Development and biophysical characterization of a humanized FSH-blocking monoclonal antibody therapeutic formulated at an ultra-high concentration

Highly concentrated antibody formulations are oftentimes required for subcutaneous, self-administered biologics. Here, we report the development of a unique formulation for our first-in-class FSH-blocking humanized antibody, MS-Hu6, which we propose to move to the clinic for osteoporosis, obesity, and Alzheimer's disease. The studies were carried out using our Good Laboratory Practice (GLP) platform, compliant with the Code of Federal Regulations (Title 21, Part 58). We first used protein thermal shift, size exclusion chromatography, and dynamic light scattering to examine MS-Hu6 concentrations between 1 and 100 mg/mL. We found that thermal, monomeric, and colloidal stability of formulated MS-Hu6 was maintained at a concentration of 100 mg/mL. The addition of the antioxidant L-methionine and chelating agent disodium EDTA improved the formulation's long-term colloidal and thermal stability. Thermal stability was further confirmed by Nano differential scanning calorimetry (DSC). Physiochemical properties of formulated MS-Hu6, including viscosity, turbidity, and clarity, conformed with acceptable industry standards. That the structural integrity of MS-Hu6 in formulation was maintained was proven through Circular Dichroism (CD) and Fourier Transform Infrared (FTIR) spectroscopy. Three rapid freeze-thaw cycles at -80°C/25°C or -80°C/37°C further revealed excellent thermal and colloidal stability. Furthermore, formulated MS-Hu6, particularly its Fab domain, displayed thermal and monomeric storage stability for more than 90 days at 4°C and 25°C. Finally, the unfolding temperature (T_m) for formulated MS-Hu6 increased by >4.80°C upon binding to recombinant FSH, indicating highly specific ligand binding. Overall, we document the feasibility of developing a stable, manufacturable and transportable MS-Hu6 formulation at a ultra-high concentration at industry standards. The study should become a resource for developing biologic formulations in academic medical centers.

Development and Biophysical Characterization of a Humanized FSH-Blocking Monoclonal Antibody Therapeutic Formulated at an Ultra-High Concentration

Highly concentrated antibody formulations are oftentimes required for subcutaneous, self-administered biologics. Here, we report the creation of a unique formulation for our first-in- class FSH-blocking humanized antibody, MS-Hu6, which we propose to move to the clinic for osteoporosis, obesity, and Alzheimer's disease. The studies were carried out using our Good Laboratory Practice (GLP) platform, compliant with the Code of Federal Regulations (Title 21, Part 58). We first used protein thermal shift, size exclusion chromatography, and dynamic light scattering to examine MS-Hu6 concentrations between 1 and 100 mg/mL. We found that thermal, monomeric, and colloidal stability of formulated MS-Hu6 was maintained at a concentration of 100 mg/mL. The addition of the antioxidant L-methionine and chelating agent disodium EDTA improved the formulation's long-term colloidal and thermal stability. Thermal stability was further confirmed by Nano differential scanning calorimetry (DSC). Physiochemical properties of formulated MS-Hu6, including viscosity, turbidity, and clarity, conformed with acceptable industry standards. That the structural integrity of MS-Hu6 in formulation was maintained was proven through Circular Dichroism (CD) and Fourier Transform Infrared (FTIR) spectroscopy. Three rapid freeze-thaw cycles at -80°C/25°C or -80°C/37°C further revealed excellent thermal and colloidal stability. Furthermore, formulated MS-Hu6, particularly its Fab domain, displayed thermal and monomeric storage stability for more than 90 days at 4°C and 25°C. Finally, the unfolding temperature (T _m ) for formulated MS-Hu6 increased by >4.80°C upon binding to recombinant FSH, indicating highly specific ligand binding. Overall, we document the feasibility of developing a stable, manufacturable and transportable MS-Hu6 formulation at a ultra-high concentration at industry standards. The study should become a resource for developing biologic formulations in academic medical centers.

Optimizing a therapeutic humanized follicle-stimulating hormone-blocking antibody formulation by protein thermal shift assay

Biopharmaceutical products are formulated using several Food and Drug Administration (FDA) approved excipients within the inactive ingredient limit to maintain their storage stability and shelf life. Here, we have screened and optimized different sets of excipient combinations to yield a thermally stable formulation for the humanized follicle-stimulating hormone (FSH)-blocking antibody, MS-Hu6. We used a protein thermal shift assay in which rising temperatures resulted in the maximal unfolding of the protein at the melting temperature (T_m ). To determine the buffer and pH for a stable solution, four different buffers with a pH range from 3 to 8 were screened. This resulted in maximal T_m s at pH 5.62 for Fab in phosphate buffer and at pH 6.85 for Fc in histidine buffer. Upon testing a range of salt concentrations, MS-Hu6 was found to be more stable at lower concentrations, likely due to reduced hydrophobic effects. Molecular dynamics simulations revealed a higher root-mean-square deviation with 1 mM than with 100 mM salt, indicating enhanced stability, as noted experimentally. Among the stabilizers tested, Tween 20 was found to yield the highest T_m and reversed the salt effect. Among several polyols/sugars, trehalose and sucrose were found to produce higher thermal stabilities. Finally, binding of recombinant human FSH to MS-Hu6 in a final formulation (20 mM phosphate buffer, 1 mM NaCl, 0.001% w/v Tween 20, and 260 mM trehalose) resulted in a thermal shift (increase in T_m ) for the Fab, but expectedly not in the Fc domain. Given that we used a low dose of MS-Hu6 (1 μM), the next challenge would be to determine whether 100-fold higher, industry-standard concentrations are equally stable.

PMON51 A Single Multipurpose FSH–Blocking Therapeutic for Osteoporosis, Obesity and Alzheimer's Disease

Pharmacological and genetic studies over the past decade suggest that FSH is an actionable target for diseases affecting millions, notably osteoporosis, obesity and Alzheimer's disease (AD). Blocking FSH action prevents bone loss (1, 2), fat and energy metabolism (3) and AD–like features in mice (4). We recently developed a first–in–class, humanized, epitope–specific FSH blocking antibody that binds to a 13–amino–acid–long sequence of FSHβ—"MS-Hu6"—with a KD of 7.52 nM (5). We showed that MS-Hu6 bound specifically to FSHβ and its different glycosylated forms, namely FSHβ21/18 and FSHβ²⁴, without binding to LH and TSH. Here, using a GLP–compliant platform, we report the efficacy of MS-Hu6 in preventing obesity, osteoporosis and AD in mice. Notably, MS-Hu6-treated mice showed lower body weight and fat mass, increased lean mass (qNMR) and evidence of beiging in ThermoMice (IVIS imaging) compared with IgG–treated mice. Consistent with this, the thermogenic genes Ucp1 and Cidea were upregulated, whereas Pparg expression was attenuated in fat depots. Treatment of ThermoMice for 8 weeks also increased bone mineral density (BMD), improved microstructure (micro-CT), elevated bone formation (dynamic histomorphometry), and upregulated the osteoblastic genes Alp and Col1a1. The increase in bone mass and improved microstructure were replicated in C.J.R's lab using female mice 24 weeks post–ovariectomy. Preliminary testing using AD mice, namely APP/PS1 mice, showed that MS-Hu6 prevented the impairment in recognition and contextual memory. Biodistribution studies using 89Zr–labelled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone, bone marrow and fat depots. MS-Hu6 displayed a β phase t½ of 13 days (316 hours) in humanized Tg32 mice, and bound endogenous FSH. In monkeys, an acute single injection of MS-Hu6 did not affect vitals, and biochemical parameters remained within the normative range. We tested 215 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze–thaw and at different temperatures, with minimal aggregation, and without self–, cross–, or hydrophobic interactions or appreciable binding to relevant human antigens. MS-Hu6 showed the same level of "humanness" as human IgG1 in silico, and was non–immunogenic in ELISPOT assays for IL-2 and IFNγ in human peripheral blood mononuclear cell cultures. In conclusion, MS-Hu6 is efficacious, durable and manufacturable, and is therefore poised for future human testing as a multipurpose therapeutic for obesity, osteoporosis, and perhaps for AD.References: ¹Sun et al., Cell, 2006, PMID: 16630814; Ji et al, PNAS, 2018, PMID: 29440419; ³Liu et al., Nature, 2017, PMID: 28538730; ⁴Xiong et al., Nature (In press); ⁵Gera et al., PNAS, 2020, PMID: 33127753

Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

FSH-blocking therapeutic for osteoporosis

Pharmacological and genetic studies over the past decade have established the follicle-stimulating hormone (FSH) as an actionable target for diseases affecting millions, namely osteoporosis, obesity, and Alzheimer's disease. Blocking FSH action prevents bone loss, fat gain and neurodegeneration in mice. We recently developed a first-in-class, humanized, epitope-specific FSH-blocking antibody, MS-Hu6, with a K_D of 7.52 nM. Using a GLP-compliant platform, we now report the efficacy of MS-Hu6 in preventing and treating osteoporosis in mice and parameters of acute safety in monkeys. Biodistribution studies using ⁸⁹Zr-labelled, biotinylated or unconjugated MS-Hu6 in mice and monkeys showed localization to bone and bone marrow. MS-Hu6 displayed a β phase t_½ of 7.5 days (180 hours) in humanized Tg32 mice. We tested 217 variations of excipients using the protein thermal shift assay to generate a final formulation that rendered MS-Hu6 stable in solution upon freeze-thaw and at different temperatures, with minimal aggregation, and without self-, cross-, or hydrophobic interactions or appreciable binding to relevant human antigens. MS-Hu6 showed the same level of 'humanness' as human IgG1 in silico and was non-immunogenic in ELISPOT assays for IL-2 and IFNg in human peripheral blood mononuclear cell cultures. We conclude that MS-Hu6 is efficacious, durable, and manufacturable, and is therefore poised for future human testing.

