Nucleus-mitochondria positive feedback loop formed by ERK5 S496 phosphorylation-mediated poly (ADP-ribose) polymerase activation provokes persistent pro-inflammatory senescent phenotype and accelerates coronary atherosclerosis after chemo-radiation

The incidence of cardiovascular disease (CVD) is higher in cancer survivors than in the general population. Several cancer treatments are recognized as risk factors for CVD, but specific therapies are unavailable. Many cancer treatments activate shared signaling events, which reprogram myeloid cells (MCs) towards persistent senescence-associated secretory phenotype (SASP) and consequently CVD, but the exact mechanisms remain unclear. This study aimed to provide mechanistic insights and potential treatments by investigating how chemo-radiation can induce persistent SASP. We generated ERK5 S496A knock-in mice and determined SASP in myeloid cells (MCs) by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. Candidate SASP inducers were identified by high-throughput screening, using the ERK5 transcriptional activity reporter cell system. Various chemotherapy agents and ionizing radiation (IR) up-regulated p90RSK-mediated ERK5 S496 phosphorylation. Doxorubicin and IR caused metabolic changes with nicotinamide adenine dinucleotide depletion and ensuing mitochondrial stunning (reversible mitochondria dysfunction without showing any cell death under ATP depletion) via p90RSK-ERK5 modulation and poly (ADP-ribose) polymerase (PARP) activation, which formed a nucleus-mitochondria positive feedback loop. This feedback loop reprogramed MCs to induce a sustained SASP state, and ultimately primed MCs to be more sensitive to reactive oxygen species. This priming was also detected in circulating monocytes from cancer patients after IR. When PARP activity was transiently inhibited at the time of IR, mitochondrial stunning, priming, macrophage infiltration, and coronary atherosclerosis were all eradicated. The p90RSK-ERK5 module plays a crucial role in SASP-mediated mitochondrial stunning via regulating PARP activation. Our data show for the first time that the nucleus-mitochondria positive feedback loop formed by p90RSK-ERK5 S496 phosphorylation-mediated PARP activation plays a crucial role of persistent SASP state, and also provide preclinical evidence supporting that transient inhibition of PARP activation only at the time of radiation therapy can prevent future CVD in cancer survivors.

Simple oligonucleotide-based multiplexing of single-cell chromatin accessibility

Microdroplet single-cell ATAC-seq is widely used to measure chromatin accessibility, however, highly scalable and simple sample multiplexing procedures are not available. Here, we present a transposome-assisted single nucleus barcoding approach for ATAC-seq (SNuBar-ATAC) that utilizes a single oligonucleotide adaptor for multiplexing samples during the existing tagmentation step and does not require a pre-labeling procedure. The accuracy and scalability of SNuBar-ATAC was evaluated using cell line mixture experiments. We applied SNuBar-ATAC to investigate treatment-induced chromatin accessibility dynamics by multiplexing 28 mice with lung tumors that received different combinations of chemo, radiation, and targeted immunotherapy. We also applied SNuBar-ATAC to study spatial epigenetic heterogeneity by multiplexing 32 regions from a human breast tissue. Additionally, we show that SNuBar can multiplex single cell ATAC and RNA multiomic assays in cell lines and human breast tissue samples. Our data show that SNuBar is a highly accurate, easy-to-use, and scalable system for multiplexing scATAC-seq and scATAC and RNA co-assay experiments.

Current status and application of proton therapy for esophageal cancer

Esophageal cancer remains one of the leading causes of death from cancer across the world despite advances in multimodality therapy. Although early-stage disease can often be treated surgically, the current state of the art for locally advanced disease is concurrent chemoradiation, followed by surgery whenever possible. The uniform midline tumor location puts a strong importance on the need for precise delivery of radiation that would minimize dose to the heart and lungs, and the biophysical properties of proton beam makes this modality potential ideal for esophageal cancer treatment. This review covers the current state of knowledge of proton therapy for esophageal cancer, focusing on published retrospective single- and multi-institutional clinical studies, and emerging data from prospective clinical trials, that support the benefit of protons vs photon-based radiation in reducing postoperative complications, cardiac toxicity, and severe radiation induced immune suppression, which may improve survival outcomes for patients. In addition, we discuss the incorporation of immunotherapy to the curative management of esophageal cancers in the not-too-distant future. However, there is still a lack of high-level evidence to support proton therapy in the treatment of esophageal cancer, and proton therapy has its limitations in clinical application. It is expected to see the results of future large-scale randomized clinical trials and the continuous improvement of proton radiotherapy technology.

Exploring the synergy of radiative coupling and substrate undercut in arrayed gold nanodisks for economical, ultra-sensitive label-free biosensing

We report radiatively coupled arrayed gold nanodisks on invisible substrate (AGNIS) as a cost-effective, high-performance platform for nanoplasmonic biosensing. By substrate undercut, the electric field distribution around the nanodisks has been restored to as if the nanodisks were surrounded by a single medium, thereby provides analyte accessibility to otherwise buried enhanced electric field. The AGNIS substrate has been fabricated by wafer-scale nanosphere lithography without the need for costly lithography. The LSPR blue-shifting behavior synergistically contributed by radiative coupling and substrate undercut have been investigated for the first time, which culminates in a remarkable refractive index sensitivity increase from 207 nm/RIU to 578 nm/RIU. The synergy also improves surface sensitivity to monolayer neutravidin-biotin binding from 7.4 nm to 20.3 nm with the limit of detection (LOD) of neutravidin at 50 fM, which is among the best label-free results reported to date on this specific surface binding reaction. As a potential cancer diagnostic application, extracellular vesicles such as exosomes excreted by cancer and normal cells were measured with a LOD within 112-600 (exosomes/μL), which would be sufficient in many clinical applications. Using CD9, CD63, and CD81 antibodies, label-free profiling has shown increased expression of all three surface antigens in cancer-derived exosomes. This work demonstrates, for the first time, strong synergy of arrayed radiative coupling and substrate undercut can enable economical, ultrasensitive biosensing in the visible light spectrum where high-quality, low-cost silicon detectors are readily available for point-of-care applications.

