Preclinical characterization and clinical translation of pharmacodynamic markers for MK-5890: a human CD27 activating antibody for cancer immunotherapy.

BACKGROUND: Immune checkpoint inhibitors (ICI) have radically changed cancer therapy, but most patients with cancer are unresponsive or relapse after treatment. MK-5890 is a CD27 agonist antibody intended to complement ICI therapy. CD27 is a member of the tumor necrosis factor receptor superfamily that plays a critical role in promoting responses of T cells, B cells and NK cells. METHODS: Anti-CD27 antibodies were generated and selected for agonist activity using NF-кB luciferase reporter assays. Antibodies were humanized and characterized for agonism using in vitro T-cell proliferation assays. The epitope recognized on CD27 by MK-5890 was established by X-ray crystallography. Anti-tumor activity was evaluated in a human CD27 knock-in mouse. Preclinical safety was tested in rhesus monkeys. Pharmacodynamic properties were examined in mouse, rhesus monkeys and a phase 1 dose escalation clinical study in patients with cancer. RESULTS: Humanized anti-CD27 antibody MK-5890 (hIgG1) was shown to bind human CD27 on the cell surface with sub-nanomolar potency and to partially block binding to its ligand, CD70. Crystallization studies revealed that MK-5890 binds to a unique epitope in the cysteine-rich domain 1 (CRD1). MK-5890 activated CD27 expressed on 293T NF-κB luciferase reporter cells and, conditional on CD3 stimulation, in purified CD8+ T cells without the requirement of crosslinking. Functional Fc-receptor interaction was required to activate CD8+ T cells in an ex vivo tumor explant system and to induce antitumor efficacy in syngeneic murine subcutaneous tumor models. MK-5890 had monotherapy efficacy in these models and enhanced efficacy of PD-1 blockade. MK-5890 reduced in an isotype-dependent and dose-dependent manner circulating, but not tumor-infiltrating T-cell numbers in these mouse models. In rhesus monkey and human patients, reduction in circulating T cells was transient and less pronounced than in mouse. MK-5890 induced transient elevation of chemokines MCP-1, MIP-1α, and MIP-1ß in the serum of mice, rhesus monkeys and patients with cancer. MK-5890 was well tolerated in rhesus monkeys and systemic exposure to MK-5890 was associated with CD27 occupancy at all doses. CONCLUSIONS: MK-5890 is a novel CD27 agonistic antibody with the potential to complement the activity of PD-1 checkpoint inhibition in cancer immunotherapy and is currently undergoing clinical evaluation.

Safety and immunogenicity of intramuscular, single-dose V590 (rVSV-SARS-CoV-2 Vaccine) in healthy adults: Results from a phase 1 randomised, double-blind, placebo-controlled, dose-ranging trial.

BACKGROUND: Vaccines against COVID-19 are needed to overcome challenges associated with mitigating the global pandemic. We report the safety and immunogenicity of V590, a live recombinant vesicular stomatitis virus-based COVID-19 vaccine candidate. METHODS: In this placebo-controlled, double-blind, three-part phase 1 study, healthy adults were randomised to receive a single intramuscular dose of vaccine or placebo. In Part 1, younger (18-54 years) and, in Part 2, older (≥55 years) adults seronegative for SARS-CoV-2 nucleocapsid received one of four V590 dose levels (5.00 × 105; 2.40 × 106; 1.15 × 107; or 5.55 × 107 plaque-forming units [pfu]) or placebo. In Part 3, a single V590 dose level (5.55 × 107 pfu) or placebo was administered to younger SARS-CoV-2 seropositive adults. Primary endpoints included adverse events (AEs) and for Parts 1 and 2 anti-SARS-CoV-2 serum neutralising antibody responses measured by 50% plaque reduction neutralisation (PRNT50) assay at Day 28. Registration NCT04569786 [P001-02]. FINDINGS: 232 participants were randomised and 219 completed the study. In seronegative participants, anti-SARS-CoV-2 spike-specific antibody responses to V590 were low and comparable to placebo across the lower dose levels. At the highest dose level (5.55 × 107 pfu), anti-SARS-CoV-2 spike-specific PRNT50 was 2.3-fold higher than placebo. The most frequently reported AEs were injection-site pain (38.4%), headache (15.1%) and fatigue (13.4%). INTERPRETATION: V590 was generally well-tolerated. However, Day 28 anti-SARS-Cov-2 spike-specific antibody responses in seronegative participants following a single intramuscular administration of V590 were not sufficient to warrant continued development. FUNDING: The study was funded by Merck Sharp & Dohme LLC., a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

