ITPA polymorphisms do not predict additional risk beyond TPMT and NUDT15 for thiopurine-induced cytopenia in inflammatory bowel disease

INTRODUCTION AND AIM

Thiopurine-related leukopenia is associated with polymorphisms in the thiopurine methyltransferase (TPMT) and nucleoside diphosphate-linked moiety X type motif 15 (NUDT15) genes. However, those polymorphisms explain only a fraction of thiopurine-related leukopenia. Our aim was to study the role of an inosine triphosphate pyrophosphatase (ITPA) polymorphism in patients with inflammatory bowel disease (IBD) and thiopurine-related leukopenia that was unexplained by the TPMT and NUDT15 polymorphisms.

MATERIAL AND METHODS

We enrolled consecutive IBD patients on thiopurines (azathioprine or 6-mercaptopurine) from January 2019-March 2020, at a tertiary care center in North India. The presence of the ITPA (C.94C > A) polymorphism was evaluated in all patients, along with its association with thiopurine-related leukopenia.

RESULTS

Of the 33 patients (from a total of 119 patients) that developed leukopenia, 8 had the TPMT (n = 1) or NUDT15 (n = 7) polymorphism. Of the remaining 111 patients, their mean age was 36.36 ± 13.54 years and 57 (51.3%) were males. Twenty-five (21.01%) had unexplained leukopenia. The ITPA polymorphism was detected in 4 (16%) patients in the unexplained leukopenia group and 24 (27.9%) patients in the non-leukopenia group (p = 0.228). The odds ratio for predicting leukopenia with the ITPA polymorphism was 0.4921 (95% CI 0.1520-1.5830, p = 0.234).

CONCLUSION

The ITPA (C.94C > A) polymorphism was frequently detected in the study population but was not predictive for leukopenia in patients with IBD on thiopurine therapy.

Effect of Urate-Elevating Inosine on Early Parkinson Disease Progression: The SURE-PD3 Randomized Clinical Trial

Importance

Urate elevation, despite associations with crystallopathic, cardiovascular, and metabolic disorders, has been pursued as a potential disease-modifying strategy for Parkinson disease (PD) based on convergent biological, epidemiological, and clinical data.

Objective

To determine whether sustained urate-elevating treatment with the urate precursor inosine slows early PD progression.

Design, Participants, and Setting

Randomized, double-blind, placebo-controlled, phase 3 trial of oral inosine treatment in early PD. A total of 587 individuals consented, and 298 with PD not yet requiring dopaminergic medication, striatal dopamine transporter deficiency, and serum urate below the population median concentration (<5.8 mg/dL) were randomized between August 2016 and December 2017 at 58 US sites, and were followed up through June 2019.

Interventions

Inosine, dosed by blinded titration to increase serum urate concentrations to 7.1-8.0 mg/dL (n = 149) or matching placebo (n = 149) for up to 2 years.

Main Outcomes and Measures

The primary outcome was rate of change in the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS; parts I-III) total score (range, 0-236; higher scores indicate greater disability; minimum clinically important difference of 6.3 points) prior to dopaminergic drug therapy initiation. Secondary outcomes included serum urate to measure target engagement, adverse events to measure safety, and 29 efficacy measures of disability, quality of life, cognition, mood, autonomic function, and striatal dopamine transporter binding as a biomarker of neuronal integrity.

Results

Based on a prespecified interim futility analysis, the study closed early, with 273 (92%) of the randomized participants (49% women; mean age, 63 years) completing the study. Clinical progression rates were not significantly different between participants randomized to inosine (MDS-UPDRS score, 11.1 [95% CI, 9.7-12.6] points per year) and placebo (MDS-UPDRS score, 9.9 [95% CI, 8.4-11.3] points per year; difference, 1.26 [95% CI, -0.59 to 3.11] points per year; P = .18). Sustained elevation of serum urate by 2.03 mg/dL (from a baseline level of 4.6 mg/dL; 44% increase) occurred in the inosine group vs a 0.01-mg/dL change in serum urate in the placebo group (difference, 2.02 mg/dL [95% CI, 1.85-2.19 mg/dL]; P<.001). There were no significant differences for secondary efficacy outcomes including dopamine transporter binding loss. Participants randomized to inosine, compared with placebo, experienced fewer serious adverse events (7.4 vs 13.1 per 100 patient-years) but more kidney stones (7.0 vs 1.4 stones per 100 patient-years).

