Versatile Tissue-Injectable Hydrogels with Extended Hydrolytic Release of Bioactive Protein Therapeutics

Hydrogels generally have broad utilization in healthcare due to their tunable structures, high water content, and inherent biocompatibility. FDA-approved applications of hydrogels include spinal cord regeneration, skin fillers, and local therapeutic delivery. Drawbacks exist in the clinical hydrogel space, largely pertaining to inconsistent therapeutic exposure, short-lived release windows, and difficulties inserting the polymer into tissue. In this study, we engineered injectable, biocompatible hydrogels that function as a local protein therapeutic depot with a high degree of user-customizability. We showcase a PEG-based hydrogel functionalized with bioorthogonal strain-promoted azide-alkyne cycloaddition (SPAAC) handles for its polymerization and functionalization with a variety of payloads. Small-molecule and protein cargos, including chemokines and antibodies, were site-specifically modified with hydrolysable "azidoesters" of varying hydrophobicity via direct chemical conjugation or sortase-mediated transpeptidation. These hydrolysable esters afforded extended release of payloads linked to our hydrogels beyond diffusion; with timescales spanning days to months dependent on ester hydrophobicity. Injected hydrogels polymerize in situ and remain in tissue over extended periods of time. Hydrogel-delivered protein payloads elicit biological activity after being modified with SPAAC-compatible linkers, as demonstrated by the successful recruitment of murine T-cells to a mouse melanoma model by hydrolytically released murine CXCL10. These results highlight a highly versatile, customizable hydrogel-based delivery system for local delivery of protein therapeutics with payload release profiles appropriate for a variety of clinical needs.

Abstract 5580: Incorporation of pro-memory transcription factors in fourth generation CARs enhances CAR T cell immunotherapy against solid tumors in an immunocompetent murine model

A major obstacle in current T cell-based immunotherapy against solid tumors is the widely observed T cell exhaustion and loss of functionality within the tumor microenvironment (TME). We, and others, have demonstrated that chronic antigenic signaling is the predominant factor that drives TCR tumor-reactive, and CAR T cell exhaustion in the TME. To combat this exhaustion, we have engineered CD19-targeted third generation CAR constructs to express pro-memory transcription factors associated with longevity, polyfunctionality and/or enhanced responsiveness to immune checkpoint blockade in cancer immunotherapy. Using an immunocompetent murine model of syngeneic solid tumors expressing truncated human-CD19 (hCD19t), we demonstrate that ectopic expression of pro-memory transcription factors in the 4th generation transcription factor-CARs (TF-CARs) augments CAR T cell therapeutic efficacy against solid tumors. Amongst CAR T cells recovered from established solid tumors, the 4th generation TF-CAR T cells retained a memory-precursor effector (MPEC) T cell like phenotype, while the 3rd generation CAR T cells largely displayed a terminally exhausted phenotype (TEx). Importantly, the inclusion of select pro-memory transcription factors did not compromise CAR T cell proliferation or expression of the effector cytokines IFN-γ and TNFα following restimulation. In addition to superior control of primary tumors, the TF-CAR T cells instilled greater long-term protection from tumor relapse in mice, which cleared primary tumors (6/7) compared to 3rd generation CAR T cells (3/7). Collectively, these data present incorporation of pro-memory transcription factors as an attractive engineering strategy to intrinsically combat CAR T cell exhaustion in the TME and promote long-term CAR T cell memory and protection from tumor relapse.

Citation Format: Steven J. Reed, Samantha J. Tower, Ryma Toumi, Vandana Kalia, Surojit Sarkar. Incorporation of pro-memory transcription factors in fourth generation CARs enhances CAR T cell immunotherapy against solid tumors in an immunocompetent murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5580.

IL-18 and Subcapsular Lymph Node Macrophages are Essential for Enhanced B Cell Responses with TLR4 Agonist Adjuvants

