Redefining FLASH RT: the impact of mean dose rate and dose per pulse in the gastrointestinal tract

Background

The understanding of how varying radiation beam parameter settings affect the induction and magnitude of the FLASH effect remains limited.

Purpose

We sought to evaluate how the magnitude of radiation-induced gastrointestinal (GI) toxicity (RIGIT) depends on the interplay between mean dose rate (MDR) and dose per pulse (DPP).

Methods

C57BL/6J mice were subjected to total abdominal irradiation (11-14 Gy single fraction) under conventional irradiation (low DPP and low MDR, CONV) and various combinations of DPP and MDR up to ultra-high-dose-rate (UHDR) beam conditions. The effects of DPP were evaluated for DPPs of 1-6 Gy while the total dose and MDR were kept constant; the effects of MDR were evaluated for the range 0.3- 1440 Gy/s while the total dose and DPP were kept constant. RIGIT was quantified in non-tumor-bearing mice through the regenerating crypt assay and survival assessment. Tumor response was evaluated through tumor growth delay.

Results

Within each tested total dose using a constant MDR (>100 Gy/s), increasing DPP led to better sparing of regenerating crypts, with a more prominent effect seen at 12 and 14 Gy TAI. However, at fixed DPPs >4 Gy, similar sparing of crypts was demonstrated irrespective of MDR (from 0.3 to 1440 Gy/s). At a fixed high DPP of 4.7 Gy, survival was equivalently improved relative to CONV for all MDRs from 0.3 Gy/s to 104 Gy/s, but at a lower DPP of 0.93 Gy, increasing MDR produced a greater survival effect. We also confirmed that high DPP, regardless of MDR, produced the same magnitude of tumor growth delay relative to CONV using a clinically relevant melanoma mouse model.

Conclusions

This study demonstrates the strong influence that the beam parameter settings have on the magnitude of the FLASH effect. Both high DPP and UHDR appeared independently sufficient to produce FLASH sparing of GI toxicity, while isoeffective tumor response was maintained across all conditions.

Survival outcomes and toxicity of adjuvant immunotherapy after definitive concurrent chemotherapy with proton beam radiation therapy for patients with inoperable locally advanced non-small cell lung carcinoma

INTRODUCTION

Adjuvant immunotherapy (IO) following concurrent chemotherapy and photon radiation therapy confers an overall survival (OS) benefit for patients with inoperable locally advanced non-small cell lung carcinoma (LA-NSCLC); however, outcomes of adjuvant IO after concurrent chemotherapy with proton beam therapy (CPBT) are unknown. We investigated OS and toxicity after CPBT with adjuvant IO versus CPBT alone for inoperable LA-NSCLC.

MATERIALS AND METHODS

We analyzed 354 patients with LA-NSCLC who were prospectively treated with CPBT with or without adjuvant IO from 2009 to 2021. Optimal variable ratio propensity score matching (PSM) matched CPBT with CPBT + IO patients. Survival was estimated with the Kaplan-Meier method and compared with log-rank tests. Multivariable Cox proportional hazards regression evaluated the effect of IO on disease outcomes.

RESULTS

Median age was 70 years; 71 (20%) received CPBT + IO and 283 (80%) received CPBT only. After PSM, 71 CPBT patients were matched with 71 CPBT + IO patients. Three-year survival rates for CPBT + IO vs CPBT were: OS 67% vs 30% (P < 0.001) and PFS 59% vs 35% (P = 0.017). Three-year LRFS (P = 0.137) and DMFS (P = 0.086) did not differ. Receipt of adjuvant IO was a strong predictor of OS (HR 0.40, P = 0.001) and PFS (HR 0.56, P = 0.030), but not LRFS (HR 0.61, P = 0.121) or DMFS (HR 0.61, P = 0.136). There was an increased incidence of grade ≥3 esophagitis in the CPBT-only group (6% CPBT + IO vs 17% CPBT, P = 0.037).

CONCLUSION

This study, one of the first to investigate CPBT followed by IO for inoperable LA-NSCLC, showed that IO conferred survival benefits with no increased rates of toxicity.

BTN1A1 is a novel immune checkpoint mutually exclusive to PD-L1

BACKGROUND

While Programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) blockade is a potent antitumor treatment strategy, it is effective in only limited subsets of patients with cancer, emphasizing the need for the identification of additional immune checkpoints. Butyrophilin 1A1 (BTN1A1) has been reported to exhibit potential immunoregulatory activity, but its ability to function as an immune checkpoint remains to be systematically assessed, and the mechanisms underlying such activity have yet to be characterized.

METHODS

BTN1A1 expression was evaluated in primary tumor tissue samples, and its ability to suppress T-cell activation and T cell-dependent tumor clearance was examined. The relationship between BTN1A1 and PD-L1 expression was further characterized, followed by the development of a BTN1A1-specific antibody that was administered to tumor-bearing mice to test the amenability of this target to immune checkpoint inhibition.

RESULTS

BTN1A1 was confirmed to suppress T-cell activation in vitro and in vivo. Robust BTN1A1 expression was detected in a range of solid tumor tissue samples, and BTN1A1 expression was mutually exclusive with that of PD-L1 as a consequence of its inhibition of Janus-activated kinase/signal transducer and activator of transcription signaling-induced PD-L1 upregulation. Antibody-mediated BTN1A1 blockade suppressed tumor growth and enhanced immune cell infiltration in syngeneic tumor-bearing mice.

CONCLUSION

Together, these results confirm that the potential of BTN1A1 is a bona fide immune checkpoint and a viable immunotherapeutic target for the treatment of individuals with anti-PD-1/PD-L1 refractory or resistant disease, opening new avenues to improving survival outcomes for patients with a range of cancers.

Esophageal Cancer Outcomes After Definitive Chemotherapy With Intensity Modulated Proton Therapy

Purpose

The effectiveness of intensity-modulated proton therapy (IMPT) for esophageal cancer treated with definitive concurrent chemoradiation therapy remains inadequately explored. We investigated long-term outcomes and toxicity experienced by patients who received IMPT as part of definitive esophageal cancer treatment.

Patients and Methods

We retrospectively identified and analyzed 34 patients with locally advanced esophageal cancer who received IMPT with concurrent chemotherapy as a definitive treatment regimen at The University of Texas MD Anderson Cancer Center from 2011 to 2021. The median IMPT dose was 50.4 GyRBE in 28 fractions; concurrent chemotherapy consisted of fluorouracil and/or taxane and/or platinum. Survival outcomes were determined by the Kaplan-Meier method, and toxicity was scored according to the Common Terminology Criteria for Adverse Events version 4.0.

Results

The median age of all patients was 71.5 years. Most patients had stage III (cT3 cM0) adenocarcinoma of the lower esophagus. At a median follow-up time of 39 months, the 5-year overall survival rate was 41.1%; progression-free survival, 34.6%; local regional recurrence-free survival, 78.1%; and distant metastasis-free survival, 65.0%. Common acute chemoradiation therapy-related toxicities included hematologic toxicity, esophagitis (and late-onset), fatigue, weight loss, and nausea (and late-onset); grade 3 toxicity rates were 26.0% for hematologic, 18.0% for esophagitis and 9.0% for nausea. No patient had grade ≥3 wt loss or radiation pneumonitis, and no patients had pulmonary fibrosis or esophageal fistula. No grade ≥4 events were observed except for hematologic toxicity (lymphopenia) in 2 patients.

Conclusion

Long-term survival and toxicity were excellent after IMPT for locally advanced esophageal cancer treated definitively with concurrent chemoradiation therapy. When available, IMPT should be offered to such patients to minimize treatment-related cardiopulmonary toxicity without sacrificing outcomes.

Comparing 90-Day Postoperative Mortality After Neoadjuvant Proton-Based Versus Photon-Based Chemoradiotherapy for Esophageal Cancer

Purpose

Evidence suggests that proton-beam therapy (PBT) results in less toxicity and postoperative complications compared to photon-based radiotherapy in patients who receive chemoradiotherapy followed by esophagectomy for cancer. Ninety-day mortality (90DM) is an important measure of the postoperative (nononcologic) outcome as proxy of quality-of-care. We hypothesize that PBT could reduce 90DM compared to photon-based radiotherapy.

Materials and Methods

From a single-center retrospective database patients treated with chemoradiotherapy before esophagectomy for cancer were selected (1998-2022). Univariable logistic regression was used to study the association of radiotherapy modality with 90DM. Three separate methods were applied to adjust for confounding bias, including multivariable logistic regression, propensity score matching, and inverse probability of treatment weighting. Stratified analysis for the age threshold that maximized the difference in 90DM (ie, ≥67 vs <67 years) was performed.

Results

A total of 894 eligible patients were included and 90DM was 5/202 (2.5%) in the PBT versus 29/692 (4.2%) in the photon-based radiotherapy group (P = .262). After adjustment for age and tumor location, PBT versus photon-based radiotherapy was not significantly associated with 90DM (P = .491). The 90DM was not significantly different for PBT versus photon-based radiotherapy in the propensity score matching (P = .379) and inverse probability of treatment weighting cohort (P = .426). The stratified analysis revealed that in patients aged ≥67 years, PBT was associated with decreased 90DM (1.3% vs 8.8%; P = .026). Higher age significantly increased 90DM risk within the photon-based radiotherapy (8.8% vs 2.7%; P = .001), but not within the PBT group (1.3% vs 3.2%; P = .651).

Conclusion

No statistically significant difference was observed in postoperative 90DM after esophagectomy for cancer between PBT and photon-based neoadjuvant chemoradiotherapy. However, among older patients a signal was observed that PBT may reduce 90DM risk.

Severe Lymphopenia During Chemoradiation Therapy for Esophageal Cancer: Comprehensive Analysis of Randomized Phase 2B Trial of Proton Beam Therapy Versus Intensity Modulated Radiation Therapy

PURPOSE

Lymphocytes play an important role in antitumor immunity; however, they are also especially vulnerable to depletion during chemoradiation therapy (CRT). The purpose of this study was to compare the incidence of grade 4 lymphopenia (G4L) between proton beam therapy (PBT) and intensity modulated photon radiation therapy (IMRT) in patients with esophageal cancer treated with CRT in a completed randomized trial and to ascertain patient heterogeneity to G4L risk based on treatment and established prognostic factors.

METHODS AND MATERIALS

Between April 2012 and March 2019, a single-institution, open-label, nonblinded, phase 2 randomized trial (NCT01512589) was conducted at the University of Texas MD Anderson Cancer Center. Patients were randomly assigned to IMRT or PBT, either definitively or preoperatively. This secondary analysis of the randomized trial was G4L during concurrent CRT according to Common Terminology Criteria for Adverse Events version 5.0.

RESULTS

Among 105 patients evaluable for analysis, 44 patients (42%) experienced G4L at a median of 28 days after the start date of concurrent CRT. Induction chemotherapy (P = .003), baseline absolute lymphocyte count (P < .001), radiation therapy modality (P = .002), and planning treatment volume (P = .033) were found to be significantly associated with G4L. Multivariate classification analysis partitioned patients into 5 subgroups for whom the incidence of G4L was observed in 0%, 14%, 35%, 70%, and 100% of patients. The benefit of PBT over IMRT was most pronounced in patients with an intermediate baseline absolute lymphocyte count and large planning treatment volume (P = .011).

CONCLUSIONS

This is the first prospective evidence that limiting dose scatter by PBT significantly reduced the incidence of G4L, especially in the intermediate-risk patients. The implication of this immune-sparing effect of PBT, especially in the context of standard adjuvant immunotherapy, needs further examination in the current phase 3 randomized trials.

Consolidation Osimertinib Versus Durvalumab Versus Observation After Concurrent Chemoradiation in Unresectable EGFR-Mutant NSCLC: A Multicenter Retrospective Cohort Study

INTRODUCTION

Durvalumab improves survival when used as consolidation therapy after chemoradiation (CRT) in patients with stage III NSCLC. The optimal consolidation therapy for patients with EGFR-mutant (EGFRmut) stage III NSCLC remains unknown.

METHODS

In this multi-institutional, international retrospective analysis across 24 institutions, we evaluated outcomes in patients with stage III EGFRmut NSCLC treated with concurrent CRT followed by consolidation therapy with osimertinib, durvalumab, or observation between 2015 and 2022. Kaplan-Meier method was used to estimate real-world progression-free survival (rwPFS, primary end point) and overall survival (secondary end point). Treatment-related adverse events (trAEs) during consolidation treatment were defined using Common Terminology Criteria for Adverse Events version 5.0. Multivariable Cox regression analysis was used.

