Pharmaceutical nanocarriers can be prepared from lipids, polymers, metals, inorganics, and other materials. Nano-medicines target tumors via either passive (also known as the Enhanced Permeation and Retention effect) and/or active mechanisms. Research and development in the field of cancer nanotherapeutics have experienced an exponential growth since early 2000's since the commercialization of the first-generation anti-tumor nanomedicines including DOXIL (doxorubicin hydrochloride, Baxter) and Abraxane (paclitaxel, Bristol Myers Squibb). i. Lipid NPs 169 are currently most widely used NPs and exhibit high growth rate as compared to other NPs in the field of cancer immunotherapy (Fig. ). Lipid-based NPs are superior to other nanosized drug delivery systems in minimizing systemic toxicity while maintaining adequate solubility 170 and are thus the most common type of regulatory approved nanomedicines. They have been applied in drug delivery since the discovery of liposomes in the 1960s, but marked several serious advancements: (i) with the introduction of PEGylation, 172 which increased their circulation half-lives further improving their effectiveness, 173 (ii) with the discovery of the cationic/ionizable liposomes able to deliver anionic nucleic acids, 174 as well as (iii) with the development of the solid lipid nanoparticles and the nanostructured lipid carriers offering higher payload and stability, and largely improved scalability. Thus, in cancer immunotherapy, lipid-based NPs could successfully deliver small molecules and mRNA therapies in vivo to achieve remarkable antitumor activity. ii. Metal NPs. Inorganic NPs provide an appropriate framework in which multiple modules can be combined to give multifunctional capabilities. Metallic NP formulations are particularly advantageous because of their potential for dense surface functionalization and capability for optical or thermal based therapeutic and diagnostic methods. 177 iii. Magnetic iron oxide NPs. Iron oxide NPs can generate heat when exposed to an alternating magnetic field, a property that has been utilized to induce cell death and stimulate an immune response in hyperthermia-based cancer treatment. Iron oxide NPs can also be used as contrast agents for magnetic resonance imaging, allowing for noninvasive tracking of immune cell migration and infiltration into tumor sites. In order to enhance their cellular uptake and effectiveness, these NPs can be modified with a specific coating, conjugated to drugs, proteins, enzymes, antibodies, or nucleotides, and can be directed to an organ, tissue, or tumor sites using external magnetic field; they can be used in the development of dual-purpose probes for the in vivo transfection of siRNA. 178 iv. Silver NPs. Silver NPs known for their antibacterial activity, are also known to enhance the anti-tumor effects of anticancer drugs in combination therapies, allowing use of lower doses to reduce cytotoxic effects and increase efficacy. They can thus operate as direct anti-cancer agents, as well as delivery platforms of various cytotoxic drugs or enhance the anti-cancer performance of combinational partners upon chemo-or radiotherapy. Silver nanoparticles can exhibit a plasmon resonance effect and generate heat when exposed to specific wavelengths. This property can be harnessed for photothermal therapy, where the localized heat generated by the nanoparticles damages cancer cells and stimulates an immune response. v. Gold NPs. Gold NPs are a multifunctional therapeutic modality, performing as targeted delivery systems for vaccines, nucleic acids, and immune antibodies, as theranostic agents, and as tools in photothermal cancer therapy. They have been successfully applied also in medical imaging, such as radiotherapy, magnetic resonance angiography, and photoacoustic imaging. Gold nanostructures including nanoparticles, nanorods, nanocages, etc., are easily synthesizable in diverse shapes and sizes through various chemical, physical, or biological methods, which empowers their manageability, since even minor modifications of their size and shape can produce significant alterations in their functional properties including biodistribution, metabolism, cytotoxicity, and immunogenicity. Similar to silver NPs, gold NPs can be utilized in photothermal therapy via localized plasmon surface resonance. 184 vi. Silica NPs. Mesoporous silica exhibits high porosity, appropriate biocompatibility, and facile surface functionalization. Silica NPs can be engineered to various shapes, sizes, and surface properties, making them versatile tools for targeted drug delivery, imaging, and immunomodulation. After the introduction of sub-micrometer mesoporous silica termed MCM-41 and its successful application as a nanocarrier, 187 it has been regarded as a promising drug delivery system. Moreover, mesoporous silica exhibits self-adjuvant property, significantly enhancing anticancer immunity without additional immunomodulators. Mesoporous silica has emerged as a prospective nanocarrier for cancer vaccines as well, 190 alleviating antitumor immunity through dual loading of antigen and adjuvant on a single platform. 185 vii. Polymeric NPs. Polymeric nanocarriers are beneficial for immunotherapy approaches because they can be modulated with adequate physical properties, encapsulants, and surface ligands; they can be also tailored to co-deliver multiple therapeutic agents to cancer or immune cells. Various stimuli-responsive (e.g., enzyme-, pH-and redoxresponsive) polymers, including natural and synthetic polymers, have been utilized as smart nanocarriers for immunotherapy applications. Redox-responsive polymeric nanohydrogels exhibiting tissue-like mechanical properties and high porosity have been extensively studied and shown to be effective in protecting payloads including protein drugs, gene therapeutics, and small-molecule anticancer drugs in blood circulation, as well as in their targeted release. The most commonly used natural polysaccharides include dextran, polysialic acid, hyaluronic acid, chitosan, and heparin, while polyvinyl pyrrolidone, polyacrylamide, polyvinyl alcohol, polyethylene glycol (PEG), and PEG copolymers such as poloxamines, poloxamers, and polysorbates are preferred synthetic polymers. Smart polymeric nanoparticles have been demonstrated to enhance tumor immunotherapy, to alleviate immunosuppression, and prevent cancer cells from evading the immune system. 2. Exosomes Superior innate stability, low immunogenicity, biocompatibility, and excellent capacity for membrane penetration allow exosomes to be valuable natural nanocarriers for efficient drug delivery. As important mediators of intercellular communications, exosomes are increasingly gaining interest in the context of cancer immunotherapy. Exosomes, either tumor-derived, comprising tumor-associated antigens, or derived from dendritic cells presenting antigens, can trigger immune activation and therefore they can be used in developing anti-cancer vaccines. Moreover, tumor-derived exosomes hold information from primary cells and express complexes of MHC epitopes and co-stimulatory proteins, thus they can activate CD8 T-cells, which offer unique therapeutic approaches for developing cancer vaccines. Exosomes participate in the formation of the cancer immunosuppressive microenvironment, thus tumor exosome production control might be an effective treatment strategy. Exosomes also play a key role in the PD-1/PD-L1 immune checkpoint inhibitor treatment.