Optimal systemic treatment and real-world clinical application of ctDNA in patients with metastatic HER2-mutant lung cancer.

INTRODUCTION: No definitive answers currently exist regarding optimal first-line therapy for HER2-mutant NSCLC. Access to rapid tissue sequencing is a major barrier to precision drug development in the first-line setting. ctDNA analysis has the potential to overcome these obstacles and guide treatment. METHODS: We retrospectively analyzed patients with metastatic HER2-mutant NSCLC who underwent prospective clinical ctDNA sequencing and received systemic therapy at Memorial Sloan Kettering Cancer Center (MSK) from January 2016 to September 2022. HER2 mutations were identified by next-generation sequencing through MSK-IMPACT, MSK-ACCESS or Resolution ctDx LungTM assay. Primary endpoints were time to the next treatment (TTNT) and overall survival (OS). RESULTS: Sixty-three patients were included in the primary analysis. Chemoimmunotherapy (33/63, 52.4 %) was the predominant first-line treatment with a median TTNT of 5.1 months (95 %CI 4.1 - 6.1) whereas 55.0 % (22/40) of patients who received second-line T-DXd obtained a median TTNT of 9.2 m (95 % CI, 0-22.2). Plasma ctDNA was tested before first-line therapy in 40 patients with a median OS of 28.0 months (95 % CI 21-34), in whom 31 patients (78.0 %) had detectable ctDNA. HER2 mutations were detected on ctDNA with a median turnaround time of 13 days, occasionally co-occurred with EGFR and MET alterations and were tracked longitudinally correlating with treatment response. Patients with detectable baseline ctDNA had significantly shorter OS (hazard ratio (HR), 5.25; 95 % CI, 1.2-23.9; p = 0.019). CONCLUSION: Chemoimmunotherapy remains a major treatment option for metastatic HER2-mutant NSCLC. ctDNA can rapidly detect HER2 and co-mutations, and it has the potential to guide and monitor optimal first-line therapy. As a negative prognostic biomarker, detectable ctDNA at baseline would need to be taken into account for patient selection in future studies.

Clinical Outcomes and Targeted Genomic Analysis of Renal Cell Carcinoma Brain Metastases Treated with Stereotactic Radiosurgery.

BACKGROUND: Molecular profiles of renal cell carcinoma (RCC) brain metastases (BMs) are not well characterized. Effective management with locoregional therapies, including stereotactic radiosurgery (SRS), is critical as systemic therapy advancements have improved overall survival (OS). OBJECTIVE: To identify clinicogenomic features of RCC BMs treated with SRS in a large patient cohort. DESIGN, SETTING, AND PARTICIPANTS: A single-institution retrospective analysis was conducted of all RCC BM patients treated with SRS from January 1, 2010 to March 31, 2021. INTERVENTION: SRS for RCC BMs. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Next-generation sequencing was performed to identify gene alterations more prevalent in BM patients. Clinical factors and genes altered in ≥10% of samples were assessed per patient using Cox proportional hazards models and per individual BM using clustered competing risks regression with competing risk of death. RESULTS AND LIMITATIONS: Ninety-one RCC BM patients underwent SRS to 212 BMs, with a median follow-up of 38.8 mo for patients who survived. The median intracranial progression-free survival and OS were 7.8 (interquartile range [IQR] 5.7-11) and 21 (IQR 16-32) mo, respectively. Durable local control of 83% was achieved at 12 mo after SRS, and 59% of lesions initially meeting the radiographic criteria for progression at 3-mo evaluation would be considered to represent pseudoprogression at 6-mo evaluation. A comparison of genomic alterations at both the gene and the pathway level for BM+ patients compared with BM- patients revealed phosphoinositide 3-kinase (PI3K) pathway alterations to be more prevalent in BM+ patients (43% vs 16%, p = 0.001, q = 0.01), with the majority being PTEN alterations (17% vs 2.7%, p = 0.003, q = 0.041). CONCLUSIONS: To our knowledge, this is the largest study investigating genomic profiles of RCC BMs and the only such study with annotated intracranial outcomes. SRS provides durable in-field local control of BMs. Recognizing post-SRS pseudoprogression is crucial to ensure appropriate management. The incidence of PI3K pathway alterations is more prevalent in BM+ patients than in BM- patients and warrants further investigation in a prospective setting. PATIENT SUMMARY: We examined the outcomes of radiotherapy for the treatment of brain metastases in kidney cancer patients at a single large referral center. We found that radiation provides good control of brain tumors, and certain genetic mutations may be found more commonly in patients with brain metastasis.

