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PubMed2024

Towards genomic medicine: a tailored next-generation sequencing panel for hydroxyurea pharmacogenomics in Tanzania.

BACKGROUND: Pharmacogenomics of hydroxyurea is an important aspect in the management of sickle cell disease (SCD), especially in the era of genomic medicine. Genetic variations in loci associated with HbF induction and drug metabolism are prime targets for hydroxyurea (HU) pharmacogenomics, as these can significantly impact the therapeutic efficacy and safety of HU in SCD patients. METHODS: This study involved designing of a custom panel targeting BCL11A, ARG2, HBB, HBG1, WAC, HBG2, HAO2, MYB, SAR1A, KLF10, CYP2C9, CYP2E1 and NOS1 as potential HU pharmacogenomics targets. These genes were selected based on their known roles in HbF induction and HU metabolism. The panel was designed using the Illumina Design Studio (Illumina, San Diego, CA, USA) and achieved a total coverage of 96% of all genomic targets over a span of 51.6 kilobases (kb). This custom panel was then sequenced using the Illumina MiSeq platform to ensure high coverage and accuracy. RESULTS: We are reporting a successfully designed Illumina (MiSeq) HU pharmacogenomics custom panel encompassing 51.6 kilobases. The designed panel achieved greater than 1000x amplicon coverage which is sufficient for genomic analysis. CONCLUSIONS: This study provides a valuable tool for research in HU pharmacogenomics, especially in Africa where SCD is highly prevalent, and personalized medicine approaches are crucial for improving patient outcomes. The custom-designed Illumina (MiSeq) panel, with its extensive coverage and high sequencing depth, provides a robust platform for studying genetic variations associated with HU response. This panel can contribute to the development of tailored therapeutic strategies, ultimately enhancing the management of SCD through more effective and safer use of hydroxyurea.

Hydroxyurea↗

PubMed1979

Production of nerveless Hydra attenuata by hydroxyurea treatments.

Hydroxyurea was used to produce hydra with varying nerve cell densities including a new type of nerveless animal. Hydra attenuata were treated with 10(-2) M hydroxyurea. By 23 days after treatment, 2 populations of animals are in culture. Both have a decrease in nerve cells. The first is a normal-coloured feeding animal (HU-R) and is recovering while the second is a pale non-feeding animal (HU-P). HU-P animals resemble nerveless animals in their lack of behavioural responses but they contain about 2% nerve cells. Upon hand feeding, some HU-P animals will recover but most will produce nerveless buds. Neverless hydra produced by hydroxyurea resemble nerveless animals produced by other techniques, in their behavioural, morphological and developmental properties. Normal animals, as cultured and in regeneration experiments, show a compact tentacle number distribution pattern with a small variance. Nerveless animals show broad tentacle distribution patterns with increased means and variances. It is suggested that a normal tentacle number regulatory mechanism is lacking or diminished in nerveless animals. This defect is correlated with hypostomal circumference and with nerve cells.

Animals↗

PubMed2000

Effects of chemotherapy (busulfan-hydroxyurea) and interferon-alfa on bone marrow morphologic features in chronic myelogenous leukemia. Histochemical and morphometric study on sequential trephine biopsy specimens with special emphasis on dynamic features.

We performed a retrospective clinicopathologic study on sequential biopsy specimens from 90 patients with Philadelphia chromosome-positive chronic myelogenous leukemia to study therapy-specific effects of busulfan (28 patients), hydroxyurea (32 patients), and interferon-alfa (IFN-alfa; 30 patients). Bone marrow specimens were evaluated by morphometry after silver impregnation and staining with monoclonal antibodies to identify reticulin fibers, nucleated erythroid precursors, megakaryocytes, and macrophages. To compute dynamics of histopathology implicating corresponding changes in time, relevant indices were calculated. Quantification of megakaryocytopoiesis and its precursor cell population showed a significant increase in the IFN-alfa and busulfan groups compared with the hydroxyurea group. These changes were associated with a development of myelofibrosis during therapy. Although a significant increase in fiber density was detectable in the busulfan group, the progression index proved to be twice as high after IFN-alfa therapy. In contrast, a considerable number of patients displayed a regression of myelofibrosis after hydroxyurea treatment. The general association of the megakaryocyte lineage with myelofibrosis was in line with experimental findings. The mature macrophage population and its activated subfraction revealed a marked proliferation (IFN-alfa group) during treatment. Growth and activation of macrophages may be compatible with their putative function during erythrocytopoietic regeneration and with stimulation of their phagocytic properties.