Abstract CT108: Immunogenicity of Poly-ICLC matured dendritic cells as an adjuvant for NY-ESO-1 and Melan-A-MART-1 peptide vaccination compared to Montanide® ISA-51 VG, in study subjects with melanoma in complete clinical remission but at high risk of disease recurrence

Background: Dendritic cells (DCs) play a critical role in anti-tumor immune response. However, tumor-induced immunosuppression promotes DC dysfunction and T cell exhaustion resulting in evasion of tumor immunity. In this study, we aimed to compare two approaches for engaging DCs and inducing an immune response to tumor antigens in the absence of tumor (melanoma)

Methods: This is a Phase II open-label, randomized, two-arm study to compare Arm A: Poly-ICLC-matured DC+PolyICLC to Arm B: Montanide ISA-51-VG+Poly-ICLC, as adjuvants for NY-ESO-1 and Melan-A/MART-1 long peptides in patients with melanoma in complete clinical remission but at high risk of disease recurrence (NCT02334735). Each arm also received helper peptide, keyhole limpet hemocyanin (KLH) with the first vaccine and Poly-ICLC on day 2 of each vaccine. 36 patients were consented and randomized. Of these, 31 subjects received treatment, 16 in Arm A and 15 in Arm B. Immunohistochemistry (IHC) was used to determine expression of NY-ESO-1 and Melan-A/MART-1 and to determine the immune infiltrate landscape in the primary tumors. Humoral responses, TCR clonality, and inflammatory pathways were assessed by ELISA, bulk TCR sequencing, and Olink, respectively. Functional T-cell responses were investigated ex-vivo by interferon (IFN)-g enzyme-linked immunospot assay (ELISPOT) and after expansion by intracellular cytokine staining.

Results: Arm B induced a stronger humoral response vs Arm A against both Melan-A/MART-1 and NY-ESO-1. A stronger ex vivo IFN-g response as well as expanded CD4+ T cell response against NY-ESO-1 was also induced in Arm B. However, the response to Melan-A/MART-1, as measured by ex vivo ELISPOT and expanded CD4+T cell assay, was comparable in both arms. Interestingly, while similar proportions of patients in each arm displayed a CD8+ T cell response to NYESO-1, more patients in Arm A vs Arm B responded with a CD8+ T cell response to Melan-A/MART-1 (9/16 responders in Arm A vs 4/14 in Arm B). Melan-A expression was observed in 81% of the patients but did not correlate with antigen specific immune response. TCR sequencing, Olink analysis and evaluation of NY-ESO-1 expression and immune infiltrates in the primary tumors is ongoing.

Conclusion: This trial reached the primary endpoint of safety and tolerability. Arm B induced a stronger antibody and CD4+ T cell response, especially to NY-ESO-1, whereas the Arm A vaccine appears to be more efficient at eliciting CD8+ T cell responses against MelanA/MART1. The seemingly enhanced CD8 T cell response in Arm A versus Arm B, could be attributed to frequency of specific HLA-I alleles in either arm or pre-existing immune response in select patients. A deeper investigation into correlation between HLA type and cellular immune response to vaccine is ongoing.

Citation Format: Mansi Saxena, Ashleih Burke, Anna Pavlick, Ana Blazquez, Gustavo Gimenez, Marcia Meseck, Michael Donovan, Denise Rodriguez, Mireia Castillo-Martin, Tin Htwe Thin, Rachel Sabado, John Mandeli, Sacha Gnjatic, Philip Friedlander, Nina Bhardwaj. Immunogenicity of Poly-ICLC matured dendritic cells as an adjuvant for NY-ESO-1 and Melan-A-MART-1 peptide vaccination compared to Montanide® ISA-51 VG, in study subjects with melanoma in complete clinical remission but at high risk of disease recurrence [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 CT108.

Safety and immunogenicity of an inactivated recombinant Newcastle disease virus vaccine expressing SARS-CoV-2 spike: Interim results of a randomised, placebo-controlled, phase 1 trial

BACKGROUND

Production of affordable coronavirus disease 2019 (COVID-19) vaccines in low- and middle-income countries is needed. NDV-HXP-S is an inactivated egg-based recombinant Newcastle disease virus vaccine expressing the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It's being developed by public sector manufacturers in Thailand, Vietnam, and Brazil; herein are initial results from Thailand.

METHODS

This phase 1 stage of a randomised, dose-escalation, observer-blind, placebo-controlled, phase 1/2 trial was conducted at the Vaccine Trial Centre, Mahidol University (Bangkok). Healthy males and non-pregnant females, aged 18-59 years and negative for SARS-CoV-2 antibodies, were eligible. Participants were randomised to receive one of six treatments by intramuscular injection twice, 28 days apart: 1 µg, 1 µg+CpG1018 (a toll-like receptor 9 agonist), 3 µg, 3 µg+CpG1018, 10 µg, or placebo. Participants and personnel assessing outcomes were masked to treatment. The primary outcomes were solicited and spontaneously reported adverse events (AEs) during 7 and 28 days after each vaccination, respectively. Secondary outcomes were immunogenicity measures (anti-S IgG and pseudotyped virus neutralisation). An interim analysis assessed safety at day 57 in treatment-exposed individuals and immunogenicity through day 43 per protocol. ClinicalTrials.gov (NCT04764422).

FINDINGS

Between March 20 and April 23, 2021, 377 individuals were screened and 210 were enroled (35 per group); all received dose one; five missed dose two. The most common solicited AEs among vaccinees, all predominantly mild, were injection site pain (<63%), fatigue (<35%), headache (<32%), and myalgia (<32%). The proportion reporting a vaccine-related AE ranged from 5·7% to 17·1% among vaccine groups and was 2·9% in controls; there was no vaccine-related serious adverse event. The 10 µg formulation's immunogenicity ranked best, followed by 3 µg+CpG1018, 3 µg, 1 µg+CpG1018, and 1 µg formulations. On day 43, the geometric mean concentrations of 50% neutralising antibody ranged from 122·23 international units per mL (IU/mL; 1 µg, 95% confidence interval (CI) 86·40-172·91) to 474·35 IU/mL (10 µg, 95% CI 320·90-701·19), with 93·9% to 100% of vaccine groups attaining a ≥ 4-fold increase over baseline.

INTERPRETATION

NDV-HXP-S had an acceptable safety profile and potent immunogenicity. The 3 µg and 3 µg+CpG1018 formulations advanced to phase 2.

FUNDING

National Vaccine Institute (Thailand), National Research Council (Thailand), Bill & Melinda Gates Foundation, National Institutes of Health (USA).

Safety and Immunogenicity of an Inactivated Recombinant Newcastle Disease Virus Vaccine Expressing SARS-CoV-2 Spike: Interim Results of a Randomised, Placebo-Controlled, Phase 1/2 Trial

Background

Production of affordable coronavirus disease 2019 (COVID-19) vaccines in low- and middle-income countries is needed. NDV-HXP-S is an inactivated egg-based Newcastle disease virus vaccine expressing the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It's being developed in Thailand, Vietnam, and Brazil; herein are initial results from Thailand.

Methods

This phase 1 stage of a randomised, dose-escalation, observer-blind, placebo-controlled, phase 1/2 trial was conducted at the Vaccine Trial Centre, Mahidol University (Bangkok). Healthy adults aged 18-59 years, non-pregnant and negative for SARS-CoV-2 antibodies were eligible. Participants were block randomised to receive one of six treatments by intramuscular injection twice, 28 days apart: 1 µg±CpG1018 (a toll-like receptor 9 agonist), 3 µg±CpG1018, 10 µg, or placebo. Participants and personnel assessing outcomes were masked to treatment. The primary outcomes were solicited and spontaneously reported adverse events (AEs) during 7 and 28 days after each vaccination, respectively. Secondary outcomes were immunogenicity measures (anti-S IgG and pseudotyped virus neutralisation). An interim analysis assessed safety at day 57 in treatment-exposed individuals and immunogenicity through day 43 per protocol. ClinicalTrials.gov ( NCT04764422 ).