Clinicogenomic predictors of survival and intracranial progression after stereotactic radiosurgery for colorectal cancer brain metastases.

OBJECTIVE: Brain metastases (BM) from colorectal cancer (CRC) are associated with dismal prognosis. When BM-directed therapy is considered, better methods are needed to identify patients at risk of poor oncological outcomes in order to optimize patient selection for closer surveillance or escalated therapy. The authors sought to identify clinicogenomic predictors of survival and intracranial disease progression after CRC BM have been treated with stereotactic radiosurgery (SRS). METHODS: Patients with newly diagnosed CRC BM treated with SRS between 2009 and 2022 who had next-generation genomic sequencing data available were included. Frameless SRS was delivered in 1-5 fractions, alone or after neurosurgical resection. Outcomes included overall survival (OS) and intracranial progression (IP), evaluated per patient treated with SRS, and local progression (LP), evaluated per BM. Associations between baseline clinicogenomic features and outcomes were evaluated with Cox regression and competing risk regression, with death as a competing risk. RESULTS: This analysis included 123 patients with 299 BM. At BM diagnosis, 111 patients (90%) had progressive extracranial disease, and 79 patients (64%) had ≥ 3 sites of extracranial metastasis. The median (IQR) number of BM was 2 (1-3) per patient. The median (IQR) biologically effective dose (BED) was 51.3 (51.3-65.1) Gy, corresponding to a prescription of 27 Gy in 3 fractions. OS, IP, and LP estimates at 1 year after SRS were 36%, 55%, and 12%, respectively. OS was independently associated with progressive extracranial disease (HR 4.26, 95% CI 1.63-11.2, p = 0.003) and ≥ 3 extracranial metastatic sites (HR 1.84, 95% CI 1.12-3.01, p = 0.02). LP was less likely when BM received BED ≥ 51.3 Gy (HR 0.24, 95% CI 0.07-0.78, p = 0.02), independent of BM diameter (HR 1.21/cm, 95% CI 0.8-1.84, p = 0.4). IP was independently associated with genomic alterations; TP53 driver alterations were associated with higher risk of IP (HR 2.71, 95% CI 1.26-5.79, p = 0.01), whereas MYC pathway alterations were associated with lower risk (HR 0.15, 95% CI 0.03-0.68, p = 0.01). CONCLUSIONS: The authors identified clinicogenomic features associated with adverse outcomes after SRS for CRC BM. Progressive and extensive extracranial metastases predicted worse OS. Insufficient SRS doses predicted greater risk of LP. Wild-type TP53 and alterations in the MYC pathway were independently associated with lower risk of IP. Patients at high risk of IP may be considered for closer surveillance or escalated therapy.

Tyrosine Kinase Inhibitors With and Without Up-Front Stereotactic Radiosurgery for Brain Metastases From EGFR and ALK Oncogene-Driven Non-Small Cell Lung Cancer (TURBO-NSCLC).

