A phase 3 liver cancer trial of Transgene and SillaJen’s oncolytic virus has been stopped early for futility. The setback sent the share prices of the companies downward and added to doubts about the effectiveness of oncolytic viruses.
Transgene’s partner, SillaJen, moved Pexa-Vec into phase 3 on the strength of data from a 30-patient study that linked the higher dose of the oncolytic virus to a median overall survival of 14.1 months. That is longer than the 10.7 months on the U.S. label of Bayer’s Nexavar, raising hopes that Pexa-Vec could improve on current treatment options.
The latest update quashes those hopes. Neither SillaJen nor Transgene have shared data from the trial, but whatever the independent data committee saw at the interim review was bad enough to prompt a recommendation that the study is stopped for futility.
SillaJen designed the 600-subject trial to show whether giving Pexa-Vec to first-line liver cancer patients before starting them on Nexavar could improve overall survival over the Bayer drug alone. The data committee decided that, on the basis of interim data, Pexa-Vec was unlikely to drive the desired improvement in overall survival.
There were signs ahead of the update that Pexa-Vec may struggle to beat Nexavar in a larger clinical trial. While the Nexavar label carries a median overall survival of 10.7 months, the drug recorded a figure of 12.3 months in a more recent head-to-head against Merck’s Lenvima. Given the chance Pexa-Vec may struggle to achieve a 14.1-month overall survival when tested in more patients, the data on Nexavar suggested the oncolytic virus may fail to beat Bayer’s drug.
Shares in Transgene fell about 19% in the immediate aftermath of the news. The failure is a bigger deal for SillaJen, which had gained a $3 billion market cap largely on the potential of Pexa-Vec. Shares in SillaJen fell 30% following the news.
The failure could have implications beyond Transgene and SillaJen. Leading drug developers such as Merck and Johnson & Johnson have piled into the oncolytic virus market over the past two years, in part because of the potential for the modality to turn cold tumors hot. But there are limited clinical data to support the use of oncolytic viruses.