Conversion to sirolimus immunosuppression in liver transplantation recipients with hepatocellular carcinoma: Report of an initial experience

Liver transplantation for isolated unresectable colorectal liver metastases - Protocol for a service evaluation in the United Kingdom - UKCoMET study

BACKGROUND

Liver transplantation (LT) for unresectable colorectal liver metastases (CRCLM) demonstrates good overall survival for selected patients in contemporary studies, with 5-year survival of 80%. A Fixed Term Working Group (FTWG), set up by NHS Blood and Transplant (NHSBT) Liver Advisory Group (LAG), advised whether CRCLM should be considered for LT in United Kingdom. Their recommendation was that LT may be undertaken for isolated and unresectable CRCLM using strict selection criteria as a national clinical service evaluation.

METHODS

Opinions were sought from colorectal cancer/LT patient representatives, experts in colorectal cancer surgery/oncology, LT surgery, hepatology, hepatobiliary radiology, pathology, and nuclear medicine, and appropriate patient selection criteria, referral and transplant listing pathways were identified.

RESULTS

This paper summarises selection criteria for LT in United Kingdom for isolated and unresectable CRCLM patients, and highlights referral framework and pre-transplant assessment criteria. Finally, oncology-specific outcome measures to be utilised for assessing applicability of LT are described.

CONCLUSION

This service evaluation represents a significant development for colorectal cancer patients in United Kingdom and a meaningful step forward in the field of transplant oncology. This paper details the protocol for the pilot study, scheduled to begin in the fourth quarter of 2022 in United Kingdom.

A mixed blessing for liver transplantation patients - Rapamycin

BACKGROUND

Liver transplantation (LT) is an effective treatment option for end-stage liver disease. Mammalian target of rapamycin (mTOR) inhibitors, such as rapamycin, are widely used post LT.

DATA SOURCES

In this review, we focused on the anti-cancer activities and metabolic side effects of rapamycin after LT. The literature available on PubMed for the period of January 1999-September 2022 was reviewed. The key words were rapamycin, sirolimus, liver transplantation, hepatocellular carcinoma, diabetes, and lipid metabolism disorder.

RESULTS

Rapamycin has shown excellent effects and is safer than other immunosuppressive regimens. It has exhibited excellent anti-cancer activity and has the potential in preventing hepatocellular carcinoma (HCC) recurrence post LT. Rapamycin is closely related to two long-term complications after LT, diabetes and lipid metabolism disorders.

CONCLUSIONS

Rapamycin prevents HCC recurrence post LT in some patients, but it also induces metabolic disorders. Reasonable use of rapamycin benefits the liver recipients.

Achieving tolerance modifies cancer susceptibility profiles in liver transplant recipients

Long-term survival of transplant recipients is significantly impacted by malignancy. We aimed to determine whether calcineurin inhibitor (CNI)-treated recipients converted to and weaned off molecular target of rapamycin inhibitor (mTOR-I) therapy have favorable changes in their molecular profiles in regard to malignancy risk. We performed gene expression profiling from liver biopsy and blood (PBMC) specimens followed by network analysis of key dysregulated genes, associated diseases and disorders, molecular and cellular functions using IPA software. Twenty non-immune, non-viremic patients were included, and 8 of them achieved tolerance. Two comparisons were performed: (1) tolerance time point vs tacrolimus monotherapy and (2) tolerance time point vs sirolimus monotherapy. Upon achieving tolerance, IPA predicted significant activation of DNA damage response (p = 5.40e-04) and inhibition of DNA replication (p = 7.56e-03). Conversion from sirolimus to tolerance showed decrease in HCC (p = 1.30e-02), hepatic steatosis (p = 5.60e-02) and liver fibrosis (p = 2.91e-02) associated genes. In conclusion, this longitudinal study of patients eventually achieving tolerance reveals an evolving molecular profile associated with decreased cancer risk and improved hepatic steatosis and liver fibrosis. This provides a biological rationale for attempting conversion to mTOR-I therapy and tolerance following liver transplantation particularly in patients at higher risk of cancer incidence and progression post-transplant.

Efficacy and safety of lenvatinib for preventing tumor recurrence after liver transplantation in hepatocellular carcinoma beyond the Milan criteria

Background

Lenvatinib is one of the first-line treatments for unresectable hepatocellular carcinoma (HCC). However, data are lacking on lenvatinib in the postoperative setting.

Methods

This retrospective analysis enrolled 242 patients with HCC who underwent liver transplantation (LTx). Eligible patients were divided into 2 groups according to their use of adjuvant lenvatinib following LTx (lenvatinib, n=42; control, n=200). The primary outcome measures were overall survival (OS), time to recurrence (TTR), and safety. Kaplan-Meier analysis was applied to calculate the OS, while a competing risk model was used to estimate the cumulative incidence of recurrence.

Results

The lenvatinib group showed more advanced tumors and a higher proportion of HCC beyond the Milan criteria (P<0.001) than the control group. There were no significant differences in both the OS and TTR between the 2 groups. After focusing on the patients with HCC beyond the Milan criteria, baseline characteristics were similar in the lenvatinib group (n=38) and the control group (n=102). Competing risk analysis showed lenvatinib significantly prolonged TTR after LTx versus the control group [sub-hazard ratio (sHR), 0.40; 95% confidence interval (CI): 0.17 to 0.93; P=0.031]. In the multivariate competing risk model, adjuvant lenvatinib was an independent protective factor for tumor recurrence after LTx in patients with HCC beyond the Milan criteria (sHR, 0.33; 95% CI: 0.13 to 0.83; P=0.018). The rate of early recurrence within t2 years after LTx was also significantly decreased in the lenvatinib group (15.8% vs. 33.3%, P=0.041). However, the lenvatinib group exhibited comparable OS with the control group in patients with HCC beyond the Milan criteria. Treatment-related adverse events (TRAEs) and Grade ≥3 TRAEs occurred in 40 (95.2%) and 13 (31%) patients who received adjuvant lenvatinib, respectively. No treatment-related death was reported.

Conclusions

Postoperative lenvatinib administration may provide clinical benefits and is well tolerated in patients with HCC beyond the Milan criteria who undergo LTx.

