Biological Activity of a Thiobarbituric Acid Compound in Neuroblastomas.

BACKGROUND/AIM: We have previously reported the identification of the cytotoxic chemotype compound-I (CC-I) from a chemical library screening against glioblastoma. MATERIALS AND METHODS: The biological activity of CC-I on drug-resistant neuroblastomas [e.g., HFE gene variant C282Y stably transfected human neuroblastoma SH-SY5Y cells (C282Y HFE/SH-SY5Y), SK-N-AS] was characterized using cell culture models and in vivo mouse tumor models. RESULTS: CC-I had potent cytotoxicity on therapy-resistant neuroblastoma cells and limited cytotoxicity on human primary dermal fibroblast cells. In addition, CC-I showed a robust anti-tumor effect on therapy-resistant human neuroblastoma C282Y HFE/SH-SY5Y cells but not on SK-N-AS cells in a subcutaneous tumor model. CC-I induced phosphorylation of heat shock protein 27 (HSP27), protein kinase B (Akt), and c-Jun N-terminal kinase (JNK) in C282Y HFE/SH-SY5Y neuroblastoma cells. CONCLUSION: CC-I may be an effective therapeutic option for therapy-resistant neuroblastomas, especially if they express the C282Y HFE gene variant. Its anti-tumor effects are possibly through HSP27-Akt-JNK activation.

Characterization of a Novel Barbituric Acid and Two Thiobarbituric Acid Compounds for Lung Cancer Treatment.

BACKGROUND/AIM: Previously, we reported the identification of a cytotoxic chemotype compound CC-I (1a), a derivative of thiobarbituric acid. We also reported the anticancer activity of a series of novel thio- and seleno-barbituric acid analogs. MATERIALS AND METHODS: We herein evaluated the effect of 1a and its modified compounds on in vitro and in vivo lung cancer models. RESULTS: The compounds 1b and 2a showed more potent cytotoxicity than 1a to lung cancer cells. Moreover, 1b did not have any cytotoxicity on normal cells, such as fibroblasts. In the human lung cancer A549 mouse tumor xenograft model, 1b and 2a showed more pronounced antitumor effects than 1a In the A549 lung cancer cells, 1a induced cell death mainly via JNK and p38 MAPK activation. However, compound 1b and 2a induced lung cancer cell death mostly through JNK activation. CONCLUSION: The results suggest that 1b and 2a can be useful therapeutic agents for lung cancer.

Discovery and biological evaluation of thiobarbituric derivatives as potent p300/CBP inhibitors.

Histone acetyltransferases (HATs) relieve transcriptional repression by preferentially acetylation of ε-amino group of lysine residues on histones. Dysregulation of HATs is strongly correlated with etiology of several diseases especially cancer, thus highlighting the utmost significance of the development of small molecule inhibitors against this potential therapeutic target. In the present study, through virtual screening and iterative optimization, we identified DCH36_06 as a bona fide, potent p300/CBP inhibitor. DCH36_06 mediated p300/CBP inhibition leading to hypoacetylation on H3K18 in leukemic cells. The suppression of p300/CBP activity retarded cell proliferation in several leukemic cell lines. In addition, DCH36_06 arrested cell cycle at G1 phase and induced apoptosis via activation of capase3, caspase9 and PARP that elucidated the molecular mechanism of its anti-proliferation activity. In transcriptome analysis, DCH36_06 altered downstream gene expression and apoptotic pathways-related genes verified by real-time PCR. Importantly, DCH36_06 blocked the leukemic xenograft growth in mice supporting its potential for in vivo use that underlies the therapeutic potential for p300/CBP inhibitors in clinical translation. Taken together, our findings suggest that DCH36_06 may serve as a qualified chemical tool to decode the acetylome code and open up new opportunities for clinical intervention.

Neuroprotective and anti-inflammatory properties of a novel non-thiazolidinedione PPARγ agonist in vitro and in MPTP-treated mice.

