Biomedical subjects

Susan M Chang

Publications and source records attributed to Susan M Chang.

At least 37 records · Page 2Linked to original sources

PubMed2005

Dynamic susceptibility contrast perfusion imaging of radiation effects in normal-appearing brain tissue: changes in the first-pass and recirculation phases.

PURPOSE: To identify radiation-induced changes in the cerebral vasculature of healthy tissue in the first four months following radiotherapy through the analysis of dynamic-susceptibility contrast perfusion imaging. MATERIALS AND METHODS: Dynamic gradient-echo imaging was performed on 22 patients during injection of a bolus of Gd-DTPA contrast. The relative cerebral blood volume (rCBV), maximum DeltaR2* of the first passage of the bolus, and a recirculation parameter were derived from gamma-variate fits of the dynamic data. The white matter (WM) rCBV and peak heights were estimated through correlation with segmented T1-weighted images. A percent recovery to baseline was also computed to further describe the recirculation phase. RESULTS: A significant elevation of the recirculation phase was observed at doses>15 Gy at two months following radiotherapy. This was reflected in an increased recirculation parameter in the fitted curves in the 15-30, 30-45, and >45 Gy dose groups to 2.8%, 3.8%, and 2.4% above the <15 Gy voxels, as well as in a decline in percent recovery to baseline. A trend toward lower rCBV and peak heights was observed at that same time point. CONCLUSION: The observed results suggest a dose-dependent decline in vessel density and increase in vascular permeability and/or tortuosity in irradiated normal-appearing brain tissue at two months following radiotherapy.

Adult↗

PubMed2005

Phase II study of CCI-779 in patients with recurrent glioblastoma multiforme.

PURPOSE: Loss of PTEN, which is common in glioblastoma multiforme (GBM), results in activation of the mammalian target of rapapmycin (mTOR), thereby increasing mRNA translation of a number of key proteins required for cell-cycle progression. CCI-779 is an inhibitor of mTOR. The primary objectives of this study were to determine the efficacy of CCI-779 in patients with recurrent GBM and to further assess the toxicity of the drug. EXPERIMENTAL DESIGN: CCI-779 was administered weekly at a dose of 250 mg intravenously for patients on enzyme-inducing anti-epileptic drugs (EIAEDs). Patients not on EIAEDs were initially treated at 250 mg; however, the dose was reduced to 170 mg because of intolerable side effects. Treatment was continued until unacceptable toxicity, tumor progression, or patient withdrawal. The primary endpoint was 6-month progression-free survival. RESULTS: Forty-three patients were enrolled; 29 were not on EIAEDs. The expected toxicity profile of increased lipids, lymphopenia, and stomatitis was seen. There were no grade IV hematological toxicities and no toxic deaths. One patient was progression free at 6 months. Of the patients assessable for response, there were 2 partial responses and 20 with stabilization of disease. The median time to progression was 9 weeks. CONCLUSIONS: CCI-779 was well tolerated at this dose schedule; however, there was no evidence of efficacy in patients with recurrent GBM. Despite initial disease stabilization in approximately 50% of patients, the durability of response was short. Because of the low toxicity profile, CCI-779 may merit exploration in combination with other modalities.

Adult↗

PubMed2005

Small molecule and monoclonal antibody therapies in neurooncology.

BACKGROUND: The prognosis for most patients with primary brain tumors remains poor. Recent advances in molecular and cell biology have led to a greater understanding of molecular alterations in brain tumors. These advances are being translated into new therapies that will hopefully improve the prognosis for patients with brain tumors. METHODS: We reviewed the literature on small molecule targeted agents and monoclonal antibodies used in brain tumor research and brain tumor clinical trials for the past 20 years. RESULTS: Brain tumors commonly express molecular abnormalities. These alterations can lead to the activation of cell pathways involved in cell proliferation. This knowledge has led to interest in novel anti-brain-tumor therapies targeting key components of these pathways. Many drugs and monoclonal antibodies have been developed that modulate these pathways and are in various stages of testing. CONCLUSIONS: The use of targeted therapies against brain tumors promises to improve the prognosis for patients with brain tumors. However, as the molecular pathogenesis of brain tumors has not been linked to a single genetic defect or target, molecular agents may need to be used in combinations or in tandem with cytotoxic agents. Further study of these agents in well-designed cooperative clinical trials is needed.