PURPOSE: Newer-generation tyrosine kinase inhibitors (TKIs) for non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements have demonstrated high CNS activity. The optimal use of up-front stereotactic radiosurgery (SRS) for brain metastases (BM) in patients eligible for CNS-penetrant TKIs is controversial, and data to guide patient management are limited. MATERIALS AND METHODS: Data on TKI-naïve patients with EGFR- and ALK-driven NSCLC with BM treated with CNS-penetrant TKIs with and without up-front SRS were retrospectively collected from seven academic centers in the United States. Time-to-CNS progression and overall survival (OS) were analyzed, with multivariable adjustment in Fine & Gray and Cox proportional hazards models for clinically relevant factors. RESULTS: From 2013 to 2022, 317 patients were identified (200 TKI-only and 117 TKI + SRS). Two hundred fifty (79%) and 61 (19%) patients received osimertinib and alectinib, respectively. Patients receiving TKI + SRS were more likely to have BM ≥1 cm (P < .001) and neurologic symptoms (P < .001) at presentation. Median OS was similar between the TKI and TKI + SRS groups (median 41 v 40 months, respectively; P = .5). On multivariable analysis, TKI + SRS was associated with a significant improvement in time-to-CNS progression (hazard ratio [HR], 0.63 [95% CI, 0.42 to 0.96]; P = .033). Local CNS control was significantly improved with TKI + SRS (HR, 0.30 [95% CI, 0.16 to 0.55]; P < .001), whereas no significant differences were observed in distant CNS control. Subgroup analyses demonstrated a greater benefit from TKI + SRS in patients with BM ≥1 cm in diameter for time-to-CNS progression and CNS progression-free survival. CONCLUSION: The addition of up-front SRS to CNS-penetrant TKI improved time-to-CNS progression and local CNS control, but not OS, in patients with BM from EGFR- and ALK-driven NSCLC. Patients with larger BM (≥1 cm) may benefit the most from up-front SRS.

Clinical validation of a cell-free DNA fragmentome assay for augmentation of lung cancer early detection.

Lung cancer screening via annual low-dose computed tomography (LDCT) has poor adoption. We conducted a prospective case-control study among 958 individuals eligible for lung cancer screening to develop a blood-based lung cancer detection test that when positive is followed by an LDCT. Changes in genome-wide cell-free DNA (cfDNA) fragmentation profiles (fragmentomes) in peripheral blood reflected genomic and chromatin characteristics of lung cancer. We applied machine learning to fragmentome features to identify individuals who were more or less likely to have lung cancer. We trained the classifier using 576 cases and controls from study samples, and then validated it in a held-out group of 382 cases and controls. The validation demonstrated high sensitivity for lung cancer, and consistency across demographic groups and comorbid conditions. Applying test performance to the screening eligible population in a five-year model with modest utilization assumptions suggested the potential to prevent thousands of lung cancer deaths.

Prognostic Implications of Small Cell Lung Cancer Transcriptional Subtyping for CNS Metastases.

PURPOSE: Small cell lung cancer (SCLC) often metastasizes to the brain and has poor prognosis. SCLC subtypes distinguished by expressing transcriptional factors ASCL1 or NEUROD1 have been identified. This study investigates the impact of transcription factor-defined SCLC subtype on incidence and outcomes of brain metastases (BMs). METHODS: Patients with SCLC with ASCL1 (A) and NEUROD1 (N) immunohistochemical expression status were identified and classified: (1) A+/N-, (2) A+/N+, (3) A-/N+, and (4) A-/N-. Cumulative incidence competing risk analyses were used to assess incidence of CNS progression. Cox proportional hazards models were used for multivariable analyses of overall survival (OS) and CNS progression-free survival (CNS-PFS). RESULTS: Of 164 patients, most were either A+/N- or A+/N+ (n = 62, n = 63, respectively). BMs were present at diagnosis in 24 patients (15%). Among them, the 12-month cumulative incidence of subsequent CNS progression was numerically highest for A+/N- (50% [95% CI, 10.5 to 74.7]; P = .47). Among those BM-free at diagnosis, the 12-month cumulative incidence of CNS progression was numerically the highest for A+/N- (16% [95% CI, 7.5 to 27.9]) and A-/N+ (9.1% [95% CI, 0.0 to 34.8]; P = .20). Both subtypes, A+/N- and A-/N+, had worse OS compared with A+/N+ (A+/N-: hazard ratio [HR], 1.62 [95% CI, 1.01 to 2.51]; P < .05; A-/N+: HR, 3.02 [95% CI, 1.35 to 6.76]; P = .007). Excellent response rates (28, 65% CR/PR) across subtypes were seen in patients who had CNS-directed radiotherapy versus systemic therapy alone (9, 36% CR/PR). CONCLUSION: To our knowledge, this report is the first to investigate CNS-specific outcomes based on transcription factor subtypes in patients with SCLC. BM-free patients at diagnosis with A+/N- or A-/N+ subtypes had worse outcomes compared with those with transcriptional factor coexpression. Further investigation into the mechanisms and implications of SCLC subtyping on CNS-specific outcomes is warranted to ultimately guide personalized care.

