Engineering platforms for localized long-acting immune modulation
Authors: Corrine Ying Xuan Chua, Dixita Ishani Viswanath, David P. Huston, Alessandro Grattoni
Journal: Journal of Allergy and Clinical Immunology (2024)

Systemic immunotherapeutics have been a clinical staple in the treatment of cancer, infectious diseases, organ and cell transplantation, autoimmunity, and allergies. Although their utility remains unquestioned, systemic administration of these drugs is associated with limited efficacy, significant adverse off-target effects, transient activity, and the requirement for frequent repeated dosing. To this end, recent technological advancements have provided novel means for sustained drug delivery to specific tissues and targeted localized approaches for immunotherapeutics. In this article, we present various cutting-edge platform technologies, including implants, multireservoir systems, and scaffolds encapsulating immunomodulatory agents for local administration. Examples of their application in cancer, cell transplantation, allergy, and infectious diseases are discussed, highlighting the potential of such systems for innovative immunomodulatory intervention. Systemic immunotherapeutics have been a clinical staple in the treatment of cancer, infectious diseases, organ and cell transplantation, autoimmunity, and allergies. Although their utility remains unquestioned, systemic administration of these drugs is associated with limited efficacy, significant adverse off-target effects, transient activity, and the requirement for frequent repeated dosing. To this end, recent technological advancements have provided novel means for sustained drug delivery to specific tissues and targeted localized approaches for immunotherapeutics. In this article, we present various cutting-edge platform technologies, including implants, multireservoir systems, and scaffolds encapsulating immunomodulatory agents for local administration. Examples of their application in cancer, cell transplantation, allergy, and infectious diseases are discussed, highlighting the potential of such systems for innovative immunomodulatory intervention. Immunomodulatory therapies engage immune-relevant targets to manage or treat a variety of diseases. Depending on the disease, such therapies can be conventional small molecule pharmaceutics or biologic agents, including nucleic acids, proteins, and cells.1Campa-Carranza J.N. Paez-Mayorga J. Chua C.Y.X. Nichols J.E. Grattoni A. Emerging local immunomodulatory strategies to circumvent systemic immunosuppression in cell transplantation.Expert Opin Drug Del. 2022; 19: 595-610Crossref PubMed Scopus (7) Google Scholar Immunomodulatory agents have demonstrated efficacy in clinical applications such as cancer, infectious diseases, transplantation and autoimmunity, and allergic diseases. However, transient efficacy and unfavorable physiologic kinetics subsequent to therapeutic administration pose challenges. Systemic delivery causes treatment dispersion, whereas efficacy hinges on the presence of high therapeutic concentrations and activity within target tissues or at the disease site.2Kichloo A. Albosta M. Dahiya D. Guidi J.C. Aljadah M. Singh J. et al.Systemic adverse effects and toxicities associated with immunotherapy: a review.World J Clin Oncol. 2021; 12: 150-163Crossref PubMed Google Scholar Because of transient activity or low therapeutic levels, repeated administration is typically required but not always feasible. Further, serious adverse reactions such as on-target side effects owing to overactivation or oversuppression of the immune system are impediments to successful disease management. Additionally, off-target toxicities attributable to treatment nonspecificity further exacerbate safety concerns. To this end, technological innovations that provide a targeted approach with a longer duration of disease management are poised to be the new frontier of immunomodulatory therapies. Long-acting approaches could reduce dosage, administration frequency, and toxicities, which in turn improves medication adherence, yielding a long-lasting preventative or curative effect. Of relevance, long-acting disease-targeting agents and platforms are clinically established for chronic conditions such as HIV,3Pons-Faudoa F.P. Di Trani N. Capuani S. Campa-Carranza J.N. Nehete B. Sharma S. et al.Long-acting refillable nanofluidic implant confers protection against SHIV infection in nonhuman primates.Science Translational Medicine. 2023; 15eadg2887Crossref PubMed Scopus (6) Google Scholar diabetes, and psychiatric illnesses.4Baryakova T.H. Pogostin B.H. Langer R. McHugh K.J. Overcoming barriers to patient adherence: the case for developing innovative drug delivery systems.Nature Reviews Drug Discovery. 