Absence of the MGMT protein as well as methylation of the MGMT promoter predict the sensitivity for temozolomide

Background:

The DNA repair protein O⁶-methylguanine-DNA methyltransferase (MGMT) can cause resistance to the alkylating drug temozolomide (TMZ). The purpose of this study was to determine the relationship between the MGMT status, determined by means of several techniques and methods, and the cytotoxic response to TMZ in 11 glioblastoma multiforme (GBM) cell lines and 5 human tumour cell lines of other origins.

Methods:

Cell survival was analysed by clonogenic assay. The MGMT protein levels were assessed by western blot analysis. The MGMT promoter methylation levels were determined using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and quantitative real-time methylation-specific PCR (qMSP). On the basis of the results of these techniques, six GBM cell lines were selected and subjected to bisulphite sequencing.

Results:

The MGMT protein was detected in all TMZ-resistant cell lines, whereas no MGMT protein could be detected in cell lines that were TMZ sensitive. The MS-MLPA results were able to predict TMZ sensitivity in 9 out of 16 cell lines (56%). The qMSP results matched well with TMZ sensitivity in 11 out of 12 (92%) glioma cell lines. In addition, methylation as detected by bisulphite sequencing seemed to be predictive of TMZ sensitivity in all six cell lines analysed (100%).

Conclusion:

The MGMT protein expression more than MGMT promoter methylation status predicts the response to TMZ in human tumour cell lines.     

IDH mutation and MGMT promoter methylation in glioblastoma: results of a prospective registry

Background

The relative contribution of isocitrate dehydrogenase mutations (mIDH) and O6-methylguanine-DNA methyltransferase promoter methylation (methMGMT) as biomarkers in glioblastoma remain poorly understood.

Methods

We investigated the association between methMGMT and mIDH with progression free survival and overall survival in a prospectively collected molecular registry of 274 glioblastoma patients.

Results

For glioblastoma patients who underwent Temozolomide and Radiation Therapy, OS and PFS was most favorable for those with tumors harboring both mIDH and methMGMT (median OS: 35.8 mo, median PFS: 27.5 mo); patients afflicted glioblastomas with either mIDH or methMGMT exhibited intermediate OS and PFS (mOS: 36 and 17.1 mo; mPFS: 12.2 mo and 9.9 mo, respectively); poorest OS and PFS was observed in wild type IDH1 (wtIDH1) glioblastomas that were MGMT promoter unmethylated (mOS: 15 mo, mPFS: 9.7 mo). For patients with wtIDH glioblastomas, TMZ+RT was associated with improved OS and PFS relative to patients treated with RT (OS: 15.4 mo v 9.6 mo, p < 0.001; PFS: 9.9 mo v 6.5 mo, p < 0.001). While TMZ+RT and RT treated mIDH patients exhibited improved overall survival relative to those with wtIDH, there were no differences between the TMZ+RT or RT group. These results suggest that mIDH1 conferred resistance to TMZ. Supporting this hypothesis, exogenous expression of mIDH1 in independent astrocytoma/glioblastoma lines resulted in a 3–10 fold increase in TMZ resistance after long-term passage.

Conclusion

Our study demonstrates IDH mutation and MGMT promoter methylation status independently associate with favorable outcome in TMZ+RT treated glioblastoma patients. However, these biomarkers differentially impact clinical TMZ response.     

Efficacy of protracted temozolomide dosing is limited in MGMT unmethylated GBM xenograft models

Background

Temozolomide (TMZ) is important chemotherapy for glioblastoma multiforme (GBM), but the optimal dosing schedule is unclear.

Methods

The efficacies of different clinically relevant dosing regimens were compared in a panel of 7 primary GBM xenografts in an intracranial therapy evaluation model.

