Optimal treatment of opioid induced constipation in daily clinical practice - an observational study.

BACKGROUND: Opioids are prescribed in over 40% of patients with advanced cancer, but side effects occur frequently. In this study we evaluated the development and treatment of opioid induced constipation (OIC), and OIC resolving effect of methylnaltrexone for different opioid subtypes in daily clinical practice. METHODS: Patients with cancer using opioids were included in a retrospective chart analysis. Baseline characteristics, data on opioid use, laxative use, and OIC were collected. Patients with OIC who were prescribed methylnaltrexone, were included in a prospective observational trial (NCT01955213). RESULTS: Thirty-nine of 327 patients (pts) with cancer who were treated with opioids suffered from OIC (overall prevalence 12%; 95%-CI: 8-15%). The prevalence of OIC was similar in patients treated with oxycodone or fentanyl (12 of 81 pts. vs. 18 of 110 pts., RR 0.9; 95%CI 0.4-2.0). The morphine equivalent daily dose did not significantly differ between opioid subtypes (fentanyl 89 mg (IQR 60-180) vs. oxycodone 40 mg (40-80), P = 0.231). Twenty-two individual patients (7%) were admitted for OIC. Most effective laxatives in admitted patients were enemas, methylnaltrexone, or 4-l polyethylene-glycol solution. In the prospective observational study, the effect of methylnaltrexone could be evaluated in 23 patients. Eleven patients achieved the primary endpoint of ≥2 laxation responses out of the first four doses methylnaltrexone, independent of opioid subtype. CONCLUSIONS: OIC is a burdensome clinical problem independent of opioid subtype. Timely intensification of prophylactic laxative treatment, especially when opioid doses increase, may help to prevent OIC. Clinically overt OIC requires a more intensive laxative regimen with for example methylnaltrexone. TRIAL REGISTRATION: NCT01955213 .

High-Dose Chemotherapy and Blood Autologous Stem-Cell Rescue Compared With Standard Chemotherapy in Localized High-Risk Ewing Sarcoma: Results of Euro-E.W.I.N.G.99 and Ewing-2008.

Purpose For over 30 years, the place of consolidation high-dose chemotherapy in Ewing sarcoma (ES) has been controversial. A randomized study was conducted to determine whether consolidation high-dose chemotherapy improved survival in patients with localized ES at high risk for relapse. Methods Randomization between busulfan and melphalan (BuMel) or standard chemotherapy (vincristine, dactinomycin, and ifosfamide [VAI], seven courses) was offered to patients if they were younger than 50 years of age with poor histologic response (≥ 10% viable cells) after receiving vincristine, ifosfamide, doxorubicin, and etoposide (six courses); or had a tumor volume at diagnosis ≥ 200 mL if unresected, or initially resected, or resected after radiotherapy. A 15% improvement in 3-year event-free survival (EFS) was sought (hazard ratio [HR], 0.60). Results Between 2000 and 2015, 240 patients classified as high risk (median age, 17.1 years) were randomly assigned to VAI (n = 118) or BuMel (n = 122). Seventy-eight percent entered the trial because of poor histologic response after chemotherapy alone. Median follow-up was 7.8 years. In an intent-to-treat analysis, the risk of event was significantly decreased by BuMel compared with VAI: HR, 0.64 (95% CI, 0.43 to 0.95; P = .026); 3- and 8-year EFS were, respectively, 69.0% (95% CI, 60.2% to 76.6%) versus 56.7% (95% CI, 47.6% to 65.4%) and 60.7% (95% CI, 51.1% to 69.6%) versus 47.1% (95% CI, 37.7% to 56.8%). Overall survival (OS) also favored BuMel: HR, 0.63 (95% CI, 0.41 to 0.95; P = .028); 3- and 8-year OS were, respectively, 78.0% (95% CI, 69.6% to 84.5%) versus 72.2% (95% CI, 63.3% to 79.6%) and 64.5% (95% CI, 54.4% to 73.5%) versus 55.6% (95% CI, 45.8% to 65.1%). Results were consistent in the sensitivity analysis. Two patients died as a result of BuMel-related toxicity, one after standard chemotherapy. Significantly more BuMel patients experienced severe acute toxicities from this course of chemotherapy compared with multiple VAI courses. Conclusion BuMel improved EFS and OS when given after vincristine, ifosfamide, doxorubicin, and etoposide induction in localized ES with predefined high-risk factors. For this group of patients, BuMel may be an important addition to the standard of care.

