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PubMed2004

Increased levels of soluble ICAM-1 in the plasma of sickle cell patients are reversed by hydroxyurea.

Increased adhesive events between the blood vessel endothelium and red and white cells play a central role in the initiation of vasoocclusive crisis in sickle cell disease (SCD). Soluble VCAM-1 levels are increased in the plasma of sickle cell patients and may be reduced during hydroxyurea (HU) therapy. Reports regarding any changes in soluble ICAM-1 (sICAM-1) levels in sickle cell patients, however, are conflicting, and as yet no beneficial effect of HU upon levels has been observed. Thus, we sought to thoroughly investigate changes in sICAM-1 levels in SCD patients and the effect of HU therapy (20-30 mg/kg/day). Plasma sVCAM-1 levels were significantly higher in steady-state SCD patients than in normal controls (766 +/- 86 ng/mL vs. 325 +/- 38 ng/mL, respectively, P < 0.0001). sVCAM-1 levels were decreased in patients on HU therapy (543 +/- 69 ng/mL) compared to those not taking HU; however, this difference was not significant. Plasma sICAM-1 levels were significantly increased in steady-state SCD patients compared to normal individuals (285 +/- 20 ng/mL vs. 202 +/- 16 ng/mL, respectively, P = 0.002), and HU therapy significantly reduced sICAM-1 levels in patients (217 +/- 12, P = 0.027) to levels approaching those of healthy individuals. sVCAM-1 levels inversely correlated with fetal hemoglobin levels in SCD patients, while a nonsignificant inverse trend was observed between sICAM-1 levels and fetal hemoglobin. In conclusion, plasma sICAM-1 levels were significantly increased in SCD patients, and this increase was reversed by hydroxyurea therapy, possibly reflecting reduced endothelial activation in patients taking HU. Such an event may benefit patients by reducing adhesive interactions between white cells and the endothelium.

Adult↗
PubMed2006

Antitumor effects of celecoxib on K562 leukemia cells are mediated by cell-cycle arrest, caspase-3 activation, and downregulation of Cox-2 expression and are synergistic with hydroxyurea or imatinib.

Celecoxib, a specific cyclooxygenase-2 (Cox-2) inhibitor, has been shown to possess antitumor activity in a variety of cancer cells. However, the antitumor activity of celecoxib in hematopoietic tumors, especially in chronic myeloid leukemia (CML), has not been well established. This study was designed to investigate the effect of celecoxib on growth and apoptosis in a human CML cell line (K562 cells) or in primary CML cells, and to examine the synergistic actions of celecoxib and hydroxyurea or imatinib on K562 cell proliferation and apoptosis. Celecoxib significantly inhibited the growth of both K562 and primary CML cells and induced apoptosis in a dose-dependent fashion. The IC50 of celecoxib was 46 microM for inhibition of K562 cell proliferation. The effect of celecoxib on growth inhibition was accompanied by the downregulation of cyclin D1 and cyclin E and p-Rb expression, the upregulation of P16(INK4a) and P27KIP expression, and a G1-S phase arrest of the cell cycle. The pro-apoptotic effect of celecoxib was determined to be mediated by caspase-3 activation. When K562 cells were pretreated with DEVD-fmk, a specific inhibitor of caspases, the apoptotic activity of celecoxib was, in part, abrogated. Importantly, we demonstrated for the first time that K562 cells were Cox-2-positive both at the mRNA and protein levels. We noted the following observations: (i) we detected Cox-2 mRNA in K562 cells by reverse transcription-PCR (RT-PCR) and protein expression by western blot analysis; (ii) Cox-2 expression in K562 cells was stimulated by IL-1beta, a specific inducing agent of Cox-2 expression; (iii) primary CML cells from CML patient bone marrow also exhibited Cox-2 protein expression. Furthermore, Cox-2 expression was downregulated at higher doses of celecoxib (80-160 microM), suggesting a Cox-2-dependent mechanism was involved in the drug's effects of growth inhibition and induction of apoptosis. In addition, a synergistic effect was observed when cells were exposed to low-dose celecoxib (40 microM) and hydroxyurea (10 mM) or a combination of celecoxib (40 microM) and imatinib (0.2 microM). These findings provide the basis for uncovering the mechanism of celecoxib's antitumor effects and developing a new therapeutic strategy for treating CML.

Antineoplastic Agents↗
PubMed2006

Hospitalization rates and costs of care of patients with sickle-cell anemia in the state of Maryland in the era of hydroxyurea.

