J Neurooncol (2013) 112:277–283 DOI 10.1007/s11060-013-1060-3
CLINICAL STUDY
The value of temozolomide in combination with radiotherapy during standard treatment for newly diagnosed glioblastoma Chul-Kee Park • Se-Hoon Lee • Tae Min Kim Seung Hong Choi • Sung-Hye Park • Dae Seog Heo • Il Han Kim • Hee-Won Jung
•
Received: 12 April 2012 / Accepted: 22 January 2013 / Published online: 2 February 2013 Ó Springer Science+Business Media New York 2013
Abstract The current best standard care for glioblastoma still has limitations and unsatisfactory outcomes in patients with an unmethylated O-6-methylguanine-DNA methyltransferase (MGMT) promoter. Whether the effects of temozolomide are primarily due to its concomitant use with radiotherapy or are also mediated by their independent use in the adjuvant phase remain unclear. To validate the concomitant use of temozolomide in the standard protocol, we compared the overall survival of two prospective patient groups: one treated with radiotherapy alone followed by C.-K. Park H.-W. Jung Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea S.-H. Lee (&) T. M. Kim D. S. Heo Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 110-744, South Korea e-mail:
[email protected] S.-H. Lee T. M. Kim D. S. Heo Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea S. H. Choi Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea S.-H. Park Department of Pathology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea I. H. Kim Department of Radiation Oncology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, South Korea
adjuvant temozolomide (RT ? TMZ group) and the other treated with concomitant radiotherapy and temozolomide followed by adjuvant temozolomide (CCRT-TMZ group). Each patient in the RT ? TMZ group (n = 25) was matched with two patients in the CCRT-TMZ group (n = 50) with respect to age, extent of resection, MGMT promoter methylation status, and postsurgical performance status to minimize the influence of confounding factors. In patients with MGMT promoter methylation, the CCRT-TMZ group showed superior overall survival (OS; median, 41.0 months) and progression-free survival (PFS; median, 24.0 months) compared with the RT ? TMZ group. However, the OS and PFS did not differ between the CCRT-TMZ and the RT ? TMZ groups in the patients without MGMT promoter methylation. Although this data is from a retrospective analysis using small number of patients, the study might indicate that concomitant use of temozolomide with radiotherapy is a crucial step in the standard treatment for glioblastoma patients with MGMT promoter methylation. And the use of temozolomide, either concurrently or by adjuvant after radiotherapy, remains a questionable value for those with an unmethylated MGMT promoter. Keywords Glioblastoma Temozolomide Concomitant Adjuvant MGMT
Introduction The current standard treatment for glioblastoma includes surgery followed by radiotherapy concomitant with temozolomide and adjuvant temozolomide [1]. The U.S. Food and Drug Administration approved the concomitant use of temozolomide with radiotherapy for newly diagnosed glioblastoma cases in 2005 based on the landmark study by
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the European Organization for Research and Treatment of Cancer Brain Tumour and Radiation Oncology Groups and the National Cancer Institute of Canada Clinical Trials Group (EORTC/NCIC) and other supportive data favoring survival gains in groups treated with temozolomide plus radiotherapy compared with groups treated with radiotherapy alone [1–5]. The long-term results of the standard treatment involving temozolomide showed a clear survival benefit over radiotherapy alone (2-year, 3-year, and 5-year survival rates of 27.2 vs 10.9 %, 16.0 versus 3.0 % and 9.8 vs 1.9 %, respectively), and the methylation of the O-6methylguanine-DNA methyltransferase (MGMT) promoter was the strongest prognostic marker [6]. However, whether the value of temozolomide in the current standard protocol is primarily due to its concomitant use with radiotherapy or is also mediated by its independent use in the adjuvant phase remains unclear. There has only been one retrospective analysis on the added value of temozolomide at the radiotherapy phase of the standard protocol, but the study did not consider MGMT promoter methylation status. [7] There have been no other reported prospective studies on concomitant radiotherapy with temozolomide plus adjuvant temozolomide compared with radiotherapy alone plus adjuvant temozolomide. To validate the concomitant use of temozolomide in the standard protocol, we compared the results from two prospective patient groups: one treated with radiotherapy alone followed by adjuvant temozolomide (RT ? TMZ group), which was the control arm of a phase III trial [8], and the other treated with radiotherapy concomitant with temozolomide followed by adjuvant temozolomide (CCRT-TMZ group), which was the newly collected prospective observation group. To minimize the influence of confounding factors, each patient in the RT ? TMZ group was matched with two patients in the CCRT-TMZ group with respect to age, extent of resection, MGMT promoter methylation status and postsurgical performance status.
