Discovery of TRPA1 Antagonist GDC-6599: Derisking Preclinical Toxicity and Aldehyde Oxidase Metabolism with a Potential First-in-Class Therapy for Respiratory Disease.

Transient receptor potential ankyrin 1 (TRPA1) is a nonselective calcium ion channel highly expressed in the primary sensory neurons, functioning as a polymodal sensor for exogenous and endogenous stimuli, and has been implicated in neuropathic pain and respiratory disease. Herein, we describe the optimization of potent, selective, and orally bioavailable TRPA1 small molecule antagonists with strong in vivo target engagement in rodent models. Several lead molecules in preclinical single- and short-term repeat-dose toxicity studies exhibited profound prolongation of coagulation parameters. Based on a thorough investigative toxicology and clinical pathology analysis, anticoagulation effects in vivo are hypothesized to be manifested by a metabolite─generated by aldehyde oxidase (AO)─possessing a similar pharmacophore to known anticoagulants (i.e., coumarins, indandiones). Further optimization to block AO-mediated metabolism yielded compounds that ameliorated coagulation effects in vivo, resulting in the discovery and advancement of clinical candidate GDC-6599, currently in Phase II clinical trials for respiratory indications.

Intravitreal RTH258 (brolucizumab) demonstrates no effect on pregnancy, parturition, embryofetal or postnatal development in cynomolgus monkeys.

RTH258 (brolucizumab) is a humanized single chain antibody fragment, the smallest functional unit of an antibody designed to target vascular endothelial growth factor in angiogenic retinal disease. To further understand the safe use of RTH258, this study assessed the potential impact of intravitreal RTH258 on pre- and postnatal development in the offspring of cynomolgus monkeys following administration to the mother. Three groups of 16 pregnant females were included: a low dose group (RTH258 3 mg/50 µl [60 mg/ml]), a high dose group (RTH258 6 mg/50 µl [120 mg/ml]), and a control group. Maternal animals were administered a single injection of 50 µl in the right eye once every four weeks. Animals were observed daily and detailed observations were collected before and after the first dose, and then weekly thereafter. Following parturition, observations of infants included external, morphological, and ophthalmic examinations; neurobehavioral test battery; grip strength; and skeletal development. Blood samples for hematology, coagulation, and clinical chemistry were collected from non-fasted maternal and infant animals. No RTH258-related deaths occurred in maternal dams or infants. No RTH258-related clinical observations were noted in maternal animals or in surviving infants - there were no changes in gestation length; pregnancy loss; deaths; body weight/weight change; infant grip strength; infant external, morphological, or skeletal evaluations; ophthalmoscopy or neurobehavioral observations; or clinical pathology parameters. RTH258 had no impact on pregnancy or parturition; embryo-fetal development; or survival, growth, or postnatal development of offspring when administered via repeated intravitreal administration.

CSL-Tox: an open-source analytical framework for the comparison of short-term and long-term toxicity end points and assessing the need of chronic studies in drug development.

In-vivo toxicity assessment is an important step prior to clinical development and is still the main source of data for overall risk assessment of a new molecular entity (NCE). All in-vivo studies are performed according to regulatory requirements and many efforts have been exerted to minimize these studies in accordance with the (Replacement, Reduction and Refinement) 3Rs principle. Many aspects of in-vivo toxicology packages can be optimized to reduce animal use, including the number of studies performed as well as study durations, which is the main focus of this analysis. We performed a statistical comparison of adverse findings observed in 116 short-term versus 78 long-term in-house or in-house sponsored Contract Research Organizations (CRO) studies, in order to explore the possibility of using only short-term studies as a prediction tool for the longer-term effects. All the data analyzed in this study was manually extracted from the toxicology reports (in PDF formats) to construct the dataset. Annotation of treatment related findings was one of the challenges faced during this work. A specific focus was therefore put on the summary and conclusion sections of the reports since they contain expert assessments on whether the findings were considered adverse or were attributed to other reasons. Our analysis showed a general good concordance between short-term and long-term toxicity findings for large molecules and the majority of small molecules. Less concordance was seen for certain body organs, which can be named as "target organ systems' findings". While this work supports the minimization of long-term studies, a larger-scale effort would be needed to provide more evidence. We therefore present the steps performed in this study as an open-source R workflow for the Comparison of Short-term and Long-term Toxicity studies (CSL-Tox). The dataset used in the work is provided to allow researchers to reproduce such analysis, re-evaluate the statistical tools used and promote large-scale application of this study. Important aspects of animal research reproducibility are highlighted in this work, specifically, the necessity of a reproducible adverse effects reporting system and utilization of the controlled terminologies in-vivo toxicology reports and finally the importance of open-source analytical workflows that can be assessed by other scientists in the field of preclinical toxicology.