Findings

Between March 20 and April 23, 2021, 377 individuals were screened and 210 were enrolled (35 per group); all received dose one; five missed dose two. The most common solicited AEs among vaccinees, all predominantly mild, were injection site pain (<63%), fatigue (<35%), headache (<32%), and myalgia (<32%). The proportion reporting a vaccine-related AE ranged from 5·7% to 17·1% among vaccine groups and was 2·9% in controls; there was no vaccine-related serious adverse event. The 10 µg formulation's immunogenicity ranked best, followed by 3 µg+CpG1018, 3 µg, 1 µg+CpG1018, and 1 µg formulations. On day 43, the geometric mean concentrations of 50% neutralising antibody ranged from 122·23 IU/mL (1 µg, 95% CI 86·40-172·91) to 474·35 IU/mL (10 µg, 95% CI 320·90-701·19), with 93·9% to 100% of vaccine groups attaining a ≥4-fold increase over baseline.

Interpretation

NDV-HXP-S had an acceptable safety profile and potent immunogenicity. The 3 µg and 3 µg+CpG1018 formulations advanced to phase 2.

Funding

National Vaccine Institute (Thailand), National Research Council (Thailand), Bill & Melinda Gates Foundation, National Institutes of Health (USA).

Abstract LB048: An adjuvant personalized neoantigen peptide vaccine for the treatment of malignancies (PGV-001)

Background: The majority of novel cancer immunotherapies rely on adequate priming of T cells to tumor-specific neoantigens, which is believed to be lacking in patients who do not respond to therapy. We developed a personalized genomic vaccine (PGV-001) in which patient-specific synthetic neoantigen peptides (25 mer),are formulated and administered to patients with multiple cancer types in the adjuvant setting (NCT02721043). Methods: This trial enrolled patients whom had undergone curative-intent surgery (solid tumor patients) or autologous stem cell transplant (multiple myeloma patients), and for whom there was &gt;30% chance of recurrence. Sequencing of tumor and germline DNA and RNA was performed and the OpenVax custom computation pipeline was used to identify candidate neoantigens; this platform ranks transcribed mutations using predicted MHC-I binding affinity and neoantigen abundance. A maximum of 10 peptides were synthesized per patient. Peptides were administered over the course of 27 weeks with poly-ICLC and a tetanus helper peptide. Primary objectives were to determine the safety and tolerability of vaccination, feasibility of vaccine production and administration, and immunogenicity. Results: Within 15 patients enrolled, the OpenVax pipeline identified an average of 67.1 neoantigens/patient (range 8-193), only two patients did not have adequate number of neoantigens identified to synthesize 10 peptides. 13 of the 15 patients received PGV-001, including 10 patients with solid tumor diagnoses and 3 patients with multiple myeloma, 11 of whom received all 10 doses, while 1 experienced progression of disease while on treatment. The vaccine was well tolerated, with grade 1 injection site reactions in 31% of patients, and grade 1 fever in one patient; there were no other significant adverse events. While one patient was lost to follow-up, of the remaining 12 patients the median progression-free survival from the time of their surgery or transplant of 618 days. With a mean follow-up of 925 days, 4 patients remain without evidence of disease, 4 patients are receiving subsequent lines of therapy, and 4 patients have died, though notably only two with documented recurrence of their malignancy. Initial analysis of the patient samples analyzed confirms immunogenicity. T cell responses were measured using ex vivo ELISpot and intracellular cytokine staining following expansion with neoantigen peptide libraries, both demonstrating induction of IFN-gamma, TNF-alpha and IL-2. Notably, robust T cell reactivity was only seen at the completion of all 10 vaccines, supporting the need for a prolonged schedule. Conclusions: PGV-001 was successfully synthesized for 15 patients and administered successfully to 13 patients without significant adverse events. Immune monitoring of immunogenicity is ongoing, with initial analysis demonstrating induction of neoantigen-specific CD4 and CD8 T cell expansion.

Citation Format: Thomas Urban Marron, Mansi Saxena, Nina Bhardwaj, Marcia Meseck, Alex Rubinsteyn, John Finnigan, Julia Kodysh, Ana Blazquez, Tim O'Donnel, Mathew Galsky, Deborah Doroshow, Brett Miles, Krysztof Misiukiewicz, Hanna Irie, Amy Tiersten, Samir Parekh, Marshall Posner, Andrea Wolf, John Mandeli, Rachel Brody, Sacha Gnjatic, Eric Schadt, Philip Friedlander, Jeffrey Hammerbacher. An adjuvant personalized neoantigen peptide vaccine for the treatment of malignancies (PGV-001) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB048.

Abstract CT173: PGV-001: A phase I trial of a multipeptide personalized neoantigen vaccine in the adjuvant setting

Background: Mutation-derived tumor antigens (MTAs) arise as a result of somatic mutations, such as nucleotide substitutions and small insertions/deletions. MTAs can serve as specific targets for antitumor therapy, including neoantigen vaccines. The goal of neoantigen vaccination is to help prime T cells to recognize such tumor-specific mutations. Here we describe a phase I trial testing a personalized genomic vaccine (PGV-001) in multiple histologies in the adjuvant setting (NCT02721043).

Methods: This trial included patients with histologic diagnosis of solid malignancies or multiple myeloma with a &gt;30% risk of recurrence but no measurable disease at the time of first vaccination. For each patient, HLA typing was performed, and the patient's tumor and germline DNA and tumor RNA were sequenced. Mutated peptides containing predicted neoantigens were selected using the OpenVax computational pipeline, which prioritizes somatic mutations by expression of the mutant allele in the tumor RNA and predicted MHC class I epitope binding for the patient's HLA type. A maximum of 10 peptides was included in each patient's personalized vaccine. The vaccine was administered over the course of 6 months, given in combination with poly-ICLC as the adjuvant. The primary objectives were to determine safety and tolerability, feasibility, and immunogenicity of the PGV-001 neoantigen vaccine.

Results: The neoantigen vaccine was successfully administered to 13 patients, spanning 5 different tumor types. For each patient, an average of 1730 somatic mutations were identified (range 521-5106), of which 349 were coding variants (range 68-1493), 88 were coding and expressed in the tumor RNA (range 9-233), and 71 were coding, expressed and resulted in predicted MHC class I ligands (range 8-193). The urothelial, head & neck, and lung tumors resulted in larger numbers of predicted neoantigens than in the cases of multiple myeloma or breast tumors. Despite this difference, each of the 13 patient tumor samples showed enough of a neoantigen load to enable vaccination. We have also initiated analysis of immunogenicity, and early reports demonstrate neoantigen-specific CD4 and CD8 T-cell responses.

Conclusions: The PGV-001 personalized neoantigen vaccine was successfully administered to 13 patients, where each patient's neoantigen load was adequate for vaccine synthesis. While we have demonstrated the computational feasibility of identification of neoantigens for inclusion in the PGV-001 genomic vaccine, clinical outcomes will be reported separately.

Citation Format: Julia Kodysh, Thomas Marron, Alex Rubinsteyn, Tim O'Donnell, John Finnigan, Ana Blazquez, Mansi Saxena, Marcia Meseck, Philip Friedlander, Nina Bhardwaj. PGV-001: A phase I trial of a multipeptide personalized neoantigen vaccine in the adjuvant setting [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT173.

Combined Vaccination with NY-ESO-1 Protein, Poly-ICLC, and Montanide Improves Humoral and Cellular Immune Responses in Patients with High-Risk Melanoma

Given its ability to induce both humoral and cellular immune responses, NY-ESO-1 has been considered a suitable antigen for a cancer vaccine. Despite promising results from early-phase clinical studies in patients with melanoma, NY-ESO-1 vaccine immunotherapy has not been widely investigated in larger trials; consequently, many questions remain as to the optimal vaccine formulation, predictive biomarkers, and sequencing and timing of vaccines in melanoma treatment. We conducted an adjuvant phase I/II clinical trial in high-risk resected melanoma to optimize the delivery of poly-ICLC, a TLR-3/MDA-5 agonist, as a component of vaccine formulation. A phase I dose-escalation part was undertaken to identify the MTD of poly-ICLC administered in combination with NY-ESO-1 and montanide. This was followed by a randomized phase II part investigating the MTD of poly-ICLC with NY-ESO-1 with or without montanide. The vaccine regimens were generally well tolerated, with no treatment-related grade 3/4 adverse events. Both regimens induced integrated NY-ESO-1-specific CD4+ T-cell and humoral responses. CD8+ T-cell responses were mainly detected in patients receiving montanide. T-cell avidity toward NY-ESO-1 peptides was higher in patients vaccinated with montanide. In conclusion, NY-ESO-1 protein in combination with poly-ICLC is safe, well tolerated, and capable of inducing integrated antibody and CD4+ T-cell responses in most patients. Combination with montanide enhances antigen-specific T-cell avidity and CD8+ T-cell cross-priming in a fraction of patients, indicating that montanide contributes to the induction of specific CD8+ T-cell responses to NY-ESO-1.