2023; 22: 387-409Crossref PubMed Scopus (34) Google Scholar Considering the success of these approaches, we highlight a few platform technologies developed for long-acting immunomodulation to achieve immune control of cancer, infectious diseases, cell transplantation, and allergy, with a particular focus on localized approaches (Fig 1). Immunotherapy has transformed cancer treatment in an unprecedented manner. However, inherent or acquired immune heterogeneity leads to variable treatment responses. Immune evasion is a leading contributor to treatment failure. Thus, platforms that can educate the immune system to identify foreign, nonself targets allows for eluding evasion. Pertinent to this, various technologies have been developed in the context of in situ cancer vaccines,5Liu H.-C. Davila Gonzalez D. Viswanath D.I. Vander Pol R.S. Saunders S.Z. Di Trani N. et al.Sustained intratumoral administration of agonist CD40 antibody overcomes immunosuppressive tumor microenvironment in pancreatic cancer.Adv Sci. 2023; 102370054Google Scholar,6Yousefpour P. Ni K. Irvine D.J. Targeted modulation of immune cells and tissues using engineered biomaterials.Nat Rev Bioeng. 2023; 1: 107-124Crossref PubMed Google Scholar and their sphere of applicability is broad and extends to vaccines for infectious diseases. These typically rely on biodegradable in situ–forming hydrogels, polymers, implants, or nanoformulations that are capable of sustained delivery of immunomodulators and antigens. In a preclinical setting, some of these platforms have been highly efficacious in various tumor models and infectious disease settings and hold much promise for clinical translation.7Ou B.S. Saouaf O.M. Baillet J. Appel E.A. Sustained delivery approaches to improving adaptive immune responses.Adv Drug Deliver Rev. 2022; 187114401Crossref PubMed Scopus (30) Google Scholar However, ultimate clinical success hinges on multiple factors, including the practicality of the approach and patient acceptability among others. Of note, some of these systems may require frequent booster administration, which may be unfeasible and limit the clinical relevance of the technology. To this end, various technologies capable of addressing the need for long-term drug8Liu H.-C. Viswanath D.I. Pesaresi F. Xu Y. Zhang L. Di Trani N. et al.Potentiating antitumor efficacy through radiation and sustained intratumoral delivery of anti-CD40 and anti-PDL1.Int J Radiat Oncol Biol Phys. 2021; 110: 492-506Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar and antigen delivery have been developed. Among them, the NanoLymph was designed as a localized immunomodulatory system for immune cell homing and/or reprogramming against specific targets.9Viswanath D.I. Liu H.C. Huston D.P. Chua C.Y.X. Grattoni A. Emerging biomaterial-based strategies for personalized therapeutic in situ cancer vaccines.Biomaterials. 2022; 280121297Crossref PubMed Scopus (26) Google Scholar The NanoLymph is a 3-dimensional (3D) printable nanofluidic implant designed for subcutaneous deployment with dual refillable reservoirs, each for sustained immunomodulator elution and antigen or cell presentation. The small scale (∼8 mm in diameter and 2 mm in thickness) "D-shaped" agnostic platform offers flexibility for use of a wide spectrum of immunomodulatory agents and antigens. When the reservoirs are each loaded with GM-CSF and resiquimod (a Toll-like receptor 7/8 agonist) as well as a peptide antigen, dendritic cells (DCs) are recruited on site and activated as antigen-presenting cells (APCs). Thereafter, the activated DCs migrate to the lymph nodes to initiate an antigen-specific T-cell response. The versatility in immunomodulators, antigens, and/or cells loaded will permit the orchestration of a targeted immune cell–mediated response across a range of chronic diseases, acting as an in situ therapeutic or prophylactic vaccine with clear applicability to cancer and infectious diseases. In the context of infectious diseases, various antigens can be adopted to generate immunity against specific pathogens. In the context of cancer, autologous whole tumor cell lysates are used as an antigen source, facilitating the generation of an immune response directed toward the unique antigenic repertoire in the patient's own tumor.10Diao L. Liu M. Rethinking antigen source: cancer vaccines based on whole tumor cell/tissue lysate or whole tumor cell.Adv Sci. 2023; 102300121Crossref Scopus (13) Google Scholar Of note, the site of deployment may be crucial in generating potent immune activation. In this context, peritumoral implantation may be more effective than a distal subcutaneous site, although such placement would compromise the accessibility for antigen and adjuvant loading and refilling. The refillability aspect of the technology is advantageous for long-term treatment. Other platforms, including biodegradable polymers, nanoparticle systems, and microencapsulation, have been designed to gradually release vaccine components (antigens and adjuvants) against various pathogens, ensuring sustained immunization.11Kerr M.D. Johnson W.T. McBride D.A. Chumber A.K. Shah N.J. Biodegradable scaffolds for enhancing vaccine delivery.Bioeng Transl Med. 2023; 8e10591Crossref Scopus (1) Google Scholar,12Roth G.A. Picece V.C.T.M. Ou B.S. Luo W. Pulendran B. Appel E.A. Designing spatial and temporal control of vaccine responses.Nat Rev Mater. 