The Impact of Prophylactic Cranial Irradiation and Consolidative Thoracic Radiation Therapy for Extensive Stage Small-Cell Lung Cancer in the Transition to the Chemo-Immunotherapy Era: A Single Institution Series

INTRODUCTION

Extensive-stage small-cell lung cancer (ES-SCLC) continues to have poor survival due to its aggressive behavior, despite improvements with incorporation of immunotherapy with standard chemotherapy. Controversy exists regarding the role of consolidative thoracic radiation therapy (TRT) and prophylactic cranial irradiation (PCI) in ES-SCLC due to high recurrence rates. We report our institutional result of the benefit of PCI and TRT in ES-SCLC.

METHODS

Patients with ES-SCLC without intracranial metastasis at diagnosis (N = 163) were included. All patients completed systemic therapy with or without immunotherapy based on time of standard of care. Cohorts were divided by systemic therapy use and further subdivided by treatment with PCI and TRT. Overall survival (OS) and progression-free survival (PFS) were estimated by the Kaplan-Meier method with log-rank test for comparison. The effects of TRT and PCI were estimated by multivariable (MVA) Cox regression.

RESULTS

Seventy-four patients (45.4%) received TRT, and 33.1% (n = 54) received PCI. The median follow-up was 11 months (3-85 months). PCI improved median OS to 15 months from 10 months, P = .02) and median PFS to 8.5 months from 5 months (P = .02) which remained significant on MVA, P = .02 and P = .02, respectively. TRT improved OS on UVA (P = 0.002) but was not significant on MVA. TRT did not improve PFS.

CONCLUSION

This study including chemotherapy and chemo-immunotherapy suggests improved outcomes with addition of PCI in patients with ES-SCLC while TRT did not show benefit to either OS or PFS. A future trial is needed to evaluate the role of TRT and PCI in the era of chemo-immunotherapy.

Progression-Free Survival as a Surrogate Endpoint of Overall Survival in Patients with Locally Advanced Non-Small Cell Lung Cancer Treated with Chemoradiotherapy: Trial-Level Meta-Analysis and Individual-Level Analysis of NRG/RTOG 0617 and PROCLAIM

PURPOSE/OBJECTIVE(S)

Overall Survival (OS) is the gold standard endpoint in randomized clinical trials (RCTs) of Locally Advanced Non-Small Cell Lung Cancer (LA-NSCLC). Intermediate endpoints that can be observed at earlier time points and predict OS would improve trial efficiency and expedite the adoption of proven interventions.

MATERIALS/METHODS

Atrial-level meta-analysis was conducted using a weighted regression analysis to quantify the correlation between PFS and OS hazard ratios (HRs). Large (n≥ 100) contemporary RCTs in LA-NSCLC that used platinum-based chemoradiation were included. An individual-level surrogacy analysis based on Prentice criteria was performed to evaluate if PFS could reliably predict OS using NRG/RTOG 0617 (NCT00533949), a phase III RCT of dose escalated CRT. The individual-level correlation between PFS and OS was validated using PROCLAIM (NCT00686959) control arm.

RESULTS

Nineteen RCTs comprising a total of 5525 patients (pts) were included in the trial-level meta-analysis. A moderately high correlation was observed between PFS HR and OS HR (R2 = 0.68, 95% CI = 0.42-0.94). Individual-level analysis of NRG/RTOG 0617 showed that, as reported, RT dose was associated with OS (HR = 1.28, 95% CI = 1.04-1.58, p = 0.02) and PFS (HR = 1.21, 95% CI = 0.99-1.46, p = 0.06). Progressive disease (PD) was highly associated with OS, where pts having PD within 6mo or 12mo had a significantly higher mortality risk than those not having PD within 6mo or 12 mo, respectively, in landmark analysis (PD within 6mo: HR = 2.56, 95% CI = 1.82-3.59, p<0.0001; PD within 12mo: HR = 3.18, 95% CI = 2.45-4.12, p<0.0001). Accounting for PD moderately reduced RT dose effect on OS (HR = 1.21, 95% CI = 0.98-1.49), suggesting RT dose effect on OS may be mediated partially through PD. The association between OS and PD occurrence within 6mo or 12mo was similar in PROCLAIM control arm (PD within 6mo: HR = 2.06, 95% CI = 1.48-2.86, p<0.0001; PD within 12mo: HR = 2.02, 95% CI = 1.38-2.95, p<0.0001).

CONCLUSION

A moderately high trial-level surrogacy between PFS and OS was identified in trial-level meta-analysis. PD occurrence also reliably predicted OS at the individual patient level in both NRG/RTOG 0617 and PROCLAIM. These results support the use of PFS as a valid endpoint in clinical trials of LA-NSCLC.

Abstract 4936: Activity of carfilzomib in head and neck cancer cell lines in vitro

Background: Carfilzomib (CF) is a 2nd generation proteasome inhibitor with activity in hematologic cancer, but its study in solid tumors like squamous cell carcinoma of the head and neck (SCCHN) is limited. We investigated its antitumor activity in three SCCHN cell lines.

Methods: Cells: We studied two human tongue cell lines (CAL27; SCC-25) and one pharynx line (FaDu); all HPV-negative and p53-mutant. MTT assays: We utilized MTT assays to evaluate cytotoxicity of CF, cisplatin, and their combination. The IC50 of CF and Combination Index (CI) of varying concentrations of combined CF and cisplatin were calculated. Clonogenic assays: Cells were seeded at low density and after 24 hours, cells were treated with varying concentrations of CF. Plates were incubated for 10 days. The cells were fixed and stained with crystal violet dye and colonies counted. Wound Healing assays: After cells reached 100% confluence, a scratch was created using a 200 µL micropipette. Cells were treated with CF and images were acquired at 0, 24, 48, and 72 hours post-scratch.

Results: MTT assays: IC50 values as a function of exposure lengths are shown in Table 1. CAL27 was the most sensitive while SCC-25 was the most resistant. In all cell lines, the results of combined CF and cisplatin were complex: at lower doses there was evidence of antagonism, while at higher doses there was synergy. Clonogenic assays: CF significantly inhibited clonogenicity compared to DMSO control (P≤ 0.05). The surviving fraction for CF 2.5, 5, and 10 nM were 0.411. 0.151, 0.051, and 0.5, 0.339, 0.102 in CAL27 and SCC-25 cell lines, respectively. Wound Healing assays: Wound closure % after treatment with CF5 was significantly different from DMSO control (P≤0.05). Wound closure % for CF5 were 30.97, 56.75, and 28.03% compared to 94.65, 75.88, and 42.05% for control in CAL27, FaDu, and SCC-25 cell lines, respectively.

Conclusion: CF exhibits antitumor effects in SCCHN in vitro. Our findings support further investigation of CF in combination with conventional agents in vitro and in vivo.

IC50 values for carfilzomib in head and neck cancer cell lines Cell line 24 hours 48 hours 72 hours CAL27 18.02 (11.76- 28.22) 9.364 (7.189- 12.45) 6.401 (5.579- 7.373) FaDu 57.34 (41.98-84.90) 16.22 (13.438- 19.446) 8.237 (7.260- 9.365) SCC25 77.78 (67.18- 91.30) 12.87 (11.36- 14.64) 11.49 (10.51- 12.58)

Citation Format: Abdullah S. Eldaly, Douglas B. Stairs, Mitchell Machtay. Activity of carfilzomib in head and neck cancer cell lines in vitro. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4936.

Safety of Nivolumab Added to Chemoradiation Therapy Platforms for Intermediate and High-Risk Locoregionally Advanced Head and Neck Squamous Cell Carcinoma: RTOG Foundation 3504

PURPOSE

Programmed death-1 immune checkpoint blockade improves survival of patients with recurrent/metastatic head and neck squamous cell carcinoma (HNSCC), but the benefits of addition to (chemo)radiation for newly diagnosed patients with HNSCC remain unknown.