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adjuvant temozolomide between August 1, 2005, and December 31, 2007. Among them, 25 patients who enrolled from our institute had MGMT promoter methylation status data available and were used as the RT ? TMZ group in the present study. A total of 50 patients were selected from the CCRT-TMZ group among those treated with radiotherapy concomitant with temozolomide followed by adjuvant temozolomide between January 1, 2007, and December 31, 2009. The inclusion criteria of the SCNOG/KROG study were as follows: (1) 15–70 years of age with newly diagnosed supratentorial glioblastoma after histological confirmation (World Health Organization [WHO] grade IV astrocytoma); (2) good performance status (Karnofsky performance score of 70 or higher); and (3) adequate hematologic, renal, and hepatic function [8].The same inclusion criteria used for the SCNOG/ KROG study were used for the selection of the CCRTTMZ group,and a 2:1 matching ratio to each patient of the RT ? TMZ group was applied considering the age, extent of resection, MGMT promoter methylation status and postsurgical performance status. A total of 50 patients were selected for the CCRT-TMZ group among the 93 patients screened. Therefore, a total of 75 newly diagnosed glioblastoma patients were analyzed. The RT ? TMZ group received standard conventional radiotherapy for a total dose of 60.0–61.2 Gy to the gross tumor volume followed by 6 cycles of adjuvant temozolomide (150–200 mg/m2) for 5 days every 28 days. The CCRT-TMZ group received the standard protocol for newly diagnosed glioblastoma as previously described [1]. The only difference between the RT ? TMZ and CCRT-TMZ groups was the addition of temozolomide at a dose of 75 mg/m2 per day 7 days a week for 42 consecutive days during radiotherapy in the CCRT-TMZ group. The clinical data and samples registered in Seoul National University Hospital Neuro-oncology database were utilized for the analysis. This study was approved by the Seoul National University Hospital Institutional Review Board. Surveillance and follow-up
Patients and methods Study design and cohorts Our institute participated in the Seoul Clinical NeuroOncology Group (SCNOG)/Korean Radiation Oncology Group (KROG) study of a prospective, randomized, controlled, multicenter phase III trial evaluating the effects of neoadjuvant chemotherapy with nimustine-cisplatin when used in conjunction with radiotherapy plus adjuvant temozolomide in patients with newly diagnosed glioblastoma [8].In that study, a total of 42 patients were randomized into a group treated with radiotherapy alone followed by
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The assessment of the radiological outcome was defined according to Macdonald’s criteria [9]. The detailed instructions for the response assessment have been described previously [8]. For the CCRT-TMZ group, the concept of pseudoprogression was considered for early radiological response assessment [10]. The primary end point of this study was overall survival. The overall survival time was measured from the date of the initial operation to the date of patient death. Progression-free survival and toxic effect data were also collected and included in the analysis. All patients were followed until the time of death; patients who were alive were submitted to censored observations at the last
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follow-up. The toxic effects were graded in accordance with the NCI CTCAE, version 3.0. MGMT promoter methylation The methylation status of the MGMT promoter was analyzed using the methylation-specific polymerase chain reaction (MSP). Prepared DNA was modified by sodium bisulfite treatment using the EZ DNA methylation-Gold KitTM (Catalog No. D5005; Zymo Research, Orange, CA, USA). The primer sequences for the MGMT promoter were as follows: methylated forward: 50 TTT CGA CGT TCG TAG GTT TTC GC 30 ; methylated reverse: 50 GCA CTC TTC CGA AAA CGA AAC G 30 ; unmethylated forward: 50 TTT GTG TTT TGA TGT TTG TAG GTT TTT GT 30 ; and unmethylated reverse: 50 AAC TCC ACA CTC TTC CAA AAA CAA AAC A 30 [11]. The annealing temperature was 64 °C. The resulting PCR products were electrophoresed in 2 % agarose gels and visualized under ultraviolet illumination after staining with ethidium bromide. For the evaluation of the assay results, the control products were examined first. The MGMT gene promoter fragments in the controls were expected at 80 and 92 base pairs for the methylated DNA– methylated primer and unmethylated DNA–unmethylated primer combinations, respectively. The methylated DNA– unmethylated primer and unmethylated DNA–methylated primer controls were not expected to show any bands. If the control results were acceptable, the patient samples were evaluated for the presence of amplification with the methylated and unmethylated primers. The results were interpreted as positive if MGMT gene promoter methylation was detected as an 80-base pair fragment in the gel and negative if MGMT gene promoter methylation was not detected with the methylated primers. If the band was weak, we repeated the experiment and confirmed the positive result if the signal was again observed. Statistical analyses The Kaplan–Meier method was used to estimate the overall survival and progression-free survival distributions. The long rank test (level of significance a = 0.05) was used to identify differences in the overall survival distributions with respect to prognostic variables. These analyses were performed using SPSSÒ version 19.0.
