ABTC-0904: targeting glioma stem cells in GBM: a phase 0/II study of hedgehog pathway inhibitor GDC-0449.

PURPOSE: Gliomagenesis and resistance of glioblastoma (GBM) are believed to be mediated by glioma stem cells (GSC). Evidence suggests that SHH signaling promotes GSC proliferation and self-renewal. METHODS: ABTC-0904 was a two-arm, multicenter phase 0/II study of GDC-0449, an oral inhibitor of Smoothened (SMO) in patients undergoing resection for recurrent GBM. All patients (Arms I and II) had surgery and received drug post-operatively. Only patients in Arm I received drug prior to surgery. The primary objective was to determine 6-month progression free survival (PFS-6). Secondary endpoints include median PFS (mPFS) and overall survival (mOS), response rate, and toxicity. Correlative studies included bioanalysis of GDC-0449, and inhibition of SHH signaling, GSC proliferation and self-renewal. RESULTS: Forty-one patients were enrolled. Pharmacokinetics of GDC-0449 in plasma demonstrated levels within expected therapeutic range in 75% of patients. The proportion of tumorcells producing CD133+ neurospheres, neurosphere proliferation, self-renewal, and expression of the SHh downstream signaling was significantly decreased in Arm I following GDC-0449 treatment (p < 0.005; p < 0.001 respectively) compared to Arm II (no drug pre-op). Treatment was well tolerated. There were no objective responders in either arm. Overall PFS-6 was 2.4% (95% CI 0.9-11.1%). Median PFS was 2.3 months (95% CI 1.9-2.6) and mOS was 7.8 months (95% CI 5.4-10.1). CONCLUSIONS: GDC-0449 was well tolerated, reached tumor, and inhibited CD133+ neurosphere formation, but had little clinical efficacy as a single agent in rGBM. This suggests growth and maintenance of rGBM is not solely dependent on the SHH pathway thus targeting SMO may require combined approaches.

Phase I trial of aflibercept (VEGF trap) with radiation therapy and concomitant and adjuvant temozolomide in patients with high-grade gliomas.

Anti-vascular endothelial growth factor (VEGF) therapy has shown promise in the treatment of high-grade gliomas (HGG). Aflibercept is a recombinant human fusion protein that acts as a soluble decoy receptor for VEGF-A, VEGF-B and placental growth factor, depleting circulating levels of these growth factors. The Adult Brain Tumor Consortium conducted a phase I trial of aflibercept and temozolomide (TMZ) in patients with newly diagnosed HGG with 2 dose levels and a 3+3 design. Three arms using aflibercept were examined; with radiation and concomitant temozolomide; with adjuvant temozolomide using the 5/28 regimen; and with adjuvant temozolomide using the 21/28 day regimen. Fifty-nine patients were enrolled, 21 in arm 1, 20 in arm 2 and 18 in arm 3. Median age was 56 years (24-69); median KPS 90 (60-100). The maximum tolerated dose (MTD) of aflibercept for all 3 arms was 4 mg/kg every 2 weeks. Dose limiting toxicities at the MTD were: Arm 1: 0/21 patients; Arm 2: 2/20 patients (G3 deep vein thrombosis, G4 neutropenia; Arm 3: 3/18 patients) (G4 biopsy-confirmed thrombotic microangiopathy, G3 rash, G4 thrombocytopenia). The median number of cycles of aflibercept was 5 (range, 1-16). All patients stopped treatment; 28 (47%) for disease progression, 21 (36%) for toxicities, 8 (14%) for other reasons, and 2 (3%) patients completed the full treatment course. This study met its primary endpoint and the MTD of aflibercept with radiation and concomitant and adjuvant temozolomide is 4 mg/kg every 2 weeks.

A prospective multicenter study of venous thromboembolism in patients with newly-diagnosed high-grade glioma: hazard rate and risk factors.