METHODS AND MATERIALS

We evaluated the safety of nivolumab concomitant with 70 Gy intensity modulated radiation therapy and weekly cisplatin (arm 1), every 3-week cisplatin (arm 2), cetuximab (arm 3), or alone for platinum-ineligible patients (arm 4) in newly diagnosed intermediate- or high-risk locoregionally advanced HNSCC. Patients received nivolumab from 2 weeks prior to radiation therapy until 3 months post-radiation therapy. The primary endpoint was dose-limiting toxicity (DLT). If ≤2 of the first 8 evaluable patients experienced a DLT, an arm was considered safe. Secondary endpoints included toxicity and feasibility of adjuvant nivolumab to 1 year, defined as all 7 additional doses received by ≥4 of the first 8 evaluable patients across arms.

RESULTS

Of 39 patients (10 in arms 1, 3, 4 and 9 in arm 2), 72% had T3-4 tumors, 85% had N2-3 nodal disease, and 67% had >10 pack-years of smoking. There were no DLTs in arms 1 and 2, 1 in arm 3 (mucositis), and 2 in arm 4 (lipase elevation and mucositis in 1 and fatigue in another). The most common grade ≥3 nivolumab-related adverse events were lipase increase, mucositis, diarrhea, lymphopenia, hyponatremia, leukopenia, fatigue, and serum amylase increase. Adjuvant nivolumab was feasible as defined in the protocol.

CONCLUSIONS

Concomitant nivolumab with the 4 tested regimens was safe for patients with intermediate- and high-risk HNSCC, and subsequent adjuvant nivolumab was feasible as defined (NCT02764593).

Low-risk meningioma: Initial outcomes from NRG Oncology/RTOG 0539

BACKGROUND

Three- and five-year progression-free survival (PFS) for low-risk meningioma managed with surgery and observation reportedly exceeds 90%. Herewith we summarize outcomes for low-risk meningioma patients enrolled on NRG/RTOG 0539.

METHODS

This phase II trial allocated patients to one of three groups per World Health Organization grade, recurrence status, and resection extent. Low-risk patients had either gross total (GTR) or subtotal resection (STR) for a newly diagnosed grade 1 meningioma and were observed after surgery. The primary endpoint was 3-year PFS. Adverse events (AEs) were scored using Common Terminology Criteria for Adverse Events (CTCAE) version 3.

RESULTS

Among 60 evaluable patients, the median follow-up was 9.1 years. The 3-, 5-, and 10-year rates were 91.4% (95% CI, 84.2 to 98.6), 89.4% (95% CI, 81.3 to 97.5), 85.0% (95% CI, 75.3 to 94.7) for PFS and 98.3% (95% CI, 94.9 to 100), 98.3%, (95% CI, 94.9 to 100), 93.8% (95% CI, 87.0 to 100) for overall survival (OS), respectively. With centrally confirmed GTR, 3/5/10y PFS and OS rates were 94.3/94.3/87.6% and 97.1/97.1/90.4%. With STR, 3/5/10y PFS rates were 83.1/72.7/72.7% and 10y OS 100%. Five patients reported one grade 3, four grade 2, and five grade 1 AEs. There were no grade 4 or 5 AEs.

CONCLUSIONS

These results prospectively validate high PFS and OS for low-risk meningioma managed surgically but raise questions regarding optimal management following STR, a subcohort that could potentially benefit from adjuvant therapy.

A Volume-Independent Conformity Index for Stereotactic Radiosurgery

PURPOSE

To develop a volume-independent conformity metric called the Gaussian Weighted Conformity Index (GWCI) to evaluate stereotactic radiosurgery/radiotherapy (SRS/SRT) plans for small brain tumors.

METHODS

A signed bi-directional local distance (BLD) between the prescription isodose line and the target contour is determined for each point along the tumor contour (positive distance represents under-coverage). A similarity score function is derived from Gaussian function, penalizing under- and over-coverage at each point by assigning standard deviations of the Gaussian function. Each point along the dose line contour is scored with this score function. The average of the similarity scores determines the GWCI. A total of 40 targets from 18 patients who received Gamma-Knife SRS/SRT treatments were analyzed to determine appropriate penalty criteria. The resulting GWCIs for test cases already deemed clinically acceptable are presented and compared to the same cases scored with the New Conformity Index to determine the influence of tumor volumes on the two conformity indices.

RESULTS

A total of four penalty combinations were tested based on the signed BLDs from the 40 targets. A GWCI of 0.9 is proposed as a cutoff for plan acceptability. The GWCI exhibits no target volume dependency as designed.

CONCLUSION

A limitation of current conformity indices, volume dependency, becomes apparent when applied to SRS/SRT plans. The GWCI appears to be a more robust index which penalizes over- and under-coverage of tumors and is not skewed by the tumor volume. This article is protected by copyright. All rights reserved.

Adding Base-Excision Repair Inhibitor TRC102 to Standard Pemetrexed-Platinum-Radiation in Patients with Advanced Nonsquamous Non-Small Cell Lung Cancer: Results of a Phase I Trial

PURPOSE

TRC102, a small-molecule base-excision repair inhibitor, potentiates the cytotoxicity of pemetrexed and reverses resistance by binding to chemotherapy-induced abasic sites in DNA. We conducted a phase I clinical trial combining pemetrexed and TRC102 with cisplatin-radiation in stage III nonsquamous non-small cell lung cancer (NS-NSCLC).

PATIENTS AND METHODS

Fifteen patients were enrolled from 2015 to 2019. The primary objective was to determine the dose-limiting toxicity and maximum tolerated dose of TRC102 in combination with pemetrexed, cisplatin, and radiotherapy. Secondary objectives were to assess toxicity, tumor response, and progression-free survival at 6 months. Based on our preclinical experiments, pemetrexed-TRC102 was given on day 1, and cisplatin/radiotherapy was initiated on day 3. This schedule was duplicated in the second cycle. After completion, two additional cycles of pemetrexed-cisplatin were given. Toxicities were assessed using NCI CTACAE versions 4/5.

RESULTS

The median age was 69 years (45-79) with the median follow-up of 25.7 months (range, 7.9-47.4). No dose-limiting toxicities and no grade 5 toxicity were seen. Hematologic and gastrointestinal toxicities were the most common side effects. No clinical radiation pneumonitis was seen. Of 15 evaluable patients, three had complete response (20%), and 12 had partial response (80%). The 6-month progression-free survival was 80%, and the 2-year overall survival was 83%.

CONCLUSIONS

Pemetrexed-TRC102 combined with cisplatin/radiotherapy in NS-NSCLC is safe and well tolerated. The recommended phase II dose is 200 mg TRC102 along with cisplatin-pemetrexed. No additional safety signal was seen beyond the expected CRT risks. A phase II trial, integrating post-CRT immunotherapy with this aggressive DNA-damaging regimen, is warranted.

A Comparative Study of Patients With Early-Stage Non-Small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy Using CyberKnife and Linear Accelerator-Based Volumetric Modulated Arc Therapy

PURPOSE

Stereotactic body radiation therapy (SBRT) has become the standard of care for medically inoperable early-stage non-small cell lung cancer. We investigated 2 modalities of lung SBRT, CyberKnife (CK) and volumetric modulated arc therapy (VMAT), for differences in dosimetric parameters, tumor control, and clinical outcomes.

METHODS AND MATERIALS

Patients who underwent SBRT for T1-2N0M0 non-small cell lung cancer from 2012 to 2018 were included. Dosimetric parameters for target volume coverage and organ-at-risk dose distribution were collected. Survival outcomes were evaluated using the Kaplan-Meier method with log-rank test. A multivariate Cox proportional hazards model was analyzed for local, regional, and distant tumor control; overall survival (OS) and progression-free survival; and radiation pneumonitis.

