Mammalian target of rapamycin inhibitors after post-transplant hepatocellular carcinoma recurrence: Is it too late?

Sirolimus vs tacrolimus: Which one is the best therapeutic option for patients undergoing liver transplantation for hepatocellular carcinoma?

Liver transplantation (LT) withstands as the most preferred therapeutic option for patients afflicted with hepatocellular carcinoma (HCC) and cirrhosis. To improve prognosis post-transplant, as well as to prevent the occurrence of rejection, a life-long immunosuppression strategy is implemented. The following letter to the editor highlights and provides novel evidence from recently published literature on topics discussed within the review article titled “Trends of rapamycin in survival benefits of liver transplantation for hepatocellular carcinoma” in World J Gastrointest Surg 2021; 13: 953-966. In the recent manuscript, the authors compared immunosuppressive drugs such as the newer option first-generation mammalian target of rapamycin inhibitor, also known as sirolimus, with the most widely used first-generation calcineurin inhibitors, such as tacrolimus (TAC). TAC is commonly known as the most effective immunosuppressive drug after LT, but it has been reported to cause intolerable side effects such as nephrotoxicity, neurotoxicity, diabetes, hypertension, gastrointestinal disturbances, increased risk of infections, and malignancies. It is necessary for physicians to be aware of recent advances in tacrolimus and sirolimus therapies to compare and understand distinctly the effectiveness and tolerability of these drugs. This will assist clinicians in making the best treatment decisions and improve the clinical prognosis of LT recipients with HCC.

Impact of Tumour Biology on Outcomes of Radical Therapy for Hepatocellular Carcinoma Oligo-Recurrence after Liver Transplantation

It is uncertain whether tumour biology affects radical treatment for post-transplant hepatocellular carcinoma (HCC) oligo-recurrence, i.e. recurrence limited in numbers and locations amendable to radical therapy. We conducted a retrospective study on 144 patients with post-transplant HCC recurrence. Early recurrence within one year after transplant (HR 2.53, 95% CI 1.65−3.88, p < 0.001), liver recurrence (HR 1.74, 95% CI 1.12−2.68, p = 0.01) and AFP > 200 ng/mL upon recurrence (HR 1.62, 95% CI 1.04−2.52, p = 0.03) predicted mortality following recurrence. In patients with early recurrence and liver recurrence, radical treatment was associated with improved post-recurrence survival (early recurrence: median 18.2 ± 1.5 vs. 9.2 ± 1.5 months, p < 0.001; liver recurrence: median 28.0 ± 4.5 vs. 11.6 ± 2.0, p < 0.001). In patients with AFP > 200 ng/mL, improvement in survival did not reach statistical significance (median 18.2 ± 6.5 vs. 8.8 ± 2.2 months, p = 0.13). Survival benefits associated with radical therapy were reduced in early recurrence (13.6 vs. 9.0 months) and recurrence with high AFP (15.4 vs. 9.3 months) but were similar among patients with and without liver recurrence (16.9 vs. 16.4 months). They were also diminished in patients with multiple biological risk factors (0 risk factor: 29.0 months; 1 risk factor: 19.7 months; 2−3 risk factors: 3.4 months): The survival benefit following radical therapy was superior in patients with favourable biological recurrence but was also observed in patients with poor tumour biology. Treatment decisions should be individualised considering the oncological benefits, quality of life gain and procedural morbidity.

Sirolimus or Everolimus Improves Survival After Liver Transplantation for Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

