Intensity-modulated radiation to spare neural stem cells in brain tumors: A computational platform for evaluation of physical and biological dose metrics

Background: Neurocognitive effects following whole-brain and partial-brain irradiation can cause considerable morbidity. Sparing of neural stem cells (NSCs) is proposed as an avenue for reducing the long-term radiation-induced defects in learning, memory, and intelligence. We performed an analytical study to spare the NSC from partial-brain irradiation by intensity-modulated radiotherapy (IMRT). Objective: The aim of this study is to achieve maximal sparing of NSC during irradiation of brain tumors using biologically equivalent dose (BED) for all plans. The consequent clinical benefit will possibly be in terms of acute effects on stem cells and delayed neurologic sequelae to brain. A tool to modulate various physical and biological dose metrics has been used to study the optimization of radiation therapy for brain tumors with constraints imposed on total radiation to NSC. Materials and Methods: A total of 10 successive patients of grade III and IV gliomas of brain, who underwent total or near total excision of brain tumors, were included in the study. Patients underwent computed tomography and magnetic resonance imaging fusion for contouring. Computational codes used to analyze the efficacy of the plan are quality of coverage, homogeneity index, and conformity index. Wide range of radiosensitivity parameters were evaluated by using equivalent uniform dose and tumor control probability (TCP) to predict tumor control with and without sparing of NSC. Results: The physical and biological dose metrics were modulated by fitting standard deviation of 0.3% for all plans. The maximum NSC sparing was achieved in IMRT plans with constraints applied to local TCP. Similarly, for BED of plans with and without constraints, the estimated mean reduction in acute complications of NSC achieved was 12.23% (range, 4.27-28.33%). The estimated mean reduction in BED for late complications of late-reacting brain tissue is 14.69% (range, 7.39-33.56%)

Intensity-modulated radiation to spare neural stem cells in brain tumors: A computational platform for evaluation of physical and biological dose metrics

Background: Neurocognitive effects following whole-brain and partial-brain irradiation can cause considerable morbidity. Sparing of neural stem cells (NSCs) is proposed as an avenue for reducing the long-term radiation-induced defects in learning, memory, and intelligence. We performed an analytical study to spare the NSC from partial-brain irradiation by intensity-modulated radiotherapy (IMRT). Objective: The aim of this study is to achieve maximal sparing of NSC during irradiation of brain tumors using biologically equivalent dose (BED) for all plans. The consequent clinical benefit will possibly be in terms of acute effects on stem cells and delayed neurologic sequelae to brain. A tool to modulate various physical and biological dose metrics has been used to study the optimization of radiation therapy for brain tumors with constraints imposed on total radiation to NSC. Materials and Methods: A total of 10 successive patients of grade III and IV gliomas of brain, who underwent total or near total excision of brain tumors, were included in the study. Patients underwent computed tomography and magnetic resonance imaging fusion for contouring. Computational codes used to analyze the efficacy of the plan are quality of coverage, homogeneity index, and conformity index. Wide range of radiosensitivity parameters were evaluated by using equivalent uniform dose and tumor control probability (TCP) to predict tumor control with and without sparing of NSC. Results: The physical and biological dose metrics were modulated by fitting standard deviation of 0.3% for all plans. The maximum NSC sparing was achieved in IMRT plans with constraints applied to local TCP. Similarly, for BED of plans with and without constraints, the estimated mean reduction in acute complications of NSC achieved was 12.23% (range, 4.27-28.33%). The estimated mean reduction in BED for late complications of late-reacting brain tissue is 14.69% (range, 7.39-33.56%)

RE-OPEN: Randomised trial of biosimilar TNK versus TPA during endovascular therapy for acute ischaemic stroke due to large vessel occlusions

Rationale Rapid and timely treatment with intravenous thrombolysis and endovascular treatment (EVT) in patients with acute ischaemic stroke (AIS) and large vessel occlusion (LVO) significantly improves patient outcomes. Bridging therapy is the current standard of care in these patients. However, an incompletely answered question is whether one thrombolytic agent is better than another during bridging therapy.Aim The current study aims to understand if one thrombolytic agent is superior to the other during bridging therapy in the treatment of AIS and LVO.Sample size estimates Using 80% power and an alpha error of 5 %, presuming a 10% drop out rate, a total of 372 patients will be recruited for the study.Methods and design This study is a prospective, randomised, multicentre, open-label trial with blinded outcome analysis design.Study outcomes The primary outcomes include proportion of patients who will be independent at 3 months (modified Rankin score (mRS) ≤2 as good outcome) and proportion of patients who achieve recanalisation modified thrombolysis in cerebral infarction grade 2b/3 at first angiography run at the end of EVT. Secondary outcomes include proportion of patients with early neurological improvement, rate of symptomatic intracerebral haemorrhage (ICH), rate of any ICH, rate of any systemic major or minor bleeding and duration of hospital stay. Safety outcomes include any intracranial bleeding or symptomatic ICH.Discussion This trial is envisioned to confirm the theoretical advantages and increase the strength and quality of evidence for use of tenecteplase (TNK) in practice. Also, it will help to generate data on the efficacy and safety of biosimilar TNK.Trial registration number CTRI/2022/01/039473

STENOSIS: Long-term single versus dual antiplatelet therapy in patients with ischaemic stroke due to intracranial atherosclerotic disease – a randomised trial

Rationale Intracranial atherosclerotic disease (ICAD) is a pathological process that causes progressive stenosis and cerebral hypoperfusion, leading to stroke occurrence and recurrence around the world. The exact duration of dual antiplatelet therapy (DAPT) for ICAD is unclear in view of long-term risk of bleeding complications.Aim The current study aims to study the efficacy and safety of long-term DAPT (up to 12 months) in patients with ICAD.Sample size Using 80% power and an alpha error of 5 %, presuming a 10%–15% drop-out rate, a total of 2200 patients will be recruited for the study.Methodology This is a prospective, randomised, double-blind, placebo controlled trial.Study outcomes The primary outcomes include recurrent ischaemic stroke (IS) or transient ischaemic attack and any intracranial haemorrhage (ICH), major or minor systemic bleeding at the end of 12 months. Secondary outcomes include composite of any stroke, myocardial infarction or death at the end of 12 months. The safety outcomes include any ICH, major or minor bleeding as defined using GUSTO (Global Use of Streptokinase and tPA for occluded Coronary Arteries) classification at the end of 12 months and 1 month after completion of the drug treatment phase.Discussion The study will provide level I evidence on the duration of DAPT among patients with IS due to ICAD of more than or equal to 50%