RESULTS

Two hundred twenty-seven patients (142 CK, 85 VMAT SBRT) met inclusion criteria. Overall, the local, regional, and distant control rates were 89.3%, 86.3%, and 87.4% at 2 years, and the OS was 67.5% and 32.8% at 2 and 5 years, respectively. VMAT delivered higher maximum doses to the gross tumor volume and planning target volume and had a lower lung and heart V₅. Although there was no difference in local or distant failure, progression-free survival, or OS, VMAT was associated with superior freedom from regional failure (adjusted hazard ratio, 0.26; P = .045). With no difference between treatment modalities, 11.9% of patients developed grade 1 to 2 radiation pneumonitis. There were no grade 3+ events of radiation pneumonitis.

CONCLUSIONS

This study revealed that VMAT and CK provided comparable local and distant control and survival outcomes; however, VMAT exhibited better regional control. Further study in this regard is imperative.

Pretreatment neutrophil-to-lymphocyte ratio as an important prognostic marker in stage III locally advanced non-small cell lung cancer: confirmatory results from the PROCLAIM phase III clinical trial

Background

Neutrophil-to-lymphocyte ratio (NLR) is an important pretreatment marker of systemic inflammation and tumor aggressiveness. Increased levels of this ratio have been associated with reduced survival in several observational studies of lung cancer. However, supporting analyses from large clinical trial data are lacking.

Methods

To validate the prognostic role of NLR, the current study evaluated data from a randomized phase III study (PROCLAIM; clinicaltrial.gov ID: NCT00686959) of patients with stage IIIA/B, unresectable, non-squamous, non-small cell lung cancer (NSCLC), originally comparing combination pemetrexed-cisplatin chemoradiotherapy with etoposide-cisplatin chemoradiotherapy. Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for survival were estimated using a Cox proportional hazards model. Models were adjusted for age, race, sex, stage, treatment, and body mass index (BMI). Patients were followed for a median of 24 months.

Results

Increased NLR levels at baseline were associated with reduced overall (P_Trend <0.0001) and progression-free survival (P_Trend <0.005). A similar but decreasing linear trend was not observed for lymphocytes count alone.

Conclusions

These findings provide substantiating evidence that NLR, which is routinely available from standard blood testing of patients diagnosed with NSCLC, is an important inflammation-based prognostic marker for survival among patients with locally advanced disease undergoing chemoradiation. Future research will benefit by assessing the prognostic potential of NLR in the context of genetic mutations and molecular markers.

Focal Prostate Stereotactic Body Radiation Therapy With Correlative Pathological and Radiographic-Based Treatment Planning

Introduction

Advances in multiparametric MRI (mpMRI) combining anatomic and functional imaging can accurately identify foci of adenocarcinoma within the prostate, offering the possibility of partial gland therapy. We performed tandem prospective pilot trials to investigate the feasibility of focal prostate SBRT (f-SBRT) based on correlating diagnostic mpMRI and biopsies with confirmatory pathology in treatment planning.

Materials and Methods

Patients with pathologic focal Gleason 6–7 disease and a corresponding PIRADS 4–5 lesion on mpMRI underwent targeted and comprehensive biopsies using MRI/ultrasound fusion under electromagnetic sensor navigation. After rigorous analysis for imaging biopsy concordance, five of 18 patients were eligible to proceed to f-SBRT. Chi-squared test was used for differences from expected outcomes, and concordance was estimated with binomial distribution theory and Wilson’s method.

Results

Six patients had Gleason 6 and 12 had Gleason 3 + 4 disease (mean PSA: 5.8 ng/ml, range: 2.2–8.4). Absolute concordance was 43.8% (95% CI: 0.20, 0.64). Patterns of discordance included additional sites of ipsilateral disease, bilateral disease, and negative target. Five were upstaged to a new NCCN risk category necessitating treatment escalation. The five patients with concordant pathology completed three-fraction f-SBRT with sparing of the surrounding normal structures (including contralateral neurovascular bundle), with no reported grade 2+ toxicities and favorable PSA responses (mean: 41% decrease).

Conclusions

On our pilot trials of f-SBRT planning using rigorous imaging and pathology concordance, image-guided confirmatory biopsies frequently revealed additional disease, suggesting the need for caution in partial-gland therapy. For truly focal disease, f-SBRT provided excellent dosimetry, minimal toxicity, and encouraging biochemical response. Clinical Trial Registration: www.clinicaltrials.gov, NCT02681614; NCT02163317.

Impact of effective dose to immune cells (EDIC) on lymphocyte nadir and survival in limited-stage SCLC

BACKGROUND

Effective dose to immune cell (EDIC), an estimated radiation dose to the circulating lymphocytes, is of significance for overall survival (OS) in non-small cell lung cancer. This study aimed to validate the EDIC's OS effect on limited-stage small cell lung cancer (LS-SCLC).

METHOD AND MATERIALS

This study included LS-SCLC patients received definitive chemo-radiation in one single center from 2012 to 2017. All patients had multiple complete-blood-count tests including lymphocyte count at pre-, during- and end- radiotherapy. EDIC, computed according to doses of the lung, heart, and the total body, was assessed for its correlation with lymphocyte nadir, OS and progression free survival (PFS).

RESULTS

Of 503 eligible patients, the mean EDIC was 7.34 Gy. The mean lymphocyte nadir was 0.48 × 10⁹ cells/L, significantly lower than 1.65 × 10⁹ cells/L at pre-radiotherapy (p < 0.001). EDIC was significantly correlated with lymphocyte nadir under both univariate (p < 0.001) and multivariable linear regression (p < 0.001). Multivariable analysis showed EDIC (HR = 0.1072, p = 0.005) and lymphocyte nadir (HR = 0.345, p = 0.003) were both significant for OS. EDIC was also significant for PFS (HR = 1.046, p = 0.026). The C-indexes of OS prediction were 0.593, 0.617, 0.676, and 0.684, for lymphocyte nadir alone, EDIC alone, combined lymphocyte nadir model, and combined EDIC model, respectively.

CONCLUSIONS

This study demonstrated that EDIC is an independent predictor for lymphocyte nadir, PFS and OS. EDIC may serve as a predictor for lymphocyte nadir and a surrogate marker for OS in LS-SCLC. More attention should be paid to EDIC to decease the lymphocyte toxicity and improve survival.

Telemedicine use and satisfaction amongst radiation oncologists during the COVID-19 pandemic: Evaluation of current trends and future opportunities

e13503

Background: During the COVID-19 pandemic telemedicine became an attractive alternative to in person appointments. The role of telemedicine in patients who undergo frequent on site treatment, such as radiation therapy, is unclear. The purpose of this study was to examine telemedicine use, physician satisfaction and barriers to continued use in radiation oncology. Methods: An anonymous, electronic survey was distributed to radiation oncologists internationally. Participants described demographic and practice characteristics and a 5 point Likert scale assessed provider satisfaction, ease of use and overall utility of telemedicine. Analyses include descriptive statistics and subgroup comparisons using Chi-square and Fisher’s exact test. Results: 232/5343 (4.3%) completed the survey, 63.8% of whom were male, 52.6% age 50 or younger and 78.0% from the United States (U.S.). Only 14.2% used Telemedicine previously, which increased to 93.1% during COVID-19. Amongst all telemedicine users, usage rates were 77.9% for initial consultations, 97.2% for follow-up visits, and 35.9% for on-treatment visits. 69.8% report that <25% of patients requiring treatment experienced delays due to COVID-19. Most conducted appointments from the workplace, with 40.1% also doing so from home. Satisfaction was high at 73.8%, perceived usefulness was 76.9% and 81.5% hope to continue using telemedicine after the pandemic. However, 82.4% had concerns with the inability to examine patients. Although 82.1 % believed that telemedicine would improve patient access to health care services overall, 63.0% were concerned with patient ability to access required technology. 49.5% had concerns regarding continued billing/reimbursement; less commonly at government centers (18.8%) compared to academic/satellite facilities (52.7%) and free-standing centers/community hospitals (50.7%), p=0.039 for both comparisons. These concerns were also significantly higher amongst US physicians (53.2% vs 34.9%, p=0.048). Conclusions: Widespread adoption of telemedicine by radiation oncologists occurred during COVID-19 with high rates of satisfaction and interest in continued use. Sustained reimbursement for telemedicine services is a significant concern, particularly in the US and outside of government facilities. [Table: see text]