Detection of circulating tumour cells enables early recurrence prediction in hepatocellular carcinoma patients undergoing liver transplantation

BACKGROUND & AIMS

Liver transplantation (LTx) is one of the most effective treatments for hepatocellular carcinoma (HCC); however, tumour recurrence after LTx often leads to poor outcomes. This study investigated the value of circulating tumour cells (CTCs) as a predictor of recurrence following LTx in patients with HCC.

METHODS

This analysis included 193 patients with HCC who underwent LTx at our institute and accepted pre- and post-operative CTC detection; 38 were selected for serial CTC monitoring. The predictive value of CTCs for tumour recurrence in patients with HCC following LTx was evaluated. Single-cell whole genome sequencing was used to characterize CTCs.

RESULTS

Overall, the CTC burden decreased after LTx (P < .05). Post-operative CTC count ≥ 1 per 5 mL peripheral blood was identified as a potential biomarker for predicting tumour recurrence after LTx, especially in patients with no detectable CTCs prior to LTx and negative tumour serological biomarkers. The predictive value of post-operative CTC count ≥ 1 per 5 mL blood was retained in patients who did not meet the Milan criteria, University of California San Francisco (UCSF) criteria, or Fudan criteria (all P < .05). Furthermore, post-operative serial CTC detection may be useful in post-surgical surveillance for HCC recurrence.

CONCLUSIONS

CTCs may be a useful biomarker to evaluate recurrence risk following LTx in patients with HCC. Evaluation based on CTC detection may enhance the post-transplant management of HCC, and improve the therapeutic efficacy of LTx.

Sirolimus and mTOR Inhibitors: A Review of Side Effects and Specific Management in Solid Organ Transplantation

Inhibitors of mechanistic target of rapamycin (mTOR inhibitors) are used as antiproliferative immunosuppressive drugs and have many clinical applications in various drug combinations. Experience in transplantation studies has been gained regarding the side effect profile of these drugs and the potential benefits and limitations compared with other immunosuppressive agents. This article reviews the adverse effects of mTOR inhibitors in solid organ transplantation, with special attention given to mechanisms hypothesized to cause adverse events and their management strategies.

Treatment with mTOR inhibitors after liver transplantation enables a sustained increase in regulatory T-cells while preserving their suppressive capacity

BACKGROUND

The mammalian targets of rapamycin (mTOR) inhibitors (sirolimus [SRL] and everolimus [EVR]) are used after transplantation for their immunosuppressive activity. Regulatory T-cells (Tregs) play a crucial role in immune tolerance. mTOR inhibitors appear to preserve Tregs, unlike Tacrolimus (Tac).

AIM

The aim of this study was to evaluate the number and function of Tregs in liver transplant recipients before and after conversion from Tac to mTOR inhibitors.

METHODS

Fifteen patients with stable graft function where converted to SRL (n=5) or EVR (n=10). Tregs (CD4⁺ CD25⁺ FoxP3⁺ CD127^low) number and activity were analysed prospectively in blood cells using flow cytometry, and functional assay.

RESULTS

Patients of both groups displayed a sustained rise in Treg levels after introduction of mTOR inhibitors (Treg levels at 3 months: 6.45±0.38% of CD4 T-cells, vs. baseline level of 3.61±0.37%, P<0.001; mean fold increase 2.04±0.73). In SRL group, 3-month Treg levels were 6.01±0.53 vs. 3.79±0.39; P=0.037, while in EVR group they were 6.63±0.67 vs. 3.54±0.51; P=0.001. By contrast, no statistical change was observed in an unconverted Tac control group. Tregs also preserved their functional ability to suppress activated T-cells.

CONCLUSION

These results suggest that mTOR inhibitors induce a significant increase in Tregs while maintaining suppressive activity after LT.

Investigating Effect of Rapamycin and Metformin on Angiogenesis in Hepatocellular Carcinoma Cell Line

Purpose: Human hepatocellular carcinoma is one of the most common causes of death in the world. Metformin and rapamycin may decrease the expression of VEGF protein and subsequently angiogenesis. The purpose of this study was to evaluate the effect of these two drugs on expression of VEGF protein and the cell proliferation in the hepatocellular carcinoma cell line (ATCC HB-8065).

Methods: HepG2 was cultured in RPMI-1640 medium at 37°C for 48h as a pre-culture and then treated by different concentrations of metformin (0, 5, 10 and 20 mM) and rapamycin (0, 5, 10 and 20 nM) at different times (12, 24 and 48 h). Cell viability was assessed by the MTT assay. Total RNA was extracted by the Trizol reagent and VEGF gene expression was analyzed by quantitative real-time PCR and was calculated by 2^–ΔCt method. The VEGF protein level was determined by Elisa assay. Finally, Apoptosis index was calculated by DAPI staining.

Results: Metformin and rapamycin significantly decrease cancer cells viability (p<0.05). Rapamycin but not metformin decreases VEGF gene expression in HepG2 cells. Metformin and rapamycin significantly induce cell apoptosis in hepatocellular carcinoma (HCC) cells.

Conclusion: Metformin and rapamycin have an anti-tumor effect on HCC. According to our data rapamycin might have an anti-angiogenesis effect via inhibition of VEGF expression. Our results provide an insight into future clinical strategies to improve chemotherapy outcomes in HCC.

Hepatocellular cancer and recurrence after liver transplantation: what about the impact of immunosuppression?

Liver transplantation (LT) has originally been designed to treat hepatobiliary malignancies. The initial results of LT for hepatocellular cancer (HCC) were, however, dismal this mainly due to the poor patient selection procedure. Better surgical and perioperative care and, especially, the refinement of selection criteria led to a major improvement of results, making HCC nowadays (again!) one of the leading indications for LT. This evolution is clearly shown by the innumerable reports aiming to further extend inclusion criteria for LT in HCC patients. Nonetheless, the vast majority of papers only deals with morphologic (tumour diameter and number) and (only recently) biologic (tumour markers and response to locoregional treatment) parameters to do so. Curiously enough, the role of both the immune competent state of the recipient as well as the impact of both immunosuppression (IS) type and load has been very poorly addressed in this context, even if it has been shown for a long time, based on both basic and clinical research, that they all play a key role in the outcome of any oncologic treatment and in the development of de novo as well as recurrent tumours. This chapter aims to give, after a short introductive note about the currently used inclusion criteria of HCC patients for LT and about the role of IS in carcinogenesis, a comprehensive overview of the actual literature related to the impact of different immunosuppressive drugs and schemes on outcome of LT in HCC recipients. Unfortunately, up to now solid conclusions cannot be drawn due to the lack of high-level evidence studies caused by the heterogeneity of the studied patient cohorts and the lack of prospectively designed and randomized studies. Based on long-term personal experience with immunosuppressive handling in LT some proposals for further clinical research and practice are put forward. The strategy of curtailing and minimising IS should be explored in the growing field of transplant oncology taking thereby into account the immunological privilege of the liver allograft. These strategies will become more and more compelling when further extending the indications in which adjuvant chemotherapy will probably become an inherent part of the therapeutic scheme of HCC liver recipients.

