In another PhIII, Albert Bourla continues to build case for a once-flopped GHD drug
A growth hormone treatment that’s seen a turbulent path may finally be reaching the light at the end of the tunnel.
Pfizer and Opko Health announced Thursday morning that their once-weekly somatrogon met its primary endpoint in a Phase III study, beating out Pfizer’s old daily Genotropin (somatropin) therapy in the perception of treatment burden. The news follows positive Phase III data from 2019 showing clinical benefits, as well as a previous flop near the end of 2016 measuring the program against a sugar pill.
Aimed at treating children with growth hormone deficiency older than 3 and younger than 18, somatrogon improved the average score on a common GHD test, known as the Life Interference Questionnaire, after 12 weeks on each treatment. The 87 patients were randomized into two “sequences” — one taking Genotropin followed by somatrogon and the other taking somatrogon followed by Genotropin.
In the topline results revealed Thursday, taking somatrogon resulted in an average score of 8.63 while Genotropin’s average was 24.13. The questionnaire is a composite score taking into account several factors such as ease of use, convenience and willingness to continue treatment, among others. Like in golf, lower scores are better.
The estimated difference between the two arms, negative-15.49, reached a p-value lower than 0.0001. Secondary endpoints also showed that patients on somatrogon showed an overall benefit in treatment experience over Genotropin.
GHD therapy has centered around daily injections since their introduction several decades ago. Pfizer’s Genotropin itself has been on the market for nearly a quarter century, and while it was once a franchise drug, biosimilars have flooded the development space. The pharma company likely wants to stay ahead of the competition, hence the partnership with Opko.
As of late 2019, the leader in the space is Norditropin, a growth hormone from Novo Nordisk that uses the same basic ingredient as Genotropin. The Danish company sells the treatment with a kid-friendly self-injectable pen.
It’s been a long road for somatrogon, which in 2016 flopped a Phase III trial showing that the candidate did not show an improvement in change in trunk fat mass from baseline to 26 weeks. At the time, Opko insisted the result was caused by “one or more outliers” that affected the outcome, and in 2017 followed up with an analysis saying they were the underlying reason for the fail.
Things began looking up toward the end of 2019, when the companies released data saying that somatrogon showed a better increase in height velocity than Genotropin. The trial arm showed a velocity of 10.12 cm/year, edging out the older drug’s 9.78 cm/year.
Pfizer originally partnered with Opko in 2014 to the tune of $295 million upfront and up to $275 million more in regulatory milestones.
Last month, Pfizer CEO Albert Bourla pinned peak sales estimates on each of the company’s late-stage programs, a step most executive teams might be reluctant to take. Though somatrogon wasn’t listed among the top projected blockbusters, Bourla pegged it for the $500 million to $1 billion category.