Phase I trial of p28 (NSC745104), a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in pediatric patients with recurrent or progressive central nervous system tumors: A Pediatric Brain Tumor Consortium Study.

BACKGROUND: p53 is a promising target in human cancer. p28 is a cell-penetrating peptide that preferentially enters cancer cells and binds to both wild-type and mutant p53 protein, inhibiting COP1-mediated ubiquitination and proteasomal degradation. This results in increased levels of p53, which induces cell cycle arrest at G2/M. We conducted a phase I study to determine the maximum-tolerated dose (MTD) and describe the dose-limiting toxicities (DLTs) and pharmacokinetics (PKs) of p28 in children. METHODS: Children aged 3-21 years with recurrent or progressive central nervous system tumors were eligible. Intravenous p28 was administered 3 times weekly for 4 consecutive weeks of a 6-week cycle at 4.16 mg/kg/dose (the adult recommended phase II dose) using a rolling-6 study design. Expression status of p53 was characterized by immunohistochemistry, and serum PK parameters were established on the second dose. RESULTS: Of the 18 eligible patients enrolled in the study, 12 completed the DLT monitoring period and were evaluable for toxicity. p28 was well-tolerated; 7 participants received ≥2 courses, and the most common adverse event attributed to the drug was transient grade 1 infusion-related reaction. PK analysis revealed a profile similar to adults; however, an increased area under the curve was observed in pediatric patients. High p53 expression in tumor cell nuclei was observed in 6 of 12 available tissue samples. There were no objective responses; 2 participants remained stable on the study for >4 cycles. CONCLUSIONS: This phase I study demonstrated that p28 is well-tolerated in children with recurrent CNS malignancies at the adult recommended phase II dose.

A first-in-class, first-in-human, phase I trial of p28, a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in patients with advanced solid tumours.

BACKGROUND: This first-in-human, phase I clinical trial of p28 (NSC745104), a 28-amino-acid fragment of the cupredoxin azurin, investigated the safety, tolerability, pharmacokinetics and preliminary activity of p28 in patients with p53(+) metastatic solid tumours. METHODS: A total of 15 patients were administered p28 i.v. as a short infusion three times per week for 4 weeks followed by a 2-week rest under an accelerated titration 3+3 dose escalation design until either a grade 3-related adverse event occurred or the maximum tolerated dose (MTD) was reached. Single-dose and steady-state serum pharmacokinetics were characterised. Assessments included toxicity, best objective response by RECIST 1.1 Criteria, and overall survival. RESULTS: No patients exhibited any dose-limiting toxicities (DLTs), significant adverse events or exhibited an immune response (IgG) to the peptide. The No Observed Adverse Effect Level (NOAEL) and MTD were not reached. Seven patients demonstrated stable disease for 7-61 weeks, three a partial response for 44-125 weeks, and one a complete response for 139 weeks. Three patients are still alive at 158, 140, and 110 weeks post therapy completion. CONCLUSION: p28 was tolerated with no significant adverse events. An MTD was not reached. Evidence of anti-tumour activity indicates a highly favourable therapeutic index and demonstrates proof of concept for this new class of non-HDM2-mediated peptide inhibitors of p53 ubiquitination.

Preclinical pharmacokinetics, metabolism, and toxicity of azurin-p28 (NSC745104) a peptide inhibitor of p53 ubiquitination.

PURPOSE: Characterize the preclinical pharmacokinetics, metabolic profile, multi-species toxicology, and antitumor efficacy of azurin-p28 (NSC 745104), an amphipathic, 28 amino acid fragment (aa 50-77) of the copper containing redox protein azurin that preferentially enters cancer cells and is currently under development for treatment of p53-positive solid tumors. METHODS: An LC/MS/MS assay was developed, validated, and applied to liver microsomes, serum, and tumor cells to assess cellular uptake and metabolic stability. Pharmacokinetics was established after administration of a single intravenous dose of p28 in preclinical species undergoing chronic toxicity testing. Antitumor efficacy was assessed on human tumor xenografts. A human therapeutic dose was predicted based on efficacy and pharmacokinetic parameters. RESULTS: p28 is stable, showed tumor penetration consistent with selective entry into tumor cells and significantly inhibited p53-positive tumor growth. Renal clearance, volume of distribution, and metabolic profile of p28 was relatively similar among species. p28 was non-immunogenic and non-toxic in mice and non-human primates (NHP). The no observed adverse effect level (NOAEL) was 120 mg/kg iv in female mice. A NOAEL was not established for male mice due to decreased heart and thymus weights that was reversible and did not result in limiting toxicity. In contrast, the NOAEL for p28 in NHP was defined as the highest dose (120 mg/kg/dose; 1,440 mg/m(2)/dose) studied. The maximum-tolerated dose (MTD) for subchronic administration of p28 to mice is >240 mg/kg/dose (720 mg/m(2)/dose), while the MTD for subchronic administration of p28 to Cynomolgous sp. is >120 mg/kg (1,440 mg/m(2)/dose). The efficacious (murine) dose of p28 was 10 mg/kg ip per day. CONCLUSIONS: p28 does not exhibit preclinical immunogenicity or toxicity, has a similar metabolic profile among species, and is therapeutic in xenograft models.

