Detailed characterization of the biological activities of recombinant human nerve growth factor expressed in Chinese hamster ovary cells

Safety, Tolerability, Pharmacokinetics, and Immunogenicity of a Novel Recombination Human Nerve Growth Factor in Healthy Chinese Subjects

BACKGROUND

Nerve growth factor (NGF), the first-discovered member of the neurotrophin family, has long been regarded as a potential drug to combat acute and chronic neurodegenerative processes. However, the pharmacokinetic profile of NGF is poorly described.

OBJECTIVES

The aim of this study was to investigate the safety, tolerability, pharmacokinetics, and immunogenicity of a novel recombinant human NGF (rhNGF) in healthy Chinese subjects.

METHOD

The study randomized 48 and 36 subjects to receive (i) single-ascending dose (SAD group; 7.5, 15, 30, 45, 60, 75 μg or placebo) and (ii) multiple-ascending dose (MAD group; 15, 30, 45 μg, or placebo) rhNGF intramuscular injections, respectively. In the SAD group, all participants received rhNGF or placebo only once. In the MAD group, participants were randomly assigned to receive multiple doses of rhNGF or placebo once a day for 7 consecutive days. Adverse events (AEs) and anti-drug antibodies (ADAs) were monitored throughout the study. Recombinant human NGF serum concentrations were determined using a highly sensitive enzyme-linked immunosorbent assay.

RESULTS

All AEs were mild, except for some injection-site pain and fibromyalgia, which were experienced as moderate AEs. Only one moderate AE was observed in the 15 μg cohort throughout the study and resolved within 24 hours of stopping dosing. Many participants (10% in 30 μg, 50% in 45 μg, and 50% in 60 μg in the SAD group; 10% in 15 μg, 30% in 30 μg, and 30% in 45 μg in the MAD group) experienced moderate fibromyalgia. However, all moderate fibromyalgia were resolved by the end of the subject's participation in the study. No severe AEs or clinically significant abnormalities were reported. All subjects in the 75 μg cohort experienced positive ADA in the SAD group, and one subject in the 30 μg dose and four subjects in the 45 μg dose also experienced positive ADA in the MAD group. Recombinant human nerve growth factor was absorbed (median T_max, 4.0-5.3 h) and eliminated biexponentially (mean t_1/2, 4.53-6.09 h) with a moderate speed. The C_max and AUC increased in an approximately dose-proportional manner over the dose range of 7.5-45 μg, and at doses higher than 45 μg these parameters increased more than dose proportionally. There was no obvious accumulation after 7 days of daily dosing of rhNGF.

CONCLUSION

The favorable safety and tolerability and predictable pharmacokinetic profile of rhNGF in healthy Chinese subjects support its continuing clinical development for the treatment of nerve injury and neurodegenerative diseases. The AEs and immunogenicity of rhNGF will continue to be monitored in future clinical trials.

TRIAL REGISTRATION

This study was registered with Chinadrugtrials.org.cn (ChiCTR2100042094) on January 13th, 2021.

Regulation of follicle growth and apoptosis in cultured mouse ovaries by NGF and oxygen

Cryopreservation of ovarian tissue has been proposed for use in preserving female fertility before anticancer chemo-radiotherapy, because ovarian tissue contains a large pool of non-growing, primordial follicles. The mechanisms that regulate the exit of follicles from the pool are poorly understood. To determine optimal conditions for in vitro ovarian culture, we investigated the effects of nerve growth factor (NGF) and oxygen concentration on follicle growth and apoptosis. Oxygen concentration affected both cell proliferation and apoptosis. Under 20% oxygen, but not 1.5% or 5%, NGF decreased apoptosis in mouse ovaries by down-regulating the pro-apoptotic genes Bax and p53. In conclusion, high oxygen tension during in vitro ovarian culture promotes follicle growth and, in conjunction with NGF, suppresses apoptosis. The efficiency of this method to preserve fertility depends in part on the level of atresia. These results suggest that oxygen and NGF may be used to increase numbers of preantral follicles and mature oocytes in the culture of mammalian ovarian cortical strips.