Antibodies, Monoclonal↗

PubMed2005

GNOSIS: guidelines for neuro-oncology: standards for investigational studies-reporting of phase 1 and phase 2 clinical trials.

We present guidelines to standardize the reporting of phase 1 and phase 2 neuro-oncology trials. The guidelines are also intended to assist with accurate interpretation of results from these trials, to facilitate the peer-review process, and to expedite the publication of important and accurate manuscripts. Our guidelines are summarized in a checklist format that can be used as a framework from which to construct a phase 1 or 2 clinical trial.

Clinical Trials, Phase I as Topic↗

PubMed2005

Neuroradiographic changes following convection-enhanced delivery of the recombinant cytotoxin interleukin 13-PE38QQR for recurrent malignant glioma.

OBJECT: Convection-enhanced delivery (CED) is a novel method for delivering therapeutic agents to infiltrative brain tumor cells. For agents administered by CED, changes on magnetic resonance (MR) imaging directly resulting from catheter placement, infusion, and the therapeutic compound may confound any interpretation of tumor progression. As part of an ongoing multiinstitutional Phase I study, 14 patients with recurrent malignant glioma underwent CED of interleukin (IL) 13-PE38QQR, a recombinant cytotoxin consisting of human IL-13 conjugated with a truncated Pseudomonas exotoxin. Serial neuroradiographic changes were assessed in this cohort of patients. METHODS: Patients were treated in two groups: Group 1 patients received IL13-PE38QQR before and after tumor resection; Group 2 patients received infusion only after tumor resection. Preoperative and postinfusion MR images were obtained prospectively at specified regular intervals. Changes were noted along catheter tracks on postresection MR images obtained in all patients. A simple grading system was developed to describe these changes. When MR imaging changes appeared to be related to IL1 3-PE38QQR, patients were followed up without instituting new antitumor therapy. CONCLUSIONS: As CED of therapeutic agents becomes more common, clinicians and investigators must become aware of associated neuroimaging changes that should be incorporated into toxicity assessment. We have developed a simple grading system to facilitate communication about these changes among investigators. Biological imaging modalities that could possibly distinguish these changes from recurrent tumor should be evaluated. In this study the authors demonstrate the challenges in determining efficacy when surrogate end points such as time to tumor progression as defined by new or progressive contrast enhancement on MR imaging are used with this treatment modality.

ADP Ribose Transferases↗

PubMed2005

Prognostic significance of intracranial dissemination of glioblastoma multiforme in adults.

OBJECT: The clinical outcome and treatment of adult patients with disseminated intracranial glioblastoma multiforme (GBM) is unclear. The objective in the present study was to assess the prognostic significance of disseminated intracranial GBM in adults at presentation and at the time of tumor progression. METHODS: Clinical data from 1491 patients older than 17 years and harboring a GBM that had been diagnosed between 1988 and 1998 at the University of California at San Francisco neurooncology clinic were retrospectively reviewed. Dissemination of the GBM (126 patients) was determined based on Gd-enhanced magnetic resonance images. Classification of dissemination was as follows: Type I, single lesion with subependymal or subarachnoid spread; Type II, multifocal lesions without subependymal or subarachnoid spread; and Type III, multifocal lesions with subependymal or subarachnoid spread. Subgroups of patients were compared using Kaplan-Meier curves that depicted survival probability. The median postprogression survival (PPS), defined according to neuroimaging demonstrated dissemination, was 37 weeks for Type I (23 patients), 25 weeks for Type II (50 patients), and 10 weeks for Type III spread (19 patients). Patients with dissemination at first tumor progression (52 patients) overall had a shorter PPS than those in a control group with local progression, after adjusting for age, Kamofsky Performance Scale score, and time from tumor diagnosis to its progression (311 patients). When analyzed according to tumor dissemination type, PPS was significantly shorter in patients with Type II (33 patients, p < 0.01) and Type III spread (11 patients, p < 0.01) but not in those with Type I spread (eight patients, p = 0.18). CONCLUSIONS: Apparently, the presence of intracranial tumor dissemination on initial diagnosis does not in itself preclude aggressive treatment if a patient is otherwise well. A single focus of GBM that later demonstrates Type I dissemination on progression does not have a worse prognosis than a lesion that exhibits only local recurrence.

Adult↗

PubMed2005

Serial diffusion-weighted magnetic resonance imaging in cases of glioma: distinguishing tumor recurrence from postresection injury.