Venous thromboembolism (VTE) is a common complication in patients with high-grade gliomas. The purpose of this prospective multicenter study was to determine the hazard rate of first symptomatic VTE in newly-diagnosed glioma patients and identify clinical and laboratory risk factors. On enrollment, demographic and clinical information were recorded and a comprehensive coagulation evaluation was performed. Patients were followed until death. The study end point was objectively-documented symptomatic VTE. One hundred seven patients were enrolled with a median age of 57 years (range 29-85) between June 2005 and April 2008. Ninety-one (85 %) had glioblastoma multiforme (GBM). During an average survival of 17.7 months, 26 patients (24 %) (95 % CI 17-34 %) developed VTE (hazard rate 0.15 per person-year) and 94 patients (88 %) died. Median time to VTE was 14.2 weeks post-operation (range 3-126). Patients with an initial tumor biopsy were 3.0 fold more likely to suffer VTE (p = 0.02). Patients with an elevated factor VIII activity (>147 %) were 2.1-fold more likely to develop VTE. ABO blood group, D dimer and thrombin generation were not associated with VTE. No fatal VTE occurred. VTE is a common complication in patients with newly-diagnosed high grade gliomas, particularly in the first six months after diagnosis. Patients with an initial tumor biopsy and elevated factor VIII levels are at increased risk. However, VTE was not judged to be primarily responsible for any patient deaths. Therefore, outpatient primary VTE prophylaxis remains investigational until more effective primary prophylaxis strategies and therapies for glioma are identified.

Clinical trials of R-(-)-gossypol (AT-101) in newly diagnosed and recurrent glioblastoma: NABTT 0602 and NABTT 0702.

PURPOSE: AT-101 is an oral bcl-2 family protein inhibitor (Bcl-2, Bcl-XL, Mcl-1, Bcl-W) and potent inducer of proapoptotic proteins. A prior study of the parent compound, racemic gossypol, demonstrated objective and durable responses in patients with malignant glioma. AT-101 has demonstrated synergy with radiation in animal models. The objectives of trial NABTT 0602 were to determine the MTD of AT-101 concurrent with temozolomide (TMZ) and radiation therapy (RT) (Arm I) and to determine the MTD of AT-101 when given with adjuvant TMZ after completion of standard chemoradiation (Arm 2). Separately in trial NABTT 0702, the survival and response rates of single agent AT-101 were evaluated in patients with recurrent glioblastoma. METHODS: In NABTT 0602 Phase I, a 3+3 design was used to define MTDs after maximal safe resection, patients with newly diagnosed glioblastoma received standard concurrent RT (60 Gy) and TMZ 75 mg/m2/day followed by adjuvant TMZ 150-200 mg/m2 days 1-5 in 28-day cycles (Stupp regimen). In Arm I, AT-101 was administered M-F during the six weeks of RT beginning 20 mg qd. In Arm 2, concurrent with each adjuvant cycle of TMZ, AT-101 was administered at a starting dose of 20 mg, days 1-21 followed by 7-day break for a maximum of 6 cycles. The PK blood samples were collected in the first three patients in each cohort of arm 1. In NABTT 0702 patients with recurrent glioblastoma received 20 mg p.o. per day for 21 of 28 days in repeated cycles to assess overall survival (OS). RESULTS: A total of sixteen patients were enrolled on the two study arms of NABTT 0602. In Arm 1 AT-101 was escalated from 20 to 30 mg where one of six patients experienced DLT (grade 3 GI ulcer). On Arm 2 one patient treated at 20 mg experienced DLT (grade 3 ileus, nausea and diarrhea). The cohort was expanded to include seven patients without observation of DLT. PK results were consistent with drug levels from non-CNS studies. At study closure six patients are still alive. The median survival times for Arm I and Arm II are 15.2 months and 18.2 months, respectively. In NABTT 0702 fifty-six patients were enrolled and forty-three were eligible for imaging response. Sixteen patients (29%) had stable disease as best response and one partial response was observed. The median OS with single agent AT-101 was 5.7 months (95%CI: 3.8-7.6 months) for patients with rGBM. CONCLUSIONS: AT-101 can be safely administered with radiation therapy and TMZ in patients with newly diagnosed glioblastoma without toxicity unique to patients with CNS tumors. Because of toxicity observed in non-CNS AT-101 clinical trials, further dose-escalation was not attempted. The recommended dose for future studies that utilize continual AT-101 exposure is 20 mg days M-F concurrent with RT/TMZ and 20 mg days 1-21 for each 28-day cycle of TMZ. AT-101 has limited activity as a single agent in unselected patients with recurrent glioblastoma. Future trials should attempt to better understand resistance mechanisms and consider combination therapy.

Lisavanbulin (BAL101553), a novel microtubule inhibitor, plus radiation in patients with newly diagnosed, MGMT promoter unmethylated glioblastoma.