Results

Protracted TMZ therapy (TMZ daily M–F, 3 wk every 4) provided superior survival to a placebo-treated group in 1 of 4 O⁶-DNA methylguanine-methyltransferase (MGMT) promoter hypermethylated lines (GBM12) and none of the 3 MGMT unmethylated lines, while standard therapy (TMZ daily M–F, 1 wk every 4) provided superior survival to the placebo-treated group in 2 of 3 MGMT unmethylated lines (GBM14 and GBM43) and none of the methylated lines. In comparing GBM12, GBM14, and GBM43 intracranial specimens, both GBM14 and GBM43 mice treated with protracted TMZ had a significant elevation in MGMT levels compared with placebo. Similarly, high MGMT was found in a second model of acquired TMZ resistance in GBM14 flank xenografts, and resistance was reversed in vitro by treatment with the MGMT inhibitor O⁶-benzylguanine, demonstrating a mechanistic link between MGMT overexpression and TMZ resistance in this line. Additionally, in an analysis of gene expression data, comparison of parental and TMZ-resistant GBM14 demonstrated enrichment of functional ontologies for cell cycle control within the S, G2, and M phases of the cell cycle and DNA damage checkpoints.

Conclusions

Across the 7 tumor models studied, there was no consistent difference between protracted and standard TMZ regimens. The efficacy of protracted TMZ regimens may be limited in a subset of MGMT unmethylated tumors by induction of MGMT expression.     

MGMT gene promoter methylation correlates with tolerance of temozolomide treatment in melanoma but not with clinical outcome

Background:

Despite limited clinical efficacy, treatment with dacarbazine or temozolomide (TMZ) remains the standard therapy for metastatic melanoma. In glioblastoma, promoter methylation of the counteracting DNA repair enzyme O⁶-methylguanine-DNA-methyltransferase (MGMT) correlates with survival of patients exposed to TMZ in combination with radiotherapy. For melanoma, data are limited and controversial.

Methods:

Biopsy samples from 122 patients with metastatic melanoma being treated with TMZ in two multicenter studies of the Dermatologic Cooperative Oncology Group were investigated for MGMT promoter methylation. We used the COBRA (combined bisulphite restriction analysis) technique to determine aberrant methylation of CpG islands in small amounts of genomic DNA isolated from paraffin-embedded tissue sections. To detect aberrant methylation, bisulphite-treated DNA was amplified by PCR, enzyme restricted, and visualised by gel electrophoresis.

Results:

Correlation with clinical data from 117 evaluable patients in a best-response evaluation indicated no statistically significant association between MGMT promoter methylation status and response. A methylated MGMT promoter was observed in 34.8% of responders and 23.4% of non-responders (P=0.29). In addition, no survival advantage for patients with a methylated MGMT promoter was detectable (P=0.79). Interestingly, we found a significant correlation between MGMT methylation and tolerance of therapy. Patients with a methylated MGMT promoter had more severe adverse events, requiring more TMZ dose reductions or discontinuations (P=0.007; OR 2.7 (95% CI: 1.32–5.7)). Analysis of MGMT promoter methylation comparing primaries and different metastases over the clinical course revealed no statistical difference (P=0.49).

Conclusions:

In advanced melanoma MGMT promoter, methylation correlates with tolerance of therapy, but not with clinical outcome.     

Phase 2 study of dose-intense temozolomide in recurrent glioblastoma

Background

Among patients with glioblastoma (GBM) who progress on standard temozolomide, the optimal therapy is unknown. Resistance to temozolomide is partially mediated by O⁶-methylguanine-DNA methyltransferase (MGMT). Because MGMT may be depleted by prolonged temozolomide administration, dose-intense schedules may overcome resistance.

Methods

This was a multicenter, phase 2, single-arm study of temozolomide (75–100 mg/m²/day) for 21 days of each 28-day cycle. Patients had GBM in first recurrence after standard therapy. The primary end point was 6-month progression-free survival (PFS6).

Results

Fifty-eight participants were accrued, 3 of whom were ineligible for analysis; one withdrew before response assessment. There were 33 men (61%), with a median age of 57 years (range, 25–79 years) and a median Karnofsky performance score of 90 (range, 60–100). Of 47 patients with MGMT methylation results, 36 (65%) had methylated tumors. There were 7 (13%) partial responses, and PFS6 was only 11%. Response and PFS did not depend on MGMT status; MSH2, MLH1, or ERCC1 expression; the number of prior temozolomide cycles; or the time off temozolomide. Treatment was well tolerated, with limited grade 3 neutropenia (n = 2) or thrombocytopenia (n = 2).