Antineoplastic Agents↗

PubMed1993

The German CML study, comparison of busulfan vs. hydroxyurea vs. interferon alpha and establishment of prognostic score 1.

From July 1983 to January 1991 a total of 622 patients were randomized (585 eligible) to compare the effects of hydroxyurea, interferon alpha (IFN), and busulfan on the duration of chronic phase, and survival. Further goals included the determination of prognostic parameters. 598 CML patients were documented and 575 evaluable. The Ph-status was known for 547 patients. 89.4% of the patients were Ph-positive (+). 11% had additional chromosome aberrations. The median survival of Ph+ patients by now is 4.2 years, that of Ph-patients 1.4 years. Ph-negative patients are older, tend to have lower cell counts and, as a group are more ill at diagnosis. A survival difference of about one year is expected between busulfan and hydroxyurea treated patients. Prospectively evaluated age, organomegaly related symptoms, Karnofsky index, extramedullary manifestations, number of erythroblasts and percent of circulating blasts proved to be of prognostic significance. A prognostic score (score 1) was determined which was superior to Sokal's score in the study population. 164 patients were randomized to receive IFN. In 54 patients (33%) IFN had to be terminated because of adverse effects, therapy resistance or other reasons. Clinically relevant neutralizing antibodies were detected in 9 cases. Most frequent adverse events were flu-like symptoms in 74%, gastrointestinal symptoms in 52%, and neurologic-psychiatric symptoms in 30% of patients. Reduction of the Ph-chromosome was observed in 13% of evaluable patients (10 of 75). In 4 patients complete cytogenetic remissions were observed, in three of these ongoing. Cytogenetic responders have a survival advantage. Interferon treated Philadelphia-negative CML patients have no survival disadvantage. The study is expected to allow statements as to the advantages or disadvantages of the use of busulfan, hydroxyurea and IFN in the treatment of CML as well as to the reliability of prognostic markers.

Adult↗

PubMed2006

Hydroxyurea induced perimalleolar ulcers.

Hydroxyurea (HU) is an antineoplastic drug commonly used to treat chronic myeloproliferative disorders. Common dermatological side effects include hyperpigmentation, scaling, erythema, alopecia, desquamation of face and hands. Leg ulceration following HU therapy is less common and very few cases have been reported so far. Objective of this paper is to increase the awareness of hydroxyurea induced leg ulcers which will aid in the early diagnosis and appropriate treatment. The first case was a chronic myeloid leukemia (CML) patient on HU 1.5 g/day for 5 yr, who had bilateral painful perimalleolar ulcers for 6 months. The second case was a CML patient on HU 1.5 g/day for 3 yr who developed bilateral lateral malleolar ulcers. Third case was a polycythemia vera (PV) patient on HU 1 g/day for 5 yr who presented with painful medial malleolar ulcer of 2 months. The last case of our report was an elderly PV patient on HU 1.5 g/day for 2 yr and presented with lateral malleolar ulcer which persisted on reducing the dose of HU. In all the 4 cases the ulcers healed on stopping HU. Our report confirms the association of chronic hydroxyurea therapy and perimalleolar ulcers which respond promptly after discontinuation of the drug. The heightened awareness among the physicians will promote early diagnosis and prompt relief from the agonizing ulcers.

Aged↗

PubMed1998

Multiple skin cancers associated with hydroxyurea therapy.

The association of multiple cutaneous cancers and long-term use of hydroxyurea is now being recognized. In this article, we describe the development of multiple skin tumors in two patients who were receiving hydroxyurea therapy. These cases illustrate the late onset of subsequent skin cancers despite discontinuation of therapy. As hydroxyurea continues to have a prominent role in the treatment of myeloproliferative diseases, clinicians must be aware of the increased risk of multiple skin cancers and use preventive and skin cancer screening practices in patients with these diseases.

