Saturable pharmacokinetics and paclitaxel pharmacodynamics in children with solid tumors.

PURPOSE: Our aim was to evaluate the pharmacokinetics and pharmacodynamics of paclitaxel (Taxol; Bristol-Myers Squibb Co, Princeton, NJ) in children, and to determine whether paclitaxel exhibited saturable pharmacokinetics. PATIENTS AND METHODS: We evaluated the pharmacokinetics and pharmacodynamics of paclitaxel (200 to 420 mg/m2) administered as a 24-hour intravenous (i.v.) infusion in a phase 1 study of 30 pediatric patients (age, 2.3 to 22.8 years) with refractory solid tumors. Fourteen serial blood samples were obtained during and up to 48 hours after the infusion, and paclitaxel concentrations were measured by a high-performance liquid chromatography-UV (HPLC-UV) method. Four pharmacokinetic models were compared for their ability to describe the patients' data. RESULTS: Paclitaxel disposition was not consistent with a first-order, two-compartment pharmacokinetic model. Rather, the majority of data sets were best described by a two-compartment model that incorporated both saturable tissue distribution and saturable elimination; a smaller number of patient data sets were best described by models that incorporated either saturable distribution or saturable elimination. Clearance was dose-dependent, with a median clearance at the lower dosages (< 400 mg/m2) of 161 mL/min/m2, and at the highest dosages (> 400 mg/m2) of 123 mL/min/m2 (P = .044). The duration that paclitaxel plasma concentrations exceeded 0.1 mumol/L was highly variable (range, 26 to 71 hours). There was a trend toward higher median area under the concentration-versus-time curve (AUC) in those children with musculoskeletal (72 mumol/L.h; P = .054) or neurologic toxicity (54 mumol/L.h; P = .062) versus those without toxicity (30 mumol/L.h). Toxicity was not significantly correlated with dosage. CONCLUSION: We conclude that paclitaxel distribution and elimination are saturable, and that estimates of paclitaxel systemic exposure correlate better with toxicity than does dosage.

Phase I trial of paclitaxel in children with refractory solid tumors: a Pediatric Oncology Group Study.

PURPOSE: A phase I study was performed to describe the principal toxicities and identify the maximum-tolerated dose (MTD) of Taxol (paclitaxel; Bristol-Myers Squibb Co, Wallingford, CT) in children with therapy-resistant solid tumors. Additionally, the pharmacokinetic disposition of Taxol in children was studied, and preliminary evidence of the activity of Taxol against pediatric solid tumors was assessed. PATIENTS AND METHODS: Twenty-four-hour continuous infusions of Taxol were administered every 21 days to children (median age, 12 years; range, 2 to 22) with refractory solid tumors. Doses ranged from 200 to 420 mg/m2, there was no intrapatient dose escalation. RESULTS: A total of 62 courses of Taxol were administered to 31 patients. Two patients developed acute anaphylaxis during their second infusion of taxol at doses of 200 mg/m2 and 350 mg/m2, respectively. No other allergic reactions were documented. Myelosuppression occurred at all dose levels, but was of short duration (< or = 7 days) and did not appear to increase with consecutive courses or at higher dosage levels. A stocking-and-glove peripheral neuropathy became evident at doses > or = 290 mg/m2. Dose-limiting neurotoxicity occurred at 420 mg/m2 and comprised a significant fine-motor and peripheral neuropathy in one patient, and a tonic-clonic seizure in another. End-of-infusion plasma concentrations ranged from 0.40 to 6.4 mumol/L, and were not found to be dose-dependent over the range of doses studied. A complete response was documented in one patient, partial response in two, and minimal response in one for an overall response rate of 13%. CONCLUSION: Neurotoxicity was dose-limiting when Taxol was administered by 24-hour continuous infusion to pediatric patients with relapsed solid tumors. In this population, the recommended dose for phase II trials is 350 mg/m2/d.

Invasive fungal disease in pediatric acute leukemia patients with fever and neutropenia during induction chemotherapy: a multivariate analysis of risk factors.