2021 White Paper on Recent Issues in Bioanalysis: ISR for Biomarkers, Liquid Biopsies, Spectral Cytometry, Inhalation/Oral & Multispecific Biotherapeutics, Accuracy/LLOQ for Flow Cytometry (Part 2 - Recommendations on Biomarkers/CDx Assays Development & Validation, Cytometry Validation & Innovation, Biotherapeutics PK LBA Regulated Bioanalysis, Critical Reagents & Positive Controls Generation).

The 15th edition of the Workshop on Recent Issues in Bioanalysis (15th WRIB) was held on 27 September to 1 October 2021. Even with a last-minute move from in-person to virtual, an overwhelmingly high number of nearly 900 professionals representing pharma and biotech companies, contract research organizations (CROs), and multiple regulatory agencies still eagerly convened to actively discuss the most current topics of interest in bioanalysis. The 15th WRIB included three Main Workshops and seven Specialized Workshops that together spanned 1 week in order to allow exhaustive and thorough coverage of all major issues in bioanalysis, biomarkers, immunogenicity, gene therapy, cell therapy and vaccines. Moreover, in-depth workshops on biomarker assay development and validation (BAV) (focused on clarifying the confusion created by the increased use of the term "context of use" [COU]); mass spectrometry of proteins (therapeutic, biomarker and transgene); state-of-the-art cytometry innovation and validation; and critical reagent and positive control generation were the special features of the 15th edition. This 2021 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop, and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2021 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 2) covers the recommendations on ISR for Biomarkers, Liquid Biopsies, Spectral Cytometry, Inhalation/Oral & Multispecific Biotherapeutics, Accuracy/LLOQ for Flow Cytometry. Part 1A (Endogenous Compounds, Small Molecules, Complex Methods, Regulated Mass Spec of Large Molecules, Small Molecule, PoC), Part 1B (Regulatory Agencies' Inputs on Bioanalysis, Biomarkers, Immunogenicity, Gene & Cell Therapy and Vaccine) and Part 3 (TAb/NAb, Viral Vector CDx, Shedding Assays; CRISPR/Cas9 & CAR-T Immunogenicity; PCR & Vaccine Assay Performance; ADA Assay Comparability & Cut Point Appropriateness) are published in volume 14 of Bioanalysis, issues 9 and 11 (2022), respectively.

Combination of EP4 antagonist MF-766 and anti-PD-1 promotes anti-tumor efficacy by modulating both lymphocytes and myeloid cells.

Prostaglandin E2 (PGE2), an arachidonic acid pathway metabolite produced by cyclooxygenase (COX)-1/2, has been shown to impair anti-tumor immunity through engagement with one or more E-type prostanoid receptors (EP1-4). Specific targeting of EP receptors, as opposed to COX-1/2 inhibition, has been proposed to achieve preferential antagonism of PGE2-mediated immune suppression. Here we describe the anti-tumor activity of MF-766, a potent and highly selective small-molecule inhibitor of the EP4 receptor. EP4 inhibition by MF-766 synergistically improved the efficacy of anti-programmed cell death protein 1 (PD-1) therapy in CT26 and EMT6 syngeneic tumor mouse models. Multiparameter flow cytometry analysis revealed that treatment with MF-766 promoted the infiltration of CD8+ T cells, natural killer (NK) cells and conventional dendritic cells (cDCs), induced M1-like macrophage reprogramming, and reduced granulocytic myeloid-derived suppressor cells (MDSC) in the tumor microenvironment (TME). In vitro experiments demonstrated that MF-766 restored PGE2-mediated inhibition of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α production in THP-1 cells and human blood, and PGE2-mediated inhibition of interleukin (IL)-2-induced interferon (IFN)-γ production in human NK cells. MF-766 reversed the inhibition of IFN-γ in CD8+ T-cells by PGE2 and impaired suppression of CD8+ T-cells induced by myeloid-derived suppressor cells (MDSC)/PGE2. In translational studies using primary human tumors, MF-766 enhanced anti-CD3-stimulated IFN-γ, IL-2, and TNF-α production in primary histoculture and synergized with pembrolizumab in a PGE2 high TME. Our studies demonstrate that the combination of EP4 blockade with anti-PD-1 therapy enhances antitumor activity by differentially modulating myeloid cell, NK cell, cDC and T-cell infiltration profiles.

