Conduct of phase I trials in children with cancer.

PURPOSE AND METHODS: Future progress in the care of children with cancer requires appropriate evaluations of promising new agents for pediatric indications, beginning with well-conducted phase I trials. This report summarizes current guidelines for the conduct of pediatric phase I trials and represents a consensus between American and European investigators. The primary objective of pediatric phase I trials is to define safe and appropriate doses and schedules of new agents that can subsequently be used in phase II trials to test for activity against specific childhood malignancies. Prioritization of agents for evaluation in children is critical, since many more investigational agents are evaluated in adult patients than can be systematically evaluated in children. Considerations used in prioritizing agents include activity in xenograft models, novel mechanism of action, favorable drug-resistance profile, and activity observed in adult trials of the agent. RESULTS AND CONCLUSION: Distinctive characteristics of pediatric phase I trials, in comparison to adult phase I trials, include the necessity for multiinstitutional participation and their higher starting dose (typically 80% of the adult maximum-tolerated dose [MTD]), both of which reflect the relative unavailability of appropriate patients. The application of uniform eligibility criteria and standard definitions for MTD and dose-limiting toxicity (DLT) help to assure that pediatric phase I trials are safely conducted and reliably identify appropriate doses and schedules of agents for phase II evaluation. Where possible, pediatric phase I trials also define the pharmacokinetic behavior of new agents in children.

Determination of intracellular levels of 6-mercaptopurine metabolites in erythrocytes utilizing capillary electrophoresis with laser-induced fluorescence detection.

Capillary electrophoresis proved to be a useful technique for the analysis of intracellular levels of 6-thioguanosine mono-, di-, and triphosphate with analysis times of 20 min. Conditions required for baseline separation of the thioguanine nucleotides consisted of a 25 mM KH2PO4 (pH 8.0) buffer and a separation voltage of +28 kV. Laser-induced fluorescence detection (lambda ex = 325 nm, lambda em = 410 nm) of the thioguanine nucleotide metabolites of 6-mercaptopurine (6-MP) was possible following oxidation of the thiol functionality. Tedious extraction procedures involving mercury cellulose resins or phenyl mercury adduct formation, which had been required previously for the selective extraction of thiopurines from erythrocytes, were unnecessary due to the overall specificity of the approach. However, the inclusion of 50 mM EDTA in the sample preparation was required to inhibit the anabolic/catabolic enzymatic activity, which was responsible for the degradation of the analytes. The method demonstrated linearity from 5 to 1700 pmol/100 microliters red blood cells for the three analytes (RSDs < or = 8%). The feasibility of the method was demonstrated for the quantitation of 6-thioguanine nucleotides in patients receiving either oral or intravenous 6-MP therapy.

Reversal of 6-mercaptopurine and 6-methylmercaptopurine ribonucleoside cytotoxicity by amidoimidazole carboxamide ribonucleoside in Molt F4 human malignant T-lymphoblasts.

Cytotoxicity of 6-mercaptopurine (6MP) and 6-methylmercaptopurine ribonucleoside (Me-MPR) was studied in Molt F4 human malignant lymphoblasts. Both drugs are converted into methylthioIMP (Me-tIMP), which inhibits purine de novo synthesis. Addition of amidoimidazole carboxamide ribonucleoside (AICAR) circumvented inhibition of purine de novo synthesis, and thus partly prevented 6MP and Me-MPR cytotoxicity. Purine nucleotides, and especially adenine nucleotides, were recovered by addition of AICAR. Under these conditions, Me-tIMP formation decreased. The results of this study indicate that formation of Me-tIMP may be important for 6MP cytotoxicity in Molt F4 cells. These data suggest that depletion of adenine nucleotides is the main cause for Me-tIMP cytotoxicity.

Ploidy of lymphoblasts is the strongest predictor of treatment outcome in B-progenitor cell acute lymphoblastic leukemia of childhood: a Pediatric Oncology Group study.

