Pfizer’s growth hormone falls short

It’s unusual that one company’s trial hit boosts the stock of its rival. Shares in Ascendis Pharma closed up 5% yesterday after Pfizer’s long-acting growth hormone project somatrogon, formerly known as Lagova, succeeded in phase III – but only showed non-inferiority to daily injections, failing to match the superiority demonstrated by Ascendis’s TransCon hGH in March (Ascendis shoots higher on pivotal win, March 4, 2019). In the trial, 224 pre-pubertal patients took either a weekly dose of somatrogon, which is being developed jointly by Pfizer and Opko Health, or daily generic growth hormone. The treatment difference in height velocity was 0.33cm/year, which might be enough to allow approval of somatrogon, but is unlikely to convince payers to shell out for the therapy. Safety was comparable to the generic, Pfizer said, though data on IGF-1 levels, BMI and immunogenicity, all of which are essential to fully understanding the drug’s profile, were not detailed. More information might come at the Endo meeting next March, but for now it appears that Ascendis’s drug is the one to watch. According to EvaluatePharma’s sellside consensus, TransCon hGH is forecast to have sales of $1.2bn in 2024, compared with just $16m for somatrogon.

Cross-trial comparison of extended-release growth hormones 
Company Pfizer/Opko Ascendis
Trial Unnamed trial Height
Project Somatrogon Daily hGH TransCon hGH Daily hGH
Annualised height velocity at 52 weeks (cm/yr) 10.12 9.78 11.2 10.3
Source: company press releases.

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