Drug-eluting immune checkpoint blockade antibody-nanoparticle conjugate enhances locoregional and systemic combination cancer immunotherapy through T lymphocyte targeting.

Multiple small molecule immune modulators have been identified as synergistic with immune checkpoint blockade (ICB) in their effects on T lymphocytes, but are limited in their successful application to combination cancer immunotherapy due to their short in vivo retention and lack of affinity for T cells. We engineered an antibody-nanoparticle conjugate (ANC) platform consisting of 30 nm polymer nanoparticles that, due to their size and formulation, efficiently distribute after administration to lymph nodes, tissues highly enriched in lymphocytes that contribute to tumor control mediated by ICB. Displaying monoclonal antibodies against surface-expressed T cell markers, NP delivery in vivo to circulating and lymph node-resident lymphocytes was substantially enhanced, as was delivery of small molecules formulated into the NP by passive encapsulation. Using ICB monoclonal antibodies as both targeting moiety and signal-blocking therapeutic, ANCs improved the local and systemic anti-tumor effects of small molecule TGFß receptor 1 inhibitor and an adenosine 2A antagonist when administered either locoregionally or systemically into the circulation in two syngeneic, aggressive tumor models, slowing tumor growth and prolonging animal survival. As these benefits were lost in the absence of ANC targeting, co-formulation strategies enabling the targeted co-delivery of multiple immunotherapeutics to T lymphocytes have high potential to improve ICB cancer immunotherapy by concurrent inhibition of non-redundant suppressive pathways.

Quantitation of lymphatic transport mechanism and barrier influences on lymph node-resident leukocyte access to lymph-borne macromolecules and drug delivery systems.

Lymph nodes (LNs) are tissues of the immune system that house leukocytes, making them targets of interest for a variety of therapeutic immunomodulation applications. However, achieving accumulation of a therapeutic in the LN does not guarantee equal access to all leukocyte subsets. LNs are structured to enable sampling of lymph draining from peripheral tissues in a highly spatiotemporally regulated fashion in order to facilitate optimal adaptive immune responses. This structure results in restricted nanoscale drug delivery carrier access to specific leukocyte targets within the LN parenchyma. Herein, a framework is presented to assess the manner in which lymph-derived macromolecules and particles are sampled in the LN to reveal new insights into how therapeutic strategies or drug delivery systems may be designed to improve access to dLN-resident leukocytes. This summary analysis of previous reports from our group assesses model nanoscale fluorescent tracer association with various leukocyte populations across relevant time periods post administration, studies the effects of bioactive molecule NO on access of lymph-borne solutes to dLN leukocytes, and illustrates the benefits to leukocyte access afforded by lymphatic-targeted multistage drug delivery systems. Results reveal trends consistent with the consensus view of how lymph is sampled by LN leukocytes resulting from tissue structural barriers that regulate inter-LN transport and demonstrate how novel, engineered delivery systems may be designed to overcome these barriers to unlock the therapeutic potential of LN-resident cells as drug delivery targets.

Blockade of immune checkpoints in lymph nodes through locoregional delivery augments cancer immunotherapy.

Systemic administration of immune checkpoint blockade (ICB) monoclonal antibodies (mAbs) can unleash antitumor functions of T cells but is associated with variable response rates and off-target toxicities. We hypothesized that antitumor efficacy of ICB is limited by the minimal accumulation of mAb within tissues where antitumor immunity is elicited and regulated, which include the tumor microenvironment (TME) and secondary lymphoid tissues. In contrast to systemic administration, intratumoral and intradermal routes of administration resulted in higher mAb accumulation within both the TME and its draining lymph nodes (LNs) or LNs alone, respectively. The use of either locoregional administration route resulted in pronounced T cell responses from the ICB therapy, which developed in the secondary lymphoid tissues and TME of treated mice. Targeted delivery of mAb to tumor-draining lymph nodes (TdLNs) alone was associated with enhanced antitumor immunity and improved therapeutic effects compared to conventional systemic ICB therapy, and these effects were sustained at reduced mAb doses and comparable to those achieved by intratumoral administration. These data suggest that locoregional routes of administration of ICB mAb can augment ICB therapy by improving immunomodulation within TdLNs.

Publisher Correction: Programmable multistage drug delivery to lymph nodes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Programmable multistage drug delivery to lymph nodes.

Therapeutic delivery selectively to lymph nodes has the potential to address a variety of unmet clinical needs. However, owing to the unique structure of the lymphatics and the size-restrictive nature of the lymph node reticular network, delivering cargo to specific cells in the lymph node cortex and paracortex is difficult. Here, we describe a delivery system to overcome lymphatic and intra-lymph node transport barriers by combining nanoparticles that are rapidly conveyed to draining lymph nodes after administration in peripheral tissues with programmable degradable linkers. This platform enables the controlled release of intra-lymph-mobile small-molecular cargo, which can reach vastly more immune cells throughout the lymph node than either the particles or free compounds alone. The release rate can be programmed, allowing access to different lymph node structures and therefore specific lymphocyte subpopulations. We are thus able to alter the subtypes of drugged lymph node cells to improve immunotherapeutic effects.