RESULTS

Of 136 patients with stage III EGFRmut NSCLC treated with definitive concurrent CRT, 56 received consolidation durvalumab, 33 received consolidation osimertinib, and 47 was on observation alone. Baseline characteristics were similar across the three cohorts. With a median follow-up of 46 months for the entire cohort, the median duration of treatment was not reached (NR) for osimertinib (interquartile range: NR-NR) and was 5.5 (interquartile range: 2.4-10.8) months with durvalumab. After adjusting for nodal status, stage III A/B/C, and age, patients treated with consolidation osimertinib had significantly longer 24-month rwPFS compared to those treated with durvalumab or in the observation cohorts (osimertinib: 86%, durvalumab: 30%, observation: 27%, p < 0.001 for both comparisons). There was no difference in rwPFS between the durvalumab and the observation cohorts. No significant difference in overall survival across the three cohorts was detected, likely due to the limited follow-up. Any-grade trAE occurred in 52% (2 [6.1%] grade ≥3) and 48% (10 [18%] grade ≥3) of patients treated with osimertinib and durvalumab, respectively. Of 45 patients who progressed on consolidation durvalumab, 37 (82%) subsequently received EGFR tyrosine kinase inhibitors. Of these, 14 (38%) patients developed trAEs including five patients with pneumonitis (14%; 2 [5.4%] grade ≥3) and five patients with diarrhea (14%; 1 [2.7%] grade ≥3).

CONCLUSIONS

This study suggests that among patients with stage III unresectable NSCLC with a sensitizing EGFR mutation, consolidation osimertinib was associated with a significantly longer rwPFS compared to durvalumab or observation. No unanticipated safety signals were observed with consolidation osimertinib.

Metformin in Conjunction With Stereotactic Radiotherapy for Early-stage Non-small Cell Lung Cancer: Long-term Results of a Prospective Phase II Clinical Trial

BACKGROUND/AIM

Non-small cell lung cancer (NSCLC) is increasingly detected in early stages and there is interest in improving outcomes with stereotactic body radiotherapy (SBRT). As metformin affects NSCLC signaling pathways, it might alter the metabolism of NSCLC treated with SBRT. This study investigated the long-term outcomes of a phase II clinical trial evaluating metformin in conjunction with SBRT for early-stage NSCLC.

PATIENTS AND METHODS

The trial evaluated patients with American Joint Commission on Cancer (AJCC) 7th edition Stage I-II, cT1-T2N0M0 NSCLC who were randomized 6:1 to receive metformin versus placebo in conjunction with SBRT. The outcomes analyzed included local failure (LF), progression-free survival (PFS), overall survival (OS), and Common Terminology Criteria for Adverse Events (CTCAE) version 4 toxicities.

RESULTS

There were 14 patients randomized to the metformin arm and one to the placebo. Median follow-up was four years. In the metformin group, the median PFS was 4.65 years [95% confidence interval (CI)=0.31-5.93] and median survival was 4.97 years (95%CI=3.05-4.61). Five year PFS was 27.8% (95%CI=5.3-57.3%) and OS was 46.0% (95%CI=16.0-71.9%). The one patient randomized to placebo was alive and without progression at five years. There were no LFs in the primary SBRT treatment volumes and no CTCAE version 4 Grade ≥3 adverse events.

CONCLUSION

Outcomes of SBRT and metformin for early-stage NSCLC were similar to historic controls. These findings along with the results of the NRG-LU001 and OCOG randomized trials do not support the therapeutic use of metformin for NSCLC.

Declarations of Independence: How Embedded Multicollinearity Errors Affect Dosimetric and Other Complex Analyses in Radiation Oncology

The statistical technique of multiple regression, commonly referred to as "multivariable regression," is often used in clinical research to quantify the relationships between multiple predictor variables and a single outcome variable of interest. The foundational theory underpinning multivariable regression assumes that all predictor variables are independent of one another. In other words, the effect of each independent variable is measured by its contribution to the regression equation while all other variables remain unchanged. In the presence of correlations between two or more variables, however, it is impossible to change one variable without a consequent change in the variable(s) it is linked to. This condition, known as "multicollinearity," can introduce errors into multivariable regression models by affecting estimates of the regression coefficients that quantify the relationship between individual predictor variables and the outcome variable. Errors that arise due to violations of the multicollinearity assumption are of special interest to radiation oncology researchers. Because of high levels of correlation among variables derived from points along individual organ dose-volume histogram (DVH) curves, as well as strong intercorrelations among dose-volume parameters in neighboring organs, dosimetric analyses are particularly subject to multicollinearity errors. For example, dose-volume parameters for the heart are strongly correlated not only with other points along the heart DVH curve but are likely also correlated with dose-volume parameters in neighboring organs such as the lung. In this paper, we describe the problem of multicollinearity in accessible terms and discuss examples of violations of the multicollinearity assumption within the radiation oncology literature. Finally, we provide recommendations regarding best practices for identifying and managing multicollinearity in complex data sets.

Severe radiation-induced lymphopenia during concurrent chemoradiotherapy for stage III non-small cell lung cancer: external validation of two prediction models

Background

Severe radiation-induced lymphopenia (RIL) in patients undergoing chemoradiotherapy (CRT) for non-small cell lung cancer (NSCLC) is associated with decreased immunotherapy efficacy and survival. At The Christie and MD Anderson Cancer Center (MDACC), prediction models for lymphopenia were developed in lung and esophageal cancer patients, respectively. The aim of this study was to externally validate both models in patients with stage III NSCLC.

Methods

Patients who underwent concurrent CRT for stage III NSCLC in 2019-2021 were studied. Outcomes were grade ≥3 and grade 4 lymphopenia during CRT. The Christie model predictors for grade ≥3 lymphopenia included age, baseline lymphocyte count, radiotherapy duration, chemotherapy, mean heart and lung doses, and thoracic vertebrae V20Gy. MDACC predictors for grade 4 lymphopenia were age, baseline lymphocyte count, planning target volume (PTV), and BMI. The external performance of both models was assessed.

Results

Among 100 patients, 78 patients (78%) developed grade ≥3 lymphopenia, with grade 4 lymphopenia in 17 (17%). For predicting grade ≥3 lymphopenia, the Christie and MDACC models yielded c-statistics of 0.77 and 0.79, respectively. For predicting grade 4 lymphopenia, c-statistics were 0.69 and 0.80, respectively. Calibration for the Christie and MDACC models demonstrated moderate and good agreement, respectively.

Conclusion

The PTV-based MDACC prediction model for severe RIL demonstrated superior external performance in NSCLC patients compared to the dosimetry-based Christie model. As such, the MDACC model can aid in identifying patients at high risk for severe lymphopenia. However, to optimize radiotherapy planning, further improvement and external validation of dosimetry-based models is desired.

Pneumonitis After Concurrent Chemoradiation and Immune Checkpoint Inhibition in Patients with Locally Advanced Non-small Cell Lung Cancer

AIMS

Pneumonitis is a common and potentially deadly complication of combined chemoradiation and immune checkpoint inhibition (CRT-ICI) in patients with locally advanced non-small cell lung cancer (LA-NSCLC). In this study we sought to identify the risk factors for pneumonitis with CRT-ICI therapy in LA-NSCLC cases and determine its impact on survival.

MATERIALS AND METHODS

We conducted a retrospective chart review of 140 patients with LA-NSCLC who underwent curative-intent CRT-ICI with durvalumab between 2018 and 2021. Pneumonitis was diagnosed by a multidisciplinary team of clinical experts. We used multivariable cause-specific hazard models to identify risk factors associated with grade ≥2 pneumonitis. We constructed multivariable Cox proportional hazard models to investigate the impact of pneumonitis on all-cause mortality.

RESULTS

The median age of the cohort was 67 years; most patients were current or former smokers (86%). The cumulative incidence of grade ≥2 pneumonitis was 23%. Among survivors, 25/28 patients had persistent parenchymal scarring. In multivariable analyses, the mean lung dose (hazard ratio 1.14 per Gy, 95% confidence interval 1.03-1.25) and interstitial lung disease (hazard ratio 3.8, 95% confidence interval 1.3-11.0) increased the risk for pneumonitis. In adjusted models, grade ≥2 pneumonitis (hazard ratio 2.5, 95% confidence interval 1.0-6.2, P = 0.049) and high-grade (≥3) pneumonitis (hazard ratio 8.3, 95% confidence interval 3.0-23.0, P < 0.001) were associated with higher all-cause mortality.

CONCLUSIONS

Risk factors for pneumonitis in LA-NSCLC patients undergoing CRT-ICI include the mean radiation dose to the lung and pre-treatment interstitial lung disease. Although most cases are not fatal, pneumonitis in this setting is associated with markedly increased mortality.

Feasibility and Clinical Implementation of Electron FLASH Radiation Therapy in the Yorkshire Swine Model

PURPOSE/OBJECTIVE(S)

Preclinical studies have shown FLASH radiation therapy (RT) increases the therapeutic index through reduction in normal tissue toxicity but with retained tumor control compared to conventional dose rate (CONV) RT. Dosimetry in FLASH beams is challenging and complex as beam monitoring and proper dosimetry analysis remain uncertain and under investigation. Despite these limitations, clinical translation of FLASH RT has already begun. For translation of FLASH RT from the preclinical stage, it is critical that robust clinical workflows and dosimetry methods be confidently established to ensure patient safety. Here, we present the clinical workflow for the Yorkshire pig, an animal that resembles the body dimension, weight, and biology of a human patient, with the goal to establish standard operating procedures to ensure a safe and robust clinical translation in our upcoming phase I study in cutaneous tumors. The study determines feasibility and safety while finding incidence of dose-limiting toxicities and maximum tolerable dose for future Phase II trials.

MATERIALS/METHODS

All procedures were approved by the institutional animal care and use committee. 6 pigs (40-50 kg) were placed under general anesthesia and underwent CT imaging for radiation therapy simulation purposes. The skin was first shaven, and targets on the dorsolateral flanks were marked with tattoos and BBs for CT visualization. Vacloc immobilization was used to allow for reproducible setup on the treatment couch. A treatment planning model was established for treatment planning and dose evaluation purposes. CONV and FLASH single and fractionated dose regimens were prescribed to the 90% isodose line in a 9 MeV beam. Skin collimation and bolus minimized beam penumbra and increased skin dose. Treatment time and pulse repetition frequency were constant between all FLASH fields. Prescription levels were varied via dose per pulse. Calibration and verification of these settings were performed utilizing a multi-dosimeter method for verification in solid water. Output of the beam was verified on the day of the treatment using beam current transformers. This same multi-dosimeter method was used as in-vivo dosimetry on treatment day and compared to the dose verification ensure full dose was received.

RESULTS

Variation between the three dosimeter methods was found to be within 5% among all pigs within the study. The maximum percent difference between dose verification and dose delivery was 6%. Consideration must be taken in dosimeter readout error due to the surface of the pig skin. FLASH and CONV toxicity results are currently under evaluation and will be published upon completion of the study.

CONCLUSION

Establishing guidelines and protocols for electron FLASH clinical translation is important to instill confidence in patient safety with this new technique. This study has further optimized and developed dosimetry tools and setup to be used in future clinical trials.

Long-Term Outcomes and Toxicity in Esophageal Cancer Patients after Neoadjuvant or Definitive Concurrent Chemotherapy with Proton Beam Therapy

PURPOSE/OBJECTIVE(S)

Proton-beam therapy (PT) is increasingly utilized over three dimensional-conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) photon irradiation for the treatment of various malignancies due to better toxicity reduction. We investigated the long-term outcomes and toxicity in esophageal cancer (EC) patients treated with PT as part of their neoadjuvant concurrent chemoradiation followed by surgery (nCRT) or definitive concurrent chemoradiation (dCRT) treatment regimen.