2022; 7: 174-195Crossref PubMed Scopus (114) Google Scholar Compared with traditional vaccines, these systems have shown an enhanced immune response with fewer doses, which makes them particularly relevant in resource-limited areas. However, the challenges include limited stability and viability of vaccine components, precise control of release rates, and the need for extensive testing and development. An alternative form of immunomodulation, adoptive T-cell therapy, engineers T cells ex vivo to target tumor antigens in vivo. However, after reinfusion, only a small fraction of the engineered T cells actually reach the tumor, where they encounter difficulty penetrating the tumor mass.13Zhang A.Q. Hostetler A. Chen L.E. Mukkamala V. Abraham W. Padilla L.T. et al.Universal redirection of CAR T cells against solid tumours via membrane-inserted ligands for the CAR.Nat Biomed Eng. 2023; 7: 1113-1128Crossref PubMed Scopus (9) Google Scholar More importantly, the heterogeneity of tumor surface antigens increases as it proliferates, resulting in short-lived responses to adoptive T-cell therapy. To address these challenges, an immune engineered biomaterials–based platform, termed synergistic in situ vaccination enhanced T-cell depot (SIVET), was developed.14Adu-Berchie K. Brockman J.M. Liu Y. To T.W. Zhang D.K.Y. Najibi A.J. et al.Adoptive T cell transfer and host antigen-presenting cell recruitment with cryogel scaffolds promotes long-term protection against solid tumors.Nat Commun. 2023; 14: 3546Crossref PubMed Scopus (6) Google Scholar The SIVET platform advances beyond previous in situ vaccination work centered solely on DCs. Composed of an alginate-collagen hybrid cryogel, the SIVET allows intratumoral controlled release of adoptively transferred T cells and immunostimulants to attract APCs. The T-cell depot facilitates tumor debulking, in which dying cancer cells serve as the antigen source. Simultaneous local release of GM-CSF or FMS-like tyrosine kinase 3 ligand (FLT3L) and CpG stimulates continual APC recruitment and activation, respectively. This synergistic in situ vaccination approach enables protection against tumor antigen escape and long-term T-cell activation, representing an innovative intervention for long-acting immunomodulation. Transplant patients rely on viable allografts to restore dysfunctional organs or tissues. This is the case for both cell and organ transplantation. However, host immune rejection remains a barrier to widespread clinical adoption. Graft rejection results in the destruction of transplanted tissues, triggered by even the slight mismatches in HLA alleles. As such, systemic immunosuppressive regimens are commonly used to avoid rejection. Unfortunately, these agents are associated with severe adverse effects and increased risks of infections, neoplasms, and organ damage. To address this challenge, numerous approaches have been developed to achieve local immune modulation, sparing the body from the deleterious effect of lifelong immune suppression.15Chua C.Y.X. Jiang A.Y. Eufrásio-da-Silva T. Dolatshahi-Pirouz A. Langer R. Orive G. et al.Emerging immunomodulatory strategies for cell therapeutics.Trends Biotechnol. 2023; 41: 358-373Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar These include minimizing immunogenicity of transplanted cells via clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated protein 9 (Cas9) genome editing; leveraging RNA therapeutics and cytokine delivery to induce immune tolerance; local cotransplantation with immunomodulatory cells such as T reg cells, Sertoli cells, and mesenchymal stem cells; and local delivery of immunomodulatory agents.15Chua C.Y.X. Jiang A.Y. Eufrásio-da-Silva T. Dolatshahi-Pirouz A. Langer R. Orive G. et al.Emerging immunomodulatory strategies for cell therapeutics.Trends Biotechnol. 