Radiation-Associated Lymphopenia and Outcomes of Patients with Unresectable Hepatocellular Carcinoma Treated with Radiotherapy

Background

The immune system plays a crucial role in cancer surveillance. Previous studies have shown that lymphopenia associated with radiotherapy (RT) portends a poor prognosis. We sought to differentiate the effects of proton and photon RT on changes in absolute lymphocyte count (ALC) for patients with hepatocellular carcinoma (HCC).

Patients and Methods

Patients with HCC treated with definitive RT from 2006 to 2016 were studied. Serial ALCs were graded according to CTCAE v4.0. Overall survival (OS), disease-free survival, and distant metastasis-free survival were analyzed using the Kaplan-Meier method. Univariable and multivariable Cox-proportional hazards analyses were used to identify predictors of OS. A cohort analysis matched for treatment volume was performed to investigate differences in ALC dynamics between photon and proton therapy.

Results

Of 143 patients identified, the median age was 66 (range, 19-90) years. The treatment modality was photon in 103 (72%) and proton in 40 (28%). Median follow-up was 17 months (95% confidence interval, 13-25 months). The median time to ALC nadir after initiation of RT was 17 days with a median relative decrease of 67%. Those who received proton RT had a higher median ALC nadir (0.41 vs 0.32 k/µL, p=0.002) and longer median OS (33 vs 13 months, p=0.002) than those who received photon RT. Matched cohort analyses revealed a larger low-dose liver volume in the photon group, which correlated with lower ALC. On multivariable Cox analysis, Grade 3 or higher lymphopenia prior to or after RT, portal venous tumor thrombus, larger planning target volumes, Child-Pugh (CP) Class B, and increased CP score after RT were associated with a higher risk of death, whereas the use of proton therapy was associated with lower risk.

Conclusion

Grade 3 or higher lymphopenia may be associated with poorer outcomes in patients receiving RT for HCC. Protons may mitigate lymphopenia compared with photons, potentially due to reduced dose exposure of sites of lymphopoiesis.

Proton therapy reduces the likelihood of high-grade radiation-induced lymphopenia in glioblastoma patients: phase II randomized study of protons vs photons

BACKGROUND

We investigated differences in radiation-induced grade 3+ lymphopenia (G3+L), defined as an absolute lymphocyte count (ALC) nadir of <500 cells/µL, after proton therapy (PT) or X-ray (photon) therapy (XRT) for patients with glioblastoma (GBM).

METHODS

Patients enrolled in a randomized phase II trial received PT (n = 28) or XRT (n = 56) concomitantly with temozolomide. ALC was measured before, weekly during, and within 1 month after radiotherapy. Whole-brain mean dose (WBMD) and brain dose-volume indices were extracted from planned dose distributions. Univariate and multivariate logistic regression analyses were used to identify independent predictive variables. The resulting model was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Rates of G3+L were lower in men (7/47 [15%]) versus women (19/37 [51%]) (P < 0.001), and for PT (4/28 [14%]) versus XRT (22/56 [39%]) (P = 0.024). G3+L was significantly associated with baseline ALC, WBMD, and brain volumes receiving 5‒40 Gy(relative biological effectiveness [RBE]) or higher (ie, V5 through V40). Stepwise multivariate logistic regression analysis identified being female (odds ratio [OR] 6.2, 95% confidence interval [CI]: 1.95‒22.4, P = 0.003), baseline ALC (OR 0.18, 95% CI: 0.05‒0.51, P = 0.003), and whole-brain V20 (OR 1.07, 95% CI: 1.03‒1.13, P = 0.002) as the strongest predictors. ROC analysis yielded an area under the curve of 0.86 (95% CI: 0.79-0.94) for the final G3+L prediction model.

CONCLUSIONS

Sex, baseline ALC, and whole-brain V20 were the strongest predictors of G3+L for patients with GBM treated with radiation and temozolomide. PT reduced brain volumes receiving low and intermediate doses and, consequently, reduced G3+L.