Conclusions and Relevance

Among patients recently diagnosed as having PD, treatment with inosine, compared with placebo, did not result in a significant difference in the rate of clinical disease progression. The findings do not support the use of inosine as a treatment for early PD.

Trial Registration

ClinicalTrials.gov Identifier: NCT02642393.

Improved Parkinsons disease motor score in a single-arm open-label trial of febuxostat and inosine

BACKGROUND

Cellular energetics play an important role in Parkinsons disease etiology, but no treatments directly address this deficiency. Our past research showed that treatment with febuxostat and inosine increased blood hypoxanthine and ATP in healthy adults, and a preliminary trial in 3 Parkinson's disease patients suggested some symptomatic improvements with no adverse effects.

METHODS

To examine the efficacy on symptoms and safety in a larger group of Parkinsons disease patients, we conducted a single-arm, open-label trial at 5 Japanese neurology clinics and enrolled thirty patients (nmales = 11; nfemales = 19); 26 patients completed the study (nmales = 10; nfemales = 16). Each patient was administered febuxostat 20 mg and inosine 500 mg twice-per-day (after breakfast and dinner) for 8 weeks. The primary endpoint was the difference of MDS-UPDRS Part III score immediately before and after 57 days of treatment.

RESULTS

Serum hypoxanthine concentrations were raised significantly after treatment (Pre = 11.4 μM; Post = 38.1 μM; P < .0001). MDS-UPDRS Part III score was significantly lower after treatment (Pre = 28.1 ± 9.3; Post = 24.7 ± 10.8; mean ± SD; P = .0146). Sixteen adverse events occurred in 13/29 (44.8%) patients, including 1 serious adverse event (fracture of the second lumbar vertebra) that was considered not related to the treatment.

CONCLUSIONS

The results of this study suggest that co-administration of febuxostat and inosine is relatively safe and effective for improving symptoms of Parkinsons disease patients. Further controlled trials need to be performed to confirm the symptomatic improvement and to examine the disease-modifying effect in long-term trials.

Screening and characterization of purine nucleoside degrading lactic acid bacteria isolated from Chinese sauerkraut and evaluation of the serum uric acid lowering effect in hyperuricemic rats

Hyperuricemia is well known as the cause of gout. In recent years, it has also been recognized as a risk factor for arteriosclerosis, cerebrovascular and cardiovascular diseases, and nephropathy in diabetic patients. Foods high in purine compounds are more potent in exacerbating hyperuricemia. Therefore, the development of probiotics that efficiently degrade purine compounds is a promising potential therapy for the prevention of hyperuricemia. In this study, fifty-five lactic acid bacteria isolated from Chinese sauerkraut were evaluated for the ability to degrade inosine and guanosine, the two key intermediates in purine metabolism. After a preliminary screening based on HPLC, three candidate strains with the highest nucleoside degrading rates were selected for further characterization. The tested biological characteristics of candidate strains included acid tolerance, bile tolerance, anti-pathogenic bacteria activity, cell adhesion ability, resistance to antibiotics and the ability to produce hydrogen peroxide. Among the selected strains, DM9218 showed the best probiotic potential compared with other strains despite its poor bile resistance. Analysis of 16S rRNA sequences showed that DM9218 has the highest similarity (99%) to Lactobacillus plantarum WCFS1. The acclimated strain DM9218-A showed better resistance to 0.3% bile salt, and its survival in gastrointestinal tract of rats was proven by PCR-DGGE. Furthermore, the effects of DM9218-A in a hyperuricemia rat model were evaluated. The level of serum uric acid in hyperuricemic rat can be efficiently reduced by the intragastric administration of DM9218-A (P<0.05). The preventive treatment of DM9218-A caused a greater reduction in serum uric acid concentration in hyperuricemic rats than the later treatment (P<0.05). Our results suggest that DM9218-A may be a promising candidate as an adjunctive treatment in patients with hyperuricemia during the onset period of disease. DM9218-A also has potential as a probiotic in the prevention of hyperuricemia in the normal population.