Identifying Individualized Risk Profiles for Radiotherapy-Induced Lymphopenia Among Patients With Esophageal Cancer Using Machine Learning

PURPOSE

Radiotherapy (RT)-induced lymphopenia (RIL) is commonly associated with adverse clinical outcomes in patients with cancer. Using machine learning techniques, a retrospective study was conducted for patients with esophageal cancer treated with proton and photon therapies to characterize the principal pretreatment clinical and radiation dosimetric risk factors of grade 4 RIL (G4RIL) as well as to establish G4RIL risk profiles.

METHODS

A single-institution retrospective data of 746 patients with esophageal cancer treated with photons (n = 500) and protons (n = 246) was reviewed. The primary end point of our study was G4RIL. Clustering techniques were applied to identify patient subpopulations with similar pretreatment clinical and radiation dosimetric characteristics. XGBoost was built on a training set (n = 499) to predict G4RIL risks. Predictive performance was assessed on the remaining n = 247 patients. SHapley Additive exPlanations were used to rank the importance of individual predictors. Counterfactual analyses compared patients' risk profiles assuming that they had switched modalities.

RESULTS

Baseline absolute lymphocyte count and volumes of lung and spleen receiving ≥ 15 and ≥ 5 Gy, respectively, were the most important G4RIL risk determinants. The model achieved sensitivitytesting-set 0.798 and specificitytesting-set 0.667 with an area under the receiver operating characteristics curve (AUCtesting-set) of 0.783. The G4RIL risk for an average patient receiving protons increased by 19% had the patient switched to photons. Reductions in G4RIL risk were maximized with proton therapy for patients with older age, lower baseline absolute lymphocyte count, and higher lung and heart dose.

CONCLUSION

G4RIL risk varies for individual patients with esophageal cancer and is modulated by radiotherapy dosimetric parameters. The framework for machine learning presented can be applied broadly to study risk determinants of other adverse events, providing the basis for adapting treatment strategies for mitigation.

Biology of the Radio- and Chemo-Responsiveness in HPV Malignancies

In multiple anatomic sites, patients with cancers associated with the Human Papillomavirus (HPV) experience better locoregional control and overall survival after radiotherapy and/or chemoradiotherapy than patients with HPV-negative cancers. These improved outcomes suggest that relatively unique biological features in HPV-positive cancers may increase sensitivity to DNA damaging agents as well as an impaired DNA damage response. This review will address potential biological mechanisms driving this increased sensitivity of HPV-positive cancer to radiation and/or chemotherapy. This review will discuss the clinical and preclinical observations that support the intrinsic radiosensitivity and/or chemosensitivity of HPV-positive cancers. Furthermore, this review will highlight the molecular mechanisms for increased radiation sensitivity using the classical "4 Rs" of radiobiology: repair, reassortment, repopulation, and reoxygenation. First, HPV-positive cancers have increased DNA damage due to increased oxidative stress and impaired DNA damage repair due to the altered activity TP53, p16, TIP60, and other repair proteins. Second, irradiated HPV-positive cancer cells display increased G2/M arrest leading to reassortment of cancer cells in more radiosensitive phases of the cell cycle. In addition, HPV-positive cancers have less radioresistant cancer stem cell subpopulations that may limit their repopulation during radiotherapy. Finally, HPV-positive cancers may also have less hypoxic tumor microenvironments that make these cancers more sensitive to radiation than HPV-negative cells. We will also discuss extrinsic immune and microenvironmental factors enriched in HPV-positive cancers that facilities responses to radiation. Therefore, these potential biological mechanisms may underpin the improved clinical outcomes often observed in these virally induced cancers.

Severe lymphopenia acquired during chemoradiotherapy for esophageal cancer: Incidence and external validation of a prediction model

BACKGROUND

The incidence of grade 4 lymphopenia in patients treated with chemoradiotherapy (CRT) according to Chemoradiotherapy for Oesophageal cancer followed by Surgery Study (CROSS) regimen is unclear. The primary aim was to determine the incidence of grade 4 lymphopenia during CROSS for esophageal cancer. Secondary aims were to externally validate a prediction model for grade 4 lymphopenia and compare overall survival between patients with and without grade 4 lymphopenia.

METHODS

Patients who underwent CRT for esophageal cancer between 2014 and 2019 were eligible for inclusion. Patients with a planned radiation dose of 41.4 Gy (CROSS) or 50.4 Gy ("extended-CROSS") and concurrent carboplatin and paclitaxel were included. The primary outcome was the incidence of grade 4 lymphopenia during CRT defined according to Common Terminology Criteria for Adverse Events version 5.0 (i.e. lymphocyte count nadir < 0.2 µL). The secondary outcome measures were the prediction model's external performance (i.e. discrimination and calibration). Overall survival for patients with versus without grade 4 lymphopenia was compared using Kaplan-Meier analysis.

RESULTS

A total of 219 patients were included of whom 176 patients (80%) underwent CROSS and 43 patients (20%) extended-CROSS. The incidence of grade 4 lymphopenia was 11% in CROSS and 33% in extended-CROSS (p < 0.001). External discrimination yielded a c-statistic of 0.80 (95% confidence interval: 0.70-0.89). External calibration of the model was poor in CROSS but fair in extended-CROSS. Adjusted calibration using intercept correction (adjusted for the lower a-priori risk for grade 4 lymphopenia in CROSS) showed fair agreement between the observed and predicted risk for grade 4 lymphopenia. Median overall survival in patients with versus without grade 4 lymphopenia was 12.7 versus 42.5 months (p = 0.045).

CONCLUSION

The incidence of grade 4 lymphopenia is significantly higher in esophageal cancer patients receiving extended-CROSS compared to those receiving CROSS. The prediction model demonstrated good external performance in the setting of the CROSS-regimen and could be used to identify patients at high-risk for grade 4 lymphopenia who might be eligible for lymphopenia-mitigating strategies.

Moving Beyond the Standard of Care: Accelerate Testing of Radiation-Drug Combinations

Radiation therapy is a major treatment modality used in > 60% of cancer patients as definitive local treatment for inoperable locoregionally confined tumors and as palliative therapy. Although cytotoxic chemotherapy enhances the effectiveness of treatment, the benefit over radiation therapy alone is modest. There is a need to enhance the effectiveness of local tumor control over what sequentially or concurrently administered cytotoxic chemotherapy provides. Although many biological pathways are known to enhance the effectiveness of radiation therapy, there is currently a paucity of drugs approved for use in combination. Several clinical trials have tested the effectiveness of combining targeted agents or immunotherapies with radiation therapy, but the results of these trials have been negative, likely stemming from the relative lack of preclinical evidence using appropriate experimental standardization or model systems. Accelerating the identification of agents tested in an appropriate clinical context and experimental systems or models would greatly enhance the potential to bring forward early testing of drugs that would not only be safe but also more effective. This article provides an overview of the opportunities and challenges of developing therapeutics to combine with radiation therapy, and some guidance toward preclinical and early clinical testing to improve the chance that advanced phase testing of drug-radiation combinations would be successful in the long term.