Background: Lisavanbulin (BAL101553) is a small, lipophilic, oral microtubule destabilizer with promising antitumoral activity observed in preclinical glioblastoma (GBM) models. Methods: This multicenter phase 1 study sought to determine the MTD of oral Lisavanbulin in combination with standard RT (60 Gy/30 fractions) but without temozolomide in patients with newly diagnosed MGMT promoter unmethylated GBM (uGBM). Dose escalation followed a modified 3 + 3 design. Secondary objectives included estimation of OS and PFS and pharmacokinetic analysis. Results: Twenty-six patients with uGBM (median age, 63 years, 42.3% male, 61.5% with gross total resection, median Karnofsky performance status 80) were enrolled; 2 tumors had an IDH1 mutation. Predefined dose levels of Lisavanbulin, administered daily concomitantly with RT, were: 4 mg (5 pts), 6 mg (5 pts), 8 mg (7 pts), 12 mg (5 pts), and 15 mg (4 pts). The initial starting dose was 8 mg. Due to grade 4 aseptic meningoencephalitis in the first patient, the dose was decreased to 4 mg. Dose escalation resumed and continued to 15 mg with dose-limiting toxicities of grade 2 confusion and memory impairment observed at 12 mg. Avanbulin exposures increased in a relatively dose-proportional manner with increasing oral dose of Lisavanbulin from 4 to 15 mg. Conclusions: Lisavanbulin in combination with RT was considered safe up to the highest predefined oral dose level of 15 mg daily.

Response Rate and Molecular Correlates to Encorafenib and Binimetinib in BRAF-V600E Mutant High-Grade Glioma.

PURPOSE: Although fewer than 5% of high-grade gliomas (HGG) are BRAF-V600E mutated, these tumors are notable as BRAF-targeted therapy shows efficacy for some populations. The purpose of this study was to evaluate response to the combination of encorafenib with binimetinib in adults with recurrent BRAF-V600-mutated HGG. PATIENTS AND METHODS: In this phase 2, open-label, Adult Brain Tumor Consortium (ABTC) trial (NCT03973918), encorafenib and binimetinib were administered at their FDA-approved doses continuously in 28-day cycles. Eligible patients were required to have HGG or glioblastoma with a BRAF-V600E alteration that was recurrent following at least one line of therapy, including radiotherapy. RESULTS: Five patients enrolled between January 2020 and administrative termination in November 2021 (due to closure of the ABTC). Enrolled patients received treatment for 2 to 40 months; currently one patient remains on treatment. Centrally determined radiographic response rate was 60%, with one complete response and two partial responses. Methylation profiling revealed that all tumors cluster most closely with anaplastic pleomorphic xanthoastrocytoma (PXA). Transcriptional profile for MAPK-response signature was similar across all tumors at baseline and did not correlate with response in this small population. Circulating tumor DNA measured in plasma samples before treatment, during response, and upon progression showed feasibility of detection for the BRAF-V600E alteration. No new safety signal was detected. CONCLUSIONS: Encorafenib and binimetinib exhibit positive tumor responses in patients with recurrent BRAF-V600E mutant HGG in this small series, warranting therapeutic consideration. Although toxicity remains a concern for BRAF-targeted therapies, no new safety signal was observed in these patients.

Surgical window of opportunity trial reveals mechanisms of response and resistance to navtemadlin (KRT-232) in patients with recurrent glioblastoma.

We investigated the effectiveness of navtemadlin (KRT-232) in treating recurrent glioblastoma. A surgical window-of-opportunity trial ( NCT03107780 ) was conducted on 21 patients to determine achievable drug concentrations within tumor tissue and examine mechanisms of response and resistance. Both 120 mg and 240 mg daily dosing achieved a pharmacodynamic impact. Sequencing of three recurrent tumors revealed an absence of TP53 -inactivating mutations, indicating alternative mechanisms of resistance. In patient-derived GBM models, the lower range of clinically achieved navtemadlin concentrations induced partial tumor cell death as monotherapy. However, combining navtemadlin with temozolomide increased apoptotic rates while sparing normal bone marrow cells in vitro, which in return underwent reversible growth arrest. These results indicate that clinically achievable doses of navtemadlin generate significant pharmacodynamic effects and suggest that combined treatment with standard-of-care DNA damaging chemotherapy is a route to durable survival benefits. Statement of significance: Tissue sampling during this clinical trial allowed us to assess mechanisms of response and resistance associated with navtemadlin treatment in recurrent GBM. We report that clinically achievable doses of navtemadlin induce pharmacodynamic effects in tumor tissue, and suggest combinations with standard-of-care chemotherapy for durable clinical benefit.