MATERIALS/METHODS

All consecutively treated, American Joint Committee on Cancer 7th edition clinical stage I-IV EC patients from 2006 to 2022 were retrospectively analyzed. Standard RT dose for most patients was 50.4 Gy/28 fractions. nCRT patients had surgery within 4 months post-RT. Kaplan-Meier method was used to determine overall survival (OS), locoregional recurrence-free survival (LRRFS) and distant metastatic-free survival (DMFS). Acute and chronic RT-related toxicities were graded with Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

There were 510 EC PT patients: 204 (40%) had nCRT and 306 (60%) had dCRT. Most lesions were located in the lower esophagus, of adenocarcinoma histology and treated with passive scatter PT. Overall median follow-up was 72 months. Median, 3- and 5-year OS for all patients were 43 months, 54.1% and 44.9%, respectively. Median LRRFS and DMFS were not reached. Esophagitis was the most common grade ≥3 (G3+) toxicity (59 patients; 28.9%, including a G4 and a G5 toxicity), followed by nausea (29 patients; 14.2%) and esophageal stricture (26 patients, 12.7%). With nCRT, median, 3- and 5-year OS were 80 months, 64.7% and 56.1%, respectively, while the median LRRFS and DMFS were not reached again. Their most common G3+ toxicity was esophagitis in 14 patients (6.9%) followed by nausea (8 patients; 3.9%). An nCRT patient developed G4 RT pneumonitis. Pathological complete response (pCR) was observed in 58 patients (28.4%). Surgery-related pulmonary, cardiac and gastrointestinal complications were reported in 38 (18.6%), 40 (19.6%) and 43 (21.1%) patients, respectively. dCRT patients had a median follow-up of 65 months, and median, 3- and 5-year OS of 32 months, 46.7% and 37.0%, respectively. Although the median LRRFS was not reached, the median DMFS was 74 months. The most observed dCRT G3+ toxicity was esophagitis (45 patients, 22.1%: including both G4 and G5 patients) and then esophageal stricture (23 patients, 11.3%). A dCRT patient developed G4 fistula.

CONCLUSION

To our knowledge, this is the largest single-institutional study on EC long-term outcomes and toxicity using PT. Our cohort reveals good outcomes and mostly mild CRT-related toxicities. Trimodality nCRT with protons demonstrates excellent outcomes relative to the CROSS trial (49.4 months) with identical pCR rate (29% in CROSS) and similar toxicity profile. nCRT with protons should be studied rigorously in the current randomized phase III trial NRG GI006.

Comparing 90-Day Post-Operative Mortality after Neoadjuvant Proton-Based vs. Photon-Based Chemoradiotherapy for Esophageal Cancer

PURPOSE/OBJECTIVE(S)

Standard of treatment for locally advanced esophageal cancer consists of chemoradiotherapy (CRT) followed by surgery. Evidence suggests that proton beam therapy (PBT) results in lower toxicity and fewer post-operative complications compared to photon-based radiotherapy (RT). Mortality in the first 90 days after surgery is a rare event occurring in 2-8% of patients, with higher reported rates (of up to 17%) in older patients. This 90-day mortality (90DM) rate is an important measure of post-operative (non-oncologic) mortality as a proxy of quality of care. We hypothesize that PBT could reduce the incidence of 90DM compared to photon-based RT.

MATERIALS/METHODS

From a single-center retrospectively acquired database patients with esophageal cancer treated with neoadjuvant CRT and esophagectomy in 1998-2022 were selected. Univariable logistic regression analyses were used to study the associations of RT modality and other patient- and treatment-related characteristics with 90DM. Subsequently, 3 separate methods were applied to adjust for confounding bias. These included multivariable logistic regression, 1:1 nearest-neighbor propensity score matching (PSM), and inverse probability of treatment weighting (IPTW). Finally, stratified analyses for patient groups aged ≥67 vs. <67 years were performed.

RESULTS

A total of 894 eligible patients were included (PBT, n = 202; photon-based RT, n = 692). PBT patients had a significantly higher age, better performance score, and a higher number of comorbidities. The 90DM rate was 5 (2.5%) in the PBT group and 29 (4.2%) in the photon-based RT group (p = 0.262). Significant univariable predictors of 90DM included higher age and tumor location. After multivariable adjustment, PBT vs. photon therapy was not significantly associated with 90DM (OR 0.49, 95% CI 0.18-1.31). The 90DM rates in the PSM cohort (n = 181 vs. n = 181) were 2.8% for PBT and 3.3% for photon-based RT (p = 0.379). The 90DM rates in the IPTW cohort were 2.8% for PBT and 4.1% for photon-based RT (p = 0.427). In the full cohort, stratified analysis for age groups revealed that in patients aged ≥67 years, PBT was associated with a decreased risk of 90DM compared to photon-based RT (1.3% vs. 8.8%; p = 0.046), which was not the case in patients aged <67 years. In the PSM cohort, a comparable (but non-significant) difference was observed in favor of PBT in patients aged ≥67 years (i.e., 1.5% vs. 7.5%; p = 0.099). Within-group analyses in the original cohort demonstrated that a higher age significantly increased the risk of 90DM within the photon-based RT group (8.8% vs. 2.7% for age ≥67 vs. <67 years; p = 0.001), but not within the PBT group (1.3% vs. 3.2%; p = 0.398).

CONCLUSION

Post-operative 90DM after esophagectomy for cancer was not significantly different between PBT and photon-based neoadjuvant CRT. However, among older patients we observed a signal that PBT may reduce the risk of 90DM. Higher age increased the risk of 90DM in patients who underwent photon-based RT, but not in patients who underwent PBT.

Prospective Trial of Using Imaging to Predict Pathologic Response and Clinical Outcomes in Locally Advanced Esophageal Cancer

PURPOSE/OBJECTIVE(S)

Trimodality therapy with chemoradiation (CRT) followed by esophagectomy is the standard of care for locally advanced esophageal cancer. An unresolved question is whether pathologic complete response (pCR) can be assessed non-invasively for patients post-CRT. In this study, we assessed whether diffusion-weighted imaging (DWI) with MRI or PET can be used as predictors of pCR and other clinical outcomes after CRT.

MATERIALS/METHODS

Patients were enrolled on a single-arm institutional trial (PA13-0380) assessing the role of imaging in predicting outcomes in potentially resectable esophageal patients undergoing trimodality therapy. All patients received neoadjuvant CRT, and 29 patients had subsequent surgery. DWI MRI and PET scans were obtained at baseline, 2 weeks after the start of CRT (interim) and 4 to 6 weeks after completion of CRT (follow up). Apparent diffusion coefficients (ADCs) were calculated based on DWI images. Circulating tumor DNA was obtained for 27 patients post-radiation using CAPP-Seq. Mann-Whitney tests compared imaging changes associated with pCR. Discrimination of pCR by imaging changes was quantified by received operating characteristics. Youden's index was applied to select optimal thresholds. Kaplan-Meier analysis was performed to assess differences in overall survival (OS) and progression-free survival (PFS) by changes in DWI, PET, and ctDNA parameters.

RESULTS

Our cohort of 60 patients had a median follow up of 42.7 months, age of 65.4 yrs, and ECOG of 1 at completion of CRT. 90% were male, 58% had a history of smoking, and 85% were white. 83% had adenocarcinoma with the rest squamous cell carcinoma. Stages of the patients ranged from IIA to IIIB. All had moderately (47%) or poorly (53%) differentiated disease. All received 41.4-50.4 Gy in 1.8 Gy fractions with the majority receiving 50.4 Gy (95%). 29 patients underwent surgery after CRT of which 8 (27.6%) had pCR. Mean ΔADC from baseline to mid-treatment was most associated with pCR (AUC = 0.98, p<0.001) for patients undergoing surgery. Max ΔADC from baseline to first follow-up was most associated with OS (p = 0.002) and PFS (p<0.001) for the whole cohort. 27 patients had ctDNA analyzed after RT with the presence of ctDNA significantly associated with worse OS (HR = 0.12, p = 0.05) and PFS (HR = 0.10, p = 0.002). Combining ctDNA and max ΔADC generated a model that was more predictive of OS and PFS than either alone. We found that neither the PET parameters of TLG or SUV max at baseline or changes in these parameters from baseline to mid-treatment or first follow-up were as predictive as DWI.

CONCLUSION

We show that changes in DWI is associated with pCR, OS, and PFS in resectable esophageal cancer patients undergoing CRT. DWI was more predictive than PET and a model combining DWI and ctDNA was the most predictive of clinical outcomes. This study shows the significant promise of using DWI in potentially guiding treatment decisions in esophageal cancer patients and will require validation in a larger cohort.

Subacute Cutaneous Toxicity with Single-Fraction Electron FLASH RT in Yorkshire Swine

PURPOSE/OBJECTIVE(S)

Information regarding acute/subacute skin toxicity of electron FLASH radiation therapy (RT) is limited. We evaluated short-term safety of electron FLASH for human trials by investigating subacute toxicity compared to conventional dose-rate RT (CONV) in the Yorkshire pig, an animal model known to closely approximate human skin and routinely used for toxicity studies.

MATERIALS/METHODS

Two healthy 50 kg pigs underwent CT imaging for RT treatment planning with field visualization via BBs and tattoos on each dorsolateral flank. Each target received a single fraction of 20, 25 or 30 Gy with FLASH and CONV on opposing sides delivered using a dedicated mobile linear accelerator. FLASH dose rates ranged from 164-245 Gy/sec (12 pulses delivered over 0.122 sec) while the CONV dose rate was set at 0.18 Gy/sec. Doses were verified using thermo- and optically stimulated luminescent dosimeters, and Gafchromic films. We obtained baseline and weekly images up to 98 days post-RT (D98) for blinded toxicity grading by 3 expert radiation oncologists using the modified RTOG radiation dermatitis (RD) scale. We measured erythema and pigmentation indices on those timepoints using a handheld spectrophotometer. We also obtained punch biopsies of targets and non-irradiated controls on D10 and D30 for RNA sequencing and two 6-marker multiplex immunofluorescence analyses of inflammation, immune response, and fibrosis. FLASH and CONV data were compared using repeated measures ANOVA and transcriptomic analyses using DESeq2.

RESULTS

All RT targets developed peak median grade 4 (ulceration, hemorrhage, or necrosis) RD by D84 regardless of FLASH or CONV delivery. However, FLASH targets developed peak RD later than CONV targets after 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D63 vs D42). FLASH induced qualitatively lower mean pigmentation and erythema indices than CONV for all 3 doses. Similarly, peak mean pigmentation indices occurred later with FLASH vs CONV for 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D77 vs D63). However, peak mean erythema indices occurred on the same day for FLASH and CONV (D63 for 20 Gy and D42 for 25 and 30 Gy). Transcriptomic analyses revealed significantly upregulated signals for wound healing (including TGF-beta, cell adhesion and extracellular matrix receptor interaction) and leukocyte infiltration with 20 Gy CONV mostly by D10, while FLASH upregulated those pathways only after 25 or 30 Gy, or by D30, or never at all. Preliminary immunofluorescence data showed FLASH may induce less T cell infiltrate and TGF-beta-expressing macrophages than CONV.

CONCLUSION

Single-fraction electron FLASH resulted in delayed onsets of both subacute cutaneous toxicity and wound healing with leukocytic infiltration signaling than dose-matched CONV based on both subjective and objective metrics of skin injury. Our findings suggest further investigations of optimal dose of electron FLASH for safe clinical translation is warranted, and we have a dose-finding study currently underway.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

Stereotactic ablative radiotherapy with or without immunotherapy for early-stage or isolated lung parenchymal recurrent node-negative non-small-cell lung cancer: an open-label, randomised, phase 2 trial

BACKGROUND

Stereotactic ablative radiotherapy (SABR) is the standard treatment for medically inoperable early-stage non-small-cell lung cancer (NSCLC), but regional or distant relapses, or both, are common. Immunotherapy reduces recurrence and improves survival in people with stage III NSCLC after chemoradiotherapy, but its utility in stage I and II cases is unclear. We therefore conducted a randomised phase 2 trial of SABR alone compared with SABR with immunotherapy (I-SABR) for people with early-stage NSCLC.

METHODS

We did an open-label, randomised, phase 2 trial comparing SABR to I-SABR, conducted at three different hospitals in TX, USA. People aged 18 years or older with histologically proven treatment-naive stage IA-IB (tumour size ≤4 cm, N0M0), stage IIA (tumour size ≤5 cm, N0M0), or stage IIB (tumour size >5 cm and ≤7 cm, N0M0) as per the American Joint Committee on Cancer version 8 staging system or isolated parenchymal recurrences (tumour size ≤7 cm) NSCLC (TanyNanyM0 before definitive surgery or chemoradiotherapy) were included in this trial. Participants were randomly assigned (1:1; using the Pocock & Simon method) to receive SABR with or without four cycles of nivolumab (480 mg, once every 4 weeks, with the first dose on the same day as, or within 36 h after, the first SABR fraction). This trial was unmasked. The primary endpoint was 4-year event-free survival (local, regional, or distant recurrence; second primary lung cancer; or death). Analyses were both intention to treat (ITT) and per protocol. This trial is registered with ClinicalTrials.gov (NCT03110978) and is closed to enrolment.

