Assessment of pegylated arginine deiminase and modified FOLFOX6 in patients with advanced hepatocellular carcinoma: Results of an international, single-arm, phase 2 study

From the Inside Out: Exposing the Roles of Urea Cycle Enzymes in Tumors and Their Micro and Macro Environments

Catabolic pathways change in anabolic diseases such as cancer to maintain metabolic homeostasis. The liver urea cycle (UC) is the main catabolic pathway for disposing excess nitrogen. Outside the liver, the UC enzymes are differentially expressed based on each tissue's needs for UC intermediates. In tumors, there are changes in the expression of UC enzymes selected for promoting tumorigenesis by increasing the availability of essential UC substrates and products. Consequently, there are compensatory changes in the expression of UC enzymes in the cells that compose the tumor microenvironment. Moreover, extrahepatic tumors induce changes in the expression of the liver UC, which contribute to the systemic manifestations of cancer, such as weight loss. Here, we review the multilayer changes in the expression of UC enzymes throughout carcinogenesis. Understanding the changes in UC expression in the tumor and its micro and macro environment can help identify biomarkers for early cancer diagnosis and vulnerabilities that can be targeted for therapy.

Combined FOLFOX4 with all-trans retinoic acid versus FOLFOX4 with placebo in treatment of advanced hepatocellular carcinoma with extrahepatic metastasis: a randomized, double-blind comparative study

The majority of hepatocellular carcinoma (HCC) cases are diagnosed at an advanced stage. Currently, there are only a few therapeutic methods available for patients with advanced HCC and extrahepatic metastasis (EHM). Systemic chemotherapy, such as FOLFOX4 (infusions of fluorouracil, leucovorin, and oxaliplatin), has been reported for treating advanced HCC with EHM, but its effectiveness is very poor. In this randomized, double-blind, placebo-controlled study, we aimed to assess the efficacy and safety of FOLFOX4 with all-trans-retinoic acid (ATRA) as a palliative treatment for HCC patients with EHM, compared to FOLFOX4 with a placebo. The primary endpoint was overall survival (OS), and subsequently, an exploratory model was developed based on bioinformatics to predict the efficacy of FOLFOX4-ATRA treatment. A total of 108 patients were randomly assigned in a 1:1 ratio to receive either FOLFOX4-ATRA or FOLFOX4-placebo. The intention-to-treat (ITT) population showed a median OS of 16.2 months for the FOLFOX4-ATRA group, compared with 10.7 months for the FOLFOX4-placebo group (HR 0.56, 95% CI 0.33-0.93; p = 0.025). The median progression-free survival (PFS) was 7.1 months for the FOLFOX4-ATRA group and 4.2 months for the FOLFOX4-placebo group (HR 0.62, 95% CI 0.41-0.94; p = 0.024). A panel of proteins with unique upregulation during complete response (CR) (SOD3, TTR, SSC5D, GP5, IGKV1D-33) and partial response (PR) (TGFB1, GSS, IGHV5-10-1) effectively predicted CR and PR in patients treated with FOLFOX4-ATRA, as compared to FOLFOX4-placebo. The results suggest that FOLFOX4-ATRA is a safe and effective treatment for patients with advanced HCC and EHM in eastern China.

Arginine regulates HSPA5/BiP translation through ribosome pausing in triple-negative breast cancer cells

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a high mortality rate due to a lack of therapeutic targets. Many TNBC cells are reliant on extracellular arginine for survival and express high levels of binding immunoglobin protein (BiP), a marker of metastasis and endoplasmic reticulum (ER) stress response.

METHODS

In this study, the effect of arginine shortage on BiP expression in the TNBC cell line MDA-MB-231 was evaluated. Two stable cell lines were generated in MDA-MB-231 cells: the first expressed wild-type BiP, and the second expressed a mutated BiP free of the two arginine pause-site codons, CCU and CGU, termed G-BiP.

