Pembrolizumab for metastatic hepatocellular carcinoma following live donor liver transplantation: The silver bullet?

Immune checkpoint inhibitors in liver transplantation: Current practice, challenges, and opportunities

Immune checkpoint inhibitors are becoming a mainstay of cancer treatment. While first studied and approved for patients with unresectable disease, due to their efficacy, they are becoming increasingly used in the perioperative period across many cancer types. In patients with HCC, immune checkpoint inhibitors have now become the standard of care in the advanced setting and have shown promising results in the adjuvant setting after liver resection. While these drugs continue to show promise, their role in the peritransplant setting still remains a question. In this review, we explore the current use of this class of medications in patients with HCC, as well as the immunologic role of the pathways that they inhibit. We also identify potential for future research opportunities to better understand the role of these medications.

Liver Transplantation for Hepatocellular Carcinoma in the Era of Immune Checkpoint Inhibitors

Hepatocellular carcinoma (HCC) remains the leading oncological indication for liver transplantation (LT), with evolving and broadened inclusion criteria. Immune checkpoint inhibitors (ICIs) gained a central role in systemic HCC treatment and showed potential in the peri-transplant setting as downstaging/bridging therapy before LT or as a treatment for HCC recurrence following LT. However, the antagonistic mechanisms of action between ICIs and immunosuppressive drugs pose significant challenges, particularly regarding the risk of acute rejection (AR). This review analyzes the main signaling pathways targeted by ICI therapies and summarizes current studies on ICI therapy before and after LT. The literature on this topic is limited and highly heterogeneous, precluding definitive evidence-based conclusions. The use of ICIs before LT appears promising, provided that a sufficient wash-out period is implemented. In contrast, the results of post-LT ICI therapy do not support its wide clinical application due to high AR rates and overall poor response to treatment. In the future, modern graft preservation techniques might support the selection of good ICI responders, but data from high-level studies are urgently needed.

Immunotherapy for transplantation of hepatocellular carcinoma: the next frontier in adjunctive therapy

PURPOSE OF REVIEW

The increasing success of liver transplantation in hepatocellular carcinoma (HCC) drives an ever-evolving search for innovative strategies to broaden eligible patients' pools. Recent advances in immuno-oncology have turned the spotlight on immune checkpoint inhibitors (ICIs). This review offers an updated overview of ICIs in liver transplantation for HCC, exploring neoadjuvant and adjuvant approaches and addressing unanswered questions on safety, patients' selection, and response predictors.

RECENT FINDINGS

ICIs have transitioned from being a last-chance therapeutic hope to becoming an integral cornerstone in the treatment of advanced HCC, holding great promise as a compelling option not only to downstage patients for transplantation but also as an alternative strategy in addressing posttransplantation disease recurrence. Despite ongoing refinements in immunotherapeutic agents, the complex molecular pathways involved emphasize the need for a comprehensive approach to integrate immunotherapy in liver transplantation.

SUMMARY

Initial concerns about graft rejection, with ICIs as a bridging therapy to liver transplantation, were successfully addressed using adequate immunosuppressants strategies and minimized with a sufficient washout period. Post-liver transplantation disease recurrence remains challenging, requiring a balance between effective therapy and preserving graft function. Emphasis should be placed on clinical trials validating the risk-benefit ratio of ICIs for liver transplantation, guiding appropriate patients' selection, and establishing clear management pathways.

Immunotherapy and Liver Transplantation: The Future or the Failure?

A quarter century has passed since the milestone study by Mazzaferro and colleagues on liver transplantation (LT) for hepatocellular carcinoma (HCC). The increasing demand for LT for HCC has led to the continued efforts to expand LT indications. Downstaging to within Milan criteria has been incorporated into the organ allocation policy for HCC in the United States in 2017 and provides acceptable long-term survival. The present review focuses on the rationale of neoadjuvant immune checkpoint inhibitor (ICI) in HCC, the experience of ICI in the pre- and posttransplant setting.

Transplant Oncology: An Emerging Discipline of Cancer Treatment

Transplant oncology is an emerging concept of cancer treatment with a promising prospective outcome. The applications of oncology, transplant medicine, and surgery are the core of transplant oncology to improve patients' survival and quality of life. The main concept of transplant oncology is to radically cure cancer by removing the diseased organ and replacing it with a healthy one, aiming to improve the survival outcomes and quality of life of cancer patients. Subsequently, it seeks to expand the treatment options and research for hepatobiliary malignancies, which have seen significantly improved survival outcomes after the implementation of liver transplantation (LT). In the case of colorectal cancer (CRC) in the transplant setting, where the liver is the most common site of metastasis of patients who are considered to have unresectable disease, initial studies have shown improved survival for LT treatment compared to palliative therapy interventions. The indications of LT for hepatobiliary malignancies have been slowly expanded over the years beyond Milan criteria in a stepwise manner. However, the outcome improvements and overall patient survival are limited to the specifics of the setting and systematic intervention options. This review aims to illustrate the representative concepts and history of transplant oncology as an emerging discipline for the management of hepatobiliary malignancies, in addition to other emerging concepts, such as the uses of immunotherapy in a peri-transplant setting as well as the use of circulating tumor DNA (ctDNA) for surveillance post-transplantation.

Immunotherapy and Liver Transplantation: A Narrative Review of Basic and Clinical Data

Immune checkpoint inhibitors (ICIs) have improved the management of patients with intermediate- and advanced-stage HCC, even making some of them potential candidates for liver transplantation. However, acute rejection has been observed after ICI therapy, challenging its safety in transplant settings. We summarize the key basic impact of immune checkpoints on HCC and liver transplantation. We analyze the available case reports and case series on the use of ICI therapy prior to and after liver transplantation. A three-month washout period is desirable between ICI therapy and liver transplantation to reduce the risk of acute rejection. Whenever possible, ICIs should be avoided after liver transplantation, and especially so early after a transplant. Globally, more robust prospective data in the field are required.

Progress of PD-1/PD-L1 signaling in immune response to liver transplantation for hepatocellular carcinoma

Primary liver cancer is one of the most common malignant tumors in China. The vast majority of primary liver cancer are hepatocellular carcinoma. Due to its high incidence and mortality from HCC, HCC has always been a feared type of cancer. Liver transplantation, as one of the important means to treat advanced liver cancer, has brought new hope to patients. However, as patients have been in a state of immunosuppression after liver transplantation, these patients face new problems of HCC recurrence and metastasis. A increasing number of studies have proved that blocking the PD-1/PD-L1 signaling pathway and restoring the immune killing inhibition of T cells can produce better therapeutic effects on tumors and chronic infectious diseases. As a promising treatment in the field of tumor immunotherapy, PD-1/PD-L1 inhibitors have achieved important results in liver cancer patients, but their application in liver transplantation patients is still highly controversial. This paper will introduce the mechanism of action of PD-1/PD-L1 signaling pathway and the current basic and clinical studies of PD-1/PD-L1 signaling pathway associated with immune response in HCC transplantation.

