Post-operative complications following dose adaptation of intra-operative electron beam radiation therapy in locally advanced or recurrent rectal cancer.

Purpose: The benefit of intra-operative radiotherapy (IORT) in the treatment of locally advanced rectal cancer (LARC) or locally recurrent rectal cancer (LRRC) lie in its ability to provide high-dose of radiation to limited at-risk volume, thereby eliminating microscopic disease and decreasing toxicity. A comparative study between high-dose-rate (HDR) brachytherapy, named intra-operative brachytherapy (IOBT), and intra-operative electron radiotherapy (IOERT) was performed showing favorable LRFS after IOBT, possibly due to a higher surface dose that is inherent in IOBT technique. The IOERT technique in Catharina Hospital Eindhoven was adapted to increase the surface dose, aiming to improve local control. Post-operative complications due to an increased radiation dose remain the matter of concern. This retrospective study was performed to compare complication rates before and after adapted IOERT dose. Material and methods: All patients undergoing surgery with IOERT for LARC or LRRC from September 2019 until July 2023, were considered. Patients selected until August 31, 2021 were included in control cohort (n = 108), and those chosen from September 1, 2021 onwards were included in intervention cohort (n = 92). Perioperative and (major) post-operative complications were classified retrospectively, during admission, at 30 days, and at 90 days. Results: In LARC patients, a decrease in post-operative complications was observed (p = 0.009). 19% of LARC patients experienced major post-operative surgical complications, i.e., Clavien-Dindo grade 3b-5, regardless of treatment group. No difference in major 90-day complications was noted (p = 0.142). In LRRC patients, the use of induction chemotherapy decreased from 78% to 29% (p < 0.001), which complicated comparison. However, no difference in major post-operative complications was observed at 30 days (p = 0.222) or 90 days (p = 0.977) after surgery. Conclusions: Increased surface dose of IOERT does not seem to lead to an increase in post-operative complications. Further research is needed to evaluate the efficacy of dose adaptation in IOERT to improve local oncological control rates. Routine evaluation of CTCAE scores in follow-up will help uncover possible long-term radiation-induced toxicity.

Dutch national guidelines for locally recurrent rectal cancer.

Due to improvements in treatment for primary rectal cancer, the incidence of LRRC has decreased. However, 6-12% of patients will still develop a local recurrence. Treatment of patients with LRRC can be challenging, because of complex and heterogeneous disease presentation and scarce - often low-grade - data steering clinical decisions. Previous consensus guidelines have provided some direction regarding diagnosis and treatment, but no comprehensive guidelines encompassing all aspects of the clinical management of patients with LRRC are available to date. The treatment of LRRC requires a multidisciplinary approach and overarching expertise in all domains. This broad expertise is often limited to specific expert centres, with dedicated multidisciplinary teams treating LRRC. A comprehensive, narrative literature review was performed and used to develop the Dutch National Guideline for management of LRRC, in an attempt to guide decision making for clinicians, regarding the complete clinical pathway from diagnosis to surgery.

Stereotactic Body Radiotherapy for Centrally Located Inoperable Early-Stage NSCLC: EORTC 22113-08113 LungTech Phase II Trial Results.

INTRODUCTION: The international phase II single-arm LungTech trial 22113-08113 of the European Organization for Research and Treatment of Cancer assessed the safety and efficacy of stereotactic body radiotherapy (SBRT) in patients with centrally located early-stage NSCLC. METHODS: Patients with inoperable non-metastatic central NSCLC (T1-T3 N0 M0, ≤7cm) were included. After prospective central imaging review and radiation therapy quality assurance for any eligible patient, SBRT (8 × 7.5 Gy) was delivered. The primary endpoint was freedom from local progression probability three years after the start of SBRT. RESULTS: The trial was closed early due to poor accrual related to repeated safety-related pauses in recruitment. Between August 2015 and December 2017, 39 patients from six European countries were included and 31 were treated per protocol and analyzed. Patients were mainly male (58%) with a median age of 75 years. Baseline comorbidities were mainly respiratory (68%) and cardiac (48%). Median tumor size was 2.6 cm (range 1.2-5.5) and most cancers were T1 (51.6%) or T2a (38.7%) N0 M0 and of squamous cell origin (48.4%). Six patients (19.4%) had an ultracentral tumor location. The median follow-up was 3.6 years. The rates of 3-year freedom from local progression and overall survival were 81.5% (90% confidence interval [CI]: 62.7%-91.4%) and 61.1% (90% CI: 44.1%-74.4%), respectively. Cumulative incidence rates of local, regional, and distant progression at three years were 6.7% (90% CI: 1.6%-17.1%), 3.3% (90% CI: 0.4%-12.4%), and 29.8% (90% CI: 16.8%-44.1%), respectively. SBRT-related acute adverse events and late adverse events ≥ G3 were reported in 6.5% (n = 2, including one G5 pneumonitis in a patient with prior interstitial lung disease) and 19.4% (n = 6, including one lethal hemoptysis after a lung biopsy in a patient receiving anticoagulants), respectively. CONCLUSIONS: The LungTech trial suggests that SBRT with 8 × 7.5Gy for central lung tumors in inoperable patients is associated with acceptable local control rates. However, late severe adverse events may occur after completion of treatment. This SBRT regimen is a viable treatment option after a thorough risk-benefit discussion with patients. To minimize potentially fatal toxicity, careful management of dose constraints, and post-SBRT interventions is crucial.

