P11.51.B Initial temozolomide monotherapy without radiotherapy might be of limited benefit in the treatment of astrocytoma, IDH-mutant, CNS WHO grade 2 and 3

Background

The role of temozolomide chemotherapy alone in isocitrate dehydrogenase (IDH-) mutant astrocytomas has not been conclusively determined. Radiotherapy might be superior to temozolomide alone. Recent studies have linked temozolomide therapy with poor clinical course and induction of hypermutation in IDH-mutant gliomas.

Material and Methods

In this retrospective, single-center study, 183 patients with astrocytoma, IDH-mutant, CNS WHO grade 2 or 3 according to WHO 2021 and diagnosed between 2000 and 2019 were included. Patients initially monitored by means of a wait-and-scan strategy, or treated with radiotherapy alone, or receiving temozolomide alone after histological sampling through biopsy or tumor resection were studied. Patient-related, clinical and imaging data were correlated with progression-free and overall survival. A matched-pair analysis accounting for post-surgical tumor volume was conducted.

Results

No significant differences in median age and clinical status at diagnosis was seen. WHO grades were balanced between patients treated with radiotherapy and temozolomide, but the proportion of WHO grade 2 gliomas was higher in the wait-and-scan cohort. Radiotherapy was associated with significantly longer overall survival than temozolomide (in years, 14.4 vs 10.7; p=0.02) and longer progression-free survival than temozolomide (in years, 6.2 vs 3.4, p=0.02) and wait-and-scan strategies (in years, 6.2 vs 4; p=0.03). Comparing wait-and-scan with temozolomide, survival was significantly longer in the wait-and-scan cohort (in years, not reached vs 10.7, p<0.0001). An analysis of WHO grade 2 astrocytomas only also showed superior survival in the wait-and-scan cohort as compared to temozolomide (p=0.02). Of note PFS was similar overall and in WHO grade 2 astrocytomas.

Conclusion

The results suggest superiority of radiotherapy alone over temozolomide alone or wait-and-scan strategies in IDH-mutant WHO grade 2 and 3. Recent study results indicating that temozolomide might compromise prognosis in some IDH-mutant gliomas might be supported by our data, although caution in interpretation of retrospective data is required. The potential negative effects may only be apparent in the long-term.

P04.22 Tumor treating fields in high-grade glioma patients: A retrospective single-center study

BACKGROUND

Tumor-treating fields (TTFields) are a modern anti-mitotic, non-invasive therapy for the treatment of patients with recurrent and newly diagnosed glioblastoma multiforme (GBM). In Europe, Optune® recieved in 2015 the CE certification. TTFields are a low-intensity (1–3 V/cm) approved therapeutic modality using a non-invasive application of intermediate frequency (200 kHz) alternating electric fields through four transducer arrays directly applied to the skin. The EF-14 study has shown that the addition of TTFields to temozolomide chemotherapy in patients with newly diagnosed GBM significantly improved overall survival (OS) and progression-free survival (PFS) without additional adverse events, apart from mild to moderate skin irritations (Stupp et al., JAMA 2017).

MATERIAL

We retrospectively analyzed data from TTFields-treated patients (2015–2020) that were treated at our department. Patient characteristics such as MGMT promoter methylation status, age, and diagnosis, as well as treatment duration and TTFields therapy usage, were evaluated for this study.

RESULTS

29 patients were treated with TTFields therapy between 2015 and 2020 at our hospital. Most patients received TTFields as primary treatment together with temozolomide maintenance therapy. In detail, 48% of patients were diagnosed with newly diagnosed GBM, 41% received TTFields therapy after tumor recurrence and 10% were diagnosed with other high-grade gliomas. In summary, patients could integrate TTFields therapy into their daily life and showed high adherence to the therapy.Particularly, one of our patients (with MGMT-promoter methylation positive) receives TTFields therapy now for almost 1229 days (approx. 41 months) and is still on therapy. Additionally, this patient shows a high usage rate of 86% indicating well integration of the therapy into daily life.

CONCLUSION

Taken together, our data provided the outcomes of using TTFields together with chemotherapy in the treatment of recurrent and newly diagnosed GBM in our department. Therapy with TTFields has been showing to provide significant clinical benefit for GBM patients.