We evaluated the courses of 115 consecutive cases of pediatric acute leukemia treated with induction chemotherapy. Seventy-two patients developed fever associated with neutropenia; 15 developed systemic fungal infections. We reviewed multiple demographic and treatment characteristics of these patients in an attempt to identify potential risk factors for the development of invasive fungal disease (IFD). Risk factors identified in a univariate analysis included duration of neutropenia after first fever (P less than .0001), diagnosis of acute nonlymphocytic leukemia (ANLL) (P = .003), onset of fever and neutropenia within 5 days of starting induction chemotherapy (P = .009), and multiple (greater than one) surveillance culture sites positive for fungal organisms (P = .02). In a multiple logistic regression analysis, duration of neutropenia (P less than .001) remained a significant risk factor. The study group of patients had a significantly higher risk of fungal infections than a matched group of leukemia patients developing fever with neutropenia due to postremission consolidation chemotherapy (P = .003). In the first 48 patients, 14 (29%) developed IFD. In the subsequent patients (n = 24), intravenous miconazole (5 mg/kg every 8 hours) was begun at the time of the first fever. One of the 24 patients (4%) given miconazole developed IFD. The use of miconazole was a negative risk factor for the development of IFD in univariate (P = .01) and multivariate (P = .05) analysis. We conclude that pediatric leukemia patients who develop fever associated with neutropenia during induction chemotherapy are at high risk for developing IFD. The role of intravenous miconazole at the time of the first fever in this group deserves further study.

Secondary acute myeloid leukemia in children previously treated with alkylating agents, intercalating topoisomerase II inhibitors, and irradiation.

PURPOSE: Patient records were reviewed to identify cases of secondary acute myeloid leukemia (AML) with clinical and cytogenetic features characteristic of classic epipodophyllotoxin-related AML in patients whose prior treatment for cancer did not include these agents. PATIENTS AND METHODS: Four cases of secondary AML with chromosomal abnormalities involving bands 11q23 and 21q22, in the absence of prior treatment with etoposide or teniposide, were identified among patients treated at St Jude Children's Research Hospital between January 1980 and April 1992. RESULTS: The four identified patients were initially treated for rhabdomyosarcoma, non-Hodgkin's lymphoma (n = 2), and Hodgkins' disease. Prior chemotherapy included relatively low cumulative doses of doxorubicin (median, 150 mg/m2; range, 120 to 375 mg/m2) and cyclophosphamide (median, 3,100 mg/m2; range, 2,250 to 11,400 mg/m2). All four patients had received radiation therapy: 59.4 Gy to the right middle ear for rhabdomyosarcoma; 15 Gy and 12 Gy to the abdomen and right lower quadrant, respectively, for non-Hodgkin's lymphoma; 27 Gy to the right orbit for non-Hodgkin's lymphoma; and 36.6 Gy to the mantle-paraaortic-spleen regions plus 20.4 Gy inverted-Y radiation at relapse for Hodgkin's disease. Secondary AML was diagnosed a median of 38 months after initial diagnosis (range, 14 to 55). Leukemic cell translocations involved band 11q23 in two cases and band 21q22 in two. Although all patients obtained a complete remission (CR), only one remains disease-free (at 34 months), following an allogeneic bone marrow transplant. CONCLUSION: Intercalating topoisomerase II inhibitors (doxorubicin, dactinomycin), when combined with alkylating agents and irradiation, may cause secondary AML.

Treatment of recurrent and refractory pediatric solid tumors with high-dose busulfan and cyclophosphamide followed by autologous bone marrow rescue.

PURPOSE: The purpose of this study was to determine the toxicities of and responses to high-dose busulfan and cyclophosphamide with autologous bone marrow transplant (ABMT) in patients with recurrent or refractory pediatric solid tumors. PATIENTS AND METHODS: We treated 18 patients (ages, 2 to 38 years; median, 14) who had tumors that were resistant to conventional chemotherapy and radiotherapy with busulfan 16 mg/kg and cyclophosphamide 200 mg/kg. Seventeen patients received bone marrow purged with 4-hydroperoxycyclophosphamide; one received unpurged marrow. RESULTS: Despite extensive prior treatment, including radiotherapy in 16 patients, toxicity generally was acceptable. For seven patients with measurable disease, there were three partial responses of 2, 10, and 20 months' duration, three patients with stable disease (SD), and one early, toxic death. Of the 11 patients with no measurable disease at the time of transplantation, one patient with osteosarcoma continues in remission at 57+ months and one third of the patients survived for at least 16 months. Mucositis was the predominant nonhematopoietic toxicity. CONCLUSION: Although the high-dose busulfan and cyclophosphamide combination showed modest activity, changes in the preparative regimen should be considered to improve the response rate in refractory tumors.