Prognostic parameters for response to enzalutamide after docetaxel and abiraterone treatment in metastatic castration-resistant prostate cancer patients; a possible time relation.

BACKGROUND: Abiraterone Acetate (AA) and Enzalutamide (Enz) are effective hormonal treatments in mCRPC patients. Retrospective studies suggested clinical cross-resistance between Enz and AA. However, 12.8-39.1% of patients previously treated with docetaxel (Doc) and AA do respond to Enz. These responders have not been characterized. METHODS: 102 Enz treated mCRPC patients after AA and Doc treatment were included in this study. Differences in patient characteristics and previous treatment outcomes between PSA responders and non-responders on Enz were evaluated. RESULTS: Median Progression-Free Survival was 12.2 weeks (95%CI 11.7-14.3) and Overall Survival 43.5 weeks (95%CI 37.4-61.2). There were 26 (25%) Enz-responders and 76 (75%) non-responders. Significant higher percentages of Gleason scores ≥ 8 and PSA doubling times (PSA-DT) <3 months were found in Enz responders than in non-responders. The interval between end of AA and start of Enz treatment (IAE) for responders was 24.6 weeks (IQR 4.0-48.1) and 8.9 weeks for non-responders (IQR 3.7-25.9) (P = 0.08). In an IAE <40 days subgroup (34 patients), Enz responses were related to AA non-responsiveness, while univariate and logistic regression analysis of baseline criteria of a subgroup of patients with an IAE ≥ 40 (68 patients) revealed significant differences in baseline PSA levels, PSA-DT <3 months, Gleason scores ≥ 8 and IAE's between Enz responders and non-responders. CONCLUSIONS: PSA response to Enz after previous AA and Doc treatment was associated with a longer IAE, a higher Gleason score and a PSA-DT <3 months. Identification of these patients might be of value for sequencing of treatment options.

Ewing Sarcoma: Current Management and Future Approaches Through Collaboration.

Ewing sarcoma (ES) is an aggressive sarcoma of bone and soft tissue occurring at any age with a peak incidence in adolescents and young adults. The treatment of ES relies on a multidisciplinary approach, coupling risk-adapted intensive neoadjuvant and adjuvant chemotherapies with surgery and/or radiotherapy for control of the primary site and possible metastatic disease. The optimization of ES multimodality therapeutic strategies has resulted from the efforts of several national and international groups in Europe and North America and from cooperation between pediatric and medical oncologists. Successive first-line trials addressed the efficacy of various cyclic combinations of drugs incorporating doxorubicin, vincristine, cyclophosphamide, ifosfamide, etoposide, and dactinomycin and identified prognostic factors now used to tailor therapies. The role of high-dose chemotherapy is still debated. Current 5-year overall survival for patients with localized disease is 65% to 75%. Patients with metastases have a 5-year overall survival < 30%, except for those with isolated pulmonary metastasis (approximately 50%). Patients with recurrence have a dismal prognosis. The many insights into the biology of the EWS-FLI1 protein in the initiation and progression of ES remain to be translated into novel therapeutic strategies. Current options and future approaches will be discussed.

Clinical evaluation of the efficacy of methylnaltrexone in resolving constipation induced by different opioid subtypes combined with laboratory analysis of immunomodulatory and antiangiogenic effects of methylnaltrexone.

BACKGROUND: Opioid-induced constipation (OIC) is one of the major symptoms in palliative care with a prevalence of 30-50%. Methylnaltrexone for the treatment of OIC is significantly more effective than placebo, but only in about fifty percent of the patients regardless of dose increase. Dose increases cause increased toxicity without additional efficacy, and are therefore not recommended. While methylnaltrexone is a µ-receptor antagonist, only a few opioids are solely µ-receptor agonists. Therefore, the response to methylnaltrexone may be determined by the receptor-profile of a specific opioid. In addition, methylnaltrexone may also affect the immune system and angiogenesis as was found in pre-clinical studies. Primary aim of this study is to determine differences in the efficacy of methylnaltrexone prescribed to resolve opioid induced constipation between three commonly used opioid subtypes: morphine sulphate, oxycodone and fentanyl. Secondary aim is to explore potential immunomodulatory and antiangiogenic effects of methylnaltrexone. METHODS: In this multi-center, prospective, parallel group trial we will evaluate the efficacy of methylnaltrexone in resolving OIC occurring as a side effect of the most common opioid subtypes: morphine, oxycodone and fentanyl. In total 195 patients with OIC despite prophylactic laxatives will receive methylnaltrexone every other day up to fourteen days. Patients will report its effect in a laxation diary. Group allocation is based on the opioid type the patient is using. At the start and end of the study period patients complete the Bowel Function Index questionnaire. A subgroup of the patients will donate blood for analysis of immunomodulatory- and anti-angiogenic effects of methylnaltrexone. DISCUSSION: In this study we aim to determine the efficacy of methylnaltrexone per opioid subtype to reduce constipation. We expect that the outcome of this study will improve the clinical use of methylnaltraxone. TRIAL REGISTRATION: This trial is registered at clinicaltrials.gov: NCT01955213 and in the Dutch trial register: NTR4272.