NRG-RTOG 1106/ACRIN 6697: A phase IIR trial of standard versus adaptive (mid-treatment PET-based) chemoradiotherapy for stage III NSCLC—Results and comparison to NRG-RTOG 0617 (non-personalized RT dose escalation)

8548

Background: NRG-RTOG 0617 (R0617) found that non-personalized dose escalation of radiotherapy (RT) with concurrent chemotherapy was deleterious. NRG-RTOG 1106/ACRIN 6697 (R1106) studied adaptive chemoradiotherapy, using tumor and patient individualized RT dose intensification simultaneously with field reduction, based upon mid-treatment FDG-PET. Methods: The control arms of both studies used 60 Gy (+ weekly carboplatin/paclitaxel). The investigational arm of R0617 used 74 Gy in 37 fractions, with no field/dose adaptation, while R1106 used mid-treatment FDG-PET (after ̃40 Gy) to design an individualized dose adaptive RT plan with daily-fraction size 2.2 to 3.8 Gy (up to 80.4 Gy/30 fractions), based upon a model of isotoxic lung risk. Nearly all (93%) patients had IMRT. No patients had consolidation immunotherapy. The primary endpoint for R1106 was local-regional-progression freedom (LRPF) assessed by central review. Other endpoints reported here were survival, toxicity, and institution-defined local/regional control. Results: From 2012-2017, 127 patients were enrolled to R1106 (43 in the standard and 84 in the adaptive arms), with a median follow-up of 3.6 years. The median actual RT dose in the adaptive arm was 71 Gy (Q1-Q3 68-76 Gy). The 2-year LRPF was 59.5% versus 54.6% (p=0.66) for standard versus adaptive RT; the 3-year survival rates were 49.1% versus 47.5% (p=0.80). An exploratory analysis of 2-year in-field local primary tumor control and local-regional tumor control (institution-assessed) were 58.5% and 55.6% for standard RT, and 75.6% and 66.3% for adaptive RT, respectively. As shown in the table, there were no significant differences in cardiac or esophageal adverse events between the two arms; the adaptive RT arm had more Grade 3+ respiratory events (23.8% versus 14.3%). Conclusions: NRG-RTOG1106 did not meet its primary endpoint of demonstrating improved LRPF. Unlike R0617, there was no suggestion of a detrimental effect of adaptive dose-intensified RT on survival and cardiac events. Studies to refine personalized RT, especially in the immunotherapy era, should be considered. Outcome comparison between R0617 and R1106. Clinical trial information: NCT01507428. [Table: see text]

Radiotherapy and Receptor Tyrosine Kinase Inhibition for Solid Cancers (ROCKIT): A Meta-Analysis of 13 Studies

Background

We hypothesized that the addition of receptor tyrosine kinase inhibitors (RTKis, e.g., lapatinib, erlotinib, cetuximab, bevacizumab, panitumumab) to radiotherapy-based treatment for solid tumors does not increase overall survival but may increase toxicity.

Methods

Population, Intervention, Control, Outcome, Study Design; Preferred Reporting Items for Systematic Reviews and Meta-Analyses; and Meta-analysis of Observational Studies in Epidemiology methods were used to identify prospective randomized studies including patients with solid tumor cancers treated with radiotherapy with or without RTKis. Extracted variables included use of radiotherapy vs chemoradiotherapy, RTKi type (antibody vs small molecule), outcomes, and toxicities. The primary endpoint was overall survival; the secondary endpoint was grade 3+ toxicity. Random-effects meta-analyses were performed for each outcome measure. All statistical tests were 2-sided.

Results

A total of 405 studies met the initial search criteria, of which 13 prospective randomized trials of radiotherapy with or without RTKi met the inclusion criteria, encompassing 5678 patients. The trials included cancers of the head and neck (6 trials, 3295 patients), esophagus (3 trials, 762 patients), lung (2 trials, 550 patients), and brain (2 trials, 1542 patients). Three studies evaluated a small molecule and radiotherapy in 949 patients, and 10 studies evaluated antibodies and radiotherapy in 4729 patients. The addition of RTKis to radiotherapy-based treatment did not improve overall survival (hazard ratio = 1.02, 95% confidence interval = 0.90 to 1.15, P = .76) but increased grade 3+ toxicity (relative risk = 1.18, 95% confidence interval = 1.06 to 1.33, P = .009).

Conclusions

The addition of RTKis to radiotherapy does not improve survival and worsens toxicity.

Role of radiation in extensive stage small cell lung cancer: a National Cancer Database registry analysis

The role of prophylactic cranial irradiation (PCI) and thoracic radiation therapy (TRT) in extensive-stage small cell lung cancer remains controversial. The authors examined the National Cancer Database and identified patients with extensive-stage small cell lung cancer with no brain metastasis. Patients were excluded if they died 30 days from diagnosis, did not receive polychemotherapy, had other palliative radiation or had missing information. A propensity score-matched analysis was also performed. A total of 21,019 patients were identified. The majority of patients did not receive radiation (69%), whereas 10% received PCI and 21% received TRT. The addition of PCI and TRT improved median survival and survival at 1 and 2 years (p ≤ 0.05). The propensity score-matched analysis confirmed the same overall survival benefit with both PCI and TRT. This registry-based analysis of >1500 accredited cancer programs shows that PCI and TRT are not commonly utilized for extensive-stage small cell lung cancer patients who are treated with multiagent chemotherapy. The addition of PCI and TRT significantly improves overall survival in this otherwise poor prognostic group. Further research is needed to confirm the role of PCI and TRT, especially in the era of improved systemic therapy.

Risk groups of laryngeal cancer treated with chemoradiation according to nomogram scores - A pooled analysis of RTOG 0129 and 0522

OBJECTIVES

To develop nomograms predicting overall survival (OS), freedom from locoregional recurrence (FFLR), and freedom from distant metastasis (FFDM) for patients receiving chemoradiation for laryngeal squamous cell carcinoma (LSCC).

MATERIAL AND METHODS

Clinical and treatment data for patients with LSCC enrolled on NRG Oncology/RTOG 0129 and 0522 were extracted from the RTOG database. The dataset was partitioned into 70% training and 30% independent validation datasets. Significant predictors of OS, FFLR, and FFDM were obtained using univariate analysis on the training dataset. Nomograms were built using multivariate analysis with four a priori variables (age, gender, T-stage, and N-stage) and significant predictors from the univariate analyses. These nomograms were internally and externally validated using c-statistics (c) on the training and validation datasets, respectively.

RESULTS

The OS nomogram included age, gender, T stage, N stage, and number of cisplatin cycles. The FFLR nomogram included age, gender, T-stage, N-stage, and time-equivalent biologically effective dose. The FFDM nomogram included age, gender, N-stage, and number of cisplatin cycles. Internal validation of the OS nomogram, FFLR nomogram, and FFDM nomogram yielded c = 0.66, c = 0.66 and c = 0.73, respectively. External validation of these nomograms yielded c = 0.59, c = 0.70, and c = 0.73, respectively. Using nomogram score cutoffs, three risk groups were separated for each outcome.

CONCLUSIONS

We have developed and validated easy-to-use nomograms for LSCC outcomes using prospective cooperative group trial data.

