A mechanistic PK/PD model of AZD0171 (anti-LIF) to support Phase II dose selection.

AZD0171 (INN: Falbikitug) is being developed as a humanized monoclonal antibody (mAb), immunoglobulin G subclass 1 (IgG1), which binds specifically to the immunosuppressive human cytokine leukemia inhibitory factor (LIF) and inhibits downstream signaling by blocking recruitment of glycoprotein 130 (gp130) to the LIF receptor (LIFR) subunit (gp190) and the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and is intended to treat adult participants with advanced solid tumors. LIF is a pleiotropic cytokine (and a member of the IL-6 family of cytokines) involved in many physiological and pathological processes and is highly expressed in a subset of solid tumors, including non-small cell lung cancer (NSCLC), colon, ovarian, prostate, and pancreatic cancer. The aim of this work was to develop a mechanistic PK/PD model to investigate the effect of AZD0171 on tumor LIF levels, predict the level of downstream signaling complex (LIF:LIFR:gp130) inhibition, and examine the dose-response relationship to support dose selection for a Phase II clinical study. Modeling results show that tumor LIF is inhibited in a dose-dependent manner with >90% inhibition for 95% of patients at the Phase II clinical dose of 1500 mg Q2W.

Tozorakimab (MEDI3506): an anti-IL-33 antibody that inhibits IL-33 signalling via ST2 and RAGE/EGFR to reduce inflammation and epithelial dysfunction.

Interleukin (IL)-33 is a broad-acting alarmin cytokine that can drive inflammatory responses following tissue damage or infection and is a promising target for treatment of inflammatory disease. Here, we describe the identification of tozorakimab (MEDI3506), a potent, human anti-IL-33 monoclonal antibody, which can inhibit reduced IL-33 (IL-33red) and oxidized IL-33 (IL-33ox) activities through distinct serum-stimulated 2 (ST2) and receptor for advanced glycation end products/epidermal growth factor receptor (RAGE/EGFR complex) signalling pathways. We hypothesized that a therapeutic antibody would require an affinity higher than that of ST2 for IL-33, with an association rate greater than 107 M-1 s-1, to effectively neutralize IL-33 following rapid release from damaged tissue. An innovative antibody generation campaign identified tozorakimab, an antibody with a femtomolar affinity for IL-33red and a fast association rate (8.5 × 107 M-1 s-1), which was comparable to soluble ST2. Tozorakimab potently inhibited ST2-dependent inflammatory responses driven by IL-33 in primary human cells and in a murine model of lung epithelial injury. Additionally, tozorakimab prevented the oxidation of IL-33 and its activity via the RAGE/EGFR signalling pathway, thus increasing in vitro epithelial cell migration and repair. Tozorakimab is a novel therapeutic agent with a dual mechanism of action that blocks IL-33red and IL-33ox signalling, offering potential to reduce inflammation and epithelial dysfunction in human disease.

Recombinant sclerostin inhibits bone formation in vitro and in a mouse model of sclerosteosis.

BACKGROUND: Sclerosteosis, a severe autosomal recessive sclerosing skeletal dysplasia characterised by excessive bone formation, is caused by absence of sclerostin, a negative regulator of bone formation that binds LRP5/6 Wnt co-receptors. Current treatment is limited to surgical management of symptoms arising from bone overgrowth. This study investigated the effectiveness of sclerostin replacement therapy in a mouse model of sclerosteosis. METHODS: Recombinant wild type mouse sclerostin (mScl) and novel mScl fusion proteins containing a C-terminal human Fc (mScl hFc), or C-terminal human Fc with a poly-aspartate motif (mScl hFc PD), were produced and purified using mammalian expression and standard chromatography methods. In vitro functionality and efficacy of the recombinant proteins were evaluated using three independent biophysical techniques and an in vitro bone nodule formation assay. Pharmacokinetic properties of the proteins were investigated in vivo following a single administration to young female wild type (WT) or SOST knock out (SOST-/-) mice. In a six week proof-of-concept in vivo study, young female WT or SOST-/- mice were treated with 10 mg/kg mScl hFc or mScl hFc PD (weekly), or 4.4 mg/kg mScl (daily). The effect of recombinant sclerostin on femoral cortical and trabecular bone parameters were assessed by micro computed tomography (µCT). RESULTS: Recombinant mScl proteins bound to the extracellular domain of the Wnt co-receptor LRP6 with high affinity (nM range) and completely inhibited matrix mineralisation in vitro. Pharmacokinetic assessment following a single dose administered to WT or SOST-/- mice indicated the presence of hFc increased protein half-life from less than 5 min to at least 1.5 days. Treatment with mScl hFc PD over a six week period resulted in modest but significant reductions in trabecular volumetric bone mineral density (vBMD) and bone volume fraction (BV/TV), of 20% and 15%, respectively. CONCLUSION: Administration of recombinant mScl hFc PD partially corrected the high bone mass phenotype in SOST-/- mice, suggesting that bone-targeting of sclerostin engineered to improve half-life was able to negatively regulate bone formation in the SOST-/- mouse model of sclerosteosis. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: These findings support the concept that exogenous sclerostin can reduce bone mass, however the modest efficacy suggests that sclerostin replacement may not be an optimal strategy to mitigate excessive bone formation in sclerosteosis, hence alternative approaches should be explored.

