Clinical response and adverse events in young patients with sickle cell disease treated with hydroxyurea

The authors studied the long-term clinical and hematological response to hydroxyurea (HU) therapy in young patients, with either S/β-thalassemia (β^thal) (8 patients) or SS (6 patients). All patients with S/β^thal responded well to treatment. Longitudinal evaluation of Hb, HbF, and MCV showed a significant increase compared to baseline levels, but the pattern of HbF changes varied among patients. Changes in HbF and Hb correlated well with baseline HbF. Favorable clinical responses, as documented by decline in hospitalization days for vasoocclusive crisis and transfused units of packed red blood cells, were also noted. During treatment, 1 patient was diagnosed with Hodgkin's lymphoma and 2 patients developed bilateral avascular necrosis of the femoral head. HU seems to be effective in a high proportion of young patients with sickle cell disease and in particular with S/β^thal, but cannot eliminate occurrence of serious adverse events.     

Combined treatment of psoriasis with etretinate plus hydroxyurea

Nineteen patients with extensive, therapy-resistant psoriasis received combined treatment with etretinate plus hydroxyurea. The individual components were given at a reduced dosage and hydroxyurea was administered intermittently. During 12 weeks of treatment, complete remission or marked improvement was observed in 16 patients (84%). The combination of etretinate and hydroxyurea in the above-mentioned regimen was both effective and well-tolerated.     

Therapeutic response of leukemic mice treated with fluorinated pyrimidines and inhibitors of deoxyuridylate synthesis

The therapeutic efficacy of combinations of fluorinated pyrimidines and inhibitors of either ribonucleotide reductase or deoxycytidylate deaminase was evaluated for the treatment of the L1210 mouse leukemia in DBA/2 mice. Therapeutic synergisms were observed with optimal combinations of 5-fluor-2'-deoxyuridine and either hydroxyurea or guanazole. In addition, mice treated with guanazole combined with 5-fluorouracil survived longer than was observed with any dose of guanazole or with 5-fluorouracil alone. Tetrahydrodeoxyuridine, a potential prodrug of a transition-state analog of deoxycytidylate deaminase, did not have antitumor activity by itself nor did it improve the therapeutic response of leukemic mice to 5-fluoro-2'-deoxyuridine. These results are consistent with the hypothesis that deoxyuridylate accumulation was limited by inhibition of ribonucleotide reductase but not by administration of tetrahydrodeoxyuridine. It is suggested that combination chemotherapy with fluorinated pyrimidines and inhibitors of deoxyuridylate synthesis may improve the therapeutic response to these drugs.     

Estrogen-induced prolactin and DNA synthesis in immature female rat pituitaries.

Estradiol is likely involved in stimulating developmental changes in the ability of the rat pituitary to secrete prolactin. To investigate the possibility that these changes involve proliferation of prolactin cells, estradiol effects on pituitary growth and prolactin synthesis were examined. Estradiol treatment of immature female rats stimulates increases in pituitary weight, [3H] thymidine incorporation, DNA content and prolactin synthesis. Treatment of rats with the DNA synthesis inhibitor, hydroxyurea, partially blocked the ability of estradiol to stimulate prolactin synthesis suggesting that at least part of the effect of estrogen is due to cell proliferation. These results suggest that estrogen-induced proliferation of prolactin cells is involved in the developmental processes of the pituitary.     

Evaluation of a procaspase-3 activator with hydroxyurea or temozolomide against high-grade meningioma in cell culture and canine cancer patients

BackgroundHigh-grade meningioma is an aggressive type of brain cancer that is often recalcitrant to surgery and radiotherapy, leading to poor overall survival. Currently, there are no FDA-approved drugs for meningioma, highlighting the need for new therapeutic options, but development is challenging due to the lack of predictive preclinical models.MethodsTo leverage the known overexpression of procaspase-3 in meningioma, PAC-1, a blood-brain barrier penetrant procaspase-3 activator, was evaluated for its ability to induce apoptosis in meningioma cells. To enhance the effects of PAC-1, combinations with either hydroxyurea or temozolomide were explored in cell culture. Both combinations were further investigated in small groups of canine meningioma patients and assessed by MRI, and the novel apoptosis tracer, [¹⁸F]C-SNAT4, was evaluated in patients treated with PAC-1 + HU.ResultsIn meningioma cell lines in culture, PAC-1 + HU are synergistic while PAC-1 + TMZ show additive-to-synergistic effects. In canine meningioma patients, PAC-1 + HU led to stabilization of disease and no change in apoptosis within the tumor, whereas PAC-1 + TMZ reduced tumor burden in all three canine patients treated.ConclusionsOur results suggest PAC-1 + TMZ as a potentially efficacious combination for the treatment of human meningioma, and also demonstrate the utility of including pet dogs with meningioma as a means to assess anticancer strategies for this common brain tumor.     