Sirolimus Use in Liver Transplant Recipients With Hepatocellular Carcinoma: A Randomized, Multicenter, Open-Label Phase 3 Trial

We investigated whether sirolimus-based immunosuppression improves outcomes in liver transplantation (LTx) candidates with hepatocellular carcinoma (HCC).

In a large prospective randomized open-label international trial, liver transplant recipients for HCC were randomized to receive non-mTOR-inhibitor-based-treatment or mTOR-inhibitor-based-treatment. Results indicate overall sirolimus does not improve long-term recurrence-free survival beyond 5 years while a benefit was seen in low-risk patients. Supplemental digital content is available in the text.

Everolimus-based immunosuppression in patients with hepatocellular carcinoma at high risk of recurrence after liver transplantation: a case series

BACKGROUND

Liver transplantation offers the most effective treatment in patients with hepatocellular carcinoma (HCC). However, transplant patients outside the Milan criteria have a high risk of tumor recurrence, which has been linked to standard immunosuppression regimens. Everolimus is a mammalian target of rapamycin inhibitor that has been used for immunosuppression, but its effect on recurrence and survival in HCC patients with a high risk of tumor recurrence has not been examined. We compared long-term survival and cumulative recurrence in high-risk patients receiving everolimus-based immunosuppression after liver transplantation for HCC with an historic control group.

METHODS

The everolimus group comprised 21 patients receiving a liver transplant at our center from February 2005 to December 2010. The control group comprised 31 patients receiving a liver transplant from May 1994 to January 2005. All patients received cyclosporine or tacrolimus as initial post-transplant immunosuppression. Patients in the everolimus group switched to everolimus 2 weeks later.

RESULTS

There were no differences between the two groups in number of rejection episodes or of infectious or surgical complications. Five-year survival was 60.2% in the everolimus group and 32.3% in the control group (P = .05). Five-year cumulative recurrence rate was 61.3% in the control group and 41.3% in the everolimus group. Treatment with everolimus was identified as an independent predictor of longer survival (hazard ratio = 0.34; P = .02).

CONCLUSIONS

Patients receiving liver transplantation for HCC with a high risk of tumor recurrence may well benefit from everolimus-based immunosuppression, with no added risks of rejection or other post-transplant complications.

Liver transplantation for advanced hepatocellular carcinoma: how far can we go?

Liver transplantation is one of the most effective treatment options for hepatocellular carcinoma. Although the Milan criteria have been widely used to identify suitable candidates for liver transplant with a good prognosis, many transplant centers have developed and actually used more expanded criteria. Living donor liver transplant (LDLT) is at the center of expansion of criteria because it is based on the personal relationship between a recipient and a donor. Asian LDLT centers have developed various expanded criteria for LDLT using tumor biologic markers as well as the size and number of the tumors. However, there is no consensus on the limit of the expansion of criteria. Here, we present our experience and opinion on LDLT for advanced hepatocellular carcinoma.

Comparison of steroid-free immunosuppression and standard immunosuppression for liver transplant patients with hepatocellular carcinoma

Immunosuppression therapy following liver transplantation often includes steroids. However, extended corticosteroid therapy is associated with numerous complications. This study evaluated the efficacy and safety of using basiliximab in place of a corticosteroid for immunosuppression following liver transplantation for hepatocellular carcinoma (HCC) in Chinese patients. The records of 178 patients with HCC who underwent orthotopic liver transplantation from January 2003 to December 2009 were retrospectively reviewed. All patients received immunosuppression therapy that contained either basiliximab (n = 78) or steroids (n = 100) in addition to tacrolimus and mycophenolate mofetil. Assessments included complications related to liver transplantation, occurrence of steroid side effects, recurrence of HCC, and patient and graft survival. A smaller proportion of patients receiving basiliximab compared with steroids experienced de novo diabetes (38.7% vs. 91.0%, respectively) or long-term de novo diabetes mellitus (7.7% vs. 38.0%, respectively) (both, P<0.0001). The median overall and disease free survival was similar between basiliximab (50.8 months and 19.6 months, respectively) and steroid treated patients (64.2 months and 23.8 months, respectively). The 5-year overall survival and disease free survival rates was also similar between the basiliximab (42.5% and 38.9%, respectively) and steroid (50.5% and 39.2%) groups (all, P>0.730). However, in patients who met the Milan criteria basiliximab was associated with greater 5-year overall survival rate as compared with steroid therapy (88.9% vs. 57.4%, respectively, P = 0.022). These findings provide further evidence of the negative impact of steroids as a part of immunosuppression therapy following liver transplantation for HCC.

Meta-analysis: recurrence and survival following the use of sirolimus in liver transplantation for hepatocellular carcinoma

BACKGROUND

The use of sirolimus (SRL)-based immunosuppression protocols have been reported to reduce recurrence rates following liver transplantation (LT) for hepatocellular carcinoma (HCC), although this is still a matter for debate.

AIM

To undertake a systematic review and meta-analysis of available literature on the usage of SRL as an immunosuppressive agent following LT for HCC, with a view to comparing cancer outcomes with the commonly used calcineurin inhibitors (CNIs).

METHODS

Systematic review and meta-analysis carried out in line with the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Primary outcomes of interest were tumour recurrence rate and recurrence-free survival (RFS). Secondary outcomes were recurrence-related mortality and overall survival (OS).

RESULTS

In all, 5 studies met the inclusion criteria (n = 474). The recurrence rate was lower in SRL group (4.9-12.9%) in comparison with CNIs (17.3-38.7%). The 1-, 3- and 5-year RFS was 93-96%, 82-86% and 79-80% for SRL group, which was much better in comparison with the CNIs 70-78%, 64-65% and 54-60% respectively. Similarly, 1-, 3- and 5-year OS was much better for SRL group (94-95%, 85% and 80%) in comparison with CNIs (79-83%, 66% and 59-62%) respectively. Meta-analysis demonstrated lower recurrence (OR = 0.30, 95% CI = 0.16-0.55, P < 0.001), lower recurrence-related mortality (OR = 0.29, 95% CI = 0.12-0.70, P = 0.005) and lower overall mortality (OR = 0.35, 95% CI = 0.20-0.61, P < 0.001) for SRL group.

