Signature of two-electron interference in angular resolved double photoionization of Mg.

The double photoionization of Mg has been studied experimentally and theoretically in a kinematic where the two photoelectrons equally share the excess energy. The observation of a symmetrized gerade amplitude, which strongly deviates from the Gaussian ansatz, is explained by a two-electron interference predicted theoretically, but never before observed experimentally. Similar to the Cooper minima in the single photoionization cross section, the effect finds its origin in the radial extent and oscillation of the target wave function.

Phase I study of gemcitabine (difluorodeoxycytidine) in children with relapsed or refractory leukemia (CCG-0955): a report from the Children's Cancer Group.

To determine the maximum tolerated dose (MTD) and assess the toxicity profile and pharmacokinetics of weekly gemcitabine infusions in pediatric patients with refractory hematologic malignancies. Fourteen patients under 21 years old were given infusions of gemcitabine for escalating durations at 10 mg/m2/min weekly for three consecutive weeks. Two males and two females were studied at each dose level. Pharmacokinetics of the drug's metabolism were measured by high pressure-liquid chromatography (HPLC) for 24 h after the first dose. Intracellular difluorodeoxycytidine triphosphate formation in leukemic blasts was measured in selected patients. The MTD of gemcitabine in these patients was 3600 mg/m2/week for three consecutive weeks (10 mg/m2/min for 360 min). Hepatotoxicity was the dose limiting toxicity. Thirty to fifty percent of patients exhibited fever, rash, or myalgia. Rare instances of hypotension and pulmonary toxicity were observed. Two of six patients [one acute lymphoblastic leukemia (ALL) and one acute myelogenous leukemia (AML)] treated at the MTD had at least M2 marrows, although peripheral blood counts did not recover sufficiently for the patients to be considered in complete response. Pharmacokinetics of gemcitabine fit a two-compartment open model with terminal half-life and plasma clearance value of 62 min and 2.2 l/min/m2, respectively. No gender differences were observed. In conclusion, the MTD of gemcitabine was 10 mg/m2/min for 360 min every week for 3 weeks. This is the recommended phase II dose schedule for children with leukemia. The activity of the drug at this schedule in heavily pretreated, refractory patients warrants a phase II trial in hematologic malignancies.

Phase I trial of autologous hematopoietic SCT with escalating doses of topotecan combined with CY and carboplatin in patients with relapsed or persistent ovarian or primary peritoneal carcinoma.

We designed a phase I clinical trial of escalating doses of topotecan with CY and carboplatin in combination with autologous hematopoietic SCT (AHSCT) for the treatment of relapsed or persistent platinum sensitive ovarian or primary peritoneal carcinoma. After stem cell collection, 16 patients received topotecan at 1.5, 2.5, 3.5, 4.5 or 6.0 mg/m(2)/d combined with CY 1.5 g/m(2)/d and carboplatin 200 mg/m(2)/d, all by 4-day continuous infusion. Steady state pharmacokinetics of topotecan and carboplatin were examined. Pre-treatment biopsies were examined for the expression of topoisomerase (topo) I, Ki67 and Bcl-2 family members by immunohistochemistry. One of six patients at a topotecan dose of 4.5 mg/m(2)/d and two of three patients at 6.0 mg/m(2)/d had dose-limiting toxicity of grade 3 stomatitis lasting >2 weeks. There was no treatment-related mortality. As topotecan clearance was constant over the dose range examined, topotecan steady state plasma concentrations increased with dose. Median progression-free survival and overall survival were 6.5 months and 2.7 years, respectively. Shorter progression-free survival was observed in tumors with low topo expression (P=0.04). Topotecan can safely be dose escalated to 4.5 mg/m(2)/d in combination with CY, carboplatin and AHSCT. This trial is registered at ClinicalTrials.gov as NCT00652691.

Validated high-performance liquid chromatographic assay for simultaneous determination of dacarbazine and the plasma metabolites 5-(3-hydroxymethyl-3-methyl-1-triazeno)imidazole-4-carboxamide and 5-(3-methyl-1-triazeno)imidazole-4-carboxamide.

