To read the blog post from NHS England, click here.
The NHS-Galleri trial, which started enrolling participants in 2021, was designed to inform implementation of the Galleri test as a national screening programme if recommended by the UK National Screening Committee on the basis of the final study results, which are expected in 2026. The trial was designed with three consecutive years of screening in order to achieve the primary endpoint, which is the absolute reduction in the number of late stage (Stage III and IV) cancer diagnoses.
As described in March, NHS England planned to look at a snapshot of selected first year results (the prevalent screening round with one year of follow-up) from the NHS-Galleri trial to assess whether there is enough compelling early evidence to initiate a pilot of Galleri within the NHS setting. This first year analysis was conducted solely to determine whether there was an early sign of compelling patient benefit, sufficient for the NHS to accelerate an implementation before the final study readout. Three robust, ambitious and pre-specified criteria were assessed: the positive predictive value (PPV) of the Galleri test, the number of late-stage cancers detected and the total number of cancers detected in the intervention arm compared with the control arm. Notably, this was not an interim analysis of the trial primary endpoint, as that analysis requires data from all three rounds of screening.
Based on a snapshot of first-year results from the ongoing NHS-Galleri trial, NHS England has decided to await final results from the three-year trial before determining whether to initiate a pilot of the Galleri test in the NHS.
Advised by a multidisciplinary expert panel, NHS England determined that, while the early analysis showed that the assessed clinical performance of Galleri was very promising — consistent with or better than Galleri’s clinical performance observed in previous published studies — there is not yet enough early compelling evidence to accelerate implementation through a pilot programme at this stage.
As described by the NHS, “Committing to accelerate implementation of the test in the NHS at scale would have been an exceptional step, requiring exceptional data after just one year, and while what we have seen is very promising, the data so far do not support moving at such a fast pace.” Instead, NHS England will make a decision on the basis of the final trial results, expected in 2026.
This early look at certain selected metrics provides only a limited view. As demonstrated in previous cancer screening trials, results from the first screening round do not always reflect the final results, especially for reduction in late stage diagnosis. In the US National Lung Screening Trial (NLST) for example, participants underwent three annual screenings. Ultimately, the trial demonstrated a significant relative reduction in mortality for those who received low-dose CT screening. However, no reduction in stage IV cancers was observed after the first year of screening. This is because a prevalent screening round often includes many asymptomatic cancers in later stages that have not been ‘swept out’ by that first year of screening. In NLST, the stage IV incidence was reduced after that first year of screening – and was maintained throughout the follow-up period.
The NHS-Galleri trial – like numerous other cancer screening trials – was designed with multiple years of screening, and thus it remains important to complete the trial and evaluate the primary objective and endpoints at the end of the study.
Diagnosing more cancers before they present symptomatically is central to GRAIL’s mission and is also a core part of NHS England’s Long Term Plan to transform cancer outcomes. NHS England has reiterated its belief that multi-cancer early detection is an important innovation that could become a core component of its ambition to reduce late-stage cancer diagnosis in the future.
The NHS-Galleri trial completes appointments with the final blood samples being taken in July 2024 and the ongoing involvement of participants (and any subsequent diagnostic follow up in the NHS) remains critical to fully understanding the test’s potential benefit at population scale. We await the final results and I would like to reiterate my sincere appreciation to the more than 140,000 participants who generously volunteered to take part in the trial to contribute to, and advance, this valuable field of science and medicine.