TAK-147, an acetylcholinesterase inhibitor, increases choline acetyltransferase activity in cultured rat septal cholinergic neurons

TAK-147, a potent acetylcholinesterase (AChE) inhibitor, potentiated choline acetyltransferase (ChAT) activity in cultured rat septal cholinergic neurons in a concentration-dependent manner with an EC50 value of 4.47 nM. Donepezil, another potent AChE inhibitor, also increased ChAT activity although its potency was less than that of TAK-147. Other AChE inhibitors (rivastigmine, tacrine, physostigmine and neostigmine) showed no effect. The effects of TAK-147 were greater in the presence of NGF, suggesting a synergistic action of TAK-147 and NGF. TAK-147 and donepezil showed high affinity for sigma receptors, whereas tacrine and physostigmine did not. Haloperidol and ifenprodil, high-affinity sigma ligands, potently enhanced ChAT activity in the septal neurons. These results suggest that TAK-147 may have neurotrophic activity on central cholinergic neurons, not via AChE inhibition but possibly via an effect on tau receptors.

Present imperfect: a critical review of animal models of the mnemonic impairments in Alzheimer's disease

This paper reviews the current literature on animal models of the memory impairments of Alzheimer's disease (AD). The authors suggest that modeling of the mnemonic deficits in AD be limited to the amnesia observed early in the course of the disease, to eliminate the influence of impairments in non-mnemonic processes. Tasks should be chosen for their specificity and selectivity to the behavioral phenomena observed in early-stage AD and not for their relevance to hypothetical mnemonic processes. Tasks that manipulate the delay between learning and remembering are better able to differentiate Alzheimer patients from persons with other disorders, and better able to differentiate effects of manipulations in animals. The most commonly used manipulations that attempt to model the amnesia of AD are reviewed within these constraints. The authors conclude that of the models examined, lesions of the medial septal nucleus produce behavioral deficits that are most similar to the mnemonic impairments in the earliest stage of AD. However, the parallel is not definitive and more work is needed to clarify the relationship between neurobiology and behavior in AD.

The novel compound TDN-345 induces synthesis/secretion of nerve growth factor in C6-10A glioma cells

A novel compound, TDN-345, not bearing catechol moiety, induced NGF synthesis/secretion in C6-10A glioma cells. Both intracellular and extracellular nerve growth factor (NGF) protein levels increased within 3 h and reached a maximum around 12 h after the addition of TDN-345. The induction of NGF synthesis/secretion by TDN-345 occurred in a concentration-dependent manner, beginning with about 0.1 microM and reaching a maximum at 10 microM. The ED50 was 0.88 microM. The induction was accompanied by an increase in NGF mRNA but not beta-actin mRNA. In a time-course study, the NGF mRNA level was found to reach a maximum 2-3 h after the addition of TDN-345 and then to return to control levels. The induction occurred dose-dependently. The catecholaminergic compound epinephrine, which induces NGF synthesis/secretion, increased the intracellular cyclic AMP content by more than 1000-times at 10 microM. In contrast, TDN-345 did not cause such a prominent increase in cAMP even at 100 microM. These results indicate that TDN-345 induces NGF synthesis/secretion by increasing NGF mRNA expression, and the action of TDN-345 clearly differs from that of epinephrine, as it does not seem to involve cAMP as a second messenger. The results of the present study suggest the existence of a signal transduction pathway for NGF synthesis/secretion which is not mediated by cAMP.

Characterization of C6-10A glioma cells highly responsive to beta-adrenergic receptor agonist-induced NGF synthesis/secretion

A subline of rat C6 glioma cells, C6-10A cells, in which epinephrine can induce nerve growth factor (NGF) synthesis/secretion, was isolated. C6-10A cells have retained their sensitivity to epinephrine for more than 2 years in a medium containing 0.5% fetal calf serum (FCS) but easily lose it in 10% FCS. C6-10A cells are S-100- and glial fibrillary acidic protein-positive, and the doubling time is about 60 h in the medium containing 0.5% FCS and about 20 h in 10% FCS. Epinephrine induced NGF synthesis/secretion prominently in serum-free cultures of C6-10A cells and in cultures with a high cell density, but not in serum-containing cultures. The induction did not occur with parent C6 cells under the appropriate conditions in C6-10A cells. NGF secretion was induced by catecholaminergic compounds in the following order isoproterenol > epinephrine = norepinephrine >> dopamine. The induction caused by epinephrine was blocked by propranolol (beta-blocker) but not by phentolamine (alpha-blocker). Various compounds that activate the adenylate cyclase system also induced NGF synthesis/secretion. These results indicate that C6-10A cells are astrocytes that are highly responsive to beta-adrenergic receptor agonists, which stimulate NGF synthesis/secretion via receptors coupled with adenylate cyclase machinery. These cells may be a useful aid in studying the mechanism of NGF synthesis/secretion.