Monte Carlo Dose Calculation Using MRI Based Synthetic CT Generated by Fully Convolutional Neural Network for Gamma Knife Radiosurgery

The aim of this work is to study the dosimetric effect from generated synthetic computed tomography (sCT) from magnetic resonance (MR) images using a deep learning algorithm for Gamma Knife (GK) stereotactic radiosurgery (SRS). The Monte Carlo (MC) method is used for dose calculations. Thirty patients were retrospectively selected with our institution IRB's approval. All patients were treated with GK SRS based on T1-weighted MR images and also underwent conventional external beam treatment with a CT scan. Image datasets were preprocessed with registration and were normalized to obtain similar intensity for the pairs of MR and CT images. A deep convolutional neural network arranged in an encoder-decoder fashion was used to learn the direct mapping from MR to the corresponding CT. A number of metrics including the voxel-wise mean error (ME) and mean absolute error (MAE) were used for evaluating the difference between generated sCT and the true CT. To study the dosimetric accuracy, MC simulations were performed based on the true CT and sCT using the same treatment parameters. The method produced an MAE of 86.6 ± 34.1 Hundsfield units (HU) and a mean squared error (MSE) of 160.9 ± 32.8. The mean Dice similarity coefficient was 0.82 ± 0.05 for HU > 200. The difference for dose-volume parameter D95 between the ground true dose and the dose calculated with sCT was 1.1% if a synthetic CT-to-density table was used, and 4.9% compared with the calculations based on the water-brain phantom.

Stereotactic body radiotherapy (SBRT) for T2N0 (>3 cm) non-small cell lung cancer: Outcomes and failure patterns

PURPOSE/OBJECTIVES

Outcomes of T2N0 lung cancer patients treated with stereotactic radiotherapy are not well known.

METHODS AND MATERIALS

We conducted a single institution retrospective review of patients with T2N0 NSCLC who were treated with SBRT. The local, regional, distant control rates were calculated from available clinical data. Survival outcomes were determined using the Kaplan Meier method.

RESULTS

Fifty-six patients met our selection criteria. The two-year local control rate was 84.2%. The two and 5-year disease-free survival (DFS) and OS were 31.9% and 15.3% and 39.9% and 12.1%, respectively. Centroid BED₁₀ > 150Gy was associated with improved DFS, (p = 0.014), and OS on univariable analysis (p=0.0132).

CONCLUSIONS

SBRT provides good local control for T2N0 NSCLC, but systemic failure remains problematic.

Multi-institutional Analysis of Prognostic Factors and Outcomes After Hypofractionated Stereotactic Radiotherapy to the Resection Cavity in Patients With Brain Metastases

IMPORTANCE

For brain metastases, the combination of neurosurgical resection and postoperative hypofractionated stereotactic radiotherapy (HSRT) is an emerging therapeutic approach preferred to the prior practice of postoperative whole-brain radiotherapy. However, mature large-scale outcome data are lacking.

OBJECTIVE

To evaluate outcomes and prognostic factors after HSRT to the resection cavity in patients with brain metastases.

DESIGN, SETTING, AND PARTICIPANTS

An international, multi-institutional cohort study was performed in 558 patients with resected brain metastases and postoperative HSRT treated between December 1, 2003, and October 31, 2019, in 1 of 6 participating centers. Exclusion criteria were prior cranial radiotherapy (including whole-brain radiotherapy) and early termination of treatment.

EXPOSURES

A median total dose of 30 Gy (range, 18-35 Gy) and a dose per fraction of 6 Gy (range, 5-10.7 Gy) were applied.

MAIN OUTCOMES AND MEASURES

The primary end points were overall survival, local control (LC), and the analysis of prognostic factors associated with overall survival and LC. Secondary end points included distant intracranial failure, distant progression, and the incidence of neurologic toxicity.

RESULTS

A total of 558 patients (mean [SD] age, 61 [0.50] years; 301 [53.9%] female) with 581 resected cavities were analyzed. The median follow-up was 12.3 months (interquartile range, 5.0-25.3 months). Overall survival was 65% at 1 year, 46% at 2 years, and 33% at 3 years, whereas LC was 84% at 1 year, 75% at 2 years, and 71% at 3 years. Radiation necrosis was present in 48 patients (8.6%) and leptomeningeal disease in 73 patients (13.1%). Neurologic toxic events according to the Common Terminology Criteria for Adverse Events grade 3 or higher occurred in 16 patients (2.8%) less than 6 months and 24 patients (4.1%) greater than 6 months after treatment. Multivariate analysis identified a Karnofsky Performance Status score of 80% or greater (hazard ratio [HR], 0.61; 95% CI, 0.46-0.82; P < .001), 22 to 33 days between resection and radiotherapy (HR, 1.50; 95% CI, 1.07-2.10; P = .02), and a controlled primary tumor (HR, 0.69; 95% CI, 0.52-0.90; P = .007) as prognostic factors associated with overall survival. For LC, a single brain metastasis (HR, 0.57; 95% CI, 0.35-0.93; P = .03) and a controlled primary tumor (HR, 0.59; 95% CI, 0.39-0.92; P = .02) were significant in the multivariate analysis.

CONCLUSIONS AND RELEVANCE

To date, this cohort study includes one of the largest series of patients with brain metastases and postoperative HSRT and appears to confirm an excellent risk-benefit profile of local HSRT to the resection cavity. Additional studies will help determine radiation dose-volume parameters and provide a better understanding of synergistic effects with systemic and immunotherapies.

Pre-radiotherapy lymphocyte count and platelet-to-lymphocyte ratio may improve survival prediction beyond clinical factors in limited stage small cell lung cancer: model development and validation

Background

Few small sample size studies have reported lymphocyte count was prognostic for survival in small-cell lung cancer (SCLC). This study aimed to validate this finding, to build prediction model for overall survival (OS) and to study whether novel models that combine lymphocyte-related variables can predict OS more accurately than a conventional model using clinical factors alone in a large cohort of limited-stage SCLC patients.

Methods

This study enrolled 544 limited-stage SCLC patients receiving definitive chemo-radiation with pre-radiotherapy lymphocyte-related variables including absolute lymphocyte count (ALC), platelet-to-lymphocyte ratio (P/L ratio), neutrophil-to-lymphocyte ratio (N/L ratio), and lymphocyte-to-monocyte ratio (L/M ratio). The primary endpoint was OS. These patients were randomly divided into a training dataset (n=274) and a validation dataset (n=270). Multivariate survival models were built in the training dataset, and the performance of these models were further tested in the validation dataset using the concordance index (C-index).

Results

The median follow-up time was 36 months for all patients. In the training dataset, univariate analysis showed that ALC (P=0.020) and P/L ratio (P=0.023) were significantly correlated with OS, while L/M ratio (P=0.091) and N/L ratio (P=0.436) were not. Multivariate modeling demonstrated the significance of ALC (P=0.063) and P/L ratio (P=0.003), and the improvement for OS prediction in combined models with the addition of ALC (C-index =0.693) or P/L ratio (C-index =0.688) over the conventional model (C-index =0.679). The validation dataset analysis confirmed a modest improvement of C-index with the addition of ALC or P/L ratio. All these models showed reasonable discriminations and calibrations.

Conclusions

This study validated the significant value of pre-radiotherapy ALC and P/L ratio on OS in limited-stage SCLC. The combined model with ALC or P/L ratio showed additional OS prediction values than the conventional model with clinical factors alone.

Clinical Study of Using Biometrics to Identify Patient and Procedure

PURPOSE

To reduce patient and procedure identification errors by human interactions in radiotherapy delivery and surgery, a Biometric Automated Patient and Procedure Identification System (BAPPIS) was developed. BAPPIS is a patient identification and treatment procedure verification system using fingerprints.