Real-World Use of Hypofractionated Radiotherapy for Primary CNS Tumors in the Elderly, and Implications on Medicare Spending.

BACKGROUND: For elderly patients with high-grade gliomas, 3-week hypofractionated radiotherapy (HFRT) is noninferior to standard long-course radiotherapy (LCRT). We analyzed real-world utilization of HFRT with and without systemic therapy in Medicare beneficiaries treated with RT for primary central nervous system (CNS) tumors using Centers for Medicare & Medicaid Services data. METHODS: Radiation modality, year, age (65-74, 75-84, or ≥85 years), and site of care (freestanding vs hospital-affiliated) were evaluated. Utilization of HFRT (11-20 fractions) versus LCRT (21-30 or 31-40 fractions) and systemic therapy was evaluated by multivariable logistic regression. Medicare spending over the 90-day episode after RT planning initiation was analyzed using multivariable linear regression. RESULTS: From 2015 to 2019, a total of 10,702 RT courses (ie, episodes) were included (28% HFRT; 65% of patients aged 65-74 years). A considerable minority died within 90 days of RT planning initiation (n=1,251; 12%), and 765 (61%) of those received HFRT. HFRT utilization increased (24% in 2015 to 31% in 2019; odds ratio [OR], 1.2 per year; 95% CI, 1.1-1.2) and was associated with older age (≥85 vs 65-74 years; OR, 6.8; 95% CI, 5.5-8.4), death within 90 days of RT planning initiation (OR, 5.0; 95% CI, 4.4-5.8), hospital-affiliated sites (OR, 1.4; 95% CI, 1.3-1.6), conventional external-beam RT (vs intensity-modulated RT; OR, 2.7; 95% CI, 2.3-3.1), and no systemic therapy (OR, 1.2; 95% CI, 1.1-1.3; P<.001 for all). Increasing use of HFRT was concentrated in hospital-affiliated sites (P=.002 for interaction). Most patients (69%) received systemic therapy with no differences by site of care (P=.12). Systemic therapy utilization increased (67% in 2015 to 71% in 2019; OR, 1.1 per year; 95% CI, 1.0-1.1) and was less likely for older patients, patients who died within 90 days of RT planning initiation, those who received conventional external-beam RT, and those who received HFRT. HFRT significantly reduced spending compared with LCRT (adjusted ß for LCRT = +$8,649; 95% CI, $8,544-$8,755), whereas spending modestly increased with systemic therapy (adjusted ß for systemic therapy = +$270; 95% CI, $176-$365). CONCLUSIONS: Although most Medicare beneficiaries received LCRT for primary brain tumors, HFRT utilization increased in hospital-affiliated centers. Despite high-level evidence for elderly patients, discrepancy in HFRT implementation by site of care persists. Further investigation is needed to understand why patients with short survival may still receive LCRT, because this has major quality-of-life and Medicare spending implications.

Artificial-intelligence-driven measurements of brain metastases' response to SRS compare favorably with current manual standards of assessment.

Background: Evaluation of treatment response for brain metastases (BMs) following stereotactic radiosurgery (SRS) becomes complex as the number of treated BMs increases. This study uses artificial intelligence (AI) to track BMs after SRS and validates its output compared with manual measurements. Methods: Patients with BMs who received at least one course of SRS and followed up with MRI scans were retrospectively identified. A tool for automated detection, segmentation, and tracking of intracranial metastases on longitudinal imaging, MEtastasis Tracking with Repeated Observations (METRO), was applied to the dataset. The longest three-dimensional (3D) diameter identified with METRO was compared with manual measurements of maximum axial BM diameter, and their correlation was analyzed. Change in size of the measured BM identified with METRO after SRS treatment was used to classify BMs as responding, or not responding, to treatment, and its accuracy was determined relative to manual measurements. Results: From 71 patients, 176 BMs were identified and measured with METRO and manual methods. Based on a one-to-one correlation analysis, the correlation coefficient was R2 = 0.76 (P = .0001). Using modified BM response classifications of BM change in size, the longest 3D diameter data identified with METRO had a sensitivity of 0.72 and a specificity of 0.95 in identifying lesions that responded to SRS, when using manual axial diameter measurements as the ground truth. Conclusions: Using AI to automatically measure and track BM volumes following SRS treatment, this study showed a strong correlation between AI-driven measurements and the current clinically used method: manual axial diameter measurements.