The multicenter study of hydroxyurea (MSH) in sickle-cell anemia (SCA) demonstrated that patients treated with hydroxyurea (HU) had a 44% decrease in hospitalizations when compared with those taking placebo. A subsequent study looking at the cost-effectiveness of HU showed that decreased hospitalizations for painful crisis accounted for the majority of cost savings in those taking HU. The purpose of this study was to examine whether the expected decrease in hospital utilization occurred after the approval of HU in Maryland. We used data collected by the Maryland Health Services Cost Review Commission to obtain SCA discharge data for Maryland from FY1995 through FY2003. We also reviewed the inpatient and outpatient charts of all adults with SCA admitted to a large university hospital during 2003. Hospitalization rates for adults with SCA in Maryland have increased significantly since approval of HU. While the total costs of inpatient care in Maryland are estimated to have increased by 31% above inflation from 1995 to 2003, the costs of inpatient care for adult SCA patients has increased by almost 60% above inflation. By comparison, there has been no significant increase in the pediatric hospitalization rate. We found that 70% of patients in one hospital who were appropriate candidates for HU were not taking the medication. Hospital utilization among adults with SCA has increased significantly. There are likely many factors that have played a role in this increase. One factor that appears to be involved is the underutilization of HU.

Adolescent↗
PubMed1984

Treatment of polycythemia vera with hydroxyurea.

Conventional treatment of polycythemia vera (PV) with radioactive phosphorus or alkylating agents is associated with a significant excess of acute leukemia and cancer of the gastrointestinal tract and skin. There is thus a need for a nonmutagenic agent in the treatment of this disorder. Hydroxyurea (HU) was administered to 118 patients with a loading dose of 30 mg/kg/day for 1 week, which was then reduced to 15 mg/kg/day. Initial control of the elevated hematocrit and platelet count was achieved within 12 weeks in over 80% of patients. Long-term disease control was defined and the accumulative 1-year failure-free survival was 73% in the previously untreated patients and 59% in those patients previously treated with other myelosuppressive modalities. The HU was well tolerated and cytopenia, which generally occurred within the first 8 weeks of therapy, was transient and of little clinical significance. However, it is recommended because of this toxicity that HU be administered initially at a dose of 15-20 mg/kg/day. Three patients developed acute leukemia; two were untreated and one had had myelosuppressive therapy. Hydroxyurea is an effective agent in the treatment of PV, but continued assessment of its mutagenic potential is necessary.

Acute Disease↗
PubMed1992

Treatment of acute myeloid leukemia in the elderly with low-dose cytarabine, hydroxyurea, and calcitriol.

Twenty-nine patients aged 62-82 years with acute myeloid leukemia (AML) were treated with a 21-day course of continuous infusion cytarabine, oral hydroxyurea, and 1,25-dihydroxyvitamin D3 (calcitriol). Ten patients had an antecedent myelodysplastic syndrome. Calcitriol was continued as the only postremission therapy. Thirteen patients (45%) obtained a complete remission, and 10 patients (34%) had a partial response for an overall 79% response rate. There were three early deaths. The median remission duration was 9.8 months. Overall median survival was 12 months for all patients and 14 months for responding patients. All responding patients had marked bone marrow hypoplasia. Twenty patients received part or all of their chemotherapy as outpatients. This regimen has acceptable toxicity and can result in prolonged remissions in elderly, high-risk patients with AML. The favorable results may be related to the synergistic effect of hydroxyurea, cytarabine, and calcitriol.

Acute Disease↗
PubMed2006

t(3;21)(q26;q22) in myeloid leukemia: an aggressive syndrome of blast transformation associated with hydroxyurea or antimetabolite therapy.