Cytostatic drugs in infants: a review on pharmacokinetic data in infants.

Below a certain age protocols in pediatric oncology on cytostatic drug therapy advise use, of other parameters such as weight for dosing; this instead of the most conventional parameter, i.e. body surface area. In infants it is not uncommon that additional reductions are put on top of this for each cytostatic drugs to be administered. The rationale behind this is often lacking. Differences related to the ontogeny of absorption, distribution, metabolism and excretion are often not mentioned. Considering characteristics, such as lipophilia, ionization in relation to pH and size of the molecule and linking these characteristics with age related shifts in the gastrointestinal tract, composition of the body and renal function; predictions on pharmacokinetics (PK) in these infants can to a certain extent be made. More difficult are the shifts in activity of phase I and II enzymes, which are often not known for a specific product. In this review data on the ontogeny of relevant pharmacokinetic pathways in relation to the various cytostatic drugs and data from pharmacokinetic (PK) studies in infants are presented. This review shows that the administration of cytostatic drugs in infants is often based on limited or even no data at all. Based on such a lack of evidence on treatment of infants with cancer; it should be mandatory that in each infant treated with cytostatic drugs pharmacokinetic data are collected. Compiling these data in a global database would enable evidence-based drug therapy in infants with malignancies, resulting in a more effective treatment with less toxicity in this vulnerable population.

Growth inhibitory activity of extracted material and isolated compounds from the fruits of Kigelia pinnata.

A study of the components of the fruits of Kigelia pinnata was undertaken to identify compounds with potential growth inhibitory activity against human melanoma cells, since extracts from the fruits of this plant have been described in traditional medicine to have application in the treatment of skin cancer and other skin ailments. A bioactivity-guided fractionation process yielded a number of crude fractions, which demonstrated cytotoxicity in vitro against human melanoma cells. Compounds isolated and identified included the isocoumarins, demethylkigelin (1) and kigelin (2), fatty acids, oleic (3) and heneicosanoic acids (4), the furonaphthoquinone, 2-(1-hydroxyethyl)-naphtho[2,3-b]furan-4,9-dione (5), and ferulic acid (6). A number of structurally related synthetic compounds were also tested using the MTT assay. The most potent series of these compounds, the furonaphthoquinones, also demonstrated a cytotoxic effect in two human breast cancer cell lines tested.

Different mechanisms regulate CD4(+) T cell independent induction of oral and nasal tolerance of CD8(+) T cells.

Mucosal administration of antigens is known to induce antigen specific regulatory CD4(+) T cells, but less is known about the effects on CD8(+) T cell function. Using a murine model for mucosal tolerance induction, we show that both oral and nasal OVA (ovalbumin) application reduced OVA specific CD8(+) T effector cell numbers and suppressed in vivo cytotoxicity in response to subsequent immunisation. To investigate whether CD4(+) T cells are essential for oral or nasal CD8(+) T cell tolerance, we used MHC class II deficient mice. Normal CD8(+) T cell tolerance was observed in MHC class II deficient mice, indicating that CD4(+) T cells are not required for both oral and nasal CD8(+) T cell tolerance induction. To study the direct effects of mucosal antigen application on naive CD8(+) T cells, we adoptively transferred OVA specific transgenic CD8(+) T cells and analysed their fate after mucosal antigen application. Oral OVA application reduced the numbers of OVA specific CD8(+) T cells, whereas nasal OVA application induced proliferation. However, the expanded population of OVA specific CD8(+) T cells from nasally treated mice was unable to proliferate upon re-stimulation. In conclusion, our studies point to suppressive effects of the mucosal immune system directly on CD8(+) T cells and indicate multiple mechanisms of tolerance induction. More insight in these mechanisms of tolerance induction is necessary for the development of mucosal tolerance therapies for autoimmune diseases and allergy.