Single Institution Experience of Proton and Photon-based Postoperative Radiation Therapy for Non-small-cell Lung Cancer

INTRODUCTION

Postoperative radiation therapy (PORT) for non-small-cell lung cancer remains controversial with studies showing no overall survival (OS) benefit in the setting of excessive cardiopulmonary toxicity. Proton beam therapy (PBT) can potentially reduce toxicity with improved organ-at-risk sparing. We evaluated outcomes of PORT patients treated with PBT and intensity-modulated radiation therapy (IMRT).

MATERIALS AND METHODS

This is a retrospective review of 136 PORT patients (61 PBT, 75 IMRT) treated from 2003 to 2016. A Kaplan-Meier analysis was performed to assess oncologic outcomes. A Cox regression was conducted to identify associated factors. Total toxicity burden (TTB) was defined as grade ≥ 2 pneumonitis, cardiac, or esophageal toxicity.

RESULTS

Median OS was 76 and 46 months for PBT and IMRT with corresponding 1- and 5-year OS of 85.3%, 50.9% and 89.3%, 37.2% (P = .38), respectively. V30 Gy heart (odds ratio [OR], 144.9; 95% confidence interval [CI], 2.91-7214; P = .013) and V5 Gy lung (OR, 15.8; 95% CI, 1.22-202.7; P = .03) were predictive of OS. Organ-at-risk sparing was improved with PBT versus IMRT; mean heart 2.0 versus 7.4 Gy (P < .01), V30 Gy heart 2.6% versus 10.7% (P < .01), mean lung 7.9 versus 10.4 Gy (P = .042), V5 Gy lung 23.4% versus 42.1% (P < .01), and V10 Gy lung 20.4% versus 29.6% (P < .01). TTB was reduced with PBT (OR, 0.35; 95% CI, 0.15-0.83; P = .017). Rates of cardiac toxicity were 14.7% IMRT and 4.9% PBT (P = .09). Rates of ≥ grade 2 pneumonitis were 17.0% IMRT and 4.9% PBT (P = .104).

CONCLUSION

PBT improved cardiac and lung sparing and reduced toxicity compared with IMRT. Considering the impact of cardiopulmonary toxicity on PORT outcomes, PBT warrants prospective evaluation.

Toxicity and Survival After Intensity-Modulated Proton Therapy Versus Passive Scattering Proton Therapy for NSCLC

OBJECTIVE

Although intensity-modulated radiation therapy (IMPT) is dosimetrically superior to passive scattering proton therapy (PSPT) for locally advanced NSCLC (LA-NSCLC), direct comparisons of clinical outcomes are lacking. Here, we compare toxicity profiles and clinical outcomes after IMPT versus PSPT for LA-NSCLC.

METHODS

This is a nonrandomized, comparative study of two independent cohorts with LA-NSCLC (stage II-IIIB, stage IV with solitary brain metastasis) treated with concurrent chemotherapy and proton beam therapy. Toxicity (Common Terminology Criteria for Adverse Events version 4.0) and outcomes were prospectively collected as part of a clinical trial (ClinicalTrials.gov identifier NCT00915005) or prospective registry (ClinicalTrials.gov identifier NCT00991094).

RESULTS

Of 139 patients, 86 (62%) received PSPT and 53 (38%) IMPT; median follow-up times were 23.9 and 29.0 months, respectively. IMPT delivered lower mean radiation doses to the lungs (PSPT 16.0 Gy versus IMPT 13.0 Gy, p < 0.001), heart (10.7 Gy versus 6.6 Gy, p = 0.004), and esophagus (27.4 Gy versus 21.8 Gy, p = 0.005). Consequently, the IMPT cohort had lower rates of grade 3 or higher pulmonary (17% versus 2%, p = 0.005) and cardiac (11% versus 0%, p = 0.01) toxicities. Six patients (7%) with PSPT and zero patients (0%) with IMPT experienced grade 4 or 5 toxicity. Lower rates of pulmonary (28% versus 3%, p = 0.006) and cardiac (14% versus 0%, p = 0.05) toxicities were observed in the IMPT cohort even after propensity score matching for baseline imbalances. There was also a trend toward longer median overall survival in the IMPT group (23.9 mo versus 36.2 mo, p = 0.09). No difference was found in the 3-year rates of local (25% versus 20%, p = 0.44), local-regional (29% versus 36%, p = 0.56) and distant (52% versus 51%, p = 0.71) recurrences.