2023; 41: 358-373Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar These approaches share the need for suitable technologies to generate an ideal site for cell transplantation that achieves cell retention while providing sustained modulation of the tissue immune microenvironment. One such platform, termed NICHE, is a dual-reservoir 3D-printed nylon implant designed for subdermal transplantation of pancreatic islets for the management of type 1 diabetes (T1D). In their native microenvironment, islets are densely vascularized via intraislet capillaries, and they obtain approximately 20% of the pancreatic blood supply. Following implantation, the NICHE relies on the angiogenic properties of mesenchymal stem cells to generate a dense blood vessel network capable of supplying oxygen, nutrients, and rapid glucose and insulin exchange suitable for the long-term viability and function of pancreatic islets.16Paez-Mayorga J. Capuani S. Farina M. Lotito M.L. Niles J.A. Salazar H.F. et al.Enhanced in vivo vascularization of 3D-printed cell encapsulation device using platelet-rich plasma and mesenchymal stem cells.Adv Healthc Mater. 2020; 9e2000670PubMed Google Scholar Immune rejection is prevented via local sustained delivery of immunosuppressants such as thymoglobulin, cytotoxic T lymphocyte–associated antigen-4 (CTLA-4) immunoglobulin, and anti-CD40-L, which have the function of depleting or impeding activation of the costimulatory pathway for T cells, respectively. Notably, the NICHE allows for transcutaneous reloading of the drug reservoir, extending functionality over the long term. In this context, the platform allows for the use of different agents (eg, growth factors, immunoadjuvants, cytokines) alone or in combination, as well as for their simultaneous or sequential delivery to support transplanted cells during the phases of engraftment and local tissue remodeling. In an allogenic pancreatic islet transplantation model, in immunocompetent diabetic rats, the NICHE achieved T1D reversal with no sign of systemic immunosuppression or adverse effects throughout the 180 days of analysis.17Paez-Mayorga J. Campa-Carranza J.N. Capuani S. Hernandez N. Liu H.-C. Chua C.Y.X. et al.Implantable niche with local immunosuppression for islet allotransplantation achieves type 1 diabetes reversal in rats.Nature Communications. 2022; 13: 7951Crossref PubMed Scopus (11) Google Scholar Local immune modulation can also be achieved via codelivery of immune adjuvant–releasing microparticles or gels with transplanted cells.18Wang X. Brown N.K. Wang B. Shariati K. Wang K. Fuchs S. et al.Local immunomodulatory strategies to prevent allo-rejection in transplantation of insulin-producing cells.Advanced Science. 2021; 82003708Google Scholar As a notable example, FasL-modified microgels conferred long-term immune protection to pancreatic islet allografts co.transplanted in non.human primates. Here, the Fas receptor/Fas ligand (FasL) pathway was leveraged to confer immune privilege and tolerance to self-antigens by inducing apoptosis in infiltrating lymphocytes and inflammatory cells.19Lei J. Coronel M.M. Yolcu E.S. Deng H. Grimany-Nuno O. Hunckler M.D. et al.FasL microgels induce immune acceptance of islet allografts in nonhuman primates.Sci Adv. 2022; 8eabm9881Crossref Scopus (29) Google Scholar These clinically translatable technologies could be adopted for the transplantation and delivery of cell therapeutics for clinical applications beyond T1D, including neurodegenerative and cardiovascular diseases and pathologies associated with hormone deficiencies. Their adaptability for various agents, flexibility in dosing timing and duration, and ability to localize distribution render these platforms significant in the development of novel immunomodulatory approaches for cell therapeutics. However, given their multicomponent nature, the regulatory approval of these strategies will require complex translational efforts. Allergic disorders affect more than one-third of the population and remain a therapeutic challenge. Although allergen avoidance is an effective method of prevention, it is not always possible, and symptomatic medications may not be adequate. Over the past century, allergen immunotherapy (AIT) has evolved to be an effective antigen-specific treatment for IgE-mediated hypersensitivity disorders.20Durham S.R. Shamji M.H. Allergen immunotherapy: past, present and future.Nat Rev Immunol. 2023; 23: 317-328Crossref PubMed Scopus (75) Google Scholar The conventional AIT strategy for many aeroallergens or stinging insect allergens is the repeated subcutaneous injection of allergen extracts, and more recently, with recombinant allergens, chemically altered allergens (allergoids), or T cell-targeted peptides. Sublingual immunotherapy is efficacious with some aeroallergens, and oral AIT is approved only for peanut allergy desensitization. Epicutaneous, microneedle patch, mRNA vaccine, or intralymphatic immunotherapy strategies are under investigation, and a growing number of additional innovative strategies to improve AIT remain exploratory. These include combining allergen with immunomodulating Toll-like receptor agonists, mAbs against type 2 cytokines, or cytokine receptors. The goal of AIT is to induce antigen-specific tolerance.20Durham S.R. Shamji M.H. Allergen immunotherapy: past, present and future.Nat Rev Immunol. 