P14.02 Influence of individual CpG methylation status on outcome in adult patients with glioblastoma multiforme receiving alkylating agent treatment

Background: Methylation of the O-6-methylguanine-DNA methyltransferase (MGMT) promotor causes gene silencing and has been associated with a favourable prognosis in patients with glioblastoma multiforme (GBM) receiving alkylating chemotherapy. However, analysis of MGMT promotor methylation is usually reported as a cut-off depending on the results of the correspondent CpG site testing. This approach disregards a possible heterogeneity concerning the methylation status within the individual CpG sites and its possible association with prognosis in GBM patients. The current study aimed at elucidating the association between methylation of CpG sites 74–98 within the MGMT promotor region and outcome in GBM patients receiving alkylating agents.

Material and Methods: Individual methylation status of 230 patients with histologically proven GBM following concomitant radio-chemotherapy with TMZ after stereotactic biopsy or open tumor resection (OTR) was assessed by the Sanger sequencing (Sseq) approach. Methylation of CpG sites 74–98 within the MGMT promotor region was defined according to a ratio of cytosine /thymine peak >50%. The total number of methylated CpG sites as well as clinical factors such as age, Karnofsky Performance Score (KPS) and mode of surgical procedure were correlated with outcome using proportional hazards models. In a subset of 34 patients, a correlation between individual CpG methylation and MGMT mRNA expression was performed.

Results: Median progression-free (PFS) and overall survival (OS) were 7.8 and 14.6 months, respectively. Alongside younger age, KPS> 80 and OTR, the cumulative total number of methylated loci within the CpG sites 74–98 was strongly associated with both PFS and OS and retained its prognostic influence on outcome in multivariate models (p <0.001). Furthermore, a linear coherence between the total number of methylated CpG sites 74–98 and survival parameters could be observed. Moreover, low number of methylated CpG sites was observed in tumor specimen with a high mRNA expression and vice versa (Spearman correlation coefficient: -0.62).

Conclusion: In contrast to the concept of dichotomizing the MGMT promotor status into ‘methylated’ and ‘non-methylated’, our approach shows a clear heterogeneity within the methylation status of the CpG sites 74–98 within the GBM tumor specimens. Our data suggest a strong correlation between outcome and the total number of methylated CpG sites, thus an up-front analysis of the individual GpC site methylation status prior to initiation of alkylating chemotherapy might help to improve treatment response in GBM patients.

Biological tumour volumes of gliomas in early and standard 20-40 min 18F-FET PET images differ according to IDH mutation status

PURPOSE

For the clinical evaluation of O-(2-¹⁸F-fluoroethyl)-L-tyrosine (¹⁸F-FET) PET images, the use of standard summation images obtained 20-40 min after injection is recommended. However, early summation images obtained 5-15 min after injection have been reported to allow better differentiation between low-grade glioma (LGG) and high-grade glioma (HGG) by capturing the early ¹⁸F-FET uptake peak specific for HGG. We compared early and standard summation images with regard to delineation of the PET-derived biological tumour volume (BTV) in correlation with the molecular genetic profile according the updated 2016 WHO classification.

METHODS

The analysis included 245 patients with newly diagnosed, histologically verified glioma and a positive ¹⁸F-FET PET scan prior to any further treatment. BTVs were delineated during the early 5-15 min and standard 20-40 min time frames using a threshold of 1.6 × background activity and were compared intraindividually. Volume differences between early and late summation images of >20% were considered significant and were correlated with WHO grade and the molecular genetic profile (IDH mutation and 1p/19q codeletion status).

RESULTS

In 52.2% of the patients (128/245), a significant difference in BTV of >20% between early and standard summation images was found. While 44.3% of WHO grade II gliomas (31 of 70) showed a significantly smaller BTV in the early summation images, 35.0% of WHO grade III gliomas (28/80) and 37.9% of WHO grade IV gliomas (36/95) had a significantly larger BTVs. Among IDH-wildtype gliomas, an even higher portion (44.4%, 67/151) showed significantly larger BTVs in the early summation images, which was observed in 5.3% (5/94) of IDH-mutant gliomas only: most of the latter had significantly smaller BTVs in the early summation images, i.e. 51.2% of IDH-mutant gliomas without 1p/19q codeletion (21/41) and 39.6% with 1p/19q codeletion (21/53).