Evolving Landscape in Liver Transplantation for Hepatocellular Carcinoma: From Stage Migration to Immunotherapy Revolution

Liver transplantation (LT) represents the primary curative option for HCC. Despite the extension of transplantation criteria and conversion with down-staging loco-regional treatments, transplantation is not always possible. The introduction of new standards of care in advanced HCC including a combination of immune checkpoint inhibitor-based therapies led to an improvement in response rates and could represent a promising strategy for down-staging the tumor burden. In this review, we identify reports and series, comprising a total of 43 patients who received immune checkpoint inhibitors as bridging or down-staging therapies prior to LT. Overall, treated patients registered an objective response rate of 21%, and 14 patients were reduced within the Milan criteria. Graft rejection was reported in seven patients, resulting in the death of four patients; in the remaining cases, LT was performed safely after immunotherapy. Further investigations are required to define the duration of immune checkpoint inhibitors, their minimum washout period and the LT long-term safety of this strategy. Some randomized clinical trials including immunotherapy combinations, loco-regional treatment and/or tyrosine kinase inhibitors are ongoing and will likely determine the appropriateness of immune checkpoint inhibitors' administration before LT.

Liver transplantation immunology: Immunosuppression, rejection, and immunomodulation

Outcomes after liver transplantation have continuously improved over the past decades, but long-term survival rates are still lower than in the general population. The liver has distinct immunological functions linked to its unique anatomical configuration and to its harbouring of a large number of cells with fundamental immunological roles. The transplanted liver can modulate the immunological system of the recipient to promote tolerance, thus offering the potential for less aggressive immunosuppression. The selection and adjustment of immunosuppressive drugs should be individualised to optimally control alloreactivity while mitigating toxicities. Routine laboratory tests are not accurate enough to make a confident diagnosis of allograft rejection. Although several promising biomarkers are being investigated, none of them is sufficiently validated for routine use; hence, liver biopsy remains necessary to guide clinical decisions. Recently, there has been an exponential increase in the use of immune checkpoint inhibitors due to the unquestionable oncological benefits they provide for many patients with advanced-stage tumours. It is expected that their use will also increase in liver transplant recipients and that this might affect the incidence of allograft rejection. Currently, the evidence regarding the efficacy and safety of immune checkpoint inhibitors in liver transplant recipients is limited and cases of severe allograft rejection have been reported. In this review, we discuss the clinical relevance of alloimmune disease, the role of minimisation/withdrawal of immunosuppression, and provide practical guidance for using checkpoint inhibitors in liver transplant recipients.

Immune checkpoint inhibitors in liver transplant: a case series

BACKGROUND

Immune checkpoint inhibitors (ICIs) in the setting of liver transplant (LT) pose a risk of rejection and hold unclear benefit in both the neoadjuvant (pre-transplant) and post-transplant salvage setting. In the pre-transplant setting, neoadjuvant ICIs may serve as a bridge to LT by downstaging disease burden to fit within transplant criteria. Outcomes in this setting include patients who had successful transplants without complications to patients who suffered severe complications, including fatal hepatic necrosis and graft failure requiring re-transplant. Some authors suggest having a period of three months between checkpoint inhibition and transplant may help mitigate adverse effects. In the post-LT setting, there are few treatment options if there is a recurrence of disease, which forces treatment teams to reconsider checkpoint inhibitors. Again, a longer period of time between transplant and checkpoint inhibition may reduce risk of rejection. Case reports of patients treated with ICIs post-transplant utilized either nivolumab or pembrolizumab. As combination atezolizumab/bevacizumab is a relatively new treatment option for unresectable hepatocellular carcinoma (HCC), there are only three reported cases using this combination in the post-LT setting. While there were no cases of rejection, all three cases had progression of disease. As immunotherapy joins transplantation as a mainstay of treatment for HCC, it remains unclear how to best navigate when the treatment course involves both immune activation and immunosuppression.

CASE DESCRIPTION

Patients who had an LT and were treated with ICIs (pre or post LT) at the University of Cincinnati were included in this retrospective chart review.

CONCLUSIONS

Fatal rejection remains a significant risk even 4 years after LT. Neoadjuvant ICIs also pose a risk for acute cellular rejection; however, this may not always be clinically significant. Graft versus host disease (GVHD) may be an additional, previously unreported risk of ICIs in the setting of LT. Prospective studies are needed to understand benefits and risks of checkpoint inhibitors in the LT setting.

Immune Checkpoint Inhibitors for Solid Tumors in the Adjuvant Setting: Current Progress, Future Directions, and Role in Transplant Oncology

The rationale for administering immune checkpoint inhibitors (ICIs) in the adjuvant setting is to eradicate micro-metastases and, ultimately, prolong survival. Thus far, clinical trials have demonstrated that 1-year adjuvant courses of ICIs reduce the risk of recurrence in melanoma, urothelial cancer, renal cell carcinoma, non-small cell lung cancer, and esophageal and gastroesophageal junction cancers. Overall survival benefit has been shown in melanoma while survival data are still not mature in other malignancies. Emerging data also show the feasibility of utilizing ICIs in the peri-transplant setting for hepatobiliary malignancies. While ICIs are generally well-tolerated, the development of chronic immune-related adverse events, typically endocrinopathies or neurotoxicities, as well as delayed immune-related adverse events, warrants further scrutiny regarding the optimal duration of adjuvant therapy and requires a thorough risk-benefit determination. The advent of blood-based, dynamic biomarkers such as circulating tumor DNA (ctDNA) can help detect minimal residual disease and identify the subset of patients who would likely benefit from adjuvant treatment. In addition, the characterization of tumor-infiltrating lymphocytes, neutrophil-to-lymphocyte ratio, and ctDNA-adjusted blood tumor mutation burden (bTMB) has also shown promise in predicting response to immunotherapy. Until additional, prospective studies delineate the magnitude of overall survival benefit and validate the use of predictive biomarkers, a tailored, patient-centered approach to adjuvant ICIs that includes extensive patient counseling on potentially irreversible adverse effects should be routinely incorporated into clinical practice.

Immunotherapy for Hepatocellular Carcinoma in the Setting of Liver Transplantation: A Review

The emerging field of immuno-oncology has brought exciting developments in the treatment of hepatocellular carcinoma (HCC). It has also raised urgent questions about the role of immunotherapy in the setting of liver transplantation, both before and after transplant. A growing body of evidence points to the safety and efficacy of immunotherapeutic agents as potential adjuncts for successful down-staging of advanced HCCs to allow successful transplant in carefully selected patients. For patients with recurrent HCC post-transplant, immunotherapy has a limited, yet growing role. In this review, we describe optimal regimens in the setting of liver transplantation.