Experience with 2-chlorodeoxyadenosine in previously untreated children with newly diagnosed acute myeloid leukemia and myelodysplastic diseases.

PURPOSE: To develop more effective chemotherapy regimens for childhood acute myelogenous leukemia (AML). PATIENTS AND METHODS: Between June 1991 and December 1996, we administered the nucleoside analog 2-chlorodeoxyadenosine (2-CDA) to 73 children with primary AML and 20 children with secondary AML or myelodysplastic syndrome (MDS). Patients received one or two 5-day courses of 2-CDA (8.9 mg/m(2)/d) given by continuous infusion. All patients then received one to three courses of daunomycin, cytarabine, and etoposide (DAV) remission induction therapy. RESULTS: Seventy-two patients with primary AML were assessable for response. Their rate of complete remission (CR) was 24% after one course of 2-CDA, 40% after two courses of 2-CDA, and 78% after DAV therapy. Of the 57 patients who entered CR, 11 subsequently underwent allogeneic bone marrow transplantation (BMT), and 40 underwent autologous BMT. Twenty-nine patients remain in continuous CR after BMT. Two patients remain in CR after chemotherapy only. The 5-year event-free survival (EFS) estimate was 40% (SE = 0.080%). Patients with French-American-British (FAB) M5 AML had a higher rate of CR after treatment with 2-CDA (45% after one course and 70.6% after two courses) than did others (P =.002). In contrast, no patient with FAB M7 AML (n = 10) entered CR after treatment with 2-CDA. Similarly, no patient with primary MDS (n = 6) responded to 2-CDA. Seven patients with secondary AML or MDS (n = 14) had a partial response to one course of 2-CDA. CONCLUSION: This agent was well tolerated, and its toxicity was acceptable. Future trials should examine the effectiveness of 2-CDA given in combination with other agents effective against AML.

N-CAM (CD56) expression by CD34+ malignant myeloblasts has implications for minimal residual disease detection in acute myeloid leukemia.

The molecules detected by CD34 and CD56 monoclonal antibodies are simultaneously expressed in approximately 20% of childhood acute myeloid leukemia (AML) cases, and this phenotype is associated with t(8;21)(q22;q22) karyotype. By contrast, bone marrow samples from normal donors (n = 5) and patients with CD56- malignancies in remission (n = 8) contained fewer than 1 in 10,000 CD34+/CD56+ cells. CD34+/CD56+ cells were readily identified when leukemic blasts were admixed with normal bone marrow cells at a 1:10(4) ratio. Cells expressing both markers (0.01-0.8% of mononuclear cells) were also found in bone marrow samples from two of three children with CD34+/CD56+ AML studied, who were in remission by morphologic criteria. In one of these patients, detection of residual disease by flow cytometry anticipated overt hematologic relapse. A second patient, in whom minimal residual disease was detected prior to and following autografting, died of unrelated causes while in morphologic remission. The third patient had no detectable residual disease prior to and following autografting, and is still in morphologic and immunologic remission 100+ days post-transplant. The expression of CD56 on CD34+ cells is leukemia-associated and offers a means of identifying extremely small numbers of these cells by flow cytometry. This sensitive approach can now be used to assess the efficacy of treatment and detect early relapse in patients with CD34+/CD56+ AML.

Flow cytometric detection of rare normal human marrow cells with immunophenotypes characteristic of acute lymphoblastic leukemia cells.

