Use of polymer conjugates for the intraperoxisomal delivery of engineered human alanine:glyoxylate aminotransferase as a protein therapy for primary hyperoxaluria type I

Navigating the Evolving Landscape of Primary Hyperoxaluria: Traditional Management Defied by the Rise of Novel Molecular Drugs

Primary hyperoxalurias (PHs) are inherited metabolic disorders marked by enzymatic cascade disruption, leading to excessive oxalate production that is subsequently excreted in the urine. Calcium oxalate deposition in the renal tubules and interstitium triggers renal injury, precipitating systemic oxalate build-up and subsequent secondary organ impairment. Recent explorations of novel therapeutic strategies have challenged and necessitated the reassessment of established management frameworks. The execution of diverse clinical trials across various medication classes has provided new insights and knowledge. With the evolution of PH treatments reaching a new milestone, prompt and accurate diagnosis is increasingly critical. Developing early, effective management and treatment plans is essential to improve the long-term quality of life for PH patients.

Poly-l-glutamic acid modification modulates the bio-nano interface of a therapeutic anti-IGF-1R antibody in prostate cancer

Modifying biological agents with polymers such as polyethylene glycol (PEG) has demonstrated clinical benefits; however, post-market surveillance of PEGylated derivatives has revealed PEG-associated toxicity issues, prompting the search for alternatives. We explore how conjugating a poly-l-glutamic acid (PGA) to an anti-insulin growth factor 1 receptor antibody (AVE1642) modulates the bio-nano interface and anti-tumor activity in preclinical prostate cancer models. Native and PGA-modified AVE1642 display similar anti-tumor activity in vitro; however, AVE1642 prompts IGF-1R internalization while PGA conjugation prompts higher affinity IGF-1R binding, thereby inhibiting IGF-1R internalization and altering cell trafficking. AVE1642 attenuates phosphoinositide 3-kinase signaling, while PGA-AVE1642 inhibits phosphoinositide 3-kinase and mitogen-activated protein kinase signaling. PGA conjugation also enhances AVE1642's anti-tumor activity in an orthotopic prostate cancer mouse model, while PGA-AVE1642 induces more significant suppression of cancer cell proliferation/angiogenesis than AVE1642. These findings demonstrate that PGA conjugation modulates an antibody's bio-nano interface, mechanism of action, and therapeutic activity.

Prospects of Using Protein Engineering for Selective Drug Delivery into a Specific Compartment of Target Cells

A large number of proteins are successfully used to treat various diseases. These include natural polypeptide hormones, their synthetic analogues, antibodies, antibody mimetics, enzymes, and other drugs based on them. Many of them are demanded in clinical settings and commercially successful, mainly for cancer treatment. The targets for most of the aforementioned drugs are located at the cell surface. Meanwhile, the vast majority of therapeutic targets, which are usually regulatory macromolecules, are located inside the cell. Traditional low molecular weight drugs freely penetrate all cells, causing side effects in non-target cells. In addition, it is often difficult to elaborate a small molecule that can specifically affect protein interactions. Modern technologies make it possible to obtain proteins capable of interacting with almost any target. However, proteins, like other macromolecules, cannot, as a rule, freely penetrate into the desired cellular compartment. Recent studies allow us to design multifunctional proteins that solve these problems. This review considers the scope of application of such artificial constructs for the targeted delivery of both protein-based and traditional low molecular weight drugs, the obstacles met on the way of their transport to the specified intracellular compartment of the target cells after their systemic bloodstream administration, and the means to overcome those difficulties.

Chitosan Derivatives as Nanocarriers for hLDHA Inhibitors Delivery to Hepatic Cells: A Selective Strategy for Targeting Primary Hyperoxaluria Diseases