International consortium for innovation and quality: An industry perspective on the nonclinical and early clinical development of intravitreal drugs.

The eye, which is under constant exposure to environmental pathogens, has evolved various anatomic and immunological barriers critical to the protection of tissues lacking regenerative capacity, and the maintenance of a clear optic pathway essential to vision. By bypassing the ocular barriers, intravitreal (IVT) injection has become the mainstay for the delivery of drugs to treat conditions that affect the back of the eye. Both small molecules and biotherapeutics have been successfully administered intravitreally, and several drugs have been approved for the treatment of (wet) age-related macular degeneration and diabetic macular edema. However, IVT injection is an invasive procedure, which requires sufficient technical expertise from the healthcare professional administering the drug. Potential side effects include bleeding, retinal tear, cataracts, infection, uveitis, loss of vision, and increased ocular pressure. Pharmaceutical companies often differ in their drug development plan, including drug administration techniques, collection of ocular tissues and fluids, ophthalmology monitoring, and overall conduct of nonclinical and clinical studies. The present effort, under the aegis of the Innovation & Quality Ophthalmic Working Group, aims at understanding these differences, identifying pros and cons of the various approaches, determining the gaps in knowledge, and suggesting feasible good practices for nonclinical and early clinical IVT drug development.

Scientific and Regulatory Policy Committee Points to Consider: Fixation, Trimming, and Sectioning of Nonrodent Eyes and Ocular Tissues for Examination in Ocular and General Toxicity Studies.

A Working Group of the Society of Toxicologic Pathology's Scientific and Regulatory Policy Committee conducted a technical and scientific review of current practices relating to the fixation, trimming, and sectioning of the nonrodent eye to identify key points and species-specific anatomical landmarks to consider when preparing and evaluating eyes of rabbits, dogs, minipigs, and nonhuman primates from ocular and general toxicity studies. The topics addressed in this Points to Consider article include determination of situations when more comprehensive evaluation of the globe and/or associated extraocular tissues should be implemented (expanded ocular sampling), and what constitutes expanded ocular sampling. In addition, this manuscript highlights the practical aspects of fixing, trimming, and sectioning the eye to ensure adequate histopathological evaluation of all major ocular structures, including the cone-dense areas (visual streak/macula/fovea) of the retina for rabbits, dogs, minipigs, and nonhuman primates, which is a current regulatory expectation for ocular toxicity studies.[Box: see text].

Uncovering of intraspecies macular heterogeneity in cynomolgus monkeys using hybrid machine learning optical coherence tomography image segmentation.

The fovea is a depression in the center of the macula and is the site of the highest visual acuity. Optical coherence tomography (OCT) has contributed considerably in elucidating the pathologic changes in the fovea and is now being considered as an accompanying imaging method in drug development, such as antivascular endothelial growth factor and its safety profiling. Because animal numbers are limited in preclinical studies and automatized image evaluation tools have not yet been routinely employed, essential reference data describing the morphologic variations in macular thickness in laboratory cynomolgus monkeys are sparse to nonexistent. A hybrid machine learning algorithm was applied for automated OCT image processing and measurements of central retina thickness and surface area values. Morphological variations and the effects of sex and geographical origin were determined. Based on our findings, the fovea parameters are specific to the geographic origin. Despite morphological similarities among cynomolgus monkeys, considerable variations in the foveolar contour, even within the same species but from different geographic origins, were found. The results of the reference database show that not only the entire retinal thickness, but also the macular subfields, should be considered when designing preclinical studies and in the interpretation of foveal data.