FINDINGS

From June 30, 2017, to March 22, 2022, 156 participants were randomly assigned, and 141 participants received assigned therapy. At a median 33 months' follow-up, I-SABR significantly improved 4-year event-free survival from 53% (95% CI 42-67%) with SABR to 77% (66-91%; per-protocol population, hazard ratio [HR] 0·38; 95% CI 0·19-0·75; p=0·0056; ITT population, HR 0·42; 95% CI 0·22-0·80; p=0·0080). There were no grade 3 or higher adverse events associated with SABR. In the I-SABR group, ten participants (15%) had grade 3 immunologial adverse events related to nivolumab; none had grade 3 pneumonitis or grade 4 or higher toxicity.

INTERPRETATION

Compared with SABR alone, I-SABR significantly improved event-free survival at 4 years in people with early-stage treatment-naive or lung parenchymal recurrent node-negative NSCLC, with tolerable toxicity. I-SABR could be a treatment option in these participants, but further confirmation from a number of currently accruing phase 3 trials is required.

FUNDING

Bristol-Myers Squibb and MD Anderson Cancer Center Alliance, National Cancer Institute at the National Institutes of Health through Cancer Center Core Support Grant and Clinical and Translational Science Award to The University of Texas MD Anderson Cancer Center.

Endothelial activation and fibrotic changes are impeded by laminar flow-induced CHK1-SENP2 activity through mechanisms distinct from endothelial-to-mesenchymal cell transition

Background

The deSUMOylase sentrin-specific isopeptidase 2 (SENP2) plays a crucial role in atheroprotection. However, the phosphorylation of SENP2 at T368 under disturbed flow (D-flow) conditions hinders its nuclear function and promotes endothelial cell (EC) activation. SUMOylation has been implicated in D-flow-induced endothelial-to-mesenchymal transition (endoMT), but the precise role of SENP2 in counteracting this process remains unclear.

Method

We developed a phospho-specific SENP2 S344 antibody and generated knock-in (KI) mice with a phospho-site mutation of SENP2 S344A using CRISPR/Cas9 technology. We then investigated the effects of SENP2 S344 phosphorylation under two distinct flow patterns and during hypercholesteremia (HC)-mediated EC activation.

Result

Our findings demonstrate that laminar flow (L-flow) induces phosphorylation of SENP2 at S344 through the activation of checkpoint kinase 1 (CHK1), leading to the inhibition of ERK5 and p53 SUMOylation and subsequent suppression of EC activation. We observed a significant increase in lipid-laden lesions in both the aortic arch (under D-flow) and descending aorta (under L-flow) of female hypercholesterolemic SENP2 S344A KI mice. In male hypercholesterolemic SENP2 S344A KI mice, larger lipid-laden lesions were only observed in the aortic arch area, suggesting a weaker HC-mediated atherogenesis in male mice compared to females. Ionizing radiation (IR) reduced CHK1 expression and SENP2 S344 phosphorylation, attenuating the pro-atherosclerotic effects observed in female SENP2 S344A KI mice after bone marrow transplantation (BMT), particularly in L-flow areas. The phospho-site mutation SENP2 S344A upregulates processes associated with EC activation, including inflammation, migration, and proliferation. Additionally, fibrotic changes and up-regulated expression of EC marker genes were observed. Apoptosis was augmented in ECs derived from the lungs of SENP2 S344A KI mice, primarily through the inhibition of ERK5-mediated expression of DNA damage-induced apoptosis suppressor (DDIAS).

Summary

In this study, we have revealed a novel mechanism underlying the suppressive effects of L-flow on EC inflammation, migration, proliferation, apoptosis, and fibrotic changes through promoting CHK1-induced SENP2 S344 phosphorylation. The phospho-site mutation SENP2 S344A responds to L-flow through a distinct mechanism, which involves the upregulation of both mesenchymal and EC marker genes.

Predicting benefit from immune checkpoint inhibitors in patients with non-small-cell lung cancer by CT-based ensemble deep learning: a retrospective study

BACKGROUND

Only around 20-30% of patients with non-small-cell lung cancer (NCSLC) have durable benefit from immune-checkpoint inhibitors. Although tissue-based biomarkers (eg, PD-L1) are limited by suboptimal performance, tissue availability, and tumour heterogeneity, radiographic images might holistically capture the underlying cancer biology. We aimed to investigate the application of deep learning on chest CT scans to derive an imaging signature of response to immune checkpoint inhibitors and evaluate its added value in the clinical context.

METHODS

In this retrospective modelling study, 976 patients with metastatic, EGFR/ALK negative NSCLC treated with immune checkpoint inhibitors at MD Anderson and Stanford were enrolled from Jan 1, 2014, to Feb 29, 2020. We built and tested an ensemble deep learning model on pretreatment CTs (Deep-CT) to predict overall survival and progression-free survival after treatment with immune checkpoint inhibitors. We also evaluated the added predictive value of the Deep-CT model in the context of existing clinicopathological and radiological metrics.

FINDINGS

Our Deep-CT model demonstrated robust stratification of patient survival of the MD Anderson testing set, which was validated in the external Stanford set. The performance of the Deep-CT model remained significant on subgroup analyses stratified by PD-L1, histology, age, sex, and race. In univariate analysis, Deep-CT outperformed the conventional risk factors, including histology, smoking status, and PD-L1 expression, and remained an independent predictor after multivariate adjustment. Integrating the Deep-CT model with conventional risk factors demonstrated significantly improved prediction performance, with overall survival C-index increases from 0·70 (clinical model) to 0·75 (composite model) during testing. On the other hand, the deep learning risk scores correlated with some radiomics features, but radiomics alone could not reach the performance level of deep learning, indicating that the deep learning model effectively captured additional imaging patterns beyond known radiomics features.

INTERPRETATION

This proof-of-concept study shows that automated profiling of radiographic scans through deep learning can provide orthogonal information independent of existing clinicopathological biomarkers, bringing the goal of precision immunotherapy for patients with NSCLC closer.

FUNDING

National Institutes of Health, Mark Foundation Damon Runyon Foundation Physician Scientist Award, MD Anderson Strategic Initiative Development Program, MD Anderson Lung Moon Shot Program, Andrea Mugnaini, and Edward L C Smith.

An ERK5-NRF2 Axis Mediates Senescence-Associated Stemness and Atherosclerosis

BACKGROUND

ERK5 (extracellular signal-regulated kinase 5) is a dual kinase transcription factor containing an N-terminal kinase domain and a C-terminal transcriptional activation domain. Many ERK5 kinase inhibitors have been developed and tested to treat cancer and inflammatory diseases. However, recent data have raised questions about the role of the catalytic activity of ERK5 in proliferation and inflammation. We aimed to investigate how ERK5 reprograms myeloid cells to the proinflammatory senescent phenotype, subsequently leading to atherosclerosis.

METHODS

A ERK5 S496A (dephosphorylation mimic) knock in (KI) mouse model was generated using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9), and atherosclerosis was characterized by hypercholesterolemia induction. The plaque phenotyping in homozygous ERK5 S496A KI and wild type (WT) mice was studied using imaging mass cytometry. Bone marrow-derived macrophages were isolated from hypercholesterolemic mice and characterized using RNA sequencing and functional in vitro approaches, including senescence, mitochondria reactive oxygen species, and inflammation assays, as well as by metabolic extracellular flux analysis.

RESULTS

We show that atherosclerosis was inhibited in ERK5 S496A KI mice. Furthermore, ERK5 S496 phosphorylation mediates both senescence-associated secretory phenotype and senescence-associated stemness by upregulating AHR (aryl hydrocarbon receptor) in plaque and bone marrow-derived macrophages isolated from hypercholesterolemic mice. We also discovered that ERK5 S496 phosphorylation could induce NRF2 (NFE2-related factor 2) SUMOylation at a novel K518 site to inhibit NRF2 transcriptional activity without altering ERK5 catalytic activity and mediates oxidized LDL (low-density lipoprotein)-induced senescence-associated secretory phenotype. Specific ERK5 kinase inhibitors (AX15836 and XMD8-92) also inhibited ERK5 S496 phosphorylation, suggesting the involvement of ERK5 S496 phosphorylation in the anti-inflammatory effects of these ERK5 kinase inhibitors.

CONCLUSIONS

We discovered a novel mechanism by which the macrophage ERK5-NRF2 axis develops a unique senescence-associated secretory phenotype/stemness phenotype by upregulating AHR to engender atherogenesis. The finding of senescence-associated stemness phenotype provides a molecular explanation to resolve the paradox of senescence in proliferative plaque by permitting myeloid cells to escape the senescence-induced cell cycle arrest during atherosclerosis formation.

Possible molecular mechanisms underlying the development of atherosclerosis in cancer survivors

Cancer survivors undergone treatment face an increased risk of developing atherosclerotic cardiovascular disease (CVD), yet the underlying mechanisms remain elusive. Recent studies have revealed that chemotherapy can drive senescent cancer cells to acquire a proliferative phenotype known as senescence-associated stemness (SAS). These SAS cells exhibit enhanced growth and resistance to cancer treatment, thereby contributing to disease progression. Endothelial cell (EC) senescence has been implicated in atherosclerosis and cancer, including among cancer survivors. Treatment modalities for cancer can induce EC senescence, leading to the development of SAS phenotype and subsequent atherosclerosis in cancer survivors. Consequently, targeting senescent ECs displaying the SAS phenotype hold promise as a therapeutic approach for managing atherosclerotic CVD in this population. This review aims to provide a mechanistic understanding of SAS induction in ECs and its contribution to atherosclerosis among cancer survivors. We delve into the mechanisms underlying EC senescence in response to disturbed flow and ionizing radiation, which play pivotal role in atherosclerosis and cancer. Key pathways, including p90RSK/TERF2IP, TGFβR1/SMAD, and BH4 signaling are explored as potential targets for cancer treatment. By comprehending the similarities and distinctions between different types of senescence and the associated pathways, we can pave the way for targeted interventions aim at enhancing the cardiovascular health of this vulnerable population. The insights gained from this review may facilitate the development of novel therapeutic strategies for managing atherosclerotic CVD in cancer survivors.

The abscopal effect in patients with cancer receiving immunotherapy

Interest in the abscopal effect has been rekindled over the past decade with the advent of immunotherapy. Although purportedly elusive, this phenomenon is being increasingly reported. Venturing further using a multimodality approach with an array of systemic agents and unconventional modalities is direly needed. In this perspective, we describe the fundamentals of abscopal responses (ARs), explore combinations with systemic therapies that hold promise in eliciting ARs, and reconnoiter unconventional modalities that may induce ARs. Finally, we scrutinize prospective agents and modalities that exhibit preclinical ability to elicit ARs and discuss prognostic biomarkers, their limitations, and pathways of abscopal resistance for reproducibility.

Abstract 3310: Extracellular vesicles budding from stromal macrophages in the blood of metastatic non-small cell lung cancer patients correlates with poor survival

Purpose: Cancer extracellular vesicles (EVs) are involved in cellular communication, tumor growth, progression, and metastasis in cancer. The origins of EVs, their formation, and potential clinical use as biomarkers are not well understood. Recently, budding of extracellular structures on Cancer Associated Macrophage-Like Cells [CAMLs] a specific subtype of phagocytic circulating stromal cells has been observed in metastatic non-small cell lung carcinoma (mNSCLC) patients. In this prospective analysis of n=40 mNSCLC samples, we enumerated EV budding on CAMLs to determine if their formation had an effect on clinical outcomes. These preliminary results suggest that EV budding from a specific subtype of circulating tumor associated macrophage prognosticates for worse clinical outcome which may serve as the mechanism for cancer EV formation and spread throughout the body.

Patients and Methods: We initiated a single blind prospective pilot study to evaluate extracellular budding on the CAMLs of mNSCLC patients from blood samples obtained prior to therapy to determine their prevalence and clinical utility. Anonymized blood was procured and filtered to isolate CAMLs and stained for cytokeratin, CD45, CD31 and PD-L1. EV budding was observed as small (≤1 µm) bulbous protrusions from the cell periphery. EVs were quantified and compared against patient progression free survival (PFS) and overall survival (OS) with hazard ratios (HRs) at 24 months by censored univariate analysis. The imaged EVs were also characterized by their PD-L1 biomarker expression.