Peroxisome proliferator-activated receptor (PPAR)γ is a potential pharmacological target for disease-modification in Parkinson's disease (PD), mainly acting by modulating the neuroinflammatory response. However, currently available agonists thiazolidinediones (TZDs) present limitations due to safety concerns. We evaluated a novel thiobarbituric-like compound MDG548, which acts as a functional PPARγ agonist displaying higher and selective binding affinity as compared to TZDs. Neuroprotection by MDG548 was tested in vitro and in a mouse MPTP model of PD, and neuroinflammation was investigated as a putative underlying mechanism. Viability assay on rat cortical neurons showed lack of cytotoxic effect in the dose-range of 100 nM-10 µM, which was therefore used for testing in vitro protection against H2O2 and MPP+ neurotoxicity. MDG548 dose-dependently increased cell viability of rat cortical neurons co-treated with H2O2 or pre-exposed to MDG548 prior to H2O2. Moreover, MDG548 induced neuroprotection in MPP+-treated PC12 cells. NF-kB activation was investigated to assess anti-inflammatory activity. MDG548 dose-dependently decreased NF-kB activation induced by LPS (100 ng/100ml) in HEK-Blue-hTLR4 cells. Given the supposed cancer risk of other PPARγ agonists, Ames test for genotoxicity was performed in Salmonella typhimurium TA100 and TA98 strains, showing that MDG548 was not genotoxic. In vivo, BL/6J mice were treated with MPTP (20mg/kg i.p. once/day for 4 days) in association with saline or MDG548 (2, 5, 10 mg/kg i.p.). Stereological counting showed that MDG548 prevented the MPTP-induced reduction in TH-positive cells in the substantia nigra compacta (SNc) at all doses tested. Moreover, MDG548 reduced reactive microglia and iNOS induction in the SNc. MDG548, being a non-TZD compound with high PPARγ affinity, void of genotoxicity, and with in vitro as well as in vivo neuroprotective properties, provides a promising alternative in the search for safer PPARγ agonists to be tested as potential disease-modifying drugs in PD.

[Isothiorbamin possesses stress-protective action]. / Izotiorbamin obladaet stressprotektivnym deistviem.

It was shown on a model of long-term stress induced by chronic electrostimulation of the ventromedial hypothalamus of rabbits that administration of isothiorbamin in the active periods of the experiment prevents hyperactivation of lipid peroxidation in the blood and myocardium by maintaining the activity of antioxidant enzymes. Isothiorbamin also causes an antiatherogenic effect on the blood lipid spectrum, raises the efficacy of the work of the heart and decreases the stressogenic ischemic disorders of the myocardium.

Phase II trial of merbarone in patients with malignant brain tumors.

The standard treatment for patients with primary malignant glioma includes surgical resection, radiotherapy, and nitrosourea. Despite this multimodality approach, adults with newly diagnosed glioblastoma multiforme (GBM) and high-grade astrocytoma have a median survival duration of 50 weeks and 150 weeks respectively. Chemotherapy has had a limited impact on the survival of these patients. Merbarone (5-phenylcarboxamide-2-thiobarbituric acid) is a nonsedating derivative of barbituric acid that crosses the blood brain barrier. Antitumor activity of merbarone has been described against L1210, B16 melanoma cell line and the M5076 sarcoma cells in phase I studies. Merbarone inhibits DNA synthesis and tumor growth by inducing single strand breaks in DNA. It also inhibits RNA and protein synthesis. We evaluated merbarone in a phase II trial in patients (pts) with recurrent or refractory GBM (7 pts) and high grade anaplastic astrocytoma (7 pts). Fourteen patients (nine males, five females) were treated with merbarone at a dose of 1000 mg per m2 per day by continuous intravenous infusion for 5 days every 3 weeks. Every patient received at least two cycles of treatment. No complete or partial responses were observed, although one patient had stable disease lasting 20 weeks. Our conclusion is that merbarone is ineffective against GBM and high-grade anaplastic astrocytoma at the dose and schedule in which it was administered in this trial.

A phase II trial of merbarone (NSC 336628) in the treatment of recurrent epithelial ovarian carcinoma. A Gynecologic Oncology Group Study.

BACKGROUND: Patients with recurrent epithelial ovarian carcinoma who progress through a cisplatin-based regimen or recur less than 6 months after discontinuing cisplatin, have limited therapeutic options. The Gynecologic Oncology Group conducted a Phase II trial of merbarone in this patient population. METHODS: Twenty-seven patients with recurrent epithelial ovarian carcinoma who had previously received one prior cisplatin-based regimen were scheduled to receive 1000 mg/m2 of merbarone by continuous intravenous infusion through a central line each day for five days every four weeks. RESULTS: Of the 27 patients entered, one was ineligible because of wrong primary, and two never received the drug, leaving 24 patients evaluable for toxicity. Twenty of 24 were evaluable for response. The regimen was well tolerated with only one episode each of GOG grade 3 leukopenia (4%) or grade 4 granulocytopenia (4%). There was one episode (4%) of GOG grade 3 gastrointestinal toxicity. Prior to increasing the infusate concentration to 4 mg/ml, there was one episode (4%) of altered mental status which, in retrospect, may have been secondary to iatrogenic hyponatremia. There were two partial responses (10%) (95% confidence interval 1.2-31.7%). CONCLUSIONS: Merbarone exhibited minimal activity at this schedule in this pretreated group of patients with epithelial ovarian carcinoma.

