Multicentre phase II studies evaluating imatinib plus hydroxyurea in patients with progressive glioblastoma

Background:

We evaluated the efficacy of imatinib mesylate in addition to hydroxyurea in patients with recurrent glioblastoma (GBM) who were either on or not on enzyme-inducing anti-epileptic drugs (EIAEDs).

Methods:

A total of 231 patients with GBM at first recurrence from 21 institutions in 10 countries were enrolled. All patients received 500 mg of hydroxyurea twice a day. Imatinib was administered at 600 mg per day for patients not on EIAEDs and at 500 mg twice a day if on EIAEDs. The primary end point was radiographic response rate and secondary end points were safety, progression-free survival at 6 months (PFS-6), and overall survival (OS).

Results:

The radiographic response rate after centralised review was 3.4%. Progression-free survival at 6 months and median OS were 10.6% and 26.0 weeks, respectively. Outcome did not appear to differ based on EIAED status. The most common grade 3 or greater adverse events were fatigue (7%), neutropaenia (7%), and thrombocytopaenia (7%).

Conclusions:

Imatinib in addition to hydroxyurea was well tolerated among patients with recurrent GBM but did not show clinically meaningful anti-tumour activity.

Phase I trial combining SCH 66336 to temozolomide (TMZ) for patients with grade 3 or 4 malignant gliomas (MG)

e13004

Background: Ras plays a crucial role in the control of cellular proliferation and differentiation. Farnesylation is an essential step in the post-translational processing of Ras. SCH 66336 inhibits farnesyl transferase, the crucial enzyme in this process. We report a phase I trial of TMZ and SCH 66336. Methods: Eligibility included: adult patients with stable or recurrent MG (GBM, anaplastic astrocytoma [AA], anaplastic oligodendroglioma [AO]) previously treated with radiation therapy (RT) and with or without chemotherapy; interval of at least two weeks between prior RT, or four weeks between prior chemotherapy; Karnofsky ≥ 60%; and adequate hematologic, renal and liver function. Patients were divided in two strata: those receiving enzyme-inducing antiepileptic drugs (EIAED) and those not receiving EIAED. Each patient was treated with TMZ for five days every 28 days, first cycle dosed at 150 mg/m2 and subsequent cycles at 200 mg/m2. SCH 66336 was dosed orally daily and was dose escalated. Responses were assessed after two cycles (8 weeks). The primary endpoints of this study were to determine the maximum tolerated dose (MTD) of SCH 66336 when administered with TMZ, and the toxicity of this combination. Results: Thirty-six patients were enrolled (25 GBM, 6 AA, 3 AO). Fifteen patients have been accrued to the EIAED stratum at SCH 66336 doses of 125, 175, and 250 mg orally BID. Twenty-one patients have been accrued to the non-EIAED stratum at SCH 66336 doses of 75, 100, 150, and 200 mg orally BID. Dose-limiting toxicities were: deep venous thrombosis (1 grade 3); nausea and vomiting (1 grade 3); diarrhea (1 grade 3); elevated ALT (1 grade 3); elevated creatinine (1 grade 3); and fatigue (1 grade 3). Radiographic evaluation reported: 2 partial responses, 14 stable disease for at least 4 cycles, and 11 disease progression after either the first or second cycle. Sixteen patients have completed at least six cycles. One patient is still on treatment, completing cycle 12. The MTD of this combination for the EIAED stratum is 175 mg BID and the non-EIAED stratum is 150 mg BID. Conclusions: SCH 66336 in combination with TMZ is well-tolerated and shows promising response when administered to patient when stable on TMZ alone or after RT and TMZ.

No significant financial relationships to disclose.