CONCLUSION

The review showed lower recurrence rate, longer recurrence-free survival and overall survival and lower recurrence-related mortality in sirolimus-treated patients in comparison with the calcineurin inhibitor-treated patients following liver transplantation for hepatocellular carcinoma.

Targeted agents and systemic therapy in hepatocellular carcinoma

Cytotoxic chemotherapy, hormonal agents, and immunotherapy have been tested in hepatocellular cancer (HCC) with marginal efficacy to date. Recent insights into the molecular pathogenesis of HCC have identified several aberrant signaling pathways that have served as targets for novel therapeutic agents. These discoveries have been translated into the clinical realm with the use of the antiangiogenic and the Raf kinase inhibitor, sorafenib, and have revealed the potential of targeted agents to produce clinically meaningful survival benefits in patients with advanced HCC. Efforts continue in the quest to improve the outcome of HCC patients through the development and evaluation of other targeted agents, and to better understand the interactions between the underlying disease biology and response to therapy. Several pathways are now implicated in hepatocarcinogenesis and agents that target these pathways continue to be developed.

Recurrent hepatocellular carcinoma after liver transplantation - an emerging clinical challenge

In western countries, hepatocellular carcinoma (HCC) is a major reason for orthotopic liver transplantation (OLT) with estimated recurrence rates between 15% and 20%. This selective literature review addresses follow-up care after OLT in HCC and current treatment options. Recurrence prediction is based on pathological tumor stage, vascular invasion, serum alfafetoprotein levels, and histological differentiation, but further advances are expected by molecular profiling techniques. Lower levels of immunosuppressive agents are associated with a lower risk for HCC recurrence. Retrospective studies indicate that mammalian target of rapamycin (mTOR) inhibitors as immunosuppression reduce the risk of HCC recurrence. However, prospective studies supporting this potential advantage of mTOR inhibitors are still lacking, and higher rejection rates were reported for sirolimus after OLT in HCC. Prognosis is poor in recurrent HCC, a longer interval between OLT and recurrence and feasibility of surgical resection are associated with improved survival. Systemic treatment with sorafenib is the current standard of care in patients with advanced-stage HCC not suitable for locoregional therapy. After OLT, combination of an mTOR inhibitor with sorafenib is feasible and frequently used in clinical practice. As safety and efficacy data are still limited, close clinical monitoring is mandatory.

Phase II study of sirolimus in treatment-naive patients with advanced hepatocellular carcinoma

BACKGROUND

Rapalogs are emerging as promising targeted anticancer drugs. Activation of the PI3K/Akt/mTOR pathway has been observed in 15-50% of hepatocellular carcinomas.

METHODS

In this phase II study, patients with advanced hepatocellular carcinoma and underlying cirrhosis received sirolimus (20 mg/week for 1 month then 30 mg/week). Tumour response was assessed every 8 weeks. The primary endpoint was the objective tumour response rate according to the Response Evaluation Criteria in Solid Tumours criteria. Secondary endpoints included the objective response according to the modified Response Evaluation Criteria in Solid Tumours criteria, safety, and pharmacokinetic parameters.

RESULTS

Twenty-five patients received sirolimus for a median of 20.6 weeks. Two patients had an objective response (8%, 95CI: 0.98-26.03), including one complete response, and 8 patients had stable disease. There were 2 cases of grade 5 toxicity (infections) and 5 cases of grade 3 toxicity. The main grade 1/2 toxicity was mild transient fatigue (76%). Median time to radiological progression and overall survival were 15.3 weeks (range: 8.2-173.9) and 26.4 weeks (range: 8.2-173.9) respectively. Use of the modified Response Evaluation Criteria in Solid Tumours criteria did not identify any further responders.

CONCLUSION

These data suggest that first-line sirolimus shows antitumoural efficacy in advanced hepatocellular carcinoma. Larger trials with Child A patients are needed.

[Liver transplantation: personalized immunosuppression in patients with hepatitis C virus infection and hepatocellular carcinoma]

Transplantation has become the treatment of choice in end-stage liver disease, with 5-year survival rates of around 68-74% in European and North-American registries (www.unos.org, www.eltr.org, www.ont.es). These results are largely due to the development of powerful immunosuppressive agents, mainly calcineurin inhibitors. However, these immunosuppressive drugs are not free of adverse effects, especially nephrotoxicity. Moreover, two of the most frequent indications for transplantation, cirrhosis due to hepatitis C virus and hepatocellular carcinoma, can recur in the transplanted graft. Whether specific immunosuppression could be less harmful in these conditions is the subject of debate. With the greater use of suboptimal donors and of expanded criteria for liver transplantation in patients with hepatocellular carcinoma, aggressive recurrences can be expected to increase. The present review attempts to elucidate whether there is an immunosuppression strategy that could minimize the risk of aggressive tumoral recurrence or recurrence of hepatitis C.

Activation of PI3K/AKT and MAPK pathway through a PDGFRβ-dependent feedback loop is involved in rapamycin resistance in hepatocellular carcinoma

BACKGROUND

Rapamycin is an attractive approach for the treatment and prevention of HCC recurrence after liver transplantation. However, the objective response rates of rapamycin achieved with single-agent therapy were modest, supporting that rapamycin resistance is a frequently observed characteristic of many cancers. Some studies have been devoted to understanding the mechanisms of rapamycin resistance, however, the mechanisms are cell-type-dependent and studies on rapamycin resistance in HCC are extremely limited.

METHODOLOGY/PRINCIPAL FINDINGS

The anti-tumor sensitivity of rapamycin was modest in vitro and in vivo. In both human and rat HCC cells, rapamycin up-regulated the expression and phosphorylation of PDGFRβ in a time and dose-dependent manner as assessed by RT-PCR and western blot analysis. Using siRNA mediated knockdown of PDGFRβ, we confirmed that subsequent activation of AKT and ERK was PDGFRβ-dependent and compromised the anti-tumor activity of rapamycin. Then, blockade of this PDGFRβ-dependent feedback loop by sorafenib enhanced the anti-tumor sensitivity of rapamycin in vitro and in an immunocompetent orthotopic rat model of HCC.

