Mannose Modified Co-Loaded Zoledronic Liposomes Deplete M2-tumor-associated Macrophages to Enhance Anti-Tumor Effect of Doxorubicin on TNBC

As the most numerous inflammatory cell group in tumor microenvironment, tumor-associated macrophages (TAMs) have an essential effect in tumor therapy and are potential therapeutic targets. M2 type tumor-associated macrophages (M2-TAMs) were involved in the entire process of tumor development, invasion, and metastasis, obstructing the anti-tumor effect of chemotherapy drugs and nano-medicine. This study aimed to construct a mannose modified co-loaded zoledronic acid and doxorubicin liposomes (Man-LP@ZOL/DOX) for improving the anti-tumor effect by suppressing M2-TAMs on triple-negative breast cancer (TNBC). The size, PDI, and Zeta-potential of Man-LP@ZOL/DOX liposomes were determined to be 212.80±7.74 nm, 0.1413±0.0232, -33.63±0.49 mV, respectively. The Man-LP@ZOL/DOX's EE% and DL% of ZOL as measured were 17.21±2.26% and 1.56±0.21%, while for DOX, they were 84.42±2.05% and 5.12±0.14%. The uptake of Man-LP into cells was increased when it was modified with a TAMs target ligand. The liposomes inhibited the invasion of MDA-MB-231 cells induced by M2-TAMs, and expression of biomarkers on M2-TAMs (Arg1 and CD206 in vitro, CD68, and CD206 in vivo) was apparent. Moreover, co-loaded drugs liposome system remarkably enhanced anticancer effects both in vitro and vivo combined with ZOL. In conclusion, all these results established that Man-LP@ZOL/DOX could enhance anti-tumor effect of DOX via depleting M2-TAMs on TNBC.

Optimized 5-Fluorouridine Prodrug for Co-Loading with Doxorubicin in Clinically Relevant Liposomes

Liposome-based drug delivery systems have allowed for better drug tolerability and longer circulation times but are often optimized for a single agent due to the inherent difficulty of co-encapsulating two drugs with differing chemical profiles. Here, we design and test a prodrug based on a ribosylated nucleoside form of 5-fluorouracil, 5-fluorouridine (5FUR), with the final purpose of co-encapsulation with doxorubicin (DOX) in liposomes. To improve the loading of 5FUR, we developed two 5FUR prodrugs that involved the conjugation of either one or three moieties of tryptophan (W) known respectively as, 5FUR−W and 5FUR−W3. 5FUR−W demonstrated greater chemical stability than 5FUR−W3 and allowed for improved loading with fewer possible byproducts from tryptophan hydrolysis. Varied drug ratios of 5FUR−W: DOX were encapsulated for in vivo testing in the highly aggressive 4T1 murine breast cancer model. A liposomal molar ratio of 2.5 5FUR−W: DOX achieved a 62.6% reduction in tumor size compared to the untreated control group and a 33% reduction compared to clinical doxorubicin liposomes in a proof-of-concept study to demonstrate the viability of the co-encapsulated liposomes. We believe that the new prodrug 5FUR−W demonstrates a prodrug design with clinical translatability by reducing the number of byproducts produced by the hydrolysis of tryptophan, while also allowing for loading flexibility.