Profound tumor response to combined CTLA-4 and PD-1 inhibition in systemic fourth line therapy observed in a patient with hepatocellular carcinoma harboring SETD2 and LRP1B mutations.

Immunotherapy has become the standard of care in advanced HCC but is only approved in first- or second-line treatment. We report a patient with HCC refractory to several lines of tyrosine kinase inhibitors, who was treated with Ipilimumab and Nivolumab (Ipi/Nivo) as the fourth line. The tumor responded profoundly to Ipi/Nivo. Established biomarker-predicting responses to immunotherapy, such as a high PD-L1 staining, a high combined-positive score, microsatellite instability or a high tumor mutational burden, were not detected. Potential negative predictive markers for response to immunotherapy such as CTNNB1 and TERT were present. This constellation puts the spotlight on two mutations observed here in the SET domain-containing 2 (SETD2) and low-density lipoprotein receptor-related protein 1b (LRP1B) genes, which may explain the outstanding response. Our case demonstrates that immunotherapy can be efficient in a late-line scenario, resulting in long-term survival. Further studies should prospectively evaluate the value of SETD2 and LRP1B alterations as predictors for the success of immunotherapy in HCC.