Supplementary Material for: Conversion Ability of Immunotherapy in Hepatocellular Carcinoma: Insights from the International Converse Study

Introduction: The potential for curative conversion with immunotherapy-based systemic treatment used with noncurative intent in patients with hepatocellular carcinoma (HCC) remains debated. This study aimed to provide a reliable epidemiological snapshot of response patterns to Atezolizumab plus Bevacizumab (AB) therapy, with a focus on curative conversion rates.
Methods: Patients with HCC undergoing first-line noncurative AB or Lenvatinib (LENV, used as reference) from 2019 to 2023 were included, using centre-level aggregate data from a broad international consortium. The primary endpoint was the curative conversion rate, differentiating potential conversion (PC) - when objective response (OR) resulted in a consistent decrease in tumour burden and alpha-fetoprotein levels - from actual conversion (AC), when OR led to curative treatment. Secondary endpoints included OR, under-conversion (UC; [PC - AC]/OR) rates, and crude survival rates of AC patients. A meta-analytic approach was employed to analyse aggregate data.
Results: Forty-eight international centres treating 2,379 patients with HCC with a noncurative intent (1,401 with AB and 978 with LENV) were included. A significant discrepancy was observed between PC (16% and 13% for AB and LENV, p=0.03) and AC rates (3% for both AB and LENV, p=0.14).
UC rates remained similarly high (40% and 36% for AB and LENV, p=0.93), despite differing OR rates (29% and 24% for AB and LENV, p=0.01). Subgroup and meta-regression analyses did not identify any clear treatment, centre, or patient patterns that explained the high UC rate. The 3-year survival rate for the 72 patients who underwent a curative conversion after AB was 93%.
Conclusions: Although patients treated with AB achieved higher OR and PC rates than those treated with LENV, AC remained similarly low, highlighting a potentially worrisome UC phenomenon in real life, also with novel immunotherapy-based combinations.