Therapeutic effect of osimertinib plus cranial radiotherapy compared to osimertinib alone in NSCLC patients with EGFR-activating mutations and brain metastases: a retrospective study

Background The study aimed to compare the efficacy of osimertinib plus cranial radiotherapy (RT) with osimertinib alone in advanced non-small-cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) mutations and brain metastases (BMs). Methods The clinical data of advanced NSCLC patients with BMs who received osimertinib were retrospectively collected. The patients were assigned to one of the two groups according to the therapeutic modality used: the osimertinib monotherapy group or the osimertinib plus RT group. Results This was a retrospective study and 61 patients were included from December 2015 to August 2020. Forty patients received osimertinib monotherapy, and twenty-one patients received osimertinib plus RT. Radiotherapy included whole-brain radiation therapy (WBRT, n = 14), WBRT with simultaneous integrated boost (WBRT-SIB, n = 5) and stereotactic radiosurgery (SRS, n = 2). The median number of prior systemic therapies in the two groups was one. Intracranial and systemic ORR and DCR were not significantly different between the two groups. No difference in iPFS was observed between the two groups (median iPFS: 16.67 vs. 13.50 months, P = 0.836). The median OS was 29.20 months in the osimertinib plus RT group compared with 26.13 months in the osimertinib group (HR = 0.895, P = 0.826). In the L858R mutational subgroup of 31 patients, the osimertinib plus RT group had a longer OS (P = 0.046). In the exon 19 deletion mutational subgroup of 30 patients, OS in the osimertinib alone group was longer than that in the osimertinib plus RT group (P = 0.011). The incidence of any-grade adverse events was not significantly different between the osimertinib plus RT group and the osimertinib alone group (47.6% vs. 32.5%, P = 0.762). However, six patients (28.5%) experienced leukoencephalopathy in the osimertinib plus RT group, and 50% (3/6) of the leukoencephalopathy was greater than or equal to grade 3. Conclusion The therapeutic effect of osimertinib with RT was similar to that of osimertinib alone in EGFR-positive NSCLC patients with BM. However, for patients with the L858R mutation, osimertinib plus RT could provide more benefit than osimertinib alone.

NCMP-16. MANAGEMENT AND LONG-TERM OUTCOMES OF PATIENTS WITH RECURRENT STROKE-LIKE EPISODES AFTER CRANIAL RADIOTHERAPY

Stroke-Like Migraine Attacks after Radiation Therapy (SMART) is a descriptive clinical entity consisting of transient hemispheric dysfunction. We were interested in pragmatic management patterns for patients with Recurrent Stroke-Like Episodes (R-SLE) of transient negative neurologic symptoms after cranial radiotherapy (RT) to define optimal management strategy and assess long-term outcomes. We conducted a retrospective review of all patients with recurrent negative neurologic symptoms after cranial RT who were treated at Mayo Clinic (Rochester), with follow-up extending until February 2021. Descriptive statistics and Chi-Square analysis was performed to assess for differences between patients with clinical cessation of symptoms, death, progressive encephalopathy and therapeutic class, patient and primary treatment characteristics (i.e. whole brain RT). We identified 27 patients with R-SLE after RT. 25 patients were included in analyses. Median age at diagnosis was 28.7 years (3.0-65.8 years, SD: 15.0 years). Median time from RT to symptom onset was 14.6 years (3.3-30.5 years, SD: 8.9 years). The most common presentations included hemiparesis (55.6%), hemisensory loss (22.2%), transient visual field loss (33.3%), encephalopathy (18.5%), and aphasia (22.2%). Antiseizure medications were most used for management of R-SLE (92%) followed by anti-platelets (68%), verapamil (52%), statins (48%), glucocorticoids (24%), antivirals (20%), and ACE inhibitors/angiotensin receptor blockers (16%). Beta blockers were not used. Verapamil use was frequently associated with clinical cessation of recurrent events with cessation being achieved in 64.7% of patients on verapamil versus 35.3% not on verapamil (p=0.0638). Other medical interventions did not approach clinical or statistical significance. Progressive encephalopathy was more common in patients without clinical cessation (87.5% vs. 23.5%, p=0.0026). All patients who died at last follow-up had progressive encephalopathy. We found cessation of recurrent negative neurologic symptoms after cranial RT in most patients. Verapamil use was associated with clinical cessation. Progressive encephalopathy was more common in patients without clinical cessation of recurrent events.

Active Fraction Combination From Liuwei Dihuang Decoction Improves Adult Hippocampal Neurogenesis and Neurogenic Microenvironment in Cranially Irradiated Mice