Safety and efficacy of the addition of bevacizumab (BV) to temozolomide (TMZ) and radiation therapy (RT) followed by BV, TMZ, and irinotecan (CPT-11) for newly diagnosed glioblastoma multiforme (GBM)

2015

Background: Standard GBM treatment includes TMZ and RT, and results in a median progression-free survival and median survival of 6.9 and 15.8 months, respectively. GBM have high concentrations of vascular endothelial growth factor (VEGF), higher levels are associated with poorer prognosis. BV is a humanized antibody to VEGF with activity in recurrent GBMs. This study aims to improve the survival of newly diagnosed GBM patients by incorporating an anti-angiogenic agent with RT and TMZ, and adding a topoisomerase I inhibitor, and an anti-angiogenic agent to TMZ post-RT therapy. Methods: Patients received standard RT and TMZ at 75 mg/m2/day, with BV at 10 mg/kg every 14 days beginning a minimum of 28 days post-operatively. Following the completion of RT, patients received 6 cycles of BV, TMZ and CPT-11. Each cycle was 28 days. BV was given at a dose of 10 mg/kg on days 1 and 15, TMZ at 200 mg/m2 on days 1–5 and CPT-11 on days 1 and 15 at 125 mg/m2 for patients not on an enzyme inducing anti-epileptic drug (EIAED) and 340 mg/m2 for patients on an EIAED. The study was designed to differentiate between a 16-month survival rate of 45% and 60% with type I and II error rates of 0.05. Results: 75 patients were enrolled between 8/07 and 9/08. All the patients have completed RT; 40 patients continue to receive BV, TMZ, and CPT-11. Twenty-two patients have completed 6 cycles of BV, TMZ, and CPT-11; 17 of them had a cold PET One patient developed a CNS hemorrhage (grade 2) necessitating stopping BV. Five patients developed thrombocytopenia for which TMZ was held (grade 3, n = 1; grade 4, n = 4). There were no other ≥ grade 3 toxicities, including no wound dehiscence during RT. Twelve patients had tumor progression, and 14 stopped because of toxicity, including: 6 with fatigue; 3 with PEs; 2 with grade 4 thrombocytopenia; the patient with CNS hemorrhage, and one each with a rectal abscess and sepsis. There have been 7 deaths: 5 from tumor progression; one each from sepsis and PEs. At a median follow-up of 9 months, 81% remain alive and progression-free. Conclusions: Adding BV to TMZ and RT followed by BV, TMZ with CPT-11 is tolerable and efficacious.

No significant financial relationships to disclose.

Temozolomide (TMZ) and bevacizumab (BV) as initial treatment for unresectable or multifocal glioblastoma multiforme (GBM)

e13025

Background: GBMs are vascular tumors and inherently resistant to therapy. The prognosis for patients is poor with a median survival of 9–15 months. Patients with unresectable or multifocal GBMs have an even poorer prognosis, with a median survival of 6–8 months. Given the angiogenic phenotype of GBM, we conducted a phase II trial of upfront BV and 5-day TMZ in newly diagnosed unresectable or multifocal GBMs. Methods: Patients had histologically documented newly diagnosed GBMs that were unresectable or multifocal. Patients received up to 4 cycles of temozolomide at 200 mg/m2/d days 1–5 and BV at 10 mg/kg on days 1 and 14 in a 28 day cycle. An MRI was performed after every cycle and patients continued on therapy as long as there was no tumor progression, grade 4 non-hematologic toxicity or recurrent grade 4 hematologic toxicity after a dose reduction to 150 mg/m2/d. The primary endpoint was tumor response using the modified MacDonald criteria plus FLAIR and T2 sequences to evaluate non-enhancing tumor. Results were evaluated by two independent reviewers. Results: 41 patients were enrolled between October 2007 and September 2008 and 31 patients were analyzed after completion of cycle 2. As the best response, there were 8 (25.8%) partial responses, 19 (61.3 %) patients with stable disease, and 4(12.9 %) had disease progression. 19 of the 41 patients enrolled completed four cycles without tumor progression. The regimen was tolerable, with 3 grade 4 hematologic toxicities including neutropenia and thrombocytopenia. There were 2 grade 4 non-hematologic toxicities, including pulmonary embolism. There were two CNS hemorrhages. The median PFS was 3.6 months (2.9 months, 4.4 months) and the median OS was 4.5 months (3.7 months, 5.3 months). Conclusions: Upfront temozolomide and bevacizumab was well tolerated, but synergistic chemotherapy or growth factor inhibitors need to be added to produce meaningful clinical benefit, particularly for unresectable or multifocal GBM.