Conclusions

Dose-intense temozolomide on this schedule is safe in recurrent GBM. However, efficacy is marginal and predictive biomarkers are needed.     

Response of primary glioblastoma cells to therapy is patient specific and independent of cancer stem cell phenotype

Background

Glioblastoma multiforme (GBM) contains a population of cells that exhibit stem cell phenotypes. These cancer stem cells (CSCs) may be a source of therapeutic resistance, although support for this important concept is limited.

Methods

We determined whether early-passage GBM CSCs respond differently than patient-matched, genotypically similar non-CSCs to clinically relevant single or serial doses of temozolomide (TMZ), radiation therapy (XRT), or alternating TMZ treatment and XRT, which is the standard of care for GBM patients.

Results

Despite the phenotypic differences, including the presence of stem cell markers and formation of intracranial tumors, the CSCs and matched non-CSCs were equally resistant to TMZ in a majority of patients, using 2 independent assays. TMZ response was consistent with methylated O⁶-DNA methylguanine-methyltransferase (MGMT) and MGMT protein levels in both culture types. In contrast, CSCs were unexpectedly more responsive to XRT compared with matched non-CSCs from 2 patients despite having relatively equal resistance to TMZ. However, for the majority of culture pairs from individual patients, responses in CSCs were indistinguishable from non-CSC cultures.

Conclusions

In our patient-matched primary cultures, response to TMZ was tightly linked to the individual tumor''s MGMT status and independent of their phenotypic differences. TMZ and XRT together revealed no additive benefit compared with monotherapy for either culture type, in contrast to the notion that the CSC population is more resistant to XRT. If the tumor cell response in vitro mirrors therapeutic response in larger patient cohorts, these rapid assays in primary cultures could allow ­empirical selection of efficacious therapeutic agents on a patient-specific basis.     

MGMT methylation assessment in glioblastoma: MS-MLPA versus human methylation 450K beadchip array and immunohistochemistry

Purpose

The MGMT gene encodes a DNA repair enzyme that counteracts with chemotherapy efficiency, specifically with alkylating agents such as temozolomide (TMZ). It is well established that MGMT methylation should be screened as a predictive marker for TMZ in glioblastoma, and we thus aimed to determine a reliable and practical diagnostic method of MGMT methylation detection.

Patients and methods

55 glioblastomas were investigated for MGMT methylation status using methylation-specific multiplexed ligation probe amplification (MS-MLPA), illumina human methylation 450K BeadChip array (HM450 K) analysis, and compared to MGMT protein expression by immunohistochemistry (IHC) staining. The methylation status of promoter, intron and all MGMT CpG targeted sites were separately correlated to patient’s survival.

Results

In addition to MS-MLPA and 450 K concordance, our results showed significantly higher overall survival (OS) of patients receiving TMZ and presenting MGMT methylated promoter (mean OS = 21.5 months, p = 0.046). Including all glioblastoma cases and regardless of chemotherapy, MS-MLPA showed significant survival difference between MGMT methylated and unmethylated cases (mean OS = 13, p = 0.021).

Conclusion

We concluded that in glioblastoma, MGMT promoter methylation predicts TMZ sensitivity. This current comparative analysis leads to consider that MS-MLPA is a valuable as HM450 K array for MGMT methylation status screening.

     

Mismatch repair deficiency: a temozolomide resistance factor in medulloblastoma cell lines that is uncommon in primary medulloblastoma tumours

Background:

Tumours are responsive to temozolomide (TMZ) if they are deficient in O⁶-methylguanine-DNA methyltransferase (MGMT), and mismatch repair (MMR) proficient.

Methods:

The effect of TMZ on medulloblastoma (MB) cell killing was analysed with clonogenic survival assays. Expression of DNA repair genes and enzymes was investigated using microarrays, western blot, and immunohistochemistry. DNA sequencing and promoter methylation analysis were employed to investigate the cause of loss of the expression of MMR gene MLH1.

