The Key Role of Staging Definitions for Assessment of Downstaging for Hepatocellular Carcinoma

Optimal Liver Transplantation Criteria for Hepatocellular Carcinoma

Liver transplantation continues to be the optimal treatment for hepatocellular carcinoma (HCC). Given the limited organ supply, patient selection for liver transplant must carefully balance tumor progression with risk of recurrence posttransplant. There are several pretransplant selection criteria that incorporate biomarkers as well as imaging modality to risk-stratify patients as we continue to look for the optimal transplant cutoff for patients with HCC, which should be transplant-center specific, and account for organ availability and dynamic response to locoregional therapy.

Downstaging hepatocellular carcinoma before liver transplantation: A multicenter analysis of the "all-comers" protocol in the Multicenter Evaluation of Reduction in Tumor Size before Liver Transplantation (MERITS-LT) consortium

Patients with hepatocellular carcinoma meeting united network for organ sharing (UNOS)-downstaging (DS) criteria have excellent liver transplantation (LT) outcomes after DS. However, outcomes for "all-comers" (AC) patients with tumors initially exceeding UNOS-DS are poorly understood. Patients meeting AC (n = 82) or UNOS-DS (n = 229) at 7 LT centers in 4 UNOS regions were prospectively followed from 2015-2020. AC patients had a lower probability of successful DS (67% vs 83% within 12 months; P < .001). The 3-year survival was 69% for UNOS-DS vs 58% for AC (P = .05) and reduced to 30% in patients with Child-Pugh B/C cirrhosis or alpha-fetoprotein (AFP) ≥ 500. Five-year LT probability was 42% for AC vs 74% in UNOS-DS (P = .10). Thirty-eight percent were understaged on explant, with the increasing sum of the largest tumor diameter plus the number of lesions before LT (odds ratio 1.3; P = .01) and AFP ≥ 20 (odds ratio 5.9; P = .005) associated with understaging. Post-LT 3-year survival was 91% for AC vs 81% for UNOS-DS (P = .67). In this first prospective multiregional study of AC patients from the multicenter evaluation of reduction in tumor size before liver transplantation (MERITS-LT) consortium, we observed a 65% probability of successful DS. Three-year survival in AC was nearly 60%, though AC with Child-Pugh B/C or AFP ≥ 500 had poor survival. Explant pathology and 3-year post-LT outcomes were similar between cohorts, suggesting that LT is a reasonable goal in selected AC patients.

Hepatocellular carcinoma downstaging for liver transplantation in the era of systemic combined therapy with anti-VEGF/TKI and immunotherapy

Hepatocellular carcinoma remains a global health challenge affecting close to 1 million cases yearly. Liver transplantation provides the best long-term outcomes for those meeting strict criteria. Efforts have been made to expand these criteria, whereas others have attempted downstaging approaches. Although locoregional approaches to downstaging are appealing and have demonstrated efficacy, limitations and challenges exists including poor imaging modality to assess response and appropriate endpoints along the process. Recent advances in systemic treatments including immune checkpoint inhibitors alone or in combination with tyrosine kinase inhibitors have prompted the discussion regarding their role for downstaging disease prior to transplantation. Here, we provide a review of prior locoregional approaches for downstaging, new systemic agents and their role for downstaging, and finally, key and critical considerations of the assessment, endpoints, and optimal designs in clinical trials to address this key question.

Downstaging Outcomes for Hepatocellular Carcinoma: Results From the Multicenter Evaluation of Reduction in Tumor Size before Liver Transplantation (MERITS-LT) Consortium

BACKGROUND & AIMS

United Network of Organ Sharing (UNOS) has adopted uniform criteria for downstaging (UNOS-DS) of hepatocellular carcinoma (HCC) before liver transplantation (LT), but the downstaging success rate and intention-to-treat outcomes across broad geographic regions are unknown.

METHODS

In this first multiregional study (7 centers, 4 UNOS regions), 209 consecutive patients with HCC undergoing downstaging based on UNOS-DS criteria were prospectively evaluated from 2016 to 2019.

RESULTS

Probability of successful downstaging to Milan criteria and dropout at 2 years from the initial downstaging procedure was 87.7% and 37.3%, respectively. Pretreatment with lectin-reactive α-fetoprotein ≥10% (hazard ratio, 3.7; P = .02) was associated with increased dropout risk. When chemoembolization (n = 132) and yttrium-90 radioembolization (n = 62) were compared as the initial downstaging treatment, there were no differences in Modified Response Evaluation Criteria In Solid Tumors response, probability of or time to successful downstaging, waiting list dropout, or LT. Probability of LT at 3 years was 46.6% after a median of 17.2 months. In the explant, 17.5% had vascular invasion, and 42.8% exceeded Milan criteria (understaging). The only factor associated with understaging was the sum of the number of lesions plus largest tumor diameter on the last pre-LT imaging, and the odds of understaging increased by 35% per 1-unit increase in this sum. Post-LT survival at 2 years was 95%, and HCC recurrence occurred in 7.9%.

CONCLUSION

In this first prospective multiregional study based on UNOS-DS criteria, we observed a successful downstaging rate of >80% and similar efficacy of chemoembolization and yttrium-90 radioembolization as the initial downstaging treatment. A high rate of tumor understaging was observed despite excellent 2-year post-LT survival of 95%. Additional LRT to reduce viable tumor burden may reduce tumor understaging.