Multifunctional Dendronized Polypeptides for Controlled Adjuvanticity

Effects of Secondary Structures and pH on the Self-Assembly of Poly(ethylene glycol)-b-polytyrosine

Different from conventional synthetic polymers, polypeptides exhibit a distinguishing characteristic of adopting specific secondary structures, including random coils, α-helixes, and β-sheets. The conformation determines the rigidity and solubility of polypeptide chains, which further direct the self-assembly and morphology of the nanostructures. We studied the effect of distinct secondary structures on the self-assembly behavior of polytyrosine (PTyr)-derived amphiphilic copolymers. Two block copolymers of enantiopure poly(ethylene glycol)-b-poly(l-tyrosine) (PEG-b-P(l-Tyr)) and racemic poly(ethylene glycol)-b-poly(dl-tyrosine) (PEG-b-P(dl-Tyr)) were synthesized through the ring-opening polymerization of l-tyrosine N-thiocarboxyanhydride (l-Tyr-NTA) and dl-tyrosine N-thiocarboxyanhydride (dl-Tyr-NTA), respectively, by using poly(ethylene glycol) amine as the initiator. PEG44-b-P(l-Tyr)10 adopts a β-sheet conformation and self-assembles into rectangular nanosheets in aqueous solutions, while PEG44-b-P(dl-Tyr)9 is primarily in a random coil conformation with a tiny content of β-sheet structures, which self-assembles into sheaf-like nanofibrils. A pH increase results in the ionization of phenolic hydroxyl groups, which decreases the β-sheet content and increases the random coil content of the PTyr segments. Accordingly, PEG44-b-P(l-Tyr)10 and PEG44-b-P(dl-Tyr)9 self-assemble to form slender nanobelts and twisted nanoribbons, respectively, in alkaline aqueous solutions. The secondary structure-driven self-assembly of PTyr-derived copolymers is promising to construct filamentous nanostructures, which have potential for applications in controlled drug release.

Polymeric nanoparticle-based nanovaccines for cancer immunotherapy

Therapeutic cancer vaccines, which are designed to amplify tumor-specific T cell responses, have been envisioned as one of the most powerful tools for effective cancer immunotherapy. However, increasing the potency, quality and durability of the vaccine response remains a big challenge. In recent years, materials-based delivery systems focusing on the co-delivery of antigens and adjuvants to enhance cancer vaccination therapy have attracted increasing interest. Among various materials, polymeric nanoparticles (NPs) with different physicochemical properties which can incorporate multiple immunological cues are of great interest. In this review, the recent progress in the design and construction of both ex vivo subunit and in situ cancer vaccines using polymeric NPs is summarized. Especially, we will focus on how these NPs improve the adjuvanticity of vaccines. The design principles of polymeric NPs for ex vivo subunit cancer vaccines and in situ cancer vaccination are also discussed. Finally, we want to briefly discuss molecular chaperones in cancer immunity and the applications of our unique self-assembly mixed shell polymeric micelle-based nanochaperones for cancer vaccines.

Self-adjuvanting cancer nanovaccines

Nanovaccines, a new generation of vaccines that use nanoparticles as carriers and/or adjuvants, have been widely used in the prevention and treatment of various diseases, including cancer. Nanovaccines have sparked considerable interest in cancer therapy due to a variety of advantages, including improved access to lymph nodes (LN), optimal packing and presentation of antigens, and induction of a persistent anti-tumor immune response. As a delivery system for cancer vaccines, various types of nanoparticles have been designed to facilitate the delivery of antigens and adjuvants to lymphoid organs and antigen-presenting cells (APCs). Particularly, some types of nanoparticles are able to confer an immune-enhancing capability and can themselves be utilized for adjuvant-like effect for vaccines, suggesting a direction for a better use of nanomaterials and the optimization of cancer vaccines. However, this role of nanoparticles in vaccines has not been well studied. To further elucidate the role of self-adjuvanting nanovaccines in cancer therapy, we review the mechanisms of antitumor vaccine adjuvants with respect to nanovaccines with self-adjuvanting properties, including enhancing cross-presentation, targeting signaling pathways, biomimicking of the natural invasion process of pathogens, and further unknown mechanisms. We surveyed self-adjuvanting cancer nanovaccines in clinical research and discussed their advantages and challenges. In this review, we classified self-adjuvanting cancer nanovaccines according to the underlying immunomodulatory mechanism, which may provide mechanistic insights into the design of nanovaccines in the future.

A Minimalist Binary Vaccine Carrier for Personalized Postoperative Cancer Vaccine Therapy

In recent years, significant evolutions have been made in applying nanotechnologies for prophylactic and therapeutic cancer vaccine design. However, the clinical translation of nanovaccines is still limited owing to their complicated compositions and difficulties in the spatiotemporal coordination of antigen-presenting cell activation and antigen cross-presentation. Herein, a minimalist binary nanovaccine (BiVax) is designed that integrates innate stimulating activity into the carrier to elicit robust antitumor immunity. The authors started by making a series of azole molecules end-capped polyethylenimine (PEI-M), and were surprised to find that over 60% of the PEI-M polymers have innate stimulating activity via activation of the stimulator of interferon genes pathway. PEI-4BImi, a PEI-M obtained from a series of polymers, elicits robust antitumor immune responses when used as a subcutaneously injected nanovaccine by simply mixing with ovalbumin antigens, and this BiVax system performs much better than the traditional ternary vaccine system, as well as, commercialized aluminum-containing adjuvants. This system also enables the fast preparation of personalized BiVax by compositing PEI-4BImi with autologous tumor cell membrane protein antigens, and a 60% postoperative cure rate is observed when combined with immune checkpoint inhibitors.