BACKGROUND: The t(3;21)(q26;q22) translocation is associated with myeloid leukemias and results in a chimeric oncoprotein containing AML1/RUNX1 variably fused to EAP, MDS1, and/or EVI1. METHODS: The current study describes what to the authors' knowledge is the first large case series reported to date of 26 t(3;21)(q26;q22)-associated leukemias, in which 24 cases arose after chemotherapy. Conventional G-band karyotyping and flow cytometry immunophenotyping were performed. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect fusion transcripts between AML1 and EAP, MDS1, or EVI1, followed by DNA sequencing. RESULTS: In all 16 patients with chronic myeloproliferative disorders, including 14 with chronic myelogenous leukemia (CML), the occurrence of t(3;21) heralded myeloid blast transformation. Fifteen (93%) patients had been previously treated with hydroxyurea. Eight patients with chronic myeloproliferative disorders (CMPD) were found to have t(3;21) with t(9;22) as the sole cytogenetic abnormality; in 5 other patients this was accompanied by trisomy 8. Among 10 cases of t(3;21)-associated acute myeloid leukemia, 8 were secondary tumors after chemotherapy for other neoplasms that had been treated with regimens including fludarabine and 5-fluorouracil in 3 patients each and etoposide in 2 patients. The immunophenotype of the blasts in all 22 tested cases was similar, with uniform expression of myeloid markers and CD34 and variable expression of CD7 and CD9, but minimal morphological myeloid maturation. Dysplastic micromegakaryocytes and bone marrow fibrosis were observed predominantly in CMPD cases. RT-PCR followed by DNA sequencing showed that the AML1-/MDS1-/EVI1 (AME) fusion transcript was detected in all 5 cases assessed. Among the patients with CMPD, 8 died of disease (at a median of 6.5 mos) and 5 achieved disease remission with bone marrow transplantation. Among patients with acute myeloid leukemia/myelodysplastic syndrome, 7 died of disease (at a median of 2 mos) and 2 had persistent leukemia with short follow-up. CONCLUSIONS: Activation of AME through t(3;21) defines a highly aggressive, therapy-related leukemic blast syndrome. Prior treatment with hydroxyurea or other antimetabolites is implicated as a contributory cause.

Adult↗
PubMed1988

Effects of hydroxyurea parallel the effects of radiation in developing olfactory glomeruli in insects.

Previous observations (Oland and Tolbert: J. Comp. Neurol. 255:196-207, '87, Soc. Neurosci. Abstr. 13:1144, '87; Oland et al.: J. Neurosci. 8:353-367, '88) have provided evidence that the afferent-axon-induced development of synaptic glomeruli in the antennal lobe of the moth Manduca sexta depends upon an interaction between ingrowing sensory axons and the glial cells of the antennal lobe. In order to differentiate between the roles of glial cells and of afferent axons on the partitioning of the lobe into glomeruli, we have used the antimitotic agent hydroxyurea to produce lobes deficient in glial cells but retaining sensory input. The resulting lobes were analyzed in the light and electron microscopes, and the integrity of their antennal input was evaluated by examining the gross and microscopic structure of the antennae, the number of antennal afferent axons, and electroantennogram responses to odors. Our results with hydroxyurea show that in treated animals with adequate antennal input the degree to which the antennal-lobe neuropil becomes glomerular varies with the number of glial cells remaining in the lobe; when less than approximately one-quarter of the normal glial complement is present, glomeruli do not develop at all. These experiments complement and extend previous experiments in which the number of glial cells was reduced with radiation (Oland et al.: J. Neurosci. 8:353-367, '88). The fact that the present results mimic the previous results with radiation strongly suggest that glial cells do mediate the afferent-axon-induced formation of olfactory glomeruli in the moth.

Animals↗
PubMed1976

Solvent-dependent conformational system in hydroxyureas detected by NMR spectroscopy.

The proton magnetic resonance spectra of the antileukemia agent hydroxyurea and substituted hydroxyureas in several solvents were recorded and correlated with structural features. Solvent-dependent differences in conformational preferences due to effects on internal hydrogen bonding, a temperature-dependent conformational feature, anthe exchangeability of protons with deuterium oxide and acetone-d6 were observed. The conformational features consistent with the spectral data are discussed.

Chemical Phenomena↗
PubMed1986

Treatment of metastatic and recurrent cervix cancer with chemotherapy: a randomised trial comparing hydroxyurea with cisdiamminedichloro-platinum plus methotrexate.

In a randomised trial comparing single-agent chemotherapy (hydroxyurea) to combination chemotherapy in advanced cervix cancer, response was seen in 57% (including 13% CR) of patients receiving the combination (DDP + MTX) regimen. Responding patients survived significantly longer (11 months) than either those receiving hydroxyurea or those not responding to combination chemotherapy (4 months). Two patients remain in complete remission for 14+ and 17+ months.

Actuarial Analysis↗
PubMed1975

Comparative distribution and embryotoxicity of hydroxyurea in pregnant rats and rhesus monkeys.