Basal Cell Carcinoma↗

PubMed1999

[Hydroxyurea and other agents stimulating synthesis of fetal hemoglobin].

Five years after the initiation of the first clinical trials of hydroxyurea in pediatric sickle cell anemia patients, there is firm evidence that this drug induces a significant and sustained increase in fetal hemoglobin (HbF) production and decreases the frequency of vasoocclusive crises in the overwhelming majority of cases. The mean dosage associated with clinical benefits is 20 mg/kg/d; the HbF increase is not perfectly correlated with clinical benefits, so that a dosage increase should be considered based on the absence of a clinical improvement after three months. The daily dose should not exceed 40 g/kg. Short- and medium-term safety has been acceptable, with the few episodes of bone marrow toxicity resolving after dose attenuation or temporary drug discontinuation. Many issues remain unsettled, most notably the long-term safety of this cytostatic medication. Current knowledge gaps should be fully disclosed to parents, and hydroxyurea therapy should be reserved for patients with severe pain. Because no randomized placebo-controlled trials are available, the potential role for hydroxyurea as a preventive or curative treatment for other complications of sickle cell disease remains unknown.

Anemia, Sickle Cell↗

PubMed1999

Hydroxyurea-induced leg ulcers: is macroerythrocytosis a pathogenic factor?

Hydroxyurea is a common cancer chemotherapy agent that inhibits ribonucleotide reductase, an enzyme essential to DNA synthesis. It is considered the drug of choice in the treatment of chronic myelogenous leukemia and essential thrombocythemia. The occurrence of leg ulcers have been described in 8.5% of patients receiving continuous treatment with hydroxyurea, but the cause of this complication is unknown. We report two additional patients and suggest that macroerythrocytosis, which occurs in almost all the patients taking hydroxyurea, may be a pathogenic factor. Macroerythrocytosis can be considered as an 'acquired' blood dyscrasia, and similar leg ulcers have long been known to occur with certain hereditary blood dyscrasias, such as sickle cell anemia, thalasemia, and spherocytosis.

Animals↗

PubMed2000

[beta-thalassemia minor diagnosed in a patient with chronic myelogenous leukemia during hydroxyurea therapy].

A 55-year-old man was admitted to our hospital because of leukocytosis and microcytic anemia with hypochromia, target cells, and increased levels of hemoglobin A2 and hemoglobin F. The results of a gene analysis yielded a diagnosis of chronic myelogenous leukemia and beta-thalassemia minor. A gradual increase in hemoglobin was observed during hydroxyurea therapy, which was performed over a 12-week period. This increment appeared to be due to suppressed production of myeloid cells. It was been reported that hydroxyurea increases total hemoglobin due to increased hemoglobin F synthesis in patients with beta-thalassemia. However, hydroxyurea had no clear influence on hemoglobin concentration in this case.

Antineoplastic Agents↗

PubMed1999

[Leukemic transformation of polycythemia vera after treatment with hydroxyurea and chromosome 17 abnormalities].

The authors present two patients with polycythemia vera where they recorded after several years' treatment with hydroxyurea development of acute myeloblastic leukaemia. In both instances they found, associated with leukaemia, abnormalities of chromosome no.17, in one case meeting criteria of the so-called 17p-syndrome. Progression of polycythemia vera into acute leukaemia is explained by the possible association with the long-term use of the drug and loss of chromosomal material (short arm of chromosome 17), the part where genes important in the process of leukaemogenesis are located. The authors draw attention to contemplated long-term administration of hydroxyurea to young patients with polycythemia vera. As cytogenetic analysis is a suitable method for evidence of progressing polycythemia vera into acute leukaemia, dynamic follow up of chromosomal changes is necessary, in particular in patients where long-term treatment with hydroxyurea is assumed.

Chromosome Deletion↗

PubMed2000

Hydroxyurea induced leg ulcers.