Cancer-specific dose and fractionation schedules in stereotactic body radiotherapy for oligometastatic disease: An interim analysis of the EORTC-ESTRO E2-RADIatE OligoCare study.

BACKGROUND AND INTRODUCTION: Optimal dose and fractionation in stereotactic body radiotherapy (SBRT) for oligometastatic cancer patients remain unknown. In this interim analysis of OligoCare, we analyzed factors associated with SBRT dose and fractionation. MATERIALS AND METHODS: Analysis was based on the first 1,099 registered patients. SBRT doses were converted to biological effective doses (BED) using α/ß of 10 Gy for all primaries, and cancer-specific α/ß of 10 Gy for non-small cell lung and colorectal cancer (NSCLC, CRC), 2.5 Gy for breast cancer (BC), or 1.5 Gy for prostate cancer (PC). RESULTS: Of the interim analysis population of 1,099 patients, 999 (99.5 %) fulfilled inclusion criteria and received metastasis-directed SBRT for NSCLC (n = 195; 19.5 %), BC (n = 163; 16.3 %), CRC (n = 184; 18.4 %), or PC (n = 457; 47.5 %). Two thirds of patients were treated for single metastasis. Median number of fractions was 5 (IQR, 3-5) and median dose per fraction was 9.7 (IQR, 7.7-12.4) Gy. The most frequently treated sites were non-vertebral bone (22.8 %), lung (21.0 %), and distant lymph node metastases (19.0 %). On multivariate analysis, the dose varied significantly for primary cancer type (BC: 237.3 Gy BED, PC 300.6 Gy BED, and CRC 84.3 Gy BED), and metastatic sites, with higher doses for lung and liver lesions. CONCLUSION: This real-world analysis suggests that SBRT doses are adjusted to the primary cancers and oligometastasis location. Future analysis will address safety and efficacy of this site- and disease-adapted SBRT fractionation approach (NCT03818503).

Health-related quality of life in men with oligometastatic prostate cancer following metastases-directed stereotactic body radiotherapy: Real-world data from the E2-RADIatE OligoCare cohort.

Objective: To evaluate the impact of metastases-directed stereotactic body radiotherapy (SBRT) on health-related quality of life (HRQoL) in men with oligometastatic prostate cancer (PCa) using real-world data from the OligoCare cohort. Materials and methods: OligoCare is a pragmatic, observational cohort designed to assess the impact of metastases-directed SBRT on patients with oligometastatic disease (OMD). We report an interim analyses of the secondary endpoint HRQoL, assessed using the EORTC QLQ-C30, within six months of metastases-directed SBRT for oligometastatic disease in men with PCa among the first 1600 registered patients. HRQoL data collection was optional within the OligoCare cohort. To compare HRQoL between baseline and first follow-up assessment, a Wilcoxon signed-rank test was used. A multiple linear regression model was used to explore the HRQoL associations with predefined factors. Results: Out of the 1600 registered patients, 658 were treated for oligometastatic PCa, of which 233 had baseline QoL data and 132 patients had both baseline and follow-up HRQoL data. At baseline, most patients had a WHO performance status of 0 or 1 (87 %), were de-novo oligometastatic (79 %), had one metastasis (90 %), and had a good overall global health status (mean 80.81, SD16.11, IQR 75-92). 51 % received hormonal therapy as concomitant systemic treatment. Patients with comorbidities as assessed by the Charlson Comorbidity index had a worse global health status at baseline (-4.88, 95 % CI:-9.35, -0.42). No clinically meaningful significant difference in global health status was observed at first assessment following SBRT (median 3.0 months) compared with baseline (mean difference 2.27, 95 % CI:-1.54, 6.08). Upon evaluating the proportions, meaningful clinically important differences (a 10-point or more difference) was observed in, 17 % and 11 % of the patients reporting deterioration and improvement of global health status, respectively. Conclusion: Metastases-directed stereotactic body radiotherapy had no negative impact on global HRQoL within the first six months after treatment.