No significant financial relationships to disclose.

Phase I study of vandetanib, imatinib mesylate, and hydroxyurea for recurrent malignant glioma

e13007

Background: Malignant glioma (MG), an incurable primary CNS tumor, is characterized by frequent aberrant activation of EGFR, VEGFR, and PDGFR. This study will determine the MTD and DLT of vandetanib (V), a once-daily, oral selective inhibitor of VEGFR and EGFR when combined with imatinib mesylate (IM), an inhibitor of multiple tyrosine kinases including PDGFR and hydroxyurea (H). Methods: Adult recurrent MG patients with ≤ 3 prior recurrences, KPS ≥ 60% and adequate organ function were stratified based on concurrent enzyme-inducing anticonvulsant use (EIAC). Both strata were independently escalated using a “3+3” design. H is administered at 500 mg BID while IM is administered at 500 mg BID for patients on EIAC and 400 mg QD for those not on EIAC. V is increased by 100 mg in successive cohorts beginning at 100 mg and 200 mg for patients not on and on EIAC, respectively. Evaluations were after every other 28-day cycle. Pharmacokinetics of V and IM were obtained on days 1 and 28 of cycle 1. Results: Twenty-six patients (grade 4 MG, n = 20; grade 3 MG, n = 6) have enrolled. Only 1 DLT (reversible grade 4 transaminase elevation; dose level 1) occurred among 22 non-EIAC patients and enrollment to this stratum is planned to continue at dose level 4. The MTD of V for patients on EIAC is 200 mg/day due to 2 of 3 patients developing grade 3 thrombocytopenia at the 300 mg/day dose level. Evidence of therapeutic benefit to date includes 1 partial response and 15 patients (58%) with stable disease for at least 4 weeks, including 4 patients for ≥4 months. Conclusions: Combination of V, IM, and H is well-tolerated in recurrent MG patients. Further accrual is ongoing and an update of outcome, toxicity, and pharmacokinetic analyses will be presented.

No significant financial relationships to disclose.

Effect of daclizumab on TReg counts and EGFRvIII-specific immune responses in GBM

2034

Background: TRegs are increased in patients with GBM and constitutively express the high affinity interleukin-2 receptor (IL-2Rα). Treatment with an antibody that blocks IL-2Rα signaling functionally inactivates and eliminates TRegs without inducing autoimmune toxicity in murine models. We hypothesized that daclizumab, a commercially-available, IL-2Rα-specific antibody would function identically.Methods: A randomized phase II clinical trial assessed the effects of daclizumab in the context of the cancer vaccine, CDX-110, which is comprised of an EGFRvIII-specific peptide sequence linked to KLH. EGFRvIII is a constitutively activated and immunogenic mutation not expressed in normal tissues, but widely expressed in GBMs and other neoplasms. In patients with newly-diagnosed, EGFRvIII+ GBM, after resection and radiation/TMZ, patients received CDX-110 vaccinations biweekly x 3, then monthly until tumor progression in combination with TMZ (200 mg/m2 x 5/28 days). Half the patients were randomized to receive daclizumab (1mg/Kg x1) at the first vaccine. The others received saline in a double-blinded fashion.Results: There were no drug related SAEs. EGFRvIII-specific immune responses were generated in all patients, and all immune responses were sustained or enhanced during subsequent TMZ cycles. Preliminary analysis (n = 4) suggests that daclizumab reduces Treg (CD4+CD25+CD45RO+FOXP3+) numbers [change 82.4 ± 7.1% from baseline (p = 0.011; t-test)] without reducing overall CD8+ or CD4+ T-cell counts. Tregs decreased only 3.7 + 11.0% after vaccination in the saline treated group during the same interval. Preliminary analysis (n = 4) also suggest that daclizumab enhanced EGFRvIII-specific immune responses (p = 0.01; t-test) and enhanced the titer of cytotoxic EGFRvIII-specific IgG1 isotype antibodies compared to the saline treated group (p = 0.003; t-test) and compared to previously vaccinated patients who did not receive daclizumab (p = 0.0015; t-test). TTP and OS survival in both arms has not been reached. Conclusions: Daclizumab may reduce Treg counts in patients with GBM. TMZ and daclizumab may enhance EGFRvIII-targeted immune responses despite lymphodepletion. These combinations are currently under further investigation.