A 34 years non diabetic lady with chronic myeloid leukaemia (CML) was treated with hydroxyurea and interferon. She developed leg ulcers. First time on left toe and three months later on right foot, a rare complication of hydroxyurea. Both were treated with local wound care and antibiotics. First time dose of hydroxyurea was reduced and second time drug was discontinued.

Adult↗

PubMed1975

[Incorporation of a 131-iodine-deoxycytidine monophosphate protamine complex into the DNA of tumor-bearing rats following partial synchronization with hydroxyurea].

The incorporation of 131-Iodo-deoxyuridine in rat tumours can be increased by partial synchronisation with hydroxyurea. The reported investigation was carried out to determine whether the incorporation could be further increased by using a basic 131-Iodo-deoxycytidine-monophosphate-protamine complex as a depot of Iodo-deoxyuridine. It was shown that the incorporation observed after synchronisation could be increased by using this complex (non-synchronized tumours 1,46% retention, synchronized tumours 2,28% retention; measured 4 hour after the final injection of hydroxyurea) whereas in a control group injected with 131-Iodo-deoxycytidine-monophosphate alone, only a small increase was observed. The large increase in activity in the liver and in the spleen (liver: non-synchronized 2,76%, synchronized 2,79% retention; spleen: non-synchronized 3,00, synchronized 3,80% retention; measured 4 hours after final injection of hydroxyurea) which is observed after injection of the 131-Iodo-deoxycytidine-monophosphate-protamine complex renders it unsuitable for use in the scintigraphic detection of tumours. 131-Iodo-deoxyuridine is shown to be more suitable for this purpose.

Animals↗

PubMed1998

[Drug-induced fever caused by hydroxyurea. Apropos of 3 new cases].

Drug-induced fever is a frequent (3-5% of all adverse effects) but under recognized adverse effect of several drugs. Hydroxyurea, an antimetabolite cytostatic agent, has rarely been involved in the occurrence of fever. We report three additional cases of hydroxyurea-induced fever including one case with pulmonary involvement (acute alveolitis). In these cases, the role of hydroxyurea was strongly suggested by the delay to onset of symptoms (16-36 days), the disappearance of fever within a few hours after drug withdrawal, the recurrence of fever shortly after rechallenge in two patients, and the absence of any other obvious cause.

Aged↗

PubMed2002

Myelofibrosis: response to busulfan after hydroxyurea failure.

We report a case of myelofibrosis with myeloid metaplasia (MMM) that responded dramatically to oral busulfan treatment after failure of hydroxyurea. Although busulfan treatment of this disease has fallen out of favour due to the favourable toxicity profile of hydroxyurea and reports of efficacy of interferon-alpha, our observation suggests there may still be a role for busulfan treatment of MMM in the setting of hydroxyurea or interferon failure or intolerance.

Alkylating Agents↗

PubMedDate not supplied

Determination of hydroxyurea in capsules and biological fluids by ion-selective potentiometry and fluorimetry.

Two hydroxyurea selective electrodes were investigated with beta-cyclodextrin used as ionophore and either tetrakis (p-chlorophenyl) borate (electrode 1), or tetrakis [3,4-bis (trifluoromethyl) phenyl] borate (electrode 2), as a fixed anionic site in a polymeric matrix of carboxylated polyvinyl chloride. Linear responses of hydroxyurea within a concentration range of 10(-5)-10(-)3 M with slopes of 51.2 and 58.6 mV/decade with pH 3-6 were obtained by using electrodes 1 and 2, respectively. Two spectrofluorimetric methods involving the formation of drug-AI(III) complex (method 3) and drug-Mg(II) complex (method 4) at pH 5 were also investigated. These complexes emit fluorescence at wavelengths of 380 and 355 nm, after excitation at 305 nm, for AI and Mg complexes, respectively. The calibration graphs were rectilinear from 0.5 to 2.5 microg/mL for the AI complex and 1 to 5 microg/mL for the Mg complex. The 4 proposed methods display useful analytical characteristics for determination of hydroxyurea, with average recoveries of 100.2 +/- 0.83 and 99.4 +/- 1.81% in capsules and 99.7 +/- 0.70 and 99.4 +/- 1.25% in biological fluids for the potentiometric and fluorimetric methods, respectively. Results obtained by the proposed procedures were statistically analyzed and compared with those obtained by the U.S. Pharmacopeial method. The 4 proposed procedures were also used to determine the stability of the drug in the presence of its degradate, hydroxylamine.

