Hepatic artery infusion chemotherapy (HAIC) is a well-established and common treatment for advanced hepatocellular carcinoma (HCC), particularly in East Asia. However, HAIC is not recognized internationally. Although several trials have demonstrated the safety and efficacy of HAIC, evidence corroborating its overall survival (OS) benefits compared with standard treatments is insufficient. Nevertheless, HAIC may provide prominent benefits in selected patients such as patients with portal vein thrombosis or high intrahepatic tumor burden. Moreover, HAIC has been combined with several therapeutic agents and modalities, including interferon-alpha, multikinase inhibitors, radiation therapy, and immunotherapy, to augment its treatment efficacy. Most of these combinations appeared to increase overall response rates compared with HAIC alone, but results regarding OS are inconclusive. Two prospective randomized controlled trials comparing HAIC plus sorafenib with sorafenib alone have reported conflicting results, necessitating further research. As immunotherapy-based combinations became the mainstream treatments for advanced HCC, HAIC plus immunotherapy-based treatments also showed encouraging preliminary results. The trials of HAIC were heterogeneous in terms of patient selection, chemotherapy regimens and doses, HAIC combination agent selections, and HAIC technical protocols. These heterogeneities may contribute to differences in treatment efficacy, thus increasing the difficulty of interpreting trial results. We propose that future trials of HAIC standardize these key factors to reveal the clinical value of HAIC-based treatments for HCC.

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Immunotherapy-related adverse events (irAEs) such as hepatitis or cholestasis have been well recognized. In contrast, acholia was not previously reported as an irAE with a lack of standard treatment. We presented a case of a 68-year-old man with metastatic colon cancer that progressed after several chemotherapy sessions with targeted agents. He received nivolumab plus regorafenib (REGONIVO) as salvage treatment. However, he reported clay-colored stools and jaundice after 3 months of REGONIVO treatment. Computed tomography (CT) revealed no significant biliary tract dilation. Laboratory tests ruled out viral hepatitis or autoimmune hepatitis. Endoscopic retrograde cholangiopancreatography showed multiple filling defects of blood clot formation, and endoscopic retrograde biliary drainage was ineffective. An irAE presenting as acholia and hyperbilirubinemia was diagnosed. Subsequently, the patient was initially administered a corticosteroid only, with an equivalent dose of prednisone (1 mg/kg/day); however, this treatment had only limited effect. After the addition of multiple immunosuppressants, including mycophenolate mofetil and tacrolimus, the severity of hyperbilirubinemia declined and acholia was resolved. This case demonstrated that irAEs can present as acholia and hyperbilirubinemia without significant biliary obstruction. Although the mechanism of such an unusual irAE remains unclear, it seems to be refractory to corticosteroid treatment alone. A more aggressive strategy, such as multiple immunosuppressants, may be advisable.

Background: PD-1 blockade has been approved as treatment for advanced HCC. We previously demonstrated the efficacy of CDK9 inhibition in reducing the expression of inducible proteins and as a treatment for HCC (Shao et al. Oncology 2022). We thus examined the influence of CDK9 inhibition on the expression of PD-L1 in HCC and the potential of improving the efficacy of PD-1 blockade with the combination of CDK9 inhibitors. Methods: We first examined the influence of specific CDK9 inhibitors, AZD4573 and atuveciclib, on interferon-γ (IFN-γ) induced PD-L1 expression of human HCC cell lines HuH7 and Hep3B. Overexpression of CDK9 and siRNA to CDK9 were used to confirm the findings. Similar experiments were repeated in the mouse HCC cell line BNL. To test the in vivo efficacy, we orthotopically implanted BNL cells in the subcapsular area of BALB/c mice, which were then treated with vehicle, CDK9 inhibitors, anti-PD-L1 antibodies, or their combination. To compare with tumor sizes, all mice were sacrificed after 14 days of treatment. To compare survival, the mice were only sacrificed if they met the criteria of animal euthanasia. Results: Both HuH7 and Hep3B cells had minimal PD-L1 expression, which however could be induced using IFN-γ. AZD4573 and atuveciclib decreased the IFN-γ induced PD-L1 expression of HuH7 and Hep3B cells in a dose dependent manner. The flow cytometry results confirmed that membrane PD-L1 expression was also decreased by CDK9 inhibition. Overexpression of CDK9 decreased the influence of these CDK9 inhibitors on PD-L1 expression. CDK9 knockdown using siRNA reduced the IFN-γ induced PD-L1 expression. AZD4573 and atuveciclib also reduce the PD-L1 expression in BNL cell lines. In the orthotopic animal model, the tumors of the sacrificed mice were significantly smaller in mice treated with atuveciclib and an anti-PD-L1 antibody than mice treatment with either alone. The survival of mice treated with the combination was also longer than mice treated with each therapy alone. Conclusion: We demonstrated that CDK9 inhibition could reduce the IFN-γ induced PD-L1 expression of HCC cells. Combination of CDK9 inhibitors and anti-PD-L1 antibodies was more effective than either therapy alone. Citation Format: Ching-Tso Chen, Yu-Yun Shao, Hung-Wei Hsu, Rita R. Wo, Han-Yu Wang, Ann-Lii Cheng, Chih-Hung Hsu. Cyclin dependent kinase 9 (CDK9) inhibition increased efficacy of programmed cell death protein 1 (PD-1) blockade for hepatocellular carcinoma (HCC) through decreasing programmed death-ligand 1 (PD-L1) expression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5985.