The effects of mammalian target of rapamycin (mTOR) inhibitors (sirolimus [SRL] and everolimus [EVL]) on survival in liver transplantation (LT) recipients with hepatocellular carcinoma (HCC) remain the subject of intense research. Therefore, we performed this systematic review and meta-analysis to investigate the potential survival benefits of mTOR inhibitors (mTORis). Embase, PubMed, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for all randomized controlled trials (RCTs) and cohort studies investigating effects of SRL or EVL on LT recipients for HCC. The primary outcomes were 1-, 2-, 3-, and 5-year overall survival (OS), and the secondary outcomes were 1-, 2-, and 3-year recurrence-free survival (RFS) and adverse effects. Pooled relative risks (RRs) with 95% confidence interval (CI) were calculated by a fixed or random effects model with Mantel-Haenszel weighting. Subgroup analyses were performed according to crucial clinical characteristics. We also conducted sensitivity analyses to assess the reliability of our findings. A total of 17 studies were included. OS was improved in both RCTs (1 year: RR, 1.04; 95% CI, 1.00-1.08; 2 years: RR, 1.09; 95% CI, 1.02-1.16; 3 years: RR, 1.13; 95% CI, 1.04-1.24; 5 years: RR, 1.13; 95% CI, 1.02-1.26) and cohort studies (1 year: RR, 1.13; 95% CI, 1.06-1.20; 2 years: RR, 1.24; 95% CI, 1.16-1.32; 3 years: RR, 1.24; 95% CI, 1.15-1.34; 5 years: RR, 1.17; 95% CI, 1.10-1.24), with a lower risk of renal toxicity (RR, 0.75; 95% CI, 0.60 to 0.93). The 1-, 2-, and 3-year RFS were also improved. Current evidence indicates that SRL- or EVL-based immunosuppression improves OS and RFS with a lower risk of renal toxicity compared with mTORi-free immunosuppression. Nevertheless, results must be interpreted with caution.

Verifying the Benefits of Radical Treatment in Posttransplant Hepatocellular Carcinoma Oligo-recurrence: A Propensity Score Analysis

This study verified whether radical treatment for hepatocellular carcinoma (HCC) oligo-recurrence after liver transplantation conveys survival benefits. A retrospective study of 144 patients with posttransplant HCC recurrence was performed. Propensity score matching was performed to adjust for baseline covariates between patients who received radical and palliative treatments. The primary endpoint was postrecurrence survival. A total of 50 patients (35%) received radical treatment for recurrence, and 76 (53%) and 18 (13%) patients received palliative and supportive treatments, respectively. Compared with the radical group, patients who received palliative treatment had more early recurrences (time from transplant 17 versus 11 months; P = 0.01) and more extensive disease in terms of tumor numbers (1 versus 4; P < 0.001), size of largest tumor (1.8 versus 2.5 cm; P = 0.046), numbers of involved organs (interquartile range [IQR], 1-1 versus 1-2; P = 0.02), and alpha-fetoprotein (AFP) level (7 versus 40 ng/mL; P = 0.01). Multivariate Cox regression analysis revealed that early recurrence (time from transplant hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.01-1.03; P = 0.001), larger recurrent tumor (HR, 1.12; 95% CI, 1.03-1.23; P = 0.01), liver recurrence (HR, 1.84; 95% CI, 1.17-2.90; P = 0.01), and log₁₀ AFP level at recurrence (HR, 1.27; 95% CI, 1.07-1.52; P = 0.01) predicted poor survival. Mammalian target of rapamycin inhibitor (HR, 0.331; 95% CI, 0.213-0.548; P < 0.001) and radical treatment (HR, 0.342; 95% CI, 0.213-0.548; P < 0.001) were associated with improved survival. After 2-to-1 propensity score matching for covariates, the 50 patients who received curative treatment survived significantly longer than the 25 matched patients who received palliative treatment (median survival time, 30.9 ± 2.4 versus 19.5 ± 3.0 months; P = 0.01). Radical treatment conveys survival benefits to HCC oligo-recurrence after liver transplantation.

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 Importance of the Immunosuppressive Regime on Hepatocellular Carcinoma Recurrence After Liver Transplantation

PURPOSE

Hepatocellular carcinoma (HCC) recurrence after liver transplantation (LT) occurs in approximately 20% of recipients and these patients have median about one year survival after diagnosis. Some immunosuppressive drugs can cause development of HCC recurrence, on the other hand some immunosuppressive drugs may have a positive effect for preventing HCC recurrence. Thus, immunosuppression (IS) modification may play a role in preventing HCC recurrence.

METHODS

In this review, we analyzed IS treatment strategy in two parts: before HCC recurrence following LT and after HCC recurrence following LT, and after HCC recurrence following LT.

RESULTS

There is no proven, optimal IS protocol to prevent HCC recurrence after transplantation. Therefore, individualized immunosuppressive treatments should be tailored to the biological behaviour of HCC. Forcing the immune tolerance in terms of recurrence can probably be expressed as the most appropriate post LT period. Once HCC recurrence has developed after transplantation, again, there is no commonly accepted, optimal IS treatment, but there is a tendency to switch to IS modifications that include mTORi by minimizing CNIs and MMF.

