Utilizing PK and PD Biomarkers to Guide the First-in-Human Starting Dose Selection of MTBT1466A: A Novel Humanized Monoclonal Anti-TGFβ3 Antibody for the Treatment of Fibrotic Diseases

MTBT1466A is a high-affinity TGFβ3-specific humanized IgG1 monoclonal antibody with reduced Fc effector function, currently under investigation in clinical trials as a potential anti-fibrotic therapy. Here, we characterized the pharmacokinetics (PK) and pharmacodynamics (PD) of MTBT1466A in mice and monkeys and predicted the PK/PD of MTBT1466A in humans to guide the selection of the first-in-human (FIH) starting dose. MTBT1466A demonstrated a typical IgG1-like biphasic PK profile in monkeys, and the predicted human clearance of 2.69 mL/day/kg and t1/2 of 20.4 days are consistent with those expected for a human IgG1 antibody. In a mouse model of bleomycin-induced lung fibrosis, changes in expression of TGFβ3-related genes, serpine1, fibronectin-1, and collagen 1A1 were used as PD biomarkers to determine the minimum pharmacologically active dose of 1 mg/kg. Unlike in the fibrosis mouse model, evidence of target engagement in healthy monkeys was only observed at higher doses. Using a PKPD-guided approach, the recommended FIH dose of 50 mg, IV, provided exposures that were shown to be safe and well tolerated in healthy volunteers. MTBT1466A PK in healthy volunteers was predicted reasonably well using a PK model with allometric scaling of PK parameters from monkey data. Taken together, this work provides insights into the PK/PD behavior of MTBT1466A in preclinical species, and supports the translatability of the preclinical data into the clinic.

Nonclinical Pharmacokinetics and Pharmacodynamics Characterization of Anti-CD79b/CD3 T Cell-Dependent Bispecific Antibody Using a Surrogate Molecule: A Potential Therapeutic Agent for B Cell Malignancies

The T cell-dependent bispecific (TDB) antibody, anti-CD79b/CD3, targets CD79b and CD3 cell-surface receptors expressed on B cells and T cells, respectively. Since the anti-CD79b arm of this TDB binds only to human CD79b, a surrogate TDB that binds to cynomolgus monkey CD79b (cyCD79b) was used for preclinical characterization. To evaluate the impact of CD3 binding affinity on the TDB pharmacokinetics (PK), we utilized non-tumor-targeting bispecific anti-gD/CD3 antibodies composed of a low/high CD3 affinity arm along with a monospecific anti-gD arm as controls in monkeys and mice. An integrated PKPD model was developed to characterize PK and pharmacodynamics (PD). This study revealed the impact of CD3 binding affinity on anti-cyCD79b/CD3 PK. The surrogate anti-cyCD79b/CD3 TDB was highly effective in killing CD79b-expressing B cells and exhibited nonlinear PK in monkeys, consistent with target-mediated clearance. A dose-dependent decrease in B cell counts in peripheral blood was observed, as expected. Modeling indicated that anti-cyCD79b/CD3 TDB’s rapid and target-mediated clearance may be attributed to faster internalization of CD79b, in addition to enhanced CD3 binding. The model yielded unbiased and precise curve fits. These findings highlight the complex interaction between TDBs and their targets and may be applicable to the development of other biotherapeutics.

Nonclinical safety assessment of a human interleukin-22FC IG fusion protein demonstrates in vitro to in vivo and cross-species translatability

