzogo at the start of each new age group cohort. Biomarin did not disclose growth velocity results for randomised patients only, suggesting that these were “less good, and/or more fraught with noise”, as Stifel analysts put it. The company did give more details of Z-scores, a measure of how much a given value deviates from the mean, used to track the growth of very small children. However, the Z-score was less impressive when only randomised patients were included. Stifel reckons the latest data are “probably enough” for label expansion, but without more information this looks tough to call.