CONCLUSIONS

Activation of PI3K/AKT and MAPK pathway through a PDGFRβ-dependent feedback loop compromises the anti-tumor activity of rapamycin in HCC, and blockade of this feedback loop by sorafenib is an attractive approach to improve the anti-tumor effect of rapamycin, particularly in preventing or treating HCC recurrence after liver transplantation.

m-TOR inhibitors: what role in liver transplantation?

The development of calcineurin inhibitors (CNIs) led to marked improvements in patient and graft survival after liver transplantation (LTx). We have been left, however, with a dependence on immunosuppressive agents with nephrotoxicity, neurotoxicity, adverse impacts on cardiac risk profile, and risk for malignancy. These challenges need to be met against a dominance of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC) as indications for liver transplant. Unmet needs for immunosuppression (IS) in LTx include: (1) Effective drugs that avoid CNIs toxicities. (2) Agents without adverse impact on HCV recurrence. (3) Compounds that minimize risk of HCC recurrence. New immunosuppressives will need to address the above needs while supporting patient and graft survival equivalent to those achievable with CNIs, ideally without important new toxicities. Two new classes of agents are currently in advanced clinical development: belatacept, and the mammalian target of rapamycin inhibitors (m-TORi). This manuscript will review evidence for a role for m-TORi in LTx in a range of clinical scenarios including patients with CNI nephrotoxicity or neurotoxicity, patients at risk of (or with) HCV recurrence, and patients at risk of HCC recurrence.

Hepatocellular carcinoma and liver transplantation: clinical perspective on molecular targeted strategies

Hepatocellular carcinoma (HCC) has an aggressive clinical course with frequent recurrence and metastasis. Orthotopic liver transplantation has been the only curative tool for unresectable HCC; therefore, recent advances in molecular targeted therapy may improve the prognosis of HCC. The multiple kinase inhibitor sorafenib and the macrolide antibiotic rapamycin are currently the most promising agents for treating unresectable HCC. A large population-based clinical trial revealed that sorafenib significantly prolonged the overall survival of HCC patients. However, subsequent clinical studies showed that sorafenib rarely reduced tumor volume and inadequately prolonged survival of patients with severe liver damage. To improve its therapeutic effect, the development of a predictive biomarker and a sorafenib-based combination is awaited. Another molecular targeting agent, rapamycin, has now been considered as a putative agent for preventing tumor recurrence in post-liver transplantation HCC patients, because it not only has immunosuppressive activity but also exerts an anti-tumor effect. In the near future, a combination of molecular targeting agents, such as sorafenib and rapamycin, may become a standard protocol for treating unresectable HCC. For specifying cases with more effective and less harmful modalities, further investigation in clinical and basic research to identify unexpected effects are needed.

Influence of immunosuppressive drugs on the recurrence of hepatocellular carcinoma after liver transplantation: a gap between basic science and clinical evidence

Effects of immunosuppressive drug on tumor development in transplantation are understudied. Tumors are especially concerning when liver transplantation recipients have a pretransplant hepatocellular carcinoma (HCC). Because immunosuppressive drugs likely influence HCC recurrence, with mammalian target of rapamycin inhibitors showing antineoplastic properties especially experimentally, we sought for practical medical guidance from published clinical studies. Although the current literature review revealed 14 studies regarding immunosuppression in this context, suggesting antitumor effects for mammalian target of rapamycin inhibitors, the quality of evidence is low. Therefore, randomized controlled trials investigating effects of immunosuppression on HCC recurrence in liver transplantation are lacking, exposing a gap between basic science knowledge and clinical evidence.

Pilot study: rapamycin in advanced hepatocellular carcinoma

BACKGROUND

The PI3K/Akt/mTOR signal pathway is involved in hepatocarcinogenesis. Rapamycin (=sirolimus), a specific mTOR inhibitor, leads to G(1) arrest of many malignant cell lines and currently, analogues of rapamycin are being investigated as a cancer chemotherapeutic adjuvant.

AIM

To study the toxicity and tolerability of rapamycin therapy in patients with advanced hepatocellular carcinoma (HCC).

METHODS

Between June 2005 and February 2007, patients with advanced HCC, not eligible for any established therapy, were included in the study.

RESULTS

Eighteen patients (F/M: 5/13) with compensated liver cirrhosis (Child A n = 11, Child B n = 5, Child C n = 2) and histologically proven HCC were included in this study. According to the BCLC staging system, most of the patients enrolled had an advanced HCC: BCLC stage B: n = 2, Barcelona Clinic Liver-Cancer (BCLC) stage C: n = 14, BCLC stage D: n = 2. Overall, therapy with rapamycin was well tolerated. Most common toxicities were thrombocytopaenia and anaemia. We did not observe any partial or complete tumour response. At 3 months, two patients had stable disease and at 6 months, all patients had progressed. The median overall survival was 5.27 months, median time to progression was 3 months.

CONCLUSION

Rapamycin is well tolerated in patients with advanced HCC, but only minimally effective.

Impact of sirolimus on the recurrence of hepatocellular carcinoma after liver transplantation

Tumor recurrence after liver transplantation for hepatocellular carcinoma is associated with a poor prognosis. Because immunosuppression is a well-known risk factor for tumor growth, it is surprising that its possible role in the outcome of liver transplantation has been poorly evaluated. We performed a case-control review of prospectively collected data and compared 2 groups of patients according to the type of immunosuppression after liver transplantation for hepatocellular carcinoma at a single center. One hundred six patients received tacrolimus and mycophenolate mofetil, and 121 received sirolimus. Patients in the sirolimus group had significantly higher recurrence-free survival rates than patients in the tacrolimus group (P = 0.0003). The sirolimus group also had significantly higher patient survival rates than the tacrolimus group at 1 year (94% versus 79%), 3 years (85% versus 66%), and 5 years (80% versus 59%; P = 0.001). Sirolimus was well tolerated, and the patients in this study did not have the increase in surgical complications noted by other investigators. Leukopenia was the most common side effect, but it typically resolved with dose reduction. Dyslipidemia and mouth ulcers were common but were easily controlled. In summary, the data suggest a beneficial effect of sirolimus immunosuppression on recurrence-free survival, which translates into patient survival benefits.