Screening and Validation of Molecular Targeted Radiosensitizers

The development of molecular targeted drugs with radiation and chemotherapy are critically important for improving the outcomes of patients with hard-to-treat, potentially curable cancers. However, too many preclinical studies have not translated into successful radiation oncology trials. Major contributing factors to this insufficiency include poor reproducibility of preclinical data, inadequate preclinical modeling of inter-tumoral genomic heterogeneity that influences treatment sensitivity in the clinic, and a reliance on tumor growth delay instead of local control (TCD50) endpoints. There exists an urgent need to overcome these barriers to facilitate successful clinical translation of targeted radiosensitizers. To this end, we have employed 3D cell culture assays to better model tumor behavior in vivo. Examples of successful prediction of in vivo effects with these 3D assays include radiosensitization of head and neck cancers by inhibiting epidermal growth factor receptor or focal adhesion kinase signaling, and radioresistance associated with oncogenic mutation of KRAS. To address the issue of tumor heterogeneity we leveraged institutional resources that allow high-throughput 3D screening of radiation combinations with small molecule inhibitors across genomically characterized cell lines from lung, head and neck, and pancreatic cancers. This high-throughput screen is expected to uncover genomic biomarkers that will inform the successful clinical translation of targeted agents from the NCI CTEP portfolio and other sources. Screening "hits" need to be subjected to refinement studies that include clonogenic assays, addition of disease-specific chemotherapeutics, target/biomarker validation, and integration of patient-derived tumor models. The chemoradiosensitizing activities of the most promising drugs should be confirmed in TCD50 assays in xenograft models with/without relevant biomarker and utilizing clinically relevant radiation fractionation. We predict that appropriately validated and biomarker-directed targeted therapies will have a higher likelihood than past efforts to be successfully incorporated into the standard management of hard-to-treat tumors.

Care Patterns for Stereotactic Radiosurgery in Small Cell Lung Cancer Brain Metastases

INTRODUCTION

The historical standard of care for brain metastases (BMs) from small cell lung cancer (SCLC) has been whole-brain radiotherapy (WBRT). However, there is growing interest in upfront stereotactic radiosurgery (SRS) for select SCLC patients.

MATERIALS AND METHODS

We invited United State-based Radiation Oncologists (ROs) via email to answer an anonymous survey using a branching logic system addressing their use of SRS and WBRT for SCLC BMs. Wilcoxon rank-sum test and Fisher's exact test were used to compare differences in continuous and categorical variables, respectively. Multivariable logistic regression analyses were fitted for outcome variables including covariates with P < .10 obtained on univariable analysis.

RESULTS

In total, 309 ROs completed the survey and 290 (95.7%) reported that they would consider SRS for SCLC BMs under certain clinical circumstances. Across patient characteristics, the number of BMs was the most heavily weighted factor (mean 4.3/5 in importance), followed by performance status, cognitive function, and response to prior therapy. Fewer BMs were correlated with increased SRS use (55.8% offered SRS "very frequently" [>75% of cases] or "often" [51%-75% of cases] for 1 BM vs. 1.1% for >10 BM, P < .001). In situations where WBRT was preferred, concern for rapid intracranial progression (45.3%) and lack of high-level data (36.9%) were the most important factors. The majority (60.6%) were aware of a large recent international retrospective analysis (the FIRE-SCLC study) reporting similar OS between upfront SRS and WBRT; awareness of this study was the only respondent variable predictive of SRS use for limited BMs (19.2% of those aware of the study preferring SRS for limited [≤4] BMs before vs. 61% preferring SRS after the publication, P < .001). The majority of respondents (88.2%) expressed a willingness to enroll patients on a recently opened recently opened randomized trial, NRG-CC009, comparing SRS versus hippocampal-avoidance WBRT.

CONCLUSIONS

In the first survey of SRS for SCLC BMs, we observed a high level of physician openness to upfront SRS in SCLC, particularly for patients with limited numbers of BMs, as well as significant interest in generating prospective randomized data to clarify the role of SRS in this population.

Assessment of Prognostic Value of High-Sensitivity Cardiac Troponin T for Early Prediction of Chemoradiation Therapy-Induced Cardiotoxicity in Patients with Non-Small Cell Lung Cancer: A Secondary Analysis of a Prospective Randomized Trial

PURPOSE

Cardiotoxicities induced by cancer therapy can negatively affect quality of life and survival. We investigated whether high-sensitivity cardiac troponin T (hs-cTnT) levels could serve as biomarker for early detection of cardiac adverse events (CAEs) after chemoradiation therapy (CRT) for non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

This study included 225 patients who received concurrent platinum and taxane-doublet chemotherapy with thoracic radiation therapy to a total dose of 60 to 74 Gy for NSCLC. All patients were evaluated for CAEs; 190 patients also had serial hs-cTnT measurements.

RESULTS

Grade ≥3 CAEs occurred in 24 patients (11%) at a median interval of 9 months after CRT. Pretreatment hs-cTnT levels were higher in men, in patients aged ≥64 years, and in patients with pre-existing heart disease or poor performance status (P < .05). hs-cTnT levels increased at 4 weeks during CRT (P < .05) and decreased after completion of CRT but did not return to pretreatment levels (P = .002). The change (Δ) in hs-cTnT levels during CRT correlated with mean heart dose (P = .0004), the heart volumes receiving 5 to 55 Gy (P < .05), and tumor location (P = .006). Risks of severe CAEs and mortality were significantly increased if the pretreatment hs-cTnT was >10 ng/L or the Δ during CRT was ≥5 ng/L.

CONCLUSIONS

Elevation of hs-cTnT during CRT was radiation heart dose-dependent, and high hs-cTnT levels during the course of CRT were associated with CAEs and mortality. Routine monitoring of hs-cTnT could identify patients who are at high risk of CRT-induced CAEs early to guide modifications of cancer therapy and possible interventions to mitigate cardiotoxicity.

