Neurological Symptom Improvement After Re-Irradiation in Patients With Diffuse Intrinsic Pontine Glioma: A Retrospective Analysis of the SIOP-E-HGG/DIPG Project

Re-irradiation for children with diffuse intrinsic pontine glioma and diffuse midline glioma

BACKGROUND AND PURPOSE

Diffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG) are incurable brain malignancies. In this study, we report one of the largest known single-institution cohorts of DIPG/DMG patients undergoing re-irradiation (RT2) to evaluate its effect on survival.

MATERIALS AND METHODS

Children aged less than 18 years treated for DIPG/DMG with initial fractionated photon radiotherapy (RT1) and had subsequent recurrence were retrospectively reviewed. Patients treated with or without RT2 were compared. The primary outcomes were overall survival (OS) from time of recurrence after RT1, and from start of RT2 (for the RT2 group).

RESULTS

A total of 118 children were included, 39 of whom received RT2. Children treated with RT2 had superior OS, with 6-month OS of 66 % vs 22 % in those who did not undergo RT2 (p < 0.0001). Median survivals were 6.9 months for the RT2 group vs 2.7 months for RT1 only. Median time from RT1 to RT2 was 7.7 months; patients with a greater than 1-year latent time between RT1 and RT2 had longer OS from start of RT2 (median 10.9 months vs 5.5 months, p = 0.023). 61 % of those treated with RT2 experienced improvement of neurologic symptoms post-RT2. Multivariate analysis identified younger age, adverse imaging findings on the 4-week post-RT1 reassessment MRI (including pseudoprogression), and the absence of RT2 as poor prognostic factors for OS.

CONCLUSION

Re-irradiation was associated with improved survival and neurological recovery in children with recurrent DIPG and DMG. There is a need to identify novel biomarkers to better select patients who respond best to RT2.

From pre-clinical studies to human treatment with proton-minibeam radiation therapy: adapted Idea, Development, Exploration, Assessment and Long-term evaluation (IDEAL) framework for innovation in radiotherapy

The implementation and spread of new radiation therapy (RT) techniques are often rushed through before or without high-quality proof of a clinical benefit. The framework for phase 1, 2 and 3 trials, ideally designed for pharmaceutical evaluation, is not always appropriate for RT interventions. The IDEAL framework is a five-step process initially developed to enable the rapid implementation of surgical innovations while limiting risks for patients. IDEAL was subsequently adapted to RT. Proton-minibeam radiation therapy (pMBRT) is an innovative RT approach, using an array of parallel thin beams resulting in an outstanding increase in the therapeutic ratio. Cumulative preclinical evidence showed pMBRT was superior to standard RT regarding brain tolerance and provided equivalent or better local control in several glioblastoma models. We decided to adapt IDEAL to pMBRT to accelerate the implementation of this promising new technique in clinical care and present here some examples of possible upcoming studies.

Re-Irradiation for the Progressive Pediatric Diffuse Intrinsic Pontine Glioma: A Report on 109 Children From a Single Center

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a challenging pediatric tumor that frequently progresses within the first year following local radiotherapy. However, several small studies have suggested that re-irradiation may improve quality of life and extend overall survival.

PATIENTS AND METHODS

This retrospective study included 109 children who experienced disease progression ≥3 months after their initial radiotherapy, and subsequently received re-irradiation at a single institution. These patients were compared with a cohort of 60 children, meeting the same criteria, who were treated before adopting the re-irradiation policy and received only the best supportive care (BSC). Most of the re-irradiated children (94%) received first radiation dose as hypofractionation (39 Gy/13 fractions).

RESULTS

The re-irradiation group demonstrated significantly higher overall survival (OS) rates after the first progression, with a 6-month OS of 42% (95% CI: 34%-53%) compared to 16% (95% CI: 8.9%-32%) in the BSC group (p < 0.001). Re-irradiation reduced the hazard of death by more than half (HR = 0.45, p < 0.001). Clinical response (p < 0.001) and radiological response (p = 0.016) were significant predictors of improved survival. While the time from initial radiotherapy to progression (p = 0.059) and higher re-irradiation doses (p = 0.074) were associated with improved OS, these factors did not reach statistical significance but may represent potential prognostic indicators.

CONCLUSION

Re-irradiation improved the OS in children with progression of DIPG and alleviated their signs and symptoms.

Re-irradiation in progressive diffuse infiltrative pontine glioma in children and young adults

PURPOSE

This study aims to assess oncological outcomes in children and young adults with diffuse infiltrative pontine glioma (DIPG) who have progressed after initial radiotherapy (RT), with an emphasis on the role of re-irradiation.

METHODS

Data from 33 patients aged 25 years or younger with progressive disease after initial RT were retrospectively analyzed.