OBJECT: Diffusion-weighted magnetic resonance (MR) imaging is an invaluable tool in the diagnosis of acute stroke and other types of brain injury. Abnormalities in and around the resection cavity on diffusion-weighted imaging have been observed following surgery for infiltrating glioma. The purpose of this study was to investigate prospectively the incidence, time course, and ultimate outcome of these abnormalities. METHODS: Forty-four consecutive patients with newly diagnosed gliomas were prospectively observed using serial MR imaging including diffusion-weighted sequences. Clinical and surgical data were also collected. Immediately postoperatively neuroimaging identified 28 patients (64%) in whom areas of reduced diffusion appeared in or around the resection cavity (mean volume 8.2 +/- 1.5 cm3). Complete resolution of this reduced diffusion was demonstrated within 90 days in 24 patients (86%). On subsequent neuroimages these areas demonstrated Gd enhancement as early as postoperative Day 15 and as late as Day 198 and ultimately took on the appearance of encephalomalacia in 26 (93%) of 28 cases. Postoperative reduced diffusion was not predicted by the clinical or surgical parameters that were assessed. No clinical deficits were attributable to the reduced diffusion. CONCLUSIONS: An abnormality related to diffusion-weighted sequences on postoperative MR imaging can occur after resection of newly diagnosed gliomas. In this study the abnormality typically resolved and was replaced by contrast enhancement on follow-up imaging, ultimately demonstrating encephalomalacia on long-term follow up. Findings on neuroimaging during the period of enhancement could be confused with recurrent tumor and interpreted as early treatment failure. Based on the findings of this study the authors strongly suggest that the inclusion of diffusion-weighted sequences in postoperative MR imaging is essential, as is MR imaging immediately before radiation therapy to monitor disease progression. A new enhancement observed after glioma surgery should be interpreted in the context of the diffusion-weighted image obtained immediately postoperatively.

Adult↗

PubMed2005

Relationship of MR-derived lactate, mobile lipids, and relative blood volume for gliomas in vivo.

BACKGROUND AND PURPOSE: Gliomas are heterogeneous tumors with increased microvasculature, hypoxia, and necrosis. The purpose of this study was to examine the distribution and relationship of the MR-derived relative cerebral blood volume (rCBV), lactate (Lac), and mobile lipids (Lip), which have been proposed as markers for these phenomena of gliomas in vivo. METHODS: Twenty-three patients with newly diagnosed gliomas were examined before surgical biopsy and/or resection (seven grade II, five grade III, and 11 grade IV), and 27 patients were studied after surgery but before radiation treatment and/or chemotherapy (11 grade II, two grade III, and 14 grade IV gliomas). Lac and Lip were estimated from Lac-edited three-dimensional MR spectroscopic images. Dynamic susceptibility-contrast MR imaging was applied to obtain perfusion-weighted images and rCBV maps. RESULTS: Before surgical biopsy/resection, one low-grade and 12 of 16 high-grade gliomas had significantly elevated Lac. No low-grade and 10 of 16 high-grade gliomas had significantly elevated Lip. In presurgical high-grade gliomas, volumes of elevated Lip and macronecrosis were significantly correlated. rCBV was significantly increased in regions with elevated Lac. After we excluded macronecrosis, the rCBV for regions with elevated Lip but no Lac was significantly higher than rCBV in regions with elevated Lac but no Lip. After surgical biopsy/resection, more low-grade patients showed significantly elevated Lac and Lip than before. CONCLUSION: The in vivo distribution of rCBV, Lac, and Lip, as evaluated with three-dimensional MR spectroscopic imaging, may help in the diagnosis and selection of the most appropriate therapy for patients with gliomas.

Blood Volume↗

PubMed2004

Phase II study of fenretinide (NSC 374551) in adults with recurrent malignant gliomas: A North American Brain Tumor Consortium study.