Abstract 1643: BTN1A1: a novel immune checkpoint for cancer immunotherapy beyond the PD-1/PD-L1 axis

Cancer immunotherapy is an effective treatment against individuals with late-stage cancer forms. The PD-1/PD-LI axis is a main therapeutic target used in clinical settings, but only 15-20% of cancer patients are responsive. Thus, there is an urgent unmet need to identify other immuno-therapeutic targets to overcome this limitation. Butyrophilin (BTN) belongs to the B7 family, peripheral membrane proteins containing an immunoglobulin domain found in PD-L1 and CTLA4. Among the BTN family, BTN2A2 and BTN3A1 are shown as alternative co-inhibitory or co-stimulatory cancer immune checkpoint(s) in the effector T cell compartment. However, the immune-modulatory roles of BTN1A1 are largely unknown, especially in vivo. Here, we report the immune-modulatory role of BTN1A1 in T cell proliferation and activation in vitro and in vivo. We have found that BTN1A1 inhibits the proliferation of T cells that are activated by anti-CD3 and anti-CD28 antibodies in vitro. The overexpression of BTN1A1 in PC3 cells also inhibits T cell-mediated cancer cell killing. BTN1A1-overexpressing B16-Ova melanoma cancer cell lines also accelerate tumor growth compared to B16-Ova wild type in a syngeneic mouse model. The effect of BTN1A1 was fully attenuated in an immune-compromised SCID mouse. BTN1A1-deficient MC38 colorectal cancer cell lines also grew significantly slower than wild-type MC38 cell lines when they were inoculated subcutaneously into a syngeneic mouse model. This result strongly supports BTN1A1's role in immune evasion. BTN1A1 is expressed on immune cells. These cells include macrophages, B cells or activated CD8 T cells. We found that BTN1A1 is expressed in human tumors, with an expression that was mutually exclusive to PD-L1. We have developed the monoclonal antibody (STC810) against the human BTN1A1. STC810 has anti-tumor activity in a human immune environment in vitro and ex vivo. Since STC810 has no cross-reactivity with mouse BTN1A1 proteins, we generated mouse surrogate antibodies to study the effects of blocking BTN1A1 in vivo in mice tumor models. The anti-BTN1A1 surrogate antibody not only exhibits a single agent but has a synergistic effect in combination with the anti-PD-L1 antibody. Overall, using mouse models, genetic ablation, and antibody tests ex vivo we demonstrate that BTN1A1 is a bona fide immune checkpoint inhibitor. Late-stage preclinical studies of humanized STC810 are underway. The Phase I clinical trial is set to start in late 2021.

Citation Format: Ezra M. Chung, Yong-Sik Bong, Young-Seung Kim, Andrew Park, Young-Ok You, Amrish Sharma, Steven H. Lin, Young-Joon Lee, Hyunjin Jung, Stephen S. Yoo. BTN1A1: a novel immune checkpoint for cancer immunotherapy beyond the PD-1/PD-L1 axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1643.

Factors Associated With Age Disparities Among Cancer Clinical Trial Participants

Importance

Seminal investigation 2 decades ago alerted the oncology community to age disparities in participation in cooperative group trials; less is known about whether these disparities persist in industry-funded research.

Objective

To characterize the age disparities among trial enrollees on randomized clinical trials (RCTs) of common cancers in clinical oncology and identify factors associated with wider age imbalances.

Data Sources

Phase 3 clinical oncology RCTs were identified through ClinicalTrials.gov.

Study Selection

Multiarm RCTs assessing a therapeutic intervention for patients with breast, prostate, colorectal, or lung cancer (the 4 most common cancer disease sites) were included.

Data Extraction and Synthesis

Trial data were extracted from ClinicalTrials.gov. Trial screening and parameter identification were independently performed by 2 individuals. Data were analyzed in 2018.

Main Outcomes and Measures

The difference in median age (DMA) between the trial participant median age and the population-based disease-site-specific median age was determined for each trial.

Results

Three hundred two trials met inclusion criteria. The trials collectively enrolled 262 354 participants; 249 trials (82.5%) were industry-funded. For all trials, the trial median age of trial participants was a mean of 6.49 years younger than the population median age (95% CI, -7.17 to -5.81 years; P < .001). Age disparities were heightened among industry-funded trials compared with non-industry-funded trials (mean DMA, -6.84 vs -4.72 years; P = .002). Enrollment criteria restrictions based on performance status or age cutoffs were associated with age disparities; however, industry-funded trials were not more likely to use these enrollment restrictions than non-industry-funded trials. Age disparities were also larger among trials that evaluated a targeted systemic therapy and among lung cancer trials. Linear regression modeling revealed a widening gap between trial and population median ages over time at a rate of -0.19 years annually (95% CI, -0.37 to -0.01 years; P = .04).

Conclusions and Relevance

Age disparities between trial participants and the incident disease population are pervasive across trials and appear to be increasing over time. Industry sponsorship of trials is associated with heightened age imbalances among trial participants. With an increasing role of industry funding among cancer trials, efforts to understand and address age disparities are necessary to ensure generalizability of trial results as well as equity in trial access.

National Quality Measure Compliance for Palliative Bone Radiation Among Patients With Metastatic Non-Small Cell Lung Cancer

BACKGROUND

There exists wide practice variability in palliative treatment schedules for bone metastases. In an effort to reduce variation and promote high-quality, cost-conscious care, the National Quality Forum (NQF) endorsed measure 1822 in 2012. This measure recommends the use of 30 Gy in 10 fractions, 24 Gy in 6 fractions, 20 Gy in 5 fractions, or 8 Gy in a single fraction for palliative radiation for bone metastases. We report on longitudinal compliance with this measure.

METHODS

Using the National Cancer Database, patients with metastatic thoracic non-small cell lung cancer diagnosed between 2004 and 2016 who received radiation therapy for bony sites of metastatic disease were identified. Treatment courses fitting 1 of the 4 recommended schedules under NQF 1822 were coded as compliant. Rates of compliance by patient, tumor, and treatment characteristics were analyzed.