Comparison of four different treatment conditions of extended exposure in the in vitro micronucleus assay using TK6 lymphoblastoid cells

In the OECD Guideline 487, a total of four extended exposure treatment conditions are proposed for the in vitro micronucleus (MNvit) assay in the presence and absence of a cytokinesis block and with or without a recovery period. This guideline also states that rodent cell lines and human lymphocytes can be used as shown by many validated studies but that human cell lines such as TK6 and HepG2 are not yet validated. In this present study each extended exposure condition was characterized by investigation using TK6 cells and nine chemicals known to be able to induce micronucleus (MN) in rodent cell lines. The results revealed two concerns: six chemicals did not show significant MN induction in the ‘cytokinesis block without recovery period’; two aneugens showed no dose-dependent cytotoxicity in the ‘cytokinesis block with recovery period’. Further investigation revealed that 3–4 times higher spontaneous MN frequency than that in the other conditions is a possible reason for the low sensitivity, and this high spontaneous MN frequency was not observed in Chinese hamster lung cells under the identical treatment condition. With regard to the two conditions without cytokinesis block, two negative substances were evaluated and found to be negative, suggesting the validity of the TK6 test system for these conditions. Although our findings showed a few concerns for the treatment with cytokinesis block, the TK6 cells were considered to be a reliable cell line to be used for detecting potential inducers of MN in the in vitro micronucleus assay based on the overall results.     

Fetal haemoglobin augmentation in E/beta(0) thalassaemia: clinical and haematological outcome

Patients with E/beta(0) thalassaemia, the most common haemoglobinopathy in many Asian countries, might benefit from drugs that increase fetal and total haemoglobin and thereby decrease the need for transfusions. The long-term clinical efficacy and safety of such therapy is unknown, limiting its use in countries where resources for safe and regular transfusion are scarce. In this study, 45 patients were treated with hydroxyurea (18-20 mg/kg) for 24+/-9 months, hydroxyurea with sodium phenyl butyrate (n=8) and hydroxyurea with erythropoietin (n=9), each for approximately 6 months, and followed for 3 years from study exit. Hydroxyurea had minimal toxicity, resulted in a mean 1.3 g/dl steady-state increase in haemoglobin in 40% of patients, and a milder response (hydroxyurea. Hydroxyurea moderately increased steady-state haemoglobin in a sub-group of E/beta(0) thalassaemia patients and can be considered for patients with intermediate severity disease, thus delaying or avoiding the need for life-long transfusions. Continuous monitoring of toxicity and growth is required.     

Hydroxyurea therapy in paraparesis and cauda equina syndrome due to extramedullary haematopoiesis in thalassaemia: improvement of clinical and haematological parameters

Patients with beta-globin disorders show amelioration of clinical condition by sustained synthesis of fetal haemoglobin in adult life. We report data on a patient with beta(o)-thalassaemia genotype and thalassaemia intermedia clinical phenotype. He received therapy with hydroxyurea (20 mg/kg/d) because of the presence of extramedullary masses causing paraparesis, neurogenic bladder and impotence. During therapy, the patient showed an improved clinical picture and a significant increase in total Hb (from 71.8 to 103.2 g/L) and a gamma/alpha globin synthetic ratio (from 0.39 to 0.68). The myelosuppressive effect of hydroxyurea was revealed by a decrease in CFU-GEMM, BFU-E, and CFU-GM. Therefore hydroxyurea can be effective in the treatment of patients with extramedullary haematopoiesis (EMH) who are not transfusion-dependent and cannot be treated with radiotherapy.