[Table: see text]

Phase II study of bevacizumab plus erlotinib for recurrent malignant gliomas

2045

Background: Bevacizumab (B), a neutralizing VEGF monoclonal antibody, has anti-glioma activity as single agent and in combination with cytotoxic therapy. Erlotinib (E), an EGFR tyrosine kinase inhibitor, may exhibit anti-tumor activity in some malignant glioma (MG) patients. B plus E was associated with clinical benefit in several solid tumors. We performed a single-arm, phase II study to evaluate the efficacy of B and E in patients with recurrent MG. Methods: The primary endpoint was 6-month progression-free survival (PFS-6). Radiographic response, pharmacokinetics and correlative biomarkers were secondary endpoints. E was orally administered daily at 200 mg/day for patients not on enzyme-inducing anticonvulsants (EIAC) and 500 mg/day for patients on EIAC. All patients received 10 mg/kg of B intravenously every two weeks. Key eligibility criteria included: age ≥ 18 years; KPS ≥ 60; > 4 weeks from prior surgery, XRT or chemotherapy. Patients with either > 3 prior progressions, requirement for therapeutic anti-coagulation or acute hemorrhage on pre-treatment imaging were excluded. Results: Fifty-six patients with recurrent MG (n = 24 for glioblastoma multiforme [GBM] and n = 32 for anaplastic gliomas [AGs]) were assessable for outcome. The PFS-6 rates were 25% for GBM and 50% for AGs. There was no survival difference between EIAC and non-EIAC groups. Rash (54% grade 1–2 and 38% grade 3) was the most common side effect. Nausea, diarrhea, and fatigue were common but mostly grade 1–2. Serious side effects were rare and included two patients with pulmonary embolism, single patients with either intestinal perforation, ischemic stroke, gastric bleeding, or nasal septal perforation. Pharmacokinetic and tissue biomarker profiles are in preparation. Conclusions: Among heavily pretreated recurrent MG patients, bevacizumab plus erlotinib is tolerated and associated with encouraging anti-tumor benefit.

No significant financial relationships to disclose.