Immunotherapy for hepatocellular carcinoma recurrence after liver transplantation, can we harness the power of immune checkpoint inhibitors?

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death globally and liver transplantation (LT) can serve as the best curative treatment option. However, HCC recurrence after LT remains the major obstacle to the long-term survival of recipients. Recently, immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many cancers and provided a new treatment strategy for post-LT HCC recurrence. Evidence has been accumulated with the real-world application of ICIs in patients with post-LT HCC recurrence. Notably, the use of these agents as immunity boosters in recipients treated with immunosuppressors is still controversial. In this review, we summarized the immunotherapy for post-LT HCC recurrence and conducted an efficacy and safety evaluation based on the current experience of ICIs for post-LT HCC recurrence. In addition, we further discussed the potential mechanism of ICIs and immunosuppressive agents in regulating the balance between immune immunosuppression and lasting anti-tumor immunity.

Immune checkpoint inhibitors in malignancies after liver transplantation: A systematic review and pooled analysis

BACKGROUND AND AIMS

Treatment of de novo malignancies and recurrent hepatocellular carcinoma with immune checkpoint inhibitors (ICI) in liver transplant recipients (LT) is an attractive strategy that is infrequently pursued because of the lack of strong evidence regarding their safety and efficacy. In this systematic review with pooled analysis, we aimed to assess safety and efficacy of ICI therapy following LT.

METHODS

We performed a systematic search of case reports and series published until January 2022. We included 31 publications reporting a total of 52 patients treated with ICIs after LT and assessed in a pooled analysis the risk of graft rejection and the outcome of ICI therapy.

RESULTS

Acute graft rejection occurred in 15 patients (28.8%) and 7 patients (13.4% of the total cohort) died because of graft loss. Rejection was associated with shorter overall survival (OS) (17.2 months, confidence interval [CI] 12.1-22.2 vs. 3.5 months, CI 1.6-5.4, p < 0.001). Disease control rate was 44.2% (n = 23), and in these patients, OS was longer than in non-responders (26.4 months, CI 20.8-32.0 vs. 3.4 months, CI 2.1-4.7, p < 0.001).

CONCLUSIONS

Observational, off-label experience suggests that treatment with ICI for advanced malignancies in LT recipients might not be discarded a priori. This notwithstanding, ICI treatment in these patients is associated with a substantial risk of graft rejection and mortality. Prospective studies are needed to provide adequate safety and efficacy figures of ICI treatment in this fragile population.

Immune microenvironment and therapeutic progress of recurrent hepatocellular carcinoma after liver transplantation

HCC is a highly lethal tumor, and orthotopic liver transplantation, as one of the radical treatment methods for HCC, has opened-up a new therapeutic approach for the treatment of primary liver cancer. However, tumor recurrence after liver transplantation is the main reason that affects the long-term survival of recipients. At present, the application of ICIs has brought dawn to patients with refractory HCC. However, because of the special immune tolerance state created by long-term oral immunosuppressants in patients with HCC after liver transplantation, the current focus is how to regulate the immune balance of such patients and simultaneously maximize the anti-tumor effect. This article reviews the relationship between liver cancer and immunity, immune tolerance of liver transplantation, immune microenvironment after liver transplantation for HCC, and the application of immunotherapy in the recurrence of liver transplantation for HCC.

Immune checkpoint inhibitor therapy for malignant tumors in liver transplantation recipients: A systematic review of the literature

BACKGROUND

Treatment for de novo or recurrent tumors of liver transplantation (LT) recipients is challenging and immune checkpoint inhibitor (ICI) is recently well developed and could be a potentially effective option for this population. There remains limited evidence on the safety and efficacy of ICI therapy in LT recipients.

METHODS

A systematic literature search was conducted on PubMed database through April 1, 2022, to identify publications reporting ICI treatment for malignant tumors in LT recipients. We summarized the allograft rejection, mortality, and tumor response of ICI treatment.

RESULTS

24 articles with 41 LT recipients were identified. The age of LT recipients ranged from 14 to 78, 76.2% were male, 56.1% had recurrent HCC, and 87.8% received anti-PD-1 therapy. Allograft rejection occurred in 31.7% of patients, death was reported in 46.3% and 6 cases died secondary to allograft rejection. Progressive disease rate of this population was 48.8% and 10 patients responded to immunotherapy. Half of recipients with positive PD-L1 staining (4/8) experienced allograft rejection.

CONCLUSIONS

ICI therapy has potential therapeutic value on malignant tumors for LT recipients, accompanied by a high rate of allograft rejection and mortality. PD-L1 expression, type of ICI, and immunosuppression agent should be taken into consideration before initiation of immunotherapy. Further studies are needed to optimize this anticancer treatment approach in these patients.

Low-dose PD-1 inhibitor combined with lenvatinib for preemptive treatment of recurrence after liver transplantation for hepatocellular carcinoma: Case report and literature review

Orthotopic liver transplantation (OLT), as one of the curative methods for the treatment of hepatocellular carcinoma (HCC), has brought hope to patients with HCC. However, treatment options for HCC recurrence and metastasis after liver transplantation are limited. Immune checkpoint inhibitor (ICI), such as programmed cell death protein 1 (PD-1) inhibitor, have been successfully used in advanced or metastatic HCC, but the data on the safety of PD-1 inhibitor after liver transplantation is limited. In this article, we report a 47-year-old patient with acute-on-chronic liver failure and multiple HCC who was successfully treated with liver transplantation. On the 45th day after OLT, the patient’s alpha fetoprotein (AFP) and lens culinaris agglutinin-reactive fraction of AFP (AFP-L3) were increased, and imaging examination showed no residual tumor. The patient had high risk factors for tumor recurrence before operation, so the possibility of tumor recurrence was considered. When the tumor markers showed an upward trend, we immediately treated the patient with lenvatinib 8 mg, after half a month, the AFP and AFP-L3 continued to increase compared with before. Then we used low-dose nivolumab 40mg, the patient’s AFP and AFP-L3 gradually decreased. One month later, a second low-dose nivolumab 40mg was given, and the patient’s tumor markers gradually decreased to normal. No acute rejection and other complications occurred during the treatment. So far, we have followed up this patient for 2 years, and no tumor recurrence was observed. To our knowledge, this is the first reported case using a low dose of nivolumab in combination with lenvatinib to prevent recurrence of HCC after liver transplantation.

