Hypofractionated radiotherapy in children with diffuse intrinsic pontine glioma

Nimotuzumab-vinorelbine combination therapy versus other regimens in the treatment of pediatric diffuse intrinsic pontine glioma

PURPOSE

Pediatric diffuse intrinsic pontine glioma (DIPG) is a fatal disease associated with a median survival of < 1 year despite aggressive treatments. This retrospective study analyzed the treatment outcomes of patients aged < 18 years who were diagnosed with DIPG between 2012 and 2022 and who received different chemotherapy regimens.

METHODS

After radiotherapy, patients with DIPG received nimotuzumab-vinorelbine combination or temozolomide-containing therapy. When nimotuzumab was unavailable, it was replaced by vincristine, etoposide, and carboplatin/cyclophosphamide (VECC). Temozolomide was administered as a single agent or a part of the combination chemotherapy comprising temozolomide, irinotecan, and bevacizumab. Furthermore, 1- and 3-year overall survival (OS), progression-free survival (PFS), and median OS and PFS were analyzed.

RESULTS

The median age of 40 patients with DIPG was 97 ± 46.93 (23-213) months; the median follow-up time was 12 months. One and 3-year OS were 35.0% and 7.5%, respectively. Median OS was 12 months in all patients (n = 40), and it was 16, 10, and 11 months in those who received first-line nimotuzumab-vinorelbine combination (n = 13), temozolomide-based (n = 14), and VECC (n = 6) chemotherapy regimens, respectively (p = 0.360). One patient who received gefitinib survived for 16 months. Conversely, patients who never received radiotherapy and any antineoplastic medicamentous therapy (n = 6) had a median OS of 4 months.

CONCLUSION

Nimotuzumab-vinorelbine combination therapy prolonged OS by 6 months compared with temozolomide-containing chemotherapy, although the difference was not statistically significant.

An Update on H3K27M-altered Diffuse Midline Glioma: Diagnostic and Therapeutic Challenges in Clinical Practice

H3K27-altered diffuse midline glioma (DMG H3K27-altered) is a relatively newly-designated WHO entity which primarily affects the midline structures of the central nervous system (CNS), including the brainstem (predominantly pontine region), thalamus, midbrain, or spinal cord, and primarily affects children and young adults. Despite the proximity of these tumors to eloquent areas in the CNS, novel stereotactic approaches have facilitated the ability to obtain tissue diagnoses without significant morbidity, providing molecular diagnostic information in more than half of patients. Conventionally fractionated radiation therapy to a total dose of 54-60 Gy in 27-30 fractions and 24 Gy in 12 fractions play a crucial role in the definitive treatment of these tumors in the primary and salvage settings, respectively. Hypofractionated regimens may allow for accelerated treatment courses in selected patients without jeopardizing disease control or survival. The decision to add concurrent or adjuvant systemic therapy mainly relies on the physicians' experience without solid evidence in the literature in favor of any particular regimen. Recently, novel agents, such as ONC201 have demonstrated promising oncologic outcomes in progressive/recurrent tumors and are currently under investigation in ongoing randomized trials. Given the scarcity of data and well-established guidelines due to the rare nature of the disease, we provide a contemporary overview on the molecular underpinnings of this disease entity, describe the role of radiotherapy and systemic therapy, and present practice management principles based on the published literature.

Focused ultrasound-mediated blood-brain barrier opening is safe and feasible with moderately hypofractionated radiotherapy for brainstem diffuse midline glioma

BACKGROUND

Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood-brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS). Focused ultrasound (FUS) with microbubbles can transiently and non-invasively disrupt the BBB to enhance drug delivery. This study aimed to determine the feasibility of brainstem FUS in combination with clinical doses of RT. We hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT.

METHODS

To establish a safety timeline, we administered FUS to the brainstem of non-tumor bearing mice concurrent with or adjuvant to RT; our findings were validated in a syngeneic brainstem murine model of DMG receiving repeated sonication concurrent with RT. The brainstems of male B6 (Cg)-Tyrc-2J/J albino mice were intracranially injected with mouse DMG cells (PDGFB+, H3.3K27M, p53-/-). A clinical RT dose of 39 Gy in 13 fractions (39 Gy/13fx) was delivered using the Small Animal Radiation Research Platform (SARRP) or XRAD-320 irradiator. FUS was administered via a 0.5 MHz transducer, with BBBO and tumor volume monitored by magnetic resonance imaging (MRI).