Antibody semorinemab reduces tau pathology in a transgenic mouse model and engages tau in patients with Alzheimer's disease.

Tau has become an attractive alternative target for passive immunotherapy efforts for Alzheimer's disease (AD). The anatomical distribution and extent of tau pathology correlate with disease course and severity better than other disease markers to date. We describe here the generation, preclinical characterization, and phase 1 clinical characterization of semorinemab, a humanized anti-tau monoclonal antibody with an immunoglobulin G4 (igG4) isotype backbone. Semorinemab binds all six human tau isoforms and protects neurons against tau oligomer neurotoxicity in cocultures of neurons and microglia. In addition, when administered intraperitoneally once weekly for 13 weeks, murine versions of semorinemab reduced the accumulation of tau pathology in a transgenic mouse model of tauopathy, independent of antibody effector function status. Semorinemab also showed clear evidence of target engagement in vivo, with increases in systemic tau concentrations observed in tau transgenic mice, nonhuman primates, and humans. Higher concentrations of systemic tau were observed after dosing in AD participants compared to healthy control participants. No concerning safety signals were observed in the phase 1 clinical trial at single doses up to 16,800 mg and multiple doses totaling 33,600 mg in a month.

Inflammation of a Posterior Ciliary Artery in a Naive Cynomolgus Macaque.

This brief communication describes a previously unreported background lesion in the eye of a naive cynomolgus macaque. Inflammation of a posterior ciliary artery was, in this case, morphologically similar to vascular inflammation of other tissues described in naive cynomolgus macaques. However, the available literature does not describe this lesion at this anatomical site. The affected animal did not present with any abnormal clinical signs and ophthalmological examinations were within normal limits. Toxicologic pathologists should be aware of this finding in order to help differentiate it from a test item-related finding.

Intravitreal Administration of Acetyl Triethyl Citrate and Benzyl Benzoate Is Retinotoxic in Rabbits but Not in Cynomolgus Monkeys.

Sustained drug delivery formulations are developed to reduce dose frequency while maintaining efficacy of intravitreal (ITV) administered therapeutics. Available safety data for components novel to the eye's posterior segment may be limited, requiring preclinical assessments to identify potential toxicities. We evaluated the in vivo and in vitro safety of two solvents, acetyl triethyl citrate (ATEC) and benzyl benzoate (BB), as novel sustained delivery formulations for ITV administration. In vivo tolerability was assessed following ITV administration of ATEC and BB to rabbits and cynomolgus monkeys. In rabbits, ITV solvent administration resulted in moderate to severe retinal toxicity characterized by focal retinal necrosis and/or degeneration, sometimes accompanied by inflammation, with a clear association between the physical presence of the solvent and areas of retinal damage. In contrast, solvent administration in monkeys appeared well tolerated, producing no histologic abnormalities. Toxicity in primary human retinal pigment epithelial cells, characterized by cellular toxicity and mitochondrial injury, corroborated the retinal toxicity in rabbits. In conclusion, ITV solvent depots of ATEC or BB result in chemical and focal retinal toxicity in rabbits, but not monkeys. Additional investigation is needed to demonstrate a sufficient margin of safety prior to use of ATEC or BB in ITV drug products.

An Anti-CD22-seco-CBI-Dimer Antibody-Drug Conjugate (ADC) for the Treatment of Non-Hodgkin Lymphoma That Provides a Longer Duration of Response than Auristatin-Based ADCs in Preclinical Models.

