Mr John Fallon, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This large open labelled multi-centre randomised control trial is an exciting development in the field of liver HMP. The key strength of this work is that 43% (n=27) of the HMP-O2 livers had continuous perfusion, having been placed on device at the donor. This is the first trial in liver HMP to do this and is an important development. Made possible by Organ Recovery Systems portable Lifeport Liver device, especially considering 81% travelled by air, a current limitation of the portable NMP devices. They demonstrated a nonsignificant reduction in EAD with 11% in HMP-O2 and 16% in SCS, while the finding is not significant it is in keeping with the 5 other published RCTs on HMP liver. The lack of significance may derive from the fact that within the intervention group only 24% were ECDs (including 5 DCD), upon sub-group analysis of these ECDs they find the reduction of EAD to be significant (20% in HMP-O2 and 33.3% in SCS p=0.004). This is in keeping with previous large RCTs that the beneficial effects of HMP-O2 are amplified in the ECD cohort, especially in DCDs seen in Rijn et al’s 2021 trial published in the New England Journal who perfused only DCD livers. None of their secondary outcomes reach significance, but with PNF only occurring in the SCS group with 3 patients and a further 2 (n=5 6.8%) went on to require re-transplant also due to ischaemic cholangiopathy. In HMP-O2 only 1 required retransplant, this was due to HAT. Biliary complications were nearly double in the SCS group (26.4% vs 12.7%) which is impressive, but again this failed to reach significance. The trends are encouraging, but the lack of significance is disappointing, the trial having not been powered for overall EAD rates. An increase cohort size and a focus on EADs could have led to more dramatic results with potentially significance in many of the outcomes. An interesting note is the preservation fluid used in HMP-O2 was Vasosol, a UW-like solution with the addition of nitric oxide donors and vasodilators, this is the first HMP RCT across all organs to utilise this solution and could, in part be responsible for some of the beneficial trends. Unfortunately, the study was not sufficiently powered to compare continuous HMP-O2 with end-ischaemic HMP-O2 and SCS, the overall storage duration being comparable, but the percentage of that time being perfusion obviously being highest in the continuous group. They demonstrate safety and non-inferior efficacy of a novel portable device, which as it becomes more popular and people become more familiar with placing livers on device at retrieval more data should emerge on continuous HMP-O2, this trial was an important step.
Aims:
To assess if HMP-O2 improves liver transplant outcomes compare to cold storage.
Interventions:
Livers were randomised to intervention, which was HMP-O2 on the Lifeport Liver Transporter device, perfused with Vasosol, or control, which was static cold storage.
Participants:
179 adult whole liver transplant recipients.
Outcomes:
The primary outcome was early allograft dysfunction (EAD) as defined by the Olthoff criteria. Secondary outcome measures were PNF, AKI, graft survival, biliary complications. Vascular complications and death. Additional exploratory outcomes were hospital LOS, ICU LOS, lactate clearance, bleeding, incisional hernia and SAEs.
Follow Up:
12 months
BACKGROUND AND AIMS:
In liver transplantation, cold preservation induces ischemia, resulting in significant reperfusion injury. Hypothermic oxygenated machine perfusion (HMP-O 2 ) has shown benefits compared to static cold storage (SCS) by limiting ischemia-reperfusion injury. This study reports outcomes using a novel portable HMP-O 2 device in the first US randomized control trial.
APPROACH AND RESULTS:
The PILOT trial (NCT03484455) was a multicenter, randomized, open-label, noninferiority trial, with participants randomized to HMP-O 2 or SCS. HMP-O 2 livers were preserved using the Lifeport Liver Transporter and Vasosol perfusion solution. The primary outcome was early allograft dysfunction. Noninferiority margin was 7.5%. From April 3, 2019, to July 12, 2022, 179 patients were randomized to HMP-O 2 (n=90) or SCS (n=89). The per-protocol cohort included 63 HMP-O 2 and 73 SCS. Early allograft dysfunction occurred in 11.1% HMP-O 2 (N=7) and 16.4% SCS (N=12). The risk difference between HMP-O 2 and SCS was -5.33% (one-sided 95% upper confidence limit of 5.81%), establishing noninferiority. The risk of graft failure as predicted by Liver Graft Assessment Following Transplant score at seven days (L-GrAFT 7 ) was lower with HMP-O 2 [median (IQR) 3.4% (2.4-6.5) vs. 4.5% (2.9-9.4), p =0.024]. Primary nonfunction occurred in 2.2% of all SCS (n=3, p =0.10). Biliary strictures occurred in 16.4% SCS (n=12) and 6.3% (n=4) HMP-O 2 ( p =0.18). Nonanastomotic biliary strictures occurred only in SCS (n=4).
CONCLUSIONS:
HMP-O 2 demonstrates safety and noninferior efficacy for liver graft preservation in comparison to SCS. Early allograft failure by L-GrAFT 7 was lower in HMP-O 2 , suggesting improved early clinical function. Recipients of HMP-O 2 livers also demonstrated a lower incidence of primary nonfunction and biliary strictures, although this difference did not reach significance.
Mr John O'Callaghan, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This well-written report details an analysis of perfusate samples collected during the COMPARE study, an RCT comparing oxygenated with non-oxygenated machine perfusion. Mass spectrometry was used to analyse the proteomic make up of the perfusate fluid. During hypothermic machine perfusion, proteins enter the perfusate system, increasing over time. The authors explored the relation between perfusate proteins and clinical outcomes, with some indication that outcomes such as acute rejection and kidney function at 12 months.
