Chemotherapy-induced recruitment of myeloid-derived suppressor cells abrogates efficacy of immune checkpoint blockade

• Published in: JHEP reports 2021-04, Vol.3 (2), p.100224, Article 100224
• Main Authors: Kwong, Tsz Tung, Wong, Chi Hang, Zhou, Jing Ying, Cheng, Alfred Sze Lok, Sung, Joseph Jao Yiu, Chan, Anthony Wing Hung, Chan, Stephen Lam
• Format: Article
• Language: English
• Subjects: Chemotherapy; Hepatocellular carcinoma; Immune checkpoint blockade; Immunotherapy; Myeloid-derived suppressor cell; Short Communication; TACE; Tumor microenvironment
• ISSN: 2589-5559; 2589-5559
• DOI: 10.1016/j.jhepr.2020.100224

Immune checkpoint blockade (ICB) has been approved for treatment of hepatocellular carcinoma (HCC). However, many patients with advanced HCC are non-responders to ICB monotherapy. Cytotoxic chemotherapy has been proposed to modulate the tumor microenvironment (TME) and sensitize tumors to ICB. Thus, we aimed to study the combination of cytotoxic chemotherapy and ICB in an orthotopic HCC model. Preclinical orthotopic HCC mouse models were used to elucidate the efficacy of 5-fluorouracil (5-FU) and ICB. The mice were intrahepatically injected with RIL-175 or Hepa1-6 cells, followed by treatment with 5-FU and anti-programmed cell death ligand 1 (PD-L1) antibody. Myeloid-derived suppressor cells (MDSCs) were depleted to validate their role in attenuating sensitivity to immunotherapy. Flow cytometry-based immune profiling and immunofluorescence staining were performed in mice and patient samples, respectively. 5-FU could induce intratumoral MDSC accumulation to counteract the infiltration of T lymphocytes and natural killer cells, thus abrogating the anti-tumor efficacy of PD-L1 blockade. In clinical samples, MDSCs accumulated and CD8+ T cell numbers decreased following transarterial chemoembolization. 5-FU can trigger the accumulation of immunosuppressive MDSCs, impairing the response to PD-L1 blockade in HCC. Our data suggest that the combination of specific chemotherapy and ICB may impair anti-tumor immune responses, warranting further study in preclinical models and consideration in clinical settings. Our findings suggest that some chemotherapies may impair the anti-tumor efficacy of immunotherapy. Further studies are required to uncover the specific effects of different chemotherapies on the immunological profile of tumors. This data will be critical for the rational design of combination immunotherapy strategies for patients with hepatocellular carcinoma. [Display omitted] •Some chemotherapeutic agents could counteract the efficacy of PD-L1 blockade in HCC.•5-FU mediates MDSC accumulation in tumors which blunts the response to immunotherapy.•MDSCs are enriched in HCC patients treated with transarterial chemoembolization.