Temozolomide Regimen Research Articles

Recurrent High-Grade Glioma

Opinions vary on the best treatment options for recurrent high-grade glioma. Some argue that bevacizumab should become standard of care for patients with recurrent glioblastoma, especially in light of recent FDA approval for this indication. However, this opinion is not uniformly accepted. Age, performance status, histology, tumor size and location, O6-methylguanine-DNA methyltransferase (MGMT) methylation status for glioblastoma, 1p/19q status for oligodendroglial tumors, and the number and types of prior therapies are important considerations. In addition, recurrent disease must be distinguished from "pseudoprogression" due to treatment effects. Enrollment in a clinical trial is the optimal choice for most patients with recurrent high-grade glioma after failure of radiation therapy and temozolomide. For patients who are ineligible or do not have access to clinical trials, then either bevacizumab monotherapy or bevacizumab in combination with a second agent such as irinotecan is recommended. Involved-field external beam radiation should be considered for patients with anaplastic gliomas who have not received radiation. For patients with anaplastic astrocytoma who progress after radiotherapy, temozolomide may be used. For patients with anaplastic oligodendroglioma who progress after radiotherapy, PCV chemotherapy and temozolomide are options. Oligodendroglial tumors with 1p/19q deletions are more likely to respond to treatment. In the past, carmustine was commonly used to treat recurrent high-grade glioma, but the utility of carmustine in the modern era is unknown because most studies were performed prior to the widespread use of temozolomide. High-precision re-irradiation such as stereotactic radiosurgery is another option in high-grade glioma, especially for patients with poor bone marrow reserve or inability to tolerate chemotherapy, but there is a paucity of studies with adequate controls. Surgery may be useful as adjuvant treatment for patients with symptoms due to mass effect or for patients requiring definitive histopathology, but it generally should be combined with another treatment modality. Emerging therapies, including dose-intense temozolomide regimens, targeted molecular inhibitors, other antiangiogenic therapies, viral gene therapies, immunotherapies, and convection-enhanced delivery of targeted immunotoxins, are still under investigation.

Temozolomide and cisplatin combination in naive patients with metastatic cutaneous melanoma: results of a phase II multicenter trial

Temozolomide (TMZ) is a second-generation alkylating agent that has recently shown some efficacy in stage IV melanoma. The purpose of this study was to test the efficacy and safety of combination therapy with TMZ and cisplatin (CDDP) in patients with metastatic melanoma. Chemo-naive patients with metastatic cutaneous melanoma were included in a phase II study of combined therapy with TMZ (200 mg/m/day), days 1-5, and CDDP (75 mg/m/day) on day 1. The treatment was given every 28 days, for up to six cycles. The primary endpoint was the overall response rate and the secondary endpoints were progression-free survival, probability of survival, and tolerance. Thirty patients were enrolled into this study. Median age was 59 years. A total of 126 cycles were administered. Grade 3 and 4 hematological toxicity was observed in 14 patients (46.6%) and clinical toxicity in seven patients (23.3%). No complete response was observed among the 30 included patients. Five patients (16.7%) achieved a partial response. An additional six patients (20%) showed disease stabilization and 17 patients (56.6%) revealed progressive disease. Median survival and median response duration were 8 and 7.2 months, respectively. One- and 2-year survivals were 36.7 and 13.3%. One- and 2-year progression-free survivals were 13.3 and 3.3%. Our results suggest that concurrent adjunction of CDDP to TMZ regimen increases toxicity according to this schedule and does not improve the outcome of stage IV melanoma. The objective response rate is close to response rates observed with single-agent chemotherapy.

A prospective study of temozolomide plus thalidomide during and after radiation therapy for pediatric diffuse pontine gliomas: preliminary results of the Korean Society for Pediatric Neuro-Oncology study

This prospective study was performed to determine the efficacy and safety of temozolomide (TMZ) plus thalidomide during and after radiation therapy (RT) in pediatric patients with newly diagnosed diffuse pontine glioma (DPG). Seventeen patients with pediatric DPG were enrolled between November 2004 and March 2008. The median age was eight years (range, 3-16years); seven patients were male and ten were female. With the exception of one glioblastoma case, which was diagnosed via open biopsy, all diagnoses were established using neuroradiological studies. The authors used the Korean Society for Pediatric Neuro-Oncology (KSPNO)-A053 protocol. The mean follow-up period was 12months (range, 8.5-25months). Five patients were withdrawn from the study. The rates of response to treatment and survival were analyzed in 12 patients. Ten out of the 12 patients showed a partial response (PR), whereas one patient exhibited stable disease (SD) and another patient had progressive disease (PD). The tumor control rate was 92% (11/12) and the response rate was 83% (10/12). The median progression-free survival (PFS) of the 12 patients was 7.2months (95% confidence interval (CI), 3.6-10.7). Six-month and twelve-month PFS were 58.3 and 16.7%, respectively. Overall survival (OS) was 12.7months (95% CI, 10.4-15.1). One and two-year survival were 58.3 and 25%, respectively. The main adverse effect was hematological toxicity, with four patients exhibiting grade 3 or 4 toxicity. All patients tolerated the regimen well enough to continue the adjuvant chemotherapy. No Pneumocystis jiroveci pneumonia was noted. The TMZ plus thalidomide regimen was safe and tolerated well enough to be administered on an outpatient basis. Larger studies are required to demonstrate the efficacy of this regimen.

