Hypo-fractionated accelerated radiotherapy with concurrent and maintenance temozolomide in newly diagnosed glioblastoma: updated results from phase II HART-GBM trial

Updates for newly diagnosed and recurrent glioblastoma: a review of recent clinical trials

PURPOSE OF REVIEW

Glioblastoma (GBM) is the most common and devastating primary malignant brain tumor. We summarize recent advances in radiotherapy, immunotherapy, and targeted therapy approaches for the treatment of newly diagnosed and recurrent glioblastoma. We also introduce ongoing clinical trials.

RECENT FINDINGS

Recent clinical trials have explored multiple novel strategies to treat GBM including the use of oncoviruses, chimeric antigen receptor (CAR) T cell therapy, vaccines, radiotherapy, and novel drug delivery techniques to improves drug penetrance across the blood brain barrier. Approaches to improve drug delivery to brain tumors have the potential to expand treatment options of existing therapies that otherwise have poor brain tumor penetrance. Immunotherapy has been of keen interest in both newly diagnosed and recurrent glioblastoma. Vaccines SurVaxM and DCVax-L have shown initial promise in phase II and III trials, respectively. CAR T cell therapy trials are in their early phases but hold promise in both newly diagnosed and recurrent glioblastoma.

SUMMARY

Although progress to improve outcomes for GBM patients has been modest, multiple novel strategies utilizing combination therapies, focused ultrasound to improve drug delivery, and novel immunotherapies are underway.

PROTON THERAPY FOR ADULT-TYPE DIFFUSE GLIOMA: A SYSTEMATIC REVIEW

BACKGROUND

We conducted a systematic review to evaluate outcomes and toxicities associated with proton therapy in the treatment of adult-type diffuse glioma.

METHODS

Following PRISMA guidelines, we searched PubMed for both prospective and retrospective studies on proton therapy for adult diffuse gliomas, including low-grade gliomas and glioblastomas. Survival and toxicity outcomes were reported separately for these glioma types.

RESULTS

Twelve studies from 2013 to 2023 were selected, comprising 3 prospective and 9 retrospective studies. The analysis covered 570 patients with low-grade gliomas and 240 patients with glioblastoma or WHO grade 4 gliomas. Proton therapy was found to be comparable to conventional radiotherapy in terms of survival outcomes. Its main advantage is the ability to minimize radiation exposure to healthy tissues.

DISCUSSION

Proton therapy offers comparable survival outcomes to conventional radiotherapy for adult diffuse gliomas and may enhance treatment tolerance, especially regarding neurocognitive function. A major limitation of this review is the predominance of retrospective studies. Future research should ensure rigorous patient selection and adhere to the latest WHO 2021 classification.

Simultaneous boost radiotherapy versus conventional dose radiotherapy for patients with newly diagnosed glioblastoma: a multi-institutional analysis

We compared survival outcomes of high-dose concomitant boost radiotherapy (HDCBRT) and conventional dose radiotherapy (CRT) for newly diagnosed glioblastoma (GB). Patients treated with intensity-modulated radiation therapy for newly diagnosed GB were included. In HDCBRT, specific targets received 69, 60, and 51 Gy in 30 fractions, while 60 Gy in 30 fractions was administered with a standard radiotherapy method in CRT. Overall survival (OS) and progression-free survival (PFS) were compared using the Log-rank test, followed by multivariate Cox analysis. The inverse probability of treatment weighting (IPTW) method was also applied to each analysis. Among 102 eligible patients, 45 received HDCBRT and 57 received CRT. With a median follow-up of 16 months, the median survival times of OS and PFS were 21 and 9 months, respectively. No significant differences were observed in OS or PFS in the Kaplan-Meier analyses. In the multivariate analysis, HDCBRT correlated with improved OS (hazard ratio, 0.49; 95% confidence interval, 0.27-0.90; P = 0.021), and this result remained consistent after IPTW adjustments (P = 0.028). Conversely, dose suppression due to the proximity of normal tissues and IMRT field correlated with worse OS and PFS (P = 0.008 and 0.049, respectively). A prospective study with a stricter protocol is warranted to validate the efficacy of HDCBRT for GB.

Treatment Outcomes after Dose-Escalated Moderately Hypofractionated Radiotherapy for Frail Patients with High-Grade Glioma

For high-grade glioma (HGG) patients with old age or poor performance status, hypofractionated radiotherapy (hypoRT) in 10-15 fractions is recommended. Also, limited data exist on the impact of salvage treatment after progression in frail patients. We retrospectively analyzed the outcomes of dose-escalated hypoRT in 40 frail HGG patients who were treated with hypoRT between 2013 and 2021. With a median biologically effective dose of 71.7 Gy, a total dose of 56 Gy in 20 fractions was the most frequently used regimen (53.7%). The median age and Karnofsky Performance Status of patients were 74 years and 70, respectively. Most patients (n = 31, 77.5%) were diagnosed with glioblastoma, IDH-wildtype, CNS WHO grade 4. Only 10 (25.0%) patients underwent surgical resection, and 28 (70.0%) patients received concurrent temozolomide during hypoRT. With a median follow-up of 9.7 months, the median overall survival (OS) was 12.2 months. Of the 30 (75.0%) patients with disease progression, only 12 patients received salvage treatment. The OS after progression differed significantly depending on salvage treatment (median OS, 9.6 vs. 4.6 months, p = 0.032). Dose-escalated hypoRT in 20 fractions produced survival outcomes outperforming historical data for frail patients.