Costimulatory blockade prevents early rejection, promotes lymphocyte apoptosis, and inhibits the upregulation of intragraft interleukin-6 in an orthotopic liver transplant model in the rat

Cell-Free DNA as a Surveillance Tool for Hepatocellular Carcinoma Patients after Liver Transplant

The liver is the world's sixth most common primary tumor site, responsible for approximately 5% of all cancers and over 8% of cancer-related deaths. Hepatocellular carcinoma (HCC) is the predominant type of liver cancer, accounting for approximately 75% of all primary liver tumors. A major therapeutic tool for this disease is liver transplantation. Two of the most significant issues in treating HCC are tumor recurrence and graft rejection. Currently, the detection and monitoring of HCC recurrence and graft rejection mainly consist of imaging methods, tissue biopsies, and alpha-fetoprotein (AFP) follow-up. However, they have limited accuracy and precision. One of the many possible components of cfDNA is circulating tumor DNA (ctDNA), which is cfDNA derived from tumor cells. Another important component in transplantation is donor-derived cfDNA (dd-cfDNA), derived from donor tissue. All the components of cfDNA can be analyzed in blood samples as liquid biopsies. These can play a role in determining prognosis, tumor recurrence, and graft rejection, assisting in an overall manner in clinical decision-making in the treatment of HCC.

The Synergistic Effect of Interventional Locoregional Treatments and Immunotherapy for the Treatment of Hepatocellular Carcinoma

Immunotherapy has remarkably revolutionized the management of advanced HCC and prompted clinical trials, with therapeutic agents being used to selectively target immune cells rather than cancer cells. Currently, there is great interest in the possibility of combining locoregional treatments with immunotherapy for HCC, as this combination is emerging as an effective and synergistic tool for enhancing immunity. On the one hand, immunotherapy could amplify and prolong the antitumoral immune response of locoregional treatments, improving patients' outcomes and reducing recurrence rates. On the other hand, locoregional therapies have been shown to positively alter the tumor immune microenvironment and could therefore enhance the efficacy of immunotherapy. Despite the encouraging results, many unanswered questions still remain, including which immunotherapy and locoregional treatment can guarantee the best survival and clinical outcomes; the most effective timing and sequence to obtain the most effective therapeutic response; and which biological and/or genetic biomarkers can be used to identify patients likely to benefit from this combined approach. Based on the current reported evidence and ongoing trials, the present review summarizes the current application of immunotherapy in combination with locoregional therapies for the treatment of HCC, and provides a critical evaluation of the current status and future directions.

Immunotherapy of Hepatocellular Carcinoma: Facts and Hopes

Treatment of patients with hepatocellular carcinoma (HCC) in the advanced stage remains a great challenge, with very few drugs approved. After decades of failure of immune therapies, immune checkpoint inhibitors have emerged as potentially effective treatments for patients with HCC in the advanced stage. Immune checkpoints, including human cancer, cytotoxic T-lymphocyte protein 4 (CTLA-4), and programmed cell death protein 1 (PD-1), are surface proteins expressed in a variety of immune cells and mostly provide immunosuppressive signals. Monoclonal antibodies able to block these molecules have shown antitumor activity against a wide spectrum of human cancers. Clinical experience with checkpoint inhibitors in HCC includes early trials with the anti-CTLA-4 agent tremelimumab and a large phase II trial with the anti-PD-1 agent nivolumab. The latter has shown strong activity particularly as second-line therapy, both in terms of tumor response and patient survival. At least three topics should be the focus of future research: (i) the search for activity in patients at less-advanced stages, including the adjuvant treatment of patients with resectable or ablatable tumors; (ii) the enhanced efficacy of combination therapies, including particularly the combination with those targeted and locoregional therapies that may have a synergistic effect or act upon mechanisms of primary or acquired resistance to checkpoint inhibitors; and (iii) the identification of clinical features and serum or tissue biomarkers that would allow a better patient selection for individual treatments. Hopefully, ongoing trials will help to design better treatments in the future. Clin Cancer Res; 24(7); 1518-24. ©2017 AACR.