2023; 23: 317-328Crossref PubMed Scopus (75) Google Scholar Mechanistically, AIT-induced tolerance is manifested by induction of regulatory DCs, regulatory B cells, and regulatory T cells, which produce IL-10 and TGF-β and are capable of inhibiting type 2 TH2 cells and type 2 innate lymphoid cells, hence reducing the number of type 2 cytokines and inducing IgG-blocking antibodies that inhibit the binding of IgE to allergen. Efforts to enhance the tolerance-inducing efficacy and safety of AIT are exploring novel long-acting immunomodulatory delivery platforms such as nanoparticles, microneedle patches,21Paris J.L. Vora L.K. Torres M.J. Mayorga C. Donnelly R.F. Microneedle array patches for allergen-specific immunotherapy.Drug Discov Today. 2023; 28103556Crossref PubMed Scopus (4) Google Scholar and programmable subcutaneous implants for delivery of allergen and immunomodulatory agents. Nanoparticle formulations can be optimized for a variety of physical and chemical factors, including size, pH, antigen loading, and optimal cellular targeting and uptake.22Johnson L. Duschl A. Himly M. Nanotechnology-based vaccines for allergen-specific immunotherapy: potentials and challenges of conventional and novel adjuvants under research.Vaccines (Basel). 2020; 8: 237Crossref PubMed Scopus (28) Google Scholar Importantly, nanoparticle platforms offer the potential for topical, oral, or systemic administration. Murine studies with allergen-loaded nanoparticles support the potential for inducing allergen-specific tolerance.23Hughes K.R. Saunders M.N. Landers J.J. Janczak K.W. Turkistani H. Rad L.M. et al.Masked delivery of allergen in nanoparticles safely attenuates anaphylactic response in murine models of peanut allergy.Front Allergy. 2022; 3829605Crossref PubMed Google Scholar Microneedle patches can be engineered to potentially improve on passive epicutaneous allergen delivery to APCs in the skin, thereby enhancing the tolerance-inducing efficacy of epicutaneous AIT. Murine studies with peanut allergen support the potential for this platform to induce antigen-specific tolerance.24Landers J.J. Janczak K.W. Shakya A.K. Zarnitsyn V. Patel S.R. Baker Jr., J.R. et al.Targeted allergen-specific immunotherapy within the skin improves allergen delivery to induce desensitization to peanut.Immunotherapy. 2022; 14: 539-552Crossref PubMed Scopus (16) Google Scholar There is also potential for implantable microchambers, such as the aforementioned programmable 3D printed NanoLymph platform for potential cancer immunotherapy applications,3Pons-Faudoa F.P. Di Trani N. Capuani S. Campa-Carranza J.N. Nehete B. Sharma S. et al.Long-acting refillable nanofluidic implant confers protection against SHIV infection in nonhuman primates.Science Translational Medicine. 2023; 15eadg2887Crossref PubMed Scopus (6) Google Scholar to be exploited for enhanced AIT. Such an approach would entail subcutaneous implantation of the NanoLymph, in which 1 chamber is allergen loaded and 1 chamber is cytokine loaded with GM-CSF to promote migration and activation of DCs and with IL-10 and TGF-β to promote differentiation of allergen-specific regulatory T cells and allergen-specific tolerance. Overall, the convergence of biologic and engineering strategies is leading to highly innovative approaches for AIT. Such interdisciplinary collaborations are likely to yield novel technological advances for treating allergic disorders in the near future. In conclusion, innovations in drug and antigen-delivery technologies have broadened the spectrum of applicability of immunomodulation for the prevention, management, and treatment of diseases. In this context, long-acting and tunable immunomodulatory approaches can extend disease management duration while simplifying dosing regimen and improving quality of life. As evident in the field of cancer immunotherapy, cell transplantation, and allergy management, the success of long-acting immunomodulatory platforms has the potential to have a long-lasting, transformative impact in clinical care. Notably, these technologies could enhance cost-effectiveness in medical treatments and contribute to health care equity. Enhanced efficacy, reduced drug doses, and lower frequency of administration could not only lower direct treatment costs but also decrease associated health care expenses, such as those related to administration and patient care.