Hydroxyurea was given to pregnant rhesus monkeys and pregnant rats in regimens adjusted to produce similar degrees of teratogenicity, for the purpose of comparing the distribution of the drug in the females and their embryos. According, in rats 137 mg/kg/day ip on days 9-12 resulted in a drug half-life in maternal plasma of about 15 min and in embryos about 85 min, after the last injection; and in monkeys 100 mg/kg/days iv on days 23-32 resulted in drug half-life in maternal plasma estimated to be 120 min and in embryos 265 min, after the last injection. Using as a baseline of biological effects the minimal concentration known to inhibit DNA synthesis in rat embryos and cancer cells, namely 10(-4) M, it was calculated that the rat embryos in the present study were exposed to this level or more for approximately 12 h whereas the monkey embryos were exposed for approximately 100 h. Although the teratogenic effects were not identical in the two species, these data are interpreted to mean that rat embryos are teratogenically much more sensitive to hydroxyurea than monkey embryos. These observations have important implications in the selection of appropriate species for tests to estimate human teratogenic risks. The rat, which is currently the most widely used animal for such tests, displays sizeable differences from rhesue monkeys, which is one of the animals thought to be most like man in teratogenic susceptibility.

Amniotic Fluid↗
PubMed2000

The subcellular location of nucleoside analog phosphorylation is a determinant of synergistic effects of hydroxyurea.

The ribonucleotide reductase inhibitor hydroxyurea exhibits synergistic pharmacological activity with several nucleoside analogs used in antiviral and anticancer chemotherapy. We have used a cell model system where a deoxycytidine kinase (dCK)-deficient cell line was reconstituted with genetically engineered dCK targeted to the cytosol, the nucleus, or the mitochondria to investigate how the subcellular location of nucleoside analog phosphorylation affected the synergistic effects of a ribonucleotide reductase inhibitor. Hydroxyurea showed synergistic cytotoxicity with the nucleoside analogs 1-beta-d-arabinofuranosylcytosine and 2-chloro-2'-deoxyadenosine when dCK was expressed in the cytosol or in the nucleus, but not when dCK was expressed in the mitochondria. These data indicate that the synergistic effect of ribonucleotide reductase inhibition is limited to nucleoside analogs phosphorylated in the cytosol or the cell nucleus.

Animals↗
PubMed1996

Phase II trial of hydroxyurea, dacarbazine (DTIC), and etoposide (VP-16) in mixed mesodermal tumors of the uterus: a Gynecologic Oncology Group study.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of this three-drug regimen--hydroxyurea, dacarbazine (DTIC), and etoposide (VP-16)--in patients with advanced or recurrent mixed mesodermal tumors (MMT) of the uterus who had not undergone previous chemotherapy. The study was performed as a groupwide phase II study of the Gynecologic Oncology Group. STUDY DESIGN: Thirty-three evaluable patients received hydroxyurea 2 g in divided doses on Day 1, 700 mg/m2 DTIC and 100 mg/m2 VP-16 on Day 2, and VP-16 100 mg/m2 on Days 3 and 4. Thirty-two patients were evaluable for response. Twenty-six patients had previously undergone abdominal hysterectomy and 11 had received prior radiation therapy, for whom one dose level reduction of the first course was required. RESULTS: Two patients exhibited complete response and three patients showed partial responses for an overall response rate of 15.7% (95% confidence interval: 5.3-32.8%). Seventeen of 32 patients had stable disease on therapy. Toxicity was acceptable and there were no treatment-related deaths. CONCLUSION: This regimen reveals moderate activity in patients with advanced or recurrent MMT.

Adult↗
PubMed1997

Hydroxyurea, 5-fluorouracil infusion, and cisplatin adjunct to radiation therapy in cervical carcinoma: a phase I-II trial of the Gynecologic Oncology Group.