Results:

Temozolomide exhibited potent cytotoxic activity in D425Med (MGMT deficient, MLH1 proficient; IC₅₀=1.7 μℳ), moderate activity against D341Med (MGMT proficient, MLH1 deficient), and DAOY MB cells (MGMT proficient, MLH1 proficient). MGMT inhibitor O⁶-benzylguanine sensitised DAOY, but not D341Med cells to TMZ. Of 12 MB cell lines, D341Med, D283Med, and 1580WÜ cells exhibited MMR deficiency due to MLH1 promoter hypermethylation. DNA sequencing of these cells provided no evidence for somatic genetic alterations in MLH1. Expression analyses of MMR and MGMT in MB revealed that all patient specimens (n=74; expression array, n=61; immunostaining, n=13) are most likely MMR proficient, whereas some tumours had low MGMT expression levels (according to expression array) or were totally MGMT deficient (3 out of 13 according to immunohistochemistry).

Conclusion:

A subset of MB may respond to TMZ as some patient specimens are MGMT deficient, and tumours appear to be MMR proficient.     

Temozolomide is an active agent in children with recurrent medulloblastoma/primitive neuroectodermal tumor: an Italian multi-institutional phase II trial

Background

The aim of this study was to assess the objective response rate (ORR) of children and young adults with recurrent medulloblastoma/primitive neuroectodermal tumor (MB/PNET) treated with temozolomide (TMZ). The secondary purpose was to analyze the toxicity profile of TMZ when administered orally for 5 days in 3 divided daily doses every 28 days.

Methods

Forty-two patients with recurrent MB/PNET, aged 21 years and younger, were recruited. Patients were treated with oral TMZ. Starting doses ranged from 120 to 200 mg/m²/day based on previous treatments. A craniospinal MRI was performed prior to the first cycle of TMZ and following every 2 cycles of treatment.

Results

Median age was 10 years (range, 2–21 years). Forty of 42 patients were assessed for response and toxicity. The objective response rate was 42.5%: 6 patients achieved a complete response, 11 had a partial response, and 10 had stable disease. Progression-free survival rates for all patients at 6 and 12 months were 30% and 7.5%, respectively. Their median overall survival rates at 6 and 12 months were 42.5% and 17.5%, respectively. No major extrahematological effects or life-threatening events were reported. The most common grade 3/4 toxicity included thrombocytopenia (17.5%), neutropenia (7.5%), and anemia (2.5%).

Conclusions

TMZ proved to be an effective agent in children and young adults with MB/PNET, heavily pre-treated, with a tolerable toxicity profile.     

Activity of irinotecan and temozolomide in the presence of O6-methylguanine-DNA methyltransferase inhibition in neuroblastoma pre-clinical models

Background:

The combination of temozolomide (TMZ) and irinotecan is a regimen used in neuroblastoma patients with recurrent disease. O⁶-methylguanine-DNA methyltransferase (MGMT) may have a function in resistance to TMZ. Using neuroblastoma pre-clinical models, we determined whether the inhibition of MGMT by O⁶-benzylguanine (O6-BG) could enhance the anti-tumour activity of TMZ and irinotecan.

Methods:

The cytotoxicity of TMZ and irinotecan, either alone or in combination, was measured in five neuroblastoma cell lines in the presence or absence of O6-BG with a fluorescence-based cell viability assay (DIMSCAN). Anti-tumour activity was measured in three neuroblastoma xenograft models.

Results:

MGMT mRNA and protein were expressed in 9 out of 10 examined cell lines. Pretreatment of cells with 25 μ O6-BG decreased MGMT protein expression and enhanced The TMZ cytotoxicity by up to 0.3–1.4 logs in four out of five tested cell lines. TMZ (25 mg kg⁻¹ per day for 5 days every 3 weeks for four cycles) did not significantly improve mice survival, whereas the same schedule of irinotecan (7.5 mg kg⁻¹ per day) significantly improved survival (P<0.0001) in all three xenograft models. Combining O6-BG and/or TMZ with irinotecan further enhanced survival.

