Molecular markers of response to anti-PD1 therapy in advanced hepatocellular carcinoma.

BACKGROUND AND AIMS

Single agent anti-PD1 checkpoint inhibitors convey outstanding clinical benefits in a small fraction (∼20%) of patients with advanced hepatocellular carcinoma (aHCC) but the molecular mechanisms determining response are unknown. To fill this gap, we herein analyze the molecular and immune traits of aHCC in patients treated with anti-PD1.

METHODS

Overall, 111 tumor samples from patients with aHCC were obtained from 13 centers prior to systemic therapies. We performed molecular analysis and immune deconvolution using whole genome expression data (n=83), mutational analysis (n=72) and histological evaluation with an endpoint of objective response.

RESULTS

Among 83 patients with transcriptomic data, 28 were treated in frontline whereas 55 patients were treated after tyrosine-kinase inhibitors (TKI) either in 2nd or 3rd line. Responders treated in frontline showed upregulated Interferon-γ-signaling and MHCII-related antigen presentation. We generated an 11-gene signature (IFNAP), capturing these molecular features, which predicts response and survival in patients treated with anti-PD1 in frontline. The signature was validated in a separate cohort of aHCC and >240 patients with other solid cancer types where it also predicted response and survival. Of note, the same signature was unable to predict response in archival tissue of patients treated with frontline TKIs, highlighting the need for fresh biopsies prior to immunotherapy.

CONCLUSION

IFN-signaling and MHCII-related genes are key molecular features of HCCs responding to anti-PD1. A novel 11-gene signature predicts response in frontline aHCC - but not in patients pre-treated with TKIs. These results have to be confirmed in prospective studies and highlight the need for biopsies prior immunotherapy to identify biomarkers of response.