Dose-dense temozolomide regimen for the treatment of brain metastases from melanoma, breast cancer, or lung cancer not amenable to surgery or radiosurgery: a multicenter phase II study

BackgroundBrain metastases reduce survival because therapeutic options are limited. This phase II study evaluated the efficacy of single-agent therapy with alternating weekly, dose-dense temozolomide in pretreated patients with brain metastases prospectively stratified by primary tumor type. MethodsEligible patients had bidimensionally measurable brain metastases from histologically/cytologically confirmed melanoma, breast cancer (BC), or non-small-cell lung cancer (NSCLC). Prior chemotherapy, radiotherapy, and whole-brain radiotherapy (WBRT) were allowed. Patients received temozolomide 150 mg/m2/day (days 1–7 and 15–21 every 28- or 35-day cycle). ResultsIn the intent-to-treat population (N=157; 53 melanoma, 51 BC, and 53 NSCLC), one patient had complete response, nine (6%) had partial responses, and 31 (20%) had stable disease in the brain. Median progression-free survival was 56, 58, and 66 days for melanoma, BC, and NSCLC, respectively. Median overall survival was 100 days for melanoma, 172 days for NSCLC, and not evaluable in the BC group. Thrombocytopenia was the most common adverse event causing dose modification or treatment discontinuation. Grade 4 toxic effects were rare. ConclusionsThis alternating weekly, dose-dense temozolomide regimen was well tolerated and clinically active in heavily pretreated patients with brain metastases, particularly in patients with melanoma. Combining temozolomide with WBRT or other agents may improve clinical outcomes.

Temozolomide and MGMT forever?

To the outside world, it may seem that neuro-oncologists involved in the development of novel treatment approaches to gliomas are narrow-minded and very preoccupied with one drug, temozolomide (TMZ), and one enzyme, O6-methylguanylmethyltransferase (MGMT). TMZ was approved for recurrent anaplastic glioma and glioblastoma in 1997 and soon became a standard of care in this setting.1,2 In 2005, the European Organization for Research and Treatment of Cancer-National Cancer Institute of Canada trial set a new standard of care for newly diagnosed glioblastoma3 and the role of TMZ in recurrent glioblastoma became questionable because fewer and fewer patients were TMZ-naive at recurrence. In the absence of promising competitor agents, however, it soon became clinical practice to re-expose TMZ-pretreated patients to the same drug (rechallenge) when relapse occurred after a treatment-free interval. Moreover, for patients failing the standard TMZ, various competing alternative TMZ dosing regimens of temozolomide were explored based on various theoretical assumptions, including MGMT depletion in tumor cells and anti-angiogenic, metronomic chemotherapy-like effects of TMZ; such regimens included continuous daily temozolomide (see also: clinicaltrials.gov NCT00392171),4 3 weeks on/1 week off,5 and 1 week on/1 week off.6 In the present issue of Neuro-Oncology, Kong and colleagues7 report another small phase II study of continuous daily TMZ (40–50 mg/m2) in patients with recurrent glioblastoma. Their progression-free survival rate at 6 months of 32.5% confirms to the point what has been reported in this setting.4,8 Because of the small patient numbers and different patterns of prior treatment, it is impossible to select the best of these schedules to carry forward, for example, for combination trials, but it can be assumed that the rate of progression-free survival at 6 months with these regimens will be in the range of 30% even in TMZ-pretreated patients. Two of these regimens are currently being studied in a non-comparative randomized phase II design (DIRECTOR, clinicaltrials.gov NCT00941460). Uniformly all studies report that the MGMT promoter methylation status determined at diagnosis does not correlate with the benefit derived from alternative TMZ regimens given at recurrence.5–7 Although many of the rationales for using alternative TMZ dosing regimens at recurrence center on overcoming MGMT-mediated resistance, surprisingly little is known regarding the MGMT status at recurrence and its prognostic or predictive significance. Also in this issue of Neuro-Oncology, Brandes and colleagues9 assessed the MGMT status in 38 paired samples of primary and recurrent glioblastomas. The MGMT status changed in 14 patients (37%), more often from methylated to unmethylated (8 of 13 patients) than from unmethylated to methylated (6 of 25 patients). Again, only the MGMT status determined at diagnosis was prognostic. While both new reports7,9 advance our understanding of the role of TMZ and MGMT status at recurrence, several questions remain. How can we be sure that pseudoprogression did not contribute to the 30% rate of stable disease at 6 months, particularly patients switched to alternative TMZ regimens during the 6 standard maintenance cycles? Which mechanisms drive changes in the MGMT status from first to recurrent tumor and how reliable are such assessments, and is MGMT status within the recurrent tumor as homogeneous as it presumably is in primary tumors? Answers to these questions are clinically relevant and will shape the standards of care in the diagnosis and treatment of glioblastoma for years, justifying our current apparent preoccupation with temozolomide and MGMT.10