A safety run-in and randomized phase 2 study of cilengitide combined with chemoradiation for newly diagnosed glioblastoma (NABTT 0306).

BACKGROUND: Cilengitide is a selective integrin inhibitor that is well tolerated and has demonstrated biologic activity in patients with recurrent malignant glioma. The primary objectives of this randomized phase 2 trial were to determine the safety and efficacy of cilengitide when combined with radiation and temozolomide for patients with newly diagnosed glioblastoma multiforme and to select a dose for comparative clinical testing. METHODS: In total, 112 patients were accrued. Eighteen patients received standard radiation and temozolomide with cilengitide in a safety run-in phase followed by a randomized phase 2 trial with 94 patients assigned to either a 500 mg dose group or 2000 mg dose group. The trial was designed to estimate overall survival benefit compared with a New Approaches to Brain Tumor Therapy (NABTT) Consortium internal historic control and data from the published European Organization for Research and Treatment of Cancer (EORTC) trial EORTC 26981. RESULTS: Cilengitide at all doses studied was well tolerated with radiation and temozolomide. The median survival was 19.7 months for all patients, 17.4 months for the patients in the 500 mg dose group, 20.8 months for patients in the 2000 mg dose group, 30 months for patients who had methylated O6-methylguanine-DNA methyltransferase (MGMT) status, and 17.4 months for patients who had unmethylated MGMT status. For patients aged ≤70 years, the median survival and survival at 24 months was superior to what was observed in the EORTC trial (20.7 months vs 14.6 months and 41% vs 27%, respectively; P = .008). CONCLUSIONS: Cilengitide was well tolerated when combined with standard chemoradiation and may improve survival for patients newly diagnosed with glioblastoma multiforme regardless of MGMT methylation status. The authors concluded that, from an efficacy and safety standpoint, future trials of this agent in this population should use the 2000 mg dose.

Phase I and pharmacokinetic study of COL-3 in patients with recurrent high-grade gliomas.

COL-3 is a chemically modified tetracycline that targets multiple aspects of matrix metalloproteinase regulation. This phase I clinical trial was conducted to determine the maximum tolerated dose (MTD) of COL-3 in adults with recurrent high-grade glioma, to describe the effects of enzyme-inducing antiseizure drugs (EIADs) on its pharmacokinetics, and to obtain preliminary evidence of activity. Adults with recurrent high-grade glioma were stratified by EIAD use. COL-3 was given orally daily without interruption until disease progression or treatment-related dose-limiting toxicity (DLT). Three patients in each EIAD group were evaluated at each dose level beginning with 25 mg/m(2)/day and escalated by 25 mg/m(2)/day. Toxicity, response, and pharmacokinetics were assessed. Thirty-three patients were evaluated. The MTD was 75 mg/m(2)/day in the -EIAD patients while one was not determined in +EIAD patients. The common toxicities observed were anemia, ataxia, diarrhea, hypokalemia, CNS hemorrhage, and myalgia. One partial response was observed. -EIAD patients tended to have a higher steady-state trough concentration that was apparent only at the 100 mg/m(2)/day dose level (P = 0.01). This study suggests that: (a) EIAD use does affect the pharmacokinetics of COL-3 at higher doses; and (b) there was not enough suggestion of single-agent activity to warrant further study in recurrent high-grade gliomas.

A phase I/II trial and pharmacokinetic study of ixabepilone in adult patients with recurrent high-grade gliomas.