Conclusion:

Our in vitro and in vivo findings suggest that irinotecan drives the activity of irinotecan and TMZ in recurrent neuroblastoma. Inhibitors of MGMT warrant further investigation for enhancing the activity of regimens that include TMZ.     

Bevacizumab in Combination With Radiotherapy and Temozolomide for Patients With Newly Diagnosed Glioblastoma Multiforme

Background.

Patients with a newly diagnosed glioblastoma multiforme (GBM) have a high risk of recurrent disease with a dismal outcome despite intensive treatment of sequential surgery and chemoradiotherapy with temozolomide (TMZ), followed by TMZ as a single agent. Bevacizumab (BV) may increase response rates to chemotherapy in the recurrent treatment setting of GBM. We hypothesized that a neoadjuvant treatment strategy for patients with newly diagnosed GBM using chemoradiotherapy plus BV would improve resectability and thus survival. We performed a phase II trial of the treatment strategy of BV plus chemoradiation to determine the safety of this combination in patients who had already undergone primary surgery for their GBM.

Methods.

After a biopsy (6 patients) or a resection (13 patients) of a newly diagnosed GBM, 19 patients received radiotherapy (30 fractions of 2 Gy) in combination with daily TMZ 75 mg/m² and BV 10 mg/kg on days 1, 14, and 28, followed by 6 monthly cycles of TMZ 150–200 mg/m² on days 1–5.

Results.

The overall response rate was 26%. Three patients had a complete response after resection, and in two patients, a complete response after resection followed by chemoradiation plus BV was seen. No grade 3–4 toxicities were observed during combination treatment. The median progression-free survival was 9.6 months (95% confidence interval [CI]: 4.3–14.4 months). The median overall survival was 16 months (95% CI: 8.1–26.3 months), similar to a matched control group that received standard chemoradiotherapy from our institution.

Conclusion.

Combination of bevacizumab with radiotherapy and TMZ is safe and feasible in patients with newly diagnosed GBM, but because of low response rates, this treatment strategy does not favor a neoadjuvant approach.     

Frequent MGMT (0(6)-methylguanine-DNA methyltransferase) hypermethylation in long-term survivors of glioblastoma: a single institution experience

Background

The aim of this retrospective study was to analyse the MGMT (0⁶-methylguanine-DNA methyltransferase) promoter methylation status in long-term surviving (≥ 3 years) patients with glioblastoma multiforme (GBM).

Methods

The methylation status of the MGMT promoter was determined by bisulfite modification of the DNA and subsequent methylation-specific polymerase-chain-reaction (MSP). DNA was extracted from routinely formalin-fixed and paraffin-embedded tumour tissue samples.

Results

MSP yielded interpretable results in only 14 of 33 (42%) long-term surviving patients with GBM. A methylated band was seen in 3 of 14, methylated as well as unmethylated bands in 8 of 14 and an only unmethylated band in 3 of 14 patients, thus, yielding MGMT promoter methylation in 11 of 14 patients. The two groups of patients with methylated and unmethylated MGMT promoter status were too small to draw any firm statistical conclusions.

Conclusions

Long-term surviving patients with GBM have very frequently intratumoural MGMT promoter methylation. This phenomenon discriminates long-term survivors from a non-selected group of patients with GBM. The standardization of the MSP for the determination of the MGMT promoter methylation status seems to be necessary in order to make this methodology a more reliable one.     

A phase I trial of veliparib (ABT-888) and temozolomide in children with recurrent CNS tumors: a Pediatric Brain Tumor Consortium report

Background

A phase I trial of veliparib (ABT-888), an oral poly(ADP-ribose) polymerase (PARP) inhibitor, and temozolomide (TMZ) was conducted in children with recurrent brain tumors to (i) estimate the maximum tolerated doses (MTDs) or recommended phase II doses (RP2Ds) of veliparib and TMZ; (ii) describe the toxicities of this regimen; and (iii) evaluate the plasma pharmacokinetic parameters and extent of PARP inhibition in peripheral blood mononuclear cells (PBMCs) following veliparib.