CONCLUSIONS

IMPT is associated with lower radiation doses to the lung, heart, and esophagus, and lower rates of grade 3 or higher cardiopulmonary toxicity; additional clinical studies will be needed to assess the potential differences in survival between the two techniques.

Plasmonic nano-aperture label-free imaging (PANORAMA)

Label-free optical imaging of nanoscale objects faces fundamental challenges. Techniques based on propagating surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) have shown promises. However, challenges remain to achieve diffraction-limited resolution and better surface localization in SPR imaging. LSPR imaging with dark-field microscopy on metallic nanostructures suffers from low light throughput and insufficient imaging capacity. Here we show ultra-near-field index modulated PlAsmonic NanO-apeRture lAbel-free iMAging (PANORAMA) which uniquely relies on unscattered light to detect sub-100 nm dielectric nanoparticles. PANORAMA provides diffraction-limited resolution, higher surface sensitivity, and wide-field imaging with dense spatial sampling. Its system is identical to a standard bright-field microscope with a lamp and a camera – no laser or interferometry is needed. In a parallel fashion, PANORAMA can detect, count and size individual dielectric nanoparticles beyond 25 nm, and dynamically monitor their distance to the plasmonic surface at millisecond timescale.

Here, the authors report on an imaging method based on localized surface plasmon resonance excitation, employing gold nanodisk arrays as substrates that enable imaging of transparent dielectric particles of several sizes. They demonstrate the ability to detect and image particles smaller than the diffraction limit at 25 nm with standard bright-field imaging.

p90RSK-MAGI1 Module Controls Endothelial Permeability by Post-translational Modifications of MAGI1 and Hippo Pathway

Previously, we reported that post-translational modifications (PTMs) of MAGI1, including S741 phosphorylation and K931 de-SUMOylation, both of which are regulated by p90RSK activation, lead to endothelial cell (EC) activation. However, roles for p90RSK and MAGI1-PTMs in regulating EC permeability remain unclear despite MAGI1 being a junctional molecule. Here, we show that thrombin (Thb)-induced EC permeability, detected by the electric cell-substrate impedance sensing (ECIS) based system, was decreased by overexpression of dominant negative p90RSK or a MAGI1-S741A phosphorylation mutant, but was accelerated by overexpression of p90RSK, siRNA-mediated knockdown of magi1, or the MAGI1-K931R SUMOylation mutant. MAGI1 depletion also increased the mRNA and protein expression of the large tumor suppressor kinases 1 and 2 (LATS1/2), which inhibited YAP/TAZ activity and increased EC permeability. Because the endothelial barrier is a critical mediator of tumor hypoxia, we also evaluated the role of p90RSK activation in tumor vessel leakiness by using a relatively low dose of the p90RSK specific inhibitor, FMK-MEA. FMK-MEA significantly inhibited tumor vessel leakiness at a dose that does not affect morphology and growth of tumor vessels in vivo. These results provide novel insights into crucial roles for p90RSK-mediated MAGI1 PTMs and the Hippo pathway in EC permeability, as well as p90RSK activation in tumor vessel leakiness.

Cancer associated macrophage-like cells and prognosis of esophageal cancer after chemoradiation therapy

BACKGROUND

Cancer Associated Macrophage-Like cells (CAMLs) are polynucleated circulating stromal cells found in the bloodstream of numerous solid-tumor malignancies. Variations within CAML size have been associated with poorer progression free survival (PFS) and overall survival (OS) in a variety of cancers; however, no study has evaluated their clinical significance in esophageal cancer (EC).

