A Phase 1 study of ADI-PEG20 (pegargiminase) combined with cisplatin and pemetrexed in ASS1-negative metastatic uveal melanoma

Opportunities for nanomaterials in enzyme therapy

In recent years, enzyme therapy strategies have rapidly evolved to catalyze essential biochemical reactions with therapeutic potential. These approaches hold particular promise in addressing rare genetic disorders, cancer treatment, neurodegenerative conditions, wound healing, inflammation management, and infectious disease control, among others. There are several primary reasons for the utilization of enzymes as therapeutics: their substrate specificity, their biological compatibility, and their ability to generate a high number of product molecules per enzyme unit. These features have encouraged their application in enzyme replacement therapy where the enzyme serves as the therapeutic agent to rectify abnormal metabolic and physiological processes, enzyme prodrug therapy where the enzyme initiates a clinical effect by activating prodrugs, and enzyme dynamic or starving therapy where the enzyme acts upon host substrate molecules. Currently, there are >20 commercialized products based on therapeutic enzymes, but approval rates are considerably lower than other biologicals. This has stimulated nanobiotechnology in the last years to develop nanoparticle-based solutions that integrate therapeutic enzymes. This approach aims to enhance stability, prevent rapid clearance, reduce immunogenicity, and even enable spatio-temporal activation of the therapeutic catalyst. This comprehensive review delves into emerging trends in the application of therapeutic enzymes, with a particular emphasis on the synergistic opportunities presented by incorporating enzymes into nanomaterials. Such integration holds the promise of enhancing existing therapies or even paving the way for innovative nanotherapeutic approaches.

Causal relationship between genetically determined plasma metabolites and skin cancer: a two-sample Mendelian randomization study

We aimed to unveil the underlying pathogenic mechanisms of skin cancer in relation to metabolic factors and pathway mechanisms. This study utilized the TwoSample Mendelian randomization (MR) method to investigate the causal relationship between 1400 plasma metabolites and skin cancer. The primary method employed was the inverse variance weighting (IVW). Through IVW analysis, we found 105 plasma metabolites associated with Basal Cell Carcinoma (BCC), with the highest association observed for Prolylglycine levels (OR [95% CI]: 1.1902 [1.0274, 1.3788]). For Malignant Melanoma of Skin (MSS), 68 plasma metabolites were linked, with the highest causal relationship seen for 3-Hydroxybutyrate levels (OR [95% CI]: 1.0030 [1.0013, 1.0048]). Regarding actinic keratosis (AK), and the highest association observed for Hexadecadienoate (16:2n6) levels (OR [95% CI]: 1.3302 [1.0333, 1.7125]). Glycerol to palmitoylcarnitine (16: n6) levels (OR [95% CI]: 1.3302 [1.0333, 1.125]) were found to be significant for BCC and AK. Palmitoylcarnitine (C16) had the most positive causal effect for BCC (OR [95% CI]: 1.1777 [1.0493, 1.3218]), while 5-hydroxy-2-methylpyridine sulfate levels had the highest effect for AK (OR [95% CI]: 1.1788 [1.0295, 1.3498]). And 4-guanidinobutanoate levels had the largest positive causal effect (OR [95% CI]: 1.0857 [1.0417, 1.1317]) for BCC, and X-11880 levels for MSS (OR [95% CI]: 1.0013 [1.0000, 1.0025]). The study revealed a positive association between hereditary Glycerol to palmitoylcarnitine (C16) and 5-hydroxy-2-methylpyridine sulfate levels with the risk of developing BCC and AK. Additionally, 4-guanidinobutanoate levels and X 11880 levels were found to be positively associated with the risk of BCC and MMS.

Arginine deprivation enriches lung cancer proteomes with cysteine by inducing arginine-to-cysteine substitutants

Many types of human cancers suppress the expression of argininosuccinate synthase 1 (ASS1), a rate-limiting enzyme for arginine production. Although dependency on exogenous arginine can be harnessed by arginine-deprivation therapies, the impact of ASS1 suppression on the quality of the tumor proteome is unknown. We therefore interrogated proteomes of cancer patients for arginine codon reassignments (substitutants) and surprisingly identified a strong enrichment for cysteine (R>C) in lung tumors specifically. Most R>C events did not coincide with genetically encoded R>C mutations but were likely products of tRNA misalignments. The expression of R>C substitutants was highly associated with oncogenic kelch-like epichlorohydrin (ECH)-associated protein 1 (KEAP1)-pathway mutations and suppressed by intact-KEAP1 in KEAP1-mutated cancer cells. Finally, functional interrogation indicated a key role for R>C substitutants in cell survival to cisplatin, suggesting that regulatory codon reassignments endow cancer cells with more resilience to stress. Thus, we present a mechanism for enriching lung cancer proteomes with cysteines that may affect therapeutic decisions.

Arginase-induced cell death pathways and metabolic changes in cancer cells are not altered by insulin

Arginine, a semi-essential amino acid, is critical for cell growth. Typically, de novo synthesis of arginine is sufficient to support cellular processes, however, it becomes vital for cancer cells that are unable to synthesise arginine due to enzyme deficiencies. Targeting this need, arginine depletion with enzymes such as arginase (ARG) has emerged as a potential cancer therapeutic strategy. Studies have proposed using high dose insulin to induce a state of hypoaminoacidaemia in the body, thereby further reducing circulating arginine levels. However, the mitogenic and metabolic properties of insulin could potentially counteract the therapeutic effects of ARG. Our study examined the combined impact of insulin and ARG on breast, lung, and ovarian cell lines, focusing on cell proliferation, metabolism, apoptosis, and autophagy. Our results showed that the influence of insulin on ARG uptake varied between cell lines but failed to promote the proliferation of ARG-treated cells or aid recovery post-ARG treatment. Moreover, insulin was largely ineffective in altering ARG-induced metabolic changes and did not prevent apoptosis. In vitro, at least, these findings imply that insulin does not offer a growth or survival benefit to cancer cells being treated with ARG.

