The serious adverse events involved apparent lactic acidosis, a dangerous buildup of lactic acid. The two patients concerned were administered CS-917 in combination with metformin, which has itself been associated with lactic acidosis.
A second study involving administration of a relatively high dose of CS-917 to evaluate timing of dose administration has also been stopped, and a third study evaluating various doses of CS-917 administered as a single agent over three months is under review.
Metabasis said that it will work with Sankyo, investigators and other experts to evaluate clinical data in an effort to fully understand the implications of these findings for the development of CS-917.
“Clearly we are disappointed with this news from our partner Sankyo,” said Dr Paul Laikind, chairman, CEO and president of Metabasis. “Although the efficacy data on CS-917 is promising, these adverse events raise safety concerns for CS-917 that we and our partner need to fully and carefully evaluate. We believe that Sankyo made the appropriate decision by halting the two studies and carefully reviewing the three-month study before administering CS-917 to any additional patients.”