Ixabepilone is an epothilone, a novel class of non-taxane microtubule stabilizing agents. A phase I/II and pharmacokinetic trial of ixabepilone was conducted in patients with recurrent high-grade gliomas. Adult patients received ixabepilone as a 1-h infusion daily for 5 days every 3 weeks. A modified continual reassessment method was used to escalate doses, beginning at 5.0 mg/m(2), in patients stratified by use or non-use of enzyme inducing antiepileptic drugs (EIAED). In the phase I study, the maximum tolerated dose (MTD) and pharmacokinetics of ixabepilone were determined for each group. The phase II study used a two-stage design to evaluate response rate. Secondary endpoints were survival and 6-month progression free survival. In the phase I trial, 38 patients (median age 54 years) were enrolled. The MTD was 6.8 mg/m(2) for patients not taking EIAEDs and 9.6 mg/m(2) for those taking EIAEDs. The dose limiting toxicities in both groups were hematologic. Twenty-three patients (median age 54 years) were enrolled in the first stage of the phase II trial. No objective responses were observed. Median overall survival was 5.8 (95% CI, 5.0-8.6) months and 6-month PFS rate was 4% (95% CI, 0-22%). The overall mean total body clearance for ixabepilone was significantly higher (P = 0.003) in patients receiving EIAEDs (36 ± 11 l/h/m(2)) than those not (24 ± 9.2 l/h/m(2)). Patients on EIAEDs had a substantially higher MTD likely due to induction of cytochrome P450. Ixabepilone had no activity in patients with recurrent high-grade gliomas.

Phase II preradiation R115777 (tipifarnib) in newly diagnosed GBM with residual enhancing disease.

Glioblastoma multiforme (GBM) is a lethal primary malignant brain tumor in adults. R115777 (tipifarnib) is an oral agent with antiproliferative effects, being a potent and selective inhibitor of farnesyltransferase. This multicenter, open-label phase II study was designed to evaluate the efficacy and safety of R115777 given after surgery and prior to radiation in patients with newly diagnosed and residual enhancing GBM. Following surgery, an MRI confirmed the presence of residual enhancing tumor. Patients on enzyme-inducing antiseizure drugs (EIASDs) received 600 mg twice per day, and those not on EIASDs received 300 mg twice per day. One to three monthly cycles of R115777 were administered, and radiation was initiated with progression or after three cycles. A cycle consisted of 3 weeks of continuous R115777 followed by a 1-week rest. MRI was done monthly. The primary end point was overall survival; secondary end points were tumor response rate and toxicity. A total of 28 confirmed GBM patients entered the study; 15 patients (54%) were on EIASDs. The overall median time of survival was 7.7 months. There were no tumor responses. Eight patients (29%) had stable disease as the best response. The study was stopped early due to progression of the disease in 12 patients (48%). A total of 24 patients (85%) were off study before the planned treatment schedule for radiation therapy. R115777 administered prior to radiation therapy in patients with newly diagnosed GBM and residual enhancing disease did not result in any measurable responses or improvement in survival. R115777 administered prior to radiation therapy is not recommended for patients with newly diagnosed GBM.

Phase I safety study of escalating doses of atrasentan in adults with recurrent malignant glioma.

Atrasentan is an oral selective endothelin-A receptor antagonist that may inhibit cell proliferation and interfere with angiogenesis during glioma growth. We conducted a dose-finding study to assess atrasentan's safety and toxicity and to gather preliminary evidence of efficacy. Patients with recurrent malignant glioma received oral atrasentan at >or=10 mg/day. We increased the dose among cohorts until the maximum tolerated dose (MTD) was defined. Patients were evaluated for response every 8 weeks and remained on the study until the tumor progressed or toxicities occurred. Twenty-five patients were enrolled, with a median age of 53 years (range, 25-70) and a median KPS of 90% (range, 60-100%). Twenty-two patients had glioblastoma multiforme (GBM), 2 had anaplastic astrocytoma, and 1 had an anaplastic oliogodendroglioma; 24 patients had received one prior chemo therapy regimen before being enrolled in the study. The most common atrasentan-related toxicities were grade 1 or 2 rhinitis, fatigue, and edema. One patient developed grade 3 hypoxia and peripheral edema at a dose of 90 mg/day. We observed no dose-limiting toxicities in an expanded cohort of 10 patients at 70 mg/day, which was declared the MTD. Two partial responses (8%) were seen in patients with GBM at the 70- and 90-mg/day dose levels, and 4 patients had stable disease before progressing. Nineteen patients have died, and median survival was 6.0 months (95% confidence interval, 4.2-9.5 months). We conclude that the MTD of daily oral atrasentan in patients with recurrent malignant glioma is 70 mg/day. Further study of atrasentan with radiation therapy and temozolomide in newly diagnosed GBM is warranted to evaluate the efficacy of this novel agent.

The effect of enzyme-inducing antiseizure drugs on the pharmacokinetics and tolerability of procarbazine hydrochloride.