Effect of oxidative stress on expression and function of human and rat organic anion transporting polypeptides in the liver

Reactive oxygen species (ROS) have physiological function and involve alteration of physical state. However, it is not clear effect of oxidative stress on pharmacokinetics. Organic anion transporting polypeptides (human: OATPs, rodent: Oatps) are important for uptake of endogenous and exogenous compounds into hepatocytes. Thus, alteration of OATPs/Oatps expression level may affect pharmacokinetics of various drugs. In this study, we investigated the alteration of OATPs/Oatps expression levels and function by oxidative stress, and the effect of alteration of those on pharmacokinetics of a typical OATPs/Oatps substrate pravastatin. OATPs/Oatps expression levels and function were altered by H2O2-induced oxidative stress in in vitro experiments. The alteration of Oatps expression by oxidative stress also occurred in in vivo experiments. Oatp1a1, Oatp1a4 and Oatp1b2 expression in the liver were decreased in rats fed powdery diet containing 2% inosine, which induces oxidative stress through activation of xanthine oxidase, for 1 day. The decrease in Oatps expression levels by oxidative stress caused the suppression of pravastatin uptake to the liver, and resulted in high plasma concentration of pravastatin and low biliary excretion. In conclusion, oxidative stress induces alteration of OATPs/Oatps expression and function in hepatocytes, resulting in alteration of pharmacokinetics of their substrates.

The treatment of multiple sclerosis with inosine

OBJECTIVE

The objective of this study is to evaluate the safety and tolerability of inosine in patients with relapsing-remitting multiple sclerosis (RRMS). The secondary objectives are to assess the effects of inosine administration on serum urate (UA) levels, the progression of neurologic disability, the cumulative number of new, active lesions on magnetic resonance imaging (MRI), and changes in serum levels for markers of inflammation.

DESIGN

Oral administration of inosine was used to raise serum levels of the natural peroxynitrite scavenger UA in 16 patients with RRMS during a 1-year randomized, double-blind trial.

OUTCOME MEASURES

The endpoints studied were relapse rate, disability assessed by the Kurtzke Expanded Disability Status Scale (EDSS), MRI, and analysis of serum levels of nitrotyrosine, and oxidative and pro-inflammatory makers.

RESULTS

Increased serum UA levels correlated with a significant decrease in the number of gadolinium-enhanced lesions and improved EDSS. A number of MRI intensity-based parameters were altered by inosine treatment, in certain cases correlating with changes in serum UA levels. In a patient with low serum UA and high lesion activity, raising UA levels by inosine treatment decreased serum nitrotyrosine while increasing the ratio of Th2 to Th1 cytokines in circulating cells. The only side-effect correlated with inosine treatment was kidney stone formation in 4/16 subjects.

CONCLUSIONS

These data suggest that the use of inosine to raise serum UA levels may have benefits for at least some MS patients. The effect of this treatment is likely to be a consequence of inactivation of peroxynitrite-dependent free radicals. Close monitoring of serum UA levels as well as other measures are required to avoid the potential development of kidney stones.

[Evaluation for two-year highly active antiretroviral therapy in Chinese HIV-1 infection patients]

OBJECTIVE

To observe that antiretroviral efficacy, immune reconstitution of two-year HAART, and evaluate its side effect in Chinese HIV-1-infected patients.

METHODS

Three drug regimen composed of didanosine (ddI), stavudine (d4T), and nevirapine (NVP) was used on 27 HIV-1 infected patients, Within 2 weeks before treatment, and 3, 6, 12, 18, and 24 months after the beginning of treatment peripheral blood samples were collected to measure the HIV-RNA viral load (VL) by fluorescent quantitative polymerase chain reactions (FQ-PCR), and the counts of CD3+CD4+ cells, CD3+CD8+ cells, CD4+CD45RA+CD62L+ cells, CD4+CD45RO+ cells, CD8+CD38+ cells, and CD8+CD38+/CD3+CD8+ percentage. The side effects, blood routine, main biochemical parameters, and other disadvantageous accidents were monitored during the 24-mouth treatment period. 17 males and 10 females, aged 33 +/- 11. Thirty-one sex- and age-matched healthy persons were used as controls.