Primary hyperoxalurias (PHs) are a group of inherited alterations of the hepatic glyoxylate metabolism that result in an excess of oxalate production by the oxidation of glyoxylate by the human lactate dehydrogenase A enzyme (hLDHA). The selective liver inhibition of this enzyme is one of the therapeutic strategies followed in the treatment of this disease. Even though several efforts have been recently performed using gene silencing by the RNA interference approach, small-molecule inhibitors that selectively reach hepatocytes are preferred since they present the advantages of a lower production cost and better pharmacological properties. In that sense, the design, synthesis, and physicochemical characterization by NMR, FTIR, DLS and TEM of two nanocarriers based on chitosan conjugates (1, non-redox-sensitive; 2, redox-sensitive) have been performed to (i) achieve the selective transport of hLDHA inhibitors into hepatocytes and (ii) their disruption once they reach the hepatocytes cytosol. Polymer 2 self-assembled into micelles in water and showed high drug loadings (19.8-24.5%) and encapsulation efficiencies (31.9-40.8%) for the hLDHA inhibitors (I-III) tested. The non-redox-sensitive micelle 1 remained stable under different glutathione (GSH) concentrations (10 μM and 10 mM), and just a residual release of the inhibitor encapsulated was observed (less than 10%). On the other hand, micelle 2 was sufficiently stable under in vitro physiological conditions (10 μM, GSH) but it quickly disassembled under the simulated reducing conditions present inside hepatocytes (10 mM GSH), achieving a 60% release of the hLDHA inhibitor encapsulated after 24 h, confirming the responsiveness of the developed carrier to the high levels of intracellular GSH.

Perspectives in primary hyperoxaluria - historical, current and future clinical interventions

Primary hyperoxalurias are a devastating family of diseases leading to multisystem oxalate deposition, nephrolithiasis, nephrocalcinosis and end-stage renal disease. Traditional treatment paradigms are limited to conservative management, dialysis and combined transplantation of the kidney and liver, of which the liver is the primary source of oxalate production. However, transplantation is associated with many potential complications, including operative risks, graft rejection, post-transplant organ failure, as well as lifelong immunosuppressive medications and their adverse effects. New therapeutics being developed for primary hyperoxalurias take advantage of biochemical knowledge about oxalate synthesis and metabolism, and seek to specifically target these pathways with the goal of decreasing the accumulation and deposition of oxalate in the body.

Primary hyperoxalurias are a devastating family of diseases that eventually lead to end-stage renal disease. In this Review, Shee and Stoller discuss current treatment paradigms for primary hyperoxalurias, new therapeutics and their mechanisms of action, and future directions for novel research in the field.

Primary hyperoxalurias (PHs) are a devastating family of rare, autosomal-recessive genetic disorders that lead to multisystem oxalate deposition, nephrolithiasis, nephrocalcinosis and end-stage renal disease.

Traditional treatment paradigms are limited to conservative management, dialysis and inevitably transplantation of the kidney and liver, which is associated with high morbidity and the need for lifelong immunosuppression.

New therapeutics being developed for PHs take advantage of biochemical knowledge about oxalate synthesis and metabolism to specifically target these pathways, with the goal of decreasing the accumulation and deposition of plasma oxalate in the body.

New therapeutics can be divided into classes, and include substrate reduction therapy, intestinal oxalate degradation, chaperone therapy, enzyme restoration therapy and targeting of the inflammasome.

Lumasiran, a mRNA therapeutic targeting glycolate oxidase, was the first primary hyperoxaluria-specific therapeutic approved by the European Medicines Agency and the FDA in 2020.

Future work includes further clinical trials for promising therapeutics in the pipeline, identification of biomarkers of response to PH-directed therapy, optimization of drug development and delivery of new therapeutics.

Novel therapeutic approaches for the primary hyperoxalurias

Loss-of-function mutations in three genes, involved in the metabolic pathway of glyoxylate, result in increased oxalate production and its crystallization in the form of calcium oxalate. This leads to three forms of primary hyperoxaluria-an early-onset inherited kidney disease with wide phenotypic variability ranging from isolated kidney stone events to stage 5 chronic kidney disease in infancy. This review provides a description of metabolic processes resulting in oxalate overproduction and summarizes basic therapeutic approaches. Unfortunately, current treatment of primary hyperoxaluria does not allow the prevention of loss of kidney function or to substantially diminish other symptoms in most patients. However, latest breakthroughs in biotechnology provide new promising directions for drug development. Some of them have already progressed to the level of clinical trials; others are just at the stage of proof of concept. Here we review the most advanced technologies including those that have been harnessed as possible therapeutic modalities.

Small Molecule-Based Enzyme Inhibitors in the Treatment of Primary Hyperoxalurias

Primary hyperoxalurias (PHs) are a group of inherited alterations of the hepatic glyoxylate metabolism. PHs classification based on gene mutations parallel a variety of enzymatic defects, and all involve the harmful accumulation of calcium oxalate crystals that produce systemic damage. These geographically widespread rare diseases have a deep impact in the life quality of the patients. Until recently, treatments were limited to palliative measures and kidney/liver transplants in the most severe forms. Efforts made to develop pharmacological treatments succeeded with the biotechnological agent lumasiran, a siRNA product against glycolate oxidase, which has become the first effective therapy to treat PH1. However, small molecule drugs have classically been preferred since they benefit from experience and have better pharmacological properties. The development of small molecule inhibitors designed against key enzymes of glyoxylate metabolism is on the focus of research. Enzyme inhibitors are successful and widely used in several diseases and their pharmacokinetic advantages are well known. In PHs, effective enzymatic targets have been determined and characterized for drug design and interesting inhibitory activities have been achieved both in vitro and in vivo. This review describes the most recent advances towards the development of small molecule enzyme inhibitors in the treatment of PHs, introducing the multi-target approach as a more effective and safe therapeutic option.