Novel therapies in transplantation

Immunosuppressant drugs are crucial in order to protect transplanted kidney, heart or liver against the body's natural defence mechanisms. These drugs are used to prevent both acute rejection of the organ as well as chronic deterioration of the graft over longer periods of time. Currently used immunosuppressant drugs are calcineurin inhibitors (cyclosporin and tacrolimus), steroids (prednisolone and methylprednisolone), antimetabolites (azathioprine and mycophenolate mofetil), antiproliferatives (sirolimus) and monoclonal antibodies that are used as an induction therapy (basilximab, daclizumab and muromonab). Over time, we have learnt more about existing immunosuppressive choices and the ways to monitor these drugs, and the current trend in immunosuppression therapy is towards tailoring the therapy according to an individual patient. The major issue that is now emerging is not how to prevent acute rejection, as current drugs are all efficacious, but rather how to avoid the long-term side effects that can harm both the graft and host, and negatively influence compliance. The market in transplantation is considerable and still growing; the whole market including the immuno-suppressants used in autoimmune diseases had sales of approximately pound 1.5 billion in 2001. There are currently 23 new drugs in advanced clinical development intended to be used in either organ transplantation or as treatment of autoimmune diseases. The new drugs that are intended to be used in transplantation are mostly analogues of currently used drugs with improved safety and pharmaceutical profiles.

Intragraft gene and protein expression in rat liver allografts treated with costimulatory blockade alone or in combination with CyA

BACKGROUND

Costimulatory blockade has been shown to prevent acute rejection (AR) and promote long-term graft survival in a number of animal models including nonhuman primates. The effect of concomitant administration of conventional immunosuppressives on long-term liver allograft survival and intragraft expression of immune mediators has not previously been examined.

MATERIALS AND METHODS

A high-responding Dark Agouti to Lewis orthotopic liver transplant (LEW OLT) model was used to compare anti-CD154 alone, or in combination with cyclosporin (CyA) on allograft survival. Donor-specific reactivity was assessed by mixed lymphocyte reaction (MLR) and allogeneic skin grafts. Surviving rats were euthanized on day 150 and intragraft gene (CD80, 86, 152, 154, IFN-gamma, IL-2, IL-6, IL-10, IL-13, TNF-alpha, TGF-beta, IL-7, Fas-ligand, Granzyme B, bax, and bcl(2)) and protein (CD4, CD8, ED1, CD154, CD80, CD86) expression was measured.

RESULTS

Untreated control recipients had a median survival time of 5 days. Recipients treated with anti-CD154 survived to beyond 150 days with no evidence of AR. Concomitant administration of CyA did not alter the long-term survival. There was no difference in the serum aspartate aminotransferase between treatment groups or a change over time. All treated recipients showed a reduction in donor-specific MLR at day 40 and 60 but had persistence of donor reactivity to skin grafts at day 100. Histologically, liver architecture was well preserved despite the presence of a nondestructive mononuclear cell infiltrate. Analysis of intragraft gene expression revealed an inverse relationship between the duration of anti-CD154 therapy and the gene expression of costimulatory molecules and Th1 cytokine transcripts. The pro-apoptotic gene, bax, was increased in recipients treated with anti-CD154, but not CyA, compared with normal liver.

CONCLUSIONS

These data demonstrate that anti-CD154 therapy either alone or in combination with CyA allows for the long-term survival of liver allografts in the rat despite there being a difference in the intragraft gene and protein profile.

Analysis of intragraft gene and protein expression of the costimulatory molecules, CD80, CD86 and CD154, in orthotopic liver transplant recipients

CD40-CD154 and/or CD28-CD80/86 costimulatory blockade induces long-term allograft survival in numerous animal models. Studies examining the expression of costimulatory molecules during acute cellular rejection (ACR) have been limited to renal and cardiac allografts. The aim of this study was to describe the relationship between intragraft costimulatory molecule expression in OLT recipients and ACR. Forty-five liver biopsies were obtained at reperfusion and day 7. Gene and protein expression of CD80, CD86 and CD154 were analyzed by RT-PCR and immunohistochemistry. CD154 protein expression was present in 13 of 18 patients with a RAI score of 4, but in only two of 14 patients with a RAI score of <4. There was a strong association between the RAI score and the presence of CD80 and CD154 immunoreactivity. CD86 protein expression did not correlate with the severity of ACR. In reperfusion biopsies CD154, but not CD80 or CD86, protein expression correlated with the total ischaemic time. There was no association between expression of costimulatory molecule genes and ACR. In conclusion, we have demonstrated an association between CD154 and CD80 protein expression and ACR in orthotopic liver allografts.