Abstract CT096: Phase I study of in situ autologous vaccination for prostate cancer in a neo-adjuvant setting

Background:

Certain solid malignancies like prostate cancer pose two major challenges for effective immunotherapy. The inherently low mutation load and spatial and temporal intra-tumor heterogeneity yields an immune exclusion and development of an “immune desert” within the tumor micro-environment (TME). Additionally, there is a response failure to immunomodulation, due to tumor/patient immunosuppressive mechanisms. In an effort to transform the prostate tumor environment into an immunogenic ecosystem, we are using PolyIC:LC as an immunemodulator. The novelty of this approach is a “host targeted”, in-situ “autovaccination” strategy, which uses the patient’s own tumor as the antigen source leading to activation of both an innate and adaptive immune response. As all patients will have their cancer removed after investigational therapy we can study baseline versus treatment induced changes in bio-specimens collected before, during, and after patients are exposed to PolyIC:LC. Correlative studies include characterization of tissue and systemic biomarkers of response using multiple platforms like cytometry by time of flight (CyTOF), RNA-seq, whole exome sequencing, seromics, TCR-sequencing, neoantigen specific T-cell responses, as well as assessing circulating tumor DNA (ctDNA) at multiple time points to determine the potential in detecting tumor response to immunemodulation.

Methods:

This is a Phase I dose escalation study (NCT03262103) seeking to determine a safe dose and schedule of intratumoral (IT) plus intramuscular (IM) PolyIC:LC injections prior to radical prostatectomy in patients with prostate cancer. The dose and frequency of IT PolyIC:LC will be increased in successive cohorts using a 3+3 design and traditional dose escalation rules. The dose and schedule of IM PolyIC:LC will remain fixed in successive cohorts. The study will consist of 24 enrolled subjects, recruited into cohorts consisting of a minimum of 3 and maximum of 6 patients per cohort. The first cohort, consisting of three patients, has been completed. Recruitment for the second cohort has begun with two patients already enrolled. The inclusion criteria extend to patients diagnosed with high risk (Gleason 7-10, cT2a-cT3b) clinically localized prostate cancer with no prior hormonal or radiation therapy and with plans to undergo radical prostatectomy. Week 1 serves as the priming course with the patient coming in for a pre-treatment biopsy followed by an IT injection. Weeks 3-6 consist of a booster treatment course with IM injections two times a week. Weeks 7-9 are a rest period with no injections followed by radical prostatectomy at week 10. Blood is drawn at weeks 1, 3, 6, and 9. At the time of surgery, blood, tissue, and lymph node are collected for research purposes. Following each IT and IM injection, the subject remains in clinic for monitoring for at least 1 hour or 30 minutes respectively. Patients are seen 6 weeks post-prostatectomy as per standard of care. The next follow-up visit is approximately 3 months following surgery where the first post-operative PSA check is performed. Assuming PSA levels are undetectable, the patient is followed up at routine intervals for PSA testing.

Citation Format: Sujit S. Nair, Rachel Weil, Elena Gonzalez-Gugel, Marcia Meseck, Alex Rubinsteyn, Yulia Kodysh, Akriti Gupta, Keerthi Sadanala, Kacie Schlussel, Kamala Bhatt, Avinash Reddy, Rajan Patel, Tin Thawte, Adam Farkas, Siarhei Dzedzik, Kenneth Haines, Julia Wagner, Macy Robison, Cynthia Knauer, Andres Salazar, Matthew Galsky, Nina Bhardwaj, Ashutosh Tewari. Phase I study of in situ autologous vaccination for prostate cancer in a neo-adjuvant setting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT096.

A phase I study of the safety and immunogenicity of a multi-peptide personalized genomic vaccine in the adjuvant treatment of solid tumors and hematological malignancies

e14307

Background: Mutation-derived tumor antigens (MTAs) arise as a direct result of somatic variations that occur during carcinogenesis and can be characterized via genetic sequencing and used to identify MTAs. We developed a platform for a fully-personalized MTA-based vaccine in the adjuvant treatment of solid and hematological malignancies. Methods: This is a single-arm, open label, proof-of-concept phase I study designed to test the safety and immunogenicity of Personalized Genomic Vaccine 001 (PGV001) that targets up to 10 predicted personal tumor neoantigens based on patient’s HLA profile (ClinicalTrials.gov: NCT02721043). Results: Patients who completed vaccination with PGV001_002 (head and neck squamous cell cancer) received 10 doses of vaccine comprising 10 long peptides (LP) combined with poly-ICLC (toll-like receptor-3 agonist) intradermally. Vaccine-induced T-cell responses were determined at weeks 0 and 27 (before and after treatment, respectively), ex vivo by interferon (IFN)-g enzyme-linked immunospot assay and after expansion by intracellular cytokine staining. Overlapping 15-mer peptides (OLPs) spanning the entirety of each LP and 9-10-mer peptides corresponding to each predicted class I epitope (Min) were pooled. Ex vivo responses to these peptide pools were undetectable at week 0 but were evident at week 27 against 2 OLPs out of 10 (20%) and in 5 Min out of 10 (50%). After in vitro expansion, neoantigen-specific CD4+ and CD8+ T-cell responses were found in 5 out of 10 pooled peptides (50%). 7 out of 10 (70%) epitopes elicited polyfunctional T-cell responses (secretion of INF-g, TNF-a, and/or IL-2) from either CD4+ or CD8+ T cells. Conclusions: The PGV001 vaccine in our first patient showed both safety and immunogenicity, eliciting CD4+ and CD8+ responses to the vaccine peptides. As we enroll additional patients in this clinical trial, and perform deeper phenotyping of their tumor-reactive T cells, we will learn the determinants necessary for the successful generation of MTA-based vaccines, while informing future immunotherapeutic approaches and rational combinations. Clinical trial information: NCT02721043.

A phase II open labeled, randomized study of poly-ICLC matured dendritic cells for NY-ESO-1 and Mean-A peptide vaccination compared to Montanide, in melanoma patients in complete clinical remission

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Background: Dendritic cells (DC) play a critical role in tumor immune-surveillance. Combination therapies by utilizing check point inhibitors may revert tumor-induced-T cell exhaustion; however, DCs are necessary to prime/activate T cells to target tumor cells. Montanide is a mineral oil-based adjuvant that enhances the immune response to vaccination. In this study, we compared the immunogenicity of Montanide and poly-ICLC-matured DCs. Methods: This is a Phase II open label, randomized two arm study to compare Poly-ICLC matured DC with systemic administration of Poly-ICLC on days 1 and 2 (ARM A) to Montanide ISA-51 and Poly-ICLC as adjuvants for NY-ESO-1 and Melan-A/MART-1 peptide vaccination with systemic administration of Poly-ICLC on day 2 (ARM B) in study subjects with melanoma in complete clinical remission but at high risk of disease recurrence (NCT02334735). Evaluation of primary tumor expression of NY-ESO-1 and Melan-A tumor was determined by immunohistochemistry (IHC). Humoral responses were assessed by Seromics (ELISA) and T-cell responses were performed ex-vivo by interferon (IFN)-g enzyme-linked immunospot assay (ELISPOT) and after expansion by intracellular cytokine staining (ICS). Results: Twenty-nine patients have been enrolled in this study. IHC studies demonstrated tumor expression of NY-ESO-1 and Melan-A in 78% and 81% of the patients, respectively. 100% of patients within arm B became seropositive for NY-ESO-1 peptide by cycle 2 day 8 (C2D8). 80% of patients within arm A also seroconverted to this antigen but titers were significantly lower. Melan-A-specific antibody responses were also found in arm B patients, but to a lesser degree. However, arm A patients failed to develop seroreactivity to Melan-A. Cellular responses are under analysis. Preliminary data show that subjects in both arms develop T cell responses to both antigens. Conclusions: This vaccine trial reached the primary endpoint of safety and tolerability. Patients vaccinated with either DC or Montanide had demonstrable antibody titers to immunizing antigens, although the latter reproducibly induced higher titers. Evaluation of cellular responses is ongoing. Clinical trial information: NCT02334735.

Abstract B032: PhIP-seq assessment of the serum antibody repertoire before and after immune-related adverse events in four melanoma patients treated with checkpoint blockade immunotherapy