Although Interleukin-22 (IL-22) is produced by various leukocytes, it preferentially targets cells with epithelial origins. IL-22 exerts essential roles in modulating various tissue epithelial functions, such as innate host defense against extracellular pathogens, barrier integrity, regeneration, and wound healing. Therefore, IL-22 is thought to have therapeutic potential in treating diseases associated with infection, tissue injury or chronic tissue damage. A number of in vitro and in vivo nonclinical studies were conducted to characterize the pharmacological activity and safety parameters of UTTR1147A, an IL-22 recombinant fusion protein that links the human cytokine IL-22 with the Fc portion of a human immunoglobulin. To assess the pharmacological activity of UTTR1147A, STAT3 activation was evaluated in primary hepatocytes isolated from human, cynomolgus monkey, minipig, rat, and mouse after incubation with UTTR1147A. UTTR1147A activated STAT3 in all species evaluated, demonstrating that all were appropriate nonclinical species for toxicology studies. The nonclinical safety profile of UTTR1147A was evaluated in rats, minipigs, and cynomolgus monkeys to establish a safe clinical starting dose for humans in Phase I trials and to support clinical intravenous, subcutaneous and/or topical administration treatment regimen. Results demonstrate the cross-species translatability of the biological response in activating the IL-22 pathway as well as the translatability of findings from in vitro to in vivo systems. UTTR1147A was well tolerated in all species tested and induced the expected pharmacologic effects of epidermal hyperplasia and a transient increase in on-target acute phase proteins. These effects were all considered to be clinically predictable, manageable, monitorable, and reversible.

Pre-clinical and translational pharmacology of a human interleukin-22 IgG fusion protein for potential treatment of infectious or inflammatory diseases

Interleukin (IL)-22 plays protective roles in infections and in inflammatory diseases that have been linked to its meditation of innate immunity via multiple mechanisms. IL-22 binds specifically to its heterodimeric receptor, which is expressed on a variety of epithelial tissues. UTTR1147A is a recombinant fusion protein that links the human cytokine IL-22 with the Fc portion of human immunoglobulin (Ig) G4. Here, we report extensive in vitro and in vivo nonclinical studies that were conducted to characterize the pharmacological activity of UTTR1147A. The in vitro activity and potency of UTTR1147A were analyzed using primary human hepatocytes and human colonic epithelial cell lines. Assessment of in vivo efficacy was performed in a mouse colitis model and by measuring relevant pharmacodynamic biomarkers, including antimicrobial peptides REG3A/β, serum amyloid protein A (SAA) and lipopolysaccharide binding protein (LBP). The pharmacokinetic and pharmacodynamic characteristics of UTTR1147A were assessed in healthy mice, rats and cynomolgus monkeys. UTTR1147A induced STAT3 activation through binding to IL-22 receptor expressed in primary human hepatocytes and human colon cell lines. In both, activation occurred in a concentration-dependent manner with similar potencies. In the mouse colitis model, murine IL-22Fc- (muIL-22Fc) treated groups at doses of 1.25 μg and above had statistically lower average histologic colitis scores compared to the control treated group. Administration of muIL-22Fc or UTTR1147A was associated with a dose-dependent induction of PD markers REG3β and SAA in rodents as well as REG3A, SAA and LBP in cynomolgus monkeys. The combined data confirm pharmacological activity of IL-22Fc and support potential regenerative and protective mechanisms in epithelial tissues.

A Preclinical Population Pharmacokinetic Model for Anti-CD20/CD3 T-Cell-Dependent Bispecific Antibodies

CD20 is a cell‐surface receptor expressed by healthy and neoplastic B cells and is a well‐established target for biologics used to treat B‐cell malignancies. Pharmacokinetic (PK) and pharmacodynamic (PD) data for the anti‐CD20/CD3 T‐cell‐dependent bispecific antibody BTCT4465A were collected in transgenic mouse and nonhuman primate (NHP) studies. Pronounced nonlinearity in drug elimination was observed in the murine studies, and time‐varying, nonlinear PK was observed in NHPs, where three empirical drug elimination terms were identified using a mixed‐effects modeling approach: i) a constant nonsaturable linear clearance term (7 mL/day/kg); ii) a rapidly decaying time‐varying, linear clearance term (t_½ = 1.6 h); and iii) a slowly decaying time‐varying, nonlinear clearance term (t_½ = 4.8 days). The two time‐varying drug elimination terms approximately track with time scales of B‐cell depletion and T‐cell migration/expansion within the central blood compartment. The mixed‐effects NHP model was scaled to human and prospective clinical simulations were generated.