RESULTS

The results showed that arginine shortage induced a non-canonical ER stress response by inhibiting BiP translation via ribosome pausing. Overexpression of G-BiP in MDA-MB-231 cells promoted cell resistance to arginine shortage compared to cells overexpressing wild-type BiP. Additionally, limiting arginine led to decreased levels of the spliced XBP1 in the G-BiP overexpressing cells, potentially contributing to their improved survival compared to the parental WT BiP overexpressing cells.

CONCLUSION

In conclusion, these findings suggest that the downregulation of BiP disrupts proteostasis during arginine shortage-induced non-canonical ER stress and plays a key role in cell growth inhibition, indicating BiP as a target of codon-specific ribosome pausing upon arginine shortage.

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.

WWOX-rs13338697 genotype predicts therapeutic efficacy of ADI-PEG 20 for patients with advanced hepatocellular carcinoma

BACKGROUND

Previous studies have identified three single nucleotide polymorphisms (SNPs): GALNT14-rs9679162, WWOX-rs13338697 and rs6025211. Their genotypes are associated with therapeutic outcomes in hepatocellular carcinoma (HCC). Herein, we examined whether these SNP genotypes could predict the clinical outcome of HCC patients treated with ADI-PEG 20.

METHODS

Totally 160 patients with advanced HCC, who had previously been enrolled in clinical trials, including 113 receiving ADI-PEG 20 monotherapy (cohort-1) and 47 receiving FOLFOX/ADI-PEG 20 combination treatment (cohort-2), were included retrospectively.

RESULTS

The WWOX-rs13338697-GG genotype was associated with favorable overall survival in cohort-1 patients (P = 0.025), whereas the rs6025211-TT genotype was associated with unfavorable time-to-tumor progression in cohort-1 (P = 0.021) and cohort-1 plus 2 patients (P = 0.008). As ADI-PEG 20 can reduce plasma arginine levels, we examined its pretreatment levels in relation to the WWOX-rs13338697 genotypes. Pretreatment plasma arginine levels were found to be significantly higher in patients carrying the WWOX-rs13338697-GG genotype (P = 0.006). We next examined the association of the WWOX-rs13338697 genotypes with WWOX tissue protein levels in 214 paired (cancerous/noncancerous) surgically resected HCC tissues (cohort-3). The WWOX-rs13338697-GG genotype was associated with decreased tissue levels of WWOX and ASS1. Mechanistic studies showed that WWOX and ASS1 levels were downregulated in hypoxic HCC cells. Silencing WWOX to mimic low WWOX protein expression in HCC in patients with the WWOX-rs13338697-GG genotype, enhanced HIF1A increment under hypoxia, further decreased ASS1, and increased cell susceptibility to ADI-PEG 20.

COMCLUSION

In summary, the WWOX-rs13338697 and rs6025211 genotypes predicted treatment outcomes in ADI-PEG 20-treated advanced HCC patients. The WWOX-rs13338697-GG genotype was associated with lower tissue WWOX and ASS1 levels and higher pretreatment plasma arginine levels, resembling an arginine auxotrophic phenotype requires excessive extracellular arginine supply. Silencing WWOX to mimic HCC with the WWOX-rs13338697-GG genotype further stimulated HCC cell response to hypoxia through increased HIF1A expression, leading to further reduction of ASS1 and thus increased cell susceptibility to ADI-PEG 20.

Experimental drug treatments for hepatocellular carcinoma: Clinical trial failures 2015 to 2021

INTRODUCTION

Hepatocellular carcinoma (HCC) is a major health problem worldwide with limited systemic therapy options. Since the approval of sorafenib in 2008, no systemic therapy has provided a sustained/robust/survival benefit for patients with advanced HCC until recently. Many initially promising therapies have been trialed, but survival outcomes remained stagnant. As such, knowledge concerning previous treatment failures may help guide further areas of study, as well inform future therapeutic approaches.