Phage immunoprecipitation sequencing (PhIP-seq) is a technique to profile the epitope specificities of an antibody repertoire by phage display of a peptide library followed by immunoprecipitation and next-generation sequencing (1). We have developed phage libraries corresponding to all 36-mer peptides in the human proteome (approximately 413,000 peptides), as well as libraries of peptides found in viruses, bacteria, and toxins. Here, in a pilot study to understand if PhIP-seq might be used to identify predictive biomarkers for immune-related adverse events (irAE) in the context of checkpoint blockade immunotherapy, we applied the human proteome library to probe the self-directed IgG response in sera from four melanoma patients receiving checkpoint blockade who experienced irAE. In total, 16 serum samples acquired at the pre-treatment, post-treatment / pre-irAE, or post-irAE timepoints were assayed from these patients. We additionally analyzed samples from six melanoma patients who received vaccines targeting the MART-1 and NY-ESO-1 antigens. Using a stringent confidence threshold, we identified a median 31 self-directed antibody specificities (hits) at the pre-immunotherapy timepoint in these cancer patients and 41.5 hits post-therapy, compared to a median 6.5 hits in healthy donors. Patients receiving combination checkpoint blockade showed more hits than those treated with monotherapy. For a patient who received combination nivolumab and ipilimumab and developed a hepatic irAE, a cluster of 25 hits (of 161 total) was detected uniquely in a sample taken within two months subsequent to the adverse event. This cluster included a peptide from the C-Reactive Protein (CRP) gene and other genes expressed in the liver (EHBP1, VSTM2L), or across tissues (SAFB2), but also included genes with low expression in the liver (SPTBN4, DMBT1, IQGAP3, SPTBN4). In a patient who received ipilimumab and nivolumab and developed myalgia, hits against targets associated with autoimmune disease were found including NUMA1 (connective tissue autoimmunity), TRPM1 (melanoma-associated retinopathy), as well as three epitopes in the Mediator Of DNA Damage Checkpoint 1 (MDC1) gene. Finally, for three patients receiving a peptide vaccine targeting MART-1 and NY-ESO-1 with adjuvant poly-ICLC and montanide, we detected an IgG response against NY-ESO-1, but not MART-1, in each patient. No response to either protein was observed in three patients receiving a dendritic cell vaccine against the same antigens.Our small study suggests that PhIP-seq readily detects changes in the epitope specificities of the serum antibody repertoire in the course of immunotherapy. A key limitation of PhIP-seq is that the method can only detect antibodies with specificities for linear (as opposed to conformational) epitopes. Nevertheless, the assay’s low cost (approximately $30 per sample), small sample size requirement (1 µL serum), and ability to work with dried blood spot samples may make it an attractive technology to discover serological predictors of irAE in larger cohorts. References: 1. Larman HB, Zhao Z, Laserson U, Li MZ, Ciccia A, Gakidis MA, Church GM, Kesari S, Leproust EM, Solimini NL, Elledge SJ. Autoantigen discovery with a synthetic human peptidome. Nat Biotechnol 2011;29(6):535–41.

Citation Format: Timothy J. O’Donnell, Meimi Shan, Elliott Merritt, Elena Gonzalez Gugel, Ana B. Blasquez, Marcia Meseck, Phillip A. Friedlander, Alexander Rubinsteyn, Amir Horowitz, Nina Bhardwaj, Uri Laserson. PhIP-seq assessment of the serum antibody repertoire before and after immune-related adverse events in four melanoma patients treated with checkpoint blockade immunotherapy [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B032.

Abstract A005: A phase I study of the safety and immunogenicity of a multipeptide personalized genomic vaccine in the adjuvant treatment of solid cancers

Introduction: Mutation-derived tumor antigens (MTAs) arise as a direct result of somatic variations, including nucleotide substitutions, insertions, and deletions that occur during carcinogenesis. These somatic variations can be characterized via genetic sequencing and used to identify MTAs. We developed a platform for a fully-personalized MTA-based vaccine in the adjuvant treatment of solid and hematologic malignanicies. Methods: This is a single-arm, open label, proof-of-concept phase I study designed to test the safety and immunogenicity of Personalized Genomic Vaccine 001 (PGV001) that targets up to 10 predicted personal tumor neoantigens. The single-center study will enroll 20 eligible subjects with histologic diagnosis of solid and hematologic malignancies. Subjects must have no measurable disease at time of first vaccine administration, and 5-year disease recurrence risk of &gt; 30%. Toxicity will be defined by CTCAE v5.0. Blood samples will be collected at various time points for immune response monitoring. Each patient’s vaccine peptides are selected by identifying somatic mutations from comparison of tumor and normal exome sequencing data, phasing somatic variants with co-occurring germline variants using tumor RNA sequencing data, and ranking mutated peptide sequences ”Openvax pipeline.” The process for determining somatic variants hews closely to the Broad Institute’s “Best Practices” for cancer SNVs and indels. The phasing of somatic and germline variants is implemented in a custom bioinformatics tool called Isovar. Mutated protein sequences containing phased variants are ranked according to two criteria: expression of the mutant allele in tumor RNA and aggregated predicted affinity to the patient’s Class I MHCs. Both quantities are normalized and multiplied together to create single ranked ordering of the candidate mutant sequences. Results: PGV001_002 (head and neck squamous cell cancer), who has completed vaccination, received 10 doses of vaccine comprising 10 long peptides (25 amino acid length) combined with poly-ICLC (toll-like receptor-3 agonist) intradermally. Vaccine-induced blood T-cell responses were determined, at weeks 0 (before-treatment) and 27 (after-treatment), ex vivo by interferon (IFN)-g enzyme-linked immunospot (ELISPOT) assay and after in vitro expansion by intracellular cytokine staining (ICS). Overlapping 15-16-mer assays peptides (OLPs) spanning the entirety of each ILP and 9-10-mer peptides corresponding to each predicted class I epitope (Min) were pooled and used to monitor immunogenicity. Ex vivo responses to these peptide pools were undetectable at week 0 but were evident at week 27 against 2 OLPs out of 10 (20%) and in 5 Min out of 10 (50%). After in vitro expansion, neoantigen-specific CD4+ and CD8+ T-cell responses were found in 5 out of 10 pooled peptides (50%). 7 out of 10 (70%) epitopes elicited polyfunctional T-cell responses (secretion of INF-α, TNF-α, and/or IL-2) from either CD4+ or CD8+ T-cells. Conclusion: To identify which predicted epitopes within the peptides pools stimulated the T-cell responses, we deconvoluted all the pools by either ex vivo and in vitro expansion. Ex vivo IFN-α production was detected in 1 (15-mer) peptide out of 15 (6.7%) and in 4 (9-10-mer) peptides out of 22 (18.2%). After expansion with single peptides, of 22 (9-10-mer) peptides tested, CD8+ T-cells were reactive against 13 peptides (59%), while CD4+ responses were seen in response to 11 of 15 (15-16-mer) peptides tested. Both CD4+ and CD8+ T-cell responses were polyfunctional. The PGV001 vaccine in our first patient showed both safety and immunogenicity, eliciting both CD4+ and CD8+ responses to the vaccine peptides. As we are enrolling additional patients, the information learned from this clinical trial will instruct the next generation of MTA-based vaccines, future development of immunotherapeutic approaches and rational combinations.

Citation Format: Ana B. Blazquez, Alex Rubinsteyn, Julia Kodysh, John P. Finnigan, Thomas Marron, Rachel L. Sabado, Marcia Meseck, Timothy J. O'Donnell, Jeffrey Hammerbacher, Michael Donovan, John Holt, Milind Mahajan, John Mandeli, Krysztof Misiukiewicz, Eric M. Genden, Brett A. Milles, Hooman Khorasani, Peter R. Dottino, Hanna Irie, Amy B. Tiersten, Elisa R. Port, Andrea S. Wolf, Hern J. Cho, Ashutosh Tewari, Samir S. Parekh, Sujit Nair, Matthew D. Galsky, William K. Oh, Sacha Gnjatic, Eric E. Schadt, Phillip A. Friedlander, Nina Bhardwaj. A phase I study of the safety and immunogenicity of a multipeptide personalized genomic vaccine in the adjuvant treatment of solid cancers [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A005.

Myeloid-derived suppressor cells as a vehicle for tumor-specific oncolytic viral therapy

One of the several impediments to effective oncolytic virus therapy of cancer remains a lack of tumor-specific targeting. Myeloid-derived suppressor cells (MDSC) are immature myeloid cells induced by tumor factors in tumor-bearing hosts. The biodistribution kinetics of MDSC and other immune cell types in a murine hepatic colon cancer model was investigated through the use of tracking markers and MRI. MDSCs were superior to other immune cell types in preferential migration to tumors in comparison with other tissues. On the basis of this observation, we engineered a strain of vesicular stomatitis virus (VSV), an oncolytic rhabdovirus that bound MDSCs and used them as a delivery vehicle. Improving VSV-binding efficiency to MDSCs extended the long-term survival of mice bearing metastatic colon tumors compared with systemic administration of wild-type VSV alone. Survival was further extended by multiple injections of the engineered virus without significant toxicity. Notably, direct tumor killing was accentuated by promoting MDSC differentiation towards the classically activated M1-like phenotype. Our results offer a preclinical proof-of-concept for using MDSCs to facilitate and enhance the tumor-killing activity of tumor-targeted oncolytic therapeutics.

Current good manufacturing practice production of an oncolytic recombinant vesicular stomatitis viral vector for cancer treatment

Vesicular stomatitis virus (VSV) is an oncolytic virus currently being investigated as a promising tool to treat cancer because of its ability to selectively replicate in cancer cells. To enhance the oncolytic property of the nonpathologic laboratory strain of VSV, we generated a recombinant vector [rVSV(MΔ51)-M3] expressing murine gammaherpesvirus M3, a secreted viral chemokine-binding protein that binds to a broad range of mammalian chemokines with high affinity. As previously reported, when rVSV(MΔ51)-M3 was used in an orthotopic model of hepatocellular carcinoma (HCC) in rats, it suppressed inflammatory cell migration to the virus-infected tumor site, which allowed for enhanced intratumoral virus replication leading to increased tumor necrosis and substantially prolonged survival. These encouraging results led to the development of this vector for clinical translation in patients with HCC. However, a scalable current Good Manufacturing Practice (cGMP)-compliant manufacturing process has not been described for this vector. To produce the quantities of high-titer virus required for clinical trials, a process that is amenable to GMP manufacturing and scale-up was developed. We describe here a large-scale (50-liter) vector production process capable of achieving crude titers on the order of 10(9) plaque-forming units (PFU)/ml under cGMP. This process was used to generate a master virus seed stock and a clinical lot of the clinical trial agent under cGMP with an infectious viral titer of approximately 2 × 10(10) PFU/ml (total yield, 1 × 10(13) PFU). The lot has passed all U.S. Food and Drug Administration-mandated release testing and will be used in a phase 1 clinical translational trial in patients with advanced HCC.