Preclinical and clinical developments in enzyme-loaded red blood cells: an update

INTRODUCTION

We have previously described the preclinical developments in enzyme-loaded red blood cells to be used in the treatment of several rare diseases, as well as in chronic conditions.

AREA COVERED

Since our previous publication we have seen further progress in the previously discussed approaches and, interestingly enough, in additional new studies that further strengthen the idea that red blood cell-based therapeutics may have unique advantages over conventional enzyme replacement therapies in terms of efficacy and safety. Here we highlight these investigations and compare, when possible, the reported results versus the current therapeutic approaches.

EXPERT OPINION

The continuous increase in the number of new potential applications and the progress from the encapsulation of a single enzyme to the engineering of an entire metabolic pathway open the field to unexpected developments and confirm the role of red blood cells as cellular bioreactors that can be conveniently manipulated to acquire useful therapeutic metabolic abilities. Positioning of these new approaches versus newly approved drugs is essential for the successful transition of this technology from the preclinical to the clinical stage and hopefully to final approval.

Unlocking the Potential of Arginine Deprivation Therapy: Recent Breakthroughs and Promising Future for Cancer Treatment

Arginine is a semi-essential amino acid that supports protein synthesis to maintain cellular functions. Recent studies suggest that arginine also promotes wound healing, cell division, ammonia metabolism, immune system regulation, and hormone biosynthesis-all of which are critical for tumor growth. These discoveries, coupled with the understanding of cancer cell metabolic reprogramming, have led to renewed interest in arginine deprivation as a new anticancer therapy. Several arginine deprivation strategies have been developed and entered clinical trials. The main principle behind these therapies is that arginine auxotrophic tumors rely on external arginine sources for growth because they carry reduced key arginine-synthesizing enzymes such as argininosuccinate synthase 1 (ASS1) in the intracellular arginine cycle. To obtain anticancer effects, modified arginine-degrading enzymes, such as PEGylated recombinant human arginase 1 (rhArg1-PEG) and arginine deiminase (ADI-PEG 20), have been developed and shown to be safe and effective in clinical trials. They have been tried as a monotherapy or in combination with other existing therapies. This review discusses recent advances in arginine deprivation therapy, including the molecular basis of extracellular arginine degradation leading to tumor cell death, and how this approach could be a valuable addition to the current anticancer arsenal.

Nanotechnology Lighting the Way for Gene Therapy in Ophthalmopathy: From Opportunities toward Applications

Hereditary ophthalmopathy is a well-described threat to human visual health affecting millions of people. Gene therapy for ophthalmopathy has received widespread attention with the increasing understanding of pathogenic genes. Effective and safe delivery of accurate nucleic acid drugs (NADs) is the core of gene therapy. Efficient nanodelivery and nanomodification technologies, appropriate targeted genes, and the choice of drug injection methods are the guiding lights of gene therapy. Compared with traditional drugs, NADs can specifically change the expression of specific genes or restore the normal function of mutant genes. Nanodelivery carriers can improve targeting and nanomodification can improve the stability of NADs. Therefore, NADs, which can fundamentally solve pathogeny, hold great promise in the treatment of ophthalmopathy. This paper reviews the limitations of ocular disease treatment, discusses the classification of NADs in ophthalmology, reveals the delivery strategies of NADs to improve bioavailability, targeting, and stability, and summarizes the mechanisms of NADs in ophthalmopathy.

Bench-to-Bedside Studies of Arginine Deprivation in Cancer

Arginine is a semi-essential amino acid which becomes wholly essential in many cancers commonly due to the functional loss of Argininosuccinate Synthetase 1 (ASS1). As arginine is vital for a plethora of cellular processes, its deprivation provides a rationale strategy for combatting arginine-dependent cancers. Here we have focused on pegylated arginine deiminase (ADI-PEG20, pegargiminase)-mediated arginine deprivation therapy from preclinical through to clinical investigation, from monotherapy to combinations with other anticancer therapeutics. The translation of ADI-PEG20 from the first in vitro studies to the first positive phase 3 trial of arginine depletion in cancer is highlighted. Finally, this review discusses how the identification of biomarkers that may denote enhanced sensitivity to ADI-PEG20 beyond ASS1 may be realized in future clinical practice, thus personalising arginine deprivation therapy for patients with cancer.

Argininosuccinate synthase 1, arginine deprivation therapy and cancer management

Metabolic reprogramming is an emerging hallmark of tumor cells. In order to survive in the nutrient-deprived environment, tumor cells rewire their metabolic phenotype to provide sufficient energy and build biomass to sustain their transformed state and promote malignant behaviors. Amino acids are the main compositions of protein, which provide key intermediate substrates for the activation of signaling pathways. Considering that cells can synthesize arginine via argininosuccinate synthase 1 (ASS1), arginine is regarded as a non-essential amino acid, making arginine depletion as a promising therapeutic strategy for ASS1-silencing tumors. In this review, we summarize the current knowledge of expression pattern of ASS1 and related signaling pathways in cancer and its potential role as a novel therapeutic target in cancer. Besides, we outline how ASS1 affects metabolic regulation and tumor progression and further discuss the role of ASS1 in arginine deprivation therapy. Finally, we review approaches to target ASS1 for cancer therapies.