Short-term Radiotherapy followed by Adjuvant Chemotherapy in Poor-Prognosis Patients with Glioblastoma

The optimal treatment for patients with glioblastoma with unfavorable prognostic factors, such as old age and low performance status, remains controversial. We conducted a prospective study to assess the effect of temozolomide and short-course radiation versus short-course radiation alone in the treatment of poor-prognosis patients with newly diagnosed glioblastoma. Forty-five patients with a newly diagnosed glioblastoma, older than 70 years or aged 50-70 years and with a Karnofsky performance score <or=70 were enrolled in this prospective study. Twenty-three patients were treated with an abbreviated course of radiotherapy (30 Gy in 6 fractions over 2 weeks) and 22 patients with the same radiotherapy schedule plus adjuvant temozolomide at the dose of 150-200 mg/m(2) for 5 days every 28-day cycle. The primary end point was overall survival. Secondary end points included progression-free survival and toxicity. Median overall survival was 7.3 months in the radiotherapy group and 9.4 months in the radiotherapy plus temozolomide group (P = 0.003), with respective 6-month overall survivals of 78% and 95%, respectively. Median progression-free survival was 4.4 months in the radiotherapy group and 5.5 months in the radiotherapy plus temozolomide group (P = 0.01), and respective 6-month progression-free survival rates were 22% and 45%. In multivariate analysis, Karnofsky performance score was the only significant independent predictive factor of survival (P = 0.03). Adverse effects of radiotherapy were mainly represented by neurotoxicity (24%), which resolved in most cases with the use of steroids. Grade 3-4 hematologic toxicity occurred in 36% of patients treated with temozolomide. The addition of temozolomide to short-term radiotherapy resulted in a statistically significant survival benefit with minimal additional toxicity in poor-prognosis patients with newly diagnosed glioblastoma. Future studies need to define the best combined regimens of radiotherapy and temozolomide on survival and quality of life in this subgroup of patients.

Treatment of recurrent high-grade gliomas

Although therapies for patients with recurrent high-grade gliomas are limited, there has been important progress recently. This review summarizes current treatments for recurrent high-grade gliomas with an emphasis on more novel approaches. There is increasing evidence that antiangiogenic therapies have activity in high-grade gliomas. Recently, the United States Food and Drug Administration granted accelerated approval of bevacizumab, a humanized monoclonal antibody against vascular endothelial growth factor, for the treatment of recurrent glioblastomas. Bevacizumab decreases corticosteroid requirements and improves radiologic response rates and progression-free survival. The extent to which these agents prolong overall survival remains to be determined. There is also emerging evidence that other therapies such as dose-dense and metronomic temozolomide regimens, targeted molecular agents, and other antiangiogenic therapies may have activity in recurrent high-grade gliomas. Although there has been progress in treating recurrent high-grade gliomas, the prognosis remains poor and much work still needs to be done to improve on the current results of antiangiogenic and targeted molecular therapies, as well as other novel therapies.

Chemoradiotherapy of Newly Diagnosed Glioblastoma With Intensified Temozolomide

To evaluate the toxicity and efficacy of chemoradiotherapy with temozolomide (TMZ) administered in an intensified 1-week on/1-week off schedule plus indomethacin in patients with newly diagnosed glioblastoma. A total of 41 adult patients (median Karnofsky performance status, 90%; median age, 56 years) were treated with preirradiation TMZ at 150 mg/m(2) (1 week on/1 week off), involved-field radiotherapy combined with concomitant low-dose TMZ (50 mg/m(2)), maintenance TMZ starting at 150 mg/m(2) using a 1-week on/1-week off schedule, plus maintenance indomethacin (25 mg twice daily). The median follow-up interval was 21.7 months. Grade 4 hematologic toxicity was observed in 15 patients (36.6%). Treatment-related nonhematologic Grade 4-5 toxicity was reported for 2 patients (4.9%). The median progression-free survival was 7.6 months (95% confidence interval, 6.2-10.4). The 1-year survival rate was 73.2% (95% confidence interval, 56.8-84.2%). The presence of O(6)-methylguanine-DNA methyltransferase (MGMT) gene promoter methylation in the tumor tissue was associated with significantly superior progression-free survival. The dose-dense regimen of TMZ administered in a 1-week on/1-week off schedule resulted in acceptable nonhematologic toxicity. Compared with data from the European Organization for Research and Treatment of Cancer/National Cancer Institute of Canada trial 26981-22981/CE.3, patients with an unmethylated MGMT gene promoter appeared not to benefit from intensifying the TMZ schedule regarding the median progression-free survival and overall survival. In contrast, data are promising for patients with a methylated MGMT promoter.