The novel role of tyrosine kinase inhibitor in the reversal of immune suppression and modulation of tumor microenvironment for immune-based cancer therapies

In tumor-bearing hosts, myeloid-derived suppressor cells (MDSC) and T regulatory cells (Treg) play important roles in immune suppression, the reversal of which is vitally important for the success of immune therapy. We have shown that ckit ligand is required for MDSC accumulation and Treg development. We hypothesized that sunitinib malate, a receptor tyrosine kinase inhibitor, could reverse MDSC-mediated immune suppression and modulate the tumor microenvironment, thereby improving the efficacy of immune-based therapies. Treatment with sunitinib decreased the number of MDSC and Treg in advanced tumor-bearing animals. Furthermore, it not only reduced the suppressive function of MDSCs but also prevented tumor-specific T-cell anergy and Treg development. Interestingly, sunitinib treatment resulted in reduced expression of interleukin (IL)-10, transforming growth factor-beta, and Foxp3 but enhanced expression of Th1 cytokine IFN-gamma and increased CTL responses in isolated tumor-infiltrating leukocytes. A significantly higher percentage and infiltration of CD8 and CD4 cells was detected in tumors of sunitinib-treated mice when compared with control-treated mice. More importantly, the expression of negative costimulatory molecules CTLA4 and PD-1 in both CD4 and CD8 T cells, and PDL-1 expression on MDSC and plasmacytoid dendritic cells, was also significantly decreased by sunitinib treatment. Finally, sunitinib in combination with our immune therapy protocol (IL-12 and 4-1BB activation) significantly improves the long-term survival rate of large tumor-bearing mice. These data suggest that sunitinib can be used to reverse immune suppression and as a potentially useful adjunct for enhancing the efficacy of immune-based cancer therapy for advanced malignancies.

Enhanced oncolytic potency of vesicular stomatitis virus through vector-mediated inhibition of NK and NKT cells

Recombinant oncolytic viruses represent a promising alternative option for the treatment of malignant cancers. We have reported earlier the safety and efficacy of recombinant vesicular stomatitis virus (VSV) vectors in a rat model of hepatocellular carcinoma (HCC). However, the full potential of VSV therapy is limited by a sudden decline in intratumoral virus replication observed early after viral administration, a phenomenon that coincides with an accumulation of inflammatory cells within infected lesions. To overcome the antiviral function of these cells, we present a recombinant virus, rVSV-UL141, which expresses a protein from human cytomegalovirus known to downregulate the natural killer (NK) cell-activating ligand CD155. The modified vector resulted in an inhibition of NK cell recruitment in vitro, as well as decreased intratumoral accumulations of NK and NKT cells in vivo. Administration of rVSV-UL141 through hepatic artery infusion in immune-competent Buffalo rats harboring orthotopic, multi-focal HCC lesions resulted in a one-log elevation of intratumoral virus replication over a control rVSV vector, which translated to enhance tumor necrosis and substantial prolongation of survival. Moreover, these results were achieved in the absence of apparent toxicities. The present study suggests the applicability of this strategy for the development of effective and safe oncolytic agents to treat multi-focal HCC, and potentially a multitude of other cancers, in the future.

FoxO1 mediates insulin-dependent regulation of hepatic VLDL production in mice

Excessive production of triglyceride-rich VLDL is attributable to hypertriglyceridemia. VLDL production is facilitated by microsomal triglyceride transfer protein (MTP) in a rate-limiting step that is regulated by insulin. To characterize the underlying mechanism, we studied hepatic MTP regulation by forkhead box O1 (FoxO1), a transcription factor that plays a key role in hepatic insulin signaling. In HepG2 cells, MTP expression was induced by FoxO1 and inhibited by exposure to insulin. This effect correlated with the ability of FoxO1 to bind and stimulate MTP promoter activity. Deletion or mutation of the FoxO1 target site within the MTP promoter disabled FoxO1 binding and resulted in abolition of insulin-dependent regulation of MTP expression. We generated mice that expressed a constitutively active FoxO1 transgene and found that increased FoxO1 activity was associated with enhanced MTP expression, augmented VLDL production, and elevated plasma triglyceride levels. In contrast, RNAi-mediated silencing of hepatic FoxO1 was associated with reduced MTP and VLDL production in adult mice. Furthermore, we found that hepatic FoxO1 abundance and MTP production were increased in mice with abnormal triglyceride metabolism. These data suggest that FoxO1 mediates insulin regulation of MTP production and that augmented MTP levels may be a causative factor for VLDL overproduction and hypertriglyceridemia in diabetes.

FoxO1 mediates insulin-dependent regulation of hepatic VLDL production in mice

Excessive production of triglyceride-rich VLDL is attributable to hypertriglyceridemia. VLDL production is facilitated by microsomal triglyceride transfer protein (MTP) in a rate-limiting step that is regulated by insulin. To characterize the underlying mechanism, we studied hepatic MTP regulation by forkhead box O1 (FoxO1), a transcription factor that plays a key role in hepatic insulin signaling. In HepG2 cells, MTP expression was induced by FoxO1 and inhibited by exposure to insulin. This effect correlated with the ability of FoxO1 to bind and stimulate MTP promoter activity. Deletion or mutation of the FoxO1 target site within the MTP promoter disabled FoxO1 binding and resulted in abolition of insulin-dependent regulation of MTP expression. We generated mice that expressed a constitutively active FoxO1 transgene and found that increased FoxO1 activity was associated with enhanced MTP expression, augmented VLDL production, and elevated plasma triglyceride levels. In contrast, RNAi-mediated silencing of hepatic FoxO1 was associated with reduced MTP and VLDL production in adult mice. Furthermore, we found that hepatic FoxO1 abundance and MTP production were increased in mice with abnormal triglyceride metabolism. These data suggest that FoxO1 mediates insulin regulation of MTP production and that augmented MTP levels may be a causative factor for VLDL overproduction and hypertriglyceridemia in diabetes.

rVSV(M Delta 51)-M3 is an effective and safe oncolytic virus for cancer therapy

Oncolytic vesicular stomatitis virus (VSV) is being developed as a novel therapeutic agent for cancer treatment, although it is toxic in animals when administered systemically at high doses. Its safety can be substantively improved by an M Delta 51 deletion in the viral genome, and yet VSV(M Delta 51) induces a much greater, robust cellular inflammatory response in the host than wild-type VSV, which severely attenuates its oncolytic potency. We have reported that the oncolytic potency of wild-type VSV can be enhanced by vector-mediated expression of a heterologous viral gene that suppresses cellular inflammatory responses in the lesions. To develop an effective and safe VSV vector for cancer treatment, we tested the hypothesis that the oncolytic potency of VSV(M Delta 51) can be substantively elevated by vector-mediated expression of M3, a broad-spectrum and high-affinity chemokine-binding protein from murine gammaherpesvirus-68. The recombinant vector rVSV(M Delta 51)-M3 was used to treat rats bearing multifocal lesions (1-10 mm in diameter) of hepatocellular carcinoma (HCC) in their liver by hepatic artery infusion. Treatment led to a significant reduction of neutrophil and natural killer cell accumulation in the lesions, a 2-log elevation of intratumoral viral titer, substantively enhanced tumor necrosis, and prolonged animal survival with a 50% cure rate. Importantly, there were no apparent systemic and organ toxicities in the treated animals. These results indicate that the robust cellular inflammatory responses induced by VSV(M Delta 51) in HCC lesions can be overcome by vector-mediated intratumoral M3 expression, and that rVSV(M Delta 51)-M3 can be developed as an effective and safe oncolytic agent to treat advanced HCC patients in the future.

Rejection of metastatic 4T1 breast cancer by attenuation of Treg cells in combination with immune stimulation

4T1 breast carcinoma is a highly malignant and poorly immunogenic murine tumor model that resembles advanced breast cancer in humans, and is refractory to most immune stimulation-based treatments. We hypothesize that the ineffectiveness of immune stimulatory treatment is mediated by the suppressive effects of CD4(+)CD25(+) regulatory T (Treg) cells, which can be attenuated by engaging the glucocorticoid-induced tumor necrosis factor receptor family-related protein with its natural ligand (GITRL); further, combination treatment with existing immune stimulation regimens will augment anti-tumor immunity and eradicate metastatic 4T1 tumors in mice.A soluble homodimeric form of mouse GITRL (mIg-mGITRLs) was molecularly constructed and used to treat orthotopic 4T1 tumors established in immune-competent, syngeneic Balb/c mice. When applied in combination with adenovirus-mediated intratumoral murine granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin-12 (IL-12) gene delivery plus systemic 4-1BB activation, mIg-mGITRLs attenuated the immune-suppressive function of splenic Treg cells, which led to elevated interferon-gamma (IFN-gamma) production, tumor-specific cytolytic T-cell activities, tumor rejection and long-term survival in 65% of the animals without apparent toxicities. The results demonstrate that addition of mIg-mGITRLs to an immune-stimulatory treatment regimen significantly improved long-term survival without apparent toxicity, and could potentially be clinically translated into an effective and safe treatment modality for metastatic breast cancer in patients.