METHODS

To examine this significance, we ran a 2 year prospective pilot study consisting of newly diagnosed stage I-III EC patients (n = 32) receiving chemoradiotherapy (CRT). CAML sizes were sequentially monitored prior to CRT (BL), ~ 2 weeks into treatment (T1), and at the first available sample after the completion of CRT (T2).

RESULTS

We found CAMLs in 88% (n = 28/32) of all patient samples throughout the trial, with a sensitivity of 76% (n = 22/29) in pre-treatment screening samples. Improved 2 year PFS and OS was found in patients with CAMLs < 50 μm by the completion of CRT over patients with CAMLs ≥ 50 μm; PFS (HR = 12.0, 95% CI = 2.7-54.1, p = 0.004) and OS (HR = 9.0, 95%CI = 1.9-43.5, p = 0.019).

CONCLUSIONS

Tracking CAML sizes throughout CRT as a minimally invasive biomarker may serve as a prognostic tool in mapping EC progression, and further studies are warranted to determine if presence of these cells prior to treatment suggest diagnostic value for at-risk populations.

Multi-institutional Evaluation of Curative Intent Chemoradiotherapy for Patients With Clinical T1N0 Esophageal Adenocarcinoma

Purpose

To evaluate the safety and efficacy of definitive chemoradiotherapy (CRT) for patients with clinical T1N0M0 esophageal adenocarcinoma.

Methods and Materials

This was a retrospective study of patients with clinical T1N0 adenocarcinoma of the esophagus treated with curative-intent CRT between 2004 and 2017 at 2 tertiary care centers. Patients received CRT instead of esophagectomy owing to medical comorbidities or patient preference. Toxicities were evaluated according to Common Terminology Criteria for Adverse Events version 4.03. The Kaplan-Meier method was used to estimate overall, progression-free, and disease-specific survivals.

Results

Twenty-eight patients were included for analysis. Median age was 76 years (range 55-90). The majority of patients were male (93%) and had a history of Barrett’s esophagus (71%). Tumor characteristics included distal esophagus location (93%), clinical stage T1b (86%), and median length of 2 cm (range, 1-9). Prior endoscopic resection was performed in 57%.

The median follow-up was 44 months (range, 4-146). The acute grade 3 adverse events were observed in 7 patients (25%). One patient died of complications potentially related to chemoradiation. Eight patients (29%) had disease progression at a median of 7.6 months after CRT. First site of progression was local only (14%), local and regional (11%), or distant (4%). Salvage locally directed treatment was performed in 3 of 4 patients with local-only recurrence. The 3-year overall survival, progression-free, and disease-specific rates were 78%, 62%, and 81%, respectively.

Conclusion

CRT is a safe and effective curative treatment strategy for select patients with clinical T1N0M0 esophageal adenocarcinoma.

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

BACKGROUND

Radiotherapy might augment systemic antitumoral responses to immunotherapy. In the PEMBRO-RT (phase 2) and MDACC (phase 1/2) trials, patients with metastatic non-small-cell lung cancer were randomly allocated immunotherapy (pembrolizumab) with or without radiotherapy. When the trials were analysed individually, a potential benefit was noted in the combination treatment arm. However, owing to the small sample size of each trial, differences in response rates and outcomes were not statistically significant but remained clinically notable. We therefore did a pooled analysis to infer whether radiotherapy improves responses to immunotherapy in patients with metastatic non-small-cell lung cancer.