Methods

TMZ was given once daily and veliparib twice daily for 5 days every 28 days. Veliparib concentrations and poly(ADP-ribose) (PAR) levels in PBMCs were measured on days 1 and 4. Analysis of pharmacokinetic and PBMC PAR levels were performed twice during study conduct to rationally guide dose modifications and to determine biologically optimal MTD/RP2D.

Results

Twenty-nine evaluable patients were enrolled. Myelosuppression (grade 4 neutropenia and thrombocytopenia) were dose limiting. The RP2Ds are veliparib 25 mg/m² b.i.d. and TMZ 135 mg/m²/d. Only 2 out of 12 patients treated at RP2Ds experienced dose-limiting toxicities. Although no objective response was observed, 4 patients had stable disease >6 months in duration, including 1 with glioblastoma multiforme and 1 with ependymoma. At the RP2D of veliparib, pediatric pharmacokinetic parameters were similar to those in adults.

Conclusions

Veliparib and TMZ at the RP2D were well tolerated in children with recurrent brain tumors. A phase I/II trial to evaluate the tolerability and efficacy of veliparib, TMZ, and radiation in children with newly diagnosed brainstem gliomas is in progress.     

Phase 1b study of lenvatinib (E7080) in combination with temozolomide for treatment of advanced melanoma

Objective and Methods

In this phase 1b study, patients with stage 4 or unresectable stage 3 melanoma were treated with escalating doses of lenvatinib (once daily) and temozolomide (TMZ) (days 1–5) in 28-day cycles, to determine the maximum tolerated dose (MTD) of the combination. Dose Level (DL)1: lenvatinib 20 mg, TMZ 100 mg/m²; DL2: lenvatinib 24 mg, TMZ 100 mg/m²; DL3: lenvatinib 24 mg, TMZ 150 mg/m². Adverse events (AEs) were recorded and tumor response assessed per RECIST 1.0.

Results

Dose-limiting toxicity occurred in 1 of 32 treated patients (DL1); MTD was not reached. The highest dose administered was lenvatinib 24 mg + TMZ 150 mg/m². Most common treatment-related AEs included fatigue (56.3%), hypertension (53.1%), and proteinuria (46.9%). Overall objective response rate was 18.8% (6 patients), all partial response; (DL1, n = 1; DL3, n = 5). Stable disease (SD) ≥ 16 weeks was observed in 28.1% of patients (DL1 and DL2, n = 1 each; DL3, n = 7); 12.5% of patients had SD ≥ 23 weeks. Single and repeat-dose pharmacokinetics of lenvatinib were comparable across cycles and with concomitant TMZ administration.

Conclusion

Lenvatinib 24 mg/day + TMZ 150 mg/m²/day (days 1–5) demonstrated modest clinical activity, an acceptable safety profile, and was administered without worsening of either lenvatinib- or TMZ-related toxicities in this patient group.     

Combined analysis of O6-methylguanine-DNA methyltransferase protein expression and promoter methylation provides optimized prognostication of glioblastoma outcome

Background

Promoter methylation of the DNA repair gene, O-6-methylguanine-DNA methyltransferase (MGMT), is associated with improved treatment outcome for newly diagnosed glioblastoma (GBM) treated with standard chemoradiation. To determine the prognostic significance of MGMT protein expression as assessed by immunohistochemistry (IHC) and its relationship with methylation, we analyzed MGMT expression and promoter methylation with survival in a retrospective patient cohort.

Methods

We identified 418 patients with newly diagnosed GBM at University of California Los Angeles Kaiser Permanente Los Angeles, nearly all of whom received chemoradiation, and determined MGMT expression by IHC, and MGMT promoter methylation by methylation-specific PCR (MSP) and bisulfite sequencing (BiSEQ) of 24 neighboring CpG sites.