40 Gray in 5 Fractions for Salvage Reirradiation of Spine Lesions Previously Treated With Stereotactic Body Radiotherapy.

BACKGROUND AND PURPOSE: A retrospective single-center analysis of the safety and efficacy of reirradiation to 40 Gy in 5 fractions (reSBRT) in patients previously treated with stereotactic body radiotherapy to the spine was performed. METHODS: We identified 102 consecutive patients treated with reSBRT for 105 lesions between 3/2013 and 8/2021. Sixty-three patients (61.8%) were treated to the same vertebral level, and 39 (38.2%) to overlapping immediately adjacent levels. Local control was defined as the absence of progression within the treated target volume. The probability of local progression was estimated using a cumulative incidence curve. Death without local progression was considered a competing risk. RESULTS: Most patients had extensive metastatic disease (54.9%) and were treated to the thoracic spine (53.8%). The most common regimen in the first course of stereotactic body radiotherapy was 27 Gy in 3 fractions, and the median time to reSBRT was 16.4 months. At the time of simulation, 44% of lesions had advanced epidural disease. Accordingly, 80% had myelogram simulations. Both the vertebral body and posterior elements were treated in 86% of lesions. At a median follow-up time of 13.2 months, local failure occurred in 10 lesions (9.5%). The 6- and 12-month cumulative incidences of local failure were 4.8% and 6%, respectively. Seven patients developed radiation-related neuropathy, and 1 patient developed myelopathy. The vertebral compression fracture rate was 16.7%. CONCLUSION: In patients with extensive disease involvement, reSBRT of spine metastases with 40 Gy in 5 fractions seems to be safe and effective. Prospective trials are needed to determine the optimal dose and fractionation in this clinical scenario.

Intracranial Outcomes of De Novo Brain Metastases Treated With Osimertinib Alone in Patients With Newly Diagnosed EGFR-Mutant NSCLC.

Introduction: Patients with EGFR-mutant NSCLC have a high incidence of brain metastases. The EGFR-directed tyrosine kinase inhibitor osimertinib has intracranial activity, making the role of local central nervous system (CNS)-directed therapies, such as radiation and surgery, less clear. Methods: Patients with EGFR-mutant NSCLC and brain metastases who received osimertinib as initial therapy after brain metastasis diagnosis were included. Individual lesion responses were assessed using adapted RANO-BM criteria. CNS progression and local progression of brain metastasis from osimertinib start were analyzed using cumulative incidence treating death as a competing risk. Overall survival was estimated using Kaplan-Meier methodology. Results: There were 36 patients who had a median interval from brain metastasis diagnosis to first-line osimertinib initiation of 25 days. In total, 136 previously untreated brain metastases were tracked from baseline. Overall, 105 lesions (77.2%) had complete response and 31 had partial response reflecting best objective response of 100%. Best response occurred at a median of 96 days (range: 28-1113 d) from baseline magnetic resonance imaging. This reflects a best objective response rate of 100%. Two-year overall survival was 80%. CNS progression rates at 1-, 2-, and 3-years post-osimertinib were 21%, 32%, and 41%, respectively. Lesion-level local failure was estimated to be 0.7% and 4.7% at 1- and 2-years post-osimertinib, respectively. No clinicodemographic factors including brain metastasis number were associated with post-osimertinib progression. Conclusions: Intracranial response to osimertinib is excellent for patients with EGFR-mutant NSCLC with de novo, previously untreated brain metastases. Very low local failure rates support a strategy of upfront osimertinib alone in selected patients.

Outcomes Following Early Postoperative Adjuvant Radiosurgery for Brain Metastases.