BACKGROUND: In a previous study, the Gynecologic Oncology Group (GOG) compared hydroxyurea (HDXR) and the combination of cisplatin (C) and 5-fluorouracil (5-FU) infusion as potentiators of radiation therapy. This study was undertaken to determine whether these two regimens could be combined, concurrent with pelvic radiation therapy in patients with locally advanced cervical cancer. METHODS: The GOG entered 75 eligible and evaluable patients on a Phase I-II evaluation of HDXR, C, and 5-FU as adjuncts to radiation therapy for locally advanced carcinoma of the cervix. All patients had histologically verified primary disease and confirmed negative para-aortic lymph nodes. Eligibility was limited to clinical stage IIB through IVA. HDXR was given orally, twice weekly at a dose of 2.5 g/m2; C on Days 1 and 29 at 50 mg/m2; and 5-FU by 96-hr infusion on Days 2-5 and 30-33 at a starting dose of 800 mg/m2. RESULTS: Forty-eight (64%) patients had stage IIB disease, 25 (33%) had stage IIIB, and 2 had stage IVA tumors. Primary tumors 4 cm or less in size were present in 15 patients, between 4 and 6 cm were in 27 patients, and larger than 6-cm were observed in 33 patients. Grade 3/4 acute toxicity was experienced by 41 (54.7%) patients. These acute toxicities caused delays in prescribed radiation therapy of more than 1 week in 14 (18.9%) and low doses of drug in 16 (21.3%), and only 26 (34.7%) patients had the scheduled dose escalation of 5-FU on their second course. Clinical response was excellent with complete and partial response rate of 93.3%. Median time to progression has not been reached. CONCLUSION: Although this dose and schedule could be successfully administered, the delays in therapy should be avoided by a lower starting dose of hydroxyurea. Stomatitis was not a dose-limiting toxicity. These results have formed the basis of a phase III trial comparing this regimen to two other chemoradiation regimens.

Adult↗
PubMed1980

Therapy of solid Walker carcinosarcoma 256 with bleomycin after synchronization with hydroxyurea.

Rats with the solid Walker carcinosarcoma 256 were synchronized with hydroxyurea (6 x 50 mg/kg or 1 x 300 mg/kg body weight) and treated with bleomycin (32 mg/kg body weight) at different time points thereafter. Bleomycin clearly affects Walker carcinosarcoma cells at the G1/S boundary or in S-phase. The improvement in the results of bleomycin therapy after pretreatment with hydroxyurea can mainly be accounted for by the synchronization of the tumour cells.

Animals↗
PubMed1988

Phase 1 study of high-dose hydroxyurea in lung cancer.

The in vitro chemosensitivity of a human lung cancer cell line to hydroxyurea (HU) was measured, and concentrations of 1 mM HU effected 99% inhibition of cell growth. Therefore, infusions designed to achieve serum levels of over 1 mM HU were assessed by escalating doses of hydroxyurea (HU) administered by continuous i.v. infusion at 3-weekly intervals in 18 patients with lung cancer. Dose increments from 24 g in 24 h to 48 g in 48 h were achieved. The dose-limiting toxicity at 48 g in 48 h was myelosuppression. Oral administration of HU did not result in sustained levels comparable to those achieved with continuous infusion. Two patients showed evidence of radiological response after three courses of treatment. Serum HU profiles were monitored after administration i.v. in 26 courses and after administration p.o. in 5 courses of treatment. A mean serum level of greater than 1 mM was achieved by 6 h and then maintained during treatment. The standard error of the mean area under the curve showed an overall 5% variation. HU can be given in doses up to 48 g in 48 h 3-weekly with manageable tissue and bone marrow toxicity, and the in vivo blood levels attained are equal to those necessary for effective cell inhibition in an appropriate in vitro model. This schedule provides a basis for combination studies with other cytotoxics or for use of HU as a DNA repair inhibitor.

Aged↗
PubMed1988

Growth and macromolecular content of the dimorphic fungus Aureobasidium pullulans and the effect of hydroxyurea and other inhibitors.

The growth kinetics and the macromolecular content of the yeast and ethanol-induced hyphal forms of Aureobasidium pullulans were studied. During the morphological transition from yeasts to hyphae, both the protein and RNA content decreased significantly, the mycelial form containing only 76% of the amount of protein in the yeasts, and 38% of the RNA. The DNA was the only component tested whose level increased during the transition. Among several compounds inhibiting macromolecular synthesis, only hydroxyurea showed a remarkable effect on the morphology of A. pullulans, inducing the mycelial morphology. The macromolecular composition of hydroxyurea-treated cultures changed with time in a way similar to that of the ethanol-Tween 80-ammonia medium, and to that of carbon-starved cultures, without ethanol or glucose.

Culture Media↗
PubMed1993

Acute mucocutaneous toxicity following high-dose hydroxyurea.

Three patients with advanced acute myeloid leukemia were treated with oral high-dose hydroxyurea at a dose of 10 g daily for 8-10 days. Severe acute stomatitis developed in all three patients. In addition, two of the patients developed a peculiar acute cutaneous type of toxicity associated with soreness, violet erythema, and edema of the palms and foot soles followed by intense universal hyperpigmentation of the skin. Apparently, the pronounced acute mucocutaneous toxicity was caused by the sustained high daily dose of hydroxyurea, indicating that myelosuppression may not be the dose-limiting toxicity of this drug.

Acute Disease↗