Sustained release hydrogel for durable locoregional chemoimmunotherapy for BRAF-mutated melanoma

The wide prevalence of BRAF mutations in diagnosed melanomas drove the clinical advancement of BRAF inhibitors in combination with immune checkpoint blockade for treatment of advanced disease. However, deficits in therapeutic potencies and safety profiles motivate the development of more effective strategies that improve the combination therapy's therapeutic index. Herein, we demonstrate the benefits of a locoregional chemoimmunotherapy delivery system, a novel thermosensitive hydrogel comprised of gelatin and Pluronic® F127 components already widely used in humans in both commercial and clinical products, for the co-delivery of a small molecule BRAF inhibitor with immune checkpoint blockade antibody for the treatment of BRAF-mutated melanoma. In vivo evaluation of administration route and immune checkpoint target effects revealed intratumoral administration of antagonistic programmed cell death protein 1 antibody (aPD-1) lead to potent antitumor therapy in combination with BRAF inhibitor vemurafenib. The thermosensitive F127-g-Gelatin hydrogel that was evaluated in multiple murine models of BRAF-mutated melanoma that facilitated prolonged local drug release within the tumor (>1 week) substantially improved local immunomodulation, tumor control, rates of tumor response, and animal survival. Thermosensitive F127-g-Gelatin hydrogels thus improve upon the clinical benefits of vemurafenib and aPD-1 in a locoregional chemoimmunotherapy approach for the treatment of BRAF-mutated melanoma.

A dhesion analysis via a tumor vasculature-like microfluidic device identifies CD8+ T cells with enhanced tumor homing to improve cell therapy

CD8⁺ T cell recruitment to the tumor microenvironment is critical for the success of adoptive cell therapy (ACT). Unfortunately, only a small fraction of transferred cells home to solid tumors. Adhesive ligand-receptor interactions have been implicated in CD8⁺ T cell homing; however, there is a lack of understanding of how CD8⁺ T cells interact with tumor vasculature-expressed adhesive ligands under the influence of hemodynamic flow. Here, the capacity of CD8⁺ T cells to home to melanomas is modeled ex vivo using an engineered microfluidic device that recapitulates the hemodynamic microenvironment of the tumor vasculature. Adoptively transferred CD8⁺ T cells with enhanced adhesion in flow in vitro and tumor homing in vivo improve tumor control by ACT in combination with immune checkpoint blockade. These results show that engineered microfluidic devices can model the microenvironment of the tumor vasculature to identify subsets of T cells with enhanced tumor infiltrating capabilities, a key limitation in ACT.

Elicitation of stem-like CD8+ T cell responses via lymph node-targeted chemoimmunotherapy evokes systemic tumor control

Background

Tumor-draining lymph nodes (TdLNs) are critical in the regulation of local and systemic antitumor T cell immunity and are implicated in coordinating responses to immunomodulatory therapies.

Methods

Biomaterial nanoparticles that deliver chemotherapeutic drug paclitaxel to TdLNs were leveraged to explore its effects in combination and immune checkpoint blockade (ICB) antibody immunotherapy to determine the benefit of TdLN-directed chemoimmunotherapy on tumor control.

Results

Accumulation of immunotherapeutic drugs in combination within TdLNs synergistically enhanced systemic T cell responses that led to improved control of local and disseminated disease and enhanced survival in multiple murine breast tumor models.

Conclusions

These findings suggest a previously underappreciated role of secondary lymphoid tissues in mediating effects of chemoimmunotherapy and demonstrate the potential for nanotechnology to unleashing drug synergies via lymph node targeted delivery to elicit improved response of breast and other cancers.

Thermosensitive hydrogel releasing nitric oxide donor and anti-CTLA-4 micelles for anti-tumor immunotherapy

Due to their autosynchronous roles in shaping the anti-tumor immune response, complex immune regulatory networks acting both locally within the tumor microenvironment as well as in its draining lymph nodes play critical roles in the cancer immunotherapy response. We describe herein a thermosensitive co-polymer hydrogel system formed from biocompatible polymers gelatin and Pluronic^® F127 that are widely used in humans to enable the sustained release of a nitric oxide donor and antibody blocking immune checkpoint cytotoxic T-lymphocyte-associated protein-4 for efficient and durable anti-tumor immunotherapy. By virtue of its unique gel formation and degradation properties that sustain drug retention at the tumor tissue site for triggered release by the tumor microenvironment and formation of in situ micelles optimum in size for lymphatic uptake, this rationally designed thermosensitive hydrogel facilitates modulation of two orthogonal immune signaling networks relevant to the regulation of the anti-tumor immune response to improve local and abscopal effects of cancer immunotherapy.

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.

