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PubMed2001

RTOG 96-10: reirradiation with concurrent hydroxyurea and 5-fluorouracil in patients with squamous cell cancer of the head and neck.

PURPOSE: Patients with recurrent squamous cell cancer of the head and neck (SCH&N) are generally treated with systemic chemotherapy. Improvement in survival has not occurred, despite an increased objective response rate. This study was undertaken to explore the feasibility and toxicity, and estimate the therapeutic impact of, reirradiation (RRT) with concurrent hydroxyurea and 5-fluorouracil. METHODS AND MATERIALS: The eligibility requirements included SCH&N presenting as a second primary or recurrence > or =6 months after definitive RT to > or =45 Gy, with > or =75% of the tumor volume within the previous field. The cumulative spinal cord dose was limited to 50 Gy, and measurable disease was required. Four weekly cycles were given, each separated by 1 week of rest. A cycle consisted of 5 days, Monday through Friday, of 1.5-Gy twice-daily repeated RT, with the fractions separated by > or =6 h, with 1.5 g of hydroxyurea given 2 h and 300 mg/m2 of a 5-fluorouracil IV bolus given 30 min before each second daily fraction. RESULTS: Eighty-six patients were entered; 81 patients were assessable. The median prior radiation dose was 61.2 Gy. The 4 planned cycles were delivered in 79% of patients. Grade 3 mucositis occurred in 14% of patients, and Grade 4 in 5%. Grade 3 acute pharyngeal toxicity was seen in 17%. Grade 3 neutropenia occurred in 9%, Grade 4 in 10%, and Grade 5 in 7%. Six patients died of treatment-related toxicity. Two died of hemorrhage from the tumor site without thrombocytopenia. With a median follow-up of 16.3 months for living patients, the estimated median overall survival was 8.2 months and the estimated 1-year survival rate 41.7%. Patients treated >3 years after the previous RT had a 1-year survival rate of 48% compared with 35% for patients treated within 3 years (p = 0.017). The 1-year survival rate for patients with a second primary was 54% compared with 38% for patients with recurrence (p = 0.083). CONCLUSION: Repeated RT with concurrent chemotherapy as given in this study is a feasible approach for selected, previously irradiated patients with SCH&N and may produce increased median and 1-year survival rates compared with systemic chemotherapy trials reported in the literature. A randomized study should be conducted to compare these two different approaches.

Adult↗

PubMed1998

Colorimetric determination of hydroxyurea in human serum using high-performance liquid chromatography.

A high-performance liquid chromatography assay for hydroxyurea in human serum was developed based on a commercial colorimetric assay kit for urea (Sigma Diagnostics). Serum (0.5 ml), spiked with methylurea as an internal standard, was treated with 70% perchloric acid. Supernatant (0.2 ml) was combined with 0.7 ml of BUN acid reagent and 0.6 ml of BUN color reagent. The resulting colored reactant (100 microl) was analyzed on a 300 x 3.9 mm Bondclone 10 C18 column coupled with a UV-Vis detector, at 449 nm. The mobile phase was 13% acetonitrile in water. Retention times of colored derivatives of hydroxyurea and methylurea were 6.5 and 12.2 min, respectively. The log-log calibration curve was linear from 0.0065 to 1.31 mM. Average accuracy was 99.9+/-4.0% and the intra- and inter-day error of assay did not exceed 11%.

Chromatography, High Pressure Liquid↗

PubMed1998

New isocratic high-performance liquid chromatographic procedure to assay the anti-sickling compound hydroxyurea in plasma with ultraviolet detection.

