Imidazoquinolines with improved pharmacokinetic properties induce a high IFNα to TNFα ratio in vitro and in vivo

Expeditious and environmentally benign synthesis of imidazo[4,5,1-ij]quinolines via sequential Povarov reaction/reductive cyclization

In this contribution, a novel, simple, diastereoselective and environmentally benign two-step diversity-oriented synthesis of imidazo[4,5,1-ij]quinolines is described for the first time. The synthesis of the target compounds involves a deep eutectic solvent-mediated one-pot Povarov reaction leading to the obtention of 8-nitrotetrahydroquinolines, followed by a microwave-assisted reductive cyclocondensation employing different aromatic and aliphatic aldehydes. The target compounds were obtained in up to 70% overall yield starting from commercially available o-nitroanilines, natural phenylpropanoids (trans-anethole and trans-isoeugenol) and aromatic or aliphatic aldehydes. The eutectic solvent employed in the first step was reused in four runs without observing a drastic decrease in catalytic activity, and sodium dithionite showed to be an efficient and green reducing agent for the second step. This methodology provides significant advantages in terms of synthetic and green chemistry such as mild reaction conditions, short reaction time, energy-efficiency, simple work-up procedure, low cost, scalability and utilization of renewable substrates and a reusable solvent.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants. Many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K2, which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K2 50:50 with the unfunctionalized K2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K2 produces a robust Th2 immune response and an antigen-specific Th1 immune response superior to alum, a widely used vaccine adjuvant. Together, these results suggest that K2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

All-Natural Gelatin-Based Nanoemulsion Loaded with TLR 7/8 Agonist for Efficient Modulation of Macrophage Polarization for Immunotherapy

Macrophages are multifunctional immune cells essential for both innate and adaptive immune responses. Tumor-associated macrophages (TAMs) often adopt a tumor-promoting M2-like phenotype, aiding tumor progression and immune evasion. Reprogramming TAMs to a tumoricidal M1-like phenotype is an emerging target for cancer immunotherapy. Resiquimod, a TLR7/8 agonist, can repolarize macrophages from the M2- to M1-like phenotype but is limited by poor solubility. We developed a gelatin nanoemulsion for the loading and delivery of resiquimod, utilizing eugenol oil as the liquid phase and riboflavin-crosslinked gelatin as a scaffold. These nanoemulsions showed high stability, low toxicity, and effective macrophage repolarization, significantly enhancing pro-inflammatory markers and anticancer activity in co-culture models.

Resiquimod-loaded cationic liposomes cure mice with peritoneal carcinomatosis and induce specific anti-tumor immunity

Peritoneal carcinomatosis (PC) is characterized by a high recurrence rate and mortality following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC), primarily due to incomplete cancer elimination. To enhance the standard of care for PC, we developed two cationic liposomal formulations aimed at localizing a toll-like receptor agonist, resiquimod (R848), in the peritoneal cavity to activate the immune system locally to specifically eradicate residual tumor cells. These formulations effectively extended R848 retention in the peritoneum by >10-fold, resulting in up to a 2-fold increase in interferon α (IFN-α) induction in the peritoneal fluid, without increasing the plasma levels. In a CT26 colon cancer model with peritoneal metastases, these liposomal R848 formulations, when combined with oxaliplatin (OXA)-an agent used in HIPEC that induces immunogenic cell death-increased tumor infiltration of effector immune cells, including DCs, CD4, and CD8 T cells. This led to the complete elimination of PC in 60-70% of the mice, while the control mice reached humane endpoints by 30 days. The cured mice developed specific antitumor immunity, as re-challenging them with the same tumor cells did not result in tumor establishment. However, inoculation with a different tumor line led to tumor development. Additionally, exposing CT26 tumor antigens to the splenocytes isolated from the cured mice induced the expansion of CD4 and CD8 T cells and the release of IFN-γ, demonstrating long-term immune memory to the specific tumor. The anti-tumor efficacy of these liposomal R848 formulations was mediated via CD8 T cells with different levels of involvement of CD4 and B cells, and the combination with an anti-PD-1 antibody achieved a cure rate of 90%.

Exploring in vivo combinatorial chemo-immunotherapy: Addressing p97 suppression and immune reinvigoration in pancreatic cancer with tumor microenvironment-responsive nanoformulation

Pancreatic ductal adenocarcinoma (PDAC) has an extremely devastating nature with poor prognosis and increasing incidence, making it a formidable challenge in the global fight against cancer-related mortality. In this innovative preclinical investigation, the VCP/p97 inhibitor CB-5083 (CB), miR-142, a PD-L1 inhibitor, and immunoadjuvant resiquimod (R848; R) were synergistically encapsulated in solid lipid nanoparticles (SLNs). These SLNs demonstrated features of peptides targeting PD-L1, EGFR, and the endoplasmic reticulum, enclosed in a pH-responsive polyglutamic (PGA)-polyethylene glycol (PEG) shell. The homogeneous size and zeta potential of the nanoparticles were stable for 28 days at 4°C. The study substantiated the concurrent modulation of key pathways by the CB, miR, and R-loaded nanoformulation, prominently affecting VCP/Bip/ATF6, PD-L1/TGF-β/IL-4, -8, -10, and TNF-α/IFN-γ/IL-1, -12/GM-CSF/CCL4 pathways. This adaptable nanoformulation induced durable antitumor immune responses and inhibited Panc-02 tumor growth by enhancing T cell infiltration, dendritic cell maturation, and suppressing Tregs and TAMs in mice bearing Panc-02 tumors. Furthermore, tissue distribution studies, biochemical assays, and histological examinations highlighted enhanced safety with PGA and peptide-modified nanoformulations for CB, miR, and/or R in Panc-02-bearing mice. This versatile nanoformulation allows tailored adjustment of the tumor microenvironment, thereby optimizing the localized delivery of combined therapy. These compelling findings advocate the potential development of a pH-sensitive, three-in-one PGA-PEG nanoformulation that combines a VCP inhibitor, a PD-L1 inhibitor, and an immunoadjuvant for cancer treatment via combinatorial chemo-immunotherapy.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants, though many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K 2 , which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K 2 50:50 with the unfunctionalized K 2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP, while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K 2 produces antigen-specific IgG titers that were statistically similar to alum, the gold standard adjuvant, and a significantly lower ratio of Th2-associated IgG1 to Th1-associated IgG2a than alum, suggesting a more balanced Th1 and Th2 response. Together, these results suggest that K 2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Table of Contents

Activation of toll-like receptors (TLRs) stimulates a signaling cascade to induce an immune response. A TLR7 agonist was conjugated to an injectable peptide hydrogel, which was then used to deliver a model vaccine antigen. This platform produced antibody titers similar to the gold standard adjuvant alum and demonstrated an improved balance between Th1- and Th2-mediated immunity over alum.