We are interested in developing a second generation of antibody-drug conjugates (ADCs) for the treatment of non-Hodgkin lymphoma (NHL) that could provide a longer duration of response and be more effective in indolent NHL than the microtubule-inhibiting ADCs pinatuzumab vedotin [anti-CD22-vc-monomethyl auristatin E (MMAE)] and polatuzumab vedotin (anti-CD79b-vc-MMAE). Pinatuzumab vedotin (anti-CD22-vc-MMAE) and polatuzumab vedotin (anti-CD79b-vc-MMAE) are ADCs that contain the microtubule inhibitor MMAE. Clinical trial data suggest that these ADCs have promising efficacy for the treatment of NHL; however, some patients do not respond or become resistant to the ADCs. We tested an anti-CD22 ADC with a seco-CBI-dimer payload, thio-Hu anti-CD22-(LC:K149C)-SN36248, and compared it with pinatuzumab vedotin for its efficacy and duration of response in xenograft models and its ability to deplete normal B cells in cynomolgus monkeys. We found that anti-CD22-(LC:K149C)-SN36248 was effective in xenograft models resistant to pinatuzumab vedotin, gave a longer duration of response, had a different mechanism of resistance, and was able to deplete normal B cells better than pinatuzumab vedotin. These studies provide evidence that anti-CD22-(LC:K149C)-SN36248 has the potential for longer duration of response and more efficacy in indolent NHL than MMAE ADCs and may provide the opportunity to improve outcomes for patients with NHL.

Nonclinical Safety Assessment of FHTR2163, An Antigen-Binding Fragment Against HTRA1 for the Treatment of Geographic Atrophy.

FHTR2163 is an antigen-binding fragment of a humanized immunoglobulin G1 monoclonal antibody directed against high-temperature requirement A serine peptidase 1 (HTRA1) that is being developed as a potential intravitreal (ITV) treatment for patients with geographic atrophy (GA), an advanced form of dry age-related macular degeneration. The nonclinical toxicology program was designed to assess the safety and tolerability of HTRA1 inhibition following ITV administration of FHTR2163 to support ITV administration in patients with GA. FHTR2163 was well tolerated in a single-dose ITV-administered 8-day toxicity study in cynomolgus monkeys following a 50 µL high (>700 mOsm/kg) osmolality formulation up to 12.5 mg/eye; however, 100 µL (2× 50 µL injections) of a high-osmolality formulation resulted in transient retinal detachment. Repeat-dose ITV administration every 2 weeks of FHTR2163 was well tolerated in 8- and 26-week studies with ITV injection of 100 µL (2× 50 µL) of iso-osmolar formulation up to 15 mg/eye, or 50 µL of the high-osmolality formulation up to 12.5 mg/eye. Observed transient and reversible ocular effects included inflammation and perivascular infiltrates, consistent with an immune response attributed to the administration of heterologous (humanized) protein. Overall, FHTR2163 was well tolerated, and the nonclinical package supported the continued clinical development of FHTR2163 in patients with GA.

Nonclinical Toxicology and Biocompatibility Program Supporting Clinical Development and Registration of the Port Delivery System With Ranibizumab for Neovascular Age-Related Macular Degeneration.

The Port Delivery System with ranibizumab (PDS) is an investigational drug delivery system designed to provide continuous intravitreal release of ranibizumab for extended durations. The PDS consists of a permanent, surgically placed, refillable intraocular implant; a customized formulation of ranibizumab; and ancillary devices to support surgery and refill procedures. A toxicology program was conducted to evaluate the ocular toxicology and biocompatibility of the PDS to support its clinical development program and product registrational activities. PDS safety studies included a 6-month chronic toxicology evaluation in minipigs as well as evaluation of nonfunctional surrogate implants (comprised of the same implant materials but without ranibizumab) in rabbits. Biocompatibility of the implant and ancillary devices was evaluated in both in vitro and in vivo studies. Implants and extracts from implants and ancillary devices were nongenotoxic, noncytotoxic, nonsensitizing, and nonirritating. Ocular findings were comparable between implanted and sham-operated eyes, and no systemic toxicity was observed. The results of this nonclinical toxicology program demonstrated that the PDS was biocompatible and that intravitreal delivery of ranibizumab via the PDS did not introduce any new toxicology-related safety concerns relative to intravitreal injections, supporting ongoing PDS clinical development and product registrational evaluation.