Phase I Study of MK-4166, an Anti-human Glucocorticoid-Induced TNF Receptor Antibody, Alone or with Pembrolizumab in Advanced Solid Tumors.

PURPOSE: In this first-in-human phase I study (NCT02132754), we explored MK-4166 [humanized IgG1 agonist mAb targeting glucocorticoid-induced TNF receptor (GITR)] with and without pembrolizumab in advanced solid tumors. PATIENTS AND METHODS: MK-4166 was tested alone (0.0015-900 mg i.v. every 3 weeks for four doses) or with pembrolizumab (200 mg i.v. every 3 weeks for ≤35 doses) in patients with metastatic solid tumors (dose escalation/confirmation) and advanced melanoma (expansion). Primary objectives were to evaluate the safety and tolerability and establish the MTD of MK-4166. Exploratory endpoints were objective response rate (ORR) and T cell-inflamed gene expression profile (GEP) analysis using RNA from baseline tumor samples. RESULTS: A total of 113 patients were enrolled [monotherapy, n = 48; combination therapy, n = 65 (20 in the expansion)]. Forty-six patients (40.7%) had grade ≥3 adverse events, 9 (8.0%) of which were treatment related. No treatment-related deaths were observed. One dose-limiting toxicity event with monotherapy (bladder perforation in patient with neobladder) was considered related to study drug. MTD was not reached. MK-4166 pharmacodynamics showed decreased GITR availability on circulating T cells with increasing doses. One objective response (ORR, 2.2%) was achieved with combination therapy in the dose escalation/confirmation (n = 45). In the expansion, 8 of 13 patients with immune checkpoint inhibitor (ICI)-naïve melanoma achieved a response (ORR, 62%; 95% confidence interval, 32-86; 5 complete responses and 3 partial responses). None of the ICI-pretreated patients (n = 7) responded. High response rates were observed in ICI-naïve patients irrespective of GEP status. CONCLUSIONS: MK-4166 900 mg i.v. every 3 weeks as monotherapy and with pembrolizumab was tolerable. Responses were observed with combination therapy, mostly in patients with ICI-naïve melanoma.

First-in-human phase 1 study of MK-1248, an anti-glucocorticoid-induced tumor necrosis factor receptor agonist monoclonal antibody, as monotherapy or with pembrolizumab in patients with advanced solid tumors.

BACKGROUND: Ligation of glucocorticoid-induced tumor necrosis factor receptor (GITR) decreases regulatory T cell-mediated suppression and enhances T-cell proliferation, effector function, and survival. MK-1248 is a humanized immunoglobulin G4 anti-GITR monoclonal antibody agonist. METHODS: In patients with advanced solid tumors, MK-1248 (starting dose, 0.12 mg) was tested alone and with pembrolizumab (200 mg) according to a 3 + 3 dose escalation design (ClinicalTrials.gov identifier NCT02553499); both treatments were administered intravenously every 3 weeks for ≤4 and ≤35 cycles, respectively. The safety and tolerability, maximum tolerated dose, and pharmacokinetics/pharmacodynamics were explored. RESULTS: Twenty patients received MK-1248 monotherapy; 17 received combination therapy. The most frequent tumor types were colorectal cancer (n = 8), melanoma (n = 6), and renal cell carcinoma (n = 4). MK-1248 was generally well tolerated at the maximum tested doses of 170 (monotherapy) and 60 mg (combination). No dose-limiting toxicities (DLTs) or treatment-related deaths occurred. Adverse events (AEs) occurred in 36 of the 37 patients (97%); the most common were vomiting (n = 13 [35%]), anemia (n = 10 [27%]), and decreased appetite (n = 10 [27%]). Grade 3 to 5 AEs occurred in 19 of the 37 patients (51%). Treatment-related AEs occurred in 18 of the 37 patients (49%): 9 of the 20 patients (45%) on monotherapy and 9 of the 17 patients (53%) on combination therapy. Among the 17 patients receiving combination therapy, 1 achieved a complete response and 2 achieved a partial response, for an objective response rate of 18%; no patients achieved an objective response with monotherapy. The disease control rate (stable disease or better) was 15% with monotherapy and 41% with combination therapy. CONCLUSIONS: MK-1248 was generally well tolerated at doses up to 170 (monotherapy) and 60 mg (combination), with no DLTs or treatment-related deaths. Combination therapy provided limited antitumor responses.