Results: CAMLs were identified in 88% (n=35/40) of all samples, with EV budding identified in 60% (n=21/35) of CAMLs. These EVs appeared with tumor positive proteins (i.e. CD31, CD45, PD-L1 and cytokeratin). With a minimum of 24 months of follow-up, it was determined that the presence of EV budding in patients’ CAMLs was associated with significantly worse PFS (HR=4.00, 95%CI=1.4-12, p=0.0251) and borderline significant OS (HR=3.57, 95%CI=1.1-12, p=0.0747).

Conclusions: EV budding found on phagocytic stromal cells found in the blood appear with tumor positive biomarkers and predict poor survival. These findings suggest that CAMLs are an origin cell for some cancer EVs. Larger validation studies and cross comparison of PD-L1 on EVs as it related to immunotherapy response is ongoing.

Citation Format: Jillian A. Moran, Steven H. Lin, Martin J. Edelman, Pablo Lopez, Jianzhong He, Yawei Qiao, Ting Xu, Zhongxing Liao, Kirby P. Gardner, Cha-Mei Tang, Daniel L. Adams. Extracellular vesicles budding from stromal macrophages in the blood of metastatic non-small cell lung cancer patients correlates with poor survival [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 3310.

Independent Reproduction of the FLASH Effect on the Gastrointestinal Tract: A Multi-Institutional Comparative Study

FLASH radiation therapy (RT) is a promising new paradigm in radiation oncology. However, a major question that remains is the robustness and reproducibility of the FLASH effect when different irradiators are used on animals or patients with different genetic backgrounds, diets, and microbiomes, all of which can influence the effects of radiation on normal tissues. To address questions of rigor and reproducibility across different centers, we analyzed independent data sets from The University of Texas MD Anderson Cancer Center and from Lausanne University (CHUV). Both centers investigated acute effects after total abdominal irradiation to C57BL/6 animals delivered by the FLASH Mobetron system. The two centers used similar beam parameters but otherwise conducted the studies independently. The FLASH-enabled animal survival and intestinal crypt regeneration after irradiation were comparable between the two centers. These findings, together with previously published data using a converted linear accelerator, show that a robust and reproducible FLASH effect can be induced as long as the same set of irradiation parameters are used.

Risk stratification of postoperative cardiopulmonary toxicity after trimodality therapy for esophageal cancer

Purpose/objective

Postoperative toxicity for esophageal cancer impacts patient quality of life and potentially overall survival (OS). We studied whether patient and toxicity parameters post-chemoradiation therapy predict for post-surgical cardiopulmonary total toxicity burden (CPTTB) and whether CPTTB was associated with short and long-term outcomes.

Materials/methods

Patients had biopsy-proven esophageal cancer treated with neoadjuvant chemoradiation and esophagectomy. CPTTB was derived from total perioperative toxicity burden (Lin et al. JCO 2020). To develop a CPTTB risk score predictive for major CPTTB, recursive partitioning analysis was used.

Results

From 3 institutions, 571 patients were included. Patients were treated with 3D (37%), IMRT (44%), and proton therapy (19%). 61 patients had major CPTTB (score ≥ 70). Increasing CPTTB was predictive of decreased OS (p<0.001), lengthier post-esophagectomy length of stay (LOS, p<0.001), and death or readmission within 60 days of surgery (DR60, p<0.001). Major CPTTB was also predictive of decreased OS (hazard ratio = 1.70, 95% confidence interval: 1.17-2.47, p=0.005). The RPA-based risk score included: age ≥ 65, grade ≥ 2 nausea or esophagitis attributed to chemoradiation, and grade ≥ 3 hematologic toxicity attributed to chemoradiation. Patients treated with 3D radiotherapy had inferior OS (p=0.010) and increased major CPTTB (18.5% vs. 6.1%, p<0.001).

Conclusion

CPTTB predicts for OS, LOS, and DR60. Patients with 3D radiotherapy or age ≥ 65 years and chemoradiation toxicity are at highest risk for major CPTTB, predicting for higher short and long-term morbidity and mortality. Strategies to optimize medical management and reduce toxicity from chemoradiation should be strongly considered.

Gene expression profiling of circulating tumor cells captured by MicroCavity Array is superior to enumeration in demonstrating therapy response in patients with newly diagnosed advanced and locally advanced non-small cell lung cancer

Background

Circulating tumor cells (CTCs) are a promising non-invasive tool for monitoring therapy response. The only Food and Drug Administration (FDA)-approved test is limited to enumeration of epithelial CTC without further characterization and is not approved for the management of non-small cell lung cancer (NSCLC). Here we use a MicroCavity Array (MCA) system to capture CTC agnostic of epithelial markers for further molecular testing in NSCLC.

Methods

CTCs were enumerated by fluorescent microscopy as longitudinal sampling throughout disease management from 213 NSCLC patients. CTC-enriched samples from a subset of 127 patients were interrogated for gene expression by reverse transcription polymerase chain reaction (RT-PCR) using a customized pre-selected panel of 20 genes.

Results

At least 1 CTC was detected by enumeration in 53.8% of samples. Most patients had fewer than 5 CTCs (91%) and the highest observed count was 35 CTCs. Enumeration of single CTCs was not prognostic, although detection of CTC clusters at any time point was associated with increased risk of progression [hazard ratio (HR) 3.00, 95% confidence interval (CI): 1.1-8.2, P=0.0318]. In contrast, 124 (97.6%) patients with samples interrogated for gene expression had at least 1 gene detectable in at least 1 sample, and 101 (79.5%) had at least one elevated epithelial gene in at least one timepoint. High expression of BCL2, CD274 [programmed death-ligand 1 (PD-L1)], CDH1, EPCAM, FGFR1, FN1, KRT18, MET and MUC1 were associated with poor prognosis. Patients with CTCs positive for at least 3 epithelial genes at baseline all progressed within 10 months (HR 8.2, P<0.001, 95% CI: 3.2-21.1). BCL2, CD274 (PD-L1), EPCAM and MUC1 remained significant independent prognostic factors in multivariate, time-dependent analyses of progression and death.

Conclusions

The selective profile of CTC genes and identification of CTC clusters better correlated with prognosis than enumeration of enriched CTC in NSCLC patients in this study.

Benchmarking Outcomes for Molecularly Characterized Synchronous Oligometastatic Non-Small-Cell Lung Cancer Reveals EGFR Mutations to Be Associated With Longer Overall Survival

PURPOSE

Local consolidative therapy (LCT) for patients with synchronous oligometastatic non-small-cell lung cancer is an evolving treatment strategy, but outcomes following LCT stratified by genetic mutations have not been reported. We sought to identify genomic associations with overall survival (OS) and progression-free survival (PFS) for these patients.

METHODS

We identified all patients presenting between 2000 and 2017 with stage IV non-small-cell lung cancer and ≤ 3 synchronous metastatic sites. Patients were grouped according to mutational statuses. Primary outcomes included OS and PFS following initial diagnosis.

RESULTS

Of 194 included patients, 121 received comprehensive LCT to all sites of disease with either surgery or radiation. TP53 mutations were identified in 40 of 78 (55%), KRAS in 32 of 95 (34%), EGFR in 24 of 109 (22%), and STK11 in nine of 77 (12%). At median follow-up of 96 months, median OS and PFS were 26 (95% CI, 23 to 31) months and 11 (95% CI, 9 to 13) months, respectively. On multivariable analysis, patients with EGFR mutations had lower mortality risk (hazard ratio [HR], 0.53; 95% CI, 0.29 to 0.98; P = .044) compared with wild-type patients, and patients with STK11 mutations had higher risk of progression or mortality (HR, 2.32; 95% CI, 1.12 to 4.79; P = .023) compared with wild-type patients. TP53 and KRAS mutations were not associated with OS or PFS. Among 71 patients with known EGFR mutational status who received comprehensive LCT, EGFR mutations were associated with lower mortality compared with wild-type (HR, 0.45; 95% CI, 0.22 to 0.94; P = .032).

CONCLUSION

When compared with wild-type patients, those with EGFR and STK11 mutations had longer OS and shorter PFS, respectively. EGFR mutations were associated with longer OS among oligometastatic patients treated with comprehensive LCT in addition to systemic therapy.

Monitoring PD-L1 Expression on Circulating Tumor-Associated Cells in Recurrent Metastatic Non-Small-Cell Lung Carcinoma Predicts Response to Immunotherapy With Radiation Therapy

PURPOSE

Current diagnostic methods to determine programmed death 1 (PD-1) receptor and its ligand (PD-L1)/PD-1 immunotherapy (immune checkpoint inhibitor [ICI]) efficacy in recurrent or metastatic non-small-cell lung carcinoma (rmNSCLC) are imprecise. Although previously shown that patients with high tumor PD-L1 (≥ 50%) demonstrate clinical benefit in the form of disease reduction and improved survival, patients with low PD-L1 (< 50%) sometimes benefit from treatment. Since the PD-L1/PD-1 pathway is dynamic, monitoring PD-L1 levels during treatment may be more accurate than a static baseline tumor biopsy; however, rebiopsying the primary or metastatic disease is rarely feasible. Liquid biopsies that measure the upregulation of PD-L1 on tumor-associated cells (TACs), ie, cancer-associated macrophage-like cells and circulating tumor cells, have been performed, but their predictive value for ICI therapy efficacy is unknown.

MATERIALS AND METHODS

We initiated a single-blind prospective study to evaluate TAC PD-L1 expression changes in rmNSCLC from blood samples before (T0) and after (T1) treatment with ICI (ICI, n = 41) or without ICI (no ICI, n = 41). Anonymized blood was filtered to isolate TACs, which were then quantified for high/low PD-L1 expression. Progression-free survival (PFS) or overall survival (OS) hazard ratios (HRs) were evaluated at 18 and 24 months by censored univariate analysis.

RESULTS

Increased TAC PD-L1 expression between T0 and T1 in patients who were not treated with ICI had no relationship with PFS or OS. However, increased TAC PD-L1 expression between T0 and T1 in patients treated with ICI had significantly better PFS (HR, 3.49; 95% CI, 1.5 to 8.3; P = .0091) and OS (HR, 3.058; 95% CI, 1.2 to 7.9; P = .0410).

CONCLUSION

Blood-based monitoring of dynamic changes in PD-L1 in TACs appears to identify patients with rmNSCLC who may benefit from ICI.

Final efficacy outcomes of atezolizumab with chemoradiation for unresectable NSCLC: The phase II DETERRED trial

INTRODUCTION

The phase II DETERRED trial assessed the safety and efficacy of consolidation and concurrent immunotherapy with chemoradiation in unresectable locally advanced non-small cell lung cancer. We present updated efficacy analysis of this trial.

METHODS

The trial was conducted in 2 parts with patients in part 1 (n = 10) receiving chemoradiation with consolidation atezolizumab, while patients in part 2 (n = 30) received concurrent and consolidation atezolizumab. Progression-free survival (PFS), time to second progression (PFS2), and overall survival (OS) were assessed using Kaplan-Meier analysis. Subset analyses were performed by programmed cell death ligand-1 (PD-L1) status and targetable driver oncogene mutation status.

RESULTS

At a median follow-up of 39.2 months, the median PFS for part 1 was 18.9 months and 15.1 months for part 2. Median OS for part 1 was 26.5 months and was not reached for part 2. For the cohort, 3-year OS was 53.8%, while 4-year OS was 47.4%. Patients with targetable driver oncogene mutations had a median PFS of 9.4 months and OS of not reached compared to 16.6 months (HR: 3.49, p = 0.02) and 26.9 months (HR: 0.40, p = 0.12) respectively compared to those without targetable driver oncogene mutations. Patients with PD-L1 < 1% had median PFS of 11.0 months and OS of 26.5 months compared to 27.4 months (HR: 2.01, p = 0.10) and not reached (HR: 1.49, p = 0.41) respectively for those with PD-L1 ≥ 1%.

CONCLUSIONS

In the DETERRED trial, chemoradiation with concurrent and/or consolidative atezolizumab led to comparable efficacy as consolidative durvalumab in the PACIFIC trial. The presence of targetable driver oncogene mutations led to worse PFS, while PD-L1 < 1% trended to worse PFS.