Current perspectives on the role of liver transplantation for Langerhans cell histiocytosis: A narrative review

Langerhans cell histiocytosis (LCH) is a malignant disease of the histiocytes involving various organ systems. The spectrum of liver involvement in LCH ranges from mild transaminitis to end-stage liver disease. The hallmark of hepatic LCH is secondary sclerosing cholangitis, which manifests due to a progressive destruction of the biliary tree by malignant histiocytes. Chemotherapy remains the mainstay of treatment for active LCH. Early recognition, diagnosis and a systematic approach to the management of LCH can ameliorate the disease process. Nonetheless, the liver involvement in these patients may progress despite the LCH being in remission. Liver transplantation (LT) remains central in the management of such patients. Various facets of the management of LCH, especially those with liver involvement remain unclear. Furthermore, aspects of LT in LCH with regards to the indication, timing and post-LT management, including immunosuppression and adjuvant therapy, remain undefined. This review summarises the current evidence and discusses the practical aspects of the role of LT in the management of LCH.

Immune checkpoint inhibitors for solid organ transplant recipients: clinical updates

Transplant care continues to advance with increasing clinical experience and improvements in immunosuppressive therapy. As the population ages and long-term survival improves, transplant patient care has become more complex due to comorbidities, frailty, and the increased prevalence of cancer posttransplantation. Immune checkpoint inhibitors (ICIs) have become a standard treatment option for many cancers in non-transplant patients, but the use of ICIs in transplant patients is challenging due to the possibility of disrupting immune tolerance. However, over the past few years, ICIs have gradually started to be used in transplant patients as well. In this study, we review the current use of ICIs after all solid organ transplantation procedures (kidney, liver, heart, and lung). Increasing data suggest that the type and number of immunosuppressants may affect the risk of rejection after immunotherapy. Immunotherapy for cancer in transplant patients may be a feasible option for selected patients; however, prospective trials in specific organ transplant recipients are needed.

Liver transplantation for patients with hepatocellular carcinoma: Its current status and advances

Liver transplantation is one of the best treatment options for selected patients with hepatocellular carcinoma (HCC). The Milan criteria (a single tumor with a maximum size of 5 cm or two or three tumors with a maximum size of 3 cm without evidence of vascular or extrahepatic involvement or metastasis) are one of the most common criteria to select patients with HCC for transplantation, though they are considered too restrictive. A moderate expansion of the criteria has been found to yield comparable recurrence-free survival rates. HCC will recur in approximately 10% of patients, and mostly within the first 2 years after transplantation. The preoperative level of alpha-fetoprotein, macrovascular invasion, tumor size, and tumor number are prognostic factors for recurrence. Recurrence of HCC after transplantation results in a poor prognosis.

An analysis report on the application of immune checkpoint inhibitors after liver transplantation

Up to now, a variety of immune checkpoint inhibitors (ICIs) have been proved to have good therapeutic effects in the treatment of hepatocellular carcinoma (HCC). However, the effects of their applications in liver transplant (LT) recipients are still unclear. In this analysis report, the clinical applications and therapeutic effects of ICIs on LT recipients with hepatic tumor recurrence or de novo carcinoma based on eight databases, including PubMed, EMBASE, Web of Science, Google Scholar, China National Knowledge Infrastructure, Wanfang Data, and CQVIP, were investigated. And the prior treatment, disease response, adverse reactions, and prognosis of patients with malignant tumors after LT and receiving ICI treatments were analyzed. After screening, a total of 28 articles with 47 recipients on the application of ICIs after LT were included. In these patients, their median age was 57 (14–71) years and the main type of tumor after LT was HCC (59.6%). The overall remission rate following ICI treatment was 29.8% (14/47) and the disease progression rate was 68.1% (32/47). Among all these patients, 31.9% (15/47) of patients had immune rejection; the median survival time was 6.5 (0.3–48) months, and the fatality rate was 61.7% (29/47). Considering that the therapeutic effect of ICIs in LT recipients with HCC recurrence or de novo carcinoma is not ideal, ICI treatment should be carefully considered for LT patients, and further research is needed.

Utilization of Immunotherapy for the Treatment of Hepatocellular Carcinoma in the Peri-Transplant Setting: Transplant Oncology View

Simple Summary

Hepatocellular carcinoma is the second most common cause of cancer-related deaths and accounts for over eighty percent of primary liver cancers worldwide. Regarding the Milan Criteria, only a small portion of HCC patients are eligible for liver transplantation due to advanced-stage disease and large tumor size preventing/delaying organ allocation. Recently, the use of anti-programmed cell death protein 1 and programmed cell death ligand 1 (PD-1 and PD-L1) checkpoint inhibitors in the treatment of cancers have evolved rapidly and these therapies have been approved for the treatment of HCC, however, the main concerns about organ rejection in liver transplant patients who will be treated with ICPIs are still the same in both pre-and post-transplant setting. To alleviate those concerns, more global collaborations to explore the safety and efficacy of ICPIs in both the pre-and post-organ transplantation settings are required. The decision to administer ICPI treatment in liver transplant patients should be made on a case-by-case basis according to the goal of care and the availability and efficacy of other treatment options.

Abstract

Hepatocellular carcinoma (HCC) represents the second most common cause of cancer-related deaths and accounts for over eighty percent of primary liver cancers worldwide. Surgical resection and radiofrequency ablation in small tumors are included in the treatment options for HCC patients with good liver function profiles. According to the Milan Criteria, only a small portion of HCC patients are eligible for liver transplantation due to advanced-stage disease and large tumor size preventing/delaying organ allocation. Recently, the use of anti-programmed cell death protein 1 and programmed cell death ligand 1 (PD-1 and PD-L1) checkpoint inhibitors in the treatment of cancers have evolved rapidly and these therapies have been approved for the treatment of HCC. Immune checkpoint inhibitors have resulted in good clinical outcomes in pre-and post-transplant HCC patients, although, some reports showed that certain recipients may face rejection and graft loss. In this review, we aim to illustrate and summarize the utilization of immune checkpoint inhibitor therapies in pre-and post-liver transplants for HCC patients and discuss the assessment of immune checkpoint inhibitor regulators that might determine liver transplant outcomes.

Immunotherapy in liver transplantation for hepatocellular carcinoma: Pros and cons

Liver transplantation (LT) has emerged as a curative strategy for hepatocellular carcinoma (HCC), but contributes to a higher predisposition to HCC recurrence in the immunosuppression context, especially for tumors beyond the Milan criteria. Although immunotherapy has dramatically improved survival for immunocompetent patients and has become the standard of care for a variety of tumors, including HCC, it is mainly used outside the scope of organ transplantation owing to potentially fatal allograft rejection. Nevertheless, accumulative evidence has expanded the therapeutic paradigms of immunotherapy for HCC, from downstaging or bridging management in the pretransplant setting to the salvage or adjuvant strategy in the posttransplant setting. Generally, immunotherapy mainly includes immune checkpoint inhibitors (ICIs), adoptive cell transfer (ACT) and vaccine therapy. ICIs, followed by ACT, have been most investigated in LT, with some promising results. Because of the complex tumor microenvironment and immunoreactivity when immunosuppressants are combined with immunotherapy, it is difficult to reach formulations for immunosuppressant adjustment and the optimal selection of immunotherapy as well as patients. In addition, the absence of effective biomarkers for identifying rejection and tumor response is still an unresolved barrier to successful clinical immunotherapy applications for LT. In this review, we comprehensively summarize the available evidence of immunotherapy used in LT that is specific to HCC. Moreover, we discuss clinically concerning issues regarding the concurrent goals of graft protection and antitumor response.