Automated Affinity Capture and On-Tip Digestion to Accurately Quantitate in Vivo Deamidation of Therapeutic Antibodies

Deamidation of therapeutic antibodies may result in decreased drug activity and undesirable changes in pharmacokinetics and immunogenicity. Therefore, it is necessary to monitor the deamidation levels [during storage] and after in vivo administration. Because of the complexity of in vivo samples, immuno-affinity capture is widely used for specific enrichment of the target antibody prior to LC-MS. However, the conventional use of bead-based methods requires large sample volumes and extensive processing steps. Furthermore, with automation difficulties and extended sample preparation time, bead-based approaches may increase artificial deamidation. To overcome these challenges, we developed an automated platform to perform tip-based affinity capture of antibodies from complex matrixes with rapid digestion and peptide elution into 96-well microtiter plates followed by LC-MS analysis. Detailed analyses showed that the new method presents high repeatability and reproducibility with both intra and inter assay CVs < 8%. Using the automated platform, we successfully quantified the levels of deamidation of a humanized monoclonal antibody in cynomolgus monkeys over a time period of 12 weeks after administration. Moreover, we found that deamidation kinetics between in vivo samples and samples stressed in vitro at neutral pH were consistent, suggesting that the in vitro stress test may be used as a method to predict the liability to deamidation of therapeutic antibodies in vivo.

Effect of antigen binding affinity and effector function on the pharmacokinetics and pharmacodynamics of anti-IgE monoclonal antibodies

Modulating the binding affinities to IgE or changing the FcγR binding properties of anti-IgE antibodies offers an opportunity to enhance the therapeutic potential of anti-IgE antibodies, but the influence of increased affinity to IgE or reduced Fc effector function on the pharmacological properties of anti-IgE therapies remains unclear. Our studies were designed to characterize the pharmacokinetics, pharmacodynamics and immune-complex distribution of two high-affinity anti-IgE monoclonal antibodies, high-affinity anti-IgE antibody (HAE) 1 and 2, in mice and monkeys. HAE1, also known as PRO98498, is structurally similar to omalizumab (Xolair®), a humanized anti-IgE IgG1 marketed for the treatment of asthma, but differs by 9 amino acid changes in the complementarity-determining region resulting in a 23-fold improvement in affinity. HAE2 is similar to HAE1, but its Fc region was altered to reduce binding to Fcγ receptors. As expected given the decreased binding to Fcγ receptors, systemic exposure to pre-formed HAE2:IgE complexes in mice was greater (six-fold) and distribution to the liver lower (four-fold) compared with HAE1:IgE complexes. In monkeys, systemic exposure to HAE1 was similar to that previously observed for omalizumab in this species, but required comparatively lower serum drug concentrations to suppress free IgE levels. HAE2 treatment resulted in greater exposure and greater increase of total IgE, relative to HAE1, because of decreased clearance of HAE2:IgE complexes. Overall, these data suggest that increased binding affinity to IgE may provide a more effective therapeutic for asthma patients, and that retaining FcγR binding of the anti-IgE antibody is important for elimination of anti-IgE:IgE complexes.

A humanized monoclonal antibody targeting the β7 integrin selectively blocks intestinal homing of T lymphocytes

BACKGROUND AND PURPOSE

rhuMAb Beta7 is a humanized anti-human β7 monoclonal antibody currently in phase I in inflammatory bowel disease. rhuMAb Beta7 binds the β7 subunit of the integrins α4β7 and αEβ7, blocking interaction with their ligands. These integrins play key roles in immune cell homing to and retention in mucosal sites, and are associated with chronic inflammatory diseases of the gastrointestinal tract. The goal of this study was to evaluate the mucosal specificity of rhuMAb Beta7.

EXPERIMENTAL APPROACH

We assessed the effect of murine anti-Beta7 on lymphocyte homing in mouse models of autoimmune disease. We also compared the effect of rhuMAb Beta7 on circulating mucosal-homing versus peripheral-homing T cells in naïve non-human primates.

KEY RESULTS

In cynomolgus monkeys, occupancy of β7 integrin receptors by rhuMAb Beta7 correlated with an increase in circulating β7(+) mucosal-homing lymphocytes, with no apparent effect on levels of circulating β7(-) peripheral-homing lymphocytes. rhuMAb Beta7 also inhibited lymphocyte homing to the inflamed colons of severe combined immunodeficient mice in CD45RB(high) CD4(+) T-cell transfer models. Consistent with a lack of effect on peripheral homing, in a mouse model of experimental autoimmune encephalomyelitis, anti-β7 treatment resulted in no amelioration of CNS inflammation.

