Citations

Background: We hypothesized that the Effective radiation Dose to the Immune Cells (EDIC) in circulating blood is a significant factor for the treatment outcome in patients with locally advanced non-small-cell lung cancer (NSCLC). Methods: This is a secondary study of a phase III trial, NRG/RTOG 0617, in patients with stage III NSCLC treated with radiation-based treatment. The EDIC was computed as equivalent uniform dose to the entire blood based on radiation doses to all blood-containing organs, with consideration of blood flow and fractionation effect. The primary endpoint was overall survival (OS), and the secondary endpoints were progression-free survival (PFS) and local progression-free survival (LPFS). The EDIC–survival relationship was analyzed with consideration of clinical significant factors. Results: A total of 456 patients were eligible. The median EDIC values were 5.6 Gy (range, 2.1–12.2 Gy) and 6.3 Gy (2.1–11.6 Gy) for the low- and high-dose groups, respectively. The EDIC was significantly associated with OS (hazard ratio [HR] = 1.12, p = 0.005) and LPFS (HR = 1.09, p = 0.02) but PFS (HR = 1.05, p = 0.17) after adjustment for tumor dose, gross tumor volume and other factors. OS decreased with an increasing EDIC in a non-linear pattern: the two-year OS decreased first with a slope of 8%/Gy when the EDIC < 6 Gy, remained relatively unchanged when the EDIC was 6–8 Gy, and followed by a further reduction with a slope of 12%/Gy when the EDIC > 8 Gy. Conclusions: The EDIC is a significant independent risk factor for poor OS and LPFS in RTOG 0617 patients with stage III NSCLC, suggesting that radiation dose to circulating immune cells is critical for tumor control. Organ at risk for the immune system should be considered during RT plan.

AbstractPurposeDue to the employment of quadratic programming using soft constraints to implement dose volume constraints and the “trial‐and‐error” procedure needed to achieve a clinically acceptable plan, conventional dose volume constraints (upper limit) are not adequately effective in controlling small and isolated hot spots in the dose/linear energy transfer (LET) distribution. Such hot spots can lead to adverse events. In order to mitigate the risk of brain necrosis, one of the most clinically significant adverse events in patients receiving intensity‐modulated proton therapy (IMPT) for base of skull (BOS) cancer, we propose per‐voxel constraints to minimize hot spots in LET‐guided robust optimization.Methods and materialsTen BOS cancer patients treated with IMPT were carefully selected by meeting one of the following conditions: (1) diagnosis of brain necrosis during follow‐up; and (2) considered high risk for brain necrosis by not meeting dose constraints to the brain. An optimizing structure (BrainOPT) and an evaluating structure (BrainROI) that both contained the aforementioned hot dose regions in the brain were generated for optimization and evaluation, respectively. Two plans were generated for every patient: one using conventional dose‐only robust optimization, the other using LET‐guided robust optimization. The impact of LET was integrated into the optimization via a term of extra biological dose (xBD). A novel optimization tool of per‐voxel constraints to control small and isolated hot spots in either the dose, LET, or combined (dose/LET) distribution was developed and used to minimize dose/LET hot spots of the selected structures. Indices from dose‐volume histogram (DVH) and xBD dose‐volume histogram (xBDVH) were used in the plan evaluation. A newly developed tool of the dose‐LET‐volume histogram (DLVH) was also adopted to illustrate the underlying mechanism. Wilcoxon signed‐rank test was used for statistical comparison of the DVH and xBDVH indices between the conventional dose‐only and the LET‐guided robustly optimized plans.ResultsPer‐voxel constraints effectively and efficiently minimized dose hot spots in both dose‐only and LET‐guided robust optimization and LET hot spots in LET‐guided robust optimization. Compared to the conventional dose‐only robust optimization, the LET‐guided robust optimization could generate plans with statistically lower xBD hot spots in BrainROI (VxBD,50 Gy[RBE], p = 0.009; VxBD,60 Gy[RBE], p = 0.025; xBD1cc, p = 0.017; xBD2cc, p = 0.022) with comparable dose coverage, dose hot spots in the target, and dose hot spots in BrainROI. DLVH analysis indicated that LET‐guided robust optimization could either reduce LET at the same dose level or redistribute high LET from high dose regions to low dose regions.ConclusionPer‐voxel constraint is a powerful tool to minimize dose/LET hot spots in IMPT. The LET‐guided robustly optimized plans outperformed the conventional dose‐only robustly optimized plans in terms of xBD hot spots control.