Phase I trial of temozolomide plus O6-benzylguanine 5-day regimen with recurrent malignant glioma

This phase I clinical trial conducted with patients who had recurrent or progressive malignant glioma (MG) was designed to determine the maximum tolerated dose (MTD) and toxicity of three different 5-day dosing regimens of temozolomide (TMZ) in combination with O(6)-benzylguanine (O(6)-BG). Both TMZ and O(6)-BG were administered on days 1-5 of a 28-day treatment cycle. A bolus infusion of O(6)-BG was administered at 120 mg/m(2) over 1 h on days 1, 3, and 5, along with a continuous infusion of O(6)-BG at 30 mg/m(2)/day. TMZ was administered at the end of the first bolus infusion of O(6)-BG and then every 24 h for 5 days during the continuous infusion of O(6)-BG. Patients were accrued to one of three 5-day dosing regimens of TMZ. Twenty-nine patients were enrolled into this study. The dose-limiting toxicities (DLTs) were grade 4 neutropenia, leukopenia, and thrombocytopenia. The MTD for TMZ for the three different 5-day dosing schedules was determined as follows: schedule 1, 200 mg/m(2) on day 1 and 50 mg/m(2)/day on days 2-5; schedule 2, 50 mg/m(2)/day on days 1-5; and schedule 3, 50 mg/m(2)/day on days 1-5 while receiving pegfilgrastim. Thus, the 5-day TMZ dosing schedule that maximized the total dose of TMZ when combined with O(6)-BG was schedule 1. This study provides the foundation for a phase II trial of O(6)-BG in combination with a 5-day dosing schedule of TMZ in TMZ-resistant MG.

Two phase II trials of temozolomide with interferon-α2b (pegylated and non-pegylated) in patients with recurrent glioblastoma multiforme

Background:Because of the poor outcomes for patients with recurrent glioblastoma multiforme (GBM), and some laboratory and clinical evidence of efficacy using interferon in GBM, we assessed the toxicity and efficacy of temozolomide (TMZ) combined with either short-acting (IFN) or long-acting (pegylated) interferon α2b (PEG) in two single-arm phase II studies, and compared the results to 6-month progression-free survival (PFS-6) data from historical controls.Methods:Two single-arm phase II studies were carried out in adults with GBM. Patients were treated with the standard regimen of TMZ (150–200 mg m−2 per day × 5 days every month) combined with either 4 million units per m2 subcutaneously (SQ) three times weekly of IFN or 0.5 μg kg−1 SQ weekly of PEG. Physical exams and imaging evaluations were carried out every 8 weeks.Results:On the IFN study, 34 adults (74% men) were enrolled, and 29 adults (55% men) on the PEG study; median Karnofsky performance status was 80 and 90 for the IFN and PEG studies, respectively. Grade 3 or 4 toxicities were common, leucopoenia and thrombocytopoenia occurring in 35–38% and 18–21% of patients, respectively. Grade 3 or 4 fatigue occurred in 18% of patients on both studies. Lymphopoenia was infrequent. PFS-6 was 31% for 29 evaluable patients in the IFN study and 38% for 26 evaluable patients in the PEG study.Conclusion:In recurrent GBM patients, both studies of standard dose TMZ with either IFN or PEG showed improved efficacy when compared to historical controls, or reports using TMZ alone. Even though the TMZ+PEG study met criteria for further study, the results of both of these studies must be considered in light of the standard of care (TMZ plus radiotherapy) for newly diagnosed GBM, which has evolved since the inception of these studies. Despite the results of the current studies being eclipsed by the new GBM standard of care, these results can still inform the development of newer approaches for GBM, either in an earlier, upfront setting, or by extrapolation of the results and consideration of the use of PEG or IFN in conjunction with other antiglioma strategies.