METHODS

Inclusion criteria for the PEMBRO-RT and MDACC trials were patients (aged ≥18 years) with metastatic non-small-cell lung cancer and at least one unirradiated lesion to monitor for out-of-field response. In the PEMBRO-RT trial, patients had previously received chemotherapy, whereas in the MDACC trial, patients could be either previously treated or newly diagnosed. Patients in both trials were immunotherapy-naive. In the PEMBRO-RT trial, patients were randomly assigned (1:1) and stratified by smoking status (<10 vs ≥10 pack-years). In the MDACC trial, patients were entered into one of two cohorts based on radiotherapy schedule feasibility and randomly assigned (1:1). Because of the nature of the intervention in the combination treatment arm, blinding to radiotherapy was not feasible in either trial. Pembrolizumab was administered intravenously (200 mg every 3 weeks) with or without radiotherapy in both trials. In the PEMBRO-RT trial, the first dose of pembrolizumab was given sequentially less than 1 week after the last dose of radiotherapy (24 Gy in three fractions), whereas in the MDACC trial, pembrolizumab was given concurrently with the first dose of radiotherapy (50 Gy in four fractions or 45 Gy in 15 fractions). Only unirradiated lesions were measured for response. The endpoints for this pooled analysis were best out-of-field (abscopal) response rate (ARR), best abscopal disease control rate (ACR), ARR at 12 weeks, ACR at 12 weeks, progression-free survival, and overall survival. The intention-to-treat populations from both trials were included in analyses. The PEMBRO-RT trial (NCT02492568) and the MDACC trial (NCT02444741) are registered with ClinicalTrials.gov.

FINDINGS

Overall, 148 patients were included in the pooled analysis, 76 of whom had been assigned pembrolizumab and 72 who had been assigned pembrolizumab plus radiotherapy. Median follow-up for all patients was 33 months (IQR 32·4-33·6). 124 (84%) of 148 patients had non-squamous histological features and 111 (75%) had previously received chemotherapy. Baseline variables did not differ between treatment groups, including PD-L1 status and metastatic disease volume. The most frequently irradiated sites were lung metastases (28 of 72 [39%]), intrathoracic lymph nodes (15 of 72 [21%]), and lung primary disease (12 of 72 [17%]). Best ARR was 19·7% (15 of 76) with pembrolizumab versus 41·7% (30 of 72) with pembrolizumab plus radiotherapy (odds ratio [OR] 2·96, 95% CI 1·42-6·20; p=0·0039), and best ACR was 43·4% (33 of 76) with pembrolizumab versus 65·3% (47 of 72) with pembrolizumab plus radiotherapy (2·51, 1·28-4·91; p=0·0071). Median progression-free survival was 4·4 months (IQR 2·9-5·9) with pembrolizumab alone versus 9·0 months (6·8-11·2) with pembrolizumab plus radiotherapy (hazard ratio [HR] 0·67, 95% CI 0·45-0·99; p=0·045), and median overall survival was 8·7 months (6·4-11·0) with pembrolizumab versus 19·2 months (14·6-23·8) with pembrolizumab plus radiotherapy (0·67, 0·54-0·84; p=0·0004). No new safety concerns were noted in the pooled analysis.

INTERPRETATION

Adding radiotherapy to pembrolizumab immunotherapy significantly increased responses and outcomes in patients with metastatic non-small-cell lung cancer. These results warrant validation in a randomised phase 3 trial.

FUNDING

Merck Sharp & Dohme.

Modern Radiotherapy and Risk of Cardiotoxicity

Despite the advancements of modern radiotherapy, radiation-induced heart disease remains a common cause of morbidity and mortality amongst cancer survivors. This review outlines the basic mechanism, clinical presentation, risk stratification, early detection, possible mitigation, and treatment of this condition.

Pembrolizumab with or without radiation therapy for metastatic non-small cell lung cancer: a randomized phase I/II trial

Background

In this phase I/II trial, we evaluated the safety and effectiveness of pembrolizumab, with or without concurrent radiotherapy (RT), for lung and liver lesions from metastatic non-small cell lung cancer (mNSCLC).

Methods

Patients with lung or liver lesions amenable to RT plus at least one additional non-contiguous lesion were included regardless of programmed death-ligand 1 (PD-L1) status. Pembrolizumab was given at 200 mg every 3 weeks for up to 32 cycles with or without concurrent RT. Metastatic lesions were treated with stereotactic body RT (SBRT; 50 Gy in 4 fractions) if clinically feasible or with traditionally fractionated RT (45 Gy in 15 fractions) if not. The primary end point was the best out-of-field lesion response, and a key secondary end point was progression-free survival (PFS).