Designing modern vaccine adjuvants depends on understanding the cellular and molecular events that connect innate and adaptive immune responses. The synthetic TLR4 agonist glycopyranosyl lipid adjuvant (GLA) formulated in a squalene-in-water emulsion (GLA-SE) augments both cellular and humoral immune responses to vaccine Ags. This adjuvant is currently included in several vaccines undergoing clinical evaluation including those for tuberculosis, leishmaniasis, and influenza. Delineation of the mechanisms of adjuvant activity will enable more informative evaluation of clinical trials. Early after injection, GLA-SE induces substantially more Ag-specific B cells, higher serum Ab titers, and greater numbers of T follicular helper (T_FH) and Th1 cells than alum, the SE alone, or GLA without SE. GLA-SE augments Ag-specific B cell differentiation into germinal center and memory precursor B cells as well as preplasmablasts that rapidly secrete Abs. CD169⁺ SIGNR1⁺ subcapsular medullary macrophages are the primary cells to take up GLA-SE after immunization and are critical for the innate immune responses, including rapid IL-18 production, induced by GLA-SE. Depletion of subcapsular macrophages (SCMф) or abrogation of IL-18 signaling dramatically impairs the Ag-specific B cell and Ab responses augmented by GLA-SE. Depletion of SCMф also drastically reduces the Th1 but not the T_FH response. Thus the GLA-SE adjuvant operates through interaction with IL-18-producing SCMф for the rapid induction of B cell expansion and differentiation, Ab secretion, and Th1 responses, whereas augmentation of T_FH numbers by GLA-SE is independent of SCMф.

Strategic evaluation of vaccine candidate antigens for the prevention of Visceral Leishmaniasis

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes, the most severe of which is visceral leishmaniasis (VL). Vaccination will likely provide the most effective long-term control strategy, as the large number of vectors and potential infectious reservoirs renders sustained interruption of Leishmania parasite transmission extremely difficult. Selection of the best vaccine is complicated because, although several vaccine antigen candidates have been proposed, they have emerged following production in different platforms. To consolidate the information that has been generated into a single vaccine platform, we expressed seven candidates as recombinant proteins in E. coli. After verifying that each recombinant protein could be recognized by VL patients, we evaluated their protective efficacy against experimental L. donovani infection of mice. Administration in formulation with the Th1-potentiating adjuvant GLA-SE indicated that each antigen could elicit antigen-specific Th1 responses that were protective. Considering the ability to reduce parasite burden along with additional factors such as sequence identity across Leishmania species, we then generated a chimeric fusion protein comprising a combination of the 8E, p21 and SMT proteins. This E. coli –expressed fusion protein was also demonstrated to protect against L. donovani infection. These data indicate a novel recombinant vaccine antigen with the potential for use in VL control programs.

From mouse to man: safety, immunogenicity and efficacy of a candidate leishmaniasis vaccine LEISH-F3+GLA-SE

Key antigens of Leishmania species identified in the context of host responses in Leishmania-exposed individuals from disease-endemic areas were prioritized for the development of a subunit vaccine against visceral leishmaniasis (VL), the most deadly form of leishmaniasis. Two Leishmania proteins—nucleoside hydrolase and a sterol 24-c-methyltransferase, each of which are protective in animal models of VL when properly adjuvanted— were produced as a single recombinant fusion protein NS (LEISH-F3) for ease of antigen production and broad coverage of a heterogeneous major histocompatibility complex population. When formulated with glucopyranosyl lipid A-stable oil-in-water nanoemulsion (GLA-SE), a Toll-like receptor 4 T_H1 (T helper 1) promoting nanoemulsion adjuvant, the LEISH-F3 polyprotein induced potent protection against both L. donovani and L. infantum in mice, measured as significant reductions in liver parasite burdens. A robust immune response to each component of the vaccine with polyfunctional CD4 T_H1 cell responses characterized by production of antigen-specific interferon-γ, tumor necrosis factor and interleukin-2 (IL-2), and low levels of IL-5 and IL-10 was induced in immunized mice. We also demonstrate that CD4 T cells, but not CD8 T cells, are sufficient for protection against L. donovani infection in immunized mice. Based on the sum of preclinical data, we prepared GMP materials and performed a phase 1 clinical study with LEISH-F3+GLA-SE in healthy, uninfected adults in the United States. The vaccine candidate was shown to be safe and induced a strong antigen-specific immune response, as evidenced by cytokine and immunoglobulin subclass data. These data provide a strong rationale for additional trials in Leishmania-endemic countries in populations vulnerable to VL.

Squalene emulsion potentiates the adjuvant activity of the TLR4 agonist, GLA, via inflammatory caspases, IL-18, and IFN-γ

The synthetic TLR4 agonist glucopyranosyl lipid adjuvant (GLA) is a potent Th1-response-inducing adjuvant when formulated in a squalene oil-in-water emulsion (SE). While the innate signals triggered by TLR4 engagement are well studied, the contribution of SE remains unclear. To better understand the effect of SE on the adjuvant properties of GLA-SE, we compared the innate and adaptive immune responses elicited by immunization with different formulations: GLA without oil, SE alone or the combination, GLA-SE, in mice. Within the innate response to adjuvants, only GLA-SE displayed features of inflammasome activation, evidenced by early IL-18 secretion and IFN-γ production in memory CD8(+) T cells and neutrophils. Such early IFN-γ production was ablated in caspase-1/11(-/-) mice and in IL-18R1(-/-) mice. Furthermore, caspase-1/11 and IL-18 were also required for full Th1 CD4(+) T-cell induction via GLA-SE. Thus, we demonstrate that IL-18 and caspase-1/11 are components of the response to immunization with the TLR4 agonist/squalene oil-in-water based adjuvant, GLA-SE, providing implications for other adjuvants that combine oils with TLR agonists.