Foreign Body Reaction, Retinal Degeneration, and Epiretinal Membranes Associated With Intravitreal Administration of PLGA Rods.

Long-acting delivery platforms for intravitreal therapies are an active area of research in ophthalmic drug development. The aim of these platforms is to decrease the burden of intravitreal therapies for patients, by increasing the period between intravitreal injections. This brief communication describes the in-life, histologic and immunohistochemical findings associated with repeat-dose intravitreal administration of poly D, L sustained lactide-co-glycolide polymeric rods, an intravitreal depot, in the cynomolgus monkey (Macaca fascicularis). These nonclinical investigations illustrate a pattern of foreign body reaction around intravitreal depots at the temporal pars plana and demonstrated the histopathologic and immunohistologic features of retinal degeneration and epiretinal membrane formation in the inferior retina.

Opportunities for use of one species for longer-term toxicology testing during drug development: A cross-industry evaluation.

An international expert working group representing 37 organisations (pharmaceutical/biotechnology companies, contract research organisations, academic institutions and regulatory bodies) collaborated in a data sharing exercise to evaluate the utility of two species within regulatory general toxicology studies. Anonymised data on 172 drug candidates (92 small molecules, 46 monoclonal antibodies, 15 recombinant proteins, 13 synthetic peptides and 6 antibody-drug conjugates) were submitted by 18 organisations. The use of one or two species across molecule types, the frequency for reduction to a single species within the package of general toxicology studies, and a comparison of target organ toxicities identified in each species in both short and longer-term studies were determined. Reduction to a single species for longer-term toxicity studies, as used for the development of biologicals (ICHS6(R1) guideline) was only applied for 8/133 drug candidates, but might have been possible for more, regardless of drug modality, as similar target organ toxicity profiles were identified in the short-term studies. However, definition and harmonisation around the criteria for similarity of toxicity profiles is needed to enable wider consideration of these principles. Analysis of a more robust dataset would be required to provide clear, evidence-based recommendations for expansion of these principles to small molecules or other modalities where two species toxicity testing is currently recommended.

Retinal Features in Cynomolgus Macaques (Macaca fascicularis) Assessed by Using Scanning Laser Ophthalmoscopy and Spectral Domain Optical Coherence Tomography.

Cynomolgus macaques are an important and commonly used species in preclinical toxicology studies, but structural reports of in vivo retinal findings are rare in this species. The purpose of this study was to diminish this gap and document optical coherence tomography and scanning laser ophthalmoscopy imaging data in the healthy posterior pole of cynomolgus monkeys' eyes at predose examinations. The current study is a retrospective assessment of baseline spectral domain OCT data obtained from the 768 eyes of 384 cynomolgus monkeys (192 males and 192 females) of Mauritian origin. The data set was obtained from studies conducted over a 4-y period in the context of ocular safety evaluations of various compounds under preclinical development. The most prevalent findings were the presence of Bergmeister papilla and intravitreal hyperreflective spots. Less common findings included disorganization of retinal zones, abnormalities of the retinal vasculature, partial posterior vitreous detachment, and abnormally shaped foveal pits. Thoughtful consideration of these physiologic findings will aid in distinguishing normal features from toxic outcomes in future preclinical ophthalmic studies.

EVALUATION OF SURGICAL FACTORS AFFECTING VITREOUS HEMORRHAGE FOLLOWING PORT DELIVERY SYSTEM WITH RANIBIZUMAB IMPLANT INSERTION IN A MINIPIG MODEL.