Natural history and therapeutic management of recurrent hepatocellular carcinoma after liver transplantation

While the natural history and appropriate diagnostic and management practices are relatively well defined for hepatocellular carcinoma (HCC), data are scarce concerning the characteristic features and treatment modalities for recurrent HCC after liver transplantation. The time of recurrence appears to impact survival more significantly than localization, but to date, guidelines for therapeutic management of recurrent HCC have not been established. Data in the literature shows that late and unifocal recurrence has a better prognosis when treated by surgery or radiofrequency. In the event of early recurrence, surgery cannot be recommended due to the lack of evidence and the high risk of advanced disease. Systemic therapy can be discussed in a situation of multifocal recurrence. Proliferative signal inhibitors exhibit both immunosuppressive and antiproliferative properties and liver transplantation teams tend to introduce such treatment despite the lack of extensive data.

mTOR inhibitors for hepatocellular cancer: a forward-moving target

mTOR is a central regulator of cell growth and angiogenesis. The mTOR pathway is activated in 40-50% of patients with hepatocellular cancer (HCC). In different models (i.e., hepatoma cell lines and implanted HCC tumors in rats), mTOR inhibitors (mTORIs) were effective in reducing cell growth and tumor vascularity. Synergistic effects were observed for mTORIs and chemotherapeutic agents in these studies, while other combinations involving mTORIs and inhibitors of growth hormones and angiogenesis are awaiting further clinical testing. A number of mTORIs are already clinically available (e.g., sirolimus, temsirolimus and everolimus), sharing similiar pharmacokinetic parameters (except for absorption) and side effects. Clinical data are, as yet, only preliminary and are mainly derived from retrospective studies in patients who underwent liver transplantation for HCC. Those patients had received sirolimus thereafter for immunosuppression, and a much lower rate of tumor recurrence than with calcineurin inhibitors alone was noted. Current prospective trials for treatment of advanced HCC include mTORIs alone or in combination with either transarterial chemoembolization or other systemic drugs, and will be discussed in detail in this review.

Sirolimus-based immunosuppression therapy in liver transplantation for patients with hepatocellular carcinoma exceeding the Milan criteria

AIM

Sirolimus (SRL) acts as a primary immunosuppressant or antitumor agent. The aim of the present study was to evaluate the influence of SRL on the recurrence rate and survival of patients after orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC) exceeding the Milan criteria.

MATERIALS AND METHODS

We retrospectively examined 73 consecutive patients who underwent OLT for HCC exceeding the Milan criteria from March 2004 through December 2005. Among them, 27 patients were treated with SRL-based immunosuppressive protocols after OLT, and 46 patients by an FK506-based protocol. Statistical analysis was based on the intent-to-treat method.

RESULTS

The 2 groups were comparable in all clinicopathologic parameters. The mean overall survival was 594 +/- 35 days in the SRL group and 480 +/- 42 days in the FK506 group (P = .011); the mean disease-free survival period was 519 +/- 43 days in the SRL group and 477 +/- 48 days in the FK506 group (P = .234). Multivariate analysis revealed Child's status (P = .004) and immunosuppressive protocol (P = .015) were the significant factors affecting overall survival. Only microvascular invasion (P = .004) was significantly associated with disease-free survival. Among 24 surviving patient in the SRL group, 2 patients had SRL discontinued for toxicity; 10 had SRL monotherapy immunosuppression.

CONCLUSION

The SRL-based immunosuppressive protocol improved the overall survival of patients after OLT for HCC exceeding the Milan criteria, probably by postponing recurrence and with better tolerability.

The role of mTOR inhibitors in the management of posttransplant malignancy

Organ transplant recipients given mammalian target of rapamycin inhibitor (mTORi) have reduced incidence of de novo posttransplant malignancies (dNPTMs). Posttransplant Kaposi's sarcoma and nonmelanotic skin malignancies (NMSC) frequently undergo remission/regression after conversion to mTORi immunosuppression (IS), especially early, small, and low-grade lesions, whereas larger, aggressive, and metastatic skin tumors are less likely to respond. mTORi-based IS is effective and well tolerated in orthotopic liver transplant patients with hepatocellular carcinoma (HCC) achieving excellent survival and disease-free intervals, particularly with extended criteria tumors, although the evidence that mTORi prevents HCC recurrence after orthotopic liver transplantation is only suggestive. Regression of metastatic HCC and other tumors and various forms of posttransplant lymphoproliferative disease have occurred after mTOR conversion. Documentation of regression/remission of other solid-organ dNPTM (colon, stomach, breast, etc.) after mTORi conversion is essentially absent with only anecdotal reports lacking follow-up data. Unfortunately, there is not a single reported prospective clinical trial powered for looking at the effect of mTORi IS in transplant recipients. Nevertheless, reduced incidence of all of dNPTMs and remission/regression of the commonest posttransplant tumors with mTOR therapy are strong reasons to expand the use of mTORi.

Effect of rapamycin alone and in combination with sorafenib in an orthotopic model of human hepatocellular carcinoma

PURPOSE

Novel therapeutic strategies are needed to prevent the tumor recurrence or metastasis after liver transplantation for hepatocellular carcinoma (HCC). This study was to investigate the effect of rapamycin, alone and in combination with sorafenib, on HCC in vivo.

EXPERIMENTAL DESIGN

Xenograft of a highly metastatic human HCC tumor (LCI-D20) was used to evaluate primary tumor growth and lung metastasis after treatment with rapamycin alone or in combination with sorafenib. Tumor cell proliferation was determined by Ki-67 immunostaining. To detect tumor cell apoptosis, the terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay was used. Tumor angiogenesis was investigated by using a monoclonal anti-CD31 antibody. A vascular endothelial growth factor ELISA kit was used to measure vascular endothelial growth factor protein levels in the mice serum.

RESULTS

Rapamycin, alone and in combination with sorafenib, strongly inhibited primary tumor growth and lung metastases in LCI-D20 model. Furthermore, the combination therapy significantly enhanced the effect of antitumor on primary tumor growth compared with single treatment with either rapamycin (P < 0.001) or sorafenib (P < 0.001). Rapamycin alone inhibited HCC cell proliferation, induced apoptosis, and decreased tumor angiogenesis. Nevertheless, the combination therapy showed a significant inhibition of tumor cell proliferation (P < 0.05). Additionally, the combination therapy also further enhanced suppression of tumor cell angiogenesis compared with rapamycin treatment (P < 0.01). However, the induction of apoptosis in combination therapy group was not significantly higher than in the rapamycin-treated group (P > 0.05).

