Aptamer-Targeted Attenuation of IL-2 Signaling in CD8+ T Cells Enhances Antitumor Immunity.

Immune responses elicited against cancer using existing therapies such as vaccines or immune stimulatory antibodies are often not curative. One way to potentiate antitumor immunity is to enhance the long-term persistence of anti-tumor CD8+ T cells. Studies have shown that the persistence of activated CD8+ T cells is negatively impacted by the strength of interleukin 2 (IL-2) signaling. Here, we used small interfering RNAs (siRNAs) against CD25 (IL-2Rα) to attenuate IL-2 signaling in CD8+ T cells. The siRNAs were targeted to 4-1BB-expressing CD8+ T cells by conjugation to a 4-1BB-binding oligonucleotide aptamer. Systemic administration of the 4-1BB aptamer-CD25 siRNA conjugate downregulated CD25 mRNA only in 4-1BB-expressing CD8+ T cells promoting their differentiation into memory cells. Treatment with the 4-1BB aptamer-CD25 siRNA conjugates enhanced the antitumor response of a cellular vaccine or local radiation therapy. Indicative of the generality of this approach, 4-1BB aptamer-targeted delivery of an Axin-1 siRNA, a rate-limiting component of the ß-catenin destruction complex, enhanced CD8+ T cell memory development and antitumor activity. These findings show that aptamer-targeted siRNA therapeutics can be used to modulate the function of circulating CD8+ T cells, skewing their development into long-lasting memory CD8+ T cells, and thereby potentiating antitumor immunity.

A TIM-3 Oligonucleotide Aptamer Enhances T Cell Functions and Potentiates Tumor Immunity in Mice.

T cell immunoglobulin-3 (TIM-3) is a negative regulator of interferon-γ (IFN-γ) secreting CD4+ T cells and CD8+ T cytotoxic cells. Recent studies have highlighted the role of TIM-3 as an important mediator of CD8+ T cell exhaustion in the setting of chronic viral infections and cancer. In murine tumor models, antibody blockade of TIM-3 with anti-TIM-3 antibodies as monotherapy has no or minimal antitumor activity, suggesting that TIM-3 signaling exerts an accessory or amplifying effect in keeping immune responses in check. Using a combined bead and cell-based systemic evolution of ligands by exponential enrichment (SELEX) protocol, we have isolated nuclease-resistant oligonucleotide aptamer ligands that bind to cell-associated TIM-3 with high affinity and specificity. A trimeric form of the TIM-3 aptamer blocked the interaction of TIM-3 with Galectin-9, reduced cell death, and enhanced survival, proliferation, and cytokine secretion in vitro. In tumor-bearing mice, the aptamer delayed tumor growth as monotherapy and synergized with PD-1 antibody in prolonging the survival of the tumor-bearing mice. Both in vitro and in vivo, the trimeric aptamer displayed superior activity compared to the currently used RMT3-23 monoclonal antibody. This study suggests that multi-valent aptamers could represent an alternative platform to generate potent ligands to manipulate the function of TIM-3 and other immune modulatory receptors.

Characterizing Gender Eligibility Descriptions for Clinical Trials Registered on ClinicalTrials.gov.

This cross-sectional, exploratory study uses ClinicalTrials.gov data from trials initiated on or after January 18, 2017, to characterize the use of a new free-text "gender eligibility description" data field; reports the frequency of gender identity terms used; and assesses the correct or incorrect use of the field.

Comparison of Availability of Trial Results in ClinicalTrials.gov and PubMed by Data Source and Funder Type.

This study examines the dissemination of trial results by data source (ie, ClinicalTrials.gov and PubMed) and funder type (ie, industry and nonindustry).

Immunomodulation of T- and NK-cell Responses by a Bispecific Antibody Targeting CD28 Homolog and PD-L1.

Checkpoint blockade therapies targeting PD-1/PD-L1 and CTLA-4 are clinically successful but also evoke adverse events due to systemic T-cell activation. We engineered a bispecific, mAb targeting CD28 homolog (CD28H), a newly identified B7 family receptor that is constitutively expressed on T and natural killer (NK) cells, with a PD-L1 antibody to potentiate tumor-specific immune responses. The bispecific antibody led to T-cell costimulation, induced NK-cell cytotoxicity of PD-L1-expressing tumor cells, and activated tissue-resident memory CD8+ T cells. Mechanistically, the CD28H agonistic arm of the bispecific antibody reduced PD-L1/PD-1-induced SHP2 phosphorylation while simultaneously augmenting T-cell receptor signaling by activating the MAPK and AKT pathways. This bispecific approach could be used to target multiple immune cells, including CD8+ T cells, tissue-resident memory T cells, and NK cells, in a tumor-specific manner that may lead to induction of durable, therapeutic antitumor responses.