Locally recurrent rectal cancer: Oncological outcomes for patients with a pathological complete response after neoadjuvant therapy.

BACKGROUND: For patients with locally recurrent rectal cancer, it is an ongoing pursuit to establish factors predicting or improving oncological outcomes. In locally advanced rectal cancer, a pCR appears to be associated with improved outcomes. The aim of this retrospective cohort study was to compare the oncological outcomes of patients with locally recurrent rectal cancer with and without a pCR. METHODS: Patients who underwent neoadjuvant treatment and surgery for locally recurrent rectal cancer with curative intent between January 2004 and June 2020 at a tertiary referral hospital were analysed. Primary outcomes included overall survival, disease-free survival, metastasis-free survival, and local re-recurrence-free survival, stratified according to whether the patient had a pCR. RESULTS: Of a total of 345 patients, 51 (14.8 per cent) had a pCR. Median follow-up was 36 (i.q.r. 16-60) months. The 3-year overall survival rate was 77 per cent for patients with a pCR and 51.1 per cent for those without (P < 0.001). The 3-year disease-free survival rate was 56 per cent for patients with a pCR and 26.1 per cent for those without (P < 0.001). The 3-year local re-recurrence-free survival rate was 82 and 44 per cent respectively (P < 0.001). Surgical procedures (for example soft tissue, sacrum, and urogenital organ resections) and postoperative complications were comparable between patients with and without a pCR. CONCLUSION: This study showed that patients with a pCR have superior oncological outcomes to those without a pCR. It may therefore be safe to consider a watch-and-wait approach in highly selected patients, potentially improving quality of life by omitting extensive surgical procedures without compromising oncological outcomes.

Metastases-directed stereotactic body radiotherapy in combination with targeted therapy or immunotherapy: systematic review and consensus recommendations by the EORTC-ESTRO OligoCare consortium.

Stereotactic body radiotherapy (SBRT) for patients with metastatic cancer, especially when characterised by a low tumour burden (ie, oligometastatic disease), receiving targeted therapy or immunotherapy has become a frequently practised and guideline-supported treatment strategy. Despite the increasing use in routine clinical practice, there is little information on the safety of combining SBRT with modern targeted therapy or immunotherapy and a paucity of high-level evidence to guide clinical management. A systematic literature review was performed to identify the toxicity profiles of combined metastases-directed SBRT and targeted therapy or immunotherapy. These results served as the basis for an international Delphi consensus process among 28 interdisciplinary experts who are members of the European Society for Radiotherapy and Oncology (ESTRO) and European Organisation for Research and Treatment of Cancer (EORTC) OligoCare consortium. Consensus was sought about risk mitigation strategies of metastases-directed SBRT combined with targeted therapy or immunotherapy; a potential need for and length of interruption to targeted therapy or immunotherapy around SBRT delivery; and potential adaptations of radiation dose and fractionation. Results of this systematic review and consensus process compile the best available evidence for safe combination of metastases-directed SBRT and targeted therapy or immunotherapy for patients with metastatic or oligometastatic cancer and aim to guide today's clinical practice and the design of future clinical trials.

Development of a consensus-based delineation guideline for locally recurrent rectal cancer.

BACKGROUND AND PURPOSE: Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team. MATERIALS AND METHODS: Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed. RESULTS: Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients. CONCLUSION: This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.

Narrowing the difference in dose delivery for IOERT and IOBT for locally advanced and locally recurrent rectal cancer.