CONCLUSIONS

The combination therapy of rapamycin and sorafenib could be a new and promising therapeutic approach to the treatment of HCC and prevention of HCC recurrence after liver transplantation.

Impact of rapamycin on liver regeneration

The remarkable capacity of the liver to regenerate after injury and the prospects of organ self-renewal have attracted much interest in the understanding and modulation of the underlying molecular events. We investigated the effect of mammalian target of rapamycin (mTOR) inhibitor rapamycin (RAPA) on liver by correlating intravital microscopy, immunohistochemistry, and reverse transcriptase polymerase chain reaction in a rat model of 2/3 hepatectomy. RAPA significantly retarded proliferation of hepatocytes, endothelial cells, and hepatic stellate cells (HSCs) mostly between days 2 and 4 after hepatectomy and downregulated major cytokines and growth factors (tumor necrosis factor alpha, hepatocyte growth factor, platelet-derived growth factor, platelet-derived growth factor receptor, insulin-like growth factor-1, transforming growth factor beta 1) important for liver regeneration. These effects were almost absent at later time points. RAPA also had a transient, but broad effect on angiogenesis, and impaired sinusoidal density as well as mRNA levels of vascular endothelial growth factor, vascular endothelial growth factor receptor 1, vascular endothelial growth factor receptor 2, and angiopoietin-1. Activation of HSC was also transiently suppressed as observed by smooth muscle protein 1 alpha protein expression and intercellular adhesion molecule-1 mRNA levels. The rate of apoptosis in liver was significantly increased by RAPA between day 3 and day 7. The effect of RAPA on liver repair, angiogenesis, and HSC activation is confined to the phase of active cell proliferation. This transient effect might allow further exploration of mTOR inhibitors in clinical situations that involve liver regeneration, and seems to have implications beyond immunosuppression.

Sirolimus-based immunosuppression following liver transplantation for hepatocellular carcinoma

Experience with sirolimus (SRL)-based immunosuppression following orthotopic liver transplantation (OLT) is rapidly accumulating. In combination with calcineurin inhibitors (CNIs), SRL may reduce the incidence of acute rejection and lower overall required drug levels. This study sought to quantify long-term outcome following OLT in patients with cirrhosis and concomitant hepatocellular carcinoma (HCC) who were treated with an SRL-based regimen as a primary therapy. From January 2000 to June 2007, 97 patients underwent OLT for end-stage liver disease and HCC at the University of Colorado Health Sciences Center. Of those, 45 patients received SRL, in addition to CNIs, as a component of their primary immunosuppression regimen post-OLT. Conversely, 52 patients received the standard immunosuppression regimen including CNIs, mycophenolate mofetil, and corticosteroids. The 2 treatment groups were compared with respect to the following variables: age, gender, tumor stage by explant, grade, size, presence of vascular invasion, focality, Child's class, baseline creatinine, and warm and cold ischemic times. The 2 groups were comparable by all factors save for cold ischemic time, which was significantly longer in the CNI-treated group. Overall survival at 1 and 5 years post-OLT for patients treated with SRL was 95.5% and 78.8%, respectively. Conversely, survival in patients treated with CNIs exclusively at the same time intervals was 83% and 62%. Although there was no difference in the incidence of major complications, the SRL group experienced a modest improvement in renal function. Cumulatively, these data suggest a potential survival benefit with SRL-based therapy in patients undergoing OLT for end-stage liver disease and concomitant malignancy.

Liver transplantation in the setting of extra-hepatic malignancy: two case reports

Candidates for liver transplantation (OLT) may be found to have an incidental extrahepatic tumor, which is amenable to resection, and may be associated with variable long-term survival. Issues to be considered include: (1) Whether it is possible to define a tumor stage and survival expectancy, which makes the patient an acceptable transplant candidate; (2) Whether cancer surgery should be preformed prior, during, or after OLT; (3) Whether the recipient be placed on immunosuppression that is tailored to address concern related to cancer recurrence. These issues are illustrated in the context of OLT and nephrectomy for renal cell carcinoma (RCC). Two patients underwent a simultaneous OLT and curative radical nephrectomy for stage 1 RCC that was incidentally discovered during OLT evaluation, one of whom received a simultaneous kidney transplant. At 51 and 14 months postoperatively, the patients are alive and healthy, with no tumor recurrence. In selected extrahepatic malignancies, simultaneous curative resection and OLT may provide the optimal outcome. This is justifiable when curative cancer-related life expectancy exceeds OLT-expected graft and patient survival. Concomitant transplantation and cancer surgery provides an acceptable cancer-free survival, avoiding the high morbidity observed when cancer resection is done in the presence of decompensated liver disease.

From molecular biology to targeted therapies for hepatocellular carcinoma: the future is now

Hepatocellular carcinoma (HCC) is characterized as a highly chemoresistant cancer with no effective systemic therapy. Despite surgical or locoregional therapies, prognosis remains poor because of high tumor recurrence or tumor progression, and currently there are no well-established effective adjuvant therapies. The molecular biology of carcinogenesis and tumor progression of HCC has been increasingly understood with intense research in recent years. Several important intracellular signaling pathways such as the Ras/Raf/Mek/Erk pathway and PI3k/Akt/mTOR pathway have been recognized, and the role of several growth factors and angiogenic factors such as EGF and VEGF has been confirmed. Effective agents targeting these molecular abnormalities have been developed and widely tested in preclinical studies of HCC cell lines or xenograft models. Several agents have entered clinical trials in HCC patients, and recent data indicated that a multikinase inhibitor targeting Ras kinase and VEGFR-2, sorafenib, is effective in prolonging survival of patients with advanced HCC. The management of advanced HCC is entering the era of molecular targeting therapy, which is of particular significance for HCC in view of the lack of existing effective systemic therapy for this cancer.

Emerging approaches in hepatocellular carcinoma

The incidence of hepatocellular carcinoma (HCC) is predicted to continue to increase over the next 30 years. Surgical intervention, including resection and orthotopic liver transplantation (OLT) is offered to a limited number of patients. Novel approaches to the treatment of patients with HCC are needed. This article aims to review emerging approaches in the care of the HCC patient including systemic treatment, selection of appropriate candidates for OLT, improved imaging to follow treatment response, and management pre-OLT and post-OLT.