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applied to both cohorts and the key variables were matched, the baseline characteristics were well balanced between the RT ? TMZ and CCRT-TMZ groups. Every patient in each cohort had taken prophylactic valproic acid during the short-term peri-operative period only. No patient had received steroids at baseline. However, there was a disparity in the degree of completion of the adjuvant temozolomide between the groups, especially within the patients with MGMT promoter methylation (Table 2). At the time of the analysis, 24 (96.0 %) patients in the RT ? TMZ group and 37 (74.0 %) patients in the CCRTTMZ group had died. Survival outcome The median overall survival was 17.0 months (95 % CI, 15.8–18.2) for the RT ? TMZ group and 23.0 months (95 % CI, 16.7–29.3) for the CCRT-TMZ group. This difference in overall survival was not significant (Fig. 1a; p = 0.06). However, stratification of the patients by MGMT promoter methylation status showed a significant superior overall survival in the MGMT promoter-methylated patients in the CCRT-TMZ group (Fig. 2, Table 3).The median progression-free survival was 6.0 months (95 % CI, 1.1–10.9) for the RT ? TMZ group and 9.0 months (95 % CI, 5.5–12.5) for the CCRT-TMZ group, and this difference showed borderline significance (Fig. 1b; p = 0.05). The stratification of the patients by MGMT promoter methylation status also showed a significant superior progression-free survival in the MGMT promoter-methylated patients in the CCRT-TMZ group (Table 3).
Table 1 The baseline characteristics of the study cohorts RT ? TMZ group (n = 25)
CCRT-TMZ group (n = 50)
Median (range) Extent of resection
46 (30–68)
49 (28–70)
C95 % resection
10 (40 %)
20 (40 %)
\95 % resection
15 (60 %)
30 (60 %)
7 (28 %)
12 (20 %)
Characteristics Age, years
biopsy only
MGMT promoter methylation Methylated Unmethylated
Results Clinical course The baseline characteristics of each cohort are summarized in Table 1. Because the same inclusion criteria were
7 (28 %)
14 (28 %)
18 (72 %)
36 (72 %)
Performance status ECOG 0
4 (16 %)
7 (14 %)
ECOG 1
15 (60 %)
35 (70 %)
ECOG 2
6 (24 %)
8 (16 %)
MGMT O-6-methylguanine-DNA methyltransferase, ECOG Eastern Cooperative Oncology Group
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Table 2 The differences in the completeness of adjuvant temozolomide treatment between the RT ? TMZ and CCRT-TMZ groups RT ? TMZ group Whole group (n = 25)
CCRT-TMZ group Methylated MGMT promoter (n = 7)
Whole group (n = 50)
Methylated MGMT promoter (n = 14)
TMZ \ 3 cycles
13 (52 %)
5 (71 %)
20 (40 %)
1 (7 %)
TMZ C 3 cycles
12 (48 %)
2 (29 %)
30 (60 %)
13 (93%)
Patients who completed 6 cycles of adjuvant TMZ
9 (36 %)
2 (29 %)
26 (52 %)
12 (86 %)
Patients who did not enter the adjuvant TMZ phase
1 (4 %)
1 (14 %)
8 (13 %)
1 (7 %)
Time of progression The distribution of the disease progression junctures in the patients from the RT ? TMZ and CCRT-TMZ groups is summarized in Fig. 3. In the RT ? TMZ group, 18 (72 %) patients showed disease progression after radiotherapy or during the adjuvant temozolomide phase. The remaining 7 (28 %) patients eventually progressed during the follow-up period. In the CCRT-TMZ group, 25 (50 %) patients showed disease progression after radiotherapy or during the adjuvant temozolomide phase, and 10 (40 %) showed progression during the follow-up period. The remaining 5 (10 %) patients remained progression free at the follow-up periods of 13, 30, 36, 39, and 43 months. A relatively larger proportion of patients showed early progression in the RT ? TMZ group compared with the patients in the CCRT-TMZ group. When MGMT promoter methylation status was considered, differences in the frequent junctures of disease progression between
groups were more prominent in the patients with MGMT promoter methylation (Fig. 3b). Treatment with the CCRTTMZ protocol in patients with MGMT promoter methylation clearly delayed disease progression. In patients with an unmethylated MGMT promoter, little differences in the distribution of disease progression junctures were observed between the RT ? TMZ and CCRT-TMZ groups. Pseudoprogression was observed in 9 patients in the CCRT-TMZ group before the adjuvant temozolomide phase. This number corresponds to 18 % of all patients in the CCRT-TMZ population and 38 % of those who showed radiological progression after the CCRT phase. In the RT ? TMZ group, pseudoprogression was observed in 4 patients, which corresponds to 16 % of all patients in theRT ? TMZ group and 29 % of those who showed radiological progression after RT phase. The salvage treatmentsperformed after disease progression are summarized in Table 4. There was relatively little disparity in the number of patients and modalities receiving