RESULTS

FUS-mediated BBBO did not affect cardiorespiratory rate, motor function, or tissue integrity in non-tumor bearing mice receiving RT. Tumor-bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy/13fx offered local control, though disease progression occurred 3-4 weeks post-RT.

CONCLUSION

Repeated FUS-mediated BBBO is safe and feasible concurrent with RT. In our syngeneic DMG murine model, progression occurs, serving as an ideal model for future combination testing with RT and FUS-mediated drug delivery.

A decade of treating brain stem gliomas: Single institutional experience

INTRODUCTION

Brainstem is a rare yet challenging site for primary brain tumors. We present the patient characteristics, treatment-related details, and survival outcomes of patients with brain stem gliomas treated over a decade, from August 2010 to July 2022, at a tertiary care center in northern India.

MATERIALS AND METHODS

Twenty-seven patients of brainstem gliomas were treated in our hospital from August 2010 to July 2022. All of these patients were treated with radiation therapy based on a radiological diagnosis only. Data were collected and analyzed from patient registration, treatment, and follow-up records.

RESULTS

Of the 27 patients, 18 were male and 9 were female. Fourteen patients (51.85%) were in the pediatric age group (<12 years). The most common symptom at onset was hemiparesis, seen in 62.96%. The majority of the patients (24; 88.88%) had pontine involvement at the time of treatment. Overall survival at a minimum 2-year follow-up post-treatment was 22.22% in the entire cohort. Age, sex, or size of tumor at presentation was not seen to have any significant impact on survival of patients.

CONCLUSION

With the advancement in surgical techniques and molecular analysis of brain tumors, there is likely to be a change in the management of brainstem gliomas; however, radiation therapy has been used for the management of these tumors for decades now. Radiation therapy continues to show rapid and significant radiological and clinical improvement in the majority of such patients, and it would continue to play an important part in multi-modality management.

Bench-to-bedside investigations of H3 K27-altered diffuse midline glioma: drug targets and potential pharmacotherapies

INTRODUCTION

H3 K27-altered diffuse midline glioma (DMG) is the most common malignant brainstem tumor in the pediatric population. Despite enormous preclinical and clinical efforts, the prognosis remains dismal, with fewer than 10% of patients surviving for two years after diagnosis. Fractionated radiation remains the only standard treatment options for DMG. Developing novel treatments and therapeutic delivery methods is critical to improving outcomes in this devastating disease.

AREAS COVERED

This review addresses recent advances in molecularly targeted pharmacotherapy and immunotherapy in DMG. The clinical presentation, diagnostic workup, unique pathological challenges, and current clinical trials are highlighted throughout.

EXPERT OPINION

Promising pharmacotherapies targeting various components of DMG pathology and the application of immunotherapies have the potential to improve patient outcomes. However, novel approaches are needed to truly revolutionize treatment for this tumor. First, combinational therapy should be employed, as DMG can develop resistance to single-agent approaches and many therapies are susceptible to rapid clearance from the brain. Second, drug-tumor residence time, i.e. the time for which a therapeutic is present at efficacious concentrations within the tumor, must be maximized to facilitate a durable treatment response. Engineering extended drug delivery methods with minimal off-tumor toxicity should be a focus of future studies.

The Korean Society for Neuro-Oncology (KSNO) Guideline for Adult Diffuse Midline Glioma: Version 2021.1

BACKGROUND

There have been no guidelines for the management of adult patients with diffuse midline glioma (DMG), H3K27M-mutant in Korea since the 2016 revised WHO classification newly defined this disease entity. Thus, the Korean Society for Neuro-Oncology (KSNO), a multidisciplinary academic society, had begun preparing guidelines for DMG since 2019.

METHODS

The Working Group was composed of 27 multidisciplinary medical experts in Korea. References were identified through searches of PubMed, MEDLINE, EMBASE, and Cochrane CENTRAL using specific and sensitive keywords as well as combinations of keywords. As 'diffuse midline glioma' was recently defined, and there was no international guideline, trials and guidelines of 'diffuse intrinsic pontine glioma' or 'brain stem glioma' were thoroughly reviewed first.