Rare subpopulations of normal marrow B lymphoid cells expressing immunophenotypes typically found in B-lineage acute lymphoblastic leukaemias (ALL) were sought by multiparameter flow cytometry. First, CD34+ marrow leukocytes were isolated by immune adherence using immunomagnetic microspheres, and analyzed for coexpression of the following pairs of membrane antigens: CD34 CD22; CD34 CD20; and CD10 CD22. Terminal deoxynucleotidyl transferase expression was not assessed. All three antigen combinations were found on small percentages of the CD34-enriched cell population. Second, unseparated normal low density marrow leukocytes were examined by 'gating' on cells with the right-angle light scatter of lymphoid cells, plus either CD34+ or CD10+ immunofluorescence. This independent approach confirmed that rare subsets of normal cells coexpress 'immature' and 'mature' differentiation antigens. In addition, remission marrow cells were examined from two children who had completed therapy for ALL two and four months earlier. Both specimens had a more than threefold increase in CD34+ cells over normal marrow, and cells coexpressing immature and mature cell surface antigens were easily detected. These findings demonstrate that immunophenotypes characteristic of B-lineage ALL, previously labeled 'asynchronous' with respect to the developmental sequence of the majority of normal B lymphoid cells, exist at low frequency in normal human bone marrow.

Current strategies for treatment of acute myeloid leukemia at St Jude Children's Research Hospital.

We examined the feasibility of maintaining specific plasma concentrations of ara-C and VP-16 in children with AML. Sixty-one children were treated with 6 sequential cycles of intensive chemotherapy consisting of: (1) cytarabine (ara-C)/VP-16, (2) ara-C/daunorubicin (Dauno), (3) VP-16/amsacrine (m-AMSA), (4) VP-16/5-azacytidine (5-Az), (5) ara-C/Dauno, and (6) ara-C/VP-16. Fifty-nine children had de novo AML, and 2 had a previous myelodysplastic syndrome. The number of patients with each specific FAB subtype was: M0-1; M1-7; M2-24; M3-7; M4-5; M5-11; and M7-6. Simultaneous continuous infusions of ara-C and VP-16 (cycle 1) given at individualized doses to achieve drug plasma concentrations of 1 microM and 30 microM, respectively, produced complete remission (CR) in 26 of 61 patients (43%); an additional 17 patients entered CR after Dauno/ara-C (cycle 2), and one patient required 4 cycles of chemotherapy to achieve CR (total CR rate = 72%). The preliminary 2-year event-free survival (EFS) for patients with FAB-M1 and -M2 AML was only 15% versus 40% for those with FAB-M4 and -M5 AML. Overall, 21 of the 61 patients remain in CR (2-yr EFS = 29%). We conclude that intense treatment with ara-C and VP-16 at doses individualized to achieve target plasma concentrations is feasible although severely myelosuppressive. It results in an acceptable CR rate, but does not improve EFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of recombinant human hematopoietic growth factors on leukemic blasts from children with acute myeloblastic or lymphoblastic leukemia.

The responses of blast cells from 52 cases of pediatric acute myeloid leukemia (AML) and 81 cases of acute lymphocytic leukemia (ALL) to 11 hematopoietic growth factors were determined using a 3H-thymidine assay. There was considerable variation in the ability of growth factors to stimulate thymidine incorporation among individual cases of AML. Blasts from almost one half of the patients (25 out of 52) with AML were responsive to growth factors such as IL-3, G-CSF, or GM-CSF. Alternatively, 37% of AML cases (19 out of 52) showed little (< 2.5 times background) thymidine incorporation in the presence of growth factors; such cases were classified as nonresponsive. All AML cases expressing mixed-lineage characteristics (expression of lymphoid-associated antigens) were non-responsive. In 15% of the cases (9 out of 52), blasts incorporated high levels of thymidine without growth factors and there was no increase in 3H-thymidine incorporation in the presence of growth factors. Such cases were classified as independent. The response to growth factors did not correlate with other biological characteristics such as the FAB morphologic classification or specific chromosomal abnormalities. In striking contrast to AML cases, blast sells from only a few of the ALL cases studied showed any response to growth factors. These results demonstrate that growth factor responsiveness is a unique biological characteristic of the leukemic blasts and does not appear to correlate with other easily identified biological features.

Clinical significance of CD10 expression in childhood acute lymphoblastic leukemia.