Fig. 1 Kaplan-Meier estimates of overall survival (a) and progression-free survival (b) for the two treatment groups
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Fig. 2 Kaplan-Meier estimates of overall survival in the treatment groups stratified by MGMT promoter methylation status
salvage treatment. Therefore, the salvage treatment likely had no influence on the differences in overall survival between groups. Treatment-related toxicities The treatment-related toxicities that occurred during each treatment phase are summarized in Table 5. There was a relatively low rate of serious toxicities in both groups, and the rates were similar between the groups (16 % in the RT ? TMZ group and 14 % in the CCRT-TMZ group).
Discussion The present study suggests an answer to the question of the outcome of adding adjuvant temozolomide treatment to the control group of the original study by EORTC/NCIC [1, 12] Essentially, patients with a methylated MGMT promoter showed outstanding prognosis when treated with concomitant
radiotherapy and temozolomide followed by adjuvant temozolomide (CCRT-TMZ methylated vs RT ? TMZ methylated, p = 0.02; CCRT-TMZ methylated vs CCRT-TMZ unmethylated, p = 0.00). We did not find significant differences between the other patients in the present study regardless of the treatment protocol or MGMT promoter methylation status (RT ? TMZ unmethylated vs CCRTTMZ unmethylated, p = 0.52; RT ? TMZ methylated vs CCRT-TMZ unmethylated, p = 0.70; RT ? TMZ methylated vs RT ? TMZ unmethylated, p = 0.67; Fig. 2). This trend is similar to the result of the EORTC/NCIC study, although that study reported a marginal significant difference in the overall survival between patients with anunmethylated MGMT promoter treated with radiotherapy only and those treated with concomitant radiotherapy and temozolomide followed by adjuvant temozolomide [12].We also observed that there was a disparity in the degree of completion of the adjuvant temozolomide between the groups, especially within the patients with MGMT promoter methylation (Table 2). In the MGMT promoter-methylated glioblastoma patients, the concurrent use of temozolomide with radiotherapy enabled a sustained stable state, and patients could then complete the adjuvant temozolomide treatment. Thus, the concomitant radiotherapy with temozolomide phase is hypothesized to be a key step for the survival benefit only in MGMT promotermethylated patients based on the significant survival differences between the RT ? TMZ and CCRT-TMZ groups. In addition, the efficacy of adjuvant temozolomide after radiotherapy or chemoradiotherapy is questionable in the patients with MGMT promoter methylation. Further prospective, randomized trials comparing the standard treatment and concomitant radiotherapy with temozolomide only without adjuvant temozolomide in glioblastoma patients with MGMT promoter methylation will address the issue of the efficacy of adjuvant temozolomide. For patients with an unmethylated MGMT promoter, the combined effect of temozolomide to radiotherapy is limited. The result of the present study also provided a more detailed answer to the question of whether the primary benefit of temozolomide is mediated through its concomitant
Table 3 The differences in the overall survival and progression-free survival according to the MGMT promoter methylation status in each study cohort MGMT promoter
Unmethylated (n = 54) Methylated (n = 21)
Treatment group
Overall survival
Progression-free survival
Median (months)
95 % confidence interval
p value 0.53
RT ? TMZ (n = 18)
17.0
14.2–19.8
CCRT-TMZ (n = 36)
18.0
12.8–23.2
RT ? TMZ (n = 7)
17.0
14.4–19.6
CCRT-TMZ (n = 14)
41.0
35.2–46.8
0.02
Median (months)
95 % confidence interval
6.0
1.8–10.2
6.0
3.4–8.6
3.0
1.3–4.7
24.0
18.5–9.5
p value 0.19 0.02
Kaplan–Meier and log rank tests
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Fig. 3 The distribution of the disease progression junctures in the treatment groups (a) and the treatment groups stratified by MGMT promoter methylation status (b) Table 4 Salvage treatment after disease progression Salvage treatment Chemotherapy CPT-11/bevacizumab PCV
RT ? TMZ group (n = 25)