METHODS

The system was developed using C++, the Microsoft Foundation Class Library, the Oracle database system, and a fingerprint scanner. To register a patient, the BAPPIS system requires three steps: capturing a photograph using a web camera for photo identification, taking at least two fingerprints, and recording other specific patient information including name, date of birth, allergies, etc. To identify a patient, the BAPPIS reads a fingerprint, identifies the patient, verifies with a second fingerprint to confirm when multiple patients have same fingerprint features, and connects to the patient's record in electronic medical record (EMR) systems. To validate the system, 143 and 21 patients ranging from 36 to 98 years of ages were recruited from radiotherapy and breast surgery, respectively. The registration process for surgery patients includes an additional module, which has a 3D patient model. A surgeon could mark 'O' on the model and save a snap shot of patient in the preparation room. In the surgery room, a webcam displayed the patient's real-time image next to the 3D model. This may prevent a possible surgical mistake.

RESULTS

1,271 (96.9%) of 1,311 fingerprints were verified by BAPPIS using patients' 2nd fingerprints from 143 patients as the system designed. A false positive recognition was not reported. The 96.9% completion ratio is because the operator did not verify with another fingerprint after identifying the first fingerprint. The reason may be due to lack of training at the beginning of the study.

CONCLUSION

We successfully demonstrated the use of BAPPIS to correctly identify and recall patient's record in EMR. BAPPIS may significantly reduce errors by limiting the number of non-automated steps.

NCOG-33. HEMATOLOGIC PREDICTORS OF OUTCOMES IN GLIOBLASTOMA TREATED WITH SURGERY AND CHEMORADIATION

BACKGROUND

There are conflicting reports regarding the prognostic value of platelet and other blood counts in glioblastoma. However, few series have looked at all hematologic parameters simultaneously.

METHODS

We performed a retrospective chart review of patients diagnosed with supratentorial glioblastoma from 2014-2019 who started conventional chemoradiation following initial surgical biopsy and/or resection. Hematologic parameters were collected at baseline, in the preoperative and postoperative periods and at the initiation and completion of chemoradiation. This included platelet counts, hemoglobin levels, white blood cell counts (WBC), neutrophil and lymphocyte counts with neutrophil:lymphocyte (NLR) and platelet:lymphocyte ratios (PLR) calculated at each time point. Cox regression was performed to assess the association between each hematologic parameter and both overall survival (OS) and progression free survival (PFS). A multivariate Cox proportional hazards model adjusted for all hematologic parameters, age, sex, race and KPS was generated for each time point. All hematologic parameters were modeled as continuous variables.

RESULTS

A total of 58 patients met inclusion criteria. 18 were female and 40 male. The median age was 59.5 (range 43-82). Median follow up for all patients was 15.3 months. A total of 52 patients completed radiation therapy and 18 completed 6 cycles of adjuvant chemotherapy. Hemoglobin and neutrophil counts at the conclusion of chemoradiation were associated with OS and PFS on univariate and multivariate analyses. The HR for OS were 0.74 (95% CI 0.5807-0.9313) and 1.28 (1.143-1.441) respectively. The HR for PFS were 0.70 (0.5531-0.8881) and 1.16 (1.05-1.271) respectively. Postoperative lymphocyte and platelet counts at initiation of chemoradiation were both associated with OS with unadjusted HR of 3.2 (1.037-9.960) and HR of 0.99 (0.9898-0.9999) respectively, which remained significant on multivariate analysis. However, neither were associated with PFS.

CONCLUSION

Several hematologic parameters are associated with glioblastoma outcomes in these initial analyses. Further analyses with additional patients are ongoing.

Using the Systemic Immune-Inflammation Index (SII) as a Mid-Treatment Marker for Survival among Patients with Stage-III Locally Advanced Non-Small Cell Lung Cancer (NSCLC)

The Systemic Immune-Inflammation Index (SII) is an important marker of immune function, defined as the product of neutrophil-to-lymphocyte ratio (NLR) and platelet count (P). Higher baseline SII levels have been associated with improved survival in various types of cancers, including lung cancer. Data were obtained from PROCLAIM, a randomized phase III trial comparing two different chemotherapy regimens pemetrexed + cisplatin (PEM) vs. etoposide + cisplatin (ETO), in combination with radiotherapy (RT) for the treatment of stage III non-squamous non-small cell lung cancer (NSCLC). We aimed to determine if SII measured at the mid-treatment window for RT (weeks 3-4) is a significant predictor of survival, and if the effect of PEM vs. ETO differs by quartile (Q) level of SII. Hazard-ratios (HR) for survival were estimated using a proportional hazards model, accounting for the underlying correlated structure of the data. A total of 548 patients were included in our analysis. The median age at baseline was 59 years. Patients were followed for a median of 24 months. Adjusting for age, body mass index, sex, race, and chemotherapy regimen, SII was a significant mid-treatment predictor of both overall (adjusted HR (aHR) = 1.6, p < 0.0001; OS) and progression-free (aHR = 1.3, p = 0.0072; PFS) survival. Among patients with mid-RT SII values above the median (6.8), those receiving PEM (vs. ETO) had superior OS (p = 0.0002) and PFS (p = 0.0002). Our secondary analysis suggests that SII is an informative mid-treatment marker of OS and PFS in locally advanced non-squamous NSCLC.

Final results of a dose escalation protocol of stereotactic body radiotherapy for poor surgical candidates with localized renal cell carcinoma

BACKGROUND AND PURPOSE

We previously demonstrated the safety of doses up to 48 Gy in 4 fractions with stereotactic body radiotherapy (SBRT) in poor surgical candidates with localized renal cell carcinoma (RCC). In an additional expansion cohort, we aimed to assess the safety of further dose escalation to 48-60 Gy in 3 fractions.

MATERIAL AND METHODS

Patients were required to have localized RCC and be poor surgical candidates due to medical comorbidities. Dose-limiting toxicity (DLT) was defined as acute (<180 days) grade ≥3 gastrointestinal/genitourinary toxicity by CTCAEv4. Tumor response was assessed using RECIST 1.1 criteria measurements every 6 months for 3 years and optional percutaneous biopsy.

RESULTS

Groups of 4, 4, and 3 patients received 48, 54, and 60 Gy in 3 fractions, respectively from 2012 to 2016. Median follow-up was 34.3 months. Zero DLTs were observed. Acute toxicities were limited to grade 1 fatigue and nausea in 45.5% and 18.1%. Late grade 2+ and grade 3+ possibly treatment-related events occurred in 18.1% and 9.1%, respectively. Three-year local control was 90% by RECIST 1.1 criteria. Five of 5 post-treatment biopsies in the expansion cohort were positive by Hematoxylin and Eosin staining. Three of the 5 patients with positive biopsies have been observed for 1.2-3.9 years without evidence of progression.

CONCLUSION

Dose escalation to 60 Gy in 3 fractions was achieved without DLTs. Favorable local control rates were observed, and the interpretation of post-SBRT biopsies remains uncertain. Further studies comparing SBRT to percutaneous ablation for poor surgical candidates with RCC are warranted.

Association of metabolic syndrome with glioblastoma: a retrospective cohort study and review

Background

Metabolic syndrome is identified as a risk factor for the development of several systemic cancers, but its frequency among patients with glioblastoma and its association with clinical outcomes have yet to be determined. The aim of this study was to investigate metabolic syndrome as a risk factor for and affecting survival in glioblastoma patients.

Methods

A retrospective cohort study, consisting of patients with diagnoses at a single institution between 2007 and 2013, was conducted. Clinical records were reviewed, and clinical and laboratory data pertaining to 5 metabolic criteria were extrapolated. Overall survival was determined by time from initial surgical diagnosis to date of death or last follow-up.

Results

The frequency of metabolic syndrome among patients diagnosed with glioblastoma was slightly greater than the frequency of metabolic syndrome among the general population. Within a subset of patients (n = 91) receiving the full schedule of concurrent radiation and temozolomide and adjuvant temozolomide, median overall survival was significantly shorter for patients with metabolic syndrome compared with those without. In addition, the presence of all 5 elements of the metabolic syndrome resulted in significantly decreased median survival in these patients.