Material design for lymph node drug delivery.

A significant fraction of the total immune cells in the body are located in several hundred lymph nodes, in which lymphocyte accumulation, activation and proliferation are organized. Therefore, targeting lymph nodes provides the possibility to directly deliver drugs to lymphocytes and lymph node-resident cells and thus to modify the adaptive immune response. However, owing to the structure and anatomy of lymph nodes, as well as the distinct localization and migration of the different cell types within the lymph node, it is difficult to access specific cell populations by delivering free drugs. Materials can be used as instructive delivery vehicles to achieve accumulation of drugs in the lymph nodes and to target specific lymph node-resident cell subtypes. In this Review, we describe the compartmental architecture of lymph nodes and the cell and fluid transport mechanisms to and from lymph nodes. We discuss the different entry routes into lymph nodes and how they can be explored for drug delivery, including the lymphatics, blood capillaries, high endothelial venules, cell-mediated pathways, homing of circulating lymphocytes and direct lymph node injection. We examine different nanoscale and microscale materials for the targeting of specific immune cells and highlight their potential for the treatment of immune dysfunction and for cancer immunotherapy. Finally, we give an outlook to the field, exploring how lymph node targeting can be improved by the use of materials.

Winner of the society for biomaterials young investigator award for the annual meeting of the society for biomaterials, April 11-14, 2018, Atlanta, GA: S-nitrosated poly(propylene sulfide) nanoparticles for enhanced nitric oxide delivery to lymphatic tissues.

Nitric oxide (NO) is a therapeutic implicated for the treatment of diseases afflicting lymphatic tissues, which range from infectious and cardiovascular diseases to cancer. Existing technologies available for NO therapy, however, provide poor bioactivity within lymphatic tissues. In this work, we address this technology gap with a NO encapsulation and delivery strategy leveraging the formation of S-nitrosothiols on lymphatic-targeting pluronic-stabilized, poly(propylene sulfide)-core nanoparticles (SNO-NP). We evaluated in vivo the lymphatic versus systemic delivery of NO resulting from intradermal administration of SNO-NP benchmarked against a commonly used, commercially available small molecule S-nitrosothiol NO donor, examined signs of toxicity systemically as well as localized to the site of injection, and investigated SNO effects on lymphatic transport and NP uptake by lymph node (LN)-resident cells. Donation of NO from SNO-NP, which scaled in proportion to the total administered dose, enhanced LN accumulation by two orders of magnitude without substantially reducing lymphatic transport of NP or the viability and extent of NP uptake by LN-resident cells. Additionally, NO delivery by SNO-NP was accompanied by low-to-negligible NO accumulation in systemic tissues with no apparent inflammation. These results suggest the utility and selectivity of SNO-NP for the targeted treatment of NO-regulated diseases that afflict lymphatic tissues. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1463-1475, 2018.

A rapid method for determining protein diffusion through hydrogels for regenerative medicine applications.

Hydrogels present versatile platforms for the encapsulation and delivery of proteins and cells for regenerative medicine applications. However, differences in hydrogel cross-linking density, polymer weight content, and affinity for proteins all contribute to diverse diffusion rates of proteins through hydrogel networks. Here, we describe a simple method to accurately measure protein diffusion through hydrogels, within a few hours and without the use of large amounts of protein. We tracked the diffusion of several proteins of varying molecular weights along the axial direction of capillary tubes filled with alginate, collagen, or poly(ethylene glycol) hydrogels. The rate of protein diffusion decreased with increasing molecular weight. A computational model of protein diffusion through capillary tubes was also created to predict and verify experimental protein diffusion coefficients. This in vitro capillary tube-based method of measuring protein diffusion represents a simple strategy to interrogate protein diffusion through natural and synthetic hydrogels and aid in the design of better biomaterial-based delivery vehicles that can effectively modulate protein release.

S-Nitrosated Polypropylene Sulfide Nanoparticles for Thiol-Dependent Transnitrosation and Toxicity Against Adult Female Filarial Worms.

A synthetic polymer nanoparticle formulation utilizing the physiological nitrosothiol chemistry for nitric oxide delivery is shown. Toxicity of S-nitroso nanoparticles against adult female Brugia malayi worms, which are responsible for lymphatic filariasis, is dependent on nitric oxide release through transnitrosation as S-nitrosocysteine, a potent endogenous nitric oxide donor.

Overcoming transport barriers for interstitial-, lymphatic-, and lymph node-targeted drug delivery.

Despite drug formulation improving circulation times and targeting, efficacy is stymied by inadequate penetration into and retention within target tissues. This review highlights the barriers restricting delivery to the connective tissue interstitium, lymphatics, and lymph nodes as well as advances in engineering drug carriers to overcome these delivery challenges. Three-dimensional tissue physiology is discussed in the context of providing material design principles for delivery to these tissues; in particular the influence of interstitial and lymphatic flows as well as differential permeabilities of the blood and lymphatic capillaries. Key examples of materials with different characteristics developed to overcome these transport barriers are discussed as well as potential areas for further development.