Purpose: Intra-operative radiotherapy (IORT) has been used as a tool to provide a high-dose radiation boost to a limited volume of patients with fixed tumors with a likelihood of microscopically involved resection margins, in order to improve local control. Two main techniques to deliver IORT include high-dose-rate (HDR) brachytherapy, termed 'intra-operative brachytherapy' (IOBT), and electrons, termed 'intra-operative electron radiotherapy' (IOERT), both having very different dose distributions. A recent paper described an improved local recurrence-free survival favoring IOBT over IOERT for patients with locally advanced or recurrent rectal cancer and microscopically irradical resections. Although several factors may have contributed to this result, an important difference between the two techniques was the higher surface dose delivered by IOBT. This article described an adaptation of IOERT technique to achieve a comparable surface dose as dose delivered by IOBT. Material and methods: Two steps were taken to increase the surface dose for IOERT: 1. Introducing a bolus to achieve a maximum dose on the surface, and 2. Re-normalizing to allow for the same prescribed dose at reference depth. Conclusions: We describe and propose an adaptation of IOERT technique to increase surface dose, decreasing the differences between these two techniques, with the aim of further improving local control. In addition, an alternative method of dose prescription is suggested, to consider improved comparison with other techniques in the future.

Intraoperative Electron Beam Radiation Therapy (IOERT) Versus High-Dose-Rate Intraoperative Brachytherapy (HDR-IORT) in Patients With an R1 Resection for Locally Advanced or Locally Recurrent Rectal Cancer.

PURPOSE: Intraoperative radiation therapy (IORT), delivered by intraoperative electron beam radiation therapy (IOERT) or high-dose-rate intraoperative brachytherapy (HDR-IORT), may reduce the local recurrence rate in patients with locally advanced and locally recurrent rectal cancer (LARC and LRRC, respectively). The aim of this study was to compare the oncological outcomes between both IORT modalities in patients with LARC or LRRC who underwent a microscopic irradical (R1) resection. METHODS: All consecutive patients who received IORT because of an R1 resection of LARC or LRRC between 2000 and 2016 in two tertiary referral centers were included. In LARC, a resection margin of ≤2 mm was considered R1. A resection margin of 0 mm was considered R1 in LRRC. RESULTS: In total, 215 patients with LARC were included, of whom 151 (70%) received IOERT and 64 (30%) received HDR-IORT; in addition, 158 patients with LRRC were included, of whom 112 (71%) received IOERT and 46 (29%) received HDR-IORT. After multivariable analyses, the overall survival was not significantly different between the two IORT modalities. The local recurrence-free survival was significantly longer in patients treated with HDR-IORT, both in LARC (hazard ratio [HR], 0.496; 95% CI, 0.253-0.973; P = .041) and LRRC (HR, 0.567; 95% CI, 0.349-0.920; P = .021). In patients with LARC, major postoperative complications were similar for both IORT modalities (IOERT, 30%; HDR-IORT, 27%), whereas in patients with LRRC, the incidence of major postoperative complications was higher after HDR-IORT (IOERT, 26%; HDR-IORT, 46%). CONCLUSIONS: This study showed a significantly better local recurrence-free survival in favor of HDR-IORT in patients with an R1 resection for LARC or LRRC. Optimization of the IOERT technique seems warranted.

Phase I and Pharmacologic Study of Olaparib in Combination with High-dose Radiotherapy with and without Concurrent Cisplatin for Non-Small Cell Lung Cancer.

PURPOSE: To identify an MTD of olaparib, a PARP inhibitor, in combination with loco-regional radiotherapy with/without cisplatin for the treatment of non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Olaparib dose was escalated in two groups: radiotherapy (66 Gy/24 fractions in 2.75 Gy/fraction) with and without daily cisplatin (6 mg/m2), using time-to-event continual reassessment method with a 1-year dose-limiting toxicity (DLT) period. The highest dose level with a DLT probability <15% was defined as MTD. Poly ADP-ribose (PAR) inhibition and radiation-induced PAR-ribosylation (PARylation) were determined in peripheral blood mononuclear cells. RESULTS: Twenty-eight patients with loco-regional or oligometastatic disease (39%) were treated: 11 at olaparib 25 mg twice daily and 17 at 25 mg once daily. The lowest dose level with cisplatin was above the MTD due to hematologic and late esophageal DLT. The MTD without cisplatin was olaparib 25 mg once daily. At a latency of 1-2.8 years, severe pulmonary adverse events (AE) were observed in 5 patients across all dose levels, resulting in 18% grade 5 pulmonary AEs. Exploratory analyses indicate an association with the radiation dose to the lungs. At the MTD, olaparib reduced PAR levels by more than 95% and abolished radiation-induced PARylation. Median follow-up of survivors was 4.1 years. Two-year loco-regional control was 84%, median overall survival in patients with locally advanced NSCLC was 28 months. CONCLUSIONS: Combined mildly hypofractionated radiotherapy and low-dose daily cisplatin and olaparib was not tolerable due to esophageal and hematologic toxicity. Severe pulmonary toxicity was observed as well, even without cisplatin. More conformal radiotherapy schedules with improved pulmonary and esophageal sparing should be explored.