Potentiating tumor immunity using aptamer-targeted RNAi to render CD8+ T cells resistant to TGFß inhibition.

TGFß secreted by tumor cells and/or tumor infiltrating stromal cells is a key mediator of tumor growth and immune suppression at the tumor site. Nonetheless, clinical trials in cancer patients targeting the TGFß pathway exhibited at best a modest therapeutic benefit. A likely reason, a common limitation of many cancer drugs, is that the physiologic roles of TGFß in tissue homeostasis, angiogenesis, and immune regulation precluded the dose escalation necessary to achieve a profound clinical response. Murine studies have suggested that countering immune suppressive effects of TGFß may be sufficient to inhibit tumor growth. Here we describe an approach to render vaccine-activated CD8+ T cells transiently resistant to TGFß inhibition using an siRNA against Smad4 to inhibit a key step in the canonical TGFß signaling pathway. The siRNA was targeted to vaccine activated CD8+ T cells in the mouse by conjugation to a 4-1BB binding oligonucleotide (ODN) aptamer ligand (4-1BB-Smad4 conjugate). In vitro the 4-1BB-Smad4 conjugate rendered T cells partially resistant to TGFß inhibition, and treatment of tumor bearing mice with systemically administered 4-1BB-Smad4 conjugate enhanced vaccine- and irradiation-induced antitumor immunity. Limiting the inhibitory effects of TGFß to tumor-specific T cells will not interfere with its multiple physiologic roles and hence reduce the risk of toxicity.

Cross-Coupling Biarylation of Nitroaryl Chlorides Through High Speed Ball Milling.

Solvent-free reaction using a high-speed ball milling technique has been applied to the classical Ullmann coupling reaction. Cross-coupling biarylation of several nitroaryl chlorides was achieved in good yields when performed in custom-made copper vials through continuous shaking without additional copper or solvent. Cross-coupling products were obtained almost pure and NMR-ready. These reactions were cleaner than solution phase coupling which require longer reaction time in high boiling solvents, and added catalysts as well as lengthy extraction and purification steps. Gram quantities of cross biaryl compounds have been synthesized with larger copper vials, a proof that this method can be used to reduce industrial waste and for sustainability.

Regulation of T-type calcium channel expression by sodium butyrate in prostate cancer cells.

Several cellular mechanisms contribute to the neuroendocrine differentiation of prostate cancer cells, including exposure to sodium butyrate (NaBu), a naturally occurring salt of the short chain fatty acid n-butyric acid. NaBu belongs to a class of histone deacetylase inhibitors with potential anticancer function. T-type calcium channel expression constitutes an important route for calcium influx in tumor cells that may trigger changes in cell proliferation and differentiation. In this work we investigated the role NaBu on the differentiation of lymph node carcinoma of the prostate (LNCaP) cells and its effect on T-type Ca(2+) channel expression. NaBu stimulates the morphological and molecular differentiation of LNCaP cells. Stimulation of LNCaP cells with NaBu evokes a significant increase in the expression of the Cav3.2 T-type channel subunits. Furthermore, the increased Cav3.2 expression promotes membrane insertion of T-type Ca(2+) channels capable of generating fast inactivating Ca(2+) currents, sensitive to 100µM Ni(2+) ions. Inhibition of T-type Ca(2+) channel function reduces the outgrowth of neurite-like processes in LNCaP cells. NaBu-evoked expression of T-type Ca(2+) channels is also involved in the regulation of cell viability. Inhibition of T-type Ca(2+) channels causes a significant reduction in the viability of LNCaP cells treated with 1mM NaBu, suggesting that Ca(2+) influx via T-type channels can promote cell proliferation. However, increased expression of T-type Ca(2+) channels enhanced the cytotoxic effect of thapsigargin and paclitaxel on cell proliferation. These findings demonstrate that NaBu stimulates T-type Ca(2+) channel expression, thereby regulating both the morphological differentiation and growth of prostate cancer cells.