PURPOSE: Procarbazine hydrochloride (PCB) is one of the few anticancer drugs with activity against high-grade gliomas. This study was conducted to determine if the maximum tolerated dose and pharmacokinetics of PCB are affected by the concurrent use of enzyme-inducing antiseizure drugs (EIASD). EXPERIMENTAL DESIGN: Adults with recurrent high-grade glioma were divided into cohorts who were (+) and were not (-) taking EIASDs. PCB was given orally for 5 consecutive days each month. Six patients were evaluated at each dose level beginning with 200 mg/m2/d and escalated using the modified continual reassessment method. Toxicity and response were assessed. Pharmacokinetic studies were done with a new electrospray ionization mass spectrometry assay. RESULTS: Forty-nine patients were evaluated. The maximum tolerated dose was 393 mg/m2/d for the +EIASD group and the highest dose evaluated in -EIASD patients was 334 mg/m2/d. Myelosuppression was the primary dose-limiting toxicity. Significant hepatic dysfunction occurred in three patients in the +EIASD cohort. Four partial responses (8%) and no complete responses were observed. PCB exhibited linear pharmacokinetics with no significant differences between the two cohorts. A marked increase in peak PCB levels was noted on day 5 relative to day 1, which was not attributable to drug accumulation. CONCLUSIONS: This study suggests that (a) EIASD use does not significantly affect the pharmacokinetics of PCB; (b) changes in the peak plasma concentration of PCB, consistent with decreased apparent oral clearance due to autoinhibition of hepatic metabolism, occur with daily dosing; and (c) severe hepatic dysfunction may accompany this administration schedule.

Repeatability of 18F-FLT PET in a Multicenter Study of Patients with High-Grade Glioma.

Quantitative 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET has potential as a noninvasive tumor biomarker for the objective assessment of response to treatment. To guide interpretation of these quantitative data, we evaluated the repeatability of 18F-FLT PET as part of a multicenter trial involving patients with high-grade glioma. Methods:18F-FLT PET was performed on 10 patients with recurrent high-grade glioma at 5 different institutions within the Adult Brain Tumor Consortium trial ABTC1101. Data were acquired according to a double baseline protocol in which PET examinations were repeated within 2 d of each other with no intervening treatment. On each of the 2 imaging days, dedicated brain PET was performed at 2 time points, 1 and 3 h after 18F-FLT administration. Tumor SUVs and related parameters were measured at a central laboratory using various volumes of interest: isocontour at 30% of the maximum pixel (SUVmean_30%), gradient-based segmentation (SUVmean_gradient), the maximum pixel (SUVmax), and a 1-mL sphere at the region of highest uptake (SUVpeak). Repeatability coefficients (RCs) were calculated from the relative differences between corresponding SUV measurements obtained on the 2 d. Results: RCs for tumor SUVs were 22.5% (SUVmean_30%), 23.8% (SUVmean_gradient), 23.2% (SUVmax), and 18.5% (SUVpeak) at 1 h after injection. Corresponding data at 3 h were 22.4%, 25.0%, 27.3%, and 23.6%. Normalizing the tumor SUV data with reference to a background region improved repeatability, and the most stable parameter was the tumor-to-background ratio derived using SUVpeak (RC, 16.5%). Conclusion: SUV quantification of 18F-FLT uptake in glioma had an RC in the range of 18%-24% when imaging began 1 h after 18F-FLT administration. The volume-of-interest methodology had a small but not negligible influence on repeatability, with the best performance obtained using SUVpeak Although changes in 18F-FLT SUV after treatment cannot be directly interpreted as a change in tumor proliferation, we have established ranges beyond which SUV differences are likely due to legitimate biologic effects.

Timed sequential therapy of the selective T-type calcium channel blocker mibefradil and temozolomide in patients with recurrent high-grade gliomas.