Epidermal growth factor receptor variant III (EGFRvIII) vaccine (CDX-110) in GBM

2021

Background: Unlike conventional therapies for GBM, immunologic targeting of tumor-specific gene mutations allows precise eradication of neoplastic cells with reduced toxicity. EGFRvIII is a constitutively activated and immunogenic mutation not expressed in normal tissues, but widely expressed in GBM and other neoplasms. The cancer vaccine CDX-110 is comprised of an EGFRvIII-specific peptide sequence linked to keyhole limpet hemocyanin (KLH). Methods: A phase II multi-center trial assessed the immunogenicity and efficacy of CDX-110 in patients with newly-diagnosed, EGFRvIII+ GBM. After resection and radiation / TMZ, patients received CDX-110 vaccinations biweekly x 3, then monthly until tumor progression. Sequential cohorts received CDX-110 alone [ACTIVATE (n = 18)] or in combination with TMZ (200 mg/m2 x 5/28 days [ACT II A (n = 13)]) or (100 mg/m2 x 21/28 days [ACT II B (n=10)]). Results: Reversible systemic drug hypersensitivity reactions were seen in 1 ACTIVATE and 4 ACT II patients. Two patients had non-specific changes on MRI which were possibly due to the vaccine but which resolved. Despite grade 2 or 3 lymphopenia in all ACT II patients, EGFRvIII-specific immune responses were generated in all patients, and all immune responses were sustained or enhanced during subsequent TMZ cycles. Although ACT II B patients had more severe TMZ-induced lymphopenia, they developed greater EGFRvIII-specific immune responses (p = 0.028) when compared to ACT II A. EGFRvIII-specific IgG1 also increased in avidity with vaccination (Ka>>2x109M-1) in a randomly selected subset of 4 patients (p = 0.000068). Of the 23 recurrent tumors studied, 18 lost EGFRvIII expression (p = 0.001). There are no significant differences between ACT II A and B in estimated median TTP (18.5 vs. 14.9 months, p = 0.31) and OS (23.6 vs. 19.9 months, p = 0.75). ACTIVATE TTP (14.2 months) and OS (26.0 months) and ACT II TTP (15.2 months) and OS (23.6 months) compare favorably to a TMZ-treated, matched historical control group (TTP: 6.3 months; OS: 15.0 months). Conclusions: CDX-110 vaccination in patients with GBM appears very promising. TMZ enhances immune responses despite lymphodepletion. CDX-110 with simultaneous TMZ is under further investigation in a larger phase II trial.

[Table: see text]

A phase I study of sunitinib plus irinotecan in the treatment of patients with recurrent malignant glioma

e13024

Background: Malignant glioma (MG), an incurable primary CNS tumor, are highly angiogenic due to overexpression of VEGF/VEGFR. The current study was designed to determine the MTD and DLT of sunitinib (S), a once-daily, oral selective inhibitor of VEGFR when combined with irinotecan (I), a topoisomerase-1 inhibitor among recurrent MG patients. Methods: We employed a ‘3+3‘ dose escalation design to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of S, administered once daily for the first 28 days of each 42 day cycle, with I, administered every 2 weeks. The initial S and I doses were 25 mg/day and 75 mg/m2. Key eligibility criteria included KPS ≥ 70%, adequate organ function and no concurrent CYP3A-inducing anti-epileptics. Pharmacokinetic studies for S are obtained during cycle 1 among 6 additional patients treated at the MTD. Results: Eleven patients (grade 4 MG, n = 6; grade 3 MG, n = 5) have enrolled. No DLTs were observed in cohort 1, but 2 patients experienced hematologic DLT (grade 3 thrombocytopenia, n = 2; grade 4 neutropenia, n = 1) in cohort 2. Therefore the MTD for this regimen is 25 mg of S plus 75 mg/m2 of I. Evidence of therapeutic benefit to date includes 8 patients (73%) with stable disease including 3 who continue on therapy. Conclusions: Combination of sunitinib plus irinotecan is well tolerated in recurrent MG patients at the defined MTD dose level. Accrual to the PK dose expansion cohort continues.

No significant financial relationships to disclose.