On target methods to induce abscopal phenomenon for Off‐Target effects: From happenstance to happenings

Although the "abscopal phenomenon" has been described several decades ago, this phenomenon lately has been obtaining momentous traction with the dawn of immune-based therapies. There has been increased cross talk among radiation oncologists, oncologists and immunologists and consequently a surge in the number of prospective clinical trials. This must be coupled with translation work from these clinical trials to aid in eventual identification of patients who may benefit. Abscopal effects may be induced by local and systemic methods, conventional radiotherapy, particle radiation, radionucleotide methods, cryoablation and brachytherapy. These approaches have all been reported to be stimulate abscopal effect. Immune induction by immune checkpoint therapy, immune adjuvants, cellular therapy including CAR and NK cell therapies may generate systemic abscopal response. With increasing recognition of this effect, there remains a lot of work to explore the modalities of inducing abscopal responses and ultimate prediction or prognostication on stratifying who may benefit. Ultimately, there is an urgent need for prospective studies and data to tease apart which one of these modalities can be applied to the appropriate candidate, to the appropriate cancer at the appropriate setting. This review seeks to elucidate readers on the different modalities of radiation, systemic therapies and other techniques rarely explored to potentiate the abscopal effect from a mere coincidence to a finite occurrence.

Radiation therapy induces immunosenescence mediated by p90RSK

Radiation therapy (RT) to the chest increases the patients' risk of cardiovascular disease (CVD). A complete understanding of the mechanisms by which RT induces CVD could lead to specific preventive, therapeutic approaches. It is becoming evident that both genotoxic chemotherapy agents and radiation induce mitochondrial dysfunction and cellular senescence. Notably, one of the common phenotypes observed in cancer survivors is accelerated senescence, and immunosenescence is closely related to both cancer risk and CVD development. Therefore, suppression of immunosenescence can be an ideal target to prevent cancer treatment-induced CVD. However, the mechanism(s) by which cancer treatments induce immunosenescence are incompletely characterized. We isolated peripheral blood mononuclear cells (PBMCs) before and 3 months after RT from 16 thoracic cancer patients. We characterized human immune cell lineages and markers of senescence, DNA damage response (DDR), efferocytosis, and determinants of clonal hematopoiesis of indeterminant potential (CHIP), using mass cytometry (CyTOF). We found that the frequency of the B cell subtype was decreased after RT. Unsupervised clustering of the CyTOF data identified 138 functional subsets of PBMCs. Compared with baseline, RT increased TBX21 (T-bet) expression in the largest B cell subset of Ki67-/DNMT3a+naïve B cells, and T-bet expression was correlated with phosphorylation of p90RSK expression. CD38 expression was also increased in naïve B cells (CD27-) and CD8+ effector memory CD45RA T cells (TEMRA). In vitro, we found the critical role of p90RSK activation in upregulating (1) CD38+/T-bet+ memory and naïve B, and myeloid cells, (2) senescence-associated β-gal staining, and (3) mitochondrial reactive oxygen species (ROS) after ionizing radiation (IR). These data suggest the crucial role of p90RSK activation in immunosenescence. The critical role of p90RSK activation in immune cells and T-bet induction in upregulating atherosclerosis formation has been reported. Furthermore, T-bet directly binds to the CD38 promoter region and upregulates CD38 expression. Since both T-bet and CD38 play a significant role in the process of immunosenescence, our data provide a cellular and molecular mechanism that links RT-induced p90RSK activation and the immunosenescence with T-bet and CD38 induction observed in thoracic cancer patients treated by RT and suggests that targeting the p90RSK/T-bet/CD38 pathway could play a role in preventing the radiation-associated CVD and improving cancer prognosis by inhibiting immunosenescence.

Treatment-related pulmonary adverse events induced by chemoradiation and Durvalumab affect survival in locally advanced non-small cell lung cancer

PURPOSE

We compared treatment-related pulmonary adverse events (TRPAE), progression-free survival (PFS), and overall survival (OS) among locally advanced non-small cell lung cancer (NSCLC) patients who received concurrent chemoradiotherapy (CRT) versus CRT followed by immune check point inhibitor (ICI) immunotherapy (CRTI).

MATERIALS AND METHODS

TRPAE was defined as any pulmonary events as defined in CTCAE v.5 occurring within 12 months after completion of radiotherapy. Outcomes were compared between CRT and CTRI by Cox proportional hazard regression and Kaplan-Meier analyses. We also assessed if TRPAE-induced discontinuation of ICI affected survival.

RESULTS

We analyzed 326 patients treated between July 2010 and November 2019; 195 patients received CRT and 131 received CRTI. The incidences of severe grade ≥ 3 TRPAE were similar between the two groups, however, symptomatic TRPAE was almost doubled in CRTI group (65.7 % CTRI vs 35.9 % CRT, P < 0.0001). The rates of 4-year OS and PFS were 54.5 % vs 36.7 % (P = 0.0003) and 43.8 % vs 35.8 % (P = 0.038) in CRT + Durvalumab and CRT group, respectively. Receipt of ICI Durvalumab was associated with better 4-year OS (HR 0.53, 95 % CI 0.36-0.78, P = 0.001) and PFS (HR 0.55, 95 % CI 0.38-0.80, P = 0.002). Patients who discontinued ICI because of TRPAE had worse 4-year OS (P = 0.001) and higher rates of distant metastasis (P = 0.003) than those who completed planned ICI after developing TRPAE.

CONCLUSION

CRT followed by adjuvant ICI led to improved 4-year OS and PFS consistent with published data. CRTI was associated with higher incidence of grade ≥ 2 TRPAE in both high and low mean lung dose groups without significant difference in grade ≥ 3 TRPAE. Discontinuation of ICI due to TRPAE was associated with poorer OS and distant disease control than completing ICI as planned after developing TRPAE.

Legacy effects of infection in patients with heart failure: a national cohort study of 31,318 patients in Taiwan

Background

Although infection is a common cause of hospitalization in patients (pts) with heart failure (HF), the long-term cardiovascular (CV) prognosis in HF after infection is not well studied.

Methods and results

From 2009 to 2015, 310,485 pts with their first HF admissions and survival to discharge were identified from the National Health Insurance Research Database. Among the pts, 103,505 (33.3%) were readmitted within 1 year after HF discharge for infection, including pneumonia (44.2%), urinary tract infection (UTI) (37.9%), skin and soft tissue infections (9.7%), and others (8.1%). Those without admission for any infection were controls. We compared the primary composite endpoint, including all-cause death, acute myocardial infarction (AMI), stroke, and hospitalization for HF (HHF) between the 2 groups after the infection episode. After propensity score matching, the clinical characteristics (age 71.7±13.9 years, male 52.0%) and treatment were similar between the groups (n=15,659 in each group). In a mean follow-up time of 4.3±2.9 years, 86.2% pts with a history of infection admission and 63.6% pts in the control group met the primary endpoint. Multivariate Cox proportional hazards analysis showed the infection group had a higher risk of the primary composite endpoint (HR 1.760, 95% CI 1.714–1.807), including all-cause death (HR 1.587, 95% CI: 1.540–1.636), HHF (HR 1.993, 95% CI 1.922–2.066), AMI (HR 1.332, 95% CI 1.224–1.450), and stroke (HR 1.769, 95% CI 1.664–1.882). In infection group, HHF was the earliest outcome event with a mean time of 17.5 months and mortality is the second early event with a mean time of 23 months after discharge from the infection episode. Pneumonia carried a higher risk than UTI for the primary composite endpoint (HR 1.140, 95% CI 1.104–1.178).

Conclusions

One-third of HF pts discharged from the hospital experienced acute infection that required readmission. The pts had worse CV prognosis after readmission for infectious disease compared to those without infection

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): This study is supported by National Cheng Kung University Hospital and Tainan Hospital, Ministry of Health and Welfare, Taiwan.

Severe Radiation-Induced Lymphopenia Attenuates the Benefit of Durvalumab After Concurrent Chemoradiotherapy for NSCLC

Introduction

Durvalumab after concurrent chemoradiation (CCRT) for NSCLC improves survival, but only in a subset of patients. We investigated the effect of severe radiation-induced lymphopenia (sRIL) on survival in these patients.

Methods

Outcomes after CCRT (2010–2019) or CCRT followed by durvalumab (2018–2019) were reviewed. RIL was defined by absolute lymphocyte count (ALC) nadir in samples collected at end of CCRT; sRIL was defined as nadir ALC less than 0.23 × 10⁹/L (the lowest tertile). Progression-free survival (PFS) and overall survival (OS) were calculated by the Kaplan-Meier method. Cox proportional hazard modeling evaluated associations between clinical variables and survival.

Results

Of 309 patients, 192 (62%) received CCRT only and 117 (38%) CCRT plus durvalumab. Multivariable logistic regression analysis indicated that sRIL was associated with planning target volume (OR = 1.002, p = 0.001), stage IIIB disease (OR = 2.77, p = 0.04), and baseline ALC (OR = 0.36, p < 0.01). Durvalumab extended median PFS (23.3 versus 14.1 mo, p = 0.003) and OS (not reached versus 30.8 mo, p < 0.01). sRIL predicted poorer PFS and OS in both treatment groups. Among patients with sRIL, durvalumab did not improve survival (median = 24.6 mo versus 18.1 mo CCRT only, p = 0.079). On multivariable analyses, sRIL (OR = 1.81, p < 0.01) independently predicted poor survival.

Conclusions

Severe RIL compromises survival benefits from durvalumab after CCRT for NSCLC. Measures to mitigate RIL after CCRT may be warranted to enhance the benefit of consolidation durvalumab.

Adaptation and dosimetric commissioning of a synchrotron-based proton beamline for FLASH experiments

Objective. Irradiation with ultra-high dose rates (>40 Gy s−1), also known as FLASH irradiation, has the potential to shift the paradigm of radiation therapy because of its reduced toxicity to normal tissues compared to that of conventional irradiations. The goal of this study was to (1) achieve FLASH irradiation conditions suitable for pre-clinical i n vitro and in vivo biology experiments using our synchrotron-based proton beamline and (2) commission the FLASH irradiation conditions achieved. Approach. To achieve these suitable FLASH conditions, we made a series of adaptations to our proton beamline, including modifying the spill length and size of accelerating cycles, repurposing the reference monitor for dose control, and expanding the field size with a custom double-scattering system. We performed the dosimetric commissioning with measurements using an Advanced Markus chamber and EBT-XD films as well as with Monte Carlo simulations. Main results. Through adaptations, we have successfully achieved FLASH irradiation conditions, with an average dose rate of up to 375 Gy s−1. The Advanced Markus chamber was shown to be appropriate for absolute dose calibration under our FLASH conditions with a recombination factor ranging from 1.002 to 1.006 because of the continuous nature of our synchrotron-based proton delivery within a spill. Additionally, the absolute dose measured using the Advanced Markus chamber and EBT-XD films agreed well, with average and maximum differences of 0.32% and 1.63%, respectively. We also performed a comprehensive temporal analysis for FLASH spills produced by our system, which helped us identify a unique relationship between the average dose rate and the dose in our FLASH irradiation. Significance. We have established a synchrotron-based proton FLASH irradiation platform with accurate and precise dosimetry that is suitable for pre-clinical biology experiments. The unique time structure of the FLASH irradiation produced by our synchrotron-based system may shed new light onto the mechanism behind the FLASH effect.

Local Therapy for Oligoprogressive Disease: A Systematic Review of Prospective Trials

OBJECTIVES

The successes of local therapy for oligometastatic cancers cannot be extrapolated to oligoprogressive disease (OPD) because they are distinct clinical entities. Given the limited prospective data on OPD to date, summative analyses are urgently needed.

METHODS

Inclusion criteria for this PRISMA-guided systematic review were as follows. First, only prospective data were included. Second, progression had to have occurred on active/ongoing systemic therapy. Third, the number of progressing areas of disease had to be explicitly listed and ≤5 in number. Fourth, all progressing sites had to undergo local therapy (radiotherapy/surgery/non-radiation ablative procedures).

RESULTS

Eight trials met criteria (summing 290 patients), the vast majority of which utilized stereotactic radiotherapy as the local modality (most commonly, 19-20 Gy in 1 fraction, 27-33 Gy in 3 fractions, or 35-50 Gy in 5 fractions). A study on NSCLC demonstrated that stereotactic radiotherapy improved progression-free survival (PFS) and overall survival compared to historical values with systemic therapy alone. Two additional studies on EGFR-mutated NSCLC also showed acceptable PFS with local therapy, particularly in patients who oligoprogressed on osimertinib. The only randomized trial analyzed herein showed that local therapy improved PFS for NSCLC but not breast cancer. Two trials in castration-resistant prostate cancer illustrated that a substantial proportion of patients did not require any changes in hormonal therapy and/or delayed the need to change systemic therapies. Lastly, two trials of renal cell carcinoma showed high (90-100%) local control and median PFS of 9 months, and potentially a prolonged time to change systemic therapy. Lastly, from all patients in all trials, local therapy was tolerated well, with only 7 instances of grade 3+ toxicities.

