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Adding injections of an engineered pox virus before standard liver cancer treatment did not help and the results were worse than the control arm, so the trial was stopped early.
Randomised, open-label phase 3 trial at 142 sites in 16 countries of pexastimogene devacirepvec, an oncolytic and immunotherapeutic vaccinia virus, injected into the tumour and followed by sorafenib, against sorafenib alone, in advanced hepatocellular carcinoma with no prior systemic treatment. 459 patients were randomised between December 2015 and the interim analysis in August 2019.
At the interim analysis median overall survival was 12.7 months with the sequence and 14.0 months with sorafenib alone, which led to early termination. Median time to progression was 2.0 months against 4.2 months. Objective response was 19.2 per cent against 20.9 per cent and disease control 50.0 per cent against 57.3 per cent. Serious adverse events occurred in 53.7 per cent against 35.5 per cent, liver failure being the commonest in both arms.
Earlier phase 2 work had reported a dose-related survival difference after intratumoural injection of the same virus, which is the reason the phase 3 was run.
A phase 2 signal that looked like a survival benefit, tested in 459 patients, turned out to be nothing, and delaying effective systemic treatment to give the virus first made outcomes worse. The authors' own conclusion is that the arrival of checkpoint inhibitors should direct any further development of oncolytic virus strategies, which is a polite way of saying this design is finished.