PURPOSE: Using the technique of recursive partitioning and amalgamation analysis with verification, the Pediatric Oncology Group (POG) investigated the independent prognostic significance of previously published prognostic factors significantly associated with event-free survival (EFS) in B-progenitor cell acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Age, leukocyte count, sex, immunophenotype (expression of cytoplasmic immunoglobulin [Ig] and of surface antigens CD10 and CD34), and DNA index (ratio of the flow cytometry-determined DNA content of leukemia cells to that of normal diploid cells) were the variables used in the evaluation of four antimetabolite-based chemotherapy regimens in 1,535 children with the newly diagnosed B-progenitor cell ALL between February 1986 and May 1990. RESULTS: There were three subgroups at widely different risks of treatment failure. A DNA index greater than 1.16 was the most prognostic feature. The final prognostic subgrouping was as follows: (1) DNA index greater than 1.16; (2) DNA index less than or equal to 1.16, age less than 11.0 years, and leukocyte count less than 50 x 10(9)/L; and (3) DNA index less than or equal to 1.16, (age greater than 11.0 years, and/or leukocyte count greater than 50 x 10(9)/L). These groups made up 20%, 53%, and 27% of the patients and had 4-year EFS rates (SE) of 90.1% (6.3%), 80.5% (5.1%), and 50.4% (7.6%), respectively. CONCLUSIONS: Use of the DNA index, leukocyte count, and age--data that are relatively inexpensive and simple to obtain--may be sufficient to stratify patients with B-progenitor cell ALL for risk-directed therapy. Patients at an extremely low risk of failing therapy (approximately 20% of cases in this study) can thus be identified and spared the toxic short-term and late effects of more intensive therapies that may be needed for children with less favorable clinical and biologic features.

Metastasizing chordoma in early childhood: a pathological and immunohistochemical study with review of the literature.

A 2 1/2-year-old female with a sphenooccipital-vertebral chordoma presented with neck pain, torticollis, fever, a lytic lesion of C2 vertebra, and bilateral nodular infiltrates in the lung. The lung biopsy revealed multiple tumor emboli by an enigmatic epithelioid-appearing neoplasm with immunohistochemical staining for vimentin, cytokeratin, and epithelial membrane antigen. A thorough roentgenographic evaluation disclosed a destructive, prepontine mass in the region of the clivus, erosion of the odontoid process, and compression of the cervical spinal cord. The patient died after a clinical course of 3 months. We identified 16 additional cases of metastasizing chordomas in the pediatric-age population; this case is the first to our knowledge with pathologically documented pulmonary metastasis at presentation.

Prolonged echoviral meningitis in a cancer patient with normal serum immunoglobulins.

This is a report of prolonged meningitis caused by echovirus type 20 in a patient with rhabdomyosarcoma. It represents one of the few documented cases of delayed clearance of echovirus in the cerebrospinal fluid in a patient with normal serum immunoglobulins. The case illustrates the prolonged clinical course of echoviral meningitis in a patient receiving cytotoxic drug therapy, and it suggests that factor(s) other than humoral antibodies may be involved in the elimination of echovirus from the central nervous system.

Pediatric Oncology Group experience with modified LSA2-L2 therapy in 107 children with non-Hodgkin's lymphoma (Burkitt's lymphoma excluded).

From September 1976 to August 1979 the Pediatric Oncology Group accessed 145 children to study the effectiveness of modified LSA2-L2 therapy for the treatment of non-Hodgkin's lymphoma (NHL). Burkitt's lymphoma patients were ineligible; E-rosette-positive patients with greater than or equal to 25% blasts in the marrow entered after February 1977 were reported separately. Radiotherapy could be used to treat patients with compressive mediastinal disease at diagnosis and was prescribed for those with residual abdominal disease as demonstrated by second-look surgery on completion of induction chemotherapy. Confirmation of diagnosis by the Pathology Panel and Repository Center for Lymphoma Clinical Trials was mandatory. Diagnostic tissues of 131 patients were reviewed. Among 107 evaluable patients, 91 (85%) achieved complete remission. Differences in response rates among the three major histologic groups (lymphoblastic, undifferentiated, and large cell) were of statistical significance, with response being poorest for diffuse undifferentiated lymphoma (P = 0.03). Failure-free survival did not differ significantly for the three major histologic diagnoses. While response rate was lowest for Murphy Stage III patients (79%), the differences among the stages were not significant. Stage was not a significant prognostic factor for failure-free survival (P = 0.08). The number of patients still at risk and the Kaplan-Meier estimate of percentage of patients remaining at risk after 3 years is: Stage I, 8 (100%); Stage II, 10 (67%); Stage III, 28 (57%); Stage IV, 6 (39%); and greater than 25% blasts, 1 (13%). Stage III failure curves for lymphoblastic disease show continuing stepwise failure through 3 years. Among patients with diffuse large cell and undifferentiated disease, most failures occurred by 8 months. M1 and M2 levels of marrow involvement were not prognostic among children with lymphoblastic disease. The presence of a mediastinal mass was a significant factor contributing to failure in children with lymphoblastic disease without marrow involvement. Leucocytosis greater than 10,000/1, was a significant (P = less than 0.001) factor predicting failure-free survival for patients with large cell lymphoma. The delivery of radiotherapy was not a significant factor in achieving remission. No consistent benefit resulted from using radiotherapy to treat postinduction residual disease demonstrated on second-look exploration. The LSA2-L2 regimen was associated with considerable toxicity, severe or worse in 77% and life-threatening to 40% of these patients. Four died of toxicity. However, therapy was given more easily and safely as investigator experience increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Management of children with isolated testicular leukemia.