RESULTS

The core contents are as follows. The DMG can be diagnosed when all of the following three criteria are satisfied: the presence of the H3K27M mutation, midline location, and infiltrating feature. Without identification of H3K27M mutation by diagnostic biopsy, DMG cannot be diagnosed. For the primary treatment, maximal safe resection should be considered for tumors when feasible. Radiotherapy is the primary option for tumors in case the total resection is not possible. A total dose of 54 Gy to 60 Gy with conventional fractionation prescribed at 1-2 cm plus gross tumor volume is recommended. Although no chemotherapy has proven to be effective in DMG, concurrent chemoradiotherapy (± maintenance chemotherapy) with temozolomide following WHO grade IV glioblastoma's protocol is recommended.

CONCLUSION

The detection of H3K27M mutation is the most important diagnostic criteria for DMG. Combination of surgery (if amenable to surgery), radiotherapy, and chemotherapy based on comprehensive multidisciplinary discussion can be considered as the treatment options for DMG.

Hypofractionated radiotherapy versus conventional radiotherapy for diffuse intrinsic pontine glioma: A systematic review and meta-analysis

BACKGROUND

The standard treatment for diffuse intrinsic pontine glioma (DIPG) is radiotherapy, although conventional fractionated radiotherapy (CFRT) may not be in the best interest of the patient. Instead, hypofractionated radiotherapy (HFRT) may shorten the treatment period and reduce related costs for this treatment, which is typically palliative in nature.

METHODS

This systematic review and meta-analysis evaluated survival outcomes among patients who received HFRT or CFRT for DIPG. The PubMed, Medline, EMBASE, Cochrane Central Register, and Scopus databases were searched to identify relevant studies. Overall survival was the primary outcome of interest and progression-free survival was the secondary outcome of interest.

RESULTS

The search identified a total of 2376 reports, although only 4 reports were ultimately included in the meta-analysis. The studies included 88 patients who underwent HFRT and 96 patients who underwent CFRT. Relative to CFRT, HFRT provided comparable outcomes in terms of overall survival (hazard ratio [HR]: 1.07, 95% confidence interval [CI]: 0.77-1.47) and progression-free survival (HR: 1.04, 95% CI: 0.75-1.45).

CONCLUSIONS

The results of this meta-analysis suggest that CFRT and HFRT provide similar survival outcomes for patients with DIPG.

A New Treatment Opportunity for DIPG and Diffuse Midline Gliomas: 5-ALA Augmented Irradiation, the 5aai Regimen

Prognosis for diffuse intrinsic pontine glioma (DIPG) and generally for diffuse midline gliomas (DMG) has only marginally improved over the last ~40 years despite dozens of chemotherapy and other therapeutic trials. The prognosis remains invariably fatal. We present here the rationale for a planned study of adding 5-aminolevulinic acid (5-ALA) to the current irradiation of DIPG or DMG: the 5aai regimen. In a series of recent papers, oral 5-ALA was shown to enhance standard therapeutic ionizing irradiation. 5-ALA is currently used in glioblastoma surgery to enable demarcation of overt tumor margins by virtue of selective uptake of 5-ALA by neoplastic cells and selective conversion to protoporphyrin IX (PpIX), which fluoresces after excitation by 410 nm (blue) light. 5-ALA is also useful in treating glioblastomas by virtue of PpIX's transfer of energy to O₂ molecules, producing a singlet oxygen that in turn oxidizes intracellular DNA, lipids, and proteins, resulting in selective malignant cell cytotoxicity. This is called photodynamic treatment (PDT). Shallow penetration of light required for PpIX excitation and resultant energy transfer to O₂ and cytotoxicity results in the inaccessibility of central structures like the pons or thalamus to sufficient light. The recent demonstration that keV and MeV photons can also excite PpIX and generate singlet O₂ allows for reconsideration of 5-ALA PDT for treating DMG and DIPG. 5-ALA has an eminently benign side effect profile in adults and children. A pilot study in DIPG/DMG of slow uptitration of 5-ALA prior to each standard irradiation session-the 5aai regimen-is warranted.