Results

With use of the median percentage of cells staining by IHC as the threshold, patients with <30% staining had progression-free survival (PFS) of 10.9 months and overall survival (OS) of 20.5 months, compared with PFS of 7.8 months (P < .0001) and OS of 16.7 months (P < .0001) among patients with ≥30% staining. Inter- and intrareader correlation of IHC staining was high. Promoter methylation status by MSP was correlated with IHC staining. However, low IHC staining was frequently observed in the absence of promoter methylation. Increased methylation density determined by BiSEQ correlated with both decreased IHC staining and increased survival, providing a practical semiquantitative alternative to MSP. On the basis of multivariate analysis validated by bootstrap analysis, patients with tandem promoter methylation and low expression demonstrated improved OS and PFS, compared with the other combinations.

Conclusions

Optimal assessment of MGMT status as a prognostic biomarker for patients with newly diagnosed GBM treated with chemoradiation requires determination of both promoter methylation and IHC protein expression.     

Time trends in glioblastoma multiforme survival: the role of temozolomide

Background

In 2005, maximum safe surgical resection, followed by radiotherapy with concomitant temozolomide (TMZ), followed by adjuvant TMZ became the standard of care for glioblastoma (GBM). Furthermore, a modest, but meaningful, population-based survival improvement for GBM patients occurred in the US between 1999 (when TMZ was first introduced) and 2008. We hypothesized that TMZ usage explained this GBM survival improvement.

Methods

We used national Veterans Health Adminis-tration (VHA) databases to construct a cohort of GBM patients, with detailed treatment information, diagnosed 1997–2008 (n = 1645). We compared survival across 3 periods of diagnosis (1997–2000, 2001–2004, and 2005–2008) using Kaplan–Meier curves. We used proportional hazards models to calculate period hazard rate ratios (HRs) and 95% confidence intervals (CIs), adjusted for demographic, clinical, and treatment covariates.

Results

Survival increased over calendar time (stratified log-rank P < .0001). After adjusting for age and Charlson comorbidity score, for cases diagnosed in 2005–2008 versus 1997–2000, the HR was 0.72 (95% CI, 0.64–0.82; p-trend < .0001). Sequentially adding non-TMZ treatment variables (ie, surgery, radiotherapy, non-TMZ chemotherapy) to the model did not change this result. However, adding TMZ to the model containing age, Charlson comorbidity score, and all non-TMZ treatments eliminated the period effect entirely (HR = 1.01; 95% CI, 0.86–1.19; p-trend = 0.84).

Conclusions

The observed survival improvement among GBM patients diagnosed in the VHA system between 1997 and 2008 was completely explained by TMZ. Similar studies in other populations are warranted to test the generalizability of our finding to other patient cohorts and health care settings.     

Medulloblastoma subgroup-specific outcomes in irradiated children: who are the true high-risk patients?

Background

The advent of integrated genomics has fundamentally changed our understanding of medulloblastoma. Although survival differences exist among the 4 principal subgroups, this has yet to be elucidated in a North American cohort of irradiated patients.

Methods

Ninety-two consecutive patients between the ages of 3 and 17 treated with surgery, craniospinal irradiation, and chemotherapy were identified at the Hospital for Sick Children. Molecular subgrouping was performed using nanoString.

Results

Two treatment periods were identified: prior to 2006 as per the protocols of the Children''s Oncology Group, and after 2006 per the St Jude Medulloblastoma 03 protocol. Five-year progression-free survival (PFS) over the entire cohort was 0.801 (95% CI: 0.692–0.875) with no significant difference between treatment protocols. Strikingly, we found that Group 4 patients had excellent 5-year PFS of 0.959 (95% CI: 0.744–0.994) for average risk and 0.887 (95% CI: 0.727–0.956) across all Group 4 patients. Group 3 patients had 5-year PFS of 0.733 (95% CI: 0.436–0.891). Sonic hedgehog patients did poorly across both treatment protocols, with 5-year PFS of 0.613 (95% CI: 0.333–0.804), likely owing to a high proportion of TP53 mutated patients in this age group.

Conclusions

In a cohort of irradiated patients over 3 years of age, PFS for Group 4 patients was significantly improved compared with initial reports. The impact of subgroup affiliation in these children needs to be assessed in large prospectively treated cooperative protocols to determine if more than just WNT patients can be safely selected for de-escalation of therapy.     