Importance: Adjuvant stereotactic radiosurgery (SRS) enhances the local control of resected brain metastases (BrM). However, the risks of local failure (LF) and potential for posttreatment adverse radiation effects (PTRE) after early postoperative adjuvant SRS have not yet been established. Objective: To evaluate whether adjuvant SRS delivered within a median of 14 days after surgery is associated with improved LF without a concomitant increase in PTRE. Design, Setting, and Participants: This prospective cohort study examines a clinical workflow (RapidRT) that was implemented from 2019 to 2022 to deliver SRS to surgical patients within a median of 14 days, ensuring all patients were treated within 30 days postoperatively. This prospective cohort was compared with a historical cohort (StanRT) of patients with BrM resected between 2013 and 2019 to assess the association of the RapidRT workflow with LF and PTRE. The 2 cohorts were combined to identify optimal SRS timing, with a median follow-up of 3.3 years for survivors. Exposure: Timing of adjuvant SRS (14, 21, and 30 days postoperatively). Main Outcomes and Measures: LF and PTRE, according to modified Response Assessment in Neuro-Oncology Brain Metastases criteria. Results: There were 438 patients (265 [60.5%] female patients; 23 [5.3%] Asian, 27 [6.2%] Black, and 364 [83.1%] White patients) with a mean (SD) age of 62 (13) years; 377 were in the StanRT cohort and 61 in the RapidRT cohort. LF and PTRE rates at 1 year were not significantly different between RapidRT and StanRT cohorts. Timing of SRS was associated with radiographic PTRE. Patients receiving radiation within 14 days had the highest 1-year PTRE rate (18.08%; 95% CI, 8.31%-30.86%), and patients receiving radiation between 22 and 30 days had the lowest 1-year PTRE rate (4.10%; 95% CI, 1.52%-8.73%; P = .03). LF rates were highest for patients receiving radiation more than 30 days from surgery (10.65%; 95% CI, 6.90%-15.32%) but comparable for patients receiving radiation within 14 days, between 15 and 21 days, and between 22 and 30 days (≤14 days: 5.12%; 95% CI, 0.86%-15.60%; 15 to ≤21 days: 3.21%; 95% CI, 0.59%-9.99%; 22 to ≤30 days: 6.58%; 95% CI, 3.06%-11.94%; P = .20). Conclusions and Relevance: In this cohort study of adjuvant SRS timing following surgical resection of BrM, the optimal timing for adjuvant SRS appears to be within 22 to 30 days following surgery. The findings of this study suggest that this timing allows for a balanced approach that minimizes the risks associated with LF and PTRE.

Symptomatic Necrosis With Antibody-Drug Conjugates and Concurrent Stereotactic Radiotherapy for Brain Metastases.

This cohort study investigates whether brain metastases that manifest after stereotactic radiotherapy with concurrent antibody-drug conjugates are associated with an increased risk of symptomatic radiation necrosis.

Genomic analysis and clinical correlations of non-small cell lung cancer brain metastasis.

Up to 50% of patients with non-small cell lung cancer (NSCLC) develop brain metastasis (BM), yet the study of BM genomics has been limited by tissue access, incomplete clinical data, and a lack of comparison with paired extracranial specimens. Here we report a cohort of 233 patients with resected and sequenced (MSK-IMPACT) NSCLC BM and comprehensive clinical data. With matched samples (47 primary tumor, 42 extracranial metastatic), we show CDKN2A/B deletions and cell cycle pathway alterations to be enriched in the BM samples. Meaningful clinico-genomic correlations are noted, namely EGFR alterations in leptomeningeal disease (LMD) and MYC amplifications in multifocal regional brain progression. Patients who developed early LMD frequently have had uncommon, multiple, and persistently detectable EGFR driver mutations. The distinct mutational patterns identified in BM specimens compared to other tissue sites suggest specific biologic underpinnings of intracranial progression.

Characterization of Central Nervous System Clinico-Genomic Outcomes in ALK-Positive Non-Small Cell Lung Cancer Patients with Brain Metastases Treated with Alectinib.