Breast cancer risk in female survivors of Hodgkin's lymphoma: lower risk after smaller radiation volumes.

PURPOSE: We assessed the long-term risk of breast cancer (BC) after treatment for Hodgkin's lymphoma (HL). We focused on the volume of breast tissue exposed to radiation and the influence of gonadotoxic chemotherapy (CT). PATIENTS AND METHODS: We performed a cohort study among 1,122 female 5-year survivors treated for HL before the age of 51 years between 1965 and 1995. We compared the incidence of BC with that in the general population. To assess the risk according to radiation volume and hormone factors, we performed multivariate Cox regression analyses. RESULTS: After a median follow-up of 17.8 years, 120 women developed BC (standardized incidence ratio [SIR], 5.6; 95% CI, 4.6 to 6.8), absolute excess risk 57 per 10,000 patients per year. The overall cumulative incidence 30 years after treatment was 19% (95% CI, 16% to 23%); for those treated before age 21 years, it was 26% (95% CI, 19% to 33%). The relative risk remained high after prolonged follow-up (> 30 years after treatment: SIR, 9.5; 95% CI, 4.9 to 16.6). Mantle field irradiation (involving the axillary, mediastinal, and neck nodes) was associated with a 2.7-fold increased risk (95% CI, 1.1 to 6.9) compared with similarly dosed (36 to 44 Gy) mediastinal irradiation alone. Women with >or= 20 years of intact ovarian function after radiotherapy at young ages (< 31 years) experienced significantly higher risks for BC than those with fewer than 10 years of intact ovarian function. CONCLUSION: Reduction of radiation volume appears to decrease the risk for BC after HL. In addition, shorter duration of intact ovarian function after irradiation is associated with a significant reduction of the risk for BC.

Synthesis and in vitro and in vivo evaluation of a series of dihydroisocoumarin derivatives conjugated with fatty acids, alcohols, and amines as potential anticancer agents.

In this paper, we report the synthesis and biological activity of a series of dihydroisocoumarin analogues conjugated with fatty acids, alcohols, or amines, of varying hydrocarbon chain length and degree of unsaturation, to the dihydroisocoumarins, kigelin and mellein, at the C-7 and C-8 positions on the core dihydroisocoumarin structure. These compounds were evaluated for their antiproliferative activity against human breast cancer (MCF-7 and MDA-MB-468) and melanoma cells (SK-MEL-28 and Malme-3M) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Two compounds conjugated with gamma-linolenyl alcohol (18:3 n-6) demonstrated potent antiproliferative activity in vitro with one of these 4-hydroxy-3-oxo-1,3-dihydro-isobenzofuran-5-carboxylic acid octadeca-6,9,12-trienyl ester, demonstrating significant antitumor activity in vivo in a number of human tumor xenograft models.

Extra-osseous Ewing sarcoma.

BACKGROUND: Clinical data and data on outcome of extra-osseous Ewing tumors are scarce. PROCEDURE: After a search for Ewing tumors in the database of a single institution over a period of 20 years, 16 out of 192 cases were found to have extra-osseous primary tumors. RESULTS: Ages at initial diagnosis ranged from 2.5 to 17 years. Follow-up period ranged from 4 months to 24.8 years (mean 8.4 years). Eleven patients were treated according to protocols for Ewing tumors, while in 4 cases soft tissue protocols were used. In a single patient only surgery was done. Two patients had progressive disease despite chemotherapy; a third patient had only tumor response on the initial 2 chemotherapy courses. All 3 patients with initially metastatic disease died. One patient developed a second malignancy. Overall survival at 5 years was 75%. Event-free survival (EFS) at 5 years was 68%; for nonmetastatic patients 5-year EFS was 83%. CONCLUSION: The authors conclude that nonmetastasized extra-osseous Ewing tumors have a prognosis at least similar to that of osseous Ewing tumors.

Malignant mesothelioma after radiation treatment for Hodgkin lymphoma.

Malignant mesothelioma is a relatively uncommon malignancy. Although the pathogenesis is primarily related to asbestos, the disease may be associated with radiation exposure. Recently, increased risks for second primary mesothelioma after radiation for lymphoma have been reported. Because these findings are based on small numbers of patients, they need to be confirmed. We examined mesothelioma risk in 2567 5-year survivors of Hodgkin lymphoma. The risk was almost 30-fold increased in Hodgkin lymphoma patients treated with irradiation compared with the general population. Although histology and survival of the mesothelioma cases were comparable with cases from the general population, asbestos exposure and the proportion of males were lower than expected. The evidence for radiotherapy as cause for mesothelioma independent of exposure to asbestos is expanding, and the diagnosis of mesothelioma should be kept in mind whenever related symptoms arise in patients who had previous irradiation.