RESULTS

The median age at diagnosis was 8 years (range 4-24 years), and the median initial RT dose was 54 Gy (range 39-54 Gy). The median time between initial RT and progression was 8 months (range 3-40 months). In addition to systemic therapy, 15 patients (46%) received re-irradiation due to progression, with a median dose of 23.4 Gy (range 19.8-36 Gy), while 18 patients (54%) were treated with systemic therapy alone. In patients who received re-irradiation after progression, the 1‑year post-progression overall survival (OS) was significantly higher compared to those treated with systemic therapy alone (27% vs. 0%, p = 0.01). Among the 15 re-irradiated patients, 9 out of 12 with available data (75%) showed improvement in neurological symptoms following re-irradiation. No patient exhibited acute or late RT-related ≥ grade 3 toxicity.

CONCLUSION

Palliative re-irradiation in children and young adults with progressive DIPG after initial RT provides an approximately 3‑month OS benefit and clinical improvement without significant toxicity and should be considered as a standard-of-care approach.

Reirradiation for diffuse intrinsic pontine glioma: prognostic radiomic factors at progression

PURPOSE

Diffuse intrinsic pontine glioma (DIPG) is a lethal pediatric brain tumor. Radiation therapy (RT) is the standard treatment, with reirradiation considered in case of progression. However, the prognostic factors for reirradiation are not well understood. This study aims to investigate the outcomes of DIPG patients undergoing reirradiation and identify clinical and radiomic prognostic factors.

METHODS

We conducted a retrospective analysis of patients with DIPG who underwent reirradiation at our institution between January 2016 and December 2023. Using PyRadiomics, we extracted radiomic features of tumors at the time of progression from FLAIR MRI images and collected clinical data. We used the least absolute shrinkage and selection operator (lasso) for Cox's proportional hazard model with leave-one-out cross-validation to select optimal prognostic factors for survival after reirradiation.

RESULTS

The study included 18 patients who underwent reirradiation at first progression, receiving a total dose of 20 Gy or 24 Gy in 2‑Gy fractions. Reirradiation was well tolerated, with no severe toxicity. Most patients (78%) showed neurological improvement after treatment. Median survival after progression was 29.2 weeks. The Cox model demonstrated a concordance of 0.81 (95% CI: 0.75-0.88), revealing that tumor sphericity and structural gray-level heterogeneity in FLAIR MRI images were associated with longer survival of reirradiated patients.

CONCLUSION

Reirradiation is a safe and effective approach for patients with DIPG. MRI-based radiomic models could be helpful in predicting survival after reirradiation.

Hypofractionated re-irradiation for diffuse intrinsic pontine glioma

BACKGROUND

Re-irradiation (reRT) increases survival in locally recurrent diffuse intrinsic pontine glioma (DIPG). There is no standard dose and fractionation for reRT, but conventional fractionation (CF) is typically used. We report our institutional experience of reRT for DIPG, which includes hypofractionation (HF).

METHODS

We reviewed pediatric patients treated with brainstem reRT for DIPG at our institution from 2012 to 2022. Patients were grouped by HF or CF. Outcomes included steroid use, and overall survival (OS) was measured from both diagnosis and start of reRT.

RESULTS

Of 22 patients who received reRT for DIPG, two did not complete their course due to clinical decline. Of the 20 who completed reRT, the dose was 20-30 Gy in 2-Gy fractions (n = 6) and 30-36 Gy in 3-Gy fractions (n = 14). Median age was 5 years (range: 3-14), median interval since initial RT was 8 months (range: 3-20), and 12 received concurrent bevacizumab. Median OS from diagnosis was 18 months [95% confidence interval: 17-24]. Median OS from start of reRT for HF versus CF was 8.2 and 7.5 months, respectively (p = .20). Thirteen (93%) in the HF group and three (75%) in the CF group tapered pre-treatment steroid dose down or off within 2 months after reRT due to clinical improvement. There was no significant difference in steroid taper between HF and CF (p = .4). No patients developed radionecrosis.

CONCLUSION

reRT with HF achieved survival duration comparable to published outcomes and effectively palliated symptoms. Future investigation of this regimen in the context of new systemic therapies and upfront HF is warranted.

Molecular Characterization and Treatment Approaches for Pediatric H3 K27-Altered Diffuse Midline Glioma: Integrated Systematic Review of Individual Clinical Trial Participant Data

Diffuse midline glioma (DMG), H3 K27-altered are highly aggressive, incurable central nervous system (CNS) tumors. The current standard palliative treatment is radiotherapy, with most children succumbing to the disease in less than one year from the time of diagnosis. Over the past decade, there have been significant advancements in our understanding of these heterogeneous tumors at the molecular level. As a result, most of the newer clinical trials offered utilize more targeted approaches with information derived from the tumor biopsy. In this systematic review, we used individual participant data from seven recent clinical trials published over the past five years that met our inclusion and exclusion criteria to analyze factors that influence overall survival (OS). We found that the most prominent genetic alterations H3.3 (H3F3A) and TP53 were associated with worse OS and that ACVR had a protective effect. In addition, re-irradiation was the only statistically significant treatment modality that showed any survival benefit. Our findings highlight some important characteristics of DMG, H3 K27-altered and their effects on OS along with the importance of continuing to review clinical trial data to improve our therapies for these fatal tumors.