PURPOSE: Fenretinide induces apoptosis in malignant gliomas in vitro. This two-stage phase II trial was conducted to determine the efficacy of fenretinide in adults with recurrent malignant gliomas. PATIENTS AND METHODS: Twenty-two patients with anaplastic gliomas (AG) and 23 patients with glioblastoma (GBM) whose tumors had recurred after radiotherapy and no more than two chemotherapy regimens were enrolled. Fenretinide was given orally on days 1 to 7 and 22 to 28 in 6-week cycles in doses of 600 or 900 mg/m(2) bid. RESULTS: Six of 21 (29%) patients in the AG arm and two of 23 (9%) patients in the GBM arm had stable disease at 6 months. One patient with AG treated at 900 mg/m(2) bid dosage had a partial radiologic response. Median progression-free survival (PFS) was 6 weeks for the AG arm and 6 weeks for the GBM arm. PFS at 6 months was 10% for the AG arm and 0% for the GBM arm. Grade 1 or 2 fatigue, dryness of skin, anemia, and hypoalbuminemia were the most frequent toxicities reported. The trial was closed after the first stage because of the inadequate activity at the fenretinide doses used. The first-administration mean plasma C(max) for fenretinide was 832 +/- 360 ng/mL at the 600 mg/m(2) bid dosage and 1,213 +/- 261 ng/mL at the 900 mg/m(2) bid dosage. CONCLUSION: Fenretinide was inactive against recurrent malignant gliomas at the dosage used in this trial. However, additional studies using higher doses of the agent are warranted based on the tolerability of the agent and the potential for activity of a higher fenretinide dosage, as suggested in this trial.

Administration, Oral↗

PubMed2004

Phase II study of temozolomide and thalidomide with radiation therapy for newly diagnosed glioblastoma multiforme.

PURPOSE: The chemotherapeutic agent temozolomide (TMZ) and the antiangiogenic agent thalidomide have both demonstrated antitumor activity in patients with recurrent malignant glioma. The objectives of this study were to determine if the combined strategy of these oral agents with radiation therapy (RT) is associated with an improved median survival of patients with newly diagnosed glioblastoma multiforme and to evaluate toxicity. METHODS AND MATERIALS: Sixty-seven patients were enrolled in this trial. Radiotherapy parameters were a total dose of 60 Gy delivered in 2 Gy fractions over 6 weeks. Temozolomide was administered starting the first day of RT at 150 mg/m(2) daily for 5 days every 4 weeks for the first cycle and escalated to a maximum dose of 200 mg/m(2). Thalidomide was started on Day 7 of RT at 200 mg and escalated by 100-200 mg every 1-2 weeks depending on patient tolerance, to a maximum of 1,200 mg daily. RESULTS: Sixty-one patients have progressed, with a median time to progression of 22 weeks. Fifty-six patients have died, and the median survival was 73 weeks. CONCLUSIONS: This strategy of combination TMZ, thalid and RT was relatively well tolerated with favorable survival outcome for patients with GM when compared to patients not treated with adjuvant chemotherapy and similar to those who have received nitrosourea adjuvant chemotherapy. It is unclear the added advantage thalid has in combination with TMZ for this patient population.

Adult↗

PubMed2004

Phase I study pilot arms of radiotherapy and carmustine with temozolomide for anaplastic astrocytoma (Radiation Therapy Oncology Group 9813): implications for studies testing initial treatment of brain tumors.

PURPOSE: To determine the safety and toxicity of carmustine (BCNU) and temozolomide (TMZ) with radiotherapy (RT) in newly diagnosed anaplastic astrocytoma. METHODS AND MATERIALS: Patients >18 years old with anaplastic astrocytoma, a Karnofsky performance status score of > or =60, and adequate pulmonary function were eligible. All patients provided informed consent. Standard RT started within 5 weeks of diagnosis. In both arms, 150 mg/m(2) of TMZ was given on Days 1-5 of RT. In Arm 1, 200 mg/m(2) of carmustine was given on Day 1 of RT. In Arm 2, 150 mg/m(2) of carmustine was given on Day 5 of RT. After RT, TMZ and carmustine were repeated for a total of six cycles. RESULTS: A total of 15 and 14 patients were enrolled in the two pilot arms. Because of hematologic and pulmonary toxicities, dose reductions by the second cycle of therapy occurred in >70% of the patients in Arm 1 and >50% in Arm 2 despite a reduction in the carmustine dose. CONCLUSION: The results of these pilot studies have implications for the design of studies testing the initial treatment of brain tumors. Because of the poor tolerance of the combination, the multicooperative group Phase III study consists of two randomized arms of single-agent carmustine vs. single-agent TMZ.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2004

Phase II study of neoadjuvant 1, 3-bis (2-chloroethyl)-1-nitrosourea and temozolomide for newly diagnosed anaplastic glioma: a North American Brain Tumor Consortium Trial.