A novel and rapid LC/MS/MS assay for bioanalysis of Azurin p28 in serum and its pharmacokinetics in mice.

Azurin p28 (NSC745104) is a 28 amino acid peptide fragment that inhibits proliferation of human solid and hematological malignancies in vitro and in vivo by reducing proteasomal degradation of oncogene p53. The present study aimed at developing a novel and fast liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the bioanalysis of p28 in mouse serum, and determining Azurin p28 stability and pharmacokinetics in mice after full method validation. Both Azurin p28 and its internal standard MP-1 were separated and extracted from serum by using perchloric acid (7%, v/v) without time-consuming reconstitution. Chromatographic separation of Azurin p28 and MP-1 from the serum matrix was achieved using a C18 column with a gradient elution profile consisting of 5 mM ammonium acetate and acetonitrile, both containing formic acid. Mass analysis was conducted using positive ion electrospray ionization (ESI) and multiple reaction monitoring (MRM). It took 7.5 min to analyze one sample. The validated concentration range of the method extended from 100 to 10,000 ng/ml with accuracies of 85-115% and inter-day precision (CV) of <15%. Inter-day accuracy ranged from 96.4% to 103% and CV ranged from 4.61% to 6.90%. The average recovery of Azurin p28 from mouse serum at three concentrations (200, 1000, and 5000 ng/ml) was determined to be 96.4%. Incubation of Azurin p28 at 37 degrees C for 24h resulted in its degradation 55% in monkey serum, 41% in human serum, and 32-34% in mouse and dog serum. Intravenous administration of Azurin p28 to mice showed its t(1/2 beta) 0.23 h, clearance 1.7 l/kg/h, and volume of distribution at steady state 4.1l/kg. In conclusion, the novel and fast bioanalytical method was proven to be useful for pharmacokinetic profiling of Azurin p28.

Noncationic peptides obtained from azurin preferentially enter cancer cells.

Azurin, a member of the cupredoxin family of copper containing redox proteins, preferentially penetrates human cancer cells and exerts cytostatic and cytotoxic (apoptotic) effects with no apparent activity on normal cells. Amino acids 50 to 77 (p28) of azurin seem responsible for cellular penetration and at least part of the antiproliferative, proapoptotic activity of azurin against a number of solid tumor cell lines. We show by confocal microscopy and fluorescence-activated cell sorting that amino acids 50 to 67 (p18) are a minimal motif (protein transduction domain) responsible for the preferential entry of azurin into human cancer cells. A combination of inhibitors that interfere with discrete steps of the endocytotic process and antibodies for caveolae and Golgi-mediated transport revealed that these amphipathic, alpha-helical peptides are unique. Unlike the cationic cell-penetrating peptides, alpha-helical antennapedia-like, or VP22 type peptides, p18 and p28 are not bound by cell membrane glycosaminoglycans and preferentially penetrate cancer cells via endocytotic, caveosome-directed, and caveosome-independent pathways. Once internalized, p28, but not p18, inhibits cancer cell proliferation initially through a cytostatic mechanism. These observations suggest the azurin fragments, p18 and p28, account for the preferential entry of azurin into human cancer cells and a significant amount of the antiproliferative activity of azurin on human cancer cells, respectively.

Histochemical staining of bone aluminum: comparison of aluminon and acid solochrome azurine and their correlation with bone aluminum content

O aluminio (Al) pode ser um dos fatores patogenicos envolvidos na doença ossea de pacientes uremicos. Os corantes Aluminon (Acido Tricarboxilico aurico) e Acido Solocromo Azurina, tem sido utilizados para detectar depositos de aluminio no tecido osseo. Utilizamos um modelo experimental de intoxicaçäo aluminica em ratos normais (N) e uremicos (U) e comparamos a sensibilidade dos dois corantes na detecçäo do aluminio. Os grupos receberam injeçöes intraperitoniais de Cloreto de Aluminio (AlCl3), ate uma dose cumulativa de 5 mg (NAL5; UAL5) e 30 mg (NAL30; UAL30). Os grupos controles receberam injeçöes intraperitoniais de agua destilada...