Dacarbazine (DTIC) is a prodrug that is clinically effective in the treatment of Hodgkin's disease, melanoma and soft tissue sarcoma. To better characterize the clinical pharmacology of parent drug and reactive metabolites, a reversed-phase HPLC method with UV detection was developed for simultaneous determination of dacarbazine and the metabolites 5-(3-hydroxymethyl-3-methyl-1-triazeno)imidazole-4-carboxamide (HMMTIC) and 5-(3-methyl-1-triazeno)imidazole-4-carboxamide (MTIC). Chromatographic separation was achieved with a Zorbax SB-CN column and with a mobile phase of 80% 50 mM ammonium phosphate, pH 6.5, 20% methanol and 0.1% triethylamine. HMMTIC, MTIC and DTIC were extracted from plasma with methanol precipitation of the proteins. Recovery of DTIC and the metabolites from whole blood was greater than 92%. Rapid processing of whole blood, methanol extraction and storage at -70 degrees C substantially increased the stability of HMMTIC and MTIC from less than 15 min to 3 days. Precision for HMMTIC, MTIC and DTIC ranged from 3.7 to 16.3% relative standard deviation. The accuracy ranged from 101 to 114% for all three analytes. The validated assay was used to determine the pharmacokinetic data for dacarbazine and its active metabolites for human patients with recurrent glioma receiving DTIC intravenously.

A randomized phase II and pharmacokinetic study of dacarbazine in patients with recurrent glioma.

We conducted a randomized phase II study to determine the efficacy of dacarbazine (DTIC) in recurrent gliomas. Patients were randomly assigned to receive either DTIC 750 mg/m2 IV day 1 every 28 days (Arm A) or DTIC 200 mg/m2 IV days 1-5 every 28 days (Arm B). Pharmacokinetics were studied in 6 patients on each arm using HPLC analysis. Thirty-nine patients (30 male, 9 female), ages 27-67 years (median 53) were entered on the study (20 on Arm A, 19 on Arm B). No objective responses were seen. Median time to progression was 3 months. Median survival was 8 months. Treatment was generally well tolerated. Major toxicities were grade 1-2 nausea (33%). lethargy (28%), diarrhea (15%), alopecia (15%), and grade 3 neutropenia (8%). Four patients on Arm A had mild self-limited episodes of intravascular hemolysis occurring immediately after drug infusion, the mechanism of which is unknown. Mean AUC for DTIC, HMMTIC (5-[3-hydroxymethyl-3-methyl-1-triazeno] imidazole-4-carboxamide), and MTIC (5-[3-methyl-1-triazenol imidazole-4-carboxamide), in Arm A were 14.8, 0.17, and 1.15 mM min, respectively. Corresponding values for Arm B (on day 1 of 5) were 1.7, 0.06, and 0.29 mM min, respectively. The predicted HMMTIC and MTIC exposure over 5 days for Arm B, based on the day 1 data, is higher than with Arm A. We conclude that DTIC is well tolerated but does not have activity in patients with recurrent gliomas. The 5-day schedule appears less toxic, and pharmacokinetic studies show that it provides greater exposure to MTIC and HMMTIC compared to the one-day schedule.

Phase I trial of sequential administration of raltitrexed (Tomudex) and 5-iodo-2'-deoxyuridine (IdUrd).

Raltitrexed (Tomudex) is a specific inhibitor of thymidylate synthase with clinical activity in colorectal cancer. The combination of raltitrexed and 5-iodo-2'-deoxyuridine (IdUrd, a cytotoxic pyrimidine analog) resulted in increased IdUrd incorporation into DNA and exhibited in vitro synergism against colon and bladder human carcinoma cell lines. We designed a phase I trial to determine the MTD, pharmacokinetics, and biologic effects of escalating doses of the combination of IdUrd given as a 24-hour infusion after a raltitrexed 15-minute infusion every three weeks. Thirty-four patients received 95 courses of raltitrexed and IdUrd at doses ranging from raltitrexed 1 mg/m2 and IdUrd 750 mg/m2 to raltitrexed 2.5 mg/m2 and IdUrd 10,400 mg/m2. The median number of cycles administered was 2 (range 1-10). Dose limiting hematologic toxicity occurred at doses of raltitrexed 2.5 mg/m2 and IdUrd 10,400 mg/m2. In addition, we determined the mean plasma concentrations C(SS) of IdUrd, the iodouracil level at 22 hours and the IdUrd clearance. Raltitrexed did not appear to affect the pharmacokinetics of IdUrd in the dose range tested. The recommended phase II dose is raltitrexed 2 mg/m2 and IdUrd 10,400 mg/m2 repeated every three weeks. Evidence of potential antitumor activity was observed: 1 patient (with colon cancer) had a partial response while 15 others had stable disease.