RESULTS

FQ-PCR showed that the plasma HIV-1 RNA levels 2 weeks before treatment, and 3, 6, 12, 18, and 24 months after the beginning of treatment were 5.15 logs (copies/ml), 3.37 logs, 2.24 logs, 2.02 logs, 1.97 logs, and 2.15 logs respectively. 24 months after the treatment. In 56.6% (13/24) of the patients the HIV-1 VL was < 50 copies/ml 24 months after treatment, and the counts of CD3+CD4+ cells, CD4+CD45RA+62L+ cells (nave cells), and CD4+CD45RO+ cells (memory cells) 24 months after treatment were (317 +/- 175) cells/microl, (133 +/- 65) cells/microl, and (207 +/- 85) cells/microl respectively, all significantly hoi/higher than the baseline levels [(185 +/- 73) cells/microl, (51 +/- 21) cells/microl, and (115 +/- 57) cells/microl respectively]. And the CD3+CD8+ cell count, CD8+CD38+ cell count, and CD8+CD38+/CD3+CD8+ percentage decreased from (907 +/- 435) cells/microl, (614 +/- 299) cells/microl, and 67.7% to (775 +/- 303) cells/microl, (385 +/- 131) cells/microl, and 49.7% respectively, with the lowest values in the months 3 and 6. But by the month 24, all of the parameters failed to reach the normal level. 19 of the 27 patients had side effects, such as peripheral polyneuropathy, various rashes, central nervous system disorders, abdominal pain, fullness or bloating, fever, and baldness, 21 showed abnormalities in blood routine, liver function, renal function, or lipid tests and increased gamma glutamyl transferase (GGT) and amylase. The regimen had to be changed for 3 of these patients because of paresthesia and suspected lactic acidosis.

CONCLUSION

The regimen with ddI, d4T and NVP foe 24 months showed a good antiretroviral effect and immune reconstitution on the HIV-1 infected persons. However, there are side effects, especially in the respect of gastrointestinal disorder and peripheral neuritis, decrease of WBC and increase of GGT and amylase.

[Papules on the dorsal interphalangeal joints and an unspecific immunostimulating agent]

We report the case of an 8-year-old girl with skin eruptions on both hands that were thought to be of viral origin and, therefore, had been treated with an unspecific immunostimulating agent, containing large amounts of inosine. Under this therapy, which is - despite contrasting knowledge - still thought to be harmless and without serious side effects in the opinion of many physicians and especially medical laymen, the girl's condition worsened rapidly. Diagnosis of juvenile dermatomyositis was made. Because inosine is able to enhance T-cell proliferation and reverse immunosuppression in vitro, both mechanisms may have aggravated the disease course in our patient, once the autoimmune process of dermatomyositis has been initiated.

[Pharmacological agents affecting uric acid metabolism]

A large number of pharmacological agents affect the serum concentration of uric acid. Some drugs raise serum uric acid level by an increase in uric acid production or a decrease in uric acid excretion, while others lower serum uric acid level by a decrease in uric acid production or an increase in uric acid excretion. In addition, some drugs show so-called biphasic effect; ie, hyperuricemic in lower doses but hypouricemic in higher doses. Hyperuricemic agents contribute to gout and/or urate nephropathy. Among them, pyrazinamide is often used to determine the defective site(s) of uric acid transport in renal tubules in conjunction with uricosuric agents, such as benzbromarone or probenecid. In contrast, the clinical significance of hypouricemic agents other than uricosuric agents has not been emphasized. However, some may induce acute uric acid nephropathy by a significant increase in uric acid excretion. In this review, drugs affecting uric acid metabolism are summarized with regard to their mechanism of action and clinical significance.

