US biotech Versartis saw more than 80% wiped off its share price ahead of the weekend after its growth hormone deficiency drug somavaratan failed a phase III trial.
The long-acting human growth hormone (hGH) product had been billed as a successor to current hGH products – which are given daily – that make-up a $3bn market. Somavaratan requires dosing only every two weeks and offers other advantages such as room temperature storage, but the results of the VELOCITY trial put its future in doubt.
Somavaratan – which is Versartis’ lead and only clinical programme – was unable to meet the primary objective of non-inferiority to Pfizer’s widely used Genotropin (somatropin) brand of hGH, which according to analysts seems to have been caused by the comparator drug working at the high end of expectations.
Versartis’ drug worked pretty much as expected, but didn’t hit the main endpoint in the trial of being as good as Genotropin on an intention-to-treat basis – bringing in all randomised patients regardless of issues such as non-compliance, dropouts etc. The drug worked as well as Genotropin among patients who completed the protocol as directed – but that is unlikely to be enough to convince the FDA of its merits.
Aside from the trial efficacy miss, other issues have plagued somavaratan during its development, including safety concerns that prompted an FDA clinical hold in 2015, and the development of neutralising antibodies – which reduce the effectiveness of treatment – in some patients. It’s not the first long-acting hGH to miss the mark in trials – earlier this year Pfizer and Opko’s once-weekly candidate also failed a phase III trial.
For now, Versartis is playing its cards close to its chest, telling investors that it is “continuing to thoroughly review the results to gain greater insight into the trial outcome [and] plans to provide a corporate update later this year”.
Versartis disappointment has proved a fillip for rival company Ascendis Pharma, which is developing an alternative long-acting hGH product that required injecting once a week. Ascendis’ candidate is due to generate phase III results in the latter half of 2018, setting up possible regulatory filings in early 2019.
Versartis’ drug was expected to pair a dosing frequency with an earlier launch, setting up potential blockbuster sales, and with its setback much of the attention is now focused on Ascendis’ candidate. It’s worth noting however that hGH behemoth Novo Nordisk also has a once-weekly candidate called somapacitan in phase III in Japan and Europe, although that project seems to be in earlier-stage development in the US.