PURPOSE: To develop an animal model of vitreous hemorrhage (VH) to explore the impact of surgical parameters on VH associated with insertion of the Port Delivery System with ranibizumab (PDS) implant. METHODS: Ninety eyes from 45 treatment-naive male Yucatan minipigs received PDS implant insertion or a sham procedure. The effect of prophylactic pars plana hemostasis, scleral incision length, scleral cauterization, surgical blade type/size, and viscoelastic usage on postsurgical VH was investigated. RESULTS: Postsurgical VH was detected in 60.0% (54/90) of implanted eyes. A systematic effect on VH was only detected for pars plana hemostasis before the pars plana incision. The percentage of eyes with VH was 96.6% (28/29) among eyes that did not receive prophylactic pars plana hemostasis and 42.4% (24/58) among eyes that did. There was no VH in eyes that received laser ablation of the pars plana using overlapping 1,000-ms spots; pars plana cautery or diathermy was less effective. The majority of all VH cases (83.3% [45/54]) were of mild to moderate severity (involving ≤25% of the fundus). CONCLUSION: In this minipig surgical model of VH, scleral dissection followed by pars plana laser ablation before pars plana incision most effectively mitigated VH secondary to PDS implant insertion.

Rapid Development of Glaucoma Via ITV Nonselective ANGPT 1/2 Antibody: A Potential Role for ANGPT/TIE2 Signaling in Primate Aqueous Humor Outflow.

Purpose: Investigate a significant, dose-related increase in IOP, leading to glaucomatous damage to the neuroretina and optic nerve following intravitreal (ITV) administration of a bispecific F(ab')2 [anti-VEGF/Angiopoietins [ANGPT]F(ab')2] molecule in adult monkeys. Methods: ITV ocular tolerability and investigation of anti-VEGF/ANGPT F(ab')2 (blocking both ANGPT1 and ANGPT2) was done in monkeys; mechanistic studies were done in neonatal mice. Results: Following the second ITV dose of anti-VEGF/ANGPT F(ab')2, all 1.5- and 4-mg/eye treated monkeys developed elevated IOP, which eventually was associated with optic disc cupping and thinning of the neuroretinal rim. Histopathologic examination showed nonreversible axonal degeneration in the optic nerves of animals administered 1.5 mg/eye and higher that was considered secondary to high IOP. Anti-ANGPT Fab also caused elevated IOP in monkeys, but anti-VEGF Fab did not contribute to the IOP increase. In addition, an anti-ANGPT2-selective antibody did not change IOP. In mice simultaneous blockade of ANGPT1 and ANGPT2 impaired the expansion and formation of Schlemm's canal (SC) vessels, similar to genetic ablation of Angpt1/Angpt2 and their receptor TIE2. As previously reported, blocking ANGPT2 alone did not affect SC formation in mice. Conclusions: Dual inhibition of ANGPT1/ANGPT2, but not ANGPT2 alone, leads to increased IOP and glaucomatous damage in monkeys. This confirms a role for TIE2/ANGPT signaling in the control of IOP in adults, a finding initially identified in transgenic mice. Dual pharmacologic inhibition of ANGPT1/ANGPT2 may affect aqueous drainage and homeostasis in adult monkeys and may be useful in developing novel models of glaucoma.

Identification and characterization of an octameric PEG-protein conjugate system for intravitreal long-acting delivery to the back of the eye.

Innovative protein engineering and chemical conjugation technologies have yielded an impressive number of drug candidates in clinical development including >80 antibody drug conjugates, >60 bispecific antibodies, >35 Fc-fusion proteins and >10 immuno-cytokines. Despite these innovations, technological advances are needed to address unmet medical needs with new pharmacological mechanisms. Age-related eye diseases are among the most common causes of blindness and poor vision in the world. Many such diseases affect the back of the eye, where the inaccessibility of the site of action necessitates therapeutic delivery via intravitreal (IVT) injection. Treatments administered via this route typically have vitreal half-lives <10 days in humans, requiring frequent administration. Since IVT injection is burdensome to patients, there exists a strong need to develop therapeutics with prolonged residence time in the eye. We report here a strategy to increase retention of a therapeutic fragment antibody (Fab) in the eye, using an anti-complement factor D Fab previously optimized for ocular delivery. Polyethylene glycol structures, varying in length, geometry and degree of branching, were coupled to the Fab via maleimide-activated termini. A screening strategy was developed to allow for key determinants of ocular half-life to be measured in vitro. After compound selection, a scalable process was established to enable tolerability and pharmacokinetic studies in cynomolgus monkeys, demonstrating an increase in vitreal half-life with no associated adverse events. Further, we show that the technique for compound selection, analytical characterization, and scalable production is general for a range of antibody fragments. The application of the technology has broad impact in across many therapeutic areas with the first major advancement in the treatment of an important ocular disease.

