Phase II NCCTG trial of RT + irinotecan and adjuvant BCNU plus irinotecan for newly diagnosed GBM

Congress of neurological surgeons systematic review and evidence-based guidelines update on the role of chemotherapeutic management and antiangiogenic treatment of newly diagnosed glioblastoma in adults

QUESTION

What is the role of temozolomide in the management of adult patients (aged 65 and under) with newly diagnosed glioblastoma?

TARGET POPULATION

These recommendations apply to adult patients diagnosed with newly diagnosed glioblastoma.

RECOMMENDATION

Level I: Concurrent and post-irradiation Temozolomide (TMZ) in combination with radiotherapy and post-radiotherapy as described by Stupp et al. is recommended to improve both PFS and OS in adult patients with newly diagnosed GBM. There is no evidence that alterations in the dosing regimen have additional beneficial effect.

QUESTION

Is there benefit to adjuvant temozolomide treatment in elderly patients (> 65 years old?).

TARGET POPULATION

These recommendations apply to adult patients diagnosed with newly diagnosed glioblastoma.

RECOMMENDATION

Level III: Adjuvant TMZ treatment is suggested as a treatment option to improve PFS and OS in adult patients (over 70 years of age) with newly diagnosed GBM.

QUESTION

What is the role of local regional chemotherapy with BCNU biodegradable polymeric wafers in adult patients with newly diagnosed glioblastoma?

TARGET POPULATION

These recommendations apply to adult patients diagnosed with newly diagnosed glioblastoma.

RECOMMENDATION

Level III: There is insufficient evidence for the use of BCNU wafers following resection in patients with newly diagnosed glioblastoma who undergo the Stupp protocol after surgery. Further studies of higher quality are suggested to understand the role of BCNU wafer and other locoregional therapy in the setting of Stupp Protocol.

QUESTION

What is the role of bevacizumab in the adult patient with newly diagnosed glioblastoma?

TARGET POPULATION

These recommendations apply to adult patients diagnosed with newly diagnosed glioblastoma.

RECOMMENDATION

Level I: Bevacizumab in general is not recommended in the initial treatment of adult patients with newly diagnosed GBM. It continues to be strongly recommended that patients with newly diagnosed GBM be enrolled in properly designed clinical trials to assess the benefit of novel chemotherapeutic agents compared to standard therapy.

Human variability in isoform-specific UDP-glucuronosyltransferases: markers of acute and chronic exposure, polymorphisms and uncertainty factors

UDP-glucuronosyltransferases (UGTs) are involved in phase II conjugation reactions of xenobiotics and differences in their isoform activities result in interindividual kinetic differences of UGT probe substrates. Here, extensive literature searches were performed to identify probe substrates (14) for various UGT isoforms (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B7 and UGT2B15) and frequencies of human polymorphisms. Chemical-specific pharmacokinetic data were collected in a database to quantify interindividual differences in markers of acute (Cmax) and chronic (area under the curve, clearance) exposure. Using this database, UGT-related uncertainty factors were derived and compared to the default factor (i.e. 3.16) allowing for interindividual differences in kinetics. Overall, results show that pharmacokinetic data are predominantly available for Caucasian populations and scarce for other populations of different geographical ancestry. Furthermore, the relationships between UGT polymorphisms and pharmacokinetic parameters are rarely addressed in the included studies. The data show that UGT-related uncertainty factors were mostly below the default toxicokinetic uncertainty factor of 3.16, with the exception of five probe substrates (1-OH-midazolam, ezetimibe, raltegravir, SN38 and trifluoperazine), with three of these substrates being metabolised by the polymorphic isoform 1A1. Data gaps and future work to integrate UGT-related variability distributions with in vitro data to develop quantitative in vitro-in vivo extrapolations in chemical risk assessment are discussed.

