Cancer Immunotherapy via Targeting Cancer Stem Cells Using Vaccine Nanodiscs

Cancer stem cells (CSCs) proliferate extensively and drive tumor metastasis and recurrence. CSCs have been identified in over 20 cancer types to date, but it remains unknown how to target and eliminate CSCs in vivo. Aldehyde dehydrogenase (ALDH) is a marker that has been used extensively for isolating CSCs. Here we present a novel approach to target and reduce the frequency of ALDH^high CSCs by vaccination against ALDH. We have identified ALDH1-A1 and ALDH1-A3 epitopes from CSCs and developed synthetic high-density lipoprotein nanodiscs for vaccination against ALDH^high CSCs. Nanodiscs increased antigen trafficking to lymph nodes and generated robust ALDH-specific T cell responses. Nanodisc vaccination against ALDH^high CSCs combined with anti-PD-L1 therapy exerted potent antitumor efficacy and prolonged animal survival in multiple murine models. Overall, this is the first demonstration of a simple nanovaccine strategy against CSCs and may lead to new avenues for cancer immunotherapy against CSCs.

Synthetic HDL Nanoparticles Delivering Docetaxel and CpG for Chemoimmunotherapy of Colon Adenocarcinoma

Colon carcinomas comprise over two-thirds of all colorectal cancers with an overall 5-year survival rate of 64%, which rapidly decreases to 14% when the cancer becomes metastatic. Depending on the stage of colon carcinoma at diagnosis, patients can undergo surgery to attempt complete tumor resection or move directly to chemotherapy with one or a combination of drugs. As with most cancers, colon carcinomas do not always respond to chemotherapies, so targeted therapies and immunotherapies have been developed to aid chemotherapy. We report the development of a local combination therapy for colon carcinoma whereby chemo- and immunotherapeutic entities are delivered intratumorally to maximize efficacy and minimize off-target side effects. A hydrophobic chemotherapeutic agent, docetaxel (DTX), and cholesterol-modified Toll-like receptor 9 (TLR9) agonist CpG (cho-CpG) oligonucleotide are co-loaded in synthetic HDL (sHDL) nanodiscs. In vivo survival analysis of MC-38 tumor-bearing mice treated intratumorally with DTX-sHDL/CpG (median survival; MS = 43 days) showed significant improvement in overall survival compared to mice treated with single agents, free DTX (MS = 23 days, p < 0.0001) or DTX-sHDL (MS = 28 days, p < 0.0001). Two of seven mice treated with DTX-sHDL/CpG experienced complete tumor regression. None of the mice experienced any systemic toxicity as indicated by body weight maintenance and normal serum enzyme and protein levels. In summary, we have demonstrated that chemo- and immunotherapies can be co-loaded into sHDLs, delivered locally to the tumor, and can be used to improve survival outcomes significantly compared to chemotherapy alone.

Size-Controlled Iron Oxide Nanoplatforms with Lipidoid-Stabilized Shells for Efficient Magnetic Resonance Imaging-Trackable Lymph Node Targeting and High-Capacity Biomolecule Display

Nanoplatforms for biomolecule delivery to the lymph nodes have attracted considerable interest as vectors for immunotherapy. Core-shell iron oxide nanoparticles are particularly appealing because of their potential as theranostic magnetic resonance imaging (MRI)-trackable vehicles for biomolecule delivery. The key challenge for utilizing iron oxide nanoparticles in this capacity is control of their coating shells to produce particles with predictable size. Size determines both the carrier capacity for biomolecule display and the carrier ability to target the lymph nodes. In this study, we develop a novel coating method to produce core-shell iron oxide nanoparticles with controlled size. We utilize lipidlike molecules to stabilize self-assembled lipid shells on the surface of iron oxide nanocrystals, allowing the formation of consistent coatings on nanocrystals of varying size (10-40 nm). We further demonstrate the feasibility of leveraging the ensuing control of nanocarrier size for optimizing the carrier functionalities. Coated nanoparticles with 10 and 30 nm cores supported biomolecule display at 10-fold and 200-fold higher capacities than previously reported iron oxide nanoparticles, while preserving monodisperse sub-100 nm size populations. In addition, accumulation of the coated nanoparticles in the lymph nodes could be tracked by MRI and at 1 h post injection demonstrated significantly enhanced lymph node targeting. Notably, lymph node targeting was 9-40 folds higher than that for previously reported nanocarriers, likely due to the ability of these nanoparticles to robustly maintain their sub-100 nm size in vivo. This approach can be broadly applicable for rational design of theranostic nanoplatforms for image-monitored immunotherapy.