Conclusions

We identified the metabolic syndrome at a slightly higher frequency in patients with diagnosed glioblastoma compared with the general population. In addition, metabolic syndrome with each of its individual components is associated with an overall worse prognosis in patients receiving the standard schedule of radiation and temozolomide after adjustment for age.

Reirradiation for Recurrent Scalp Angiosarcoma: Dosimetric Advantage of PBT over VMAT and EBT

Purpose

Reirradiation in the scalp area can be challenging given the proximity to organs at risk (OARs), such as the eye and brain. Our aim is to evaluate the dosimetric differences of volumetric modulated arc therapy (VMAT) and electron beam therapy (EBT) compared with 3-dimensional proton beam therapy (PBT).

Patients and Methods

We evaluated a patient with recurrent angiosarcoma of the left temporal scalp after prior surgical resections and radiation therapy to 60 Gy in 30 fractions who needed reirradiation. We generated VMAT, EBT, and PBT plans using the Pinnacle Treatment Planning System (TPS). Both VMAT and EBT plans used a skin bolus, whereas no bolus was used for the proton plan. Doses to the OARs, including cochlea, eyes, lens, lacrimal glands, optic nerves, optic chiasm, pituitary gland, and underlying brain, were compared.

Results

The reirradiation treatment dose was 60 Gy(RBE). Target volume coverage was comparable in all plans. Compared with VMAT and EBT, the PBT plan showed reductions in mean and maximum doses to all OARs. Without the use of protons, several OARs would have exceeded dose tolerance utilizing VMAT or electrons. Dose reduction of up to 100% was achieved for central and contralateral OARs.

Conclusion

Compared with VMAT and EBT, PBT resulted in dose reductions to all OARs, while maintaining excellent target coverage. PBT showed a significant advantage in treating superficially located skin cancers, such as angiosarcoma, without the need for a bolus. PBT can be considered in the upfront treatment and certainly in the reirradiation setting.

Central Airway Toxicity After High Dose Radiation: A Combined Analysis of Prospective Clinical Trials for Non-Small Cell Lung Cancer

PURPOSE

To study the dosimetric risk factors for radiation-induced proximal bronchial tree (PBT) toxicity in patients treated with radiation therapy for non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Patients with medically inoperable or unresectable NSCLC treated with conventionally fractionated 3-dimensional conformal radiation therapy (3DCRT) in prospective clinical trials were eligible for this study. Proximal bronchial tree (PBT) and PBT wall were contoured consistently per RTOG 1106 OAR-Atlas. The dose-volume histograms (DVHs) of physical prescription dose (DVHp) and biological effective dose (α/β = 2.5; DVH2.5) were generated, respectively. The primary endpoint was PBT toxicities, defined by CTCAE 4.0 under the terminology of bronchial stricture/atelectasis.

RESULTS

Of 100 patients enrolled, with a median follow-up of 64 months (95% confidence interval [CI], 50-78), 73% received 70 Gy or greater and 17% developed PBT toxicity (grade 1, 8%; grade 2, 6%; grade 3, 0%; and grade 4, 3%). The median time interval between RT initiation and onset of PBT toxicity was 8.4 months (95% CI, 4.7-44.1). The combined DVHs showed that no patient with a PBT maximum physical dose <65 Gy developed any PBT toxicity. Cox proportional hazards analysis and receiver operating characteristic analysis demonstrated that V75 of PBT was the most significant dosimetric parameter for both grade 1+ (P = .035) and grade 2+ (P = .037) PBT toxicities. The dosimetric thresholds for V75 of PBT were 6.8% and 11.9% for grade 1+ and grade 2+ PBT toxicity, respectively.

CONCLUSIONS

V75 of PBT appeared be the most significant dosimetric parameter for PBT toxicity after conventionally fractionated thoracic 3DCRT. Constraining V75 of PBT can limit clinically significant PBT toxicity.

Changes of plasma GARP-LTGFβ1 complex during chemoradiotherapy may predict survival in non-small cell lung cancer (NSCLC)

e21042

Background: Glycoprotein-A repetitions predominant protein (GARP), a cell surface docking and activating receptor for latent transforming growth factor β1 (LTGFβ1), has been implicated in promoting oncogenesis. We report recently that GARP-LTGFβ can be clipped by thrombin but its clinical significance remains unclear. Herein, we hypothesized that 1) the baseline plasma GARP-LTGFβ1 complex is associated with clinical stage of cancers; 2) the baseline and/or changes of plasma GARP-LTGFβ1 complex during chemo-radiotherapy is associated with overall survival (OS) in patients with NSCLC. Methods: This is a correlative study for patients with stage I-III NSCLC receiving chemo-radiotherapy. Levels of GARP-LTGFβ1 complex in platelet-poor plasma were determined by a modified ELISA at pre-RT, 2,4 weeks during-RT and post-RT. Values were calculated based on the following formula: (ODtest-ODnegative control)/ODpostive control-ODnegative control). The primary endpoint was OS, analyzed using the Kaplan-Meier method and Cox proportional hazard model. Platelet-poor plasma samples from healthy subjects were used as normal controls. Results: A total of 155 patients were included: 41 stage I-II, 111 stage III. There were 115 male, 50 female with a median age of 66 years. Compared to 13 normal controls (0.638, 95% CI:0.477-0.799), NSCLC patients had a significantly higher plasma GARP-LTGFβ1 (0.965, 95%CI: 0.881-1.048, p = 0.014). The same trend was observed for stage, higher level in more advanced stage (1.037, 95%CI: 0.930-1.145) vs for stage I-II (0.854, 95%CI: 0.720-0.988) (p = 0.0375). Univariate analysis demonstrated that age, gender, clinical stage, smoking history, histology, KPS, and radiation dose were significantly associated with OS. Post/pre RT GARP-LTGFβ1 complex (high vs. low HR = 0.384, p = 0.043) instead of pre-RT (p = 0.538), during RT (p = 0.739 for 2 weeks, p = 0.570 for 4 weeks) or post-RT (p = 0.507) plasma GARP-LTGFβ1 complex during the course of radiation therapy correlated significantly with OS under univariate analysis. On multivariate Cox regression models after adjusting for above significant clinical factors, the changes of plasma GARP-LTGFβ1 level had significance in correlating with OS (HR = 0.359, p = 0.0087). Conclusions: Baseline plasma GARP-LTGFβ1 were significantly associated with presence of cancer and advanced stages in NSCLC patients. Changes of GARP-LTGFβ1 level in plasma could be useful to predict outcomes and reflect the changes of immune status after chemoradiation.

Base excision repair (BER) inhibitor TRC 102 (Methoxyamine) combined with pemetrexed (PEM)-based chemo-radiation (CRT) for locally advanced non-squamous non-small cell lung cancer (NS-NSCLC): Results of a phase I trial