Randomized Phase II Trial of Chemoradiotherapy Followed by Either Dose-Dense or Metronomic Temozolomide for Newly Diagnosed Glioblastoma

Alternative dosing schedules of temozolomide may improve survival in patients with newly diagnosed glioblastoma (GBM) by increasing the therapeutic index, overcoming common mechanisms of temozolomide resistance, or both. The goal of this randomized phase II study was to evaluate two different temozolomide regimens in the adjuvant treatment of newly diagnosed GBM. Adult patients with newly diagnosed GBM were randomly assigned to receive standard radiotherapy with concurrent daily temozolomide followed by six adjuvant cycles of either dose-dense (150 mg/m(2) days 1 to 7 and 15 to 21) or metronomic (50 mg/m(2) continuous daily) temozolomide. Maintenance doses of 13-cis-retinoic acid were then administered until tumor progression. The primary end point was overall survival (OS) at 1 year. Tumor tissue was assayed to determine O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. Eighty-five eligible patients were enrolled; 42 were randomly assigned to dose-dense and 43 to metronomic temozolomide. The 1-year survival rate was 80% for the dose-dense arm and 69% for the metronomic arm; median OS was 17.1 months (95% CI, 14.0 to 28.1 months) and 15.1 months (95% CI, 12.3 to 18.9 months), respectively. The most common toxicities were myelosuppression (leukopenia, neutropenia, and thrombocytopenia) and elevated liver enzymes. Pseudoprogression was observed in 37% of assessable patients and may have had an impact on estimates of progression-free survival (6.6 months in the dose-dense arm and 5.0 months in the metronomic arm). Both dose-dense and metronomic temozolomide regimens were well tolerated with modest toxicity. The dose-dense regimen appears promising, with 1-year survival of 80%.

Differential effect of sunitinib on the distribution of temozolomide in an orthotopic glioma model

Normalization of tumor vasculature by antiangiogenic agents may improve the delivery of cytotoxic drugs to the tumor, leading to more effective therapy. In this study, we used pharmacokinetic and pharmacodynamic approaches to investigate how sunitinib at different dose levels affects brain distribution of temozolomide (TMZ), and to ascertain the relationship between intratumoral TMZ concentrations and tumor vascularity in an orthotopic human glioma model. Three groups of intracerebral U87MG tumor-bearing mice were given either vehicle or sunitinib at 20 mg/kg or 60 mg/kg per day for 7 days before receiving a steady-state regimen of TMZ that consisted of an intravenous bolus and a 3-h intraarterial infusion. TMZ concentrations in plasma, normal brain, and brain tumor were determined, and several biomarkers related to the antiangiogenic activity of sunitinib were examined. TMZ distribution in the normal brain as indicated by the brain-to-plasma steady-state TMZ concentration ratios was analogous across the three treatment groups. The brain tumor-to-plasma steady-state TMZ concentration (ss C(t)/C(p)) ratio was significantly increased in the 20 mg/kg sunitinib group (0.98 +/- 0.17) compared with the control (0.76 +/- 0.17) and 60 mg/kg sunitinib (0.68 +/- 0.09) groups. The ss C(t)/C(p) ratios were significantly correlated with the vascular normalization index (VNI), derived from the expression of CD31, collagen IV, and alpha-smooth muscle actin, which represents the fraction of functioning vessels out of the total tumor vessels. In conclusion, the effect of sunitinib on the brain tumor distribution of TMZ was dose dependent and indicated that optimal tumor exposure was achieved at a lower dose and was associated with the VNI.

Induction of MGMT expression is associated with temozolomide resistance in glioblastoma xenografts

Temozolomide (TMZ)-based therapy is the standard of care for patients with glioblastoma multiforme (GBM), and resistance to this drug in GBM is modulated by the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Expression of MGMT is silenced by promoter methylation in approximately half of GBM tumors, and clinical studies have shown that elevated MGMT protein levels or lack of MGMT promoter methylation is associated with TMZ resistance in some, but not all, GBM tumors. In this study, the relationship between MGMT protein expression and tumor response to TMZ was evaluated in four GBM xenograft lines that had been established from patient specimens and maintained by serial subcutaneous passaging in nude mice. Three MGMT unmethylated tumors displayed elevated basal MGMT protein expression, but only two of these were resistant to TMZ therapy (tumors GBM43 and GBM44), while the other (GBM14) displayed a level of TMZ sensitivity that was similar in extent to that seen in a single MGMT hypermethylated line (GBM12). In tissue culture and animal studies, TMZ treatment resulted in robust and prolonged induction of MGMT expression in the resistant GBM43 and GBM44 xenograft lines, while MGMT induction was blunted and abbreviated in GBM14. Consistent with a functional significance of MGMT induction, treatment of GBM43 with a protracted low-dose TMZ regimen was significantly less effective than a shorter high-dose regimen, while survival for GBM14 was improved with the protracted dosing regimen. In conclusion, MGMT expression is dynamically regulated in some MGMT nonmethylated tumors, and in these tumors, protracted dosing regimens may not be effective.