CONCLUSIONS

Based on the limited data, local therapy for OPD is safe and yields encouraging short-term preliminary outcomes, but trials with larger sample sizes and longer follow-up are required for more robust conclusions.

Health Care Resource Utilization for Esophageal Cancer Using Proton versus Photon Radiation Therapy

Purpose

In patients treated with chemoradiation for esophageal cancer (EC), randomized trial data demonstrate that proton beam therapy (PBT) reduces toxicities and postoperative complications (POCs) compared with intensity-modulated radiation therapy (IMRT). However, whether radiation therapy modality affects postoperative health care resource utilization remains unknown.

Materials and Methods

We examined 287 patients with EC who received chemoradiation (prescribed 50.4 Gy/GyE) followed by esophagectomy, including a real-world observational cohort of 237 consecutive patients treated from 2007 to 2013 with PBT (n = 81) versus IMRT (n = 156); and an independent, contemporary comparison cohort of 50 patients from a randomized trial treated from 2012 to 2019 with PBT (n = 21) versus IMRT (n = 29). Postoperative complications were abstracted from medical records. Health care charges were obtained from institutional claims and adjusted for inflation (2021 dollars). Charge differences (Δ = $PBT - $IMRT) were compared by treatment using adjusted generalized linear models with the gamma distribution.

Results

Baseline PBT versus IMRT characteristics were not significantly different. In the observational cohort, during the neoadjuvant chemoradiation phase, health care charges were higher for PBT versus IMRT (Δ = +$71,959; 95% confidence interval [CI], $62,274-$82,138; P < .001). There was no difference in surgical charges (Δ = -$2234; 95% CI, -$6003 to $1695; P = .26). However, during postoperative hospitalization following esophagectomy, health care charges were lower for PBT versus IMRT (Δ = -$25,115; 95% CI, -$37,625 to -$9776; P = .003). In the comparison cohort, findings were analogous: Charges were higher for PBT versus IMRT during chemoradiation (Δ = +$61,818; 95% CI, $49,435-$75,069; P < .001), not different for surgery (Δ = -$4784; 95% CI, -$6439 to $3487; P = .25), and lower for PBT postoperatively (Δ = -$27,048; 95% CI, -$41,974 to -$5300; P = .02). Lower postoperative charges for PBT were especially seen among patients with any POCs in the contemporary comparison (Δ = -$176,448; 95% CI, -$209,782 to -$78,813; P = .02).

Conclusion

Higher up-front chemoradiation resource utilization for PBT in patients with EC was partially offset postoperatively, moderated by reduction in POC risks. Results extend existing clinical evidence of toxicity reduction with PBT.

Abstract 6321: Anti-BTN1A1 exhibits synergistic anti-tumor immunotherapeutic efficacy in combination with radiation therapy

Chronic inflammation is a critical risk factor in the context of cancer development that promotes the expression of immune checkpoint proteins including PD-1, PD-L1, LAG-3, and TIM-3, which in turn suppress T-cell mediated cytotoxic tumor cell killing. Inflammation induced by treatments including chemotherapy and radiotherapy (RT) can also promote immune checkpoint upregulation and consequent tumor immune escape. However, whether the acute inflammation associated with standard chemotherapy and RT can engage distinct immune checkpoints to further support tumor persistence remains unknown. Using an in vivo screening platform in which tumors were irradiated with high-dose γ-radiation, we identified the B7-related immunoglobulin superfamily protein butyrophilin 1A1 (BTN1A1) as an acute stress-inducible immune checkpoint. Herein, we aimed to investigate how BTN1A1 contributes to post-irradiation intratumoral immunosuppression. To assess BTN1A1 induction in response to γ-radiation, human cell lines were exposed to a range of radiation doses, and cell death and BTN1A1 expression were examined by flow cytometry. Radiation promoted apoptosis and BTN1A1 expression in a dose-dependent manner, and PD-L1 was downregulated by increasing the dosage of γ-radiation. As radiation-induced cell death results in cytosolic DNA accumulation within tumors, which in turn activates the production of type I interferons (IFNs) via the cGAS/STING pathway, we examined the effect of BTN1A1 on cGAS and STING expression. BTN1A1 overexpression in human prostate adenocarcinoma PC3 cells suppressed cGAS and STING expression. IFNs can promote antigen presenting cell activation, thus priming T cell responses. We then examined the impact of BTN1A1 overexpression on type I IFN production as assessed via qRT-PCR, revealing that BTN1A1 overexpression enhanced IFN-β expression in the presence of the STING agonist cGAMP. BTN1A1 was also found to harbor a C-terminal B30.2 domain that was able to specifically interact with xanthine oxidoreductase (XOR), an oxidizing enzyme involved in purine metabolism. BTN1A1 expression induced high levels of intracellular reactive oxygen species (ROS), which have the potential to be more toxic in lymphocytes as compared to tumor cells, and BTN1A1 knockdown decreased these ROS levels. In light of these observations, we assessed the combination therapeutic efficacy of RT and anti-BTN1A1 antibodies in a syngeneic murine Lewis lung carcinoma (LLC) model system, revealing that these two treatments exhibited synergistic anti-tumor activity. FACS and IHC further confirmed that BTN1A1 was upregulated within tumors following irradiation. Together, these data offer new insights regarding the immunomodulatory role of radiation-induced BTN1A1 within tumors, providing a more robust foundation for the development of BTN1A1 as an immunologic target for cancer therapy.

Citation Format: Ezra Chung, Young-Seung Kim, Andrew Park, Steven H. Lin, Hyunjin Jung, Stephen S. Yoo. Anti-BTN1A1 exhibits synergistic anti-tumor immunotherapeutic efficacy in combination with radiation therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6321.

[Association between periodontitis and mild cognitive impairment: a clinical pilot study]

Objective: To evaluate the association between periodontitis and mild cognitive impairment (MCI), and explore the potential local oral risk factors for MCI. Methods: The study included 70 middle-aged and elderly subjects (44 females and 26 males) with periodontal disease who were first diagnosed by the Department of Periodontology or referred by the Department of Geriatrics in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January 2021 to January 2022. In this study, the control group consisted of periodontal disease patients without cognitive impairment, and the case group (MCI group) consisted of those diagnosed with MCI referred by the geriatrics specialists. Full-mouth periodontal examinations of all subjects were performed and periodontal indicators were recorded by periodontists, while digital panoramic radiographs were taken. The severity of periodontitis was defined according to the 1999 classification, and the staging and grading of periodontitis were defined according to the 2018 American Academy of Periodontology and European Federation of Periodontology classification. The mini-mental state examination scale was chosen by geriatricians to evaluate the cognitive function of the included subjects. The cubital venous blood was drawn to detect the expression levels of inflammatory factors such as hypersensitive C-reactive protein (hs-CRP), interleukin (IL)-1β, IL-6 and tumor necrosis factor-α(TNF-α) in serum. Independent-samples t test and chi-square test were used to analyze the differences in population factors, periodontal-related indexes and serum inflammatory factors between the two groups (α=0.05). Odds ratios (OR) for MCI according to the severity of periodontitis and main periodontal clinical indexes were calculated by binary Logistic analysis. Results: Thirty-nine subjects were included in the control group and thirty-one in the MCI group. The age of the study population was (58.3±6.2) years (range: 45-70 years). The comparison between two groups showed that the control group was with higher educational background (χ²=9.45, P=0.024) and 2.6 years younger than the MCI group [(57.1±6.0) years vs. (59.7±6.3) years, t=-1.24, P=0.082]. The number and proportion of moderate to severe periodontitis in control group were significantly lower compared to those in MCI group (17 cases with 43.6% vs. 23 cases with 74.2%, χ²=6.61, P=0.010), and the OR of moderate to severe periodontitis adjusted by age and educational background was 3.00 (95%CI: 1.01-8.86, P=0.048). Compared with the grading (χ²=5.56, P=0.062) of periodontitis, staging had a greater impact on MCI (χ²=7.69, P=0.041), moreover the proportion of MCI in stage Ⅰ grade A periodontitis was significantly lower than any other type of periodontitis (χ²=13.86, P=0.036). In addition, less presence of deep periodontal pockets [probing depth (PD)≥6 mm] (17.9% vs. 41.9%, χ²=4.87, P=0.027), fewer number of PD≥4 mm (6.48±6.70 vs. 11.03±8.91, t=-2.44, P=0.017), lower plaque index (1.42±0.56 vs. 1.68±0.57, t=-1.91, P=0.059) and gingival index (1.68±0.29 vs. 1.96±0.30, t=-3.93, P<0.001) were in the control group than in the MCI group. However, there were no significant differences between the two groups in the levels of serum inflammatory factors, such as hs-CRP, IL-1β, IL-6 and TNF-α (P>0.05). Conclusions: It appears a strong correlation between moderate to severe periodontitis and the incidence of MCI in middle-aged and elderly people. Moreover, deep and increased number of periodontal pockets, poor oral hygiene, and severe gingival inflammation can be potentially associated risk factors for MCI.

A Systematic Review of Cost-Effectiveness Studies of Stereotactic Radiotherapy for Cancer Oligometastases

PURPOSE

It is crucial to economically justify the use of promising therapies such as stereotactic ablative radiotherapy (SABR) for oligometastatic disease (OMD). The goal of this systematic review was to summatively evaluate publications that analyzed the cost-effectiveness of SABR for OMD.

METHODS AND MATERIALS

Using PRISMA-guided methodology, PubMed and EMBASE were searched for modeling-based cost effectiveness (CE) studies for various forms of limited metastatic disease. Only full publications that specifically compared SABR with a systemic therapy-based approach were included.

RESULTS

Of 9 studies, 4 pertained to OMD with mixed histologies, 2 to oligometastatic non-small cell lung cancer, 1 to pulmonary OMD, 1 to liver OMD, and 1 to low-volume oligorecurrent castration-sensitive prostate cancer. All but one investigation illustrated that SABR was cost-effective for the studied population (or a subpopulation); of these studies, the incremental CE ratios (ICERs) for SABR (when reported) ranged from $28,000/quality-adjusted life-year (QALY) to $55,000/QALY. Of studies that reported the probability of SABR being cost-effective at common willingness-to-pay values, the median (range) probability of achieving CE was roughly 61% (30-88%) at a $50,000/QALY threshold and 78% (31%-100%) at a $100,000/QALY threshold.

CONCLUSIONS

The available evidence suggests that SABR is a cost-effective approach for OMD, which has implications for value-based oncologic practice and construction of future health policies. However, re-assessment is required in the context of modern systemic therapies (e.g. immunotherapy) as well as long-term follow-up of existing and newly reported randomized trials. Prudent patient selection remains the single most important factor influencing the CE of SABR for OMD.