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Background: About 35% of all NSCLC presents with locally advanced disease and chemo-radiation results in 5-year OS of only ~31%. PEM-platinum combination is approved in stage IV NSCLC and has similar efficacy to platinum-etoposide in stage 3 NSCLC and a favorable toxicity profile (Proclaim trial). TRC102 is an oral small molecule inhibitor of BER. TRC102 potentiates the cytotoxicity of antimetabolites and alkylators and reverses chemotherapy resistance by rapidly and covalently binding to chemotherapy-induced abasic sites in DNA. TRC102 increased radio-sensitization by PEM of NSCLC cell lines and H1299 and A549 xenografts. Methods: Between 11/2015 and 5/2019, 15 patients were enrolled in a 3+ 3 design: 12 with stage III and 3 with oligometastatic stage IV NS-NSCLC. The primary objective was to determine dose-limiting toxicities (DLT’s) and recommended Phase 2 dose (RP2D) of TRC102 in combination with PEM, cisplatin and radiotherapy. Secondary objectives were to assess toxicity, tumor response and PFS at 6 months. Based on pre-clinical data, PEM-TRC102 was given on day 1, and cisplatin/radiotherapy was initiated on day 3. This schedule was duplicated on day 21 and day 23 of the second cycle. After completion of radiotherapy, two additional cycles of PEM-cisplatin were given. Toxicities were assessed by NCI CTACAE version 4 and 5. Results: Median patient age was 69 years (45-79) and median follow up was 16.6 months (3.1-38.6). There were no DLTs or grade 5 toxicity. Hematologic and GI toxicities were the most common adverse events (Table) and radiation pneumonitis was not seen. The RP2D of TRC102 was 200 mg when given with cisplatin/radiotherapy and PEM. Of 15 evaluable patients, 3 had CR (20%) and 12 had PR (80%). The 2-year PFS rate was 49%. Conclusions: PEM-TRC102 combined with cisplatin/radiotherapy in non-squamous NSCLC was safe and well tolerated, and did not cause safety signals beyond those expected from CRT. Preliminary response data and PFS in this cohort was encouraging. A phase 2 trial, integrating post-CRT immunotherapy with this aggressive DNA-damaging regimen is warranted. Clinical trial information: NCT02535325. [Table: see text]

Ultra-high dose rate effect on circulating immune cells: A potential mechanism for FLASH effect?

PURPOSE

"FLASH" radiotherapy (RT) is a potential paradigm-changing RT technology with marked tumor killing and normal tissue sparing. However, the mechanism of the FLASH effect is not well understood. We hypothesize that the ultra-high dose rate FLASH-RT significantly reduces the killing of circulating immune cells which may partially contribute to the reported FLASH effect.

METHODS

This computation study directly models the effect of radiation dose rate on the killing of circulating immune cells. The model considers an irradiated volume that takes up A% of cardiac output and contains B% of total blood. The irradiated blood volume and dose were calculated for various A%, B%, blood circulation time, and irradiation time (which depends on the dose rate). The linear-quadratic model was used to calculate the extent of killing of circulating immune cells at ultra-high vs. conventional dose rates.

RESULTS

A strong sparing effect on circulating blood cells by FLASH-RT was noticed; i.e., killing of circulating immune cells reduced from 90% to 100% at conventional dose rates to 5-10% at ultra-high dose rates. The threshold FLASH dose rate was determined to be ~40 Gy/s for mice in an average situation (A% = 50%), consistent with the reported FLASH dose rate in animal studies, and it was approximately one order of magnitude lower for humans than for mice. The magnitude of this sparing effect increased with the dose/fraction, reached a plateau at 30-50 Gy/fraction, and almost completely vanished at 2 Gy/fraction.

CONCLUSION

We have calculated a strong sparing effect on circulating immune cells by FLASH-RT, which may contribute to the reported FLASH effects in animal studies.

Delayed response to proton beam treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has become one of the leading causes of cancer death worldwide. There has been anecdotal report regarding the effectiveness of proton beam treatment for HCC. In this pre-clinical investigation, the woodchuck model of viral hepatitis infection-induced HCC was used for proton beam treatment experiment. The radiopaque fiducial markers that are biodegradable were injected around the tumor under ultrasound guidance to facilitate positioning in sequential treatments. An α cradle mode was used to ensure reproducibility of animal positioning on the treatment couch. A CT scan was performed first for contouring by a radiation oncologist. The CT data set with contours was then exported for dose planning. Three fractionations, each 750 CcGyE, were applied every other day with a Mevion S250 passive scattering proton therapy system. Multiphase contrast-enhanced CT scans were performed after the treatment and at later times for follow-ups. 3 weeks post-treatment, shrinking of the HCC nodule was detected and constituted to a partial response (30% reduction along the long axis). By week nine after treatment, the nodule disappeared during the arterial phase of multiphase contrast-enhanced CT scan. Pathological evaluation corroborated with this imaging response. A delayed, but complete imaging response to proton beam treatment applied to HCC was achieved with this unique and clinically relevant animal model of HCC.

An Integrated Framework Based on Full Monte Carlo Simulations for Double-Scattering Proton Therapy

PURPOSE

We developed an integrated framework that employs a full Monte Carlo (MC) model for treatment-plan simulations of a passive double-scattering proton system.

MATERIALS AND METHODS

We have previously validated a virtual machine source model for full MC proton-dose calculations by comparing the percentage of depth-dose curves, spread-out Bragg peaks, and lateral profiles against measured commissioning data. This study further expanded our previous work by developing an integrate framework that facilitates its clinical use. Specifically, we have (1) constructed patient-specific applicator and compensator numerically from the plan data and incorporated them into the beamline, (2) created the patient anatomy from the computed tomography image and established the transformation between patient and machine coordinate systems, and (3) developed a graphical user interface to ease the whole process from importing the treatment plan in the Digital Imaging and Communications in Medicine format to parallelization of the MC calculations. End-to-end tests were performed to validate the functionality, and 3 clinical cases were used to demonstrate clinical utility of the framework.

RESULTS

The end-to-end tests demonstrated that the framework functioned correctly for all tested functionality. Comparisons between the treatment planning system calculations and MC results in 3 clinical cases revealed large dose difference up to 17%, especially in the beam penumbra and near the end of beam range. The discrepancy likely originates from a variety of sources, such as the dose algorithms, modeling of the beamline, and the dose metric. The agreement for other regions was acceptable.

CONCLUSION

An integrated framework was developed for full MC simulations of double-scattering proton therapy. It can be a valuable tool for dose verification and plan evaluation.

Higher Doses of Neoadjuvant Radiation for Esophageal Cancer Do Not Affect the Pathologic Complete Response Rate or Survival: A Propensity-Matched Analysis

BACKGROUND

Traditional neoadjuvant therapy for esophageal cancer has used chemoradiation doses greater than 45 Gy. This study aimed to examine the dose of preoperative radiation in relation to the pathologic complete response (pCR) rate and overall survival (OS) for patients with resectable esophageal cancer.

METHODS

The National Cancer Database was queried for all patients with esophageal or gastroesophageal junction cancer who received neoadjuvant chemoradiation (CRT) followed by esophagectomy between 2006 and 2015. The radiation doses were divided into four ranges based on Grays (Gy) received: less than 39.6 Gy, 39.60-44.99 Gy, 45-49.99 Gy, and 50 Gy or more.

RESULTS

The inclusion criteria were met by 10,293 patients. All patients received neoadjuvant CRT, with 689 patients (6.7%) receiving less than 39.6 Gy, 973 patients (9.5%) receiving 39.6-44.9 Gy, 3837 patients (37.3%) receiving 45-49.9 Gy, and 4794 patients (46.6%) receiving 50 Gy or more. The overall pCR rate was 17.2% (1769/10,293) and was significantly lower for those who received less than 39.6 Gy of radiation than for those who received 39.6 Gy or more (13.9% [96/689] vs. 17.4% [1673/9604]; p = 0.017). The median OS of 37.2 months was significantly better for those who received 39.6 Gy or more than for those who received less than 39.6 Gy (38 vs. 29.6 months (p < 0.0001). The pCR and OS did not differ between the three higher radiation doses (39.6-44.9 vs. 45-49.9 Gy vs. ≥ 50 Gy; pCR [p = 0.1] vs. OS [p = 0.097]). The patients who received 39.6-44.9 Gy were propensity matched with those who received 45 Gy or more of radiation. There remained no difference in pCR (p = 0.375) or OS (p = 0.957).

CONCLUSIONS

In the United States, the heterogeneity in neoadjuvant CRT dosing is significant, with 84% of patients receiving more than 45 Gy. The benefit of neoadjuvant CRT in terms of pCR and overall  survival is seen with doses of 39.6 Gy or more, but not with doses higher than 45 Gy.