Phase II trial of bevacizumab in combination with temozolomide and regional radiation therapy for up-front treatment of patients with newly diagnosed glioblastoma multiforme

2000 Background: Bevacizumab (BV) is a humanized monoclonal antibody directed against the vascular endothelial growth factor (VEGF). Based on the promising activity of BV in the treatment of recurrent glioblastoma, we are conducting a phase II trial to determine whether up-front treatment of newly diagnosed GBM with BV may be more advantageous than withholding BV until recurrence. In this trial, we evaluate the safety and efficacy of BV combined with standard of care radiation (RT) and temozolomide (TMZ) and radiation (RT) for newly-diagnosed GBM. Methods: This is a phase II trial with a 10-patient pilot and 60-patient expansion phases. Newly-diagnosed GBM patients with no prior treatments are eligible. Primary outcome measure is overall survival; the secondary outcome measure is TTP and 12-month survival. Therapy began between 3–5 weeks of surgery with BV (10 mg/kg every 2 weeks), TMZ (75 mg/m2 daily), and external beam RT (30 x 200 Gy) on the same day. After completion of radiation, patients are then placed on a maintenance phase of BV (10mg/kg every 2 weeks) and TMZ (150–200 mg/m2 5 out of every 28 days) until progression or 24 months in which patients are then maintained on BV only. Results: 70 of 70 projected GBM patients have been enrolled between August 2006 and November 2008 at UCLA and Kaiser Permanente (KP) (Northern and Southern California). All patients had resections to ensure that frozen tissue (&gt;200mg) was collected. The median age was 57.4 years (range 31–75). MGMT methylation analysis has been performed on 52/70 patients with ∼40% showing methylation. Severe adverse events to date have included ischemic stroke, pulmonary embolus, wound breakdown, GI bleeding/perforation, and renal dysfunction. Isolated cases of retinal detachment and optic neuropathy have also been observed. As of now, 35/70 patients are off study (26 due to progression and 9 due to SAE). Preliminary TTP by Kaplan-Meier analysis is promising compared to that of a UCLA/KP control group of patients that received the conventional RT/TMZ regimen. Conclusions: Addition of BV to the standard regimen of TMZ and RT for newly-diagnosed GBM is well-tolerated and shows promising efficacy. More detailed analysis of safety and efficacy will presented. [Table: see text]

Phase 1 study of LY317615 (enzastaurin) and temozolomide in patients with gliomas - EORTC trial 26054

e13005 Background: Enzastaurin (Enz) is a small selective inhibitor of protein kinase C (PKC). Synergy with temozolomide (TMZ) has been demonstrated in vitro. This phase I trial investigated optimal dosing and toxicity when Enz was combined with a standard TMZ regimen. Methods: Patients (pts) with recurrent high-grade glioma or newly diagnosed disease not amenable to radiotherapy (RT) and WHO PS 0–1 were eligible. Pts on EIAEDs were excluded. Two dose levels (DL) of Enz were explored. DL1: Loading dose 500 mg followed by 250 mg daily. DL2: Loading dose 1,125 mg followed by 500 mg daily. TMZ was given at 150 mg/m2 d1-d5 every 28 days in cycle 1, escalating to 200 mg/m2 in subsequent cycles. Dose-limiting toxicity (DLT) was defined by CTCAE 3.0 criteria in the first two cycles as (1) any non haematological toxicity grade 3/4 (2) ANC &lt; 500/mm3 (3) thrombocytopenia grade 3/4 (4) any toxicity reducing drug dose intensity to &lt;80%. Results: 15 pts were included, three at DL1, 12 at DL2. 13 pts had received prior RT, seven prior chemotherapy, and two were newly diagnosed. Median number of cycles was four (range 2–8).Treatment is ongoing in five pts. TMZ dose was escalated in all pts with no DLT. Modest and reversible thrombocytopenia was the most frequent toxicity, occurring in seven pts (3 @ Gd 1, 3 @ Gd2, 1 @ Gd 3) and led to TMZ dose reduction in two pts and treatment delays in four pts (multiple in 2). One pt discontinued after three cycles due to persistent thrombocytopenia. Five pts developed neutropenia not requiring dose modification. Two pts developed hyperbilirubinemia. Six SAE's (3 at each DL) were recorded, and one death (DL2). None was considered treatment related. Two pts showed a partial response, six pts stable disease. Conclusions: Enz can be safely combined with standard TMZ regimen. Results of the just completed phase I part with Enz 250 mg twice daily dosing will also be presented at the meeting. [Table: see text]