Aberrant Forkhead box O1 function is associated with impaired hepatic metabolism

FoxO1 plays an important role in mediating the effect of insulin on hepatic metabolism. Increased FoxO1 activity is associated with reduced ability of insulin to regulate hepatic glucose production. However, the underlying mechanism and physiology remain unknown. We studied the effect of FoxO1 on the ability of insulin to regulate hepatic metabolism in normal vs. insulin-resistant liver under fed and fasting conditions. FoxO1 gain of function, as a result of adenovirus-mediated or transgenic expression, augmented hepatic gluconeogenesis, accompanied by decreased glycogen content and increased fat deposition in liver. Mice with excessive FoxO1 activity exhibited impaired glucose tolerance. Conversely, FoxO1 loss of function, caused by hepatic production of its dominant-negative variant, suppressed hepatic gluconeogenesis, resulting in enhanced glucose disposal and improved insulin sensitivity in db/db mice. FoxO1 expression becomes deregulated, culminating in increased nuclear localization and accounting for its increased transcription activity in livers of both high fat-induced obese mice and diabetic db/db mice. Increased FoxO1 activity resulted in up-regulation of hepatic peroxisome proliferator-activated receptor-gamma coactivator-1beta, fatty acid synthase, and acetyl CoA carboxylase expression, accounting for increased hepatic fat infiltration. These data indicate that hepatic FoxO1 deregulation impairs the ability of insulin to regulate hepatic metabolism, contributing to the development of hepatic steatosis and abnormal metabolism in diabetes.

The systemic administration of Ig-4-1BB ligand in combination with IL-12 gene transfer eradicates hepatic colon carcinoma

We have previously shown that the local-membrane bound 4-1BB ligand and IL-12 gene transfer induced a significant antitumor response in a mouse colon carcinoma model. However, a high viral dose was required in order to achieve the best efficacy. In this study, we hypothesize that the systemic administration of soluble Ig-4-1BB ligand can give rise to better T-cell immune activation than local gene delivery. With potential clinical applications in mind, we further compare whether the natural 4-1BB ligand fused to mouse IgG2a (Ig-4-1BBL) would be as effective as the agonistic anti-4-1BB antibody. The dimeric form of Ig-4-1BBL was purified from HeLa cells transduced with a recombinant adenovirus (ADV/Ig-4-1BBL) expressing Ig-4-1BBL. Functional activity was confirmed by the ligand's ability to bind to activated splenic T cells or bone marrow (BM)-derived dendritic cells (DCs) that express 4-1BB receptor. The soluble Ig-4-1BBL efficiently costimulated CD3-activated T-cell proliferation in vitro. More importantly, it induced tumor-specific CTLs as effectively as the agonistic anti-4-1BB antibody. When combined with IL-12 gene transfer, systemic administration of the Ig-4-1BBL proved to be more potent than local gene delivery. In addition, the Ig-4-1BBL is as potent as the agonistic anti-4-1BB antibody for the treatment of hepatic MCA26 colon carcinoma, resulting in 50% complete tumor regression and long-term survival. In long-term surviving mice, both treatment modalities induced persistent tumor-specific CTL activity. In summary, these results suggest that the systemic delivery of Ig-4-1BBL can generate a better antitumor response than local gene delivery. Ig-4-1BBL had equivalent biological functions when compared to the agonistic anti-4-1BB antibody. Thus, soluble 4-1BBL dimmer can be developed as a promising agent for cancer therapy in humans.

Increased hepatic levels of the insulin receptor inhibitor, PC-1/NPP1, induce insulin resistance and glucose intolerance

The ectoenzyme, plasma cell membrane glycoprotein-1 (PC-1), is an insulin receptor (IR) inhibitor that is elevated in cells and tissues of insulin-resistant humans. However, the effects of PC-1 overexpression on insulin action have not been studied in animal models. To produce mice with overexpression of PC-1 in liver, a key glucose regulatory organ in this species, we injected them with a PC-1 adenovirus vector that expresses human PC-1. Compared with controls, these mice had two- to threefold elevations of PC-1 content in liver but no changes in other tissues such as skeletal muscle. In liver of PC-1 animals, insulin-stimulated IR tyrosine kinase and Akt/protein kinase B activation were both decreased. In this tissue, the IR-dependent nuclear factor Foxo1 was increased along with two key gluconeogenic enzymes, glucose-6-phosphatase and phosphenolpyruvate carboxykinase. The PC-1 animals had 30-40 mg/dl higher glucose levels and twofold higher insulin levels. During glucose tolerance tests, these animals had peak glucose levels that were >100 mg/dl higher than those of controls. These in vivo data support the concept, therefore, that PC-1 plays a role in insulin resistance and suggest that animals with overexpression of human PC-1 in liver may be interesting models to investigate this pathological process.

Foxo1 mediates insulin action on apoC-III and triglyceride metabolism

The apolipoprotein apoC-III plays an important role in plasma triglyceride metabolism. It is predominantly produced in liver, and its hepatic expression is inhibited by insulin. To elucidate the inhibitory mechanism of insulin in apoC-III expression, we delivered forkhead box O1 (Foxo1) cDNA to hepatocytes by adenovirus-mediated gene transfer. Foxo1 stimulated hepatic apoC-III expression and correlated with the ability of Foxo1 to bind to its consensus site in the apoC-III promoter. Deletion or mutation of the Foxo1 binding site abolished insulin response and Foxo1-mediated stimulation. Likewise, Foxo1 also mediated insulin action on intestinal apoC-III expression in enterocytes. Furthermore, elevated Foxo1 production in liver augmented hepatic apoC-III expression, resulting in increased plasma triglyceride levels and impaired fat tolerance in mice. Transgenic mice expressing a constitutively active Foxo1 allele exhibited hypertriglyceridemia. Moreover, we show that hepatic Foxo1 expression becomes deregulated as a result of insulin deficiency or insulin resistance, culminating in significantly elevated Foxo1 production, along with its skewed nuclear distribution, in livers of diabetic NOD or db/db mice. While loss of insulin response is associated with unrestrained apoC-III production and impaired triglyceride metabolism, these data suggest that Foxo1 provides a molecular link between insulin deficiency or resistance and aberrant apoC-III production in the pathogenesis of diabetic hypertriglyceridemia.

Elevated vascular endothelial growth factor production in islets improves islet graft vascularization

Successful islet transplantation depends on the infusion of sufficiently large quantities of islets, of which only approximately 30% become stably engrafted. Rapid and adequate revascularization of transplanted islets is important for islet survival and function. Delayed and insufficient revascularization can deprive islets of oxygen and nutrients, resulting in islet cell death and early graft failure. To improve islet revascularization, we delivered human vascular endothelial growth factor (VEGF) cDNA to murine islets, followed by transplantation under the renal capsule in diabetic mice. Diabetic animals receiving a marginal mass of 300 islets that were pretransduced with a VEGF vector exhibited near normoglycemia. In contrast, diabetic mice receiving an equivalent number of islets that were transduced with a control vector remained hyperglycemic. Immunohistochemistry with anti-insulin and anti-CD31 antibodies revealed a relatively higher insulin content and greater degree of microvasculature in the VEGF vector-transduced islet grafts, which correlated with significantly improved blood glucose profiles and enhanced insulin secretion in response to glucose challenge in this group of diabetic recipient mice. These results demonstrate that VEGF production in islets stimulates graft angiogenesis and enhances islet revascularization. This mechanism might be explored as a novel strategy to accelerate islet revascularization and improve long-term survival of functional islet mass posttransplantation.

Inhibition of Foxo1 function is associated with improved fasting glycemia in diabetic mice

Excessive hepatic glucose production is a contributing factor to fasting hyperglycemia in diabetes. Insulin suppresses hepatic glucose production by inhibiting the expression of two gluconeogenic enzymes, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G-6-Pase). The forkhead transcription factor Foxo1 has been implicated as a mediator of insulin action in regulating hepatic gluconeogenesis, and a Foxo1 mutant (Foxo1-Delta256), devoid of its carboxyl domain, has been shown to interfere with Foxo1 function and inhibit gluconeogenic gene expression in cultured cells. To study the effect of Foxo1-Delta256 on glucose metabolism in animals, the Foxo1-Delta256 cDNA was delivered to the livers of mice by adenovirus-mediated gene transfer. Hepatic Foxo1-Delta256 production resulted in inhibition of gluconeogenic activity, as evidenced by reduced PEPCK and G-6-Pase expression in the liver. Mice treated with the Foxo1-Delta256 vector exhibited significantly reduced blood glucose levels. In contrast, blood glucose levels in control vector-treated animals remained unchanged, which coincided with the lack of alterations in the expression levels of PEPCK and G-6-Pase. When tested in diabetic db/db mice, hepatic production of Foxo1-Delta256 was shown to reduce fasting hyperglycemia. Furthermore, we showed that hepatic Foxo1 expression was deregulated as a result of insulin resistance in diabetic mice and that Foxo1-Delta256 interfered with Foxo1 function via competitive binding to target promoters. These results demonstrated that functional inhibition of Foxo1, caused by hepatic expression of its mutant, is associated with reduced hepatic gluconeogenic activity and improved fasting glycemia in diabetic mice.