Aims:
The aim of this study was to provide mechanistic insight into biological alterations that occur in deceased donor kidneys during standard nonoxygenated versus oxygenated hypothermic machine perfusion (HMP), using perfusate samples collected in the COMPARE study.
Interventions:
In the COMPARE trial, pairs of kidneys donated following circulatory death were randomly assigned to receive either oxygenated HMP or nonoxygenated HMP.
Participants:
210 perfusate samples.
Outcomes:
The main outcome of this paper was to identify protein changes across durations of perfusion and in relation to 12-month estimated glomerular filtration rate (eGFR).
Follow Up:
12 months
OBJECTIVE:
To provide mechanistic insight into key biological alterations in donation after circulatory death kidneys during continuous pefusion we performed mass spectrometry profiling of perfusate samples collected during a phase 3 randomized double-blind paired clinical trial of hypothermic machine perfusion with and without oxygen (COMPARE).
BACKGROUND:
Despite the clinical benefits of novel perfusion technologies aiming to better preserve donor organs, biological processes that may be altered during perfusion have remained largely unexplored. The collection of serial perfusate samples during the COMPARE clinical trial provided a unique resource to study perfusate proteomic profiles, with the hypothesis that in-depth profiling may reveal biologically meaningful information on how donor kidneys benefit from this intervention.
METHODS:
Multiplexed liquid chromatography-tandem mass spectrometry was used to obtain a proteome profile of 210 perfusate samples. Partial least squares discriminant analysis and multivariate analysis involving clinical and perfusion parameters were used to identify associations between profiles and clinical outcomes.
RESULTS:
Identification and quantitation of 1716 proteins indicated that proteins released during perfusion originate from the kidney tissue and blood, with blood-based proteins being the majority. Data show that the overall hypothermic machine perfusion duration is associated with increasing levels of a subgroup of proteins. Notably, high-density lipoprotein and complement cascade proteins are associated with 12-month outcomes, and blood-derived proteins are enriched in the perfusate of kidneys that developed acute rejection.
CONCLUSIONS:
Perfusate profiling by mass spectrometry was informative and revealed proteomic changes that are biologically meaningful and, in part, explain the clinical observations of the COMPARE trial.
Mr John Fallon, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This small, randomised control trial looked at early post-transplant outcomes after dHOPE compared with SCS in an undifferentiated group of DBD livers. They found no significant difference in their primary outcome of MEAF score between the two groups. They also found no difference in all grades of complications, mortality, post-reperfusion syndrome rates, comprehensive complications index (CCI), L-GrAFT7, or the other non-prespecified secondary outcomes, ITU stay, PNF, EAD and EASE score. The lack of significant benefits were similar to that seen in Schlegal et al’s recent larger multicentre randomised trial who used CCI as their primary outcome. In this study, only 26 livers were in the intervention group and they were hoping to detect a MEAF score reduction of 1.5, a delta in primary outcome of no specific significance. The small number and lack of power calculation has meant there is significant risk of falsely negative findings. They performed a sub-group analysis, dividing the livers arbitrarily by DRI, with a cut-off of >1.7 as becoming ‘high-risk’, within this group dHOPE caused a significant reduction in MEAF score (4.92 vs 6.31, p=0.037) and in CCI (p=0.05). This led the authors to conclude that routine use of dHOPE is not recommended in DBD livers, only for those deemed ‘high-risk’. Again, caution is needed with the conclusion that there is no benefit in lower risk livers, given only 12 and 14 livers were in the DRI ≤1.70 and DRI >1.70 respectively. The trial is appropriately randomised, but was not blinded due to logistical reasons, which with a device trial of this nature is challenging. There is no information given regarding drop-outs or protocol breaches. The area of investigation is interesting and a valid research question, however, this trial is not sufficiently powered to be relied upon as a negative study. They have highlighted a potential difference in benefit, or lack there of depending on the quality of donor, and future studies should consider this and power specifically for sub-group analysis.
Aims:
To assess if dual hypothermic oxygenated perfusion (dHOPE) prior to transplantation improves the Model for Early Allograft Function (MEAF) score during the 72 hours following transplant compared with static cold storage (SCS).
Interventions:
The intervention group received at least 2 hours of dHOPE prior to transplantation, and the control group underwent standard SCS.
Participants:
104 adult whole liver transplant recipients from donation after brainstem death.
Outcomes:
The primary outcome was MEAF score during the 72 hours post transplant. Secondary outcomes were complications over 90-days, 7-day liver graft assessment following transplantation (L-GrAFT7), post-reperfusion syndrome rate, comprehensive complication index (CCI) and mortality.
Follow Up:
Not reported
OBJECTIVE:
To assess whether end-ischemic hypothermic oxygenated machine perfusion (HOPE) is superior to static cold storage (SCS) in preserving livers procured from donors after brain death (DBD).
BACKGROUND:
There is increasing evidence of the benefits of HOPE in liver transplantation, but predominantly in the setting of high-risk donors.
METHODS:
In this randomized clinical trial, livers procured from DBDs were randomly assigned to either end-ischemic dual HOPE for at least 2 hours or SCS (1:3 allocation ratio). The Model for Early Allograft Function (MEAF) was the primary outcome measure. The secondary outcome measure was 90-day morbidity (ClinicalTrials. gov, NCT04812054).