Background: Cranial radiotherapy is clinically used in the treatment of brain tumours; however, the consequent cognitive and emotional dysfunctions seriously impair the life quality of patients. LW-AFC, an active fraction combination extracted from classical traditional Chinese medicine prescription Liuwei Dihuang decoction, can improve cognitive and emotional dysfunctions in many animal models; however, the protective effect of LW-AFC on cranial irradiation–induced cognitive and emotional dysfunctions has not been reported. Recent studies indicate that impairment of adult hippocampal neurogenesis (AHN) and alterations of the neurogenic microenvironment in the hippocampus constitute critical factors in cognitive and emotional dysfunctions following cranial irradiation. Here, our research further investigated the potential protective effects and mechanisms of LW-AFC on cranial irradiation–induced cognitive and emotional dysfunctions in mice.Methods: LW-AFC (1.6 g/kg) was intragastrically administered to mice for 14 days before cranial irradiation (7 Gy γ-ray). AHN was examined by quantifying the number of proliferative neural stem cells and immature neurons in the dorsal and ventral hippocampus. The contextual fear conditioning test, open field test, and tail suspension test were used to assess cognitive and emotional functions in mice. To detect the change of the neurogenic microenvironment, colorimetry and multiplex bead analysis were performed to measure the level of oxidative stress, neurotrophic and growth factors, and inflammation in the hippocampus.Results: LW-AFC exerted beneficial effects on the contextual fear memory, anxiety behaviour, and depression behaviour in irradiated mice. Moreover, LW-AFC increased the number of proliferative neural stem cells and immature neurons in the dorsal hippocampus, displaying a regional specificity of neurogenic response. For the neurogenic microenvironment, LW-AFC significantly increased the contents of superoxide dismutase, glutathione peroxidase, glutathione, and catalase and decreased the content of malondialdehyde in the hippocampus of irradiated mice, accompanied by the increase in brain-derived neurotrophic factor, insulin-like growth factor-1, and interleukin-4 content. Together, LW-AFC improved cognitive and emotional dysfunctions, promoted AHN preferentially in the dorsal hippocampus, and ameliorated disturbance in the neurogenic microenvironment in irradiated mice.Conclusion: LW-AFC ameliorates cranial irradiation–induced cognitive and emotional dysfunctions, and the underlying mechanisms are mediated by promoting AHN in the dorsal hippocampus and improving the neurogenic microenvironment. LW-AFC might be a promising therapeutic agent to treat cognitive and emotional dysfunctions in patients receiving cranial radiotherapy.

P05.01 Prospective validation trial of magnetic resonance imaging based Contrast Clearance Analysis (CCA) to differentiate between pseudoprogression/radiation necrosis and progressive disease following cranial radiotherapy

BACKGROUND Pseudoprogression (PsP) or radiation necrosis (RN) may frequently occur after cranial radiotherapy and show a similar imaging pattern compared to progressive disease (PD). Even for experienced neuroradiologists, it remains challenging to distinguish between these clinically relevant disease states. We aimed to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) based Contrast Clearance Analysis (CCA) in this clinical setting. MATERIAL AND METHODS Patients with equivocal imaging findings after cranial radiotherapy were consecutively included into this monocentric prospective study. Assuming a true accuracy of 90% and setting the significance level to 0.05, N=33 patients are required to show that accuracy is larger than 70% with a power of 80% using a one-sided binomial test. CCA was performed by subtraction of imaging features in late vs early T1-weighted sequences after contrast-agent application. Two experienced neuroradiologists evaluated CCA with respect to PsP/RN and PD being blinded for FET PET and histological findings; histopathological diagnosis was based on stereotactic biopsy or resection for space-occupying processes. The radiological assessment was compared with the histopathological results, and its accuracy was calculated statistically. RESULTS Thirty-three patients were included; sixteen (48.5%) were treated because of a primary brain tumors, and 17 (51.1%) with brain metastases. In one patient, CCA was technically infeasible. The accuracy of CCA in predicting the histological result was 0.84 (95% CI 0.67–0.95; one-sided p=0.05; N=32). An accuracy of 0.85 (95% CI 0.68–0.95; one-sided p=0.04) would have been obtained in case of a correct classification in the non-analyzable case. Sensitivity and specificity of CCA were 0.93 (95%-CI 0.66–1.00) and 0.78 (95% CI 0.52–0.94), respectively. The accuracy in metastases patients was 0.94 (95% CI 0.71 - 1.00) and non-significantly higher compared to primary brain tumor patients with accuracy of 0.73 (95% CI 0.45 - 0.92), p=0.16. CONCLUSION In this study, CCA was a highly accurate, easy and helpful method for distinguishing PsP or RN from PD after cranial radiotherapy, especially in brain metastases patients after radiosurgical treatment.

Are radiation-induced cavernomas clinically relevant findings? Results from long-term follow-up with brain magnetic resonance imaging of childhood cancer survivors

Introduction Radiation-induced cavernomas (RIC) after cranial radiotherapy have an unknown risk of hemorrhage. Zabramski magnetic resonance imaging (MRI) classification is touted as being able to indicate non-radiation-induced cavernomas hemorrhage risk. The aim of our study was to assess the hemorrhage risk of RIC during long-term follow-up of childhood cancer survivors based on brain MRI examinations. Patients and methods We analyzed retrospectively long-term follow-up data of 36 childhood cancer survivors after initial diagnosis with acute leukemia (n = 18) or brain tumor (n = 18), all treated with cranial radiotherapy. Detected RIC in long-term follow-up brain MRI (1.5 or 3 Tesla) were classified following the Zabramski MRI classification and were categorized into “high” (Zabramski type I, II or V) or “low” (type III or IV) risk of hemorrhage. Results 18 patients (50%) showed RIC with a significant relation to the original tumor entity (p = 0.023) and the cumulative radiation dose to the brain (p = 0.016): all 9 childhood cancer survivors diagnosed with medulloblastoma developed RIC. We classified RIC in only 3/36 childhood cancer survivors (8%) (1 patient with acute lymphoblastic leukemia [Zabramski type II] and 2 patients with medulloblastoma [type I and type II]) as high risk for hemorrhage, the remaining RIC were classified as Zabramski type IV with low risk for hemorrhage. None of the childhood cancer survivors with RIC showed symptomatic hemorrhages. Conclusions RIC are common late effects in childhood cancer survivors treated with cranial radiotherapy affecting half of these patients. However, only a few RIC (occurring in 8% of all reviewed childhood cancer survivors) were classified as high risk for hemorrhage and none of the childhood cancer survivors with RIC developed symptomatic hemorrhages. Thus, we conclude that RIC are low-risk findings in brain MRI and the course is mainly benign.