A phase II trial of merbarone (NSC 336628) as salvage therapy for squamous cell carcinoma of the cervix. A Gynecologic Oncology Group Study.

Twenty-seven patients with previously irradiated unresectable recurrent squamous carcinoma of the cervix who had failed one prior cytotoxic regimen received 1,000 mg/m2 per day of merbarone given by continuous i.v. infusion for 5 days every 4 weeks through a central line. One patient was never treated, and four were inevaluable for response, leaving 26 patients evaluable for toxicity and 22 evaluable for response. The major adverse effect was myelosuppression with 6/26 (23%) experiencing Gynecologic Oncology Group (GOG) grade 3 or 4 leukopenia. There were two episodes (3.8%) of GOG grade 3 SGOT elevation. There were two patients (9.0%) who developed mental status changes classified as grade 3 neurotoxicity. This neurotoxicity may have been secondary to iatrogenic hyponatremia caused by the large volumes of 5% glucose infusion required at the original infusate concentration. After the concentration of the merbarone infusate was increased to 4 mg/ml, no further problems with hyponatremic neurotoxicity were encountered. The overall response rate was 2/22 (9.0%) (95% confidence interval 1.1-29.2%). In this pretreated population with recurrent squamous cervical carcinoma, merbarone exhibited only minimal activity.

Evaluation of merbarone (NSC 336628) in disseminated malignant melanoma. A Southwest Oncology Group study.

Merbarone, NSC 336628, is an investigational anticancer drug with activity against experimental animal tumors including melanoma. This paper presents results of a Phase II clinical study of merbarone in patients with biopsy proven stage IV malignant melanoma without prior chemotherapy and with no evidence of CNS involvement. Thirty-five patients with median age 58 (range 27-81), with performance status 0-2 were treated with merbarone 1000 mg/m2/day for five days by intravenous continuous infusion repeated every 3 weeks. All patients (21 males and 14 females) were evaluable for toxicity. Two patients were not evaluable for response having been removed from protocol treatment due to toxicity and received other treatment during the first course of chemotherapy. Among the evaluable patients there was one complete response in a supraclavicular lymph node lasting four months and one partial liver response lasting three months. The remaining thirty-one patients were non-responders. Of these one had a stable disease lasting 21 months. The overall objective response rate was 6% (2/35) with a 95% confidence interval of 1%-19%. Twenty-six of the 35 patients have died. The estimated median survival of the entire group was 9 months with a 95% confidence interval six to eleven months. Renal toxicity was dose-limiting and manifested as increasing serum creatinine (54% of patients), proteinuria (51%) and hematuria (9%). One patient experienced grade 4 creatinine increase, proteinuria and acute renal failure. Other toxicities included nausea (71%), vomiting (51%0, malaise (23%), weakness (20%), alopecia (17%), diarrhea (17), anorexia (14%) transaminase (SGOT, SGPT) increase (14%), constipation (14%), alkaline phosphatase or 5'nucleotidase increase (9%), and fever (9%). Hematologic toxicity (granulocytopenia, leukopenia, and anemia) was generally mild and infrequent (29%, only one patient had grade 4 granulocytopenia). Overall 9 patients (26%) had at least one grade 3 toxicity. We conclude that merbarone at this dose and schedule has detectable but minimal activity in the treatment of metastatic malignant melanoma and given the significant renal toxicity this schedule does not merit further evaluation in this disease.

Hepatoma/merbarone. A Southwest Oncology Group study.

Sixteen eligible patients with hepatocellular carcinoma, previously untreated, received merbarone 1000 mg/m2/d for five consecutive days every 21 days. No complete or partial response to treatment was obtained. Seven patients had grade 4 granulocytopenia. One patient died with renal failure. Merbarone in this dose and schedule was ineffective in the treatment of hepatocellular carcinoma.

Phase II evaluation of merbarone in renal cell carcinoma.