Pembrolizumab with or without radiotherapy for metastatic non-small-cell lung cancer: a pooled analysis of two randomised trials.

BACKGROUND: Radiotherapy might augment systemic antitumoral responses to immunotherapy. In the PEMBRO-RT (phase 2) and MDACC (phase 1/2) trials, patients with metastatic non-small-cell lung cancer were randomly allocated immunotherapy (pembrolizumab) with or without radiotherapy. When the trials were analysed individually, a potential benefit was noted in the combination treatment arm. However, owing to the small sample size of each trial, differences in response rates and outcomes were not statistically significant but remained clinically notable. We therefore did a pooled analysis to infer whether radiotherapy improves responses to immunotherapy in patients with metastatic non-small-cell lung cancer. METHODS: Inclusion criteria for the PEMBRO-RT and MDACC trials were patients (aged ≥18 years) with metastatic non-small-cell lung cancer and at least one unirradiated lesion to monitor for out-of-field response. In the PEMBRO-RT trial, patients had previously received chemotherapy, whereas in the MDACC trial, patients could be either previously treated or newly diagnosed. Patients in both trials were immunotherapy-naive. In the PEMBRO-RT trial, patients were randomly assigned (1:1) and stratified by smoking status (<10 vs ≥10 pack-years). In the MDACC trial, patients were entered into one of two cohorts based on radiotherapy schedule feasibility and randomly assigned (1:1). Because of the nature of the intervention in the combination treatment arm, blinding to radiotherapy was not feasible in either trial. Pembrolizumab was administered intravenously (200 mg every 3 weeks) with or without radiotherapy in both trials. In the PEMBRO-RT trial, the first dose of pembrolizumab was given sequentially less than 1 week after the last dose of radiotherapy (24 Gy in three fractions), whereas in the MDACC trial, pembrolizumab was given concurrently with the first dose of radiotherapy (50 Gy in four fractions or 45 Gy in 15 fractions). Only unirradiated lesions were measured for response. The endpoints for this pooled analysis were best out-of-field (abscopal) response rate (ARR), best abscopal disease control rate (ACR), ARR at 12 weeks, ACR at 12 weeks, progression-free survival, and overall survival. The intention-to-treat populations from both trials were included in analyses. The PEMBRO-RT trial (NCT02492568) and the MDACC trial (NCT02444741) are registered with ClinicalTrials.gov. FINDINGS: Overall, 148 patients were included in the pooled analysis, 76 of whom had been assigned pembrolizumab and 72 who had been assigned pembrolizumab plus radiotherapy. Median follow-up for all patients was 33 months (IQR 32·4-33·6). 124 (84%) of 148 patients had non-squamous histological features and 111 (75%) had previously received chemotherapy. Baseline variables did not differ between treatment groups, including PD-L1 status and metastatic disease volume. The most frequently irradiated sites were lung metastases (28 of 72 [39%]), intrathoracic lymph nodes (15 of 72 [21%]), and lung primary disease (12 of 72 [17%]). Best ARR was 19·7% (15 of 76) with pembrolizumab versus 41·7% (30 of 72) with pembrolizumab plus radiotherapy (odds ratio [OR] 2·96, 95% CI 1·42-6·20; p=0·0039), and best ACR was 43·4% (33 of 76) with pembrolizumab versus 65·3% (47 of 72) with pembrolizumab plus radiotherapy (2·51, 1·28-4·91; p=0·0071). Median progression-free survival was 4·4 months (IQR 2·9-5·9) with pembrolizumab alone versus 9·0 months (6·8-11·2) with pembrolizumab plus radiotherapy (hazard ratio [HR] 0·67, 95% CI 0·45-0·99; p=0·045), and median overall survival was 8·7 months (6·4-11·0) with pembrolizumab versus 19·2 months (14·6-23·8) with pembrolizumab plus radiotherapy (0·67, 0·54-0·84; p=0·0004). No new safety concerns were noted in the pooled analysis. INTERPRETATION: Adding radiotherapy to pembrolizumab immunotherapy significantly increased responses and outcomes in patients with metastatic non-small-cell lung cancer. These results warrant validation in a randomised phase 3 trial. FUNDING: Merck Sharp & Dohme.