Efficacy of protracted dose-dense temozolomide (TMZ) in patients with progressive high-grade glioma

e13018 Background: The study was aimed to evaluate the efficacy of TMZ on a protracted dose-dense schedule after standard 5-day TMZ regimen in patients with progressive high-grade glioma. Methods: In this phase II prospective study, patients who had progression on standard 5-day TMZ for recurrence (group 1) or recurrence after concurrent radiotherapy+TMZ and ≥ 2 cycles of adjuvant TMZ (group 2) for high-grade glioma received TMZ 100 mg/m2× 21 q28 days until progression according to MacDonald's criteria. Patients were included in the study after ethical committee approval and written informed consent. The primary end-point was 6 months PFS. Secondary end-points were OS and toxicity. Results: Between October 2006 and October 2008, 25 patients were included in the study. Nine of the patients were group 1 and 16 of them were group 2. Male/female ratio was 18/7. The median age was 50 (range, 18–70) and median KPS score was 80 (range, 50–100). The histopathology was glioblastoma in 18 and grade 3 glioma (anaplastic astrocytoma, anaplastic oligoastrocytoma or anaplastic oligodendroglioma) in 7. The median cycles of 5-day TMZ received before study entry was 6 (range, 2–18) in group 1 and 6 (2–7) in group 2. With a median follow up of 6 months (1–14 months) the median number of 21-day TMZ cycles received was 2 (range, 1–8). Radiological evaluation could not be performed in 5 patients because of early clinical progression. The best response during treatment was partial response in 2 (8%), stable disease in 9 (36%), and progression in 9 (36%) out of 20 patients assessed. The median time to progression was 2 months (1–8 months) and 6 months PFS rate was 11%. The median OS time was 8 months and 1 year OS rate was 38%. Out of 80 cycles received there was no anemia; 5 (6%) grade 1, 8 (10%) grade 2, 2 (3%) grade 3 leucopenia; 1 (1%) grade 1, 2 (3%) grade 2, 1 (1%) grade 3, 1 (1%) grade 4 thrombocytopenia; 9 (11%) grade 1, 7 (9%) grade 2, 32 (40%) grade 3, and 11 (14%) grade 4 lymphopenia. Study was terminated in 2 patients (one with grade 4 thrombocytopenia and the other with grade 4 hepatic toxicity). There was no dose reduction in the study drug due to toxicity. Conclusions: Protracted dose-dense TMZ after 5-day schedule for recurrent or progressive disease has modest efficacy with tolerable toxicity. No significant financial relationships to disclose.

Rechallenge with temozolomide in patients with recurrent gliomas

Temozolomide (TMZ) is the standard of care for patients with newly diagnosed glioblastoma (GBM) as well as those with recurrent anaplastic glioma (AG) and GBM. It has become common practice to re-expose patients to TMZ who had been previously treated with TMZ, or to switch patients to alternative dosing regimens of TMZ when there are signs of relapse or progress on standard TMZ therapeutic regimens. To date, however, there is a scarcity of data on the efficacy of this therapeutic strategy, currently referred to as TMZ rechallenge. We have conducted a retrospective review of patients with recurrent glioma rechallenged with TMZ. Patients experiencing progressive disease (PD) during TMZ therapy who were rechallenged with alternative TMZ regimens and patients rechallenged after stable disease in a TMZ-free interval were evaluated separately. A total of 90 rechallenges were identified in 80 patients. The progression-free survival at 6 months (PFS-6) was 48% in patients with AG (12/25) and 27.7% in those with GBM (14/47). The PFS-6 was 16.7% in AG and 26.3% in GBM for patients switched during TMZ and 57.9 and 28.6% in patients rechallenged after a TMZ-free interval of at least 8 weeks. Relevant hematological toxicity (NCI-CTC grade 3-5) was observed in 22 of 90 rechallenges, and relevant non-hematological in ten of 90 rechallenges. Temozolomide was well tolerated and generated promising PFS-6 in patients who had previously failed TMZ, regardless if they progressed during TMZ treatment, or if they were rechallenged after a TMZ-free interval. These results suggest that the TMZ rechallenge strategy warrants further investigation in a prospective randomized trial.

Treg depletion with a low-dose metronomic temozolomide regimen in a rat glioma model.

