The FDA has lifted the partial clinical hold on Northwest Biotherapeutics’ phase 3 cancer vaccine trial. The action comes 18 months after the FDA suspended the screening of new patients in the trial, and potentially just months before Northwest Bio hits the thresholds needed to wrap up the study.
With Northwest Bio having decided to close enrollment 17 subjects short of its target, the lifting of the partial clinical hold won’t trigger renewed recruitment in the trial. But the FDA action clears a regulatory concern for Northwest Bio as it nears the end of the long-running brain cancer trial, the first version of which was submitted to ClinicalTrials.gov in 2002.
The study has passed its threshold of 248 disease-progression events—the primary endpoint—and is nearing the 233 patient deaths that need to occur before it starts analyzing the overall survival secondary endpoint.
Northwest Bio thinks it will take several months for the trial to reach the overall survival threshold, and that the routine checks and cleaning that are performed before the database is closed will be “a multi-month process.” As such, it is unclear when Northwest Bio will present data from the trial.
The history of delays and tweaks to the trial have contributed to Northwest Bio’s financial reserves running low—it had $802,000 in cash at the end of September—but those involved in the study see a positive to its continuation.
“The longer it takes for PFS and OS events to accrue, the better the patients in the trial are doing,” Dr. Linda Liau, the principal investigator of the study, said in a statement.
While it is true that a slower rate of disease progression and deaths are positives for patients in the study in general, this doesn’t necessarily mean Northwest Bio's cancer vaccine DCVax is helping patients. The latest evidence of the risk of conflating time to hit PFS or OS thresholds and the likelihood of study success arrived hours before Northwest Bio’s release when Innate Pharma posted data on a phase 2 trial of its immuno-oncology asset.
That trial was slated to wrap up in June but continued for months more. Some observers saw the overrun as evidence lirilumab was slowing the rate of disease progressions. However, top-line data presented this week showed lirilumab failed to outperform the placebo.