Abstract Purpose The multiple energy extraction (MEE) delivery technique for synchrotron‐based proton delivery systems reduces beam delivery time by decelerating the beam multiple times during one accelerator spill, but this might cause additional plan quality degradation due to intrafractional motion. We seek to determine whether MEE causes significantly different plan quality degradation compared to single energy extraction (SEE) for lung cancer treatments due to the interplay effect. Methods Ten lung cancer patients treated with IMPT at our institution were nonrandomly sampled based on a representative range of tumor motion amplitudes, tumor volumes, and respiratory periods. Dose‐volume histogram (DVH) indices from single‐fraction SEE and MEE four‐dimensional (4D) dynamic dose distributions were compared using the Wilcoxon signed‐rank test. Distributions of monitor units (MU) to breathing phases were investigated for features associated with plan quality degradation. SEE and MEE DVH indices were compared in fractionated deliveries of the worst‐case patient treatment scenario to evaluate the impact of fractionation. Results There were no clinically significant differences in target mean dose, target dose conformity, or dose to organs‐at‐risk between SEE and MEE in single‐fraction delivery. Three patients had significantly worse dose homogeneity with MEE compared to SEE (single‐fraction mean D 5% ‐D 95% increased by up to 9.6% of prescription dose), and plots of MU distribution to breathing phases showed synchronization patterns with MEE but not SEE. However, after 30 fractions the patient in the worst‐case scenario had clinically acceptable target dose homogeneity and coverage with MEE (mean D 5% –D 95% increased by 1% compared to SEE). Conclusions For some patients with breathing periods close to the mean spill duration, MEE resulted in significantly worse single‐fraction target dose homogeneity compared to SEE due to the interplay effect. However, this was mitigated by fractionation, and target dose homogeneity and coverage were clinically acceptable after 30 fractions with MEE.

8569 Background: Immune checkpoint inhibitor (atezolizumab or durvalumab) combined with platinum-etoposide is the standard first-line therapy for patients with extensive-stage small cell lung cancer (ES-SCLC). The phase III clinical trials that led to the approval of chemoimmunotherapy in ES-SCLC, excluded patients with an Eastern Cooperative Group (ECOG) Performance Status (PS) of Two or Greater. Therefore, data on efficacy of this combination in this subgroup of ES-SCLC patients whose performance status two or greater is limited. Methods: A retrospective analysis was performed of patients diagnosed with ES-SCLC who received chemoimmunotherapy (atezolizumab or durvalumab) within the Mayo Clinic Health System between January 2016 and January 2021. Cases were identified from clinical databases at Mayo Clinic. Data on demographics, ECOG-PS, date of diagnosis, date of progression, whole brain radiation, CNS involvement, liver involvement, stereotactic body radiation, chest consolidation, platinum sensitivity, lines of therapy and last follow up date were extracted. Overall Survival (OS) and progression free survival (PFS) for ECOG-PS 2-3 were compared to patients with an ECOG-PS 0-1. Results: A total of 84 patients were identified with a median age of 68.2 (48-88) years old. Of these, 54 patients were identified with an ECOG-PS 0-1 and 30 patients with an ECOG-PS 2-3. The median PFS for the ECOG PS 0-1 cohort was 5.2 months (95% CI 4.6-6.1) while the median PFS for the ECOG-PS 2-3 cohort was 6.0 months (95% CI 4.2-7.7; logrank p = 0.93). The median OS for the ECOG-PS 0-1 cohort was 10.8 months (95% CI 8.5-12.9) while the median OS for the ECOG-PS 2-3 cohort was 10.3 months (95% CI 6.0-14.1; logrank p = 0.39). Hazard ratios of ECOG-PS 0-1 versus 2-3 showed no tendency of increased PFS or OS for either group within cox proportional hazards models. Forty-three percent of ECOG-PS 0-1 achieved a partial response (PR) and 57% of patients who had ECOG-PS 2-3 also achieved a PR (Fisher’s exact p = 0.23). A complete response was found in 4% of ECOG-PS 0-1 compared to 3% in the ECOG-PS 2-3 cohort. For patients who responded to initial therapy, 46% of ECOG-PS 2-3 patients had a platinum sensitive relapse while only 33% of ECOG-PS 0-1 were still platinum sensitive at the time of relapse. Five ECOG-PS 2-3 patients were able to receive a second-line therapy. Conclusions: To our knowledge, this is the first study to evaluate chemoimmunotherapy in the subgroup of ES-SCLC patients with an ECOG-PS 2 or greater. This retrospective study demonstrated no significant difference in PFS, OS, and ability to achieve a least a PR in ECOG-PS 2-3 cohort when compared to ECOG-PS 0-1. Therefore, chemoimmunotherapy should not be reserved for only an ECOG-PS of 0-1 but should be considered for all treatment eligible patients.