SBRT combined with concurrent chemoradiation in stage III NSCLC: Feasibility study of the phase I Hybrid trial.

PURPOSE: To assess the technical and clinical feasibility of the phase I Hybrid trial (NCT01933568), combining SBRT of the primary tumor (PT) and fractionated radiotherapy (FRT) to the lymph nodes (LN). MATERIALS AND METHODS: Ten patients with stage III NSCLC with a peripheral PT < 5 cm were prospectively selected. The EQD2 corrected normal tissue dose parameters of the FRT plan of 24×2.75 Gy to PT and 24×2.42 Gy to LN (IMRT) was compared with 3×18 Gy on the PT and 24×2.42 Gy on the LN (VMAT) using a Wilcoxon signed-rank test. To anticipate differential motion between PT and LN, worst-case scenarios for OAR were calculated. Electronic portal imaging device (EPID) dosimetry analysis was performed to rule out dosimetric errors during delivery. RESULTS: The Hybrid plans revealed a significant decrease of esophagus EUD n = 0.13, lung V5 and V20 and a significant increase in Dmax of the PRV of the mediastinal envelope. Plans were robust against differential motion of 5 mm between PT and LN in 8 patients and failed in 2 patients due to spinal cord constraints. Average pass rates were ≥87% for EPID dosimetry. CONCLUSIONS: SBRT and FRT could be combined within the given OAR constraints. Safety will be assessed in the Hybrid trial.

Effect of Pembrolizumab After Stereotactic Body Radiotherapy vs Pembrolizumab Alone on Tumor Response in Patients With Advanced Non-Small Cell Lung Cancer: Results of the PEMBRO-RT Phase 2 Randomized Clinical Trial.

IMPORTANCE: Many patients with advanced non-small cell lung cancer (NSCLC) receiving immunotherapy show primary resistance. High-dose radiotherapy can lead to increased tumor antigen release, improved antigen presentation, and T-cell infiltration. This radiotherapy may enhance the effects of checkpoint inhibition. OBJECTIVE: To assess whether stereotactic body radiotherapy on a single tumor site preceding pembrolizumab treatment enhances tumor response in patients with metastatic NSCLC. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, randomized phase 2 study (PEMBRO-RT) of 92 patients with advanced NSCLC enrolled between July 1, 2015, and March 31, 2018, regardless of programmed death-ligand 1 (PD-L1) status. Data analysis was of the intention-to-treat population. INTERVENTIONS: Pembrolizumab (200 mg/kg every 3 weeks) either alone (control arm) or after radiotherapy (3 doses of 8 Gy) (experimental arm) to a single tumor site until confirmed radiographic progression, unacceptable toxic effects, investigator decision, patient withdrawal of consent, or a maximum of 24 months. MAIN OUTCOMES AND MEASURES: Improvement in overall response rate (ORR) at 12 weeks from 20% in the control arm to 50% in the experimental arm with P < .10. RESULTS: Of the 92 patients enrolled, 76 were randomized to the control arm (n = 40) or the experimental arm (n = 36). Of those, the median age was 62 years (range, 35-78 years), and 44 (58%) were men. The ORR at 12 weeks was 18% in the control arm vs 36% in the experimental arm (P = .07). Median progression-free survival was 1.9 months (95% CI, 1.7-6.9 months) vs 6.6 months (95% CI, 4.0-14.6 months) (hazard ratio, 0.71; 95% CI, 0.42-1.18; P = .19), and median overall survival was 7.6 months (95% CI, 6.0-13.9 months) vs 15.9 months (95% CI, 7.1 months to not reached) (hazard ratio, 0.66; 95% CI, 0.37-1.18; P = .16). Subgroup analyses showed the largest benefit from the addition of radiotherapy in patients with PD-L1-negative tumors. No increase in treatment-related toxic effects was observed in the experimental arm. CONCLUSIONS AND RELEVANCE: Stereotactic body radiotherapy prior to pembrolizumab was well tolerated. Although a doubling of ORR was observed, the results did not meet the study's prespecified end point criteria for meaningful clinical benefit. Positive results were largely influenced by the PD-L1-negative subgroup, which had significantly improved progression-free survival and overall survival. These results suggest that a larger trial is necessary to determine whether radiotherapy may activate noninflamed NSCLC toward a more inflamed tumor microenvironment. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02492568.