AREA COVERED

This article reviews recent advances in the treatment of HCC. Despite some recent success, many systemic and locoregional therapies have failed to produce significant improvements in outcome. These treatment failures are examined and insight into pathways for future success are discussed.

EXPERT OPINION

Combination atezolizumab and bevacizumab has changed the landscape of systemic treatment for patients with HCC when it became the first therapy after demonstrating improve outcomes over sorafenib. Clinical trials in patients with advanced HCC have inherent difficulty with challenges to determine if a patient's declining liver function is secondary to disease progression, worsening cirrhosis, or drug toxicity, which may skew results. As we gain more knowledge of underlying genetic alterations behind the pathophysiology of the development of HCC, molecular markers may be identified to assist in predicting which patients would respond to a specific therapy.

Is this as good as it gets? Implications of an asymptotic mortality decline and approaching the nadir in pediatric intensive care

Despite advances in medicine, some children will always die; a decline in pediatric intensive care unit (PICU) mortality to zero will never be achieved. The mortality decline is correspondingly asymptotic, yet we remain preoccupied with mortality outcomes. Are we at the nadir, and are we, thus, as good as we can get? And what should we focus to benchmark our units, if not mortality? In the face of changing case-mix and rising complexity, dramatic reductions in PICU mortality have been observed globally. At the same time, survivors have increasing disability, and deaths are often characterized by intensive life-sustaining therapies preceded by prolonged admissions, emphasizing the need to consider alternate outcome measures to evaluate our successes and failures. What are the costs and implications of reaching this nadir in mortality outcomes? We highlight the failings of our fixation with survival and an imperative to consider alternative outcomes in our PICUs, including the costs for both patients that survive and die, their families, healthcare providers, and society including perspectives in low resource settings. We describe the implications for benchmarking, research, and training the next generation of providers.Conlusion: Although survival remains a highly relevant metric, as PICUs continue to strive for clinical excellence, pushing boundaries in research and innovation, with endeavors in safety, quality, and high-reliability systems, we must prioritize outcomes beyond mortality, evaluate "costs" beyond economics, and find novel ways to improve the care we provide to all of our pediatric patients and their families. What is Known: • The fall in PICU mortality is asymptotic, and a decline to zero is not achievable. Approaching the nadir, we challenge readers to consider implications of focusing on medical and technological advances with survival as the sole outcome of interest. What is New: • Our fixation with survival has costs for patients, families, staff, and society. In the changing PICU landscape, we advocate to pivot towards alternate outcome metrics. • By considering the implications for benchmarking, research, and training, we may better care for patients and families, educate trainees, and expand what it means to succeed in the PICU.

PEGylation increases antitumoral activity of arginine deiminase of Streptococcus pyogenes

Abstract

Arginine auxotrophy is a metabolic defect that renders tumor cells vulnerable towards arginine-depleting substances, such as arginine deiminase (ADI) from Streptococcus pyogenes (SpyADI). Previously, we confirmed SpyADI susceptibility on patient-derived glioblastoma multiforme (GBM) models in vitro and in vivo. For application in patients, serum half-life of the enzyme has to be increased and immunogenicity needs to be reduced. For this purpose, we conjugated the S. pyogenes-derived SpyADI with 20 kDa polyethylene glycol (PEG20) moieties, achieving a PEGylation of seven to eight of the 26 accessible primary amines of the SpyADI. The PEGylation reduced the overall activity of the enzyme by about 50% without affecting the Michaelis constant for arginine. PEGylation did not increase serum stability of SpyADI in vitro, but led to a longer-lasting reduction of plasma arginine levels in mice. Furthermore, SpyADI-PEG20 showed a higher antitumoral capacity towards GBM cells in vitro than the native enzyme.

Key points

• PEGylation has no effect on the affinity of SpyADI for arginine

• PEGylation increases the antitumoral effects of SpyADI on GBM in vitro

• PEGylation prolongs plasma arginine depletion by SpyADI in mice