Robust and smart polypeptide-based nanomedicines for targeted tumor therapy

Nanomedicines based on synthetic polypeptides are among the most versatile and advanced platforms for tumor therapy. Notably, several polypeptide-based nanodrugs are currently under human clinical assessments. The previous (pre)clinical studies clearly show that dynamic stability (i.e. stable in circulation while destabilized in tumor) of nanomedicines plays a vital role in their anti-tumor performance. Various strategies have recently been developed to design dynamically stabilized polypeptide-based nanomedicines by e.g. crosslinking the nanovehicles with acid, reactive oxygen species (ROS), glutathione (GSH), or photo-sensitive linkers, inter-crosslinking between vehicles and drugs, introducing π-π stacking or lipid-lipid interactions in the nanovehicles, chemically conjugating drugs to vehicles, and forming unimolecular micelles. Interestingly, these robust and smart nanodrugs have demonstrated improved tumor targetability, anti-tumor efficacy, as well as safety profiles in different tumor models. In this review, representative strategies to robust and smart polypeptide-based nanomedicines for targeted treatment of varying malignancies are highlighted. The exciting development of dynamic nanomedicines will foresee further increasing clinical translation in the future.

Therapeutic potential of polypeptide-based conjugates: Rational design and analytical tools that can boost clinical translation

The clinical success of polypeptides as polymeric drugs, covered by the umbrella term "polymer therapeutics," combined with related scientific and technological breakthroughs, explain their exponential growth in the development of polypeptide-drug conjugates as therapeutic agents. A deeper understanding of the biology at relevant pathological sites and the critical biological barriers faced, combined with advances regarding controlled polymerization techniques, material bioresponsiveness, analytical methods, and scale up-manufacture processes, have fostered the development of these nature-mimicking entities. Now, engineered polypeptides have the potential to combat current challenges in the advanced drug delivery field. In this review, we will discuss examples of polypeptide-drug conjugates as single or combination therapies in both preclinical and clinical studies as therapeutics and molecular imaging tools. Importantly, we will critically discuss relevant examples to highlight those parameters relevant to their rational design, such as linking chemistry, the analytical strategies employed, and their physicochemical and biological characterization, that will foster their rapid clinical translation.

Direct Drug Targeting into Intracellular Compartments: Issues, Limitations, and Future Outlook

Intracellular compartment drug delivery is a promising strategy for the treatment of diseases. By this way, medicines can delivered to particular intracellular compartments. This maximizes the therapeutic efficacy and safety of medicines, particularly of anticancer and antiviral drugs. Intracellular compartment drug delivery is either indirectly by targeting of cell nucleus as central compartment of the cell or directly through the targeting of compartments itself. Drugs or nanoshuttles labeled with compartment's localization signal represent a smart tactic for subcellular compartment targeting. There are several boundaries prevent the arrival of shuttles to the specified intracellular compartments. These boundaries include selective permeability of biomembranes, efflux transporters, and lysosomes. The utilization of specific ligands during design of drug delivery nanoshuttles permits the targeting of specified intracellular compartment. Therefore drugs targeting could correct the diseases associated organelles. This review highlights the direct targeting of the medicines into subcellular compartment as a promising therapeutic strategy.

Primary hyperoxaluria diagnosed after kidney transplantation failure: lesson from 3 case reports and literature review

Background

Primary hyperoxaluria (PH) is a rare inborn disorder of the metabolism of glyoxylate, which causes the hallmark production oxalate and forms insoluble calcium oxalate crystals that accumulate in the kidney and other organs. Since the manifestation of PH varies from recurrent nephrolithiasis, nephrocalcinosis, and end-stage renal disease with age at onset of symptoms ranging from infancy to the sixth decade, the disease remains undiagnosed until after kidney transplantation in some cases.