Results of a multicentre dosimetry audit using a respiratory phantom within the EORTC LungTech trial.

INTRODUCTION: The EORTC 22113-08113 LungTech trial assesses the safety and efficacy of SBRT for centrally located NSCLC. To insure protocol compliance an extensive RTQA procedure was implemented. METHODS: Twelve centres were audited using a CIRS008A phantom. The phantom was scanned using target inserts of 7.5 mm and 12.5 mm radius in static condition. For the 7.5 mm insert a 4DCT was acquired while moving according to a cos6 function. Treatment plans were measured using film and an ionization chamber. Wilcoxon's signed-rank tests were performed to compare the three plans across institutions. A Spearman correlation was calculated to evaluate the influence of factors such as PTV, slice thickness and total number of monitor units on the dosimetric results. RESULTS: The reference output dose median [min, max] variation was 0.5% [-1.1, +1.5]. The median deviations between chamber doses and point-planned doses were 1.8% [-0.1; 6.7] for the 7.5 mm and 1.1% [-2.8; 5.0] for the 12.5 mm sphere in static situation and 3.2% [-3.2; 15.7] for the dynamic situation. Film gamma median pass rates were 92.0% [68.0, 99.0] for 7.5 mm static, 96.2% [73.0, 99.0] for 12.5 mm static and 71.0% [40.0, 99.0] for 7.5 mm dynamic. Wilcoxon's signed-rank tests showed that the dynamic irradiations resulted in significantly lower gamma pass rates compared to the 12.5 mm static plan (p = 0.001). The total number of MUs per plan was correlated to both film and IC results. CONCLUSION: An end-to-end audit was successfully performed, revealing important variations between institutions especially in dynamic irradiations. This shows the importance of dosimetry audits and the potentials for further technique and methodology improvements.

Modeling radiation pneumonitis of pulmonary stereotactic body radiotherapy: The impact of a local dose-effect relationship for lung perfusion loss.

PURPOSE: To investigate if a local dose-effect (LDE) relationship for perfusion loss improves the NTCP model fit for SBRT induced radiation pneumonitis (RP) compared to conventional LDEs. METHODS AND MATERIALS: Multi-institutional data of 1015 patients treated with SBRT were analyzed. Dose distributions were converted to NTD with α/ß = 3 Gy. The Lyman-Kutcher-Burman NTCP model was fitted to the incidence grade ≥2 RP by maximum likelihood estimation with mean lung dose (MLD), equivalent uniform doses (EUD) using three LDE functions (power-law (EUDpower), logistic with 2 free parameters (EUDlog-free) and logistic with fixed parameters describing local perfusion loss (EUDPerfusion)) and volume above a threshold dose (Vx). Models were compared with the Akaike weights (Aw) derived from the Akaike information criteria (AIC). RESULTS: The median time to grade ≥2 RP was 4.2 months and plateaued after 17 months at 5.4%. A strong dose-effect relationship for RP incidence was observed. The EUDPerfusion based NTCP model had the lowest AIC. The Aw were 0.53, 0.19, 0.11, 0.11, 0.05 for the EUDPerfusion, Vx, MLD, EUDlog-free and EUDpower LDEs respectively. CONCLUSION: A LDE for perfusion loss provided modest improvement in NTCP model fit for SBRT induced radiation pneumonitis.

Quality assurance of four-dimensional computed tomography in a multicentre trial of stereotactic body radiotherapy of centrally located lung tumours.