A new procedure using high-performance liquid chromatography (HPLC) with ultraviolet detection to assay hydroxyurea (HU) levels in plasma has been developed. The drug was isolated from plasma by a direct deproteinization process with sulfosalicylic acid. Following neutralization of the acidic supernatant, an aliquot was loaded onto an Aminex HPX-72S column (300x7.8 mm). Chromatography was performed at 55 degrees C using a mobile phase consisting of acetonitrile-0.025 M ammonium sulfate buffer (pH 8.5) including 0.1% triethylamine, 0.01 M sodium sulfate, and 5 mM sodium heptane sulfonate. The UV absorbance of effluent was monitored at 214 nm. A flow-rate of 0.8 ml/min was used for analyzing HU in both human and mouse plasma. Under these conditions, the drug eluted at 12.6 min. The assay possessed linearity up to 425 microg/ml, with a lower limit of quantitation of 3.32+/-0.0004 microg/ml (mean+/-S.D., n=10). Intra-day and inter-day coefficients of variation were less than 8.5% and 8.7% respectively. Absolute differences were less than 7.4%. The method has been employed in clinical studies and the sensitivity of the assay was shown to be adequate for characterizing the plasma pharmacokinetics of HU in mice. In conclusion, the procedure described herein could be ideally suited for therapeutic monitoring of hydroxyurea.

Animals↗

PubMed2000

Predicting the effectiveness of hydroxyurea in individual sickle cell anemia patients.

The study described in this paper was undertaken to develop the ability to predict the response of sickle-cell patients to hydroxyurea (HU) therapy. We analyzed the effect of HU on the values of 23 parameters of 83 patients. A Student's t-test was used to confirm (Rodgers GP, Dover GJ, Noguchi CT, Schechter AN, Nienhuis AW. Hematologic responses of patients with sickle cell disease to treatment with hydroxyurea, N Engl J Med 1990;322;1037-44) at the 0. 001 level that treatment with HU increases the proportion of fetal hemoglobin (HbF), and the average corpuscular volume (MCV) of the red blood cells. Correlation analysis failed to establish a statistically significant relationship between any of the 23 parameters and the HbF response. Linear regression analysis also failed to predict a patient's response to HU. On the other hand, artificial neural network (ANN) pattern-recognition analysis of the 23 parameters predicts, with 86.6% accuracy, those patients that respond positively to HU and those that do not. Furthermore, we have found that the values of only 10 of the 23 parameters (listed in the body of this paper) are sufficient to train ANNs to predict which patients will respond to HU.

Adolescent↗

PubMed2003

Zinc(II)-mediated inhibition of a ribonuclease by an N-hydroxyurea nucleotide.

The inhibition of ribonuclease Bi by 3'-N-hydroxyurea-3'-deoxythymidine 5'-phosphate is enhanced by 30-fold in the presence of Zn(2+). Thus, an N-hydroxyurea nucleotide can recruit Zn(2+) to inhibit the enzymatic activity of a ribonuclease. This result engenders a general strategy for the inhibition of non-metalloenzymes by metal complexes.

Endoribonucleases↗

PubMed1992

Benzothiazole hydroxy ureas as inhibitors of 5-lipoxygenase: use of the hydroxyurea moiety as a replacement for hydroxamic acid.

A novel series of N-[(2-benzothiazolylthio)alkyl]-N'-hydroxyurea derivatives (9-25) was synthesized and evaluated for biological activity as inhibitors of 5-lipoxygenase both in vivo (mouse zymosan peritonitis assay) and in vitro (Ca2+ ionophore-stimulated human peripheral blood leukocyte model). The compounds of this series were based on the corresponding hydroxamic acid derivatives (1, 3, 4, and 5) which were moderately active in vitro but inactive in vivo. A number of compounds in the hydroxyurea series exhibited oral activity for 5-lipoxygenase inhibition. Results of studies relating structure to in vivo and in vitro 5-lipoxygenase activity are reported.

Animals↗

PubMed1997

Structure-activity relationships of N-hydroxyurea 5-lipoxygenase inhibitors.