Immunotherapy after liver transplantation: Where are we now?

BACKGROUND

There is limited evidence on the safety of immunotherapy use after liver transplantation and its efficacy in treating post-liver transplant hepatocellular carcinoma (HCC) recurrence.

AIM

To assess the safety of immunotherapy after liver transplant and its efficacy in treating post-liver transplant HCC recurrence.

METHODS

A literature review was performed to identify patients with prior liver transplantation and subsequent immunotherapy. We reviewed the rejection rate and risk factors of rejection. In patients treated for HCC, the oncological outcomes were evaluated including objective response rate, progression-free survival (PFS), and overall survival (OS).

RESULTS

We identified 25 patients from 16 publications and 3 patients from our institutional database (total n = 28). The rejection rate was 32% (n = 9). Early mortality occurred in 21% (n = 6) and was mostly related to acute rejection (18%, n = 5). Patients who developed acute rejection were given immunotherapy earlier after transplantation (median 2.9 years vs 5.3 years, P = 0.02) and their graft biopsies might be more frequently programmed death ligand-1-positive (100% vs 33%, P = 0.053). Their PFS (1.0 ± 0.1 mo vs 3.5 ± 1.1 mo, P = 0.02) and OS (1.0 ± 0.1 mo vs 19.2 ± 5.5 mo, P = 0.001) compared inferiorly to patients without rejection. Among the 19 patients treated for HCC, the rejection rate was 32% (n = 6) and the overall objective response rate was 11%. The median PFS and OS were 2.5 ± 1.0 mo and 7.3 ± 2.7 mo after immunotherapy.

CONCLUSION

Rejection risk is the major obstacle to immunotherapy use in liver transplant recipients. Further studies on the potential risk factors of rejection are warranted.

[The use of immuno-oncologic therapy in hepatocellular carcinoma in the context of liver transplantation. An interdisciplinary benefit/risk assessment]

BACKGROUND

Multiple systemic therapy options have been recently approved for the treatment of hepatocellular carcinoma (HCC). In particular, immuno-oncology combination therapies can now achieve impressive response rates and significantly prolonged survival with good tolerability. These immuno-oncology (IO)-based combinations are currently not only evaluated for the therapy of advanced HCC, but increasingly also in earlier stages in terms of peri-interventional therapy concepts and also for down-sizing to local therapies. In the context of liver transplantation (LTx), a particularly critical benefit/risk assessment must be made before the use of immunotherapeutics in the context of multimodal concepts, since the risk of a potentially lethal rejection can be significantly increased by immunotherapy.

METHODS

This review is based on a selective literature search performed between December 2020 and April 2021 in the PubMed and Cochrane Library databases. Guidelines, expert opinions, and recommendations from professional societies were given special consideration.

RESULTS

Nearly one in five LTx in Germany are performed due to HCCs. In this context, LTx is a curative therapy option not only for the underlying liver disease but also for the malignant tumor. Individual case reports indicate that IO therapy prior to LTx may increase the risk of rejection or liver failure after subsequent liver transplantation. Since 2015, immunotherapeutics have also been widely used for tumor therapy in patients after LTx. In small case series, rejection rates of 36%, associated with rejection-related mortality of 20% of treated patients, have been described. A similar incidence of rejection has also been described following the use of immunotherapeutics in patients after other organ transplantations.

CONCLUSION

In the context of organ transplantation, IO therapy carries the risk of graft rejection, which can lead to graft loss and also patient death. However, from today's point of view, IO-based therapy can be considered in the context of organ transplantation with a careful benefit/risk assessment.

Transplant Oncology: An Evolving Field in Cancer Care

Transplant oncology is an emerging concept of cancer treatment with a promising prospective outcome. The application of oncology, transplant medicine, and surgery to improve patients' survival and quality of life is the core of transplant oncology. Hepatobiliary malignancies have been treated by liver transplantation (LT) with significant improved outcome. In addition, as the liver is the most common site of metastasis for colorectal cancer (CRC), patients with CRC who have stable unresectable liver metastases are good candidates for LT, and initial studies have shown improved survival compared to palliative systemic therapy. The indications of LT for hepatobiliary malignancies have been slowly expanded over the years in a stepwise manner; however, they have only been shown to improve patient survival in the setting of limited systemic therapy options. This review illustrates the concept and history of transplant oncology as an evolving field for the management of hepatocellular carcinoma, intrahepatic biliary cancer, and liver-only metastasis of non-hepatobiliary carcinoma. The utility of immunotherapy in the transplant setting is discussed as well as the feasibility of using circulating tumor DNA for surveillance post-transplantation.

Argentinian clinical practice guideline for surveillance, diagnosis, staging and treatment of hepatocellular carcinoma

The A.A.E.E.H has developed this guideline for the best care of patients with hepatocellular carcinoma (HCC) from Argentina. It was done from May 2018 to March 2020. Specific clinical research questions were systematically searched. The quality of evidence and level of recommendations were organized according to GRADE. HCC surveillance is strongly recommended with abdominal ultrasound (US) every six months in the population at risk for HCC (cirrhosis, hepatitis B or hepatitis C); it is suggested to add alpha-feto protein (AFP) levels in case of inexeperienced sonographers. Imaging diagnosis in patients at risk for HCC has high specificity and tumor biopsy is not mandatory. The Barcelona Clinic Liver Cancer algorithm is strongly recommended for HCC staging and treatment-decision processes. Liver resection is strongly recommended for patients without portal hypertension and preserved liver function. Composite models are suggested for liver transplant selection criteria. Therapies for HCC with robust clinical evidence include transarterial chemoembolization (TACE) and first to second line systemic treatment options (sorafenib, lenvatinib, regorafenib, cabozantinib and ramucirumab). Immunotherapy with nivolumab and pembrolizumab has failed to show statistical benefit but the novel combination of atezolizumab plus bevacizumab has recently shown survival benefit over sorafenib in frontline.