The independent significance of CD10 expression in childhood acute lymphoblastic leukemia (ALL) is uncertain because most studies have not adjusted for other risk features, such as age and immunophenotype, or for treatment effects. We reassessed the clinical importance of CD10 expression in patients who received highly effective contemporary treatment. CD10 antigen was detected in blast cells from 384 of 408 patients (94%) with B-lineage ALL and 36 of 90 (40%) with T-cell ALL. In the B-lineage subgroup, CD10 expression was associated with favorable presenting features: age > or = 1 year, lower leukocyte count (< 50 x 10(9)/l), and leukemic cell DNA index > or = 1.16 or hyperdiploidy > 50 chromosomes. One-half of the patients with CD10- B-lineage ALL had 11q23 chromosomal abnormalities. Separate analysis of the marker in T-cell ALL revealed no differences between CD10+ and CD10- cases in clinical features or karyotypic patterns, with the exception of a lower frequency of central nervous system leukemia and a higher frequency of 9p abnormalities in the former subgroup. CD10+ T-cell cases were also significantly more likely than CD10- cases to coexpress CD21, CD1, CD4, or CD8. Lack of CD10 expression was independently associated with an adverse prognosis in T-cell ALL (p = 0.02). However, for the larger subgroup of patients with B-lineage ALL, CD10 expression has no independent prognostic significance.

Results of Dana-Farber Cancer Institute Consortium protocols for children with newly diagnosed acute lymphoblastic leukemia (1981-1995).

The Dana-Farber Cancer Institute (DFCI) ALL consortium has been conducting clinical trials in childhood acute lymphoblastic leukemia (ALL) since 1981. The treatment backbone has included intensive, multi-agent remission induction, early intensification with weekly, high-dose asparaginase, cranial radiation for the majority of patients, frequent vincristine/ corticosteroid pulses during post-remission therapy, and for high-risk patients, doxorubicin during intensification. Between 1981 and 1995, 1,255 children with newly diagnosed ALL were evaluated on four consecutive protocols: 81-01 (1981-1985), 85-01 (1985-1987), 87-01 (1987-1991) and 91-01 (1991-1995). The 5-year event-free survival (EFS) rates (+/- standard error) for all patients by protocol were as follows: 74 +/- 3% (81-01), 78 +/- 3% (85-01), 77 +/- 2% (87-01) and 83 +/- 2% (91-01). The 5-year EFS rates ranged from 78 to 85% for patients with B-progenitor phenotype retrospectively classified as NCI standard-risk, 63-82% for NCI high-risk B-progenitor patients, and 70-79% for patients with T cell phenotype. Results of randomized studies revealed that neither high-dose methotrexate during induction (protocol 87-01) nor high-dose 6-mercaptopurine during intensification (protocol 91-01) were associated with improvement in EFS compared with standard doses. Current studies continue to focus on improving efficacy while minimizing acute and late toxicities.

A Phase I trial of bryostatin-1 in children with refractory solid tumors: a Pediatric Oncology Group study.

Bryostatin-1, a macrocyclic lactone, appears to elicit a wide range of biological responses including modulation of protein kinase C (PKC). PKC, one of the major elements in the signal transduction pathway, is involved in the regulation of cell growth, differentiation, gene expression, and tumor promotion. Because of the potential for a unique mechanism of interaction with tumorgenesis, a Phase I trial of bryostatin-1 was performed in children with solid tumors to: (a) establish the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD); (b) establish the pharmacokinetic profile in children; and (c) document any evidence of antitumor activity. A 1-h infusion of bryostatin-1 in a PET formulation (60% polyethylene glycol 400, 30% ethanol, and 10% Tween 80) was administered weekly for 3 weeks to 22 children (age range, 2-21 years) with malignant solid tumors refractory to conventional therapy. Doses ranged from 20 to 57 microg/m2/ dose. Pharmacokinetics were performed in at least three patients per dose level. The first course was used to determine the DLT and MTD. Twenty-two patients on five dose levels were evaluable for toxicities. At the 57 microg/m2/dose level dose-limiting myalgia (grade 3) was observed in three patients; two of those patients also experienced photophobia or eye pain, and one experienced headache. Symptoms occurred in all patients within 24-72 h after the second dose of bryostatin-1 with resolution within 1 week of onset. Other observed toxicities (grades 1 and 2) included elevation in liver transaminases, thrombocytopenia, fever, and flu-like symptoms. The bryostatin-1 infusion was typically well tolerated. Although stable disease was noted in several patients, no complete or partial responses were observed. The recommended Phase II dose of bryostatin-1 administered as a 1-h infusion weekly for 3 of every 4 weeks to children with solid tumors is 44 microg/m2/dose. Myalgia, photophobia, or eye pain, as well as headache, were found to be dose limiting.

