Targeting the hepatic circadian clock concomitant with tyrosine kinase inhibition reverses late-stage hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths. Most patients present at advanced stages, and the effectiveness of tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors is constrained by limited patient response. A subset of HCC shows elevated expression of the promoter 2 ("P2")-driven hepatocyte nuclear factor 4 alpha (HNF4α) isoform, which directly transcriptionally represses the circadian brain and muscle ARNT-like protein 1 (BMAL1) transcription factor. This subtype of HCC is robustly inhibited by the plant-based flavonoid nobiletin (NOB), a circadian-fortifying compound. Using patient-matched human HCC and serum, we show that BMAL1-deficient HCC shows exaggerated carnitine palmitoyl transferase expression and related metabolite abundance and that P2-HNF4α regulates the carnitine palmitoyl transferase I gene. Finally, using different preclinical models, we show that the anti-tumor activity of TKIs, when they are co-administered with NOB, is maximal. Our results suggest that chronotherapy and combination therapy might provide improved clinical outcomes for individuals with BMAL1-deficient HCC.