CONCLUSION

There is a need for well-designed, randomized, controlled clinical studies with larger numbers of patients on this subject.

THE MANAGEMENT OF POST-TRANSPLANTATION RECURRENCE OF HEPATOCELLULAR CARCINOMA

The annual incidence of hepatocellular carcinoma (HCC) continues to rise. Over the last two decades, liver transplantation (LT) has become the preferable treatment of HCC, when feasible and strict selection criteria are met. With the rise in HCC-related LT, compounded by downstaging techniques and expansion of transplant selection criteria, a parallel increase in number of post-transplantation HCC recurrence is expected. Additionally, in the context of an immunosuppressed transplant host, recurrences may behave aggressively and more challenging to manage, resulting in poor prognosis. Despite this, no consensus or best practice guidelines for post-transplantation cancer surveillance and recurrence management for HCC currently exist. Studies with adequate population sizes and high-level evidence are lacking, and the role of systemic and locoregional therapies for graft and extrahepatic recurrences remains under debate. This review seeks to summarize the existing literature on post-transplant HCC surveillance and recurrence management. It highlights the value of early tumour detection, re-evaluating the immunosuppression regimen, and staging to differentiate disseminated recurrence from intrahepatic or extrahepatic oligo-recurrence. This ultimately guides decision-making and maximizes treatment effect. Treatment recommendations specific to recurrence type are provided based on currently available locoregional and systemic therapies.

Performance of Dual-tracer PET-CT for Staging Post-Liver Transplant Hepatocellular Carcinoma Recurrence

Precise staging is essential in the management of patients with recurrent hepatocellular carcinoma (HCC) after liver transplantation. There is no current consensus on the optimal staging strategy. We conducted this study to evaluate the performance of dual-tracer positron emission tomography-computed tomography (PET-CT) for this purpose and to investigate whether the results of dual-tracer PET-CT affected patient management.

Methods

A retrospective study was conducted. Patients who underwent dual-tracer PET-CT for suspected or confirmed HCC recurrence after liver transplant were included. The lesion-based sensitivity and positive predictive value of dual-tracer PET-CT were determined.

Results

Fifty-six patients and 189 recurrent tumors were included. The lesion-based sensitivity and positive predictive value of dual-tracer PET-CT were 94.7% and 90.4%, respectively. The sensitivity of dual-tracer PET-CT was better than the standard imaging in the surveillance protocol (82.5% versus 94.7%, P < 0.001), especially for detecting liver recurrence (71.0% versus 96.8%, P < 0.001). Half of the dual-tracer PET-CT detected additional recurrence (n = 26, 46.4%) and one-third led to a change in management (n = 19, 33.9%). Ten patients (17.9%) with inconclusive standard imaging had metabolic recurrence confirmed on PET-CT and treatment was commenced early. Four patients (7.1%) had revised locoregional treatment, and 5 (8.9%) had to withdraw from locoregional treatment after the detection of additional metastatic disease.

Conclusions

Dual-tracer PET-CT is effective for staging posttransplant HCC recurrence. It often provides valuable information to guide clinical management.

Targeting molecular signal transduction pathways in hepatocellular carcinoma and its implications for cancer therapy

Hepatocellular carcinoma is a substantial health concern. It is currently the third dominating cause of mortality associated with cancer worldwide. The development of hepatocellular carcinoma is an intricate process that encompasses the impairment of genetic, epigenetic, and signal transduction mechanisms contributing to an aberrant metabolic system, enabling tumorigenesis. Throughout the past decade, research has led to the revelation of molecular pathways implicated in the progression of this notorious disorder. The altered signal transduction pathways, such as the mitogen-activated protein kinase pathway, phosphoinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway, WNT/β-catenin pathway, hepatocyte growth factor/c-MET pathway, and just another kinase/signal transducers and activators of transcription signaling pathway is of much therapeutic significance, as targeting them may avail to revert, retard or avert hepatocarcinogenesis. The present review article sums up the contemporary knowledge of such signaling mechanisms, including their therapeutic targets and betokens that novel and efficacious therapies can be developed only by the keen understanding of their character in hepatocarcinogenesis. In additament, we address the role of consequential therapeutic agents and preclinical nondrug therapies known for combating hepatocarcinogenesis.