Neoadjuvant Programmed Cell Death 1 (PD-1) Inhibitor Treatment in Patients With Hepatocellular Carcinoma Before Liver Transplant: A Cohort Study and Literature Review

Programmed cell death 1 (PD-1) blockade is considered contraindicated in liver transplant (LT) recipients due to potentially lethal consequences of graft rejection and loss. Though post-transplant PD-1 blockade had already been reported, pre-transplant use of PD-1 blockade has not been thoroughly investigated. This study explores the safety and efficacy of neoadjuvant PD-1 blockade in patients with hepatocellular carcinoma (HCC) after registration on the waiting list. Seven transplant recipients who underwent neoadjuvant PD-1 blockade combined with lenvatinib and subsequent LT were evaluated. The objective response rate (ORR) and disease control rate (DCR) was 71% and 85% according to the mRECIST criteria. Additionally, a literature review contained 29 patients were conducted to summarize the PD-1 blockade in LT for HCC. Twenty-two LT recipients used PD-1 inhibitors for recurrent HCC. 9.1% (2/22) and 4.5% (1/22) recipients achieved complete remission (CR) and partial remission (PR), respectively; 40.9% (9/22) recipients had progressive disease (PD). Allograft rejection occurred in 45% of patients. In total, seven patients from our center and three from the literature used pretransplant anti-PD-1 antibodies, eight patients (80%) had a PR, and the disease control rate was 100%. Biopsy-proven acute rejection (BPAR) incidence was 30% (3 in 10 patients), two patients died because of BPAR. This indicated that neoadjuvant PD-1-targeted immunotherapy plus tyrosine kinase inhibitors (TKI) exhibited promising efficacy with tolerable mortality in transplant recipients under close clinical monitoring.

Application of Immune Checkpoint Inhibitors in Solid Organ Transplantation Recipients: A Systematic Review

BACKGROUND

Solid organ transplantation (SOT) is a treatment method for end-stage organ diseases and improve their life quality, while using long-term immunosuppressant drugs (ISD) is needed to suppress the function of the immune system. Immune checkpoint inhibitors (ICIs) are a class of anti-tumor drugs that kill tumors by activating the autoimmune system. The primary objective of our systematic review is to investigate the risk factors for organ rejection and the efficacy of ICIs in solid organ transplantation recipients (SOTRs).

METHODS

We searched four databases to find relevant articles up to January 2021. A total of 61 articles involving 106 SOTRs met the screening criteria and were included in our systematic review. The collected data were statistical described, and the risk factors were analyzed by logistic regression.

RESULTS

Forty-four patients (41.5%) developed host-versus-graft response (HVGR) after ICIs. mTOR inhibitors (pre-ICIs) (p = 0.069, OR = 0.377, 95% CI 0.132-1.078) and calcineurin inhibitors (post-ICIs) (p = 0.056, OR = 0.375, 95%CI 0.137-1.025) may help reduce the incidence of HVGR. Hormones (pre-ICIs) (p = 0.026, OR = 3.150, 95%CI 1.150-8.628) and anti-metabolites (pre-ICIs) (p = 0.022, OR = 3.214, 95%CI 1.185-8.720) may adversely affect the efficacy of ICIs. Only 35.6% of patients both responded well to ICIs treatment and did not develop HVGR.

CONCLUSIONS

Our systematic review summarizes the use of ICIs in SOTRs and evaluates the efficacy of ICIs and the risk factors that induce HVGR. Through risk factor analysis, we found that mTOR inhibitors and calcineurin inhibitors may help to reduce the occurrence of HVGR; hormones and anti-metabolic drugs may have adverse effects on the efficacy of ICIs. In addition, there is a contradictory relationship between the occurrence of HVGR and the efficacy of ICIs.

The Role of Immunotherapy in Hepatocellular Carcinoma: A Systematic Review and Pooled Analysis of 2,402 Patients

BACKGROUND

Immune checkpoints inhibitors (ICIs) have emerged as a treatment option for several malignancies. Nivolumab, pembrolizumab, nivolumab plus ipilimumab, and atezolizumab plus bevacizumab have been approved for the management of advanced-stage hepatocellular carcinoma (HCC). We aimed to systematically review the literature and summarize the characteristics and outcomes of patients with HCC treated with ICIs.

METHODS

A systematic literature search of PubMed, the Cochrane Library, and ClinicalTrials.gov was performed according to the PRISMA statement (end of search date: November 7, 2020). Quality of evidence assessment was also performed.

RESULTS

Sixty-three articles including 2,402 patients were analyzed, 2,376 of whom received ICIs for unresectable HCC. Response to ICIs could be evaluated in 2,116 patients; the overall objective response rate (ORR) and disease control rate (DCR) were 22.7% and 60.7%, respectively, and the mean overall survival (OS) was 15.8 months. The ORR, DCR, and OS for nivolumab (n = 846) were 19.7%, 51.1%, and 18.7 months, respectively; for pembrolizumab (n = 435) they were 20.7%, 64.6% and 13.3 months, respectively. The combination of atezolizumab/bevacizumab (n = 460) demonstrated an ORR and DCR of 30% and 77%, respectively. The overall rate of treatment discontinuation because of adverse events was 14.9%. Fifteen patients received ICIs in the liver transplant (LT) setting (one pre-LT for bridging, 14 for post-LT recurrence); fatal graft rejection was reported in 40.0% (n = 6/15) and mortality in 80.0% (n = 12/15).

CONCLUSION

ICIs are safe and effective against unresectable HCC, but caution is warranted regarding their use in the LT setting because of the high graft rejection rate.

IMPLICATIONS FOR PRACTICE

This systematic review pooled the outcomes from studies reporting on the use of immune checkpoint inhibitors (ICIs) for the management of 2,402 patients with advanced-stage hepatocellular carcinoma (HCC), 2,376 of whom had unresectable HCC. The objective response rate and disease control rate were 22.7% and 60.7%, respectively, and the mean overall survival was 15.8 months. The overall rate of treatment discontinuation because of adverse events was 14.9%. Fifteen patients received ICIs in the liver transplant (LT) setting (one pre-LT for bridging, 14 for post-LT recurrence). Six of these patients experienced graft rejection (40.0%).

Immune Checkpoint Inhibitors in Transplantation-A Case Series and Comprehensive Review of Current Knowledge

Cancer is a leading cause of morbidity and deaths in solid organ transplant recipients. In immunocompetent patients, cancer prognosis has been dramatically improved with the development of immune checkpoint inhibitors (ICI), as programmed cell death protein 1/programmed death-ligand 1 and cytotoxic T lymphocyte-associated antigen 4 inhibitors, that increase antitumor immune responses. ICI has been developed outside of the scope of transplantation because of the theoretical risk of graft rejection, which has later been confirmed by the publication of several cases and small series. The use of ICI became unavoidable for treating advanced cancers including in organ transplant patients, but their management in this setting remains highly challenging, as to date no strategy to adapt the immunosuppression and to prevent graft rejection has been defined. In this article, we report a monocentric series of 5 solid organ transplant recipients treated with ICI and provide a comprehensive review of current knowledge of ICI management in the setting of solid organ transplantation. Strategies warranted to increase knowledge through collecting more exhaustive data are also discussed.

