Modification‐Driven Nanocarriers: Ovarian Cancer Cell Membrane– Camouflaged Indoximod/Doxorubicin Co‐Delivery Systems for Synergistic Immunochemotherapy

ABSTRACT Among the three primary gynecological malignancies, ovarian cancer has the highest mortality rate, and its onset is often insidious. Despite standard treatments, relapse and drug resistance remain major challenges. Doxorubicin (DOX) is known to induce immunogenic cell death (ICD); however, some patients still experience tumor resistance and recurrence owing to tumor‐driven immunosuppression. Indoleamine 2,3‐dioxygenase (IDO), which is highly expressed in tumor tissues, impairs T‐cell function and differentiation, thereby promoting immunosuppression. Consequently, combining the IDO inhibitor indoximod (IND) with DOX may reverse immunosuppression and enhance both T‐cell–mediated and ICD‐driven anticancer effects. However, both drugs are limited by high systemic toxicity and poor tumor targeting, necessitating the use of nanocarriers to improve delivery efficiency and minimize toxicity. This study aims to develop novel cell membrane–camouflaged liposomes capable of co‐delivering IND and DOX (DOX/IND@cmLPs) for ovarian cancer therapy and to evaluate its anticancer effects in vitro and in vivo. The particle size of DOX/IND@cmLPs is measured as 111.7 ± 2.7 nm using a Malvern Zetasizer Pro, with a zeta potential of −22.4 ± 4.00 mV. Entrapment efficiency (EE) is assessed using ultra‐high performance liquid chromatography and ultraviolet spectrophotometry, yielding EE values of 85.1% ± 3.4% for DOX and 23.9% ± 1.3% for IND. At both pH 7.4 and pH 5.5, DOX release from DOX/IND@cmLPs is rapid during the first 24 hours, followed by a slower, more sustained release. Coomassie Brilliant Blue staining and Western Blot analysis confirmed successful encapsulation of the cell membrane in the liposomes. The potent antitumor effect of DOX/IND@cmLPs is demonstrated via CellTiter‐Glo assays in vitro. Flow cytometry and immunofluorescence staining revealed an increased ratio of CD8 + T cells to Treg cells in tumor tissues, suggesting that DOX/IND@cmLPs may partially reverse local tumor‐induced immunosuppression. Reduced Ki‐67 expression and increased TdT‐mediated dUTP nick‐end labeling positive cell ratios in tumor sections indicated that DOX/IND@cmLPs treatment suppressed tumor proliferation and promoted apoptosis. Immunohistochemistry showed alterations in mammalian target of rapamycin (mTOR)‐related pathway proteins in tumors. Furthermore, DOX/IND@cmLPs could induce an abscopal effect and provide long‐lasting tumor suppression in a subcutaneous mouse model. In this study, a formulation of DOX/IND‐loaded liposomes camouflaged with ovarian cancer cell membranes is successfully developed, and their stable physicochemical properties are confirmed. As an effective nanodrug delivery system, DOX/IND@cmLPs exhibited enhanced tumor‐targeting and immune‐mediated anticancer activity both in vitro and in vivo, indicating their potential as a platform for future combined chemotherapy and immunotherapy.