RESULTS:
Of the 104 liver transplantations included in the study, 26 were assigned to HOPE and 78 to SCS. Mean MEAF was 4.94 and 5.49 in the HOPE and SCS groups ( P =0.24), respectively, with the corresponding rates of MEAF >8 of 3.8% (1/26) and 15.4% (12/78; P =0.18). Median Comprehensive Complication Index was 20.9 after transplantations with HOPE and 21.8 after transplantations with SCS ( P =0.19). Transaminase activity, bilirubin concentration, and international normalized ratio were similar in both groups. In the case of donor risk index >1.70, HOPE was associated with significantly lower mean MEAF (4.92 vs 6.31; P =0.037) and lower median Comprehensive Complication Index (4.35 vs 22.6; P =0.050). No significant differences between HOPE and SCS were observed for lower donor risk index values.
CONCLUSION:
Routine use of HOPE in DBD liver transplantations does not seem justified as the clinical benefits are limited to high-risk donors.
Mr Keno Mentor, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This unblinded randomised trial compared the outcomes of liver transplantation following either normothermic machine perfusion (NMP) or static cold storage (SCS). The study employed a ‘device-to-donor’ methodology where the Organox metra device is transported to the site of organ retrieval, which the authors highlight is logistically more challenging. 266 livers were included in the analysis. The primary endpoint was early allograft dysfunction (EAD), defined as abnormal liver parameters 7 days after transplantation. There was no significant difference in EAD between the 2 groups. Although the difference in EAD was numerically greater when using an as treated or sub-group analysis of higher risk groups (high DRI, DCD donor), this to failed to reach statistical significance. The authors reached conclusions similar to that of previous European trials – NMP is a safe modality and shows potential to improve outcomes in marginal organs.
Expert Review
Reviewer:
Mr Simon Knight, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Clinical Impact Rating
3
Review:
The use of machine preservation technologies in liver transplantation has been gaining pace over recent years, with centres using a mixture of normothermic machine perfusion (NMP), hypothermic oxygenated machine perfusion (HOPE) and normothermic regional perfusion (NRP). Machine preservation has the potential to resuscitate the liver, reverse retrieval-related injury, allow longer safe preservation times and enable viability assessment prior to implant. In particular, NMP allows functional assessment of the liver with well-defined parameters predicting early allograft function (1). The first multicentre randomised controlled trial (RCT) of normothermic machine perfusion in Europe was published in 2018, and demonstrated a significant (50%) reduction in the incidence of early allograft dysfunction (EAD) in machine perfused livers, despite longer preservation times (2). These results were replicated in a US study (using a different NMP device), which also demonstrated a significant reduction in the incidence of EAD with NMP (3). Whilst not specifically designed to demonstrate differences in organ utilisation, both studies also showed a reduction in organ discard rates, particularly for donation after cardiac death (DCD) livers. In a recent publication in the Annals of Surgery, Chapman and colleagues report the results of the large multicentre US experience of NMP (4). They used a protocol very similar to that followed in the European RCT. Livers were randomised to either conventional static cold storage (SCS) or NMP, with perfusion initiated at the donor hospital and the liver transported on the device to the implanting centre. In contrast to the European study, the trial did not meet its primary endpoint of demonstrating an overall reduction in EAD. Per-protocol analysis showed similar trends to the prior European and US studies, with greater reduction in EAD rates seen with NMP in DCD and high donor-risk index (DRI) subgroups. Interestingly, there was evidence of a learning curve, with a reduction in EAD rates in the NMP arm following enhanced training during the study. Unlike the previous two RCTs, there was no difference in transplant rate between the arms. One important point to note is that all three RCTs used NMP in a “device-to-donor” configuration, with initiation of NMP at the donor hospital and transport on the device. This has significant logistical challenges, particularly in countries like the US where travel distances are longer and travel by plane is more common. In reality, most centres using NMP routinely in the UK and Europe are using NMP in a “back-to-base” configuration, with transport of the liver under SCS and initiation of perfusion in the recipient centre. Whilst small studies suggest that this does not compromise outcomes for the majority of livers (5), there is no large-scale RCT evidence to support the back-to-base NMP perfusion strategy that many centres are employing. Overall, whilst this study demonstrates a smaller effect size than previous RCTs, it does confirm that the technology is safe and that the main benefit of this technology appears to be for more marginal (high DRI and DCD) livers. References 1. Watson CJE, Gaurav R, Fear C et al. Predicting Early Allograft Function After Normothermic Machine Perfusion. Transplantation 2022; 106: 2391. 2. Nasralla D, Coussios CC, Mergental H et al. A randomized trial of normothermic preservation in liver transplantation. Nature 2018; 557: 50. 3. Markmann JF, Abouljoud MS, Ghobrial RM et al. Impact of Portable Normothermic Blood-Based Machine Perfusion on Outcomes of Liver Transplant: The OCS Liver PROTECT Randomized Clinical Trial. JAMA Surgery 2022; 157: 189. 4. Chapman WC, Barbas AS, D’Alessandro AM et al. Normothermic Machine Perfusion of Donor Livers for Transplantation in the United States - A Randomized Controlled Trial. Annals of Surgery 2023; 5. Ceresa CDL, Nasralla D, Watson CJE et al. Transient Cold Storage Prior to Normothermic Liver Perfusion May Facilitate Adoption of a Novel Technology. Liver Transplantation: Official Publication of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society 2019; 25: 1503.
Aims:
The aim of this study was to investigate the effectiveness of normothermic machine preservation (NMP) versus static cold storage (SCS) in the prevention of preservation-related graft injury.
Interventions:
Donor livers were randomised to undergo either NMP or SCS.