Treatment patterns and outcomes in resectable early stage NSCLC: Interim analysis of a global real-world study

e18803

Background: Complete surgical resection is the preferred treatment for early stage NSCLC, with adjuvant chemotherapy as the standard of care in resected stage II/III and select stage IB NSCLC. Osimertinib, an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), is approved as adjuvant therapy in patients (pts) with resected stage IB–IIIA EGFR mutation-positive (EGFRm) NSCLC following results from the Phase III ADAURA trial. Understanding real-world clinical outcomes in early stage NSCLC, including EGFRm prevalence, will help inform unmet needs and further development of new treatment strategies in this population. We report interim results from a global non-interventional retrospective study of pts with resectable NSCLC using clinical data from medical records. Methods: Eligible pts (aged ≥18 yrs) had completely resected stage IA–IIIA NSCLC diagnosed between Jan 1, 2014 and Dec 31, 2017 with EGFR test results available and were followed to at least Dec 31, 2020. Primary endpoints included EGFRm prevalence, treatment patterns, and overall survival (OS); disease-free survival (DFS) was an exploratory endpoint estimated by Kaplan-Meier at predefined landmark timepoints. Results: Of 463 pts from 6 countries (31% from Taiwan, 21% Canada, 17% US, 13% Austria, 10% South Korea, 9% France), median age was 66 yrs (range: 33–86); 172 pts (37%) had stage IA NSCLC at initial diagnosis and 291 (63%) had stage IB–IIIA (22% IB, 13% IIA, 10% IIB, 18% IIIA). 213/463 pts (46%) were EGFRm (43% stage IA, 61% IB, 43% IIA, 26% IIB, 47% IIIA), of who 46% were from Taiwan, 21% South Korea, 14% Austria, 8% Canada, 7% US, and 4% France. In pts with EGFRm vs EGFR wild-type (wt) NSCLC, 84/213 (39%) and 83/250 (33%), respectively, received (neo)adjuvant therapy, of who 156/167 pts (93%) had stage IB–IIIA NSCLC. 106/156 pts (68%) had disease recurrence or death from time of surgery; recurrence rates were similar in pts with EGFRm vs EGFRwt NSCLC, though median DFS was longer in the EGFRm group (Table). Recurrence rates were high in both EGFRm and EGFTwt groups, with landmark DFS probability of 72% vs 77% at 12 mo and 29% vs 32% at 60 mo, respectively. Conclusions: In this real-world global study of surgically resected stage IA–IIIA NSCLC in pts who received an EGFR test, nearly half of the study cohort were EGFRm positive, of who 70% were treated in Taiwan/South Korea. The high rate of recurrence in pts with stage IB–IIIA NSCLC despite receiving (neo)adjuvant therapy reinforces the need for early diagnosis and EGFR testing to identify pts who might benefit from EGFR-targeted therapy, helping optimize clinical outcomes.[Table: see text]

Deep learning signature from chest CT and association with immunotherapy outcomes in EGFR/ALK-negative NSCLC

9061

Background: Many clinicopathological and molecular features are associate with clinical benefit from immune checkpoint inhibitors (ICIs) for patients with non-small-cell lung cancer (NSCLC), yet none was exclusive underscoring the heterogeneity of lung cancers. As images may provide a holistic view of cancer, we attempted deep learning to chest CT scans to derive a predictor of response to ICIs and test its benefit relative to known clinicopathological factors. Methods: 928 stage IV, EGFR/ALK-negative NSCLC patients treated with ICIs alone or in combination (MD Anderson GEMINI Database) were divided into training (CTtr = 572), validation (CTva = 78), and testing (CTte = 278) cohorts, balancing the distribution of clinicopathological and radiological factors. Progression-free (PFS) and overall survival (OS) were defined as outcomes. We analyzed whole lung, including tumor and normal parenchyma of chest CT images ≤ 3 months prior to ICI treatment. An ensemble learning model (CT-deep-learning) to clustering patients into high vs low risk groups of PFS or OS was developed by fusing risk scores from four independent deep learning networks (supervised, unsupervised, and hybrid). This CT-deep-learning model was further evaluated in different clinicopathological subgroups. Finally, a composite model (CT-Clinic-path) was built by combining image model with clinicopathological factors. Antolini's concordance index (C-index) was used to assess model performance. Results: Median PFS and OS were shorter in the high-risk vs low-risk group as defined by CT-deep-learning: PFS (CTtr: 4.2 vs 9.6 mons; HR 1.96; 95% CI 1.62-2.38; P < 0.0001; CTva: 3.7 vs 10.2 mons; HR 2.32; 95% CI 1.32-4.07; P = 0.0025; CTte: 3.6 vs 9.1 mons; HR 1.89; 95% CI 1.39-2.56; P < 0.0001) and OS (CTtr: 16.0 vs 31.4 mons; HR 2.19; 95% CI 1.72-2.79; P < 0.0001; CTva: 12.7 vs 28.6 mons; HR 2.01; 95% CI 1.04-3.88; P = 0.035; CTte: 14.8 vs 32.0 mons; HR 1.84; 95% CI 1.31-2.60; P = 0.0004). CT-deep-learning outperformed clinicopathologic features known to associate with ICI benefit, such as histology, smoking status, PD-L1 expression, and remained to be an independent (P < 0.001) prognostic factor on multivariate analysis. Furthermore, integrating CT-deep-learning to clinicopathological variables improved prediction performance with a net reclassification up to 7% (Clinic-path model, C-indices 0.60 – 0.62 vs CT-clinic-path model, 0.64 - 0.65 for PFS; Clinic-path model 0.64 – 0.67 vs CT-clinic-path model 0.69 – 0.71 for OS). Conclusions: We have developed and validated a deep learning signature associated with PFS and OS in ICI-treated NSCLC patients, which appears to be independent of and superior to known clinicopathological biomarkers. If validated, this signature may strengthen the predictive value of clinicopathological factors and facilitate selecting appropriate patients for ICI-based therapies.

Monitoring PD-L1 expression on circulating stromal cells in blood predicts PFS and OS in patients with metastatic NSCLC treated with PD-L1/PD-1 immunotherapy

8535

Background: Cancer Associated Macrophage Like cells (CAMLs), a circulating stromal cell found in cancer patients (pts) blood, are phagocytic giant macrophages that appear to parallel the inflammatory PD-L1 state of the tumor microenvironment. Previously, we demonstrated in local non-small cell lung carcinoma (NSCLC), CAML PD-L1 expression is dynamic and predicts response to PD-L1/PD-1 immunotherapies (IMTs) following sequential sampling before and after chemotherapy (chemo) induction (̃30days) based on progression free (PFS) & overall survival (OS). However this has not been tested in metastatic NSCLC (mNSCLC). Here,we report the results of monitoring PD-L1 expression in CAMLs before and after chemo induction (̃30 days) to evaluate its predictive value in mNSCLC pts treated with or without IMT. Methods: A single blind multi-year prospective study was undertaken to test the relationship of PD-L1 expression in CAMLs to PFS & OS, pre & post chemo induction, in recurrent mNSCLC with (n = 41) or without (n = 41) additional anti-PD-L1/PD-1 IMTs. This included three IMTs: atezolizumab (n = 4), nivolumab (n = 8) or pembrolizumab (n = 29). We recruited 82 pts with pathologically confirmed recurrent mNSCLC prior to treatment for newly recurrent metastatic disease. Blood samples (15 mL) were taken at Baseline (BL), prior to chemo, and ̃30 days after chemotherapy (T1). Blood was filtered by CellSieve filtration & CAMLs’ expression scored as a binary high/low, to evaluate PFS & OS hazard ratios (HRs) by censored univariate & multivariate analysis at 18 months. Results: CAMLs were found in 97% of all tested samples, 94% at BL & 100% at T1. CAML PD-L1 at BL was found not to be associated with PFS or OS in pts treated with chemo alone (PFS p = 0.620 & OS p = 0.673) or chemo+IMT (PFS p = 0.353 & OS = 0.477) at 18 months. At T1, high CAML PD-L1 in pts treated with chemo alone had no significantly different PFS (HR = 1.3, p = 0.694) or OS (HR = 1.6 p = 0.503). However, high CAML PD-L1 at T1 in pts treated with chemo+IMT had significantly better PFS (HR = 3.1, 95%CI = 1.3-7.3, p = 0.019), and OS (HR = 3.4, 95%CI = 1.4-8.3, p = 0.014). Further subtyping & analysis is ongoing to evaluate PFS and OS at 24 months. Conclusions: Our data suggests that in mNSCLC, PD-L1 expression in circulating CAMLs dynamically upregulates after induction with chemotherapy and appears to predict patients with increased benefit to PD-L1/PD-1 IMTs, though additional studies are needed to validate these findings.

Real-world effectiveness of immune checkpoint inhibitors alone or in combination with chemotherapy in metastatic non–small cell lung cancer

9055

Background: The benefit of combination immune checkpoint inhibitor (ICI) with chemotherapy over ICI monotherapy in non-small cell lung cancer (NSCLC) remains underexplored. Methods: This retrospective cohort included patients with metastatic NSCLC from a single-institution database treated with ICI monotherapy or with chemotherapy between 1/2014-2/2020. Clinical progression-free survival (PFS) and overall survival (OS) were the primary outcomes. Propensity score adjustment for clinical and sociodemographic characteristics was used for analysis of first-line treatment outcomes. Results: A total of 1,139 patients (54% male; median age, 64.9) were included. Adenocarcinoma histology, smoking history, higher PD-L1 expression, and lower metastatic stage associated with improved PFS. However, PD-L1 expression and smoking associated with PFS only in adenocarcinoma (LUAD); squamous (LUSC) patients had shorter PFS independent of PD-L1 and smoking history (PD-L1 > 50% vs 1-49%: LUAD P < 0.001; LUSC P = 0.69; Former vs never smoker: LUAD P = 0.008; LUSC P = 0.89). In first-line patients (n = 680), treatment with ICI plus chemotherapy (ICI-chemo) associated with higher progression-free rates at 3 and 6 months compared with ICI-monotherapy (ICI-chemo vs ICI-mono: 3-month PFS, 85.2% vs 68.8%, P = 0.001; 6-month PFS, 66.4% vs 52.6%, P = 0.008). However, there was no difference overall in PFS or OS in either the full or propensity-matched cohort. Treatment with ICI and chemotherapy concurrently vs sequentially was associated with similar PFS (log-rank P = 0.12). Conclusions: In this real-world cohort, the addition of chemotherapy to ICIs may protect against early progression but does not influence long-term outcomes. Treatment with sequential vs concurrent ICI and chemotherapy produced similar outcomes. These findings suggest that combination therapy may maximally benefit patients at risk of early progression.

Safety results of NRG-LU004: Phase I trial of accelerated or conventionally fractionated radiotherapy combined with durvalumab in PD-L1–high locally advanced non-small cell lung cancer

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Background: In advanced non-small cell lung cancer (NSCLC), high Programmed-Death-1 Ligand (PD-L1) (>50%) expression demonstrate superior response and survival with immune checkpoint inhibitors compared to chemotherapy. We hypothesize that it is safe and feasible to substitute durvalumab instead of chemotherapy concurrently with radiotherapy (RT) in patients with Locally Advanced-NSCLC (LA-NSCLC) and high PD-L1. Methods: NRG-LU004 (NCT03801902) is a Phase I study for patients with stage II-III unresectable or inoperable, LA-NSCLC with PD-L1> 50% (Dako 22C3 or Ventana SP263) expression. There were safety and expansion phases with a primary endpoint of safety. Patients started with 1500 mg durvalumab Q4 weeks and thoracic RT within 2 weeks from 1st infusion. Durvalumab continued once a month up to 1 year. In the safety cohort, 6 patients in cohort 1 were treated with accelerated fractionated RT (ACRT) to 60 Gy in 15 fractions, followed by a required safety hold for 90 days. During cohort 1 safety hold, cohort 2 patients were treated with conventional RT 60 Gy in 30 fractions (CONV) followed by a 60-day safety hold. A cohort advanced to the expansion phase to enroll 6 more patients if safety criteria (0-1 patients with a dose limiting toxicity [DLT]) were met. If both cohorts were deemed safe, patients would be randomized 1:1 to ACRT or CONV with safety defined as < 4 of 12 evaluable patients per arm experiencing a DLT. Feasibility was defined as at least 80% of patients in each arm receiving at least 80% of the planned dose of durvalumab during the first 8 weeks. Results: 24 evaluable patients enrolled between January 2019 and June 2021. No DLTs were reported in cohort 1, and 1 (unrelated bronchopulmonary hemorrhage leading to discontinuation of durvalumab) in cohort 2. Both safety cohorts advanced to the expansion phase. All but one patient (CONV) received RT per protocol/with an acceptable variation. At the time of analysis, 24% had received all 13 cycles of durvalumab. For the ACRT cohort, there were 4 grade 3, 1 grade 4 (lymphopenia), and 1 grade 5 AE (lung infection, assessed as unrelated to therapy). For CONV, there were 8 grade 3, 0 grade 4, and 1 grade 5 AE (respiratory failure, unrelated to therapy). For feasibility, 10 of 12 (85%) patients in the ACRT cohort received the second dose of durvalumab (2 not received due to shingles and unrelated death), while 9 of 12 (75%) of the CONV cohort received the second dose (reasons for not receiving: viral hepatitis, bronchopulmonary hemorrhage, and respiratory failure, all assessed as unrelated to therapy). Conclusions: Chemotherapy-free thoracic RT approaches (ACRT or CONV RT) are safe, when given with concurrent durvalumab in patients with PD-L1 high LA-NSCLC. A trial to compare immunoradiotherapy and consolidation durvalumab to standard chemoradiation and consolidation durvalumab is planned. Clinical trial information: NCT03801902.