CONCLUSION

BTVs delineated in early and standard summation images differed significantly in more than half of gliomas. While the standard summation images seem appropriate for delineation of LGG as well as IDH-mutant gliomas, a remarkably high percentage of HGG and, particularly, IDH-wildtype gliomas were depicted with significantly larger volumes in early summation images. This finding might be of interest for optimization of treatment planning (e.g. radiotherapy) in accordance with the individual IDH mutation status.

Stereotactic brachytherapy using iodine 125 seeds for the treatment of primary and recurrent anaplastic glioma WHO° III

The current study analyzed the outcome after stereotactic brachytherapy (SBT) using iodine-125 seeds in anaplastic astrocytoma, oligoastrocytoma or oligodendroglioma not suitable for resection. Out of 223 patients harbouring a malignant glioma treated according to a prospective protocol, 172 patients were selected who received SBT to treat a WHO grade III de-novo/residual tumor (n = 99) or a tumor recurrence after multimodal treatment (n = 73). We assessed progression free survival (PFS), overall survival (OS), radiological and clinical outcome and determined prognostic factors using univariate and multivariate regression analyses. The median follow-up time was 38 months. Median OS and median PFS was 28.9 and 21.4 months in the de-novo group vs. 49.4 and 32.6 months in the recurrence group. Recurrent tumors had more frequently (p = 0.01) an oligodendroglial-component compared to de novo tumors. According to cohort-specific univariate analyses KPS at SBT had a significant (p = 0.008) impact on OS in the de-novo group. In the recurrence group, (Cox regression analysis) OS was significantly associated with histology subtype (oligoastro-/oligodendroglioma vs. astrocytoma, p = 0.043). Transient and permanent morbidity (~1 %) was low. For patients unable to undergo surgery due to eloquent tumour location or reduced general condition SBT is an effective treatment option, which does not foreclose additional therapeutic interventions.

Optimized surgical treatment for normal pressure hydrocephalus: comparison between gravitational and differential pressure valves

OBJECTIVES

In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005.

METHODS

The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups.

RESULTS

Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group).

CONCLUSIONS

Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment and urinary incontinency without the risk of overdrainage complications requiring surgical intervention when compared with patients who received differential pressure valves in previous years.

Radiotherapy with and without temozolomide in elderly patients with glioblastoma

BACKGROUND AND PURPOSE

The optimal treatment for elderly patients (age ≥ 70 years) with glioblastoma (GBM) remains controversial. We conducted a retrospective analysis in 43 consecutive elderly patients with glioblastoma who either underwent radiotherapy (RT) or radiotherapy plus concomitant temozolomide (TMZ).

PATIENTS AND METHODS

A total of 43 patients (≥ 70 years of age, median age 75.8 years) with newly diagnosed glioblastoma and a Karnofsky performance status (KPS) ≥ 70 were treated with RT alone (median 60 Gy in 2 Gy single fractions) or RT plus TMZ at a dose of 75 mg/m(2) per day. The two groups were well-balanced; univariate (log-rank test) and multivariate Cox proportional hazards analysis were used to identify relevant prognostic factors.

RESULTS

The median overall survival (mOS) of the entire patient cohort was 264 days (8.8 months) and the median progression-free survival (PFS) was 192 days (6.4 months). The factors age, sex, previous surgery, KPS, and concomitant use of TMZ had no significant influence on OS/PFS; multivariate analysis was performed to obtain adjusted hazard ratios. TMZ use resulted in a trend toward poorer overall survival when applied concomitantly (314 days compared to 192 days within the TMZ group, p = 0.106). The subgroup analysis revealed that TMZ use resulted in significantly worse survival rates in patients with KPS70 (p = 0.027), but for patients with KPS80 this difference was not detectable.

CONCLUSION

TMZ should only be used carefully in elderly patients with unfavorable KPS. In this patient cohort, radiotherapy alone is a reasonable option. Standard RT plus concomitant TMZ may be an advantageous treatment option for elderly patients with newly diagnosed glioblastoma who present with good prognostic factors.