Autophagy inhibition recovers deficient ICD-based cancer immunotherapy.

ICD effect is usually accompanied with robust autophagy that can depredate immune-associated antigens in tumors, thereby weakening the immune response against tumor growth. To circumvent this dilemma, we combined an ICD inducer (Shikonin, SHK) with an autophagy inhibitor (hydroxychloroquine, HCQ) for colon cancer immunotherapy. Notably, HCQ boosted SHK-induced antigen exposure in colon cancer in vitro and in vivo. However, autophagy inhibition caused loss of ATP, which compromised antitumor immune response. Therefore, a compensatory strategy was employed by introducing ATP as a remote loading gradient of the liposome to encapsulate HCQ (LipHCQa). LipHCQa achieved an excellent antitumor efficiency without dampening the immune response. Furthermore, a systematic determination of the optimal dosage of combined LipSHK and LipHCQa suggested that autophagy inhibiting at an appropriate dosage level was beneficial for maximizing ICD-based antitumor immunity. This study proved that autophagy inhibitors can recover the deficient ICD-based antitumor immune response and present potential clinical applications for cancer immunotherapy.

Low dose shikonin and anthracyclines coloaded liposomes induce robust immunogenetic cell death for synergistic chemo-immunotherapy.

Chemo-immunotherapy based on immunogenic cell death (ICD) is a promising strategy for cancer therapy. However, the effective ICD requires a high dosage of ICD stimulus, which could be associated to a dose-dependent toxicity. Therefore, in this study, a liposome remote-loaded with shikonin (a potent ICD stimulus) was developed, with the ability to effectively induce ICD at high dosage in vivo. However, a hepatotoxic effect was observed. To circumvent this problem, shikonin was combined with the anthracycline mitoxantrone or doxorubicin to develop co-loaded liposomes inducing a synergistic ICD effect and cytotoxicity to tumor cells. Cytotoxicity and uptake experiment in vitro were performed to analyze the optimal synergistic ratio of shikonin and anthracyclines based on a "formulated strategy". Interestingly, copper mediated co-loaded liposomes resulted in a pH and GSH dual-responsive release property. More importantly, pharmacokinetics and tumor biodistribution studies revealed an outstanding capacity of ratiometric delivery of dual drugs. Thus, the dual-loaded liposome enhanced the antitumor effect by the stimulation of a robust immune response at lower doses of the drugs with a higher safety compared to single-loaded liposomes. Summarized, the current work provided a reference for a rational design and development of liposomal co-delivery system of drugs and ICD-induced chemo-immunotherapy, and established a potential clinical application of shikonin-based drug combinations as a new chemo-immunotherapeutic strategy for cancer treatment.