Pilot study of dronabinol for adult patients with primary malignant gliomas

19607

Background: Chemotherapy-induced nausea and vomiting (CINV) are common adverse effects from chemotherapy. While most treatments administered in patients with primary gliomas are not highly emetogenic, up to 50% of neuro-oncology patients report CINV despite 5HT3 or steroid therapies. Adjuvant benzodiazepines frequently alter mental status. Dronabinol may provide a safe alternative option without compromise of neurological status. his study seeks to describe toxicities (TOX) associated with dronabinol administration in neuro-oncology patients. A secondary aim is to describe the impact that dronabinol has on their quality of life (QOL). Methods: This is an exploratory study of adult patients with WHO Grade III/IV primary gliomas on adjuvant chemotherapy. Power analysis determined a sample size of 34 subjects for 0.80 effect size. Enrollment is ongoing with 18/34 adult patients accrued. Patients take dronabinol 5 mg BID 24 hours prior to, during, and 48 hours after completion of oral/IV chemotherapy. Patients continue their established antiemetic regimen. Between chemotherapy doses, dronabinol is reduced to 2.5 mg daily. Intolerance of dronabinol is defined as 2 or more Grade 3 or greater non-hematologic TOX according to the CTC v.3 definition handbook. Modified Functional Living Index-Emesis (FLIE), Functional Assessment of Cancer Therapy-Brain Tumor (FACT-Br), Mini Mental Status Exam (MMSE), and CINV visual analog scales are collected at specific points for 2 cycles for TOX and QOL data. Results: Subjects are predominately male (n=10); mean age of 45.2 years. Four withdrew due to Grade 3 neurologic TOX of cognitive changes (n=3) despite decreasing dosages; Grade 3 persistent CINV (n=1) despite increasing dronabinol dosage. Increased dosages were required in 4 subjects to better manage CINV. Two required decreased doses for Grade 2 neurologic TOX. Most subjects (n=14) reported stable or improved QOL by FACT-Br and FLIE while the 4 withdrawn subjects reported worsening QOL related to TOX. Conclusions: Dronabinol is safe and effective for administration as an adjunct to standard antiemetic therapy during treatment for primary glioma. The dose may be titrated with minimal toxicities and improvement in QOL.

No significant financial relationships to disclose.

Phase II trial of imatinib mesylate and hydroxyurea for adults with recurrent/progressive low-grade glioma

2053

Background: We evaluated the combination of imatinib mesylate and hydroxyurea in recurrent/progressive low-grade gliomas (LGG) following the encouraging response of this combination demonstrated among adults with recurrent malignant glioma. Methods: Key eligibility criteria: age over 18 yrs; histologically confirmed grade II LGG that is recurrent/progressive following at least prior surgical resection; Karnofsky = 60% and adequate organ function. Imatinib plus hydroxyurea were given on a continuous oral daily schedule for 28 day cycles; imatinib was administered at 400 mg daily to patients not on CYP3A-enzyme inducing antiepileptic drugs (EIAED) while those on EIAED received 500 mg twice a day. All patients received 500 mg twice a day of hydroxyurea. Patients were evaluated every other month with physical and MRI examinations. Results: Twenty-seven patients with recurrent or progressive LGG have enrolled including 17 with astrocytoma and 10 with oligodendroglioma. Eleven (40.7%) are on EIAED. Median age was 42 years (range 24–66 years). 26% of patients had received prior therapy other than surgery (XRT, n=2; chemotherapy, n=5). The most frequent toxicities possibly related to the study regimen were fatigue (grade 2, n=5; grade 3, n=1), neutropenia (grade 2, n=1; grade 3, n=2), anemia (grade 2, n=2), rash (grade 2, n=2), nausea (grade 3, n=1), anorexia (grade 2, n=1), and AST elevation (grade 2, n=1). There were no grade 4 or 5 treatment-related toxicities. Among patients evaluable for response, 17 (85%) achieved stable disease and 3 (15%) had progression. Twenty patients continue on study having received 2–16 months of therapy. Additional accrual and follow-up is ongoing. Conclusions: Continuous daily treatment of imatinib plus hydroxyurea is well tolerated and associated with encouraging preliminary activity among adults with recurrent/progressive LGG.