Anti-Programmed Cell Death Protein 1 (PD-1) Immunotherapy for Metastatic Hepatocellular Carcinoma After Liver Transplantation: A Report of Three Cases

The treatment of recurrent hepatocellular carcinoma (HCC) after liver transplantation is difficult due to the lack of effective treatment options. The available evidence on the emerging immunotherapy in liver transplantation is based on anecdotal experiences and requires additional investigations. To determine the efficacy and safety of immunotherapy in liver transplant recipients, we report three cases of recurrent metastatic HCC after liver transplantation who were treated with nivolumab as off-label salvage therapy.

Liver toxicity as a limiting factor to the increasing use of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) improve clinical outcomes in patients suffering from different types of cancer. Liver toxicity is one of the immune-related adverse events associated with immunotherapy; although not common, its management is challenging as it is extremely heterogeneous in terms of presentation and severity. Differences in the development and evolution of ICI-related toxicity in healthy or cirrhotic livers have not yet been elucidated. Assessing causality is key to diagnosing ICI-induced liver toxicity; liver biopsies can assist not only in the differential diagnosis but also in assessing the severity of histological liver damage. The current classification of severity overestimates the grade of liver injury and needs to be revised to reflect the views of hepatologists. Spontaneous improvements in ICI-related liver toxicity have been reported, so corticosteroid therapy should probably be individualised not systematic. The reintroduction of ICIs in a patient with previous immune-mediated hepatitis may be possible, but the risk/benefit ratio should be considered, as the risk factors for hepatitis recurrence are currently unclear. The management of these patients, requiring a balance between efficacy, toxicity and specific treatments, necessitates multidisciplinary collaboration. The incidence of immune-related liver toxicity will continue to rise based on the increasing use of ICIs for most cancers, mandating improved understanding and management of this complication.

Immune Checkpoint Inhibitors in Patients with Recurrent Hepatocellular Carcinoma after Liver Transplantation: A Case Report and Literature Review

BACKGROUND

Immune checkpoint modulators, such as the programmed death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibitor, cytotoxic T-Lymphocyte-associated antigen 4 (CTLA-4) inhibitor have been investigated with encouraging results for hepatocellular carcinoma (HCC). However, the safety of this strategy in patients with previous liver transplantation (LT) is not well studied.

OBJECTIVE

To explore the safety and feasibility of immune checkpoints inhibitors in recurrent and metastatic HCC patients on a background of LT.

METHODS

A case of recurrent, refractory, metastatic HCC after LT, where PD-1 inhibitor was initiated, was described and related literature was reviewed.

RESULTS

There was complete remission in lung metastases and the partial radiological response of metastatic retroperitoneal lymph node to the drug with no liver graft rejection after 13 cycles of PD- 1 inhibitor injection. PD-1inhibitor, at least in this patient, was verified to play an important role in controlling tumor progression and prolonging patient survival.

CONCLUSION

This novel drug might be a useful method to allow doctors to guarantee a better chance for long-term survival in recurrent, metastatic HCC patients with the previous LT. However, it should be used with caution in allograft recipients due to the risk of acute graft rejection, further larger, prospective studies are needed to determine optimal immunomodulatory therapy to achieve optimal anti-tumor efficacy with transplant liver preservation.

Annexin A2 promotion of hepatocellular carcinoma tumorigenesis via the immune microenvironment

Hepatocellular carcinoma (HCC) is the most common primary liver cancer with a dismal prognosis, especially when diagnosed at advanced stages. Annexin A2 (ANXA2), is found to promote cancer progression and therapeutic resistance. However, the underlining mechanisms of ANXA2 in immune escape of HCC remain poorly understood up to now. Herein, we summarized the molecular function of ANXA2 in HCC and its relationship with prognosis. Furthermore, we tentatively elucidated the underlying mechanism of ANXA2 immune escape of HCC by upregulating the proportion of regulatory T cells and the expression of several inhibitory molecules, and by downregulating the proportion of natural killer cells and dendritic cells and the expression of several inhibitory molecules or effector molecules. We expect a lot of in-depth studies to further reveal the underlying mechanism of ANXA2 in immune escape of HCC in the future.

Cutaneous squamous cell carcinoma in the organ transplant recipient

One in twenty solid organ transplant recipients (SOTRs) will develop a highly morbid or fatal cutaneous carcinoma after transplantation. The majority of these cases develop on the head and neck and may require intervention on the part of dermatology, dermatologic surgery, otolaryngology, transplant medicine, radiation oncology, and medical oncology. In this review, we discuss the problem of cutaneous squamous cell carcinoma (cSCC) in SOTRs as well as the prognostic factors and management strategies to care for this population.

Fatal hepatic necrosis after nivolumab as a bridge to liver transplant for HCC: Are checkpoint inhibitors safe for the pretransplant patient?

Nivolumab is an immune checkpoint inhibitor (ICI) currently in phase 3 clinical trials for hepatocellular carcinoma. The safety of ICIs in recipients of organ allotransplant is unclear, and several reports of fatal alloimmune injury after posttransplant ICI use have been published. We present the first published case of nivolumab used in the pretransplant setting for HCC resulting in fatal acute hepatic necrosis in the immediate postoperative period from a profound immune reaction likely propagated by nivolumab. Further investigation and significant caution are needed in the evaluation of patients awaiting transplant who are receiving ICI therapy.

The Safety and Efficacy of Checkpoint Inhibitors in Transplant Recipients: A Case Series and Systematic Review of Literature