The discovery of second generation N-hydroxyurea 5-lipoxygenase inhibitors was accomplished through the development of a broad structure-activity relationship (SAR) study. This study identified requirements for improving potency and also extending duration by limiting metabolism. Potency could be maintained by the incorporation of heterocyclic templates substituted with selected lipophilic substituents. Duration of inhibition after oral administration was optimized by identification of structural features in the proximity of the N-hydroxyurea which correlated to low in vitro glucuronidation rates. Furthermore, the rate of in vitro glucuronidation was shown to be stereoselective for certain analogs. (R)-N-[3-[5-(4-Fluorophenoxy)-2-furyl]-1-methyl-2-propynyl]-N-hydroxyure a (17c) was identified and selected for clinical development.

Animals↗

PubMed1998

A phase I clinical trial of prolonged infusion of hydroxyurea in combination with hyperfractionated, accelerated, external radiation therapy in patients with advanced squamous cell cancer of the head and neck.

BACKGROUND: Preclinical data suggested that sustained inhibition of the anabolic enzyme, ribonucleotide reductase (RR), by hydroxyurea (HU) may be critical for the anticancer effects of the drug. A phase I trial of continuous infusion HU with concomitant hyperfractionated, accelerated radiation therapy (CHU-CHRT) was initiated to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT) of HU in patients with locally advanced squamous cell carcinoma (SCC) of the head and neck. METHODS: Patients were required to have histologically-documented and radiographically-staged locally advanced SCC of the hypopharynx (AJC stages II, III or IV), oropharynx (AJC stage IV), or oral cavity (AJC stage IV) not amenable to reasonable surgical resection. Eligible patients had adequate bone marrow, hepatic, and renal function and had to give informed consent. Concomitant, hyperfractionated, accelerated radiation therapy (CHRT) consisted of 1.2 Gy BID (6 hour minimum interfraction interval) on weekdays and 1.2 Gy delivered daily on the weekends to a total tumor dose of 74.4 Gy. Continuous infusion hydroxyurea (CHU) was administered at 0.25-0.375 mg/m2/min as a continuous intravenous infusion daily for 5 days with weekends days off for the duration of the radiation therapy. The dose of HU was increased by 0.125 mg/m2/min between dose levels until DLT was reached in 2/6 patients. If the primary had a complete clinical response and biopsies were negative, planned neck dissections were performed. RESULTS: Fifteen patients were enrolled and are evaluable. The initial dose level, 0.25 mg/m2/min was tolerated by 3/3 patients. At 0.375 mg/m2/min, 3/6 patients experienced grade 3-4 infections, with one patient having a non-fatal, subendocardial infarction. At 0.313 mg/m2/min, no patient experienced DLT. CONCLUSION: The MTD for CHU-CHRT was 0.313 mg/m2/min. The toxicities were primarily mucosal and a phase II study is in progress.

Adult↗

PubMed2000

A phase I-II study of concomitant chemoradiotherapy with paclitaxel (one-hour infusion), 5-fluorouracil and hydroxyurea with granulocyte colony stimulating factor support for patients with poor prognosis head and neck cancer.

BACKGROUND: Concomitant chemoradiotherapy is an effective treatment modality for advanced head and neck cancer, but improved regimens are needed. We sought to define the toxicities, recommended phase II dose, and outcome of a combination chemotherapy regimen with concomitant hyperfractionated radiotherapy in patients with poor prognosis cancers of the head and neck, including those having received prior curative intent radiotherapy. PATIENTS AND METHODS: From 1995 until 1997, 54 patients were treated, 25 of whom had received a prior full course of radiotherapy to the head and neck. Patients were treated with 5-fluorouracil (5-FU) 600 mg/m2/day continuous infusion x 5 days (days 1-5), hydroxyurea, 500 mg p.o. bid x 11 doses (days 1-6) and paclitaxel (60-150 mg/m2) by one-hour infusion on day 2 using a dose escalation strategy. Radiotherapy was given concomitantly on days 2-6, 150 cGy bid. Each of 4-5 cycles was delivered every other week. RESULTS: The MTD of paclitaxel was 100 mg/m2. The regimen was feasible; radiotherapy was delivered at a median of 7300 cGy and 83% of patients received > or = 80% planned dose intensity. Hematological toxicity, with granulocyte colony stimulating factor, was very mild. Dose limiting toxicities were mucositis and dermatitis. Despite poor prognosis, two-year survival was 45%. CONCLUSIONS: The recommended phase II dose of this regimen is 5-FU 600 mg/m2/day x 120 hours (days 1-5), hydroxyurea 500 mg p.o. b.i.d. x 11 doses (days 1-6), paclitaxel 100 mg/m2 over one hour on day 2, and radiotherapy 150 cGy b.i.d. days 2-6. Concomitant chemotherapy and re-irradiation was feasible on this protocol and resulted in long-term survival in patients without other curative intent options.