Background: Mibefradil (MIB), previously approved for treatment of hypertension, is a selective T-type calcium channel blocker with preclinical activity in high-grade gliomas (HGGs). To exploit its presumed mechanism of impacting cell cycle activity (G1 arrest), we designed a phase I study to determine safety and the maximum tolerated dose (MTD) of MIB when given sequentially with temozolomide (TMZ) in recurrent (r)HGG. Methods: Adult patients with rHGG ≥3 months from TMZ for initial therapy received MIB in 4 daily doses (q.i.d.) for 7 days followed by standard TMZ at 150-200 mg/m2 for 5 days per 28-day cycle. MIB dose escalation followed a modified 3 + 3 design, with an extension cohort of 10 patients at MTD who underwent 3'-deoxy-3'-18F-fluorothymidine (18F-FLT) PET imaging, to image proliferation before and after 7 days of MIB. Results: Twenty-seven patients were enrolled (20 World Health Organization grade IV, 7 grade III; median age 50 y; median KPS 90). The MTD of MIB was 87.5 mg p.o. q.i.d. Dose-limiting toxicities were elevation of alanine aminotransferase/aspartate aminotransferase (grade 3) and sinus bradycardia. The steady-state maximum plasma concentration of MIB at the MTD was 1693 ± 287 ng/mL (mean ± SD). 18F-FLT PET imaging showed a significant decline in standardized uptake value (SUV) signal in 2 of 10 patients after 7 days of treatment with MIB. Conclusions: MIB followed by TMZ was well tolerated in rHGG patients at the MTD. The lack of toxicity and presence of some responses in this selected patient population suggest that this regimen warrants further investigation.

Dose escalation of carmustine in surgically implanted polymers in patients with recurrent malignant glioma: a New Approaches to Brain Tumor Therapy CNS Consortium trial.

PURPOSE: This New Approaches to Brain Tumor Therapy CNS Consortium study sought to determine the maximum-tolerated dose (MTD) of carmustine (BCNU) that can be implanted in biodegradable polymers following resection of recurrent high-grade gliomas and the systemic BCNU exposure with increasing doses of interstitial BCNU. PATIENTS AND METHODS: Forty-four adults underwent tumor debulking and polymer placement. Six patients per dose level were studied using polymers with 6.5%, 10%, 14.5%, 20%, and 28% BCNU by weight. Toxicities were assessed 1 month after implantation by a safety monitoring committee to determine whether subsequent escalations should occur. Nine additional patients were studied at the MTD to confirm safety. BCNU blood levels were obtained before and after polymer implantation. RESULTS: No dose-limiting toxicities were identified at the 6.5%, 10%, or 14.5% dose levels, although difficulties with wound healing, seizures, and brain edema were noted. At the 20% dose, these effects seemed more prominent, and six additional patients were treated at this dose and tolerated treatment well. Three of four patients receiving the 28% polymers developed severe brain edema and seizures, and accrual to this cohort was stopped. Nine additional patients received 20% polymer, confirming this as the MTD. Maximum BCNU plasma concentrations with the 20% loaded polymers were 27 ng/mL. Overall median survival was 251 days. CONCLUSION: The MTD of BCNU delivered in polymer to the surgical cavity is 20%. This polymer provides five times more BCNU than standard commercially available BCNU polymers and results in minimal systemic BCNU exposure. Additional studies are needed to establish the efficacy of high-dose BCNU polymers.

Phase 2 trial of copper depletion and penicillamine as antiangiogenesis therapy of glioblastoma.

Penicillamine is an oral agent used to treat intracerebral copper overload in Wilson's disease. Copper is a known regulator of angiogenesis; copper reduction inhibits experimental glioma growth and invasiveness. This study examined the feasibility, safety, and efficacy of creating a copper deficiency in human glioblastoma multiforme. Forty eligible patients with newly diagnosed glioblastoma multiforme began radiation therapy (6000 cGy in 30 fractions) in conjunction with a low-copper diet and escalating doses of penicillamine. Serum copper was measured at baseline and monthly. The primary end point of this study was overall survival compared to historical controls within the NABTT CNS Consortium database. The 25 males and 15 females who were enrolled had a median age of 54 years and a median Karnofsky performance status of 90. Surgical resection was performed in 83% of these patients. Normal serum copper levels at baseline (median, 130 microg/dl; range, 50-227 microg/dl) fell to the target range of <50 microg/dl (median, 42 microg/dl; range, 12-118 microg/dl) after two months. Penicillamine-induced hypocupremia was well tolerated for months. Drug-related myelosuppression, elevated liver function tests, and skin rash rapidly reversed with copper repletion. Median survival was 11.3 months, and progression-free survival was 7.1 months. Achievement of hypocupremia did not significantly increase survival. Although serum copper was effectively reduced by diet and penicillamine, this antiangiogenesis strategy did not improve survival in patients with glioblastoma multiforme.

Oral sodium phenylbutyrate in patients with recurrent malignant gliomas: a dose escalation and pharmacologic study.