BACKGROUND: Temozolomide (TMZ) and 1, 3-bis (2-chloroethyl)-1-nitrosourea (BCNU) are reported to be active agents in anaplastic glioma (AG). TMZ has also been shown to deplete alkyltransferase, a DNA repair enzyme that contributes to nitrosourea resistance. The objective of the current study was to determine the efficacy and toxicity profile of a combination of these agents before radiotherapy in newly diagnosed AG. METHODS: Eligibility criteria included histologically confirmed newly diagnosed AG with measurable enhancing disease, a Karnofsky performance score (KPS) > or = 60, normal pulmonary function, and normal laboratory parameters. In addition, informed consent was obtained from all patients. BCNU given at a dose of 150 mg/m(2) intravenously was followed after 2 hours by TMZ given at a dose of 550 mg/m(2) orally on Day 1 of a 42-day cycle to a maximum of 4 cycles, unless there was tumor progression or unacceptable toxicity. RESULTS: Forty-one eligible patients were accrued. Their median age was 40 years. Seventy-six percent of patients had a KPS of 90-100. The histology was 81% anaplastic astrocytoma, 12% anaplastic oligodendroglioma, and 7% mixed tumors. Twenty-two percent of patients did not complete 4 cycles because of toxicity, mainly hematologic. Forty-six percent of patients experienced Grade 3 or 4 (according to National Cancer Institute Common Toxicity Criteria) thrombocytopenia. Twenty percent had Grade 4 granulocytopenia. Two patients died while receiving therapy, 1 of progressive disease and the other of Pneumocystis carinii pneumonia. The complete and partial response rates were 2% and 27% respectively. An additional 54% of patients had stable disease. Seventeen percent developed progressive disease (10% after the first cycle and 7% after the second cycle). CONCLUSIONS: This neoadjuvant strategy was associated with significant myelosuppression and a modest response rate in patients with newly diagnosed AG.

Adolescent↗

PubMed2004

Temozolomide in the treatment of recurrent malignant glioma.

BACKGROUND: Options for chemotherapy at the time of recurrence in patients with malignant glioma are limited. The authors describe the efficacy and safety results of their institution's open-label, compassionate-use protocol of temozolomide for patients with recurrent malignant glioma. METHODS: Patients with recurrent malignant glioma at any time during recurrence were treated with oral temozolomide at a dose of 150 mg/m2 per day on a 5-day schedule every 28 days. If this dose was tolerated, then escalation to 200 mg/m2 was allowed. Clinical evaluations and assessments of tumor response were performed every 2 months. All patients or their surrogates signed approved Institutional Review Board consent forms. RESULTS: Among 213 patients who were treated, 33% had Grade 3 tumors, and 67% had Grade 4 tumors. The overall objective response rate was 16% in both of these patient groups; and an additional 51% and 30% of patients with Grade 3 and Grade 4 tumors, respectively, had stable disease as their best response. The 6-month progression-free survival rates were 41% and 18% for patients with Grade 3 and Grade 4 tumors, respectively. The median survival was 49 weeks for patients with Grade 3 tumors and 32 weeks for patients with Grade 4 tumors. The major toxicity was hematologic toxicity. In multivariate analysis, the Karnofsky performance score was a significant predictor of survival for patients with Grade 4 tumors. CONCLUSIONS: Temozolomide was well tolerated in patients with recurrent malignant glioma and had modest efficacy, even at the time of multiple recurrences.

Adolescent↗

PubMed2004

Phase I/pharmacokinetic study of CCI-779 in patients with recurrent malignant glioma on enzyme-inducing antiepileptic drugs.

OBJECTIVES: CCI-779 is an ester of the immunosuppressive agent sirolimus (rapamycin) that causes cell-cycle arrest at G1 via inhibition of key signaling pathways resulting in inhibition of RNA translation. Antitumor activity has been demonstrated using cell lines and animal models of malignant glioma. Patients receiving enzyme-inducing anti-epileptic drugs (EIAEDs) can have altered metabolism of drugs like CCI-779 that are metabolized through the hepatic cytochrome P450 enzyme system. The objectives of this study were to determine the pharmacokinetic profile and the maximum tolerated dose of CCI-779 in patients with recurrent malignant gliioma taking EIAEDs. STUDY DESIGN: The starting dose of CCI-779 was 250 mg intravenously (IV) administered weekly on a continuous basis. Standard dose escalation was performed until the maximum tolerated dose was established. Toxicity was assessed using the National Cancer Institute common toxicity criteria. RESULTS: Two of 6 patients treated at the second dose level of 330 mg sustained a dose-limiting toxicity: grade III stomatitis, grade 3 hypercholesterolemia, or grade 4 hypertriglyceridemia. The maximum tolerated dose was reached at 250 mg IV. Pharmacokinetic profiles were similar to those previously described, but the area under the whole blood concentration-time curve of rapamycin was 1.6 fold lower for patients on EIAEDs. CONCLUSIONS: The recommended phase II dose of CCI 779 for patients on enzyme-inducing antiepileptic drugs is 250 mg IV weekly. A phase II study is ongoing to determine the efficacy of this agent.