A synthetic adjuvant to enhance and expand immune responses to influenza vaccines

Safe, effective adjuvants that enhance vaccine potency, including induction of neutralizing Abs against a broad range of variant strains, is an important strategy for the development of seasonal influenza vaccines which can provide optimal protection, even during seasons when available vaccines are not well matched to circulating viruses. We investigated the safety and ability of Glucopyranosyl Lipid Adjuvant-Stable Emulsion (GLA-SE), a synthetic Toll-like receptor (TLR)4 agonist formulation, to adjuvant Fluzone® in mice and non-human primates. The GLA-SE adjuvanted Fluzone vaccine caused no adverse reactions, increased the induction of T helper type 1 (T(H)1)-biased cytokines such as IFNγ, TNF and IL-2, and broadened serological responses against drifted A/H1N1 and A/H3N2 influenza variants. These results suggest that synthetic TLR4 adjuvants can enhance the magnitude and quality of protective immunity induced by influenza vaccines.

Cross-protective humoral and cellular immune responses to A/H3N2 drifted influenza viruses following immunization with Fluzone® with a synthetic TLR4 agonist formulation (45.11)

Influenza has a worldwide impact with significant human mortality and economic burden. Although the composition of influenza vaccines is reviewed annually to ensure protection against prevalent influenza strains, antigenically drifted strains emerge after the vaccine composition is decided. Vaccine mismatch reduces vaccine efficacy and produces significant epidemiological consequences. Current licensed vaccines poorly stimulate Th1 anti-influenza cellular responses and provide weak protection against drifted influenza strains not included in the vaccine. We investigated the ability of EM005, a synthetic TLR4 agonist formulated in an oil-in-water emulsion, to adjuvant the Fluzone influenza vaccine. EM005 enhanced the potency of the Fluzone vaccine and broadened its serological protection against drifted A/H3N2 influenza variants compared to vaccination with Fluzone alone or Fluzone formulated with emulsion. Equally important, the EM005 adjuvanted vaccine induced a potent Th1 response cross-reactive to all the A/H3N2 strains evaluated. These results suggest that rational adjuvants can enhance both the magnitude and quality of protective humoral and cellular responses of influenza vaccines.

This work was supported in part by Grant #42387 from the Bill & Melinda Gates Foundation

Approaches to "Standardless" Wavelength Dispersive Analysis

In truly standardless electron microprobe analysis, generated X-ray intensities calculated from first principles are combined with a detector efficiency model. Though already used for energy dispersive (ED) analysis, the application of this concept to wavelength dispersive (WD) analysis is problematic, mainly because the reflectivity of spectrometer crystals is not well known. However, the need to carry out standard measurements with every batch of WD analyses can be avoided by using stored intensity data, and interpolation may be used when no standard is available. An empirical adjustment factor allowing for changes in spectrometer efficiency with time can be applied as necessitated by the variability of the spectrometer characteristics and the accuracy required. A similar approach to background corrections, based on measured continuum intensities, can be used. While the convenience of standardless WD analysis is attainable only at the expense of reduced accuracy, it can have a useful role where high accuracy is not needed or as a preliminary to applying a more rigorous routine using standards.

Design of a survey to inform state health decision making: a collaborative effort

BACKGROUND

The North Carolina Health Profile (NCHP), a statewide telephone survey, was introduced as part of the state's Health Policy Information Project aimed at enhancing the use of health data for state policy decision making and program management. A key factor in the creation of the NCHP was a collaboration between the State Center for Health Statistics and the Survey Research Unit at the University of North Carolina at Chapel Hill. The purpose of this article is to describe our partnership, the development of the survey design, and the dissemination of survey results.

METHODS

Three designs were considered during the planning and development of the survey. The final design consisted of a random digit dialing sample of 2,400 households in the state's noninstitutionalized population. The questionnaire was comprised of an adult module (addressing adult health care use and insurance coverage), a child module (addressing health care use and insurance coverage of children ages 0-17 years), and a young child module (addressing child development and safety for children ages 0-5 years).