INTRODUCTION: Highly effective brain-penetrant ALK-targeted tyrosine kinase inhibitors (TKIs) have been developed for the management of NSCLC patients with brain metastases (BM). Local therapy (LT) such as SRS or therapeutic craniotomy is increasingly being deferred for such patients. Herein we report detailed patient- and lesion-level intracranial outcomes and co-mutational genomic profiles from a cohort of NSCLC patients with BM treated with alectinib, with or without LT. METHODS: We retrospectively reviewed ALK fusion-positive NSCLC patients with BMs who received alectinib at the diagnosis of BM from 1/2012 and 5/2021. Outcome variables included intracranial progression-free survival (iPFS), overall survival (OS), duration of TKI therapy, and CNS response rates. Genomic characteristics from tumor specimens were assessed with MSK-IMPACT, a next-generation sequencing (NGS)-based genomic profiling assay. RESULTS: A total of 38 patients with 114 CNS lesions were included. Twelve of these patients also received contemporaneous LT (SRS, WBRT, or surgical resection). Maximal BM diameter in the TKI + LT group was greater (p < 0.003) but despite this difference, iPFS (TKI only, HR 1.21, 95 % CI 0.51-2.89; p = 0.66) and OS (TKI only, HR 5.99, 95 % CI 0.77-46.6; p = 0.052) were similar between groups and trended towards more favorable outcomes with the addition of LT. SMARCA4 co-alterations were associated with inferior OS (HR 8.76, 1.74-44.2; p = 0.009). CONCLUSIONS: Our study demonstrated that patients with ALK fusion-positive NSCLC treated with TKI + LT had larger BM and higher likelihood of pre-treatment neurologic symptoms. Despite these differences, iPFS was similar between groups. Results should be interpreted with caution as our study was limited by an underpowered sample size. SMARCA4 co-alterations were associated with inferior OS and these findings warrant further investigation.

Failure Patterns by PSMA PET for Recurrent Prostate Cancer after Prostatectomy and Salvage Radiation.

OBJECTIVE: To characterize patterns of failure using prostate-specific membrane antigen positron emission tomography (PSMA PET) after radical prostatectomy (RP) and salvage radiotherapy (SRT). METHODS: Patients with rising PSA post-RP+SRT underwent 68Ga-HBED-iPSMA PET/CT on a single-arm, prospective imaging trial (NCT03204123). Scans were centrally reviewed with pattern-of-failure analysis by involved site. Positive scans were classified using 3 failure categories: pelvic nodal, extra-pelvic nodal or distant non-nodal. Associations with failure categories were analyzed using cumulative incidence and generalized logits regression. RESULTS: We included 133 men who received SRT a median of 20 months post-RP; 56% received SRT to the prostatic fossa alone, while 44% received pelvic SRT. PSMA PET/CT was performed a median of 48 months post-SRT. Overall, 31% of PSMA PET/CT scans were negative, 2% equivocal and 67% had at least 1 positive site. Scan detection was significantly associated with PSA level prior to PSMA PET/CT. Analysis of 89 positive scans demonstrated pelvic nodal (53%) was the most common relapse and fossa relapse was low (9%). Overall, positive scans were pelvic (n = 35, 26%), extra-pelvic nodal (n = 26, 20%) or distant non-nodal failure (n = 28, 21%), and 70% of positive scans were oligorecurrent. We observed similar cumulative incidence for all failure categories and relatively few clinicodemographic associations. Men treated with pelvic SRT had reduced odds of pelvic failure versus exclusive fossa treatment. CONCLUSION: Pelvic, extra-pelvic nodal, and distant non-nodal failures occur with similar incidence post-SRT. Regional nodal relapse is relatively common, especially with fossa-only SRT. A high oligorecurrence rate suggests a potentially important role for PSMA-guided focal therapies.

Fractionated Proton Radiation Therapy and Hearing Preservation for Vestibular Schwannoma: Preliminary Analysis of a Prospective Phase 2 Clinical Trial.