BACKGROUND AND PURPOSE: Extensive radiation therapy quality assurance (RTQA) programs are needed when advanced radiotherapy treatments are used. As part of the RTQA four dimensional computed tomography (4DCT) imaging performance needs to be assessed. Here we present the RTQA data related to 4DCT procedures used within the context of stereotactic body radiotherapy (SBRT) of centrally located lung tumours. It provides an overview of the 4DCT acquisition methods and achievable accuracy of imaging lung tumour volumes. MATERIALS AND METHODS: 3DCT and 4DCT images were acquired from a CIRS phantom with spheres of 7.5 and 12.5 mm radius using the institutional scan protocols. Regular asymmetric tumour motion was simulated with varying amplitudes and periods. Target volumes were reconstructed using auto-contouring with scanner specific thresholds. Volume and amplitudes deviations were assessed. RESULTS: Although acquisition parameters were rather homogeneous over the eleven institutions analysed, volume deviations were observed. Average volume deviations for the 12.5 mm sphere were 15% (-4% to 69%) at end of inspiration, 2% (-2% to 9.0%) at end of expiration and 12% (0% to 36%) at mid-ventilation. For the 7.5 mm sphere deviations were 13% (-99% to 65%), 16% (-34% to 66%) and 1% (-13% to 20%), respectively. The amplitude deviation was generally within 2 mm although underestimations up to 6 mm were observed. CONCLUSIONS: The expiration phase was the most accurate phase to define the tumour volume and should be preferred for GTV delineation of tumours exhibiting large motion causing motion artefacts when using mid-ventilation or tracking techniques. The large variation found among the institutions indicated that further improvements in 4DCT imaging were possible. Recommendations for 4DCT QA have been formulated.

Improved pharmacodynamic (PD) assessment of low dose PARP inhibitor PD activity for radiotherapy and chemotherapy combination trials.

BACKGROUND: PARP inhibitors are currently evaluated in combination with radiotherapy and/or chemotherapy. As sensitizers, PARP inhibitors are active at very low concentrations therefore requiring highly sensitive pharmacodynamic (PD) assays. Current clinical PD-assays partly fail to provide such sensitivities. The aim of our study was to enable sensitive PD evaluation of PARP inhibitors for clinical sensitizer development. MATERIAL AND METHODS: PBMCs of healthy individuals and of olaparib and radiotherapy treated lung cancer patients were collected for ELISA-based PD-assays. RESULTS: PAR-signal amplification by ex vivo irradiation enabled an extended quantification range for PARP inhibitory activities after ex vivo treatment with inhibitors. This "radiation-enhanced-PAR" (REP) assay provided accurate IC50 values thereby also revealing differences among healthy individuals. Implemented in clinical radiotherapy combination Phase I trials, the REP-assay showed sensitive detection of PARP inhibition in patients treated with olaparib and establishes strong PARP inhibitory activities at low daily doses. CONCLUSIONS: Combination trials of radiotherapy and novel targeted agent(s) often require different and more sensitive PD assessments than in the monotherapy setting. This study shows the benefit and relevance of sensitive and adapted PD-assays for such combination purposes and provides proof of clinically relevant cellular PARP inhibitory activities at low daily olaparib doses.

Dose to heart substructures is associated with non-cancer death after SBRT in stage I-II NSCLC patients.

BACKGROUND AND PURPOSE: To investigate potential associations between dose to heart (sub)structures and non-cancer death, in early stage non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiation therapy (SBRT). METHODS: 803 patients with early stage NSCLC received SBRT with predominant schedules of 3×18Gy (59%) or 4×12Gy (19%). All patients were registered to an average anatomy, their planned dose deformed accordingly, and dosimetric parameters for heart substructures were obtained. Multivariate Cox regression and a sensitivity analysis were used to identify doses to heart substructures or heart region with a significant association with non-cancer death respectively. RESULTS: Median follow-up was 34.8months. Two year Kaplan-Meier overall survival rate was 67%. Of the deceased patients, 26.8% died of cancer. Multivariate analysis showed that the maximum dose on the left atrium (median 6.5Gy EQD2, range=0.009-197, HR=1.005, p-value=0.035), and the dose to 90% of the superior vena cava (median 0.59Gy EQD2, range=0.003-70, HR=1.025, p-value=0.008) were significantly associated with non-cancer death. Sensitivity analysis identified the upper region of the heart (atria+vessels) to be significantly associated with non-cancer death. CONCLUSIONS: Doses to mainly the upper region of the heart were significantly associated with non-cancer death. Consequently, dose sparing in particular of the upper region of the heart could potentially improve outcome, and should be further studied.