CCRT-TMZ group (n = 45)
10 (40 %)
15 (33 %)
2
7 2
Metronomic temozolomide Others Surgery
1 2
2
1 5 (20 %)
3 13 (29 %)
Surgery only
2
4
Surgery and chemotherapy
3
7
Surgery and re-radiotherapy
1
Surgery and re-radiotherapy and chemotherapy
1
None
10 (40 %)
17 (38 %)
or adjuvant delivery [7] Sher et al. advocated the importance of concomitant radiotherapy with temozolomide compared with adjuvant temozolomide, highlighting the potentiation of the radiation effect by temozolomide even if MGMT information was lacking [7]. Among the possibilities of the mechanism of temozolomide action at the chemoradiotherapy phase, the synergistic effect caused by the independent cytotoxicity of radiotherapy and temozolomide is a more plausible hypothesis than temozolomide as a radiosensitizer because the efficacy of chemoradiotherapy is significant only in the MGMT promoter-methylated patients [13–16]. The ongoing EORTC CATNON trial on high-grade gliomasis expected to provide solid evidence of the value of
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RT ? TMZ group (n = 25)
CCRT-TMZ group (n = 50)
Nonhematologic
Hematologic
Nonhematologic
Hematologic
RT or CCRT phase
2 (8 %)
0
3 (6 %)
0
Adjuvant TMZ phase
2 (8 %)
0
3 (6 %)
1 (2 %)
Total
4 (16 %)
Treatment phase
5
Temozolomide re-challenge Multiple protocols
Table 5 Treatment-related toxicities of NCI CTCAE grade 3 or 4
7 (14 %)
temozolomide treatment and its appropriate application, as the study is composed of 4 randomized groups of radiotherapy alone, radiotherapy followed by adjuvant temozolomide, radiotherapy with concomitant temozolomide, and radiotherapy with both concomitant and adjuvant temozolomide. There are several limitations of the present study. First, although the patients were prospectively collected and the confounding variables were matched in both study groups, the patient group was highly selected, and the number of patients was still insufficient to draw solid conclusions. The small number of patients might have interfered with the significance of overall survival (p = 0.06) or progressionfree survival (p = 0.05) between the RT ? TMZ and CCRT-TMZ groups; clear differences maybe observed with sufficient patient numbers. Second, the proportion of MGMT promoter-methylated patients is smaller (28 %) than that reported for the general glioblastoma population (45 %)
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[17]. Third, the concept of pseudoprogression was not properly applied to the RT ? TMZ group, for which patients were collected between 2005 and 2007. However, we believe that appropriate comparisons could be achieved between the two groups, as they are well balanced and homogeneous despite not being representative of the whole population of glioblastoma patients. In addition, there may be a criticism regarding the significant difference in the number of completed cycles of adjuvant temozolomide between the two groups among MGMT-methylated patients (Table 2). If the TMZ treatment in the RT ? TMZ group was stopped due to unrecognized pseudoprogression, the superior outcome of the CCRT-TMZ group over the RT ? TMZ group may have been due to a longer adjuvant TMZ treatment time rather than concurrent use of TMZ. However, a careful review of the clinical courses of those patients revealed that all six patients (5 in RT ? TMZ, and 1 in CCRT-TMZ) were regarded as true progression. Therefore, the excessive rate of incomplete adjuvant TMZ cycles in the RT ? TMZ group over the CCRT-TMZ group may be due to an insufficient anti-cancer effect as a result of omitting concurrent TMZ during RT. In conclusion, we can claim that the concomitant use of temozolomide with radiotherapy is a crucial step in the standard treatment for glioblastoma patients with MGMT promoter methylation. For glioblastoma patients with an unmethylated MGMT promoter, the value of temozolomide usage is questionable, either concurrently or as an adjuvant after radiotherapy. However, this should be evaluated in further studies. Acknowledgments This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A2003779). No author received financial support in conjunction with the generation of this manuscript. The authors have no personal financial or institutional interest in any of the material described in this article. Disclosure No financial support or relationships that may pose a conflict of interest exist regarding this work.
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