Limited data exist on safety and efficacy of immune checkpoint inhibitors (ICIs) among organ transplant recipients. The objective of this study was to report a case series of two patients with renal transplant who received treatment with an ICI and to conduct a pooled analysis of published cases to describe the safety and efficacy of ICIs in organ transplant patients. A systematic search in the Google Scholar and PubMed databases was carried out to include all the published cases of organ transplant patients who received treatment with ICIs including programmed cell death protein 1 (PD-1), programmed death-ligand 1, or cytotoxic lymphocyte antigen-4 inhibitors since their inscription to January 31, 2019. In the present series of two cases with renal allografts who received pembrolizumab, one patient with squamous cell carcinoma of the skin experienced complete response (CR), whereas another patient with melanoma had a mixed response. Both patients experienced allograft rejection, but graft was salvaged. The pooled analysis of 64 patients published in literature showed that overall allograft rejection rate is 41% in organ transplant recipients following ICI therapy. The graft rejection rate was 44% (17/39) for renal, 39% (7/19) for liver, and 20% (1/5) for cardiac allografts. The highest risk was seen among patients who were treated with PD-1 inhibitors, 20/42 (48%)-13/24 (54%) on nivolumab and 7/18 (39%) on pembrolizumab. The risk was lowest with ipilimumab, 23% (3/13). The overall response rate (CR + partial response [PR]) was 20% with ipilimumab, 26% with nivolumab, and 53% with pembrolizumab, whereas disease control rate (CR + PR + stable disease) was 35% with ipilimumab, 37% with nivolumab, and 53% with pembrolizumab. None of the variables including age, gender, type of cancer, type of allograft, type of immunosuppression, time since transplantation to initiation of ICI, and prior history of rejection were significantly associated with the transplant rejection on univariate analysis. The efficacy of ICI among patients with organ transplant appears promising, warranting testing in prospective clinical trials. The risk of rejection and allograft loss is considerable; therefore, the risk and alternative form of therapies should be thoroughly discussed with the transplant patients prior to initiating ICI therapy. IMPLICATIONS FOR PRACTICE: Transplant recipients are at higher risk of developing cancers. Although immune checkpoint inhibitors have been shown to improve the outcome in more than one cancer type, transplant recipients were excluded from these trials. Most of the data on the safety and efficacy of immune checkpoint inhibitors in transplant patients are based upon case series and case reports. The pooled data from these reports suggest that anti-programmed death-ligand 1 inhibitors have reasonable safety and efficacy among organ transplant patients, which warrants testing in clinical trials.

Liver graft rejection following immune checkpoint inhibitors treatment: a review

Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in a variety of solid tumors; nonetheless, they have not been well investigated and are still recognized as a relative contraindication for patients with a liver transplantation (LT) history, since ICIs treatment might potentially lead to graft rejection. The program death-1 (PD-1) and the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) pathways are implicated in the tolerance of transplanted organ, as well as blockade of the pathways, which contribute to eliminating tumors and may inadvertently lead to peripheral transplant rejection. Currently, no guidelines are available regarding the treatment for ICIs patients with a prior LT history. Therefore, this study was carried out to review the recent studies, attempting to introduce the ICIs-related graft rejection after LT from various aspects. We believed that ICIs could be given for the well-informed patients receiving LT and developed recurrence in a controlled setting. Typically, these patients should be treated according to a clinical care path or a prospective clinical trial, so as obtain a persistent anti-tumor immune response in the meantime of avoiding graft rejection, adjust the immunosuppression, reduce the possibility of graft loss following rejection, and have the opportunity to develop biomarkers for tumor response and transplant rejection.

New Systemic Treatments in Advanced Hepatocellular Carcinoma

The principal advancements in the treatment of hepatocellular carcinoma (HCC) are the use of new systemic treatments, such as lenvatinib in first-line treatment and regorafenib, cabozantinib, and ramucirumab in second-line treatment, because of their benefits in terms of overall survival. In addition, nivolumab as a second-line agent was approved by the US Food and Drug Administration in 2017 based on improved radiological response data. Physicians and patients alike will greatly benefit from this expanded arsenal of treatments once all these new drugs for the treatment of HCC finally become available. Unfortunately, in our review of the available data, we found a conspicuous lack of approved systemic treatments for HCC in the distinct setting of after liver transplantation (LT). Careful evaluation of the clinical trials for approved systemic treatments of HCC is crucial when considering the best options for those with HCC recurrence after LT. Although several first-line or second-line treatments have been shown to be effective for HCC, each of these trials was composed of its own specific populations, and those with HCC recurrence after LT were excluded. We have also summarized from a critical and clinical point of view the issues involved in the management of patients who are candidates for systemic treatment in this era of multiple drugs for the same indication.

Pilot evaluation of PD-1 inhibition in metastatic cancer patients with a history of liver transplantation: the Mayo Clinic experience

Background

Patients with solid organ transplants (SOTs) have been excluded from programmed death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibitor clinical trials due to concern for allograft rejection. The use of immune checkpoint inhibitor therapy remains controversial in transplant patients.

Methods

A retrospective pilot evaluation was conducted to assess the safety and efficacy of PD-1 inhibitors in patients with liver transplantation (LT). The primary endpoint was the rate of allograft rejection. Secondary endpoints included overall response rate (ORR), progression free survival (PFS) and overall survival (OS). Translational objectives included evaluation of tumor PD-L1, tumor infiltrating lymphocytes (TILs) and allograft PD-L1 expression.

Results

Seven metastatic cancer patients with a history of LT who received PD-1 inhibitor therapy were included [hepatocellular carcinoma (HCC), n=5; melanoma, n=2]. Rejection was observed in 2 of 7 patients. When rejection occurs it appears to be an early event with a median time to rejection of 24 days in our cohort. One patient achieved a complete response (CR), 3 patients had progressive disease (PD) and 3 patients discontinued therapy prior to restaging assessments. Two of five patients with available tissue had PD-L1 expression in the allograft and both developed rejection. One of five evaluable patients had abundant TILs. Two of five evaluable patients had PD-L1 tumor staining. The single patient with both abundant TILs and PD-L1 staining obtained a response. The median OS and PFS were 1.1 (0.3-21.1) and 1.8 (0.7-21.1) months, respectively.

Conclusions

In this pilot evaluation both preliminary efficacy (1 of 4) and allograft rejection (2 of 7) were exhibited in evaluable patients. Larger, prospective trials are needed to elucidate optimal patient selection.

Review article: systemic treatment of hepatocellular carcinoma

BACKGROUND

The approval of the tyrosine kinase inhibitor sorafenib in 2007 marked a milestone in the treatment of hepatocellular carcinoma, as sorafenib was the first systemic therapy to show a survival benefit in patients with advanced hepatocellular carcinoma. Since then many drugs failed in the first- and second-line setting and it took almost another decade until further tyrosine kinase inhibitors succeeded in phase III trials.

AIM

To summarise the evolving field of systemic therapy of hepatocellular carcinoma.

METHODS

We reviewed recently published studies identified from PubMed and data presented at recent meetings. Main search terms included hepatocellular carcinoma, tyrosine kinase inhibitors, immunotherapy, immune checkpoint inhibitors, sorafenib, regorafenib, lenvatinib, cabozantinib, ramucirumab, and nivolumab.

RESULTS

We discuss the evolution of targeted therapies since the approval of sorafenib including failures and recent advances. We also elaborate the unmet need of biomarkers to guide treatment decisions and discuss the emerging field of immunotherapy in hepatocellular carcinoma.

CONCLUSIONS

The tyrosine kinase inhibitors sorafenib (first line) and regorafenib (second line) have been approved for hepatocellular carcinoma, and the immune checkpoint inhibitor nivolumab obtained conditional approval for sorafenib-experienced patients in the United States. With lenvatinib in the first line, and cabozantinib and ramucirumab in sorafenib-experienced patients, three more targeted therapies reached their primary endpoint in phase III trials and may soon be added to the treatment armamentarium.