Participants:
383 donor livers were randomised out of which 266 donor livers were transplanted.
Outcomes:
The primary endpoint was early allograft dysfunction (EAD). Secondary endpoints included graft survival, patient survival, incidence of postreperfusion syndrome, biochemical liver function, biliary complications, histological evidence of ischemia-reperfusion injury, feasibility and safety, health economics and organ utilization.
Follow Up:
12 months
OBJECTIVE:
To compare conventional low-temperature storage of transplant donor livers [static cold storage (SCS)] with storage of the organs at physiological body temperature [normothermic machine perfusion (NMP)].
BACKGROUND:
The high success rate of liver transplantation is constrained by the shortage of transplantable organs (eg, waiting list mortality >20% in many centers). NMP maintains the liver in a functioning state to improve preservation quality and enable testing of the organ before transplantation. This is of greatest potential value with organs from brain-dead donor organs (DBD) with risk factors (age and comorbidities), and those from donors declared dead by cardiovascular criteria (donation after circulatory death).
METHODS:
Three hundred eighty-three donor organs were randomized by 15 US liver transplant centers to undergo NMP (n = 192) or SCS (n = 191). Two hundred sixty-six donor livers proceeded to transplantation (NMP: n = 136; SCS: n = 130). The primary endpoint of the study was "early allograft dysfunction" (EAD), a marker of early posttransplant liver injury and function.
RESULTS:
The difference in the incidence of EAD did not achieve significance, with 20.6% (NMP) versus 23.7% (SCS). Using exploratory, "as-treated" rather than "intent-to-treat," subgroup analyses, there was a greater effect size in donation after circulatory death donor livers (22.8% NMP vs 44.6% SCS) and in organs in the highest risk quartile by donor risk (19.2% NMP vs 33.3% SCS). The incidence of acute cardiovascular decompensation at organ reperfusion, "postreperfusion syndrome," as a secondary outcome was reduced in the NMP arm (5.9% vs 14.6%).
CONCLUSIONS:
NMP did not lower EAD, perhaps related to the inclusion of lower-risk liver donors, as higher-risk donor livers seemed to benefit more. The technology is safe in standard organ recovery and seems to have the greatest benefit for marginal donors.
Mr John Fallon, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This small unblinded randomised trial was conducted in a single high volume transplant centre in China by the group who have been pioneering the ischaemia-free liver transplant technique since its fist publication in 2018. Images and videos of their technique have been included in their 3 publications on their reports and protocols. The IFLT cohort was n=32 and the CLT n=33, of these 2 (6%) in the IFLT experience EAD and 8 (24%) in the CLT (p=0.044) which was the primary endpoint. In some of the secondary endpoints they found significant improvement with IFLT: peak ALT and ASK at 7 days, total bilirubin, post-op lactate positive perfusate microbial culture and non-anastomotic strictures at 12 months. When scrutinising these strictures, there were 2 in IFLT (one mild and one moderate) and 9 in CLT (five mild and four moderate) none of which required intervention. The marked reduction in post-reperfusion syndrome is important 3 (9%) in IFLT and 21 (64%) in CLT given the risk of post-reperfusion cardiac arrest. They found no significant differences in primary non-function, over-all hospital stay, anastomotic stenosis (though the rate was higher in IFLT) and, graft and patient survival. They present an impressive success given the complexity of the procedure, however this is its key limitation. Despite the improvement in EAD, strictures and post-reperfusion syndrome there was no measurable benefit in patient or graft survival within the first year and none of the strictures require intervention. It was done in a set of low risk DBD donors, a cohort in which similar benefits have been seen with NMP alone. There are technical limitations, it was performed with a liver assist device which is not transportable, thus donor and recipient must be in the same location. The technique is of interest and a great technical achievement, but a study of larger numbers with a wider range of DBD donors and longer-term follow-up is required.
Expert Review
Reviewer:
Mr John O'Callaghan, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Review:
This is a very interesting randomised controlled trial in liver transplantation that has the potential to significantly change practice and improve transplant outcomes. 68 liver transplant recipients from donation after brain death were randomised to standard treatment or for an “Ischemia-Free Liver Transplant” (IFLT). The trial was conducted at a single hospital in China. The study was adequately randomised, but the clinical team could not be blinded to the intervention, understandably. For the intervention group, the Liver Assist device (Organ assist, The Netherlands) was used to establish in situ normothermic perfusion. The liver was then procured and moved to the reservoir of the Liver Assist for ex situ normothermic machine perfusion and moved to the recipient locality for transplant. For the liver implantation to the recipient, the anastomoses of the inferior vena cava, portal vein, and hepatic artery were performed under continuous in situ normothermic machine perfusion. Machine perfusion was discontinued after the donor liver had been revascularized. Then the biliary tract was reconstructed. There was therefore zero cold ischemic time for the IFLT group. Mean cold ischaemic time in the standard care group was approximately 7 hours, and mean normothermic perfusion time in the IFLT group was approximately 7 hours. The primary outcome was Early Allograft Dysfunction (EAD) and this was significantly reduced by IFLT (6% versus 24%), as were peak ALT, AST and bilirubin levels. Post-reperfusion syndrome was dramatically reduced, from 64% to 9%. Non-anastomotic biliary strictures were also significantly reduced (8% versus 36%), although this was recorded as seen on protocol MRCP. This clinical trial has shown a dramatic reduction in the ischemia reperfusion injury of transplant livers through the novel use of technology to remove the cold ischemic phase of the organ preservation period. The donor liver is kept warm and perfused all through the process of procurement from the donor body, preservation outside the body, and during the implant into the recipient up until the moment of reperfusion with the recipient’s blood. The technique clearly improved early transplant function. The reduction in non-anastomotic strictures was largely asymptomatic, so it remains to be seen if this technique can significantly reduce the risk of symptomatic strictures in higher risk livers.