Adult↗

PubMed2003

Emergence of Philadelphia positive chronic myeloid leukaemia during treatment with hydroxyurea for Philadelphia negative essential thrombocythaemia.

A 58-yr-old male patient with essential thrombocythaemia (ET) developed chronic myeloid leukaemia (CML) after continuous uneventful treatment with hydroxyurea for 18 yr. G-banding analyses of bone marrow cells had repeatedly demonstrated normal male karyotype before this event, but t(9;22)(q34;q11) was demonstrated after the event. An unrelated allogeneic stem cell transplantation was performed. Blood and bone marrow morphology, and the karyotype were normalised and the patient is in good health 1 yr post-transplant. There are no previous reports in the literature about the emergence of CML during treatment with hydroxyurea.

Antineoplastic Agents↗

PubMed2003

Hydroxyurea-induced pneumonitis in a patient with chronic idiopathic myelofibrosis after prolonged drug exposure.

We describe a 63-yr-old patient diagnosed with chronic idiopathic myelofibrosis whose disease was treated with hydroxyurea for 2 yr. He developed respiratory symptoms that were extensively investigated including lung biopsy. Clinical, radiological and histological features were compatible with a diagnosis of hydroxyurea-induced pneumonitis. Following drug withdrawal there was remarkable improvement in clinical and radiological findings.

Diagnosis, Differential↗

PubMed1979

Phase-specific cytotoxicity in vivo of hydroxyurea on murine fibrosarcoma cells synchronized by centrifugal elutriation.

The S-phase-specific cytotoxicity of hydroxyurea (HU) was tested on synchronized murine fibrosarcoma (FSa) cells lodged in the lungs of C3Hf/Bu mice. FSa cells from primary asynchronous cultures were separated and synchronized on the basis of size by centrifugal elutriation. Flow microfluorometry (FMF) was used to determine the cell-cycle parameters and the relative synchrony of the separated populations. After elutriation, 8000 viable FSa cells from each fraction, along with 10(6) heavily irradiated tumour cells (unseparated) were injected i.v. into whole-body-irradiated mice (20 per group). Under these conditions, 95% of the injected cells, regardless of size or position in the cell cycle, are arrested in the lungs. Twenty minutes later, hydroxyurea (HU, 1 mg/g) was administered i.p. into 10 animals of each group. Fourteen days later the animals were killed, their lungs removed and fixed, and the number of macroscopic tumour nodules counted. Killing of the initially injected cells by HU, as evidenced by a reduction in lung colonies in treated animals, correlated with the precentage of S-phase cells in each fraction. The greatest effect, an 80% reduction in colony number, was seen in Fraction 8, containing the largest percentage of S-phase cells (65%). These results demonstrate the usefulness of this procedure as a rapid method for characterizing the phase specificity of chemotherapeutic drugs in vivo.

Animals↗

PubMed2001

Function of GATA transcription factors in hydroxyurea-induced HEL cells.