Diffuse alveolar hemorrhage associated with Mycoplasma hominis respiratory tract infection in a bone marrow transplant recipient.

An 18-year-old woman developed respiratory distress and diffuse pulmonary infiltrates after allogeneic bone marrow transplantation. Bronchoalveolar lavage findings indicated diffuse alveolar hemorrhage. Cultures of the lavage fluid and the pharynx grew Mycoplasma species; the pharyngeal isolate was identified as Mycoplasma hominis. Mycoplasma hominis infection may have an etiologic role in diffuse alveolar hemorrhage.

XomaZyme-CD5 immunotoxin in conjunction with partial T cell depletion for prevention of graft rejection and graft-versus-host disease after bone marrow transplantation from matched unrelated donors.

Patients who receive bone marrow transplants from unrelated donors have a high incidence of graft-versus-host disease (GVHD). If the donor marrow is first T cell-depleted, the everity of GVHD declines but the risk of rejection rises. In an attempt to prevent both graft rejection and GVHD, we included an anti-T cell antibody-toxin conjugate (CD-5-Ricin; XomaZyme H65) in the transplant conditioning regimen. After receiving a partially T cell-depleted marrow, patients then received a second course of immunotoxin as additional GVHD prophylaxis. Eight recipients of unrelated donor marrow transplants were studied. All engrafted (ANC > 500 x 10(6)/l by day 15, range 13-20 days). One patient had grade II skin GVHD and one developed grade IV disease but the other six patients had no acute GVHD. However, there was high morbidity and mortality from virus infections associated with a sluggish return of CD4 and CD8 T cells into the normal range. Four patients died from virus disease (CMV, n = 2; EBV, n = 1; adenovirus, n = 1) and the remaining patients had frequent documented viral illnesses during the first year. We conclude that improvement in the outcome of unrelated donor marrow transplantation will require strategies which prevent rejection and GVHD coupled with attempts to accelerate immune reconstitution.

Mixed-lineage leukemia and asynchronous antigen expression.

Considerable confusion exists regarding the definition of acute mixed-lineage leukemia. We have proposed a list of strict criteria, limiting the term acute mixed-lineage leukemia to those patients whose blast cells co-express lymphoid and myeloid characteristics. This system includes cytochemical, immunologic, molecular, and cytogenetic characteristics that are strongly associated with either lymphoid or myeloid lineages. As more information becomes available, the criteria for mixed-lineage leukemia will undoubtedly change. Identification of patients with mixed-lineage leukemia and metachronous leukemia (lineage switch) is important for determining the prognostic implications of these findings. Care must be taken in identifying cases of metachronous leukemia because of the increased incidence of second malignancies following aggressive therapy. Evidence of a recurrence of the original clone must be obtained before metachronous leukemia can be diagnosed. As with mixed-lineage and metachronous leukemias, the potential clinical and prognostic implications of lymphoid leukemias with antigenic asynchrony should be identified. The asynchronous antigen expression in leukemic lymphoblasts may provide a means for detecting minimal residual disease. Detection of minimal residual leukemia is possible because these blasts differ from the predominant population of normal lymphoid cells in their expression of cell surface markers. Study of the mechanisms that lead to these unusual leukemias may result in better understanding of the processes that underlie both normal hematopoietic differentiation and leukemogenesis. An understanding of these leukemias may also permit identification of cases that are destined to fail current therapies so that more intensive or selective therapy can be instituted for such children. Curing the 30% of children with ALL that relapse despite our best efforts should be one of the top priorities for pediatric oncologists.