RESULTS

A total of 42,685 patients met the criteria for inclusion. Among all patients, 60.2% of treatment courses were compliant according to NQF 1822. Compliance increased over time and was highest for treatments to the extremity (69.8%), lowest for treatments to the skull or head (48.8%), and higher for academic practice (67.1%) compared with community (56.0%) or integrated network facilities (61.2%). On multivariable analysis, predictors of NQF 1822 compliance included year of diagnosis after 2011, treatment to an extremity, or treatment at an academic facility. Of noncompliant treatment courses, extended fractionation (≥11 fractions) occurred in 62.6% and was more common before 2012, in community practice, and for treatments of the skull or head.

CONCLUSIONS

Among patients treated for metastatic non-small cell lung cancer, compliance with NQF 1822 increased over time. Although extended fractionation constituted a majority of noncompliant treatment courses, a substantial proportion also involved shorter courses.

Driver mutations to predict for poorer outcomes in non-small cell lung cancer patients treated with concurrent chemoradiation and consolidation durvalumab

8528

Background: The use of durvalumab after chemoradiation in locally advanced non-small cell lung cancer (NSCLC) patients significantly improves overall survival. However, it is unclear whether this benefit applies to all genetic subtypes of lung cancer. We hypothesize that patients with driver mutation NSCLC may derive less benefit from consolidation durvalumab. Methods: Using the Genomic Marker-Guided Therapy Initiative (GEMINI) database at MD Anderson, we identified 134 patients who were treated with chemoradiation followed by durvalumab for NSCLC. We segregated patients with driver mutations to targetable (EGFR, ALK translocation, ROS1 fusion, MET exon 14 skipping, RET fusion, and/or BRAF) (N = 24) and those driven by canonical KRAS mutations (N = 26). The rest (N = 84) had none of these mutations. We gathered demographic, treatment, and outcome data and compared progression-free survival (PFS) and overall survival (OS) using the Kaplan-Meier method. We used multivariate regression analysis to account for demographic and treatment variables. Results: For our cohort, median age at diagnosis was 64.8, 52% were female (n = 70), and median follow up was 1.5 years. 86% of patients have a history of smoking (n = 115). 21% had squamous cell histology (n = 28). 2 patients had stage IIA disease, 6 had stage IIB, 48 had stage IIIA, 56 had stage IIIB, 13 had stage IIIC, and 9 had stage IV. 73 patients had progression after durvalumab and 37 patients died. Patients with driver mutations had significantly worse median PFS compared to those without driver mutations (8.9 mo vs 26.6 mo; HR 2.62 p < 0.001). Patients with KRAS mutations had particularly poor PFS (Median 7.9 mo, HR 3.34, p < 0.001), while patients with targetable driver mutations trended to worse PFS (Median 14.5 mo, HR 1.96, p = 0.056). The median OS for the cohort was 4.8 yrs with no significant differences based on driver mutation status. On multivariate analysis, only driver mutation status was associated with PFS, but not OS. For patients with first progression, we found the targetable driver group to have significantly improved time to second objective progression (PFS2) compared to the KRAS (HR 0.28, p = 0.011) or non-mutated group (HR 0.38, p = 0.025). All patients in the targetable driver group received targeted therapy after first progression. Conclusions: Our results suggest that patients with driver mutations have worse PFS compared to patients without these mutations after chemoradiation. However, patients with targetable oncogene driver mutations have significantly improved prognosis after initial progression compared to the other groups, likely due to targeted therapy, suggesting that these therapies, including novel approaches towards KRAS mutants, should be further explored in this setting.

Hyper engorged cancer associated macrophage-like cells in circulation predict for multi-organ metastatic disease in solid tumors

3039

Background: Patients with multiple organ metastases have poorer prognoses than those with a single organ metastasis, are frequently associated with drug resistance, and have higher tumor burden. Engorged (≥50um) Cancer Associated Macrophage-Like Cells (CAMLs) are a circulating stromal cell subtype detected in the blood of patients with solid tumors at high risk for recurrence or progression. While numerous studies have shown that ≥50um CAMLs predict poor clinical outcomes, meta-analysis of these studies have also suggested that hyper engorged CAMLs ≥100um (heCAMLs) may be associated with multifocal metastatic disease and even worse outcomes. In this prospective study, we evaluated the presence of heCAMLs in patients with metastatic disease and demonstrated a strong relationship with multi organ spread, which also correlated with shorter Progression Free Survival (PFS) and Overall Survival (OS). Methods: We prospectively recruited 151 patients with metastatic (m) mbreast (n = 58), mlung (n = 34), mprostate (n = 39), and mrenal (n = 20) cancers. Peripheral blood was collected prior to the induction of new treatment for metastatic cancer. Cells were isolated following standard CellSieve techniques, then imaged and measured in ZenBlue. Multi organ metastasis was defined as spread to ≥2 distant organ sites, or any spread to the brain. Single factor ANOVA was conducted to compare heCAML presence in multi organ metastatic patients versus patients with single organ site metastasis. Univariate and multivariate analysis was run to evaluate for PFS and OS against heCAMLs, and all known clinical parameters. Results: 150 viable samples (excluding 1 failed sample) were obtained. Multi organ metastases were present in 55% (n = 83/150) of patients. heCAMLs were found in 59% (n = 49/83) of the multi organ metastatic population, but only in 16% (n = 11/67) of the single site metastatic cohort (p < 0.001). heCAML presence appeared to differentiate multi organ vs single organ metastases in mbreast (85% vs. 52%, p = 0.006), mlung (71% vs. 26%, p = 0.025), mprostate (75% vs. 37%, p = 0.029), and mRCC (88% vs. 36%, p = 0.025). Further, in all n = 150 patients, heCAML presence predicted a significantly shorter median PFS of 4.5 versus 7.2 months, 24 month PFS (HR = 1.67, 95%CI = 1.13-2.45, p = 0.013), and significantly shorter median OS of 13.1 versus 20.4 months, 24 month OS (HR = 2.05, 95%CI = 1.24-3.39, p = 0.008). Conclusions: We examined a non-invasive prognostic blood based assay to determine its relationship to multi organ metastatic spread as well as its prognostic value in several solid cancers. These results showed patients with heCAMLs had higher rates of multi organ metastases, and appear to predict for shorter PFS and OS. Studies of larger cohorts are needed for prospective validation of these initial findings.