The Southwest Oncology Group (SWOG) studied the response rate and toxicity of merbarone (1,000 mg/m2 IV continuous infusion days 1-5, q 21 days) in patients with advanced metastatic renal cell carcinoma. Among 36 eligible patients, there was one partial response for a response rate of 3% (95% C.I. 0.1-15%). There were no mixed responses. There were no treatment related deaths or adverse drug reactions. Significant anemia, diarrhea, and hypercalcemia were observed. Mild to moderate degrees of malaise/fatigue/lethargy, dizziness/vertigo, hyperglycemia, creatinine increase, nausea, vomiting, weight loss, pedal edema, dyspnea, and granulocytopenia were noted. Merbarone does not have significant activity as a single agent in advanced renal cell carcinoma.

Phase II study of merbarone (NSC 336628) in patients with advanced gastric carcinoma.

Merbarone, 5-(N-phenylcarboxamido)-2-thiobarbituric acid (NSC 336628), is a derivative of barbituric acid and represents a unique class of antineoplastic agents. We treated 16 patients with advanced gastric carcinoma in a phase II study of merbarone. All patients were previously untreated with chemotherapy or biological therapy. The starting dose of merbarone was 1000mg/m2 infused over 24 hr for 5 consecutive days every 21 days. A median of two courses (range, 1-7) was given. None of the patients achieved a complete or partial response; however, 3 patients achieved a transient minor response. Toxicity was mild to moderate in most patients, but 1 patient died of treatment-related neutropenia and sepsis. Our data suggest that merbarone at this dose and schedule is inactive against gastric carcinoma. The evidence of minor response suggests that analog research may be worthwhile to pursue.

Phase II trial of merbarone in pancreatic carcinoma. A Southwest Oncology Group study.

Twenty-nine patients with advanced pancreatic adenocarcinoma were treated with merbarone, utilizing a daily intravenous schedule for 5 days. Only two partial responses of short duration were observed. The major toxicities were renal, with an increase in creatinine or proteinuria in 17 patients, and mild to moderate nausea and vomiting seen in 22 patients. Merbarone in this dose and schedule has minimal activity in pancreatic cancer.

Phase II study of taxol, merbarone, and piroxantrone in stage IV non-small-cell lung cancer: The Eastern Cooperative Oncology Group Results.

BACKGROUND: Patients with metastatic (stage IV) non-small-cell lung cancer usually have a poor prognosis and disease refractory to chemotherapy. Three new agents--taxol, merbarone, and piroxantrone--have shown promising antitumor treatment in vitro and in animals. Taxol is an antimicrotubular agent that interferes with mitosis during cell division. Merbarone, a conjugate of thiobarbituric acid and aniline, is a topoisomerase II inhibitor, which thus inhibits DNA synthesis and tumor growth. Piroxantrone, an anthracenedione derivative, is a DNA intercalating agent that has shown potent antitumor activity in animal studies. PURPOSE: Our randomized phase II study was designed to evaluate the efficacy and toxicity of these agents in the treatment of stage IV metastatic non-small-cell lung cancer. METHODS: Eligible patients (119) were randomly assigned to receive one of the three treatments given every 3 weeks: 250 mg/m2 taxol by a 24-hour intravenous infusion, 1000 mg/m2 merbarone by continuous intravenous infusion through a central catheter daily for 5 days, or 150 mg/m2 piroxantrone by intravenous infusion over 1 hour. Patients had received no chemotherapy. Response and toxicity were evaluated every 3 weeks. RESULTS: Twenty-five patients were randomly assigned to receive taxol, 47 to receive merbarone, and 47 to receive piroxantrone. One of 44 assessable patients (2.3%) treated with piroxantrone had a complete response. Rates for partial response were 20.8% (five of 24 patients) and 5.7% (two of 35) for assessable patients treated with taxol or merbarone, respectively. One-year survival rates were 41.7%, 21.6%, and 22.6%, and median survival times were 24.1, 19.9, and 29.3 weeks for taxol, merbarone, and piroxantrone, respectively. These differences were not statistically significant, but this study was not designed to compare survival. In general, toxicity was manageable. With premedication, no anaphylaxis was observed with taxol. The most common toxic effects were leukopenia with taxol or piroxantrone treatment and thromboembolic complications with merbarone. Death directly related to treatment occurred in 4% (one patient), 11.4% (four), and 5% (two) of the assessable patients receiving taxol, merbarone, and piroxantrone, respectively. Cardiotoxicity and neurotoxicity occurred only occasionally in all three arms. CONCLUSION: On the basis of the response rate (20.8% partial response) and 1-year survival rate (41.7%), taxol is an active agent for the treatment of metastatic non-small-cell lung cancer. Merbarone and piroxantrone are relatively inactive. IMPLICATIONS: Further study of taxol is warranted. In future studies, taxol should be combined with other agents, and granulocyte colony-stimulating factor should be used to ameliorate myelosuppression.