Re-irradiation for recurrent/progressive pediatric brain tumors: from radiobiology to clinical outcomes

INTRODUCTION

Brain tumors are the most common solid tumors in children. Neurosurgical excision, radiotherapy, and/or chemotherapy represent the standard of care in most histopathological types of pediatric central nervous system (CNS) tumors. Even though the successful cure rate is reasonable, some patients may develop recurrence locally or within the neuroaxis.

AREA COVERED

The management of these recurrences is not easy; however, significant advances in neurosurgery, radiation techniques, radiobiology, and the introduction of newer biological therapies, have improved the results of their salvage treatment. In many cases, salvage re-irradiation is feasible and has achieved encouraging results. The results of re-irradiation depend upon several factors. These factors include tumor type, extent of the second surgery, tumor volume, location of the recurrence, time that elapses between the initial treatment, the combination with other treatment agents, relapse, and the initial response to radiotherapy.

EXPERT OPINION

Reviewing the radiobiological basis and clinical outcome of pediatric brain re-irradiation revealed that re-irradiation is safe, feasible, and indicated for recurrent/progressive different tumor types such as; ependymoma, medulloblastoma, diffuse intrinsic pontine glioma (DIPG) and glioblastoma. It is now considered part of the treatment armamentarium for these patients. The challenges and clinical results in treating recurrent pediatric brain tumors were highly documented.

Salvage boron neutron capture therapy for pediatric patients with recurrent diffuse midline glioma

PURPOSE

Pediatric diffuse malignant glioma located in the brainstem was officially named "diffuse midline glioma" (DMG) by the World Health Organization in 2016. For this disease, radical surgery is not beneficial, and the only major treatment strategy is radiotherapy. However, the dose limitations to brainstem tissue mean that treatment by radiotherapy can only control and not eradicate the tumors, and there is no effective treatment for recurrence, resulting in short overall survival of 6-12 months. This paper reports our experience with boron neutron capture therapy (BNCT), a new treatment process, and its efficacy in treating children with recurrent DMG.

METHODS

From September 2019 to July 2022, we treated 6 children affected by recurrent DMG. With the collaboration of Taipei Veteran General Hospital (TVGH) and National Tsing-Hua University (NTHU), each patient received two sessions of BNCT within 1 month.

RESULTS

Among the six patients, three showed partial response and the rest had stable disease after the treatment. The overall survival and recurrence-free survival duration after treatment were 6.39 and 4.35 months, respectively. None of the patients developed severe side effects, and only one patient developed brain necrosis, which was most likely resulted from previous hypofractionated radiotherapy received.

CONCLUSION

BNCT elicited sufficient tumor response with low normal tissue toxicity; it may benefit vulnerable pediatric patients with DMG.

Pediatric diffuse midline glioma H3K27- altered: A complex clinical and biological landscape behind a neatly defined tumor type

The 2021 World Health Organization Classification of Tumors of the Central Nervous System, Fifth Edition (WHO-CNS5), has strengthened the concept of tumor grade as a combination of histologic features and molecular alterations. The WHO-CNS5 tumor type "Diffuse midline glioma, H3K27-altered," classified within the family of "Pediatric-type diffuse high-grade gliomas," incarnates an ideally perfect integrated diagnosis in which location, histology, and genetics clearly define a specific tumor entity. It tries to evenly characterize a group of neoplasms that occur primarily in children and midline structures and that have a dismal prognosis. Such a well-defined pathological categorization has strongly influenced the pediatric oncology community, leading to the uniform treatment of most cases of H3K27-altered diffuse midline gliomas (DMG), based on the simplification that the mutation overrides the histological, radiological, and clinical characteristics of such tumors. Indeed, multiple studies have described pediatric H3K27-altered DMG as incurable tumors. However, in biology and clinical practice, exceptions are frequent and complexity is the rule. First of all, H3K27 mutations have also been found in non-diffuse gliomas. On the other hand, a minority of DMGs are H3K27 wild-type but have a similarly poor prognosis. Furthermore, adult-type tumors may rarely occur in children, and differences in prognosis have emerged between adult and pediatric H3K27-altered DMGs. As well, tumor location can determine differences in the outcome: patients with thalamic and spinal DMG have significantly better survival. Finally, other concomitant molecular alterations in H3K27 gliomas have been shown to influence prognosis. So, when such additional mutations are found, which one should we focus on in order to make the correct clinical decision? Our review of the current literature on pediatric diffuse midline H3K27-altered DMG tries to address such questions. Indeed, H3K27 status has become a fundamental supplement to the histological grading of pediatric gliomas; however, it might not be sufficient alone to exhaustively define the complex biological behavior of DMG in children and might not represent an indication for a unique treatment strategy across all patients, irrespective of age, additional molecular alterations, and tumor location.