Noninvasive identification of emergent mutations following cytotoxic therapy for lung cancer

8533

Background: Lung cancer is the leading cause of cancer death world-wide, and chemotherapy and radiation remain backbones of therapy for patients with locoregionally advanced and metastatic disease. However, the genetic mechanisms that mediate resistance to chemotherapy and radiation are largely unclear due to a lack of available tissue at the time of relapse. We hypothesized that circulating tumor DNA (ctDNA) analysis could identify emergent mutations after chemotherapy and radiation that may lead to treatment resistance. Methods: To identify emergent mutations at the time of progression following an initial response to chemotherapy and/or radiation therapy for lung cancer, we utilized CAncer Personalized Profiling by deep Sequencing (CAPP-Seq) to analyze plasma samples and matched leukocytes collected pre-treatment and at the time of relapse. We analyzed a targeted panel enriched for lung cancer drivers and recurrently mutated genes for 27 patients treated with chemoradiation therapy for locoregionally advanced lung cancer. In addition, we performed ultra-deep whole exome sequencing ( > 2000X deduped depth) of pre-treatment and relapse cell-free DNA for 5 patients treated with combination chemotherapy for metastatic lung cancer. Functional enrichment analysis was performed on emergent mutation gene lists to identify significantly enriched pathways. Results: We identified emergent variants in 6 out of 27 patients using targeted sequencing after chemoradiation therapy. Emergent mutations after chemoradiation were enriched for plasma membrane adhesion molecules such as PCDH17, PCDH10, and FAT3 (adjusted P = 0.03). Using ultra-deep whole exome sequencing, we observed emergent mutations in 3 out of 5 patients treated with combination chemotherapy. After combination chemotherapy, there was a trend towards enrichment in mutations in ATP-binding cassette transporters, including ABCA13 and ABCB4 (adjusted P = 0.057). Notably, there were no recurrent emergent mutations within our cohort. Conclusions: Our results suggest that ultra-deep whole exome sequencing can non-invasively identify emergent mutations at the time of progression. Resistance to cytotoxic therapy is likely multi-factorial and analysis in expanded cohorts will be helpful to identify recurrently mutated pathways that may contribute to disease progression after an initial response to therapy.

Sequential monitoring of PD-L1 on circulating stromal cells in blood predicts PFS in NSCLC patients undergoing immunotherapy after definitive chemoradiation

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Background: Cancer Associated Macrophage-Like cells (CAMLs) are circulating stromal cells in the blood of patients (pts) with solid tumors that are phagocytic macrophages that may represent the inflammatory state of the tumor microenvironment. Previously, we demonstrated CAMLs ≥50µm after chemo-radiation therapy (CRT) in NSCLC is associated with worse progression free survival (PFS) and overall survival (OS). We also showed that PDL1 expression in CAMLs is dynamic & can change with CRT, difficult to assess with repeat biopsies, but possible with liquid biopsy. For this study we evaluated whether CAML properties can predict response to CRT with/without immunotherapy (IMT) agents in unresectable NSCLC. Methods: A single blind multi-year prospective study was undertaken to test the relationship of PDL1 expression and ≥50µm CAML size to PFS/OS in NSCLC, pre and post CRT with (n = 96) and without (n = 72) anti-PDL1/PD1 IMT. This included atezolizumab (prospective single arm NCT02525757) n = 39, durvalumab n = 52 or pembrolizumab n = 5 both after 2018 FDA approval. We recruited 168 pts with pathologically confirmed unresectable NSCLC prior to CRT. Blood samples 15 mL were taken at baseline (BL), CRT completion (T1), and ̃1 month after CRT (T2) (with n = 96 or without n = 72 IMT). Blood was filtered by CellSieve filtration and CAMLs quantified for size ( < 49 µm or ≥50 µm) and PDL1 expression to evaluate PFS and OS hazard ratios (HRs) by censored univariate and multivariate analysis at 24 months. Results: CAMLs were found in 90% of all samples, average 5.8 CAMLs/15mL. At BL, ≥50µm CAMLs did not predict PFS in CRT/IMT pts (HR 1.6, p = 0.220) nor CRT alone (HR 1.3, p = 0.593). However, after completion of CRT (T1) ≥50µm CAMLs predicted PFS in CRT/IMT pts (HR 2.7, p = 0.003) and CRT alone (HR 2.5, p = 0.015). In primary tumor biopsies, PDL1 expression > 1% did not predict CRT/IMT response (PFS HR 1.8, p = 0.262 & OS HR 2.3, p = 0.158). At BL, high CAML PDL1 did not predict PFS in CRT/IMT pts (HR 1.4, p = 0.427) nor CRT alone (HR 1.1, p = 0.982). Further, at CRT completion (T1), high CAML PDL1 only trended for better PFS in CRT/IMT pts (HR 1.7, p = 0.137), but not CRT alone (HR 1.1, p = 0.972). At T2, however, pts with continuously high CAML PDL1 had significantly better PFS with IMT (HR 3.2, p = 0.002) vs CRT alone (HR 1.4, p = 0.616). While ≥50µm CAMLs at BL did not predict 24 month progression, ≥50 µm CAMLs after CRT (with or without 1 cycle of anti-PDL1 IMT) was 84% accurate at predicting progression. Further subtyping and analysis is ongoing to evaluate OS and PDL1 in the CAML populations. Conclusions: Our data suggests that in unresectable NSCLC, ≥50 µm CAMLs after completion of CRT is prognostic regardless of IMT use. PDL1 expression in CAMLs also appears to predict for response to consolidated IMT after CRT. Additional studies are needed to validate these findings.