CD4+CD25+ regulatory T cells (Treg), which constitute about 2-3% of CD4+ human T cells, are the main contributors to the maintenance of immune tolerance. Cancer patients, including glioblastoma patients, bear increased number of circulating and tumor infiltrating Treg that exert functional inhibition on tumor-specific T cells. Temozolomide (TMZ) is one of the most effective chemotherapeutic agents in glioblastoma (GBM). Lymphopenia is a common side effect of TMZ treatment, but to what extent the Treg compartment is affected by this chemotherapy has been poorly investigated. We therefore studied the impact of various TMZ regimens on Treg cell population in a TMZ-resistant rat model of glioma. RG2 glioma cells were implanted s.c. in Fischer rats. Twelve days after tumor implantation, TMZ was administered orally with schedules designed to mimic the TMZ regimens currently used in humans: 30 mg/kg per day for 5 days, or 10 mg/kg per day for 21 days. In addition, two metronomic regimens with low-dose TMZ (2 and 0.5 mg/kg per day for 21 days) were evaluated. Splenocytes and tumor infiltrating lymphocytes were analysed by flow cytometry using CD3, CD4, CD25, and Foxp3 mAbs. Statistical significance was determined by the Mann-Whitney U test, the Student's t test or the ANOVA test. In the spleen of tumor-bearing animals, low-dose TMZ metronomic regimens (0.5 and 2 mg/kg for 21 days) induced a significant decrease of Treg/CD4+ ratios (13 +/- 2; p < 0.01, 14 +/- 3; p < 0.05, respectively, vs. 19 +/- 5 for controls). On the contrary, high-dose TMZ regimen (10 mg/kg per day for 21 days or 30 mg/kg for 5 days) did not significantly modify the percentage of Treg/CD4+. Within tumors, treatment with the 0.5 mg/kg TMZ regimen induced a slight and nearly significant decrease in the percentage of Treg/CD4+ after a 2 to 3-week treatment (24 +/- 9 vs. 35 +/- 11; p = 0.06). Treg depletion induced by the low-dose metronomic TMZ regimen was accompanied by a decreased suppressive function of the remaining Treg cells as assessed by an in vitro functional test. Treatment with 0.5 mg/kg metronomic TMZ reduced tumor progression when compared to untreated animals but the effect did not reach statistical significance, indicating that Treg depletion alone is not sufficient to significantly impact tumor growth in our model of fully established tumor. A low-dose metronomic TMZ regimen, but not a standard TMZ regimen, reduced the number of circulating Tregs. These results can have clinical applications for immunotherapeutic approaches in GBM.

Phase II Trial of Temozolomide Plus O6-Benzylguanine in Adults With Recurrent, Temozolomide-Resistant Malignant Glioma

This phase II trial was designed to define the role of O(6)-benzylguanine (O(6)-BG) in restoring temozolomide sensitivity in patients with recurrent or progressive, temozolomide-resistant malignant glioma and to evaluate the safety of administering O(6)-BG in combination with temozolomide. Patients were accrued into two independent strata on the basis of histology: glioblastoma multiforme (GBM) and anaplastic glioma. Both temozolomide and O(6)-BG were administered on day 1 of a 28-day treatment cycle. Patients were administered a 1-hour O(6)-BG infusion at a dose of 120 mg/m(2) followed immediately by a 48-hour infusion at a dose of 30 mg/m(2)/d. Temozolomide was administered orally within 60 minutes of the end of the 1-hour O(6)-BG infusion at a dose of 472 mg/m(2). The primary end point was objective response rate. Secondary end points included progression-free survival, overall survival, and safety. Sixty-six of 67 patients who enrolled were treated with temozolomide and O(6)-BG. One of 34 patients (3%) with GBM (95% CI, 0.1% to 15%) and five of 32 assessable patients (16%) with anaplastic glioma (95% CI, 5% to 33%) were responders. The most commonly reported adverse events were grade 4 hematologic events experienced in 48% of the patients. O(6)-BG when added to a 1-day dosing regimen of temozolomide was able to restore temozolomide sensitivity in patients with temozolomide-resistant anaplastic glioma, but there seemed to be no significant restoration of temozolomide sensitivity in patients with temozolomide-resistant GBM.

New (alternative) temozolomide regimens for the treatment of glioma.

One barrier to successful treatment of malignant glioma is resistance to alkylating agents such as temozolomide. The cytotoxic activity of temozolomide and other alkylating agents is believed to manifest largely by the formation of O(6)-methylguanine DNA adducts. Consequently, the primary mechanism of resistance to temozolomide is a function of the activity of the DNA repair enzyme O(6)-methylguanine DNA methyltransferase (MGMT). Fortuitously, MGMT is inactivated after each reaction (i.e., suicide enzyme). Therefore, if the rate of DNA alkylation were to outpace the rate of MGMT protein synthesis, the enzyme could, in theory, be depleted. Several studies have shown that prolonged exposure to temozolomide can deplete MGMT activity in blood cells, a process that could potentially increase the antitumor activity of the drug. To date, however, there are limited data demonstrating the depletion of MGMT activity in tumor tissue exposed to temozolomide. A variety of dosing schedules that increase the duration of exposure and the cumulative dose of temozolomide are currently being investigated for the treatment of glioma, with the goal of improving antitumor activity and overcoming resistance. These alternative dosing regimens have been shown to deplete MGMT activity in peripheral blood mononuclear cells, but the regimen that provides the best balance between enhanced antitumor activity and acceptable hematologic toxicity has yet to be determined.