Aims:
To compare outcomes in the novel technique of ischaemia-free liver transplantation (IFLT) to conventional liver transplantation (CLT).
Interventions:
The technique being tested is IFLT compared with CLT. IFLT is a complex technique in which during DBD donation the perfusion cannulas of a Liver Assist can be placed in the donor liver prior to cessation of donor circulation. The arterial canula placed via the splenic artery, portal vein via and vein graft and the outflow canula into the infra-hepatic cava. The perfusion can then seamlessly be transferred from donor circulation to NMP, the liver is then procured and continued NMP until implantation. The supra-hepatic caval (piggyback), portal vein and hepatic arterial anastomoses are then performed in the recipient while NMP continues, and once completed the NMP cannulas are removed, and hepatic perfusion transferred from NMP to recipient without interruption of perfusion.
Participants:
65 adult whole liver-only transplant recipients.
Outcomes:
The primary endpoint was early allograft dysfunction (EAD) within 7 days as defined by the Olthoff criteria. The secondary endpoints included primary non-function, post-reperfusion syndrome, biliary complications, post-reperfusion lactate, post-transplant LFTs, patient and graft survival at 1,6, & 12 months, ITU stay and overall hospital stay.
Follow Up:
12 months
BACKGROUND & AIMS:
Ischemia-reperfusion injury (IRI) has thus far been considered as an inevitable component of organ transplantation, compromising outcomes, and limiting organ availability. Ischemia-free organ transplantation is a novel approach designed to avoid IRI, with the potential to improve outcomes.
METHODS:
In this randomized-controlled clinical trial, recipients of livers from donors after brain death were randomly assigned to receive either an ischemia-free or a 'conventional' transplant. The primary endpoint was the incidence of early allograft dysfunction. Secondary endpoints included complications related to graft IRI.
RESULTS:
Out of 68 randomized patients, 65 underwent transplants and were included in the analysis. 32 patients received ischemia-free liver transplantation (IFLT), and 33 received conventional liver transplantation (CLT). Early allograft dysfunction occurred in two recipients (6%) randomized to IFLT and in eight (24%) randomized to CLT (difference -18%; 95% CI -35% to -1%; p = 0.044). Post-reperfusion syndrome occurred in three recipients (9%) randomized to IFLT and in 21 (64%) randomized to CLT (difference -54%; 95% CI -74% to -35%; p <0.001). Non-anastomotic biliary strictures diagnosed with protocol magnetic resonance cholangiopancreatography at 12 months were observed in two recipients (8%) randomized to IFLT and in nine (36%) randomized to CLT (difference, -28%; 95% CI -50% to -7%; p = 0.014). The comprehensive complication index at 1 year after transplantation was 30.48 (95% CI 23.25-37.71) in the IFLT group vs. 42.14 (95% CI 35.01-49.26) in the CLT group (difference -11.66; 95% CI -21.81 to -1.51; p = 0.025).
CONCLUSIONS:
Among patients with end-stage liver disease, IFLT significantly reduced complications related to IRI compared to a conventional approach.
CLINICAL TRIAL REGISTRATION:
chictr.org. ChiCTR1900021158.
IMPACT AND IMPLICATIONS:
Ischemia-reperfusion injury has thus far been considered as an inevitable event in organ transplantation, compromising outcomes and limiting organ availability. Ischemia-free liver transplantation is a novel approach of transplanting donor livers without interruption of blood supply. We showed that in patients with end-stage liver disease, ischemia-free liver transplantation, compared with a conventional approach, led to reduced complications related to ischemia-reperfusion injury in this randomized trial. This new approach is expected to change the current practice in organ transplantation, improving transplant outcomes, increasing organ utilization, while providing a clinical model to delineate the impact of organ injury on alloimmunity.
Mr John O'Callaghan, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This paper reports on a biomarker study conducted alongside the Consortium for Organ Preservation in Europe (COPE) study that compared Oxygenated HMP with standard HMP prior to kidney transplantation. The clinical results have been published previously (Jochmans et al 2020). Flavin Mononucleotide (FMN) is a cofactor for the mitochondrial membrane complex-I, which dissociates from the complex following ischaemia-reperfusion injury. It was therefore speculated that release of FMN in the perfusate whilst on machine perfusion may be an indicator for ischaemic injury, with some evidence in liver transplantation that correlates with poor lactate clearance and early graft loss. Analysis was done by fluorescence spectroscopy and liquid chromatography mass spectrometry. The primary analysis was to correlate FMN levels in machine perfusate immediately prior to transplantation with early and late post-transplant outcomes. Fluorescence in the FMN region was found to significantly increase during the preservation period in kidneys preserved with both oxygenated and standard HMP. As these profiles were similar, results from both groups were combined for the further analysis to increase sensitivity. Despite this approach, FMN was not found to be a clinically relevant biomarker to predict early or late graft function. The authors conducted a validation process, which suggested that the increase in fluorescence during perfusion may not be specifically related to FMN and therefore it may not be reliable perfusate biomarker in kidney transplantation.