Tumor-draining lymph nodes are survival niches that support T cell priming against lymphatic transported tumor antigen and effects of immune checkpoint blockade in TNBC

Triple negative breast cancer (TNBC) is a significant clinical problem to which immunotherapeutic strategies have been applied with limited success. Using the syngeneic E0771 TNBC mouse model, this work explores the potential for antitumor CD8⁺ T cell immunity to be primed extratumorally in lymphoid tissues and therapeutically leveraged. CD8⁺ T cell viability and responses within the tumor microenvironment (TME) were found to be severely impaired, effects coincident with local immunosuppression that is recapitulated in lymphoid tissues in late stage disease. Prior to onset of a locally suppressed immune microenvironment, however, CD8⁺ T cell priming within lymph nodes (LN) that depended on tumor lymphatic drainage remained intact. These results demonstrate tumor-draining LNs (TdLN) to be lymphoid tissue niches that support the survival and antigenic priming of CD8⁺ T lymphocytes against lymph-draining antigen. The therapeutic effects of and CD8⁺ T cells response to immune checkpoint blockade were furthermore improved when directed to LNs within the tumor-draining lymphatic basin. Therefore, TdLNs represent a unique potential tumor immunity reservoir in TNBC for which strategies may be developed to improve the effects of ICB immunotherapy.

Quality of CD8+ T cell immunity evoked in lymph nodes is compartmentalized by route of antigen transport and functional in tumor context

Revealing the mechanisms that underlie the expansion of antitumor CD8+ T cells that are associated with improved clinical outcomes is critical to improving immunotherapeutic management of melanoma. How the lymphatic system, which orchestrates the complex sensing of antigen by lymphocytes to mount an adaptive immune response, facilitates this response in the context of malignancy is incompletely understood. To delineate the effects of lymphatic transport and tumor-induced lymphatic and lymph node (LN) remodeling on the elicitation of CD8+ T cell immunity within LNs, we designed a suite of nanoscale biomaterial tools enabling the quantification of antigen access and presentation within the LN and resulting influence on T cell functions. The expansion of antigen-specific stem-like and cytotoxic CD8+ T cell pools was revealed to be sensitive to the mechanism of lymphatic transport to LNs, demonstrating the potential for nanoengineering strategies targeting LNs to optimize cancer immunotherapy in eliciting antitumor CD8+ T cell immunity.

Lymphatic immunomodulation using engineered drug delivery systems for cancer immunotherapy

Though immunotherapy has revolutionized the treatment of cancer to improve disease outcomes, an array of challenges remain that limit wider clinical success, including low rate of response and immune-related adverse events. Targeting immunomodulatory drugs to therapeutically relevant tissues offers a way to overcome these challenges by potentially enabling enhanced therapeutic efficacy and decreased incidence of side effects. Research highlighting the importance of lymphatic tissues in the response to immunotherapy has increased interest in the application of engineered drug delivery systems (DDSs) to enable specific targeting of immunomodulators to lymphatic tissues and cells that they house. To this end, a variety of DDS platforms have been developed that enable more efficient uptake into lymphatic vessels and lymph nodes to provide targeted modulation of the immune response to cancer. This can occur either by delivery of immunotherapeutics to lymphatics tissues or by direct modulation of the lymphatic vasculature itself due to their direct involvement in tumor immune processes. This review will highlight DDS platforms that, by enabling the activities of cancer vaccines, chemotherapeutics, immune checkpoint blockade (ICB) antibodies, and anti- or pro-lymphangiogenic factors to lymphatic tissues through directed delivery and controlled release, augment cancer immunotherapy.

Augmenting the synergies of chemotherapy and immunotherapy through drug delivery

Despite the recent approvals of multiple cancer immunotherapies, low tumor immunogenicity and immunosuppressive tumor microenvironments prevent a large portion of patients from responding to these treatment modalities. Given the immunomodulatory and adjuvant effects of conventional chemotherapy as well as its widespread clinical use, the use of chemotherapy in combination with immunotherapy (so-called chemoimmunotherapy) is an attractive approach to potentiate the effects of immunotherapy in more patient populations. However, due to the limited extent of tumor accumulation, poorly controlled interactions with the immune system, and effects on systemic healthy tissues by chemotherapeutic drugs, the incorporation of anti-cancer agents into biomaterial-based structures, such as nanocarriers, is highly attractive to improve the safety and efficacy of chemoimmunotherapy. Herein, we review the recent progress in drug delivery systems (DDSs) for potentiating the immunomodulatory effects of chemotherapeutics in chemoimmunotherapy, which represent among the most promising next generation strategies for cancer treatment in the immunotherapy era. STATEMENT OF SIGNIFICANCE: Given the benefits of cancer immunotherapy in inducing durable, albeit low rates, of patient response, interest in the immunomodulatory and adjuvant effects of conventional chemotherapy has been re-invigorated. This review article discusses the recent progress towards understanding the synergies between these two treatment types, how they can be used in combination (so-called chemoimmunotherapy), and the potential for drug delivery systems to optimize their effects in translational settings.