Predictors of long-term outcome following liver transplantation for hepatocellular carcinoma: a single-center experience

Orthotopic liver transplantation (OLT) is increasingly being applied for cure in patients with cirrhosis and concomitant hepatocellular carcinoma (HCC). In recipients with limited tumor burden, OLT achieves reasonable long-term outcome. This study sought to identify clinical and pathologic variables predictive of long-term disease-free survival and the presence of vascular invasion. From 1992 to 2006, 130 patients underwent OLT for cirrhosis and HCC. Malignancy was diagnosed in 107 patients prior to OLT and in 23 patients on pathologic examination of the explant. Nine clinical and pathologic variables were considered including: TNM stage, nodularity, vascular invasion, Milan criteria, incidental lesion, differentiation, tumor size, preOLT transarterial chemoembolization (TACE), and administration of sirolimus-based immunosuppression. The overall incidence of HCC recurrence was 17% with the majority (82%) being stage III. Cumulatively, tumor recurrence-free survival (RFS) is 84, 74, and 67% at 1, 3, and 5 years respectively. Independent predictors of RFS included stage III and poorly differentiated lesions (P<0.05). Furthermore, stage III tumors and those >3.5 cm in size were predictive of vascular invasion. Importantly, preOLT, TACE and postOLT sirolimus had no influence on survival. Pathologic variables including tumor stage and grade have a significant impact on outcome. Importantly, it seems that TACE and sirolimus had no beneficial effect.

Strategies for the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) generally develops as a consequence of underlying liver disease, most commonly viral hepatitis. The development of HCC follows an orderly progression from cirrhosis to dysplastic nodules to early cancer development, which can be reliably cured if discovered before the development of vascular invasion (typically occurring at a tumor diameter of approximately 2 cm). The identifiable population at risk makes screening a realistic possibility, and liver imaging is recommended every 6 months for patients with cirrhosis. For patients with preserved liver function and no portal hypertension who develop HCC that is confined to one region of the liver, resection is the preferred treatment. If resection is not possible because of poor liver function, and the HCC is within the Milan criteria (1 nodule > or =5 cm, 2-3 nodules > or =3 cm), liver transplantation is the treatment of choice. To prevent tumor progression while waiting, nonsurgical treatments including percutaneous ethanol injection, radiofrequency ablation, and transarterial chemoembolization are employed, but drop-out from the waiting list remains a problem. Living donor transplantation is an alternative that can eliminate drop-out and enable liver transplantation for patients with HCC whose disease does not fall within the Milan criteria. There is a need for more effective adjuvant therapies after resection and liver transplantation; newer antiangiogenic agents offer hope for improved outcomes in the future.

Sirolimus and liver transplantation: clinical implications for hepatocellular carcinoma

Sirolimus (SRL) is a macrolide antibiotic that has potent antifungal and immunosuppressive properties; preclinical studies suggest that SRL may possess a significant antiproliferative influence in vitro. Recently, several studies have documented a negative effect by SRL on both primary tumor growth and the proliferation of metastatic foci in various rodent models of hepatocellular carcinoma (HCC). Orthotopic liver transplantation (OLT) is increasingly becoming a viable treatment option for patients with end stage liver disease and concomitant HCC. As such, an immunosuppressive agent with antineoplastic activity is inherently attractive in the setting of OLT for malignancy. Regrettably, the cumulative experience with SRL-based immunosuppression in this patient population is limited. Herein, the authors review the experience to date with SRL as a primary immunosuppressive agent following OLT, and discuss the clinical implications of SRL-based therapy in OLT recipients with cirrhosis and cancer.

Complete Regression of Cutaneous B-Cell Lymphoma in a Renal Transplant Patient After Conversion From Cyclosporin to Sirolimus

Posttransplant lymphoproliferative disease remains a serious morbidity. Herein we have reported a case of complete regression of a biopsy-proven B-cell lymphoma that occurred in the posttransplant period. A 48-year-old man received a living donor renal transplant for end-stage renal disease due to undetermined etiology. His initial immunosuppression consisted of corticosteroid, mycophenolate mofetil, and cyclosporin. The patient developed severe pneumonia within the first 2 months after transplantation due to Acineotobacter, fungus, and cytomegalovirus infections. He experienced a complete recovery and was discharged for regional follow-up. Four months after discharge, he was referred again because of presence of two nodules on his trunk. A biopsy of the nodules revealed B-cell lymphoma. Cyclosporin was stopped and he was converted to sirolimus. The lesions regressed progressively and completely within 7 weeks. The patient remains well without clinical relapses at 19 months after conversion. Renal functions remained stable. We postulated that the antincoplastic properties of sirolimus may have played an active part in the positive outcome.

Mammalian target of rapamycin pathway activity in hepatocellular carcinomas of patients undergoing liver transplantation

BACKGROUND

Because mammalian target of rapamycin (mTOR) inhibitors combine anticancer and immunosuppressive properties we investigated: 1) the activation status and prognostic significance of the mTOR pathway in hepatocellular carcinoma (HCC) tissues of patients undergoing orthotopic liver transplantation (OLT) for HCC, and 2) the single and combinatorial efficacy of RAD001 in HCC cells.

METHODS

PTEN, p-AKT, p-mTOR, p-p70S6K, and p-4EBP-1 were analyzed by immunohistochemistry in explanted HCCs of 166 patients undergoing OLT. Efficacy of RAD001 as mono- and combination therapy with doxorubicin was tested in Hep3B and SNU398 cells.

RESULTS

The mTOR pathway is activated in about 40% of patients undergoing OLT for HCC but no direct correlation between up- and downstream proteins was observed. We found no influence of mTOR pathway protein expression on disease free survival (DFS) or overall survival (OS). There was a marked single agent and chemo-sensitizing effect of RAD001 against HCC cells in vitro.

CONCLUSION

The mTOR pathway is active in 40% of patients with HCC undergoing OLT, but has no influence of DFS or OS. No direct correlation was observed between up- and downstream proteins limiting the use of upstream proteins to predict mTOR activity. Prospective clinical trials are needed to test whether the activation status of the mTOR pathway in HCCs predicts the antitumor effect of rapamycin derivative in the posttransplantation course.