We determined the maximum tolerated dose (MTD), toxicity profile, pharmacokinetic parameters, and preliminary efficacy data of oral sodium phenylbutyrate (PB) in patients with recurrent malignant gliomas. Twenty-three patients with supratentorial recurrent malignant gliomas were enrolled on this dose escalation trial. Four dose levels of PB were studied: 9, 18, 27, and 36 g/day. Data were collected to assess toxicity, response, survival, and pharmacokinetics. All PB doses of 9, 18, and 27 g/day were well tolerated. At 36 g/day, two of four patients developed dose-limiting grade 3 fatigue and somnolence. At the MTD of 27 g/day, one of seven patients developed reversible grade 3 somnolence. Median survival from time of study entry was 5.4 months. One patient had a complete response for five years, and no partial responses were noted, which yielded an overall response rate of 5%. Plasma concentrations of 706, 818, 1225, and 1605 muM were achieved with doses of 9, 18, 27, and 36 g/day, respectively. The mean value for PB clearance in this patient population was 22 liters/h, which is significantly higher than the 16 liters/h reported in patients with other malignancies who were not receiving P450 enzyme-inducing anticonvulsant drugs (P = 0.038). This study defines the MTD and recommended phase 2 dose of PB at 27 g/day for heavily pretreated patients with recurrent gliomas. The pharmacology of PB appears to be affected by concomitant administration of P450-inducing anticonvulsants.

Phase I clinical and pharmacokinetic study of irinotecan in adults with recurrent malignant glioma.

PURPOSE: A preliminary evaluation of the efficacy of irinotecan in patients with malignant glioma demonstrated modest activity. A markedly lower than expected incidence of drug-related toxicity was also noted. This was consistent with pharmacokinetic data indicating that the total body clearance (CL) of irinotecan in this patient population was considerably greater than in colorectal cancer patients. Concomitant medications used chronically in brain cancer patients, especially glucocorticoids and anticonvulsants that induce hepatic enzymes involved in the metabolism or excretion of drugs, were believed to be the cause of the alteration in pharmacokinetic behavior. A Phase I study was therefore undertaken in patients with recurrent malignant gliomas to independently determine the maximum tolerated dose (MTD) of irinotecan in patients stratified according to the use of enzyme-inducing anticonvulsants (EIAs). EXPERIMENTAL DESIGN: Patients with recurrent malignant gliomas received irinotecan as a weekly 90-min i.v. infusion for four consecutive weeks, with additional cycles of treatment repeated every 6 weeks. The starting dose was 125 mg/m(2)/week for both groups of patients (+/-EIA). Groups of >/==" BORDER="0">3 patients were evaluated at each dose level, and the modified continual reassessment method was used for dose adjustments. The plasma pharmacokinetics of irinotecan, its active metabolite, 7-ethyl-10-hydroxy-camptothecin (SN-38), and the glucuronide conjugate of SN-38, SN-38 glucuronide, were determined in all patients during treatment with the first weekly dose. RESULTS: Forty patients were enrolled into the study and treated with a total of 135 cycles of irinotecan. The MTD was determined to be 411 mg/m(2)/week in the +EIA cohort and 117 mg/m(2)/week in the -EIA cohort for the weekly x 4 every 6 weeks schedule. Pharmacokinetic studies showed that the CL of irinotecan was distinctly dose dependent in the patients receiving EIAs, decreasing from approximately 50 liters/h/m(2) at the lower dose levels (125-238 mg/m(2)) to a mean +/- SD value of 29.7 +/- 9.0 liters/h/m(2) (n = 7) at the MTD. The grand mean CL for a group of 13 patients who were not taking EIAs, 18.8 +/- 10.6 liters/h/m(2), was significantly different from the mean CL at the MTD of the +EIA cohort (P = 0.033). Mean values of the AUC of SN-38 (P = 0.4) and SN-38 glucuronide (P = 0.55) were not significantly different at the MTDs for the two cohorts of patients. CONCLUSIONS: The MTD of irinotecan was 3.5 times greater in patients with malignant glioma who were concurrently receiving EIAs than in those who were not. This study has also served to confirm that the concomitant administration of EIAs results in marked enhancement in the CL of irinotecan. These findings have important implications for subsequent clinical trials to further evaluate irinotecan in brain cancer patients and underscore the importance of assessing the potential for pharmacokinetic interactions between concurrent medications and chemotherapeutic agents.