Modeling sequential systemic therapy for unresectable hepatocellular carcinoma in the era of immunotherapy: What comes next?

324 Background: Atezolizumab plus Bevacizumab represents the new best performing first-line approach for unresectable hepatocellular carcinoma (u-HCC). However, the best sequential strategy after every first-line failure (for progression or intolerance) remains elusive, and options for retreating patients failing Atezolizumab plus Bevacizumab with multi-kinase inhibitors (MKI) or immune checkpoint inhibitor (ICI) are yet undefined. Methods: We developed a Markov model to analyze simulated-Overall Survival (s-OS) of second-line ICIs or MKIs after first-line Atezolizumab plus Bevacizumab over a lifetime horizon. For first-line therapy, PFS of Atezolizumab plus Bevacizumab was extracted from Imbrave 150 trial and it was used as endpoint since it is not influenced by post-progression survival. For second-line retreatment, pooled OS of MKIs (Regorafenib and Cabozantinib), or ICIs (Nivolumab and Pembrolizumab) were adopted. Survival estimates for sequential settings considered the proportion of patients who did not receive second-line therapy due to death during first-line therapy. Individual patient survival data were extracted from PFS and OS Kaplan-Meier curves of RESORCE trial for Regorafenib, CELESTIAL trial for Cabozantinib, CheckMate-040 for Nivolumab and Keynote-240 for Pembrolizumab. Each reconstructed survival curve was inspected for accuracy and was compared with originally published curves. Results: First-line Atezolizumab plus Bevacizumab followed by second-line ICIs turned on from the model as the best sequential strategy (median s-OS 24 months; 95% Confidence Interval (CI) 23-26 months) and extends survival when compared Atezolizumab plus Bevacizumab followed by MKIs (median s-OS 20 months; 95% CI 19-21 months). Conclusions: To our knowledge and given the absence of adequately designed sequential RCTs, this is the first model to date which suggests, with a proper methodological approach, an accurate estimate of outcome of patients with u-HCC treated by sequential systemic therapies. In patients with u-HCC failing first-line treatment, modelling estimates of s-OS for each retreatment strategies may assist in choosing the most promising sequences in order to plan appropriate RCTs.