Results

The median follow-up time was 20.4 months. One hundred patients (20 phase I, 80 phase II) were evaluable for toxicity, and 72 phase II patients were evaluable for treatment response. No patients in the phase I group experienced grade 4–5 events; in the phase II group, two had grade 4 events and nine had grade 3 events. The ORR in the combined-modality cohort (irrespective of RT schema) was 22%, vs 25% in the pembrolizumab group (irrespective of receipt of salvage RT) (p=0.99). In the concurrent pembrolizumab+RT groups, the out-of-field ORRs were 38% in the pembrolizumab+SBRT group and 10% in the pembrolizumab+traditional RT group. When examining the pembrolizumab-alone patients, the out-of-field ORRs were 33% in those designated to receive salvage SBRT (if required) and 17% for salvage traditional RT. In all patients, the median PFS for pembrolizumab alone was 5.1 months (95% CI 3.4 to 12.7 months), and pembrolizumab/RT (regardless of schema) was 9.1 months (95% CI 3.6 to 18.4 months) (p=0.52). An exploratory analysis revealed that for patients with low PD-L1 expression, the median PFS was 4.6 vs 20.8 months for pembrolizumab with and without RT, respectively (p=0.004).

Conclusions

Concurrent immunoradiotherapy for mNSCLC is safe, although larger trials are required to address which patients benefit most from RT.

Trial registration number

NCT02444741.

Optimizing current standard of care therapy for stage III non-small cell lung cancer

The management of stage III non-small cell lung cancer (NSCLC) remains complex and controversial, with a myriad of potentially feasible options. Given the diversity of non-surgical as well as surgical options, along with recent randomized data regarding adjuvant immunotherapy that has re-defined the standard of care for unresected stage III NSCLC cases, the goal of this narrative review was to provide a contemporary view at how management of these patients can be further optimized. Topics discussed include the following items: optimizing toxicity mitigation strategies (in order to avoid impaired receipt of subsequent therapies), the importance of multidisciplinary tumor boards (MTBs) and multidisciplinary clinics (MDCs), adhering to treatment approaches endorsed by national guidelines, prudently selecting patients for surgical intervention (as compared to non-operative approaches), coordination of multidisciplinary care so as to best preserve all potential therapeutic options, and addressing challenges regarding disparities in access to oncologic care. This review places particular emphasis for community and/or rural centers, which may not have the same level of resources and/or personnel as larger academic institutions. Taken together, these strategies are aimed towards the overarching goal of streamlining oncologic care for stage III NSCLC cases in light of the numerous approaches that currently exist for these patients.

Enumeration and molecular characterization of circulating tumor cells enriched by microcavity array from stage III non-small cell lung cancer patients

Background

Various methods of liquid biopsy through the sampling of blood in cancer patients allow access to minuscule amounts of tumor that can easily be sampled repeatedly throughout therapy. Circulating tumor cells (CTCs) represent shed tumor cells that can be characterized by imaging or molecular techniques using an amenable enrichment platform. Here we validate the Hitachi Chemical Micro Cavity Array (MCA) for the enrichment of CTCs from the blood of patients diagnosed with stage III non-small cell lung cancer (NSCLC). MCA is a semi-automated filtration system that enriches CTCs on the basis of size and membrane deformability rather than a biased selection of surface antigens.

Methods

CTCs were enriched from the peripheral blood of 38 patients diagnosed with stage III NSCLC at the start of chemoradiation. Two tubes of EDTA blood were collected from each patient and processed through MCA in parallel. In the first tube, CTCs were identified as pan-cytokeratin (CK)+ CD45− nucleated cells and enumerated. The second tube was depleted of leukocytes using CD45 antibody-coated magnetic microbeads before enrichment by MCA, followed by quantitative reverse transcription polymerase chain reaction (qRT-PCR) to interrogate CTC-enriched lysates for expression of 16 target mRNAs from a panel of epithelial, mesenchymal, stem-like, and cancer signaling-related genes. CTC-enriched lysates from similarly prepared peripheral blood samples from 18 healthy donors were used to define positive gene expression.