Seizures and cancer: drug interactions of anticonvulsants with chemotherapeutic agents, tyrosine kinase inhibitors and glucocorticoids

Patients with cancer commonly experience seizures. Combined therapy with anticonvulsant drugs (AEDs) and chemotherapeutic drugs or tyrosine kinase inhibitors carries inherent risks on drug-drug interactions (DDIs). In this review, pharmacokinetic studies of AEDs with chemotherapeutic drugs, tyrosine kinase inhibitors, and glucocorticoids are discussed, including data on maximum tolerated dose, drug clearance, elimination half-life, and organ exposure. Enzyme-inducing AEDs (EIAEDs) cause about a 2-fold to 3-fold faster clearance of concurrent chemotherapeutic drugs metabolized along the same pathway, including cyclophosphamide, irinotecan, paclitaxel, and teniposide, and up to 4-fold faster clearance with the tyrosine kinase inhibitors crizotinib, dasatinib, imatinib, and lapatinib. The use of tyrosine kinase inhibitors, particularly imatinib and crizotinib, may lead to enzyme inhibition of concurrent therapy. Many of the newer generation AEDs do not induce or inhibit drug metabolism, but they can alter enzyme activity by other drugs including AEDs, chemotherapeutics and tyrosine kinase inhibitors. Glucocorticoids can both induce and undergo metabolic change. Quantitative data on changes in drug metabolism help to apply the appropriate dose regimens. Because the large individual variability in metabolic activity increases the risks for undertreatment and/or toxicity, we advocate routine plasma drug monitoring. There are insufficient data available on the effects of tyrosine kinase inhibitors on AED metabolism.

Quantification of the impact of enzyme-inducing antiepileptic drugs on irinotecan pharmacokinetics and SN-38 exposure

The population pharmacokinetic model reported here was developed using data from 2 phase 2 trials of irinotecan for treatment of malignant glioma to quantify the impact of concomitant therapy with enzyme-inducing antiepileptic drugs (EIAEDs) on irinotecan pharmacokinetics. Patients received weekly irinotecan doses of 100 to 400 mg/m(2) , and plasma samples were collected and analyzed for irinotecan and its APC, SN-38, and SN-38G metabolites. Nonlinear mixed-effects modeling was employed for population pharmacokinetic analysis. Concomitant therapy with phenytoin, phenobarbital, or carbamazepine increased the clearances of irinotecan, SN-38, and SN-38G but not APC. SN-38 clearance was 2-fold higher with concomitant EIAED use, resulting in 40% lower SN-38 exposure. Evaluation of additional covariates revealed no clinically relevant effects of sex or concomitant corticosteroid use. The population pharmacokinetic model suggests that a 1.7-fold increase in irinotecan dose may compensate for decreases in SN-38 exposure in the presence of concomitant EIAEDs. Although slightly more conservative, this dose adjustment is consistent with those recommended based on increases in the maximally tolerated dose for malignant glioma patients receiving EIAEDs and may be an appropriate starting point for further investigation when extrapolating to other cancer types or alternative regimens.

Incorporation of biomarkers in phase II studies of recurrent glioblastoma

The survival trends for glioblastoma (GBM) patients have remained largely static, reflecting a lack of improvement in the therapeutic options for patients. Less than 5 % of newly diagnosed GBM survives more than 5 years. Tumor relapse is nearly universal and the majority of patients do not respond to further systemic therapy. The results from phase II studies conducted with recurrent GBM patients have not translated to successful confirmatory studies and thus we have reached a significant roadblock in the development of new treatments for patients with recurrent GBM. The development of new, active, and potentially targeted drugs for the treatment of recurrent GBM represents a major unmet need. The incorporation of diagnostic/companion biomarker combinations into the phase II studies and appropriate stratification of the patients is lagging significantly behind other larger cancer groups such as breast, non-small cell lung cancer, and melanoma. We herein carried out a systematic review of the phase II clinical studies conducted in patients with recurrent GBM (2010-2013 inclusive) to assess the degree of biomarker incorporation within the clinical trial design.