Determination of a No Observable Effect Level for Endotoxin Following a Single Intravitreal Administration to Cynomolgus Monkeys.

Purpose: To characterize the inflammatory response and determine the no-observable-effect level (NOEL) in cynomolgus monkey eyes after intravitreal (ITV) injection of endotoxin. Methods: The inflammatory response to endotoxin was assessed in a single-dose study in monkeys at doses of 0.01 to 0.51 endotoxin units (EU)/eye. Tolerability was assessed by clinical ophthalmic examinations, intraocular pressure measurements, fundus color photography, optical coherence tomography, and anatomic pathology. Results: ITV injection of endotoxin at ≥0.04 EU/eye resulted in a dose-related anterior segment inflammatory response. No aqueous flare or cell was noted in the 0.01 EU/eye dose group. A more delayed posterior segment response characterized by vitreous cell was observed beginning on day 5, peaking on day 15, and decreasing in some groups. Microscopic findings of mononuclear cell infiltrates in the vitreous were observed in eyes given ≥0.21 EU/eye. Conclusion: The NOEL for ITV endotoxin in cynomolgus monkeys was 0.01 EU/eye, suggesting that this species is as sensitive as rabbits to the effects of endotoxin. The vitreous cavity also appears more sensitive to endotoxin than the anterior segment/aqueous chamber. Overall, the magnitude of the inflammatory response at ≥0.04 EU/eye suggests that dose-response curve in monkeys is steeper than in rabbits. These data highlight the importance of assessing endotoxin level in ITV formulations, as levels as low as 0.04 EU/eye may confound the safety evaluations of ITV therapeutics in cynomolgus monkeys.

Nonclinical Safety Assessment of Anti-Factor D: Key Strategies and Challenges for the Nonclinical Development of Intravitreal Biologics.

PURPOSE: The nonclinical toxicology program described here was designed to characterize the safety profile of anti-factor D (AFD; FCFD4514S, lampalizumab) to support intravitreal (ITV) administration in patients with geographic atrophy (GA). METHODS: The toxicity of AFD was assessed in a single-dose and 6-month repeat-dose study in monkeys at doses up to 10 mg/eye. Toxicity was assessed by clinical ophthalmic examinations, intraocular pressure measurements, ocular photography, electroretinography, fluorescein angiography, optical coherence tomography, and anatomic pathology. RESULTS: Systemic exposure to AFD generally increased with the increase in dose level. The increases in mean maximal concentration and area under the curve values were roughly dose proportional. No accumulation of AFD was observed following 10 doses, and drug exposures were not affected by anti-drug antibodies. AFD was locally and systemically well tolerated in monkeys following ITV doses of up to 10 mg/eye. Ocular effects associated with AFD were limited to transient, reversible, dose-related, aqueous cell responses and injection-related, mild, vitreal cell responses. In the 6-month repeat-dose study, 2 monkeys had a nonspecific immune response to AFD that resulted in severe ocular inflammation, attributed to administration of a heterologous (humanized) protein. CONCLUSIONS: The comprehensive toxicology program in monkeys described here was designed to evaluate the safety profile of AFD and to support multiple ITV injections in the clinic. Administration of a heterologous (humanized) protein presents a challenge, and immunogenicity in nonclinical species is not predictive of immunogenicity in humans. Taken together, the results of the nonclinical program described here support the use of AFD in patients with GA.