A preliminary study for the assessment of PD-L1 and PD-L2 on circulating tumor cells by microfluidic-based chipcytometry.

AIM: Expression of PD-L1 in the tumor is associated with more favorable responses to anti-PD-1 therapy in multiple cancers. However, obtaining tumor biopsies for PD-L1 interrogation is an invasive procedure and challenging to assess repeatedly as the disease progresses. MATERIALS & METHODS: Here we assess an alternative, minimally invasive approach to analyze blood samples for circulating tumor cells (CTCs) that have broken away from the tumor and entered the periphery. Our approach uses sized-based microfluidic CTC enrichment and subsequent characterization with microfluidic-based cytometry (chipcytometry). CONCLUSION: We demonstrate tumor-cell detection and characterization for PD-L1, and other markers, in both spiked and patient samples. This preliminary communication is the first report using chipcytometry for the characterization of CTCs.

Induction studies with Escherichia coli expressing recombinant interleukin-13 using multi-parameter flow cytometry.

The expression of interleukin-13 (IL13) following induction with IPTG in Escherichia coli results in metabolic changes as indicated by multi-parameter flow cytometry and traditional methods of fermentation profiling (O2 uptake rate, CO2 evolution rate and optical density measurements). Induction early in the rapid growth phase was optimal although this led to lower overall biomass concentrations and lower maximum specific growth rates. In contrast, induction in the mid-rapid growth phase was the most detrimental to cell quality as measured by cytoplamsic membrane depolarisation.

Characterization of the NOD/scid-[Tg]DR1 mouse expressing HLA-DRB1*01 transgene: a model of SCID-hu mouse for vaccine development.

OBJECTIVE: We previously showed enhanced engraftment of human T cells in the transgenic NonObese Diabetic/severe combined immunodeficient (NOD/scid)-DR1 mice, compared to NOD/scid mice. We now characterize their immunobiology, innate immunity, and intrahepatic neonatal engraftment of cord blood mononuclear cells (CBMNC), and test immune responses of these chimeric mice to an experimental cancer vaccine. METHODS: Fluorescence in situ hybridization analysis, blood biochemistry, hematology, and fluorescein-activated cell sorting analyses of cellular subsets were performed on NOD/scid-DR1 mice, in comparison to parental NOD/scid mice. Innate immunity and lifespan were examined. Histology of engrafted tissues and short-term intrahepatic engraftment of CBMNC were performed. Intracellular interferon-gamma (IFN-gamma) production was assessed in mice immunized with cancer vaccine. RESULTS: The DR1 transgene was located on chromosome 5 and no significant changes were observed in blood chemistry, peripheral blood counts, lymphoid subsets, natural killer cell and lipopolysaccharide response, and antigen presentation in the NOD/scid-DR1 mice, compared to NOD/scid mice. Interestingly, NOD/scid-DR1 mice had a significantly longer lifespan (approximately 14 months) than NOD/scid mice (approximately 8.5 months). Engraftment with human cord blood cells resulted in slight changes in the architecture/structure of spleens. No correlation was found between DR1 genotype of the donor CBMNC and extent of engraftment of human T cells. Enhanced engraftment of human cells was observed with intrahepatic injections of CBMNC in neonatal NOD/scid DR1 mice. Intracellular IFN-gamma was detected in human cells, when chimeric mice were immunized with a cancer vaccine. CONCLUSION: NOD/scid-DR1 mice were similar in most of the physiological parameters as the NOD/scid mice, with the exception of longer lifespan. Intrahepatic engraftment of neonatal mice is the preferred protocol of xenotransplantation in this model and the engrafted human cells can respond to a cancer vaccine.

Intra-thymic/splenic engraftment of human T cells in HLA-DR1 transgenic NOD/scid mice.