Abstract Background Pineoblastoma (PB) is a rare embryonal brain tumour most often diagnosed in young children. To date, no clinical trials have been conducted specific to pediatric PB. Collaborative studies performed over the past 30 years have included PB in studies accruing for other embryonal tumours, primarily medulloblastoma (MB), but also including the entity formerly known as CNS-PNET and atypical teratoid rhabdoid tumors. Each of these studies have included only a small number of children with PB, making clinical features difficult to interpret and determinants of outcome difficult to ascertain. Patients and Methods Published centrally reviewed series with sufficient treatment and outcome data from North American and Australian cases were pooled. To investigate associations between variables, Fisher’s exact and Wilcoxon-Mann-Whitney tests, and Spearman correlations were used as appropriate. Kaplan-Meier plots, log-rank tests, and Cox proportional hazards models were used in survival analysis. Results We describe a 30-year review of the reported clinical features of PB and a pooled centrally reviewed, cohort analysis of cases (n=178) from the Children’s Oncology Group (COG) (n=82) groups and several published, centrally reviewed institutional series (n=96). We find young children &lt;3 years of age have a dramatically poorer outlook compared to older children (5-year OS 16.2% +/- 5.3% vs 67.3% +/- 5%) confirming new and novel approaches are needed in future clinical trials for this at risk group. Interestingly, male gender was predictive of worse outcome possibly suggestive of gender specific subgroup risks that needs validation in future studies. Assessment of radiation therapy is not possible as the vast majority of children under age three did not receive any form of radiation therapy. Conclusion Given the relative scarcity of this tumor and the emerging data on subgroups of pineoblastoma, prospective, collaborative international studies will be vital to improving the long-term survival of these patients.

