The Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2023 annual meeting (9–13 September, Copenhagen, Denmark) played host to another FIRST@CIRSE session, which saw first data releases from various interventional radiology trials. Mishal Mendiratta-Lala (University of Michigan, West Bloomfield, USA) presented “much awaited” data from the #HOPE4LIVER trial which demonstrated the “successful, non-invasive destruction” of liver tissue using hepatic histotripsy.
Mendiratta-Lala, providing key background for the study, began by highlighting limitations of locoregional therapies for primary and metastatic hepatic malignancies, including the “degree of invasiveness, inability to treat near clinical structures, lack of real-time visualisation during treatment, collateral damage, and variability in local tumour control”.
“If we had technology which could address these concerns, this could be a major clinical advancement in the treatment of liver tumours,” the presenter averred, then introduced histotripsy—a non-thermal, mechanical process of focused ultrasound through precisely controlled acoustic cavitation.
In order to evaluate the efficacy of histotripsy, Mendiratta-Lala proceeded to describe their prospective, multicentre, single-arm investigational device exemption (IDE) trial, using the HistoSonics System (HistoSonics) for the treatment of liver tumours. Two iterations of the study were carried out, in Europe and the USA respectively, comprised of six European and eight US sites.
Hepatic histotripsy was performed on 44 tumours in the first 40 evaluable subjects enrolled between the two trials, with a primary endpoint of technical success at ≤36 hours post-index procedure, or of 70%, and a primary safety endpoint of no major complications up to 30-days post procedure. The speaker underlined that positive results were required for both primary endpoints for the trial to be considered “successful”.
Of their technical success endpoint, the speaker told CIRSE delegates that “based on the 44 treated tumours, 42 were successfully treated giving us a primary efficacy of 95.5%.” Mendiratta-Lala pointed out that the two tumours that were not successfully treated were due to “user error, not device error”. Concerning their safety endpoint, Mendiratta-Lala explained that the investigators encountered three complications (6.8%), due to the “known risks of focal liver therapies and not unique to histotripsy,” a result which still “[met] the pre-specified performance goal of less than 25%”.
Noting the limitations of their study, Mendiratta-Lala emphasised their “small, heterogeneous patient cohort”, and made clear that the majority of this patient population were recorded to be at an advanced stage of disease, and although their findings “show the effect of histotripsy tissue destruction,” its direct effect on the disease process “was not evaluated”. The presenter concluded however, that both safety and effectiveness endpoints were met in the #HOPE4LIVER trials, “demonstrating successful, non-invasive destruction of liver tissue via histotripsy”.