Aims:
This study aimed to investigate the ability of flavin mononucleotide (FMN) to predict the quality of kidney grafts during hypothermic machine perfusion (HMP) with oxygenation (HMPO2).
Interventions:
Kidneys were randomised to receive either HMPO2 or HMP.
Participants:
197 kidney pairs (n=394) were randomised, out of which 220 were transplanted.
Outcomes:
The primary outcome was the association between end of perfusion (P3) and early transplant outcomes (immediate graft function, DGF, primary non-function (PNF) and serum creatinine (SCr)) and late post-transplant outcomes (estimated creatinine clearance, graft failure and biopsy proven rejection). The secondary outcomes were associations for the P1 and P2 timepoints (beginning and during perfusion) and the delta perfusion (ΔP) with early and late posttransplant outcomes.
Follow Up:
12 months posttransplantation.
Hypothermic machine perfusion (HMP) provides preservation superior to cold storage and may allow for organ assessment prior to transplantation. Since flavin mononucleotide (FMN) in perfusate has been proposed as a biomarker of organ quality during HMP of donor livers, the aim of this study was to validate FMN as a biomarker for organ quality in the context of HMP preserved kidneys. Perfusate samples (n = 422) from the paired randomised controlled COPE-COMPARE-trial, comparing HMP with oxygenation (HMPO2) versus standard HMP in kidneys, were used. Fluorescence intensity (FI) was assessed using fluorescence spectroscopy (excitation 450nm; emission 500-600nm) and validated by fluorospectrophotometer and targeted liquid chromatography mass spectrometry (LC-MS/MS). Fluorescence intensity (FI)(ex450;em500-600) increased over time during machine perfusion in both groups (p<0.0001). This increase was similar for both groups (p = 0.83). No correlation, however, was found between FI(ex450;em500-600) and post-transplant outcomes, including day 5 or 7 serum creatinine (p = 0.11; p = 0.16), immediate graft function (p = 0.91), creatinine clearance and biopsy-proven rejection at one year (p = 0.14; p = 0.59). LC-MS/MS validation experiments of samples detected FMN in only one perfusate sample, whilst the majority of samples with the highest fluorescence (n = 37/38, 97.4%) remained negative. In the context of clinical kidney HMP, fluorescence spectroscopy unfortunately appears to be not specific and probably unsuitable for FMN. This study shows that FMN does not classify as a clinically relevant predictive biomarker of kidney graft function after transplantation.
Mr Simon Knight, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This multicentre study randomised patients on the heart transplant waiting list to waiting for a standard, DBD organ; or to a DCD organ (assessed via ex-vivo perfusion) or DBD organ, whichever came first. 297 wait-listed patients were randomised, of whom 180 were transplanted in the study – 90 with DBD organs, and 90 with DCD organs. At 6 months post-transplant, there was no difference in risk-adjusted survival or other clinical outcomes between the two groups. This is a very well-designed study. Studies that alter with organ allocation are challenging as they must not disadvantage patients by reducing the chances of an organ offer. By allowing patients in the DCD arm to receive a DBD organ if allocated, the investigators overcome this. At least in the short term, outcomes from DCD hearts assessed ex-vivo appear equivalent, and have the potential to increase the rate of transplantation – within the study, 67% patients randomised to the DCD cohort were transplanted compared to 39% in the DBD cohort.
Aims:
The aim of this study was to investigate posttransplant outcomes of hearts obtained from donation after circulatory death (DCD) versus donation after brain death (DBD) donors.
Interventions:
Participants were randomised to receive a heart from either a DCD or DBD donor.
Participants:
297 adult candidates for heart transplantation were randomised, out of which 180 underwent transplantation.
Outcomes:
The primary efficacy outcome was patient survival adjusted for prespecified donor and recipient risk factors. The secondary efficacy outcome was the donor-heart utilization rate.
Follow Up:
1 year posttransplantation
BACKGROUND:
Data showing the efficacy and safety of the transplantation of hearts obtained from donors after circulatory death as compared with hearts obtained from donors after brain death are limited.
METHODS:
We conducted a randomized, noninferiority trial in which adult candidates for heart transplantation were assigned in a 3:1 ratio to receive a heart after the circulatory death of the donor or a heart from a donor after brain death if that heart was available first (circulatory-death group) or to receive only a heart that had been preserved with the use of traditional cold storage after the brain death of the donor (brain-death group). The primary end point was the risk-adjusted survival at 6 months in the as-treated circulatory-death group as compared with the brain-death group. The primary safety end point was serious adverse events associated with the heart graft at 30 days after transplantation.
RESULTS:
A total of 180 patients underwent transplantation; 90 (assigned to the circulatory-death group) received a heart donated after circulatory death and 90 (regardless of group assignment) received a heart donated after brain death. A total of 166 transplant recipients were included in the as-treated primary analysis (80 who received a heart from a circulatory-death donor and 86 who received a heart from a brain-death donor). The risk-adjusted 6-month survival in the as-treated population was 94% (95% confidence interval [CI], 88 to 99) among recipients of a heart from a circulatory-death donor, as compared with 90% (95% CI, 84 to 97) among recipients of a heart from a brain-death donor (least-squares mean difference, -3 percentage points; 90% CI, -10 to 3; P<0.001 for noninferiority [margin, 20 percentage points]). There were no substantial between-group differences in the mean per-patient number of serious adverse events associated with the heart graft at 30 days after transplantation.