HEL cells, a human erythroleukemia cell line, mainly express the fetal (gamma) globin gene and trace amount of the embryonic (epsilon) globin gene, but not adult (beta) globin gene. Here we show that hydroxyurea (HU) can induce HEL cells to express adult (beta) globin gene and lead these cells to terminal differentiation. Results showed in Gel mobility shift assays that GATA factors could specifically bind to the regulatory elements of human beta-globin gene, including the proximal regulatory element (the beta-promoter) and the distal regulatory elements (the DNase I hypersensitive sites in the LCR, HS2-HS4 core sequences). However, the DNA binding patterns of GATA factors were quite different between HU-induced and uninduced HEL cells. Western-blot analysis of nuclear extracts from both the uninduced and HU-induced HEL cells revealed that the level of GATA-2 transcription factor decreased, whereas the level of GATA-1 transcription factor increased following the time of hydroxyurea induction. Furthermore, using RT-PCR analysis the expression of human beta-globin gene in HU-induced HEL cells could be blocked again when HEL cells were incubated in the presence of antisense oligonucleotides for hGATA-1, suggesting that the upregulation of hGATA-1 transcription factor might be critical for the expression of human beta-globin gene in HU-induced HEL cells.

Cell Differentiation↗

PubMed2002

Bloom's syndrome protein response to ultraviolet-C radiation and hydroxyurea-mediated DNA synthesis inhibition.

Bloom's syndrome (BS) arises through mutations in both copies of the BLM gene that encodes a RecQ 3'-5' DNA helicase. BS patients are predisposed to developing all the cancers that affect the general population, and BS cells exhibit marked genetic instability. We showed recently that BLM protein contributes to the cellular response to ionizing radiation by acting as downstream ATM kinase effector. We now show that following UVC treatment, BLM-deficient cells exhibit a reduction in the number of replicative cells, a partial escape from the G2/M cell cycle checkpoint, and have an altered p21 response. Surprisingly, we found that hydroxyurea-treated BLM-deficient cells exhibit an intact S phase arrest, proper recovery from the S phase arrest, and intact p53 and p21 responses. We also show that the level of BLM falls sharply in response to UVC radiation. This UVC-induced reduction in BLM does not require a functional ATM gene and does not result from a subcellular compartment change. Finally, we demonstrate that exposure to UVC and hydroxyurea treatment both induce BLM phosphorylation via an ATM-independent pathway. These results are discussed in the light of their potential physiological significance with regard to the role of BLM in the cellular pathways activated by UVC radiation or HU-mediated inhibition of DNA synthesis.

Adenosine Triphosphatases↗

PubMed1996

Mobilization of Philadelphia-negative peripheral blood mononuclear cells in chronic myeloid leukaemia using hydroxyurea and G-CSF (filgrastim).

A relatively simple and non-toxic out-patient-based regimen for the mobilization of Philadelphia-negative (Ph-ve) mononuclear cells in chronic myeloid leukaemia (CML) was evaluated in 10 patients, nine in stable chronic phase and one in accelerated phase. They received oral hydroxyurea at a mean dose of 3.5 g/m2 daily for 7 d, followed by 300 micrograms of G-CSF daily until the last day of harvesting. In the nine chronic-phase patients the mean number of days from the end of hydroxyurea to the commencement of harvesting was 14.5 (range 10-18). The patient in accelerated phase recovered and was harvested after 6 d. The mean number of aphereses performed was 3.4. Adequate numbers of stem cells were obtained in 9/10 patients judged by our usual criteria. Side-effects were mild in comparison to published intravenous schedules. No patients lost their hair. Five (50%) patients required admission with neutropenic fever which responded to antibiotics in all cases. Four (40%) patients developed a transient rash and four (40%) experienced mild oral mucostis. This level of toxicity enabled half of the patients to be treated entirely on an out-patient basis. The harvest products were analysed for cells belonging to the leukaemic clone by conventional cytogenetics, FISH and PCR. All were PCR positive. The mean Ph positivities by cytogenetics and FISH were comparable at 18.1% and 15% respectively. Half the patients had > 98% normal metaphases. We conclude that this approach is comparable in efficacy to published intravenous regimens and significantly less toxic. It can be safely used at diagnosis before interferon therapy commences.