IFN-gamma sensitization of prostate cancer cells to Fas-mediated death: a gene therapy approach

While human prostate cancers and cell lines express Fas, most of these cell lines are resistant to Fas-mediated death. In the present studies we addressed the ability of IFN-gamma to influence Fas-mediated cell death in prostate cancer cells. In vitro exposure of the human cell lines LNCaP and PC3 and the mouse cell line RM-1 to agonist anti-Fas antibody and/or soluble Fas ligand resulted in killing of only PC3 cells. However, preincubation with IFN-gamma resulted in synergistic killing in all three cell lines. In vitro treatment of RM-1 with a replication-incompetent adenovirus expressing mouse FasL (Ad.FasL) resulted in maximal cell kill near 40%, which correlated with baseline Fas expression. The addition of IFN-gamma enhanced cell kill to a degree consistent with the resulting higher levels of Fas and maintained synergistic killing at very low doses of vector. Co-inoculation of orthotopic RM-1 primary tumors with Ad.mFasL and an adenovirus expressing mouse IL-12 (Ad.mIL-12) to drive host production of IFN-gamma negated the survival advantage of Ad.mIL-12 alone. However, the staggered injection of Ad.mIL-12 and Ad.FasL achieved almost threefold higher levels of apoptosis in primary tumor tissue and doubled median survival. Therefore, IFN-gamma is capable of bestowing increased sensitivity to Fas-mediated cell death in prostate cancer cells and, in a gene therapy approach, may define a powerful tool to treat prostate cancers.

Adenovirus-mediated expression of glucokinase in the liver as an adjuvant treatment for type 1 diabetes

Glucokinase (GK) plays a crucial role in hepatic glucose disposal. Its activity is decreased in patients with maturity-onset diabetes of the young and in some animal models of diabetes. We investigated the feasibility of manipulating GK expression as an adjuvant treatment for type 1 diabetes, using an E1/E3-deleted adenoviral vector (Ad.EF1(alpha)GK) delivered to the liver of streptozotocin-induced type 1 diabetic rats. First, we studied the metabolic impact of constitutive glucokinase expression in the absence of insulin. Normal blood glucose levels were observed after gene transfer, and glucose tolerance was substantially enhanced compared with diabetic control animals, suggesting that hepatic GK expression is a feasible mechanism to enhance glucose disposal. In a second study we administered Ad.EF1(alpha)GK together with subcutaneous insulin injections to determine whether the combined action of insulin plus GK activity would provide better glucose homeostasis than insulin treatment alone. This combination approach resulted in constant, near-normal glucose values under fed conditions. Furthermore, the animals stayed in the normoglycemic range after an overnight fast, indicating that the risk to develop hypoglycemia is not increased by expression of GK. Alterations of other metabolic routes were observed, suggesting that insulin-regulated expression of GK may be necessary to use the strategy as a treatment of type 1 diabetes.

Functional genomic analysis of type II IL-1beta decoy receptor: potential for gene therapy in human arthritis and inflammation

Gene expression arrays show that human epithelial cells and human arthritis-affected cartilage lack detectable amounts of mRNA for IL-1 antagonizing molecules: IL-1Ra and IL-1RII, but constitutively express IL-1. Functional genomic analysis was performed by reconstituting human IL-1RII expression in various IL-1RII-deficient cell types to examine its antagonist role using gene therapy approaches. Adenovirus-expressing IL-1RII when transduced into human and bovine chondrocytes, human and rabbit synovial cells, human epithelial cells, and rodent fibroblasts expressed membrane IL-1RII and spontaneously released functional soluble IL-1RII. The IL-1RII(+) (but not IL-1RII(-)) cells were resistant to IL-1beta-induced, NO, PGE(2), IL-6, and IL-8 production or decreased proteoglycan synthesis. IL-1RII inhibited the function of IL-1 in chondrocytes and IL-1- and TNF-alpha-induced inflammatory mediators in human synovial and epithelial cells. IL-1RII(+) chondrocytes were more resistant to induction of NO and PGE(2) by IL-1beta compared with IL-1RII(-) cells incubated with a 10-fold (weight) excess of soluble type II IL-1R (sIL-1RII) protein. In cocultures, IL-1RII(+) synovial cells released sIL-1RII, which in a paracrine fashion protected chondrocytes from the effects of IL-1beta. Furthermore, IL-1RII(+) (but not IL-1RII(-)) chondrocytes when transplanted onto human osteoarthritis-affected cartilage in vitro, which showed spontaneous release of sIL-1RII for 20 days, inhibited the spontaneous production of NO and PGE(2) in cartilage in ex vivo. In summary, reconstitution of IL-1RII in IL-1RII(-) cells using gene therapy approaches significantly protects cells against the autocrine and paracrine effects of IL-1 at the signaling and transcriptional levels.

Basal insulin gene expression significantly improves conventional insulin therapy in type 1 diabetic rats

Although a conventional insulin regimen for type 1 diabetes with twice-daily insulin injections is effective in preventing postprandial blood glucose excursions, this treatment is limited by its inadequate control of fasting hyperglycemia. Alternatively, sustained basal hepatic insulin gene expression has been shown to result in fasting normoglycemia in type 1 diabetic rats, although the treated animals still exhibited moderate postprandial hyperglycemia. To test the hypothesis that basal hepatic insulin production can be used as an auxiliary treatment to conventional insulin therapy for achieving better glycemic control, streptozotocin-induced diabetic rats were treated with twice-daily insulin injections, basal hepatic insulin production, or both in combination. Diabetic rats treated by conventional insulin therapy still suffered from fasting hyperglycemia, but when complemented with basal hepatic insulin production, near-normoglycemia under both fed and fasting conditions was achieved without fasting hypoglycemia. In addition, the combination-treated animals showed significantly enhanced glucose tolerance and markedly improved profiles in lipid metabolism. Furthermore, the combination treatment reduced the elevated fructosamine, glycated hemoglobin, and advanced glycation end products concentrations to normal. These results provide a proof of concept for basal hepatic insulin production as an adjuvant treatment to conventional insulin therapy in type 1 diabetes.

Hepatic insulin expression improves glycemic control in type 1 diabetic rats

Low levels of hepatic insulin production have been shown to prevent lethal ketoacidosis associated with type 1 diabetes. To assess the beneficial effects of sustained hepatic production of insulin on glycemic control in type 1 diabetes, we have employed the adenovirus-mediated gene delivery system to transfer an engineered rat preproinsulin gene to the livers of streptozotocin-induced diabetic nude rats. Hepatic insulin production resulted in the reduction of blood glucose in treated diabetic rats, the degree of blood glucose reduction correlated with both the vector dose and the level of hepatic insulin expression. At moderate vector doses, 0.3-0.7 ng/ml of plasma insulin was produced in treated diabetic animals, resulting in significant reduction of nonfasting hyperglycemia and improvement in glucose tolerance. Furthermore, these animals maintained euglycemia after 12-h fast. At higher vector doses, greater than 1 ng/ml of plasma insulin was produced, completely reversing nonfasting hyperglycemia in treated rats. However, all of the treated animals developed severe hypoglycemia upon fasting. This study has defined the maximal tolerable level of hepatic insulin production that is sufficient to reduce the degree and ameliorate the adverse effects of nonfasting hyperglycemia without risk of fasting hypoglycemia in type 1 diabetic rats.

Glucose-stimulated and self-limiting insulin production by glucose 6-phosphatase promoter driven insulin expression in hepatoma cells

The liver is an attractive target organ for insulin gene expression in type 1 diabetes as it contains appropriate cellular mechanisms of regulated gene expression in response to blood glucose and insulin. We hypothesize that insulin production regulated by both glucose and insulin may be achieved using the promoter of the glucose 6-phosphatase gene (G6Pase), the expression of which in the liver is induced by glucose and suppressed by insulin. Recombinant adenoviral vectors expressing the reporter gene CAT or insulin under transcriptional direction of the G6Pase promoter were constructed. Glucose-stimulated as well as self-limiting insulin production was achieved in vector-transduced hepatoma cells in which expression of the insulin gene was controlled by the G6Pase promoter. While insulin strongly inhibited the G6Pase promoter activity under low glucose conditions, its inhibitory capacity was attenuated when glucose levels were elevated. At the physiologic glucose level of 5.5 mM glucose, vector-transduced hepatoma cells produced a self-limited level of insulin at approximately 0.2-0.3 ng/ml, which is within the range of fasting levels of insulin in normal animals. These results indicate that the G6Pase promoter possesses desirable features and may be developed for regulated hepatic insulin gene expression in type 1 diabetes.