Safety, pharmacokinetics, and pharmacodynamics of nomlabofusp (CTI-1601) in Friedreich's ataxia

OBJECTIVE

Current treatments for Friedreich's ataxia, a neurodegenerative disorder characterized by decreased intramitochondrial frataxin, do not address low frataxin concentrations. Nomlabofusp (previously CTI-1601) is a frataxin replacement therapy with a unique mechanism of action that directly addresses this underlying frataxin deficiency. Phase 1 studies assessed the safety, pharmacokinetic, and pharmacodynamic profiles of subcutaneously administered nomlabofusp in adults with Friedreich's ataxia.

METHODS

Patients were enrolled in two Phase 1, double-blind, placebo-controlled studies. The single ascending-dose (SAD) study (NCT04176991) evaluated single doses of nomlabofusp (25, 50, 75, or 100 mg) or placebo. The multiple ascending-dose (MAD) study (NCT04519567) evaluated nomlabofusp (25 mg daily for 4 days then every third day, 50 mg daily for 7 days then every 2 days, or 100 mg daily) or placebo for 13 days.

RESULTS

Patients aged 19-69 years were enrolled (SAD, N = 28; MAD, N = 27). Nomlabofusp was generally well tolerated through 13 days. Most adverse events were mild and resolved quickly. No serious adverse events or deaths were reported. Peak nomlabofusp plasma concentrations occurred 15 min after subcutaneous administration. Nomlabofusp plasma exposures increased with increasing doses and daily administration and decreased with reduced dosing frequency. Increased frataxin concentrations were observed in buccal cells, skin, and platelets with higher and more frequent nomlabofusp administration.

INTERPRETATION

Results from this study support a favorable safety profile for nomlabofusp. Subcutaneous nomlabofusp injections were quickly absorbed; higher doses and daily administration resulted in increased tissue frataxin concentrations. Future studies will evaluate longer-term safety and possible efficacy of nomlabofusp.

2022 White Paper on Recent Issues in Bioanalysis: FDA Draft Guidance on Immunogenicity Information in Prescription Drug Labeling, LNP & Viral Vectors Therapeutics/Vaccines Immunogenicity, Prolongation Effect, ADA Affinity, Risk-based Approaches, NGS, qPCR, ddPCR Assays (Part 3 - Recommendations on Gene Therapy, Cell Therapy, Vaccines Immunogenicity & Technologies; Immunogenicity & Risk Assessment of Biotherapeutics and Novel Modalities; NAb Assays Integrated Approach)

The 2022 16th Workshop on Recent Issues in Bioanalysis (WRIB) took place in Atlanta, GA, USA on September 26-30, 2022. Over 1000 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 16th WRIB included 3 Main Workshops and 7 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 ICH M10 BMV final guideline (focused on this guideline training, interpretation, adoption and transition); mass spectrometry innovation (focused on novel technologies, novel modalities, and novel challenges); and flow cytometry bioanalysis (rising of the 3rd most common/important technology in bioanalytical labs) were the special features of the 16th edition. As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues. This 2022 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 2022 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers the recommendations on Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity. Part 1 (Mass Spectrometry and ICH M10) and Part 2 (LBA, Biomarkers/CDx and Cytometry) are published in volume 15 of Bioanalysis, issues 16 and 15 (2023), respectively.

Abstract 5341: Bifunctional integrated molecules with combined retinoic acid receptor agonist/protein deacetylase inhibitory activities as therapeutic agents for breast cancer and neuroblastoma

All-trans retinoic acid (ATRA), the oxidized form of Vitamin A, is a potent antiproliferative and differentiating agent that acts as an agonist of the retinoic acid receptors (RARs). Both 13-cis or all-trans retinoic acid are clinically used in differentiation or maintenance therapies for APL and neuroblastoma respectively. Their efficacy is however limited by resistance mechanisms. The use of small molecule inhibitors of HDACs (HDACi) for cancer treatment has been clinically validated for pan-HDAC inhibitors like SAHA (Vorinostat) or Romidepsin (Istodax) that are approved for the treatment of cutaneous T-cell lymphoma. The use of pan-HDAC inhibitors is restricted by dose-limiting toxicities at pharmacologically relevant doses, highlighting the need for alternative strategies such as use in combined therapies. Notably, synergistic activity was observed between retinoids and HDACs, which both induce cell differentiation, in a number of cancer models. Using molecular design we engineered a series of integrated hybrid small molecules that incorporates a deacetylase inhibitory activity and retinoic acid receptor (RAR) agonist. We show that these hybrid molecules inhibit the growth and survival of a wide range of cancer cell lines.