A phase II/III study of perioperative nivolumab and ipilimumab in patients (pts) with locoregional esophageal (E) and gastroesophageal junction (GEJ) adenocarcinoma: Results of a safety run-in—A trial of the ECOG-ACRIN Cancer Research Group (EA2174)

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Background: E/GEJ adenocarcinoma has a high mortality rate despite curative intent therapy. The use of immune checkpoint inhibition is beneficial for treatment of this cancer in the metastatic and adjuvant settings but the role of these agents in the perioperative setting remains unclear. Here we report the results of an initial safety run-in of nivolumab when given in combination with neoadjuvant chemoradiation. Methods: Pts with a localized T1N1-3M0 or T2-3N0-2M0 E/GEJ adenocarcinoma with an ECOG PS of 0-1 and whom were deemed surgical candidates for an esophagectomy by a qualified surgeon were eligible. In step 1, pts were randomized to neoadjuvant therapy with carboplatin AUC 2 and paclitaxel 50 mg/m2 intravenously (IV) weekly x 5 along with 41.4-50.4 Gy radiation without (Arm A) or with (Arm B) nivolumab 240 mg IV during weeks 1 and 3 of treatment, followed by esophagectomy. Pts underwent a second randomization (step 2) to adjuvant nivolumab 240 mg IV every 2 weeks x 12 cycles with or without ipilimumab 1 mg/kg IV every 6 weeks during cycles 1, 4, 7 and 10. For the safety run-in, 30 pts were planned for accrual to allow for 12 evaluable pts per arm. Pts were followed for safety during neoadjuvant therapy through surgery and toxicities monitored per CTCAEv5. Pre-specified early stopping rules were defined to allow halting of the trial if deemed unsafe. Planned study accrual is 278 pts. Neoadjuvant primary endpoint is pathologic complete response rate, adjuvant primary endpoint is disease-free survival. Results: A total of 31 pts were enrolled to the safety run-in element of the study (Arm A, n = 16; Arm B n = 15). Male, 94%; White, 100%; median age, 62; esophageal adenocarcinoma, 52%; GEJ, 48%. Grade (G) 3 events occurring in more than one pt on Arm A—decreased lymphocytes (n = 5). G4 events occurring on Arm A—decreased lymphocytes (n = 1). G3 events occurring in more than one pt on Arm B—decreased lymphocytes (n = 2); anemia (n = 2); leukopenia (n = 4); hypotension (n = 2). G4 events occurring on Arm B—decreased lymphocytes (n = 3); cardiac tamponade and pericardial effusion (n = 1). Cardiac events were thought to be secondary to tumor location, not neoadjuvant treatment. On Arm B, notable G3 events seen in one pt each included colonic obstruction, wound infection and esophageal anastomotic leak. Of pts who have reached the time for surgery, 12/14 pts on Arm A and 13/13 pts on Arm B have proceeded to surgery. Of pts who have completed step 1, 7/14 pts on Arm A and 8/11 pts on Arm B have registered to step 2. Conclusions: The addition of nivolumab to carboplatin, paclitaxel and radiation in the neoadjuvant setting appears to be safe with no disproportionate level of toxicity observed between the two treatment arms. Accrual to the remainder of the trial continues with 43/278 patients accrued. Clinical trial information: NCT03604991.

Cell lines of the same anatomic site and histologic type show large variability in intrinsic radiosensitivity and relative biological effectiveness to protons and carbon ions

PURPOSE

To show that intrinsic radiosensitivity varies greatly for protons and carbon (C) ions in addition to photons, and that DNA repair capacity remains important in governing this variability.

METHODS

We measured or obtained from the literature clonogenic survival data for a number of human cancer cell lines exposed to photons, protons (9.9 keV/μm), and C-ions (13.3-77.1 keV/μm). We characterized their intrinsic radiosensitivity by the dose for 10% or 50% survival (D_10% or D_50% ), and quantified the variability at each radiation quality by the coefficient of variation (COV) in D_10% and D_50% . We also treated cells with DNA repair inhibitors prior to irradiation to assess how DNA repair capacity affects their variability.

RESULTS

We found no statistically significant differences in the COVs of D_10% or D_50% between any of the radiation qualities investigated. The same was true regardless of whether the cells were treated with DNA repair inhibitors, or whether they were stratified into histologic subsets. Even within histologic subsets, we found remarkable differences in radiosensitivity for high LET C-ions that were often greater than the variations in RBE, with brain cancer cells varying in D_10% (D_50% ) up to 100% (131%) for 77.1 keV/μm C-ions, and non-small cell lung cancer and pancreatic cancer cell lines varying up to 55% (76%) and 51% (78%), respectively, for 60.5 keV/μm C-ions. The cell lines with modulated DNA repair capacity had greater variability in intrinsic radiosensitivity across all radiation qualities.

CONCLUSIONS

Even for cell lines of the same histologic type, there are remarkable variations in intrinsic radiosensitivity, and these variations do not differ significantly between photon, proton or C-ion radiation. The importance of DNA repair capacity in governing the variability in intrinsic radiosensitivity is not significantly diminished for higher LET radiation.

Giant Circulating Cancer-Associated Macrophage-Like Cells Are Associated With Disease Recurrence and Survival in Non-Small-Cell Lung Cancer Treated With Chemoradiation and Atezolizumab

BACKGROUND

Cancer-associated macrophage-like cells (CAMLs) are a potential peripheral blood biomarker for disease progression. This study used data from a phase 2 clinical trial to evaluate prognostic utility of CAMLs for locally advanced non-small-cell lung cancer treated with definitive chemoradiotherapy (CRT) and atezolizumab (DETERRED; ClinicalTrials.gov NCT02525757).

PATIENTS AND METHODS

Sample collection occurred at baseline (T0), during CRT (T1), at end of CRT (T2), and at first follow-up (T3). CAMLs were captured and quantified by the CellSieve system using multiplex immunostaining. Giant CAMLs were defined as characteristic CAMLs ≥ 50 μm. Kaplan-Meier methodology estimated progression-free survival, distant failure-free survival, relapse-free survival, and overall survival at 30 months.

RESULTS

Thirty-nine patients were evaluated between December 2015 and March 2018. Median follow-up was 27 months. Most disease was stage III (85%) and comprised squamous-cell carcinoma (38%) or adenocarcinoma (59%). In total, 267 blood samples were analyzed. Giant CAMLs were identified in 57%, 60%, 64%, and 63% of patients at T0, T1, T2, and T3, respectively. Patients with giant CAMLs at T3, occurring at a median of 30 days after completion of CRT, had significantly worse distant failure-free survival (hazard ratio [HR] 4.9, P = .015), progression-free survival (HR 2.5, P = .025), recurrence-free survival (HR 2.4, P = .036), and overall survival (HR 3.5, P = .034) compared to patients with small or no CAMLs.

CONCLUSIONS

Presence of giant CAMLs after CRT completion was associated with development of metastatic disease and poorer survival despite the use of maintenance immunotherapy. Monitoring CAMLs may help risk-stratify patients for adaptive treatment strategies.