Since 1975, nine children with testicular leukemia were treated at the University of Kansas Medical Center on a standard protocol. Six patients presented with overt testicular leukemia and three patients had microscopic testicular leukemia detected on a biopsy done after 3 years of continuous complete remission. All patients had an M1 bone marrow at the time of testicular relapse and one patient had a concomitant central nervous system (CNS) relapse. Therapy consisted of testicular irradiation, CNS chemoprophylaxis, and systemic reinduction chemotherapy. Systemic maintenance therapy after the testicular relapse consisted of 6-mercaptopurine and methotrexate with vincristine/prednisone pulses administered in the same basic dose and schedule as the patient's original maintenance regimen. These nine patients had a mean duration of first remission of 33 months and a mean duration of second remission of 45+ months. Four patients have relapsed (two bone marrow, one CNS, one CNS + bone marrow), but five patients remain in their second complete remission for 33+ to 94+ months from the time of testicular relapse. These results demonstrate that, in some children, testicular leukemia represents a site of temporary drug resistance and long-term second remissions can be obtained (once local disease is controlled) by using the initial maintenance chemotherapy regimen.

Utilization of a human tumor cloning system to monitor for bone marrow involvement in children with non-hodgkin's lymphoma.

The objective of this study was to evaluate the sensitivity of two methods for determining bone marrow involvement with non-Hodgkin's lymphoma. These methods were histologic review of bone marrow aspirates, and clot sections versus in vitro growth of lymphoma colonies on soft agar. Forty-two bone marrow aspirates were studied from 14 children who were without bone marrow involvement at diagnosis. There were seven bone marrow aspirates (from five patients) that had histologic evidence of metastatic lymphoma. Six of these seven specimens formed colonies in vitro. Twenty-nine of 35 histologically negative specimens showed no lymphoma colony growth. However, six histologically negative specimens (from three patients) formed lymphoma colonies. Both the Fisher's exact test and the K statistic were significant, indicating not only an association between histology and in vitro culture results, but also a close agreement. In addition, growth of lymphoma colonies in vitro was associated statistically with both a short duration of complete remission and a short duration of survival.

In vitro sensitivity of normal granulocytic and lymphoma colonies to vinca alkaloids.

Recently, a colony-forming assay was developed in our laboratory for pediatric malignant lymphoid diseases. This assay supports the growth of lymphoma colonies (ML-CFC) as well as normal granulocytic colonies (CFU-C) and thus a direct comparison between the antineoplastic and myelosuppressive effects of a drug can be determined. To test specificity of this in vitro assay to structurally similar drugs, the inhibitory effects of three vinca alkaloids (vincristine, vindesine, vinblastine) on ML-CFC (B-, T-, pre-T-cell types) and CFU-C was determined. Our results demonstrate that all three vinca alkaloids were active agents in vitro and that a direct dose response effect occurred once a threshold dose was reached. Each vinca alkaloid had a different pattern of inhibitory effect on ML-CFC and CFU-C suggesting an inherent difference in drug metabolism by these cells. Also, based on the dose inhibiting 50% of colony formation, vinblastine was 94 times more inhibitory against malignant B-cell ML-CFCs than against granulocytic CFU-C.

Vindesine and prednisone for remission induction in children with acute lymphocytic leukemia.

Vinca alkaloids are effective anticancer agents. Vindesine is a recent vinca alkaloid derivative with anti-tumor effects shown in in vitro systems and in patients with acute lymphocytic leukemia (ALL). The present study was designed to investigate the therapeutic effectiveness and toxicity of vindesine in combination with prednisone for remission induction in late stage ALL in children. Sixteen children with late-stage ALL were treated with vindesine 4.0 mg/m2/week intravenously and prednisone 60 mg/m2/day orally in four divided doses for minimum of three weeks. Thirteen children were evaluable. Of these patients, four had complete remission and four had partial response. Toxicity was well tolerated and consisted of bone pain, paresthesias, loss of deep tendon reflexes, leukopenia, and thrombocytopenia primarily. Abnormal liver function tests and fever were also noted in some patients. All patients had received vincristine and prednisone prior to vindesine prednisone combination. All patients had been resistant to vincristine prednisone combination prior to vindesine prednisone treatment. This study suggests effectiveness of vindesine in late stage ALL and lack of cross-resistance of vindesine and vincristine.