In breast cancer cell lines, hybrids were shown to induce the recruitment of co-activators to RARα to the same extent as retinoic acid (RA) and to induce the release of co-repressors from RARs. Regulation of RAR-dependent transcription was shown in breast cancer and neuroblastoma cell lines using RAR reporter assays. Compounds displayed EC50 in the 10-500 nM range and an efficacy comparable to 13 cis-RA. In addition, the ability of compounds to regulate the expression of RAR target genes was confirmed in cells of both breast and neuroblastoma origin. Biochemical enzymatic assays show that HR- hybrids differentially inhibit HDAC activities with a two-log selectivity toward HDAC6 and HDAC. This inhibitory profile translated in both increased cellular acetylation of target proteins and in the down-regulation of anti-apoptotic target genes.

Cytotoxicity toward breast or neuroblastoma cells correlated positively with targets’ activities. Strikingly, under conditions where 13 cis RA, SAHA or their combination had a modest or no effect on basal breast carcinoma cells viability, compounds with dual activity displayed a pronounced cytotoxic effect in the sub-uM range. Compounds were also active in the sub-micromolar range in N-Myc-amplified neuroblastoma lines IMR-32 or BE2C. In contrast compounds did not display significant cytotoxicity in non-tumorigenic primary cell lines under conditions where SAHA strongly inhibited the survival, proliferation or differentiation of these cells. Preliminary pharmacodynamic (PK) show that compounds were orally bioavailable and displayed favorable PK characteristics.

Citation Format: David Cotnoir-White, Angela Miller, Bin Zhao, Isroel Weiss, James Gleason, David Bettoun, Sylvie Mader. Bifunctional integrated molecules with combined retinoic acid receptor agonist/protein deacetylase inhibitory activities as therapeutic agents for breast cancer and neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5341. doi:10.1158/1538-7445.AM2015-5341

Discovery of novel cyanamide-based inhibitors of cathepsin C

The discovery of potent and selective cyanamide-based inhibitors of the cysteine protease cathepsin C is detailed. Optimization of the template with regard to plasma stability led to the identification of compound 17, a potent cathepsin C inhibitor with excellent selectivity over other cathepsins and potent in vivo activity in a cigarette smoke mouse model.

Phylogenesis and regulated expression of the RUNT domain transcription factors RUNX1 and RUNX3

The RUNX transcription factors are key regulators of lineage specific gene expression in developmental pathways. The mammalian RUNX genes arose early in evolution and maintained extensive structural similarities. Sequence analysis suggested that RUNX3 is the most ancient of the three mammalian genes, consistent with its role in neurogenesis of the monosynaptic reflex arc, the simplest neuronal response circuit, found in Cnidarians, the most primitive animals. All RUNX proteins bind to the same DNA motif and act as activators or repressors of transcription through recruitment of common transcriptional modulators. Nevertheless, analysis of Runx1 and Runx3 expression during embryogenesis revealed that their function is not redundant. In adults both Runx1 and Runx3 are highly expressed in the hematopoietic system. At early embryonic stages we found strong Runx3 expression in dorsal root ganglia neurons, confined to TrkC sensory neurons. In the absence of Runx3, knockout mice develop severe ataxia due to the early death of the TrkC neurons. Other phenotypic defects of Runx3 KO mice including abnormalities in thymopoiesis are also being investigated.

The Runx3 transcription factor regulates development and survival of TrkC dorsal root ganglia neurons

The RUNX transcription factors are important regulators of linage-specific gene expression in major developmental pathways. Recently, we demonstrated that Runx3 is highly expressed in developing cranial and dorsal root ganglia (DRGs). Here we report that within the DRGs, Runx3 is specifically expressed in a subset of neurons, the tyrosine kinase receptor C (TrkC) proprioceptive neurons. We show that Runx3-deficient mice develop severe limb ataxia due to disruption of monosynaptic connectivity between intra spinal afferents and motoneurons. We demonstrate that the underlying cause of the defect is a loss of DRG proprioceptive neurons, reflected by a decreased number of TrkC-, parvalbumin- and beta-galactosidase-positive cells. Thus, Runx3 is a neurogenic TrkC neuron-specific transcription factor. In its absence, TrkC neurons in the DRG do not survive long enough to extend their axons toward target cells, resulting in lack of connectivity and ataxia. The data provide new genetic insights into the neurogenesis of DRGs and may help elucidate the molecular mechanisms underlying somatosensory-related ataxia in humans.

Spatial and temporal expression pattern of Runx3 (Aml2) and Runx1 (Aml1) indicates non-redundant functions during mouse embryogenesis

The human RUNX3/AML2 gene belongs to the 'runt domain' family of transcription factors that act as gene expression regulators in major developmental pathways. Here, we describe the expression pattern of Runx3 during mouse embryogenesis compared to the expression pattern of Runx1. E10.5 and E14.5-E16.5 embryos were analyzed using both immunohistochemistry and beta-galactosidase activity of targeted Runx3 and Runx1 loci. We found that Runx3 expression overlapped with that of Runx1 in the hematopoietic system, whereas in sensory ganglia, epidermal appendages, and developing skeletal elements, their expression was confined to different compartments. These data provide new insights into the function of Runx3 and Runx1 in organogenesis and support the possibility that cross-regulation between them plays a role in embryogenesis.