Improved survival and intracranial tumor control of EGFR-mutated NSCLC patients with newly developed brain metastases following stereotactic radiosurgery and EGFR-TKI: a large retrospective cohort study and meta-analyses

Prioritizing Radiation and Targeted Systemic Therapies in Patients with Resected Brain Metastases from Lung Cancer Primaries with Targetable Mutations: A Report from a Multi-Site Single Institution

Background/Objectives: Brain metastases (BrMs) are a common complication of non-small cell lung cancer (NSCLC), present in up to 50% of patients. While the treatment of BrMs requires a multidisciplinary approach with surgery, radiotherapy (RT), and systemic therapy, the advances in molecular sequencing have improved outcomes in patients with targetable mutations. With a push towards the molecular characterization of cancers, we evaluated the outcomes by treatment modality at our institution with respect to prioritizing RT and targeted therapies. Methods: We identified the patients with NSCLC BrMs treated with surgical resection. The primary endpoints were in-brain freedom from progression (FFP) and overall survival (OS). The secondary endpoint included index lesion recurrence. The tumor molecular profiles were reviewed. The outcomes were evaluated by treatment modality: surgery followed by adjuvant RT and/or adjuvant systemic therapy. Results: In total, 155/272 (57%) patients who received adjuvant therapy with adequate follow-up were included in this analysis. The patients treated with combination therapy vs. monotherapy had a median FFP time of 10.72 months vs. 5.38 months, respectively (p = 0.072). The patients of Hispanic/Latino vs. non-Hispanic/Latino descent had a statistically significant worse OS of 12.75 months vs. 53.15 months, respectively (p = 0.015). The patients who received multimodality therapy had a trend towards a reduction in index lesion recurrences (χ2 test, p = 0.063) with a statistically significant improvement in the patients receiving immunotherapy (χ2 test, p = 0.0018). Conclusions: We found that systemic therapy combined with RT may have an increasing role in delaying the time to progression; however, there was no statistically significant relationship between OS and treatment modality.

Long-term geometric quality assurance of radiation focal point and cone-beam computed tomography for Gamma Knife radiosurgery system

To investigate the geometric accuracy of the radiation focal point (RFP) and cone-beam computed tomography (CBCT) over long-term periods for the ICON Leksell Gamma Knife radiosurgery system. This phantom study utilized the ICON quality assurance tool plus, and the phantom was manually set on the patient position system before the implementation of treatment for patients. The deviation of the RFP position from the unit center point (UCP) and the positions of the four ball bearings (BBs) in the CBCT from the reference position were automatically analyzed. During 544 days, a total of 269 analyses were performed on different days. The mean ± standard deviation (SD) of the deviation between measured RFP and UCP was 0.01 ± 0.03, 0.01 ± 0.03, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively. The deviations with offset values after the cobalt-60 source replacement (0.00 ± 0.03, -0.01 ± 0.01, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively) were significantly (p = 0.001) smaller than those before the replacement (0.02 ± 0.03, 0.02 ± 0.01, and -0.02 ± 0.01 mm in the X, Y, and Z directions, respectively). The overall mean ± SD of four BBs was -0.03 ± 0.03, -0.01 ± 0.05, and 0.01 ± 0.03 mm in the X, Y, and Z directions, respectively. Geometric positional accuracy was ensured to be within 0.1 mm on most days over a long-term period of more than 500 days.

Distinct Progression and Efficacy of First-Line Osimertinib Treatment According to Mutation Subtypes in Metastatic NSCLC Harboring EGFR Mutations

Introduction

Osimertinib (OSI), a third-generation EGFR tyrosine kinase inhibitor, is the standard treatment for patients with naive EGFR-mutant NSCLC. Nevertheless, information on how the mutation subtype affects disease progression after the failure of OSI treatment is scarce.

Methods

We retrospectively reviewed patients with EGFR-mutant NSCLC who received OSI as a first-line treatment between April 2015 and December 2021.

Results

This study included 229 patients. The objective response rate was 71%, with intracranial and extracranial response rates of 71% and 90%, respectively. The median progression-free survival was 23.3 mo (95% confidence interval [CI]: 19.6-26.7), and the median overall survival was 33.7 mo (95% CI: 31.3-58.6). Multivariate analysis revealed that the EGFR exon 21 L858R point mutation (L858R) (hazard ratio [HR] = 1.56, 95% CI: 1.04-2.34, p = 0.0328) and liver metastasis (HR = 2.63, 95% CI: 1.53-4.49, p = 0.0004) were significant predictors of progression-free survival in OSI treatment. The concomitant disease progression involving the central nervous system metastasis was significantly more common in patients with L858R (p = 0.048), whereas concomitant disease progression involving primary lesions was significantly more common in patients with exon 19 deletion mutation (p = 0.01). In addition, the probability of disease progression over time was higher for L858R compared with that for exon 19 deletion mutation, in patients with central nervous system metastasis (log-rank test, p = 0.027).

Conclusions

The mutation subtype had an impact not only on the clinical outcome of the first-line OSI treatment but also on progression patterns after OSI treatment in patients with NSCLC harboring EGFR mutations.