A pilot study of continuous infusion Ara-C in combination with rhG-CSF in relapsed childhood acute myeloid leukemia.

Relapse in acute myeloid leukemia (AML) following intensive chemotherapy bears a bad prognosis. We treated 18 children with relapsed AML on two separate protocols that included continuous infusion (CI) of cytosine arabinoside (ara-C) (total dose 4gr-6gr/m2) over 96-120 hours. In an attempt to increase the fraction of blasts in S-phase and render them more sensitive to cell-cycle specific agents such as ara-C, 10 patients received 5mcg/kg rhG-CSF twice daily beginning 48 hours before and continuing through the duration of the CI ara-C (POG #9192 study). The percentage of cells is S phase before and after G-CSF administration was determined. In a second group of patients (n = 8) who received ara-C alone, endogenous concentrations of G-CSF and serial blood counts were measured (St Jude's R4 study). The rationale of the St Jude's R4 was to optimize the schedule of the second course of ara-C at a time when the patient's endogenous G-CSF concentration was increased and thus maximize the percent of cells captured in S phase. Four out of 8 patients receiving CI ara-C alone and 4 out of 10 patients receiving CI ara-C with rhG-CSF achieved a complete remission (CR) after 1 cycle of therapy. Four patients in CR underwent marrow transplantation (2 allogeneic and 2 autologous). Cell cycle analysis of blast cells cultured in vitro with or without G-CSF showed a two fold increase in the percentage of cells in S phase (P = 0.03) whereas cells obtained from patients before and after G-CSF administration showed no difference in cell cycling. Correlation between G-CSF concentrations and ANC showed a negative association indicating that the regulatory mechanisms for G-CSF production remained intact. In our relatively small series, CI ara-C achieved a CR rate of 44% with rhG-CSF having no effect on the remission rate. Although in vitro rhG-CSF increased the percentage of blasts in S phase significantly, in vivo effects were not observed. Larger studies with combinations of different hematopoietic growth factors and cell-cycle active drugs are needed to evaluate the role of these cytokines in the therapy of recurrent AML.

Removal of phenytoin by plasmapheresis in a patient with thrombotic thrombocytopenia purpura.

Phenytoin removal by plasmapheresis was evaluated in a 17-year-old girl with thrombotic thrombocytopenia purpura. Free and total phenytoin concentrations were measured in the patient's serum and in the plasma removed by plasmapheresis. Plasmapheresis was performed on three separate days with the removal of 4.7%, 3.3%, and 2.7% of total body stores. Free phenytoin concentration was similar in both the plasma removed by plasmapheresis and the patient's serum. Plasmapheresis did not significantly alter the serum concentration of phenytoin; dosage adjustments of phenytoin are therefore unnecessary.

Molecular alterations of the IDH1 gene in AML: a Children's Oncology Group and Southwest Oncology Group study.

Recent whole-genome sequencing efforts led to the identification of IDH1(R132) mutations in acute myeloid leukemia (AML) patients. We studied the prevalence and clinical implications of IDH1 genomic alterations in pediatric and adult AML. Diagnostic DNA from 531 AML patients treated on Children's Oncology Group trial COG-AAML03P1 (N=257), and Southwest Oncology Group trials SWOG-9031, SWOG-9333 and SWOG-9500 (N=274), were tested for IDH1 mutations. Codon R132 mutations were absent in the pediatric cohort, but were found in 12 of 274 adult patients (4.4%, 95% CI 2.3-7.5). IDH1(R132) mutations occurred most commonly in patients with normal karyotype, and those with FLT3/ITD and NPMc mutations. Patients with IDH1(R132) mutations trended toward higher median diagnostic white blood cell counts (59.2 x 10(9) vs 29.1 x 10(9) per liter, P=0.19) than those without mutations, but the two groups did not differ significantly in age, bone marrow blast percentage, overall survival or relapse-free survival. Eleven patients (2.1%) harbored a novel V71I sequence alteration, which was found to be a germ-line polymorphism. IDH1 mutations were not detected in pediatric AML, and are uncommon in adult AML.