A phase II study of merbarone in patients with adenocarcinoma of the pancreas.

Merbarone, a nonsedating derivative of thiobarbituric acid that has demonstrated antineoplastic activity against a variety of murine tumors, was evaluated in a phase II trial in patients with advanced, measurable adenocarcinoma of the pancreas. Seventeen patients were treated at a starting dose of 1000 mg/m2/day for 5 days by continuous intravenous infusion; the dose was escalated in accordance with the toxicity experienced, and no dosage reductions owing to toxicity were required. No complete or partial responses were observed, and only one minor response was documented, suggesting that merbarone is ineffective against pancreatic cancer at the doses and schedule in which it was administered in this trial.

Phase II trial of merbarone in soft tissue sarcoma. A Southwest Oncology Group study.

Thirty-seven patients with advanced soft tissue sarcoma were treated with merbarone utilizing a daily intravenous schedule for five days. Only one partial response was observed in the thirty-three evaluable patients. The major toxicities were renal, with elevation of creatinine and/or proteinuria, and gastrointestinal, with mild to moderate nausea and vomiting. Merbarone in this dose and schedule has minimal activity in soft tissue sarcoma.

[The mechanism of action of the bioflavonoid lespeflan and the antihypoxant TB-4 on nitrogen metabolism in animals with acute kidney failure]. / K mekhanizmu deistviia bioflavonoida lespeflana i antigipoksanta TB-4 na azotistyi obmen u zhivotnykh s ostroi pochechnoi nedostatochnost'iu.

The changes in the levels of urea and creatinine caused by the new native preparation lespeflanum and the antihypoxant TB-4 were studied in animal experiments. The agents tested produced a significant hypoazotemic effect in acute renal failure. Lespeflanum showed diuretic and natriuretic effects in healthy animals, elevated plasma aldosterone levels and decreased hepatic arginase activity. There was a normalization of thioldisulfide metabolism in patients treated with lespeflanum and TB-4. The hypoazotemic effect of lespeflanum was due both to its anabolic and anticatabolic effects. Lespeflanum is recommended for wide clinical application to treat patients with chronic renal failure.

Phase I clinical and pharmacological study of merbarone.

Merbarone, a nonsedating derivative of thiobarbituric acid, has demonstrated excellent activity against certain murine tumors, including L1210 and P388 leukemias, B16 melanoma, and M5076 sarcoma. Preclinical studies suggested that the antitumor effects of this drug were schedule dependent, since repeated dosing increased killing of tumor cells when compared to intermittent injections. We have completed a Phase I clinical and pharmacological study of merbarone in which the drug was administered both as a 2-h infusion and as a continuous i.v. infusion over 24 h. In view of the increased toxicity observed in animals following bolus injections and the possibility of schedule-dependent anticancer activity, a schedule of drug administration daily for 5 days was selected. Fifty patients with advanced cancer were treated at dose levels that ranged from 100 to 1500 mg/m2/day. When the drug was administered by peripheral vein, phlebitis was observed at the infusion site at daily doses greater than or equal to 150 mg/m2. Therefore, all patients who received drug doses greater than or equal to 200 mg/m2 were treated by continuous i.v. infusion using central venous catheters. Renal insufficiency, initially observed at a dose of 1000 mg/m2/day, was the dose-limiting toxic reaction at 1500 mg/m2/day. Three of five patients treated at the highest dose level were unable to complete the infusion due to this effect. Marked hypouricemia was observed in all patients. Other toxic effects were mild and included nausea, fatigue, leukopenia, thrombocytopenia, and anorexia. Alopecia was noted in several patients who received doses greater than or equal to 1000 mg/m2/day. No major antitumor effects were observed. Dose-dependent, steady-state plasma concentrations of merbarone were reached within 24-48 h after beginning the continuous i.v. infusion. Elimination of drug from plasma followed a two-compartment model, with a t1/2 alpha of 4.2 h and a t1/2 beta of 15.3 h. Renal excretion of merbarone and its major metabolites accounted for less than 30% of the administered dose. We conclude that merbarone is relatively well tolerated with few constitutional symptoms. The current formulation of the drug causes phlebitis when administered by peripheral vein, and renal insufficiency is commonly observed at daily doses which exceed 1250 mg/m2. The recommended dose for extended Phase II evaluation is 1000 mg/m2/day daily for 5 days administered by central venous catheter.