RESULTS

Several statistical briefs, a report, a public dataset, and accompanying public use documentation were prepared for a variety of audiences, including state legislative committees and commissions, state agencies, and advocacy groups.

DISCUSSION

We learned several lessons in our research and practice partnership including the need for collaboration between data creators and users, for addressing obstacles in soliciting policy information needs, and for prioritization in meeting information needs.

Turbidimetric assay for virginiamycin in feeds and premixes

A turbidimetric assay method applicable to virginiamycin at level ranging from 5 g/ton in feeds to 50% in a premix is described. Incubation period is 4 h. Test organism is Streptococcus faecium ATCC 8043. On 6 levels of feed-grade material, the overall mean recovery was 6.75% Standard recovery studies resulted in RSD values ranging from 2.01 to 3.88% and a mean standard recovery of 100%.

Turbidimetric microbiological determination of oxytetracycline hydrochloride in finished feeds and a feed premix: collaborative study

New automated and manual turbidimetric microbiological assay methods for oxytetracycline (OTC) in finished feeds and a feed premix were submitted to 17 collaborating laboratories for comparison with the official AOAC method. Six finished feeds of 50 and 100 g/ton levels and one premix containing 20 g OTC/lb were sent to the collaborators. Results were received from 12 laboratories. Six laboratories provided results derived from the Autoturb System and 7 laboratories poerformed the turbidimetric analyses manually. All 12 laboratories assayed the samples by the AOAC cylinder-plate method. Ranges of recoveraies expressed as percent were 89.5-102.0, 91.2-97.0, and 91.4-96.0 for the AOAC, Autoturb turbidimetric, and manual turbidimetric methods, respectively. Average recoveries were 96.3, 93.4, and 93.6%, respectively. The mean relative standard deviation values were 5.7, 6.3, and 7.2, respectively. There was little significant difference between the turbidimetric methods and the AOAC method; however, the turbidimetric methods were faster.

Rapid automated turbidimetric assay for chlortetracycline hydrochloride, using Leuconostoc mesenteroides as the test organism

A rapid turbidimetric assay has been developed for chlortetracycline hydrochloride (CTC-HCl) in finished animal feeds and feed supplements, using Leuconostoc mesenteroides as the test organism. Two modifications are presented: The incubation period of modification 1 is 2.5 hr and the sensitivity of the assay is 0.03 microgram CTC-HCl/assay tube. Modification 2 has a sensitivty of 0.01 microgram CTC-HCl/assay tube and requires an incubation period of 3.5 hr. For 21 feed formulations, the turbidimetric method recovered 95.7% of label claim. Recoveries of CTC-HCl standards from the same feeds ranged from 93.4 to 134% with a mean of 103%. The relative standard deviation among day-to-day duplicates is 3.50% for the faster modification and 1.63% for the more sensitive modification.

Temperature-sensitive mutants of a Chinese hamster cell line. I. Selection of clones with defective macromolecular biosynthesis

Temperature-sensitive clones have been selected from a mutagenized culture of Chinese hamster lung cells by a procedure involving bromodeoxyuridine (BrdU) incorporation and irradiation with black light. The selection procedure used in these studies was adapted from methods developed by others to yield mutants that cease DNA replication within a short time after they are transferred to nonpermissive temperature. After mutagenesis with ethyl methanosulfonate ten clones survived the selection procedure. Three of the clones (mutants) were temperature-sensitive as measured by growth properties. Two mutants ceased DNA synthesis within six hours of being shifted to 39degrees and the third mutant continued to synthesize DNA at nonpermissive temperature at a reduced rate for at least 24 hours. Thus, all three mutants survived the selection procedure for understandable reasons, since each was unable to incorporate sufficient BrdU at 39degrees to lethally protosensitize its DNA during the standard exposure period. The two mutants that cease DNA synthesis at high temperature (clones 115-47 and 115-53) also stop incorporating radioactive amino acids and uridine within six hours at 39degrees. Their complex phenotype, i.e. defective DNA, RNA and protein biosynthesis, is reversible. When these mutants were returned to 33 degrees after 8 hours at 39 degrees, both resumed DNA synthesis immediately (less than 1 hour). Reversal of defective DNA synthesis in both mutants were sensitive to drugs that inhibit protein biosynthesis specifically. Those same drugs, as well as toxic amino acids analogs, also effected a striking mutant phenocopy in wild-type cells. The phenocopy produced by amino acid analogs that are incorporated into mammalian proteins suggested that one or more proteins must be synthesized continuously to support mammalian cells engaged in programmed DNA replication.