Results of diagnostic review in pediatric bone tumors and tumorlike lesions.

BACKGROUND: Histological examination of bone tumors is one of the most difficult subjects in pathology. In this manuscript, correctness of initial histological diagnosis in pediatric bone tumors and tumorlike lesions was investigated. PROCEDURE: All 262 bone tumor specimens of children up to the age of 19 years reviewed from 1999 to 2003 by the Netherlands Committee on Bone Tumors were included. Initial diagnosis and diagnosis after review were compared. RESULTS: Only 60% of original diagnoses proved to be correct. After classification according to the main categories of the World Health Organization classification, only 75% of tumors were correctly categorized. Thirteen of the 60 malignant tumors were not recognized as malignant. Seven of 198 benign lesions were reclassified as malignant. Kappa values were indicative for good agreement in the (by the Ministry of Health designated) bone tumor centers. For nondesignated hospital kappa values, a substantial lower level of agreement was noted. Agreement was almost perfect in Ewing/primitive neuroectodermal tumors. For cartilaginous, osteogenic, and fibrous tumors, agreement was lower. Adamantinomas were not recognized in non-bone tumor centers. For the remaining group composed of miscellaneous tumors, poor levels of agreement were noted. CONCLUSIONS: We conclude that correct diagnosis of childhood bone tumors requires review by a multidisciplinary team of experts. Specifically in non-bone tumor centers, the correctness of the initial diagnosis can be questioned.

Management of tumors of the chest wall in childhood: a review.

Chest wall tumors in childhood are major challenges with respect to diagnostic workup and treatment. Incidence rate is less than 1 per 1,000,000 and various benign and malignant diseases are noted. From the malignant diseases, Ewing tumors and rhabdomyosarcoma tumors are most often seen. Depending on diagnosis, staging, and age, therapy has to be tailored for each patient, which should be discussed in a multidisciplinary team setting. Radical resection is in most cases the major component of treatment. Use of chemotherapy depends on the diagnosis. In soft-tissue tumors, previously considered to be chemotherapy insensitive, favorable results are currently reported. The role of radiotherapy is debated owing to its pronounced late sequelae in children, but should be added when adequate margins cannot be achieved by surgery.

Incidence of biopsy-proven bone tumors in children: a report based on the Dutch pathology registration "PALGA".

INTRODUCTION: Data on childhood bone tumors are mainly confined to reports on malignant tumors or on institutional registries. Incidence figures on both benign and malignant bone tumors in childhood are lacking. METHODS: From January 1999 to December 2003, 1474 newly diagnosed bone tumors in children up to 18 years were registered in Pathologisch Anatomisch Landelijk Geautomatiseerd Archief (the nationwide network and registry of histopathology and cytopathology in The Netherlands). Data provided were diagnosis, date of birth, age at diagnosis, and localization. For incidence calculations, data on age and sex in each year of investigation were obtained from the StatLine database of Statistics Netherlands (www.cbs.nl). RESULTS/CONCLUSIONS: Incidence of pathology-proven bone tumors in children is low. Incidence of pathology-proven bone tumors in The Netherlands is 79.3 per 1,000,000. From the very first year of life, incidence increases from 3.9 per 1,000,000 to a peak at 13 to 15 years of 142.9 per 1,000,000. Osteochondromas are the most prevalent tumors, followed by aneurysmal bone cysts. The overall incidence is higher for male compared with female patients, mainly due to different frequencies found in aneurysmal bone cysts, Ewing sarcoma, and osteochondroma. Shifts in incidence differ among the various tumors. In infants, bone tumors are mainly chondromas and fibrous dysplasia, which both show a steady increase at older ages. Tumors most prevalent at older ages are osteochondromas, osteosarcomas, osteoid osteomas, and chondromas. A peak incidence at approximately the age of 10 is noted for solitary bone cysts, nonossifying fibromas, and osteoblastomas. Small children more often have localizations in the skull and facial bones. Comparison with literature data showed significant differences due to referral-based institutionally bias, whereas tumor registries only give data for specific tumor types.