Adult↗

PubMed2004

Central neurocytoma: a review.

Central neurocytomas are rare intraventricular neoplasms of the central nervous system, compromising 0.25-0.5% of brain tumors. The diagnosis and management of these tumors remains controversial since most clinical series are small. Typically, patients with central neurocytomas have a favorable prognosis, but in some cases the clinical course is more aggressive. Although histological features of anaplasia do not predict biologic behavior, proliferation markers including MIB-1 might be more useful in predicting relapse. The most important therapeutic modality is surgery, and a safe maximal resection confers the best long-term outcome. In cases of a subtotal resection,'standard external beam radiation can be added or radiation can be delayed until tumor progression occurs. Smaller residual tumor volumes or recurrences can be treated with more conformal radiation or focused radiosurgery. Re-operation for recurrence should be considered if the procedure can be safely performed. Chemotherapy may be useful for recurrent central neurocytomas that cannot be resected and have been radiated, although long-term responses have not been reported for chemotherapy. Overall, this paper reviews the findings of the larger studies and highlights some of the important case reports that contribute to the current management of central neurocytomas.

Brain Neoplasms↗

PubMed2004

Brain metastases.

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Antineoplastic Agents↗

PubMed2004

Psychosocial intervention improves the development of term low-birth-weight infants.

It is estimated that 11% of births in developing counties are term low-birth-weight (LBW); however, there is limited information on the development of these infants. Our objectives were to determine the effect of psychosocial intervention on the development of LBW infants and to compare term LBW and normal-birth-weight (NBW) infants. Term LBW (n = 140) and NBW infants (n = 94) were enrolled from the main maternity hospital in Kingston, Jamaica. The LBW infants were randomly assigned to control or intervention comprising weekly home visits from birth to 8 wk and from 7 to 24 mo of age. Development was assessed at 15 and 24 mo with the Griffiths Scales. The intervention benefited the infants' developmental quotient (DQ, P < 0.05) and performance subscale at 15 mo (P < 0.02), the hand and eye (P < 0.05) and performance subscales (P < 0.02) at 24 mo, and home environment at 12 mo. The effect of the intervention on development was mediated in part by the improvement in the home environment. The control LBW infants had significantly lower scores than the NBW in DQ and several subscales, whereas there were no significant differences between the NBW and the LBW infants after intervention. In conclusion, term LBW was associated with developmental delays, which were reduced with psychosocial intervention.

Child Development↗

PubMed2004

O6-benzylguanine suppression of O6-alkylguanine-DNA alkyltransferase in anaplastic gliomas.

The purpose of the study was to determine the dose of O(6)-benzylguanine (BG) that would suppress O(6)-alkylguanine-DNA alkyltransferase (AGT) activity to undetectable levels in > 90% of anaplastic gliomas, as measured 6 h after a 1-h BG infusion. Subjects who were scheduled for surgical resection of a known or presumed anaplastic glioma received a 1-h infusion of BG. Tumor tissue was surgically removed approximately 6 h after the end of the infusion and was analyzed for AGT activity. The BG dose was escalated until at least 11 of 14 subjects had no detectable AGT activity. An additional cohort of patients received the identified effective dose of BG approximately 18 h before tumor resection in order to compare our results with an earlier study using the longer time interval. In the 79 subjects who were enrolled, there was no significant toxicity that was attributed to the BG. A dose-response relationship was determined between the BG dose and the percentage of subjects with undetectable AGT. A dose of 120 mg/m(2) suppressed AGT to less than detectable levels in 17 of 18 patients when the drug-resection interval was 6 h. With an 18-h interval, only 5 of 11 subjects had undetectable AGT at the 120-mg/m(2) dose. We conclude that a BG dose of 120 mg/m(2) given 6 h before an alkylating drug would be effective in suppressing AGT and possibly potentiating the cytotoxic effects of the drug.

Adult↗