[Table: see text]

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) evaluation in glioblastoma (GBM) patients treated with bevacizumab (BEV) and irinotecan (CPT-11)

2029

Background: Significant responses seen in GBM patients treated with BEV and CPT-11 generated the need to develop ways to predict clinical benefit. DCE-MRI can be used to evaluate the microvasculature within tumors. DCE-MRI uses Ktrans, a volume transfer constant of contrast agent between blood plasma and the extravascular extracellular space, to determine vascular permeability. A 50% reduction in Ktrans is clinically meaningful. We report a phase II trial to determine the correlation between vascular permeability and radiographic response in GBM patients treated with the combination. Methods: Eligibility included patients with recurrent GBM. Both agents were given every 14 days. All patients received BEV at 10 mg/kg IV. CPT-11 was dosed at 340 mg/m2 for patients on enzyme inducing antiepileptic drugs (EIAED) and 125 mg/m2 for patients not on EIAED. Radiographic responses were assessed every 6 weeks. DCE-MRIs were performed before administration of chemotherapy, one day after treatment and after the first cycle. The primary endpoint was to examine the effect of BEV and CPT-11 treatment on vascular permeability as measured by percent change from baseline in Ktrans. Results: Twenty patients were enrolled, with a median age of 49.5 years. Fifteen patients are assessable for response. Best responses include one patient with complete response, 8 with partial response (response rate=60%), six patients with stable disease, and one with disease progression. Ktrans values are available for 13 patients; data are not available for seven patients (too early: 4, technical difficulty: 3). A reduction in Ktrans by 50% was observed in 6 patients one day after treatment and in 12 patients at the end of cycle 1. Changes in Ktrans value were highly correlated with the percentage decline in tumor volume from baseline to end of cycle one (Pearson correlation = 0.82; p=0.0006). Fifteen patients are still on study. Five patients came off due to disease progression. Conclusions: The utilization of DCE-MRI to determine a reduction in vascular permeability following a combination of BEV and CPT-11 is feasible and correlates significantly with the degree of tumor volume decrease.

No significant financial relationships to disclose.

Phase I trial of imatinib mesylate, hydroxyurea and vatalanib for patients with recurrent glioblastoma multiforme (GBM)

2027

Background: Recent studies have demonstrated promising anti-glioma activity of imatinib mesylate (IM) and hydroxyurea (H). Angiogenesis is one of the hallmarks of GBM with VEGF as a key regulator. This study attempts to extend the efficacy of IM and H by adding a VEGF receptor inhibitor, vatalanib (V; PTK787/ZK22584). Methods: We employ a ‘3+3‘ dose escalation design to determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of IM and V when administered with fixed dose of H in adult recurrent GBM patients with < 3 prior recurrences, KPS = 70% and adequate organ function. Patients are stratified based on concurrent enzyme-inducing anticonvulsant (EIAC) administration, and both strata (A- not on EIAC and B- on EIAC) are independently dose-escalated. Initial dose levels for stratum A: IM - 400 mg/day; H - 500 mg bid; V- 250 mg bid and for stratum B: IM- 500 bid; H-500 mg bid; V- 500 mg bid. Patients are given only V on day 1–7 of cycle 1 and then IM+H+V daily thereafter. Only cycle 1 is 35 days with subsequent cycles of 28 days. Response is evaluated every other cycle. Pharmacokinetic (PK) studies are performed on days 7 and 35 of cycle 1. Results: Thirty-five recurrent GBM patients have enrolled. The median age is 51.5 (range 31 to 75), 66% are male, and 51% are on EIAC. One DLT (grade 3 thrombocytopenia) occurred in a stratum A patient on dose level three . For stratum B, two DLTs (grade 3 hypertension and ALT elevation) occurred in a patient on dose level two and one DLT (grade 3 fatigue) occurred in a patient on dose level three. MTDs for each stratum have not been reached and accrual is ongoing. PK results are pending. Ten partial responses (29%) have been observed and nine patients remain on study including three who have received more than 6 cycles of therapy. Conclusions: Combination of imatinib, hydroxyurea and vatalanib is safe and well-tolerated with an encouraging rate of radiographic response. Further accrual is in progress to define the MTD.

No significant financial relationships to disclose.