CONCLUSIONS:
In this trial, risk-adjusted survival at 6 months after transplantation with a donor heart that had been reanimated and assessed with the use of extracorporeal nonischemic perfusion after circulatory death was not inferior to that after standard-care transplantation with a donor heart that had been preserved with the use of cold storage after brain death. (Funded by TransMedics; ClinicalTrials.gov number, NCT03831048.).
Mr John O'Callaghan, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This paper documents in detail the study protocol for a trial of end-ischaemic hypothermic oxygenated machine perfusion (HOPE) in extended criteria donor livers. There is a pragmatic element to the design, as livers will be preserved by static cold storage and then in the study group will receive 1-4 hours of HOPE. By concentrating on ECD livers, the study is more likely to find a significant impact on the primary outcome of early allograft dysfunction. The study is powered (80%) for a reduction in early allograft dysfunction from 30% to 15%, accounting for 10% dropout rate. Randomization will occur after allocation of the liver graft to a recipient. Allocation concealment is maintained, but there is no blinding of the surgical team nor patient. Data analysts will be blinded to group allocation. Interestingly the trial commenced in 2019 and is ongoing. This paper is published in order to “prevent biased analysis of trial outcomes and improve transparency of the trial results”. The study is funded by the French Ministry of Health and is being conducted at 8 transplant centres in France.
Aims:
This is a protocol for a randomised controlled trial that aims to determine the efficacy of hypothermic oxygenated machine perfusion (HOPE) when used prior to transplantation of extended criteria donor (ECD) liver grafts obtained from brain-dead donors, for reduction of early allograft dysfunction (EAD) post-operation in comparison to simple cold static storage.
Interventions:
ECD liver grafts will be randomly assigned to receive either HOPE or static cold storage.
Participants:
Adult patients (≥ 18 years) transplanted with a liver graft harvested from a brain-dead ECD.
Outcomes:
The primary outcomes are early allograft dysfunction (EAD) and primary non-function (PNF). The secondary outcomes include quality of conservation; ischemia–reperfusion injuries, intra-operative events; 90-day morbidity and mortality; duration of intermediate care unit stay and total hospital stay; actuarial graft and patient’s survival rates; and costs of liver transplantation with ECD grafts using HOPE or not and incremental cost-effectiveness ratio.
Follow Up:
12 months (± 30 days) following transplantation (36 months maximum).
BACKGROUND:
Given the scarce donor supply, an increasing number of so-called marginal or extended criteria donor (ECD) organs are used for liver transplantation. These ECD liver grafts are however known to be associated with a higher rate of early allograft dysfunction and primary non-function because of a greater vulnerability to ischemia-reperfusion injury. The end-ischemic hypothermic oxygenated machine perfusion (HOPE) technique may improve outcomes of liver transplantation with ECD grafts by decreasing reperfusion injury.
METHODS:
HOPExt trial is a comparative open-label, multicenter, national, prospective, randomized, controlled study, in two parallel groups, using static cold storage, the gold standard procedure, as control. The trial will enroll adult patients on the transplant waiting list for liver failure or liver cirrhosis and/or liver malignancy requiring liver transplantation and receiving an ECD liver graft from a brain-dead donor. In the experimental group, ECD liver grafts will first undergo a classical static cold (4 °C) storage followed by a hypothermic oxygenated perfusion (HOPE) for a period of 1 to 4 h. The control group will consist of the classic static cold storage which is the gold standard procedure in liver transplantation. The primary objective of this trial is to study the efficacy of HOPE used before transplantation of ECD liver grafts from brain-dead donors in reducing postoperative early allograft dysfunction within the first 7 postoperative days compared to simple cold static storage.
DISCUSSION:
We present in this protocol all study procedures in regard to the achievement of the HOPExt trial, to prevent biased analysis of trial outcomes and improve the transparency of the trial results. Enrollment of patients in the HOPExt trial has started on September 10, 2019, and is ongoing.
TRIAL REGISTRATION:
ClinicalTrials.gov NCT03929523. Registered on April 29, 2019, before the start of inclusion.
Mr Simon Knight, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
This multicentre study randomised kidneys from controlled DCD donors to static cold storage (SCS) or to normothermic machine perfusion (NMP) with oxygenated blood for one hour prior to transplant. 338 kidneys were randomised. Primary endpoint was delayed graft function (DGF), defined by requirement for dialysis during the first 7 days post-transplant. Although NMP was feasible and safe, no difference in clinical endpoints were seen. The study is well-designed and reported and would appear to confirm that a short period of NMP prior to transplant does not confer clinical benefit. It is worth noting that the choice of primary endpoint can lead to challenges, as patients that are transplanted pre-emptively are less likely to reach the primary endpoint (DGF determined by dialysis need). As there was an imbalance between the proportions of pre-emptive patients in the control arm and study arm (22% versus 11%) this may impact the results. However, all secondary measures of graft function including functional DGF, DGF duration and creatinine reduction ratio were equivalent between the arms.
Aims:
The aim of this study was to compare the posttransplant outcomes of conventional static cold storage (SCS) alone or SCS combined with 1 hour of normothermic machine perfusion (NMP) in donation after circulatory death (DCD) kidney transplant patients.
Interventions:
Participants were randomised to either SCS plus 1-hour NMP or SCS alone.
Participants:
338 adult (≥18 years) kidney transplant patients that received a kidney from adult (≥ 18 years) DCD donors.
Outcomes:
The primary endpoint was delayed graft function (DGF). The secondary endpoints included the incidence of primary nonfunction (PNF), duration of DGF, functional DGF, duration of hospital stay, estimated glomerular filtration rate (eGFR) or serum creatinine, and patient and allograft survival.