Purpose To compare the dosimetric performances of small‐spot three‐dimensional (3D) and four‐dimensional (4D) robustly optimized intensity‐modulated proton (IMPT) plans in the presence of uncertainties and interplay effect simultaneously for distal esophageal carcinoma. Method and Materials Thirteen (13) patients were selected and re‐planned with small‐spot ( ~ 2–6 mm) 3D and 4D robust optimization in IMPT, respectively. The internal clinical target volumes (CTV high3d , CTV low3d ) were used in 3D robust optimization. Different CTVs (CTV high4d , CTV low4d ) were generated by subtracting an inner margin of the motion amplitudes in three cardinal directions from the internal CTVs and used in 4D robust optimization. All patients were prescribed the same dose to CTVs (50 Gy[RBE] for CTV high3d /CTV high4d and 45 Gy[RBE] for CTV low3d /CTV low4d ). Dose–volume histogram (DVH) indices were calculated to assess plan quality. Comprehensive plan robustness evaluations that consisted of 300 perturbed scenarios (10 different motion patterns to consider irregular motion (sampled from a Gaussian distribution) and 30 different uncertainties scenarios (sampled from a 4D uniform distribution) combined), were performed to quantify robustness to uncertainties and interplay effect simultaneously. Wilcoxon signed‐rank test was used for statistical analysis. Results Compared to 3D robustly optimized plans, 4D robustly optimized plans had statistically improved target coverage and better sparing of lungs and heart (heart D mean , P = 0.001; heart V 30Gy[RBE] , P = 0.001) in the nominal scenario. 4D robustly optimized plans had better robustness in target dose coverage (CTV high4d V 100% , P = 0.002) and the protection of lungs and heart (heart D mean , P = 0.001; heart V 30Gy[RBE] , P = 0.001) when uncertainties and interplay effect were considered simultaneously. Conclusions Even with small spots in IMPT, 4D robust optimization outperformed 3D robust optimization in terms of normal tissue protection and robustness to uncertainties and interplay effect simultaneously. Our findings support the use of 4D robust optimization to treat distal esophageal carcinoma with small spots in IMPT.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Non–Small Cell Lung Cancer (NSCLC) address all aspects of management for NSCLC. These NCCN Guidelines Insights focus on recent updates to the NCCN Guidelines regarding targeted therapies, immunotherapies, and their respective biomarkers.

Abstract Purpose To compare the dosimetric performances of intensity‐modulated proton therapy (IMPT) plans generated with two different beam angle configurations (the Right–Left oblique posterior beams and the Superior–Inferior oblique posterior beams) for the treatment of distal esophageal carcinoma in the presence of uncertainties and interplay effect. Methods and Materials Twenty patients’ IMPT plans were retrospectively selected, with 10 patients treated with the R‐L oblique posterior beams (Group R‐L) and the other 10 patients treated with the S‐I oblique posterior beams (Group S‐I). Patients in both groups were matched by their clinical target volumes (CTVs—high and low dose levels) and respiratory motion amplitudes. Dose‐volume‐histogram (DVH) indices were used to assess plan quality. DVH bandwidth was calculated to evaluate plan robustness. Interplay effect was quantified using four‐dimensional (4D) dynamic dose calculation with random respiratory starting phase of each fraction. Normal tissue complication probability (NTCP) for heart, liver, and lung was calculated, respectively, to estimate the clinical outcomes. Wilcoxon signed‐rank test was used for statistical comparison between the two groups. Results Compared with plans in Group R‐L, plans in Group S‐I resulted in significantly lower liver D mean and lung V 30Gy[RBE] with slightly higher but clinically acceptable spinal cord D max . Similar plan robustness was observed between the two groups. When interplay effect was considered, plans in Group S‐I performed statistically better for heart D mean and V 30Gy[RBE] , lung Dmean and V 5Gy[RBE] , and liver D mean , with slightly increased but clinically acceptable spinal cord D max . NTCP for liver was significantly better in Group S‐I. Conclusions IMPT plans in Group S‐I have better sparing of liver, heart, and lungs at the slight cost of spinal cord maximum dose protection, and are more interplay‐effect resilient compared to IMPT plans in Group R‐L. Our study supports the routine use of the S‐I oblique posterior beams for the treatments of distal esophageal carcinoma.