Benzothiazole bipyridine complexes of ruthenium(II) with cytotoxic activity.

A series of benzothiazole-substituted trisbipyridine ruthenium(II) analogues {[Ru(bpy)(2)(4,5'-bbtb)](2+), [Ru(bpy)(2)(5,5'-bbtb)](2+) and [Ru(bpy)(2)(5-mbtb)](2+) [bpy is 2,2'-bipyridine, bbtb is bis(benzothiazol-2-yl)-2,2'-bipyridine, 5-mbtb is 5-(benzothiazol-2-yl),5'-methyl-2,2'-bipyridine]} have been prepared and compared with the complex [Ru(bpy)(2)(4,4'-bbtb)](2+) reported previously. From the UV-vis spectral studies, substitution at the 5-position of the bpy causes the ligand-centred transitions to occur at considerably lower energy than for those with the functionality at the 4-position, while at the same time causing the emission to be effectively quenched. However, substitution at the 4-position causes the metal-to-ligand charge transfer to occur at lower energies. Fluorescent intercalator displacement studies indicate that the doubly substituted complexes displace ethidium bromide from a range of oligonucleotides, with the greater preference shown for bulge and hairpin sequences by the Lambda enantiomer. Since the complexes only show small variation in the UV-vis spectra on the introduction of calf thymus DNA and a small increase in fluorescence they do not appear to be intercalators, but appear to associate within one of the grooves. All of the reported bisbenzothiazole complexes show reasonable cytotoxicity against a range of human cancer cell lines.

New mustard-linked 2-aryl-bis-benzimidazoles with anti-proliferative activity.

We describe new methodology for the synthesis of symmetric bis-benzimidazoles carrying 2-aryl moieties, including 2-[4-(3'-aminopropoxy)phenyl] and 2-[4-(3'-aminopropanamido)phenyl] substituents, together with the synthesis of novel hybrid molecules comprising bis-benzimidazoles in ester and amide combination with the N-mustard chlorambucil. The in vitro activities of these compounds against five cancer cell lines are also provided.

A new approach to combretastatin D2.

A concise and convergent route to combretastatin D2 is described together with some preliminary biological data.

Rasburicase (recombinant urate oxidase) for the management of hyperuricemia in patients with cancer: report of an international compassionate use study.

BACKGROUND: Hyperuricemia and tumor lysis syndrome (TLS) are serious complications that can occur during chemotherapy for hematologic malignancies, even if standard management procedures, including administration of allopurinol, are undertaken. Rasburicase, a recombinant urate oxidase that converts uric acid (UA) into the soluble compound allantoin, has been shown to control hyperuricemia faster and more reliably than allopurinol.(1) METHODS: A compassionate use trial, running from January 1999 to December 2001, provided access to rasburicase for patients in nine countries who were at risk for TLS during the initiation of chemotherapy. Of the 280 patients enrolled in the study, 278 received rasburicase and were included in the analysis. A total of 166 pediatric patients who had leukemia (approximately 74%), lymphoma (approximately 24%), or solid tumors (approximately 3%) were treated with rasburicase. One hundred twelve adults with either leukemia (68%) or lymphoma (30%) also were treated. Rasburicase (0.20 mg/kg) was administered intravenously once a day for 1 to 7 days, at the investigator's discretion. Two doses daily could be administered during the first 3 days. A response was defined as a reduction in UA level or maintenance of a UA level less than 7.5 mg/dL (or less than 6.5 mg/dL, for children age < 13 years). RESULTS: UA levels at 24-48 hours after administration of the last dose of rasburicase were available for 122 pediatric patients and 97 adult patients. The mean UA level in 29 hyperuricemic children decreased from 15.1 mg/dL to 0.4 mg/dL, whereas in 27 hyperuricemic adults, the mean level decreased from 14.2 mg/dL to 0.5 mg/dL. Prophylactic administration of rasburicase to prevent TLS during chemotherapy reduced UA levels from a mean of 4.4 mg/dL to 0.8 mg/dL in 93 nonhyperuricemic children and from 4.8 mg/dL to 0.4 mg/dL in 70 nonhyperuricemic adults (for all reductions in UA levels, P < 0.001). The response rate was 100%. Rasburicase was very well tolerated. Serious adverse events related to rasburicase were observed in one patient. CONCLUSIONS: The results of the current study confirm that rasburicase is safe and highly effective in the prevention and treatment of chemotherapy-induced hyperuricemia in both children and adults.