Follow Up:
12 months posttransplantation.
Kidney transplantation is the optimal treatment for end-stage renal disease, but it is still severely limited by a lack of suitable organ donors. Kidneys from donation after circulatory death (DCD) donors have been used to increase transplant rates, but these organs are susceptible to cold ischemic injury in the storage period before transplantation, the clinical consequence of which is high rates of delayed graft function (DGF). Normothermic machine perfusion (NMP) is an emerging technique that circulates a warmed, oxygenated red-cell-based perfusate through the kidney to maintain near-physiological conditions. We conducted a randomized controlled trial to compare the outcome of DCD kidney transplants after conventional static cold storage (SCS) alone or SCS plus 1-h NMP. A total of 338 kidneys were randomly allocated to SCS (n = 168) or NMP (n = 170), and 277 kidneys were included in the final intention-to-treat analysis. The primary endpoint was DGF, defined as the requirement for dialysis in the first 7 d after transplant. The rate of DGF was 82 of 135 (60.7%) in NMP kidneys versus 83 of 142 (58.5%) in SCS kidneys (adjusted odds ratio (95% confidence interval) 1.13 (0.69-1.84); P = 0.624). NMP was not associated with any increase in transplant thrombosis, infectious complications or any other adverse events. A 1-h period of NMP at the end of SCS did not reduce the rate of DGF in DCD kidneys. NMP was demonstrated to be feasible, safe and suitable for clinical application. Trial registration number: ISRCTN15821205 .
Mr Keno Mentor, Centre for Evidence in Transplantation, Nuffield Department of Surgical Sciences University of Oxford
Conclusion:
Hypothermic oxygenated perfusion (HOPE) liver perfusion has shown promising results in preclinical studies but has yet to demonstrate consistent benefit for clinically relevant endpoints. This multicentre RCT compared the complication rate following DBD liver transplant (LT) between conventional cold storage versus treatment with HOPE prior to implantation. The study showed no significant difference in the rate of Clavien score > 3 between the two groups. A post hoc analysis compared the rate of liver-related graft loss, but the rationale for this analysis is not clear and the difference reported was not statistically significant. This study thus did not demonstrate any benefit to utilising HOPE in DBD liver transplantation.
Aims:
This study aimed to investigate the role of hypothermic oxygenated perfusion (HOPE) on morbidity within 1 year following liver transplantation.
Interventions:
Livers were randomised to either conventionally cold stored (control group), or cold stored followed by 1-2 hours HOPE treatment before implantation (HOPE group).
Participants:
Patients listed for liver only transplantation (18 years of age).
Outcomes:
The primary outcome was the occurrence of one or more major post-transplant complication. Secondary outcomes were comprehensive complication index (CCI), graft survival, patient survival, laboratory parameters, duration of hospital and intensive care unit stay, and biliary complications.
Follow Up:
12 months
BACKGROUND & AIMS:
Machine perfusion is a novel method intended to optimize livers before transplantation. However, its effect on morbidity within a 1-year period after transplantation has remained unclear.
METHODS:
In this multicenter controlled trial, we randomly assigned livers donated after brain death (DBD) for liver transplantation (LT). Livers were either conventionally cold stored (control group), or cold stored and subsequently treated by 1-2 h hypothermic oxygenated perfusion (HOPE) before implantation (HOPE group). The primary endpoint was the occurrence of at least one post-transplant complication per patient, graded by the Clavien score of ≥III, within 1-year after LT. The comprehensive complication index (CCI), laboratory parameters, as well as duration of hospital and intensive care unit stay, graft survival, patient survival, and biliary complications served as secondary endpoints.
RESULTS:
Between April 2015 and August 2019, we randomized 177 livers, resulting in 170 liver transplantations (85 in the HOPE group and 85 in the control group). The number of patients with at least one Clavien ≥III complication was 46/85 (54.1%) in the control group and 44/85 (51.8%) in the HOPE group (odds ratio 0.91; 95% CI 0.50-1.66; p = 0.76). Secondary endpoints were also not significantly different between groups. A post hoc analysis revealed that liver-related Clavien ≥IIIb complications occurred less frequently in the HOPE group compared to the control group (risk ratio 0.26; 95% CI 0.07-0.77; p = 0.027). Likewise, graft failure due to liver-related complications did not occur in the HOPE group, but occurred in 7% (6 of 85) of the control group (log-rank test, p = 0.004, Gray test, p = 0.015).
CONCLUSIONS:
HOPE after cold storage of DBD livers resulted in similar proportions of patients with at least one Clavien ≥III complication compared to controls. Exploratory findings suggest that HOPE decreases the risk of severe liver graft-related events.
IMPACT AND IMPLICATIONS:
This randomized controlled phase III trial is the first to investigate the impact of hypothermic oxygenated perfusion (HOPE) on cumulative complications within a 12-month period after liver transplantation. Compared to conventional cold storage, HOPE did not have a significant effect on the number of patients with at least one Clavien ≥III complication. However, we believe that HOPE may have a beneficial effect on the quantity of complications per patient, based on its application leading to fewer severe liver graft-related complications, and to a lower risk of liver-related graft loss. The HOPE approach can be applied easily after organ transport during recipient hepatectomy. This appears fundamental for wide acceptance since concurring perfusion technologies need either perfusion at donor sites or continuous perfusion during organ transport, which are much costlier and more laborious. We conclude therefore that the post hoc findings of this trial should be further validated in future studies.
CET Conclusion