BACKGROUND: Local management for vestibular schwannoma (VS) is associated with excellent local control with focus on preserving long-term serviceable hearing. Fractionated proton radiation therapy (FPRT) may be associated with greater hearing preservation because of unique dosimetric properties of proton radiotherapy. OBJECTIVE: To investigate hearing preservation rates of FPRT in adults with VS and secondarily assess local control and treatment-related toxicity. METHODS: A prospective, single-arm, phase 2 clinical trial was conducted of patients with VS from 2010 to 2019. All patients had serviceable hearing at baseline and received FPRT to a total dose of 50.4 to 54 Gy relative biological effectiveness (RBE) over 28 to 30 fractions. Serviceable hearing preservation was defined as a Gardner-Robertson score of 1 to 2, measured by a pure tone average (PTA) of ≤50 dB and a word recognition score (WRS) of ≥50%. RESULTS: Twenty patients had a median follow-up of 4.0 years (range 1.0-5.0 years). Local control at 4 years was 100%. Serviceable hearing preservation at 1 year was 53% (95% CI 29%-76%), and primary end point was not yet reached. Median PTA and median WRS both worsened 1 year after FPRT (P < .0001). WRS plateaued after 6 months, whereas PTA continued to worsen up to 1 year after FPRT. Median cochlea D90 was lower in patients with serviceable hearing at 1 year (40.6 Gy [RBE] vs 46.9 Gy [RBE]), trending toward Wilcoxon rank-sum test statistical significance (P = .0863). Treatment was well-tolerated, with one grade 1 cranial nerve V dysfunction and no grade 2+ cranial nerve dysfunction. CONCLUSION: FPRT for VS did not meet the goal of serviceable hearing preservation. Higher cochlea doses trended to worsening hearing preservation, suggesting that dose to cochlea correlates with hearing preservation independent of treatment modality.

Recent Advances and Applications of Radiation Therapy for Brain Metastases.

PURPOSE OF REVIEW: Radiation therapy (RT) is a mainstay of treatment for brain metastases from solid tumors. Treatment of these patients is complex and should focus on minimizing symptoms, preserving functional status, and prolonging survival. RECENT FINDINGS: Whole-brain radiotherapy (WBRT) can lead to toxicity, and while it does reduce recurrence in the CNS, this has not been shown to provide a survival benefit. Recent advances focus on reducing the toxicity of WBRT or using more targeted radiation therapy. New paradigms including the use of proton RT for leptomeningeal metastases (LM) and stereotactic radiosurgery (SRS) before craniotomy hold promise in improving treatment efficacy and reducing toxicity. Omission or replacement of WBRT is often safe and the use of SRS is expanding to include patients with more lesions and preoperative RT. Proton RT holds promise for LM. Progress is being made in improving patient-centered outcomes and reducing toxicity for patients with brain metastases.

Dosimetric Modeling of Lymphopenia in Patients With Metastatic Cancer Receiving Palliative Radiation and PD-1 Immune Checkpoint Inhibitors.

PURPOSE: Radiation therapy (RT)-associated lymphopenia may adversely affect treatment outcomes, particularly in the era of immunotherapy. We sought to determine dosimetric factors correlated with lymphopenia after palliative RT in a cohort of patients with advanced cancer treated with anti-PD-1 immune checkpoint inhibitors. METHODS AND MATERIALS: We included patients with metastatic lung cancer, melanoma, or renal cell carcinoma who were treated with either pembrolizumab or nivolumab and received palliative RT to an extracranial site. Baseline and nadir absolute lymphocyte counts (ALCs) within 6 weeks of RT were recorded. Dosimetric factors were extracted from the corresponding dose-volume histograms and also used to model the dose to circulating lymphocytes via a whole-body blood flow model that simulates the spatiotemporal distribution of blood particles in major organs during RT. RESULTS: We analyzed 55 patients who underwent 80 total courses of palliative RT; most (94%) were treated with 3-dimensional conformal RT. Doses to the whole body, bone, and large blood vessels (LBVs) were negatively correlated with the ALC nadir, with the strongest correlations seen at V15 (rs, -0.38, -0.43, and -0.37, and P = .0004, .0001, and .0008, respectively). Doses to other organs were not significantly correlated with the ALC nadir. The modeled dose to circulating lymphocytes was also negatively correlated with the ALC nadir and percent ALC change (for D2%, rs, -0.31 and -0.44, and P = .005 and .0001, respectively). Grade ≥3 lymphopenia was associated with LBV V15 (odds ratio [OR], 1.16; 95% CI, 1.07-1.26; P < .001), bone V15 (OR, 1.04; 95% CI, 1.01-1.08; P = .03), body V15 (OR, 1.003; 95% CI, 1.001-1.006; P = .008), and modeled lymphocyte dose (OR, 1.45; 95% CI, 1.16-1.82; P < .001). CONCLUSIONS: The RT dose to the whole body, bone, and LBVs and the modeled dose to circulating lymphocytes were correlated with lymphopenia in patients treated with palliative RT and anti-PD-1 immune checkpoint inhibitors. These findings may inform future radiation planning in this setting.