Administration, Oral↗

PubMed1997

Cellular effects of hydroxyurea in Hb SC disease.

Hb S polymerizes in high-density Hb SC disease erythrocytes. We hypothesized that hydroxyurea -- perhaps independent of increasing Hb F -- might reduce the density of these cells. Six Hb SC disease patients were given 1000mg of hydroxyurea daily and blood counts, cell volumes, and cell density were followed for 12 months. There was an increase in MCV and reticulocyte MCV. A fall in absolute reticulocyte counts, high-staining ('stress') reticulocytes, serum bilirubin, and an increase in the ratio of mature red cell haemoglobin to reticulocyte haemoglobin, coupled with a rise in the haematocrit inferred a decrease in haemolysis and 'stress erythropoiesis'. An improvement in cell hydration was suggested by a reduction in reticulocyte mean cell haemoglobin concentration (CHCMr), red cells and reticulocytes with CHCM > 38, and decreased dense cell counts estimated by phthalate ester and Percoll-Larex gradients. After 4-5 months treatment, Hb F rose in a few patients but the overall difference in pre- and post-treatment Hb F was not significant. A decline in cell density should diminish the polymerization tendency of Hb S in Hb SC disease.

Anemia, Sickle Cell↗

PubMed2002

Chronic myeloid leukaemia with marked thrombocytosis in a patient with thalassaemia major: complete haematological remission under the combination of hydroxyurea and anagrelide.

The co-existence of thalassaemia major and chronic myeloid leukaemia (CML) is a very rare event. We report a 32-year-old man with thalassaemia major whose progressively increasing leukocytosis and thrombocytosis led to the diagnosis of CML confirmed by the characteristic t(9;22)(q34;q11) chromosomal translocation and the bcr-abl (b3a2) DNA fusion. The patient was treated with hydroxyurea and anagrelide. This combination resulted in the satisfactory control of both the white blood cell and platelet counts, which has continued over the past 14 months with no major side-effects, albeit with no molecular response. The administration of hydroxyurea was also associated with a significant HbF increase.

Adult↗

PubMed2002

Traditional therapies: glucocorticoids, azathioprine, methotrexate, hydroxyurea.

The 'old favourites' used for treatment of inflammatory diseases, and hence, the original immunomodulators, include the glucocorticoids, azathioprine, methotrexate and hydroxyurea. Glucocorticoids are still one of the most effective anti-inflammatory agents because they work on several different intracellular processes and hence, block many components that contribute to inflammatory and immune responses. They bind to intracellular glucocorticoid receptors which transport them into the nucleus. Here the receptor/steroid complex may bind to many genes that interact with transcription factors including NFkappaB and AP-1, to inhibit their activation, thereby preventing activation of many genes encoding immune effector and pro-inflammatory cytokines. Also, protein kinases involved in intracellular signalling, are directly activated resulting in phosphorylation of various targets of which Annexin (AXA)-1 is critical in inhibiting biosynthesis of both purines and DNA. This results in reduced proliferation of B and T lymphocytes, reduced immune effector mechanisms and reduced recruitment of mononuclear cells including monocytes into sites of immune inflammation. Methotrexate also blocks DNA synthesis and hence cellular proliferation but also induces release of adenosine. This inhibits chemotaxis of polymorph neutrophils and release of critical cytokines such as TNF-alpha and Interleukins 6 and 8. Hydroxyurea also inhibits DNA synthesis with inhibitory effects on proliferation of lymphocytes and possibly kerationcytes. Even though many new agents with much greater selectivity are coming through into clinical use, this group of old agents still have an absolutely central position in the therapeutic armamentarium. Their value lies in the fact that they are not 'clean' drugs with narrow effects but they inhibit a wide range of mechanisms involved in immune and inflammatory processes.

Azathioprine↗