CONCLUSIONS AND IMPLICATIONS

The results presented here suggest that rhuMAb Beta7 selectively blocks lymphocyte homing to the gastrointestinal tract without affecting lymphocyte trafficking to non-mucosal tissues. rhuMAb Beta7 provides a targeted therapeutic approach with the potential for a more attractive benefit:risk ratio than currently available inflammatory bowel disease therapies.

Evidence for an asialoglycoprotein receptor on nonparenchymal cells for O-linked glycoproteins

B cell-activating factor receptor 3 (BR3)-Fc is an IgG1-receptor dimeric fusion protein that has multiple O-linked glycosylation sites and sialylation levels that can vary in the manufacturing process. Increased sialic acid levels resulted from increased site occupancy with the O-linked N-acetylgalactosamine (GalNAc-Gal), but because the ratio of sialic acid per mole of oligosaccharide remained approximately 1, this led to increased asialo terminal GalNAc. Previous studies have demonstrated an effect of terminal asialo Gal or GalNAc on the clearance of glycoproteins due to uptake and degradation by lectin receptors in the liver. However, the previous studies examined N-linked oligosaccharides, and there are less data regarding O-linked oligosaccharides. The objective of these studies was to determine the effects on the pharmacokinetics and distribution of the asialo terminal GalNAc and varying amounts of sialic acid residues on BR3-Fc. The results of the data presented here suggest that exposed Gal on the desialylated BR3-Fc led to rapid clearance due to uptake and degradation in the liver that was associated with nonparenchymal cells. It is interesting to note that the data indicated a decreased clearance and increased exposure of BR3-Fc as the sialic acid levels increased, even though increased sialic acid was associated with increased asialo GalNAc. Therefore, the exposed GalNAc did not seem to play a role in the clearance of BR3-Fc; although the Gal linked to the hydroxyl group at position 3 may have prevented an interaction. Because we did not see uptake of desialylated BR3-Fc in hepatocytes where the asialoglycoprotein receptor is localized, this nonparenchymal cell lectin may have preference for O-linked glycoproteins.

Dose schedule of recombinant murine thrombopoietin prior to myelosuppressive and myeloablative therapy in mice

PURPOSE

Thrombopoietin is being investigated as a therapeutic agent for platelet recovery following myelosuppressive therapy. Little information is available, however, on the optimal dose of this drug or the timing of its administration. To develop these data, a series of studies were conducted to examine the effects that time of dosing has on the efficacy and safety of recombinant full-length murine thrombopoietin in murine myelosuppression and murine myeloablation models.

METHODS

For the myelosuppression model, mice were exposed to 500 rad whole-body irradiation in a cesium irradiator and received an intraperitoneal dose of 1.2 mg carboplatin at time 0. For the myeloablation model, mice were exposed to 900 to 950 rad of whole-body irradiation at time 0.

RESULTS

Significant increases in the number of platelets and red and white blood cells were observed by day 10 in mice that had received a single intravenous bolus dose of recombinant murine thrombopoietin from 2 h before until 4 h after myelosuppressive therapy compared to those had received myelosuppressive therapy alone. In the myeloablation studies, mice treated with 900 rad of whole-body irradiation alone had a mortality rate of 50% compared to 0% for mice that had received recombinant murine thrombopoietin 2 h prior to whole-body irradiation. When the whole-body irradiation dose was increased to 950 rad, the mortality rate of the control mice was 83% compared to 25% for mice that had received recombinant murine thrombopoietin 2 h prior to whole-body irradiation. Dosing with recombinant murine thrombopoietin 7 days prior to whole-body irradiation resulted in a mortality rate greater than or equal to that of control mice.

CONCLUSIONS

These data suggest that pretreatment with thrombopoietin can dramatically affect recovery from myelosuppressive and myeloablative therapy. Therefore, the timing of thrombopoietin administration in relation to the therapy may be critical to the drug's safety and efficacy.