Case presentation

Herein, we report 3 cases of PH diagnosed after kidney transplantation failure, providing the comprehensive clinical course, the ultrasonic image of renal graft and pathologic image of the biopsy, highlighting the relevance of biopsy findings and the results of molecular genetic testing. We also focus on the treatment and the unfavorable outcome of the patients. Meanwhile, we review the literature and show the additional 10 reported cases of PH diagnosed after kidney transplantation. Additionally, we discuss the progressive molecular understanding of the mechanisms involved in PH and molecular therapy.

Conclusions

Overall, the necessity of preoperative screening of PH in all patients even with a minor history of nephrolithiasis and the importance of proper treatment are the lessons we learn from the 3 cases, which prompt us to avoid tragedies.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1402-2) contains supplementary material, which is available to authorized users.

Molecular basis of primary hyperoxaluria: clues to innovative treatments

Primary hyperoxalurias (PHs) are rare inherited disorders of liver glyoxylate metabolism, characterized by the abnormal production of endogenous oxalate, a metabolic end-product that is eliminated by urine. The main symptoms are related to the precipitation of calcium oxalate crystals in the urinary tract with progressive renal damage and, in the most severe form named Primary Hyperoxaluria Type I (PH1), to systemic oxalosis. The therapies currently available for PH are either poorly effective, because they address the symptoms and not the causes of the disease, or highly invasive. In the last years, advances in our understanding of the molecular bases of PH have paved the way for the development of new therapeutic strategies. They include (i) substrate-reduction therapies based on small-molecule inhibitors or the RNA interference technology, (ii) gene therapy, (iii) enzyme administration approaches, (iv) colonization with oxalate-degrading intestinal microorganisms, and, in PH1, (v) design of pharmacological chaperones. This paper reviews the basic principles of these new therapeutic strategies and what is currently known about their application to PH.

Peroxisomal disorders: Improved laboratory diagnosis, new defects and the complicated route to treatment

Peroxisomes catalyze a number of essential metabolic functions of which fatty acid alpha- and beta-oxidation, ether phospholipid biosynthesis, glyoxylate detoxification and bile acid synthesis are the most important. The key role of peroxisomes in humans is exemplified by the existence of a group of peroxisomal disorders, caused by mutations in > 30 different genes which code for proteins with a role in either peroxisome biogenesis or one of the metabolic pathways in peroxisomes. Technological advances in laboratory methods at the metabolite-, enzyme-, and molecular level have not only allowed the identification of new peroxisomal disorders but also new phenotypes associated with already identified genetic defects thus extending the clinical spectrum. Unfortunately, progress in the field of pathogenesis and treatment has lagged behind although there are certainly new and hopeful developments with respect to X-linked adrenoleukodystrophy and hyperoxaluria type 1.

Polymer Therapeutics: Biomarkers and New Approaches for Personalized Cancer Treatment

Polymer therapeutics (PTs) provides a potentially exciting approach for the treatment of many diseases by enhancing aqueous solubility and altering drug pharmacokinetics at both the whole organism and subcellular level leading to improved therapeutic outcomes. However, the failure of many polymer-drug conjugates in clinical trials suggests that we may need to stratify patients in order to match each patient to the right PT. In this concise review, we hope to assess potential PT-specific biomarkers for cancer treatment, with a focus on new studies, detection methods, new models and the opportunities this knowledge will bring for the development of novel PT-based anti-cancer strategies. We discuss the various "hurdles" that a given PT faces on its passage from the syringe to the tumor (and beyond), including the passage through the bloodstream, tumor targeting, tumor uptake and the intracellular release of the active agent. However, we also discuss other relevant concepts and new considerations in the field, which we hope will provide new insight into the possible applications of PT-related biomarkers.

Molecular therapy of primary hyperoxaluria

During the last few decades, the molecular understanding of the mechanisms involved in primary hyperoxalurias (PHs) has set the stage for novel therapeutic approaches. The availability of PH mouse models has facilitated preclinical studies testing innovative treatments. PHs are autosomal recessive diseases where the enzymatic deficit plays a central pathogenic role. Thus, molecular therapies aimed at restoring such deficit or limiting the consequences of the metabolic derangement could be envisioned, keeping in mind the specific challenges posed by the cell-autonomous nature of the deficiency. Various molecular approaches like enzyme replacement, substrate reduction, pharmacologic chaperones, and gene and cell therapies have been explored in cells and mouse models of disease. Some of these proof-of-concept studies have paved the way to current clinical trials on PH type 1, raising hopes that much needed treatments will become available for this severe inborn error of metabolism.