Aluminum↗

PubMed1982

Phenobarbital-induced alterations in the sexual differentiation of the female rat: reversal by hydroxyurea and cycloheximide.

The possible mechanism of action of phenobarbital in prenatal female rats has been studied using different inhibitors of protein/DNA/RNA synthesis. Administration of phenobarbital (40 mg/kg/day) subcutaneously from day 17 to day 20 of pregnancy resulted in a delay of the onset of puberty, disorders of estrous cycle, infertility, and high estrogen levels in the female offspring. Cycloheximide (60 microg/kg/day)--a protein synthesis inhibitor and hydroxyurea (160 mg/kg/day)--a DNA synthesis inhibitor when combined with phenobarbital, significantly reduced the incidence of reproductive dysfunctions listed above. Alpha-amanitin (15 microg/kg/day), an inhibitor of m-RNA synthesis, produced reproductive disorders in the female offspring when administered alone to pregnant rats and also failed to reverse the PB-induced reproductive alterations. Cycloheximide and hydroxyurea produced no effect upon reproductive function when administered alone. Cycloheximide administration resulted in low body weight at birth and delayed eye opening. These results suggest that prenatal administration of phenobarbital produces its effect via new protein synthesis and that cycloheximide and hydroxyurea protect the offspring from phenobarbital-induced toxic effects by inhibiting its biochemical action.

Animals↗

PubMed1992

Hydroxyurea: effects on hemoglobin F production in patients with sickle cell anemia.

Patients with sickle cell anemia were treated with daily doses of hydroxyurea, to assess pharmacokinetics, toxicity, and increase in fetal hemoglobin (Hb) production in response to the drug. Plasma hydroxyurea clearances were not a useful guide to maximum tolerated doses of the drug. The mean daily single oral dose that could be maintained for at least 16 weeks was 21 mg/kg (range, 10 to 35 mg/kg). Among 32 patients, last HbF levels were 1.9% to 26.3% (mean, 14.9%) with increases in HbF over initial values of 1.4% to 20.2% (mean, 11.2%). The most significant predictors of last HbF were last plasma hydroxyurea level, initial white blood count and initial HbF concentration. Last HbF was not related to beta globin haplotype or alpha globin gene number. No serious toxicity was encountered. Clinically significant bone marrow depression was avoided, and chromosome abnormalities after 2 years of treatment were no greater than those observed before treatment. The period of observation has been too short to evaluate the risk of carcinogenesis. Patient's red cells developed striking macrocytosis. Median red cell Hb concentrations did not change. Hb concentrations increased, on average 1.2 g/dL, but serum erythropoietin levels increased. Patients' body weights increased, and some returned to work or school, but no conclusions regarding therapeutic efficacy could be drawn from this uncontrolled open-label study.

Adult↗

PubMed2004

[Severe hyponatremia with consciousness disturbance caused by hydroxyurea in a patient with chronic myeloid leukemia].

A 79-year-old man was admitted because of consciousness disturbance on August 9, 2002. He had been diagnosed as having chronic myeloid leukemia in 1999, and since then, he had continued to take hydroxyurea (1500 mg/day) orally. On admission, his serum sodium concentration was as low as 119 mEq/L, while urinary sodium excretion was high. Based on the blood picture and lack of hepatosplenomegaly, we considered that the leukemia was still in the chronic phase. Because of normal blood level of the antidiuretic hormone (ADH) concentration and sufficient urine volume, the syndrome of inappropriate ADH secretion (SIADH) was unlikely, and sodium-losing nephropathy was suspected. After discontinuation of hydroxyurea, the urinary sodium excretion decreased and the patient's consciousness became clear concomitantly with improvement in the serum Na level. This patient appears to be the first case of hyponatremia caused by hydroxyurea.

Aged↗