Intravenous infusion of adenosine but not inosine stimulates respiration in man

The effects on respiration of intravenous infusions of the endogenous nucleoside adenosine and its deaminated metabolite, inosine, administered in random order, single-blind, were compared in six healthy volunteers. The infusion rate of each nucleoside was initially 3.1 mg min-1 and was increased stepwise every 2 min, as tolerated, up to a possible maximum of 23.4 mg ml-1. The maximum dose rates received by all subjects were 8.5 mg min-1 for adenosine and 16.8 mg min-1 for inosine. Adenosine infusion at rates of 6.1 mg min-1 and above caused a significant increase in minute ventilation, principally due to an increase in tidal volume, with an associated significant fall in end-tidal Pco2. Mean inspiratory flow rate increased and expiratory duration decreased during adenosine infusion, but there was no change in inspiratory duration. Adenosine infusion also caused a significant increase in heart rate and a slight, but significant increase in systolic blood pressure. Infusion of inosine at dose rates up to 16.8 mg min-1 produced no pharmacological effects. This study shows that adenosine by infusion produces sustained respiratory stimulation in man and demonstrates that it does not depend on prior conversion of adenosine to inosine or related metabolites and that it is not secondary to systemic hypotension.

Phase II study of diglycoaldehyde in malignant melanomas and soft tissue sarcomas

A phase II study of diglycoaldehyde was conducted in 42 patients with malignant melanoma and soft tissue sarcoma. All patients received diglycoaldehyde at a dose of 2 g/m2 iv over 6 hours daily for 3 days. This was repeated every 28 days. Major toxic effects included phlebitis and azotemia, requiring dialysis in one patient. Of the 42 patients, 38 were evaluable for response. One objective response occurred in a patient with malignant melanoma. Diglycoaldehyde at this dose and schedule appears to have no role in the management of malignant melanoma or soft tissue sarcoma.

Overadditive chemotherapeutic synergism of prospidine and inosine when given sequentially to the Sarcoma 180 implanted intramuscularly

The chemotherapeutic effectiveness of prospidine monotherapy on the Sarcoma 180 implanted i.m. was compared with several prospidine/inosine combinations. The chemotherapeutic action of the combination was enhanced overadditively when inosine was given 6 h after prospidine. This particular combination caused not only a significant curative action and tumor inhibition as compared with prospidine monotherapy, but also decreased the toxic effects.

Clinical phase I trial of inosine dialdehyde (NSC-118994)

An initial clinical phase I trial of inosine dialdehyde has been carried out in 40 patients at dose levels of 30-4000 mg/m2 for 5 days given intravenously (iv) monthly. At 1.5 g/m2, noncumulative dose-related toxicity occurred in all patients which consisted of nausea and vomiting, local pain, alterations in coagulation mechanism, elevated partial thromboplastin time, and positive Coombs' test. No dose-limiting leukopenia, thrombocytopenia, anemia, or bleeding occurred; however, depression of the leukocyte and platelet counts, and decreased hemoglobin value were observed. The dose-limiting toxic effect was renal tubular damage with reversible acute renal failure in one of four patients who received 3000 mg/m2 iv for 5 days. Refractory hypercalcemia was controlled in three of three patients without tumor effect. Responses occurred in patients with seminoma, oat cell carcinoma, and melanoma. A starting dose of 2 g/m2 for 3 days monthly is recommended for phase II trials and a trial in lung carcinoma is now being conducted.

[Influence of ribose on 2,3-diphosphoglycerate concentrations in human erythrocytes]

The effect of ribose on the 2,3-diphosphoglycerate concentration (2,3-DPG) of human red blood cells was investigated and compared to the effect of inosine. Ribose as well as inosine increases 2,3-DPG. Most impressing effects can be demonstrated on stored blood, which is poor in 2,3-DPG concentration. Physiologic 2,3-DPG-concentrations, however, may be increased too. Generally the effect of inosine is greater than the effect of ribose. When ribose is applicated intravenously a slight increase in 2,3-DPG is found. Both compounds own characteristic side-effects, which diminish their value for therapeutical purposes.