A HLA-DR1 transgenic mouse (NOD/scid-DR1) was derived by breeding the existing B10.M/J-[Tg]DR1 mouse with the NOD/scid mouse. The intention was to enhance engraftment of human T cells by providing human class II elements in the tissues. Thymus and spleen fragments from adult NOD/scid-DR1 mice were transplanted under the syngeneic kidney capsules, followed by injection of human cord blood mononuclear cells (CBMNC) into transplanted tissues. FACS analyses showed that human T and B cells were consistently detected in the peripheral blood and spleen, of the chimeric mice. An average of 20% of human cells was found in the spleen and the engrafted thymus/spleen tissues. Furthermore, human cells from these tissues could proliferate with anti-human CD3 antibody and these mice could generate humoral and cellular responses to allogeneic human cells. Cytokines, such as IL-10, GMCSF, IFN-gamma, and TNF-alpha were also detected in the supernatants of the cultured human cells from the chimeric mice, when they were stimulated with allogeneic cells. Therefore, a novel mouse model with functional circulating human T and B cells was established that would facilitate the exploration of vaccine, the disease processes of autoimmunity, HIV infection, and human cancer.

A small molecule very late antigen-4 antagonist can inhibit ovalbumin-induced lung inflammation.

A nonpeptidyl small molecule antagonist, compound A, to nonactivated very late antigen-4 (VLA4) was examined in lung inflammation induced by a single dose of ovalbumin challenge. Compound A presented a good pharmacokinetic property, when given intratracheally, and the blood cells from such pharmacokinetic study showed good receptor occupancy of the compound for approximately 8 hours. Compound A was then tested in an ovalbumin-induced airway inflammation model by intranasal or intravenous route of administration. There was a dose-dependent inhibition of eosinophilia in the bronchiolar lavage fluid, when compound A was given intranasally but not when it was given intravenously. For comparison, antibody to VLA4 and another compound, BIO1211, which reacts only with activated VLA4, were examined in this system. Immunohistochemical analyses of the lung tissue substantiated the findings in the bronchiolar lavage fluid. Specific staining of the major basic protein of eosinophils showed peribronchiolar infiltration of eosinophils. Some of these eosinophils were also positive for nitrotyrosine, suggesting activation of eosinophils in the lung interstitium. There was deposition of major basic protein and nitrotyrosine at the base of the perivascular endothelium, indicative of degranulation of eosinophils in the area. After intranasal treatment with compound A, eosinophils in the lungs and their activation products were substantially decreased, documenting its effectiveness in inhibiting lung inflammation.

Functional expression and characterization of macaque C-C chemokine receptor 3 (CCR3) and generation of potent antagonistic anti-macaque CCR3 monoclonal antibodies.

Eosinophils are major effector cells implicated in a number of chronic inflammatory diseases in humans, particularly bronchial asthma and allergic rhinitis. The beta-chemokine receptor C-C chemokine receptor 3 (CCR3) provides a mechanism for the selective recruitment of eosinophils into tissue and thus has recently become an attractive biological target for therapeutic intervention. In order to develop in vivo models of inflammatory diseases, it is essential to identify and characterize the homologues of human eotaxin (C-C chemokine ligand 11) and CCR3 from other species, such as non-human primates. Accordingly, we cloned the macaque eotaxin and CCR3 genes and revealed that they were 91 and 92% identical at the amino acid level to their human homologues, respectively. Macaque CCR3 expressed in the murine pre-B L1-2 cell line bound macaque eotaxin with high affinity (K(d) = 0.1 nm) and exhibited a robust eotaxin-induced Ca(2+) flux and chemotaxis. Characterization of beta-chemokines on native macaque CCR3 on eosinophils was performed by means of eotaxin-induced shape change in whole blood using a novel signaling assay known as gated autofluorescence forward scatter. Additionally, mAbs were raised against macaque CCR3 using two different immunogens: a 30-amino acid synthetic peptide derived from the predicted NH(2) terminus of macaque CCR3 and intact macaque CCR3-transfected cells. These anti-macaque CCR3 monoclonal antibodies exhibited potent antagonist activity in receptor binding and functional assays. The characterization of the macaque eotaxin/CCR3 axis and development of antagonistic anti-macaque CCR3 monoclonal antibodies will facilitate the development of CCR3 small molecule antagonists with the hope of ameliorating chronic inflammatory diseases in humans.