Phase II trial of 7 days on/7 days off temozolmide for recurrent high-grade glioma

Background

A phase II trial was performed to evaluate the efficacy of a dose-dense, 7 days on/7 days off schedule of temozolomide for patients with recurrent high-grade gliomas (HGG).

Methods

Sixty patients with recurrent HGG received temozolomide at 150 mg/m²/day on days 1–7 and days 15–21 during each 4-week cycle. The primary endpoint was 6-month progression-free survival (PFS-6), with a secondary endpoint of overall survival (OS). A further exploratory objective included the investigation of whether methylation status of the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter within tumor tissue predicted outcomes.

Results

Among patients with glioblastoma (n = 40), PFS-6 was 10% (95% CI, 3%–24%) with median OS of 21.6 weeks (95% CI, 16.9–30.6 weeks). PFS-6 for grade III glioma patients (n = 20) was 50% (95% CI, 27%–73%), and median OS was 100.6 weeks (95% CI, 67 weeks to not reached). There were trends towards longer PFS and OS with MGMT promoter methylation (log-rank test; P = .06 for PFS; P = .07 for OS). Additionally, bevacizumab-naïve glioblastoma patients had significantly longer PFS and OS (median PFS was 8.07 weeks [95% CI, 8 weeks to not reached] vs 7.57 weeks [95% CI, 7.29–8.29 weeks], log-rank test, P < .001; median OS was 62 weeks [26.1 weeks to not reached] vs 18.2 weeks [13.9–27.3 weeks], log-rank test, P < .001).

Conclusions

The dose-dense temozolomide regimen was well tolerated, although it has no significant activity in this population. Clinical trials.gov identified. {"type":"clinical-trial","attrs":{"text":"NCT00619112","term_id":"NCT00619112"}}NCT00619112 (available at http://clinicaltrials.gov/ct2/show/{"type":"clinical-trial","attrs":{"text":"NCT00619112","term_id":"NCT00619112"}}NCT00619112).     

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia

Background:

Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS).

Methods:

A case–control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated.

Results:

Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47–11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20–0.91).

Conclusion:

Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.     

Phase I study of sorafenib combined with radiation therapy and temozolomide as first-line treatment of high-grade glioma

Background:

Sorafenib (Sb) is a multiple kinase inhibitor targeting both tumour cell proliferation and angiogenesis that may further act as a potent radiosensitizer by arresting cells in the most radiosensitive cell cycle phase. This phase I open-label, noncontrolled dose escalation study was performed to determine the safety and maximum tolerated dose (MTD) of Sb in combination with radiation therapy (RT) and temozolomide (TMZ) in 17 patients with newly diagnosed high-grade glioma.

Methods:

Patients were treated with RT (60 Gy in 2 Gy fractions) combined with TMZ 75 mg m⁻² daily, and Sb administered at three dose levels (200 mg daily, 200 mg BID, and 400 mg BID) starting on day 8 of RT. Thirty days after the end of RT, patients received monthly TMZ (150–200 mg m⁻² D1–5/28) and Sb (400 mg BID). Pharmacokinetic (PK) analyses were performed on day 8 (TMZ) and on day 21 (TMZ&Sb) (Clinicaltrials ID: {"type":"clinical-trial","attrs":{"text":"NCT00884416","term_id":"NCT00884416"}}NCT00884416).

Results:

The MTD of Sb was established at 200 mg BID. Dose-limiting toxicities included thrombocytopenia (two patients), diarrhoea (one patient) and hypercholesterolaemia (one patient). Sb administration did not affect the mean area under the curve_(0–24) and mean C_max of TMZ and its metabolite 5-amino-imidazole-4-carboxamide (AIC). T_max of both TMZ and AIC was delayed from 0.75 (TMZ alone) to 1.5 h (combined TMZ/Sb). The median progression-free survival was 7.9 months (95% confidence interval (CI): 5.4–14.55), and the median overall survival was 17.8 months (95% CI: 14.7–25.6).

Conclusions:

Although Sb can be combined with RT and TMZ, significant side effects and moderate outcome results do not support further clinical development in malignant gliomas. The robust PK data of the TMZ/Sb combination could be useful in other cancer settings.