Purpose Intensity‐modulated proton therapy (IMPT) is sensitive to uncertainties from patient setup and proton beam range, as well as interplay effect. In addition, respiratory motion may vary from cycle to cycle, and also from day to day. These uncertainties can severely degrade the original plan quality and potentially affect patient’s outcome. In this work, we developed a new tool to comprehensively consider the impact of all these uncertainties and provide plan robustness evaluation under them. Methods We developed a comprehensive plan robustness evaluation tool that considered both uncertainties from patient setup and proton beam range, as well as respiratory motion simultaneously. To mimic patients' respiratory motion, the time spent in each phase was randomly sampled based on patient‐specific breathing pattern parameters as acquired during the four‐dimensional (4D)‐computed tomography (CT) simulation. Spots were then assigned to one specific phase according to the temporal relationship between spot delivery sequence and patients’ respiratory motion. Dose in each phase was calculated by summing contributions from all the spots delivered in that phase. The final 4D dynamic dose was obtained by deforming all doses in each phase to the maximum exhalation phase. Three hundred (300) scenarios (10 different breathing patterns with 30 different setup and range uncertainty scenario combinations) were calculated for each plan. The dose‐volume histograms (DVHs) band method was used to assess plan robustness. Benchmarking the tool as an application’s example, we compared plan robustness under both three‐dimensional (3D) and 4D robustly optimized IMPT plans for 10 nonrandomly selected patients with non‐small cell lung cancer. Results The developed comprehensive plan robustness tool had been successfully applied to compare the plan robustness between 3D and 4D robustly optimized IMPT plans for 10 lung cancer patients. In the presence of interplay effect with uncertainties considered simultaneously, 4D robustly optimized plans provided significantly better CTV coverage (D 95% , P = 0.002), CTV homogeneity (D 5% ‐D 95% , P = 0.002) with less target hot spots (D 5% , P = 0.002), and target coverage robustness (CTV D 95% bandwidth, P = 0.004) compared to 3D robustly optimized plans. Superior dose sparing of normal lung (lung D mean , P = 0.020) favoring 4D plans and comparable normal tissue sparing including esophagus, heart, and spinal cord for both 3D and 4D plans were observed. The calculation time for all patients included in this study was 11.4 ± 2.6 min. Conclusion A comprehensive plan robustness evaluation tool was successfully developed and benchmarked for plan robustness evaluation in the presence of interplay effect, setup and range uncertainties. The very high efficiency of this tool marks its clinical adaptation, highly practical and versatile nature, including possible real‐time intra‐fractional interplay effect evaluation as a potential application for future use.

e22167 Background: Safe and effective delivery of viral vectors is important for gene therapy. Local application of such vectors is more efficient than systemic application. However, currently available injection systems are not optimal because placement of the injection needle and the vector application itself are generally not reproducibile. We developed a new injection system providing controlled injection of adenoviral vectors in tumors (xeno-transplants) in nude mice (NMRI nu/nu). Methods: The new MAGD consists of two fixation devices mounted on a 40x40cm plexi-glass plate, four injection units, and one pump unit with 4 infusion-pumps (Bee hive, Bioanalytical, Chesire, UK). Each injection unit is linked to a pump with commercially available plastic tube. Because the injection arms can be moved in x-,y- and z-direction, virus injection can easily performed for irregular tumor volumes. The entire injection volume is equally distributed to the 4 injection pumps allowing precise and steady injection rates between 0.1μl/min and 100μl/min. Success was confirmed with MRI-scans (Magnetom symphony, Siemens, Erlangen, Germany) 10 min after the injection. The efficacy of the MAGD was tested in 4 human squamous cell carcinoma cell lines from oro-/hypopharynx (FaDu, UD- SCC2, UD-SCC6, and UD-SCC7a). Virus transfection was performed with an adenovirus (serotype 5) expressing enhanced green fluorescent protein (eGFP). Transfection rates were quantified with flow cytometry. Successfully transfected cells expressed eGFP resulting in green fluorescence. In-vitro cell lines (concentration: 10 particles per cell, MOI 10) of FaDu, UD-SCC2, UD-SCC6 and UD-SCC7a served as controls. Results: The MAGD was easy to handle. Injection of 100μl (25μl per infusion pump) at an injection rate of 5μl/min took only 5 min. The in-vivo transfection rates achieved with the MAGD were 9±1% for FaDu, 39±2% for UD- SCC, 54±1% for UD-SCC6 and 54±9% for UD-SCC7a, respectively. The in-vitro transfection rates (controls) for these 4 cell lines were 2±1%, 23±4%, 29±4% and 3±2%, respectively. Conclusions: The new MAGD provided controlled injection of adenoviral vectors in tumors in nude mice. It proved to be effective, as it resulted in comparably high transfection rates. No significant financial relationships to disclose.