Efficacy and Safety of MEDI2070, an Antibody Against Interleukin 23, in Patients With Moderate to Severe Crohn's Disease: A Phase 2a Study.

BACKGROUND & AIMS: MEDI2070 is a human monoclonal antibody that selectively inhibits interleukin 23 (IL23), a cytokine implicated in the pathogenesis of Crohn's disease (CD). We analyzed its safety and efficacy in treatment of CD in a phase 2a study. METHODS: We conducted a double-blind, placebo-controlled study of 119 adults with moderate to severe CD failed by treatment with tumor necrosis factor antagonists. Patients were randomly assigned (1:1) to groups given MEDI2070 (700 mg) or placebo intravenously at weeks 0 and 4. Patients received open-label MEDI2070 (210 mg) subcutaneously every 4 weeks from weeks 12 to 112. The CD Activity Index was used to measure disease activity. RESULTS: The primary outcome, clinical response (either a 100-point decrease in CD Activity Index score from baseline or clinical remission, defined as CD Activity Index score <150) at week 8 occurred in 49.2% of patients receiving MEDI2070 (n = 59) compared with 26.7% receiving placebo (n = 60; absolute difference, 22.5%; 95% confidence interval, 5.6%-39.5%; P = .010). Clinical response at week 24 occurred in 53.8% of patients who continued to receive open-label MEDI2070 and in 57.7% of patients who had received placebo during the double-blind period and open-label MEDI2070 thereafter. The most common adverse events were headache and nasopharyngitis. Higher baseline serum concentrations of IL22, a cytokine whose expression is induced by IL23, were associated with greater likelihood of response to MEDI2070 compared with placebo. CONCLUSIONS: In a phase 2a trial of patients with moderate to severe Crohn's disease who had failed treatment with tumor necrosis factor antagonists, 8 and 24 weeks of treatment with MEDI2070 were associated with clinical improvement. ClinicalTrials.gov ID: NCT01714726.

Structural and functional characterization of a specific antidote for ticagrelor.

Ticagrelor is a direct-acting reversibly binding P2Y12 antagonist and is widely used as an antiplatelet therapy for the prevention of cardiovascular events in acute coronary syndrome patients. However, antiplatelet therapy can be associated with an increased risk of bleeding. Here, we present data on the identification and the in vitro and in vivo pharmacology of an antigen-binding fragment (Fab) antidote for ticagrelor. The Fab has a 20 pM affinity for ticagrelor, which is 100 times stronger than ticagrelor's affinity for its target, P2Y12. Despite ticagrelor's structural similarities to adenosine, the Fab is highly specific and does not bind to adenosine, adenosine triphosphate, adenosine 5'-diphosphate, or structurally related drugs. The antidote concentration-dependently neutralized the free fraction of ticagrelor and reversed its antiplatelet activity both in vitro in human platelet-rich plasma and in vivo in mice. Lastly, the antidote proved effective in normalizing ticagrelor-dependent bleeding in a mouse model of acute surgery. This specific antidote for ticagrelor may prove valuable as an agent for patients who require emergency procedures.

Evaluation of molecular markers in low-grade diffuse astrocytomas: loss of p16 and retinoblastoma protein expression is associated with short survival.

Diffuse astrocytomas have a median survival of 6-8 years. However, in a minority of cases that are histologically low grade, progression is rapid, leading to death within 2 years. Loss of p16, retinoblastoma protein, and deleted-in-colon-carcinoma protein expression, and monosomy of chromosome 10 have been shown to occur in malignant astrocytic tumors. We have investigated the prognostic value of expression of these markers, using techniques applicable in many histopathology laboratories, in diffuse astrocytomas that are histologically low grade. Paraffin sections from 71 diffuse, supratentorial, low-grade astrocytomas, from patients with at least 8-year survival data, were immunostained with antibodies to p16, deleted-in-colon-carcinoma protein, p53, Ki67, and retinoblastoma protein. In situ hybridization with a digoxigenin-labeled probe to chromosome 10 was used to assess chromosomal loss. In most cases there was immunostaining of virtually all tumor cell nuclei with antibodies to p16 and retinoblastoma protein. Three of the 68 tumors in which assessment of p16 was possible included discrete foci with lack of detectable immunoreactivity in tumor cells. The three patients concerned had a significantly shortened median survival (1.1 years vs 4.4 years in those without loss of p16; p <0.01). In six of the 61 cases where assessment of retinoblastoma protein was possible, <70% of tumor cell nuclei showed immunoreactivity. These six patients had a shorter survival (4.0 years) than had the remaining patients (5.4 years), although this difference was not statistically significant. The tumor from one of these patients included areas where only 36% of tumor cells showed retinoblastoma protein immunoreactivity, and this patient survived only 1.5 years. Tumors showing loss of both p16 and retinoblastoma were not seen. p53 and deleted-in-colon-carcinoma protein expression was highly variable and did not correlate with survival. Tumors with monosomy for chromosome 10 were not identified. Both polyploidy and the Ki67 labeling index were significantly associated with the p53 labeling index but not with survival. Focal loss of p16 or retinoblastoma protein is demonstrable in approximately 5% and 10% of diffuse low-grade diffuse astrocytomas, respectively. Tumors with focal loss of immunoreactivity for these proteins are associated with shorter survival than those without, suggesting that immunohistochemistry for p16 and retinoblastoma protein may be a useful adjunct to other methods for assessing the prognosis of astrocytomas.