Postoperative Radiotherapy for Locally Advanced NSCLC: Implications for Shifting to Conformal, High-Risk Fields

BACKGROUND

To examine the effect of radiotherapy field size on survival outcomes and patterns of recurrence in patients treated with postoperative radiotherapy (PORT) for non-small-cell lung cancer (NSCLC).

METHODS

We retrospectively reviewed the records of 216 patients with T1-4 N1-2 NSCLC following surgery and PORT using whole mediastinum (WM) or high-risk (HR) nodal fields from 1998 to 2015. Survival rates were calculated using the Kaplan-Meier method. Univariate and multivariable analyses were conducted using Cox proportional hazards modeling for outcomes and logistic regression analysis for treatment toxicities.

RESULTS

Median follow-up was 28 months (interquartile range [IQR] 13-75 months) and 38 months (IQR 19-73 months) for WM (n = 131) and HR (n = 84) groups, respectively. Overall survival (OS) was not significantly different between groups (median OS: HR 49 vs. WM 32 months; P = .08). There was no difference in progression-free survival (PFS), freedom from locoregional recurrence (LRR), or freedom from distant metastasis (P > .2 for all). Field size was not associated with OS, PFS, or LRR (P > .40 for all). LRR rates were 20% for HR and 26% for WM groups (P = .30). There was no significant difference in patterns of initial site of LRR between groups (P > .1). WM fields (OR 3.73, P = .001) and concurrent chemotherapy (odds ratio 3.62, P = .001) were associated with grade ≥2 toxicity.

CONCLUSIONS

Locoregional control and survival rates were similar between PORT groups; an improved toxicity profile was observed in the HR group. Results from an ongoing prospective randomized clinical trial will provide further insight into the consequences of HR PORT fields.

Abstract PO-069: Circulating tumor DNA kinetics to identify genomic predictors of rapid response to chemoradiation in non-small cell lung cancer

Introduction: Despite evidence that a subset of patients with locoregionally advanced non-small cell lung cancer (NSCLC) can be cured with radiation doses less than 60 Gy, there are currently no validated approaches to identify patients that could benefit from radiation dose de-escalation. Normal tissue changes including inflammation and fibrosis can be difficult to distinguish from residual disease on standard imaging during and following chemoradiation therapy (CRT), making assessment of treatment response and identification of favorable responders challenging. We hypothesized that circulating tumor DNA (ctDNA) kinetics during CRT could be used as a surrogate of response to identify genomic predictors of rapid response to treatment. Methods: We applied cancer personalized profiling by deep sequencing (CAPP-Seq) ctDNA analysis to 61 patients treated with CRT for Stage II-III NSCLC. We quantified ctDNA concentrations pre-CRT and a median of 21 days into CRT (mid-CRT) to determine the log-fold change in ctDNA concentration and identify “rapid responders.” The association between ctDNA log-fold change as a continuous variable with progression-free survival (PFS) was analyzed using univariable and multivariable regression, including gender, age, and stage as co-variables. The prevalence of driver gene single nucleotide variants in rapid responders versus slow responders was compared for each gene using Fisher’s exact tests with P-values adjusted using the Benjamini-Hochberg procedure. Results: Mid-CRT ctDNA log-fold change was significantly associated with progression-free survival as a continuous variable on both univariable (P=0.02) and multivariable analysis (P=0.03). Among patients whose ctDNA log-fold change was more negative than -2.15, 10/11 (91%) did not recur within the radiation field. We defined ctDNA rapid responders as the 10 patients with the largest decrease in ctDNA concentration mid-CRT without local progression. Compared with slow responders, ctDNA rapid responders had a trend towards more TP53 mutations (P=0.12), but no driver mutations were significantly enriched in rapid responders. Notably, mutations in common driver genes KEAP1, NFE2L2, KRAS, and EGFR were observed in 36% of slow responders and 0% of rapid responders (P=0.03). Conclusions: Our results suggest that ctDNA kinetics during CRT can identify patients responding favorably to treatment. Additional molecular characterization of ctDNA rapid responders may enable identification of patients who could benefit from treatment de-escalation.

Citation Format: Everett J. Moding, Yufei Liu, Angela B. Hui, Jianzhong He, Yawei Qiao, Ting Xu, Luyang Yao, Saumil Gandhi, Zhongxing Liao, Millie Das, Kavitha J. Ramchandran, Sukhmani K. Padda, Joel W. Neal, Heather A. Wakelee, Billy W. Loo, Steven H. Lin, Ash A. Alizadeh, Maximilian Diehn. Circulating tumor DNA kinetics to identify genomic predictors of rapid response to chemoradiation in non-small cell lung cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-069.

Association Between Sex and Immune-Related Adverse Events During Immune Checkpoint Inhibitor Therapy

BACKGROUND

Accumulated evidence supports the existence of sex-associated differences in immune systems. Understanding the role of sex in immune-related adverse events (irAEs) is important for management of irAE in patients receiving immunotherapy.

METHODS

We performed meta-analysis on published clinical study data and multivariable logistic regression on pharmacovigilance data and applied a propensity algorithm to The Cancer Genome Atlas (TCGA) omics data. We further validated our observations in two independent in-house cohorts of 179 and 767 cancer patients treated with immune checkpoint inhibitors.

RESULTS

A meta-analysis using 13 clinical studies that reported on 1,096 female patients (36.8%, 95% confidence interval [CI] = 35.0%-38.5%) and 1,886 male patients (63.2%, 95% CI = 61.5%-65.0%) demonstrated no statistically significant irAE risk difference between the sexes (odds ratio [OR] = 1.19; 95% CI = 0.91-1.54; 2-sided P = 0.21). Multivariable logistic regression analysis of 12,225 patients from FAERS and 10,979 patients from VigiBase showed no statistically significant difference in irAEs by sex. A propensity score algorithm used on multi-omics data for 6,019 patients from TCGA found no statistically significant difference by sex for irAE-related factors/pathways. The retrospective analysis of two in-house patient cohorts validated these results (OR = 1.55, 95% CI = 0.98-2.47; FDR = 0.13, for cohort 1; OR = 1.16, 95%CI = 0.86-1.57; FDR = 0.39, for cohort 2).

CONCLUSION

We observed minimal sex-associated differences in irAEs among cancer patients who received immune checkpoint inhibitor therapy. It may be unnecessary to consider gender effects for irAE management in clinical practice.