Results

CTCs were identified by imaging in 30 of 38 patient samples (79%). At least 1 target gene was positively expressed in 23 of 25 (92%) patient samples that was subjected to molecular characterization. A CTC count of ≥7 was associated with poor progression-free survival (PFS) [hazard ratio (HR) 4.24, 95% confidence interval (CI), 1.73–10.40, P=0.020] and poor overall survival (HR 8.17, 95% CI, 2.87–23.26, P<0.001). Expression of BCL2 by MCA-enriched CTCs was associated with poor PFS (HR 3.11, 95% CI, 1.18–8.22, P=0.022). Individually, CTC count and expression of BCL2 each remained statistically significant predictors of disease progression and overall survival in multivariate analysis.

Conclusions

This is the first demonstration that lysates of MCA-enriched CTCs are amenable to molecular characterization. CTCs enriched by MCA are an independent prognostic marker in NSCLC.

Radiation-induced lymphopenia during chemoradiation therapy for non-small cell lung cancer is linked with age, lung V5, and XRCC1 rs25487 genotypes in lymphocytes

BACKGROUND & PURPOSE

We investigated clinical and genetic factors associated with severe radiation-induced lymphopenia (RIL) in a randomized clinical trial of photon vs. proton radiation, with chemotherapy, for non-small cell lung cancer.

METHODS

XRCC1 rs25487 was genotyped in lymphocytes from serial peripheral blood samples. Severe RIL was defined as absolute lymphocyte count (ALC) < 0.3 × 10⁹ cells/L. Univariate and multivariate analyses were used to identify independent risk factors, which were then used to group patients for risk of severe RIL.

RESULTS

Univariate analysis of the 178 patients in this analysis showed that older age, larger tumors, higher lung V5 and mean lung dose, and higher heart V5 and mean heart dose were associated with severe RIL during treatment (P < 0.05). The XRCC1 rs25487 AA genotype was also associated with increased risk of severe RIL during treatment (AA vs. others: hazard ratio [HR] = 1.665, 95% confidence interval [CI] 1.089-2.500, P = 0.018). Multivariate analyses showed that older age (HR = 1.031, 95% CI 1.009-1.054, P = 0.005), lung V5 (HR = 1.039, 95% CI 1.023-1.055, P < 0.0001), and AA genotype (AA vs. others, HR = 1.768, 95% CI 1.165-2.684, P = 0.007) were independently associated with higher incidence of severe RIL. These three risk factors (age ≥ 56 years, lung V5 ≥ 51% and XRCC1 rs25487 AA) distinguished patients at different risk of developing severe RIL (P < 0.0001).

CONCLUSIONS

Age, lung V5 and XRCC1 rs25487 AA were all linked with risk of severe RIL. Our predictive risk model may be helpful for identifying patients at high risk of severe RIL so that treatment can be modified.

Esophageal adenocarcinoma with any component of signet ring cells portends poor prognosis and response to neoadjuvant therapy

BACKGROUND

Multiple investigations have shown inferior outcomes for esophageal cancer patients with signet ring cell (SRC) histology. Traditionally, SRC adenocarcinoma has been defined by ≥50% of the tumor composed of SRC. We hypothesized that patients with SRC even <50% would show resistance to standard multimodality therapy with poorer long-term outcomes.

METHODS

Patients treated with trimodality therapy for adenocarcinoma from 2006 to 2018 were evaluated for SRC on pretreatment biopsy specimens. Available hematoxylin and eosin slides containing SRC tumors were re-reviewed by an esophageal pathologist to quantify the percent composition of SRC.

RESULTS

SRC histology was identified on at least 1 pathologic specimen in 106 of 819 (13%) patients. Rates of pathologic complete response (pCR) among usual-type and SRC tumors were 25% (177/713) and 10% (11/106), respectively (P = .006). The pretreatment SRC components did not independently affect the rate of pCR (1%-10% SRC: 4% [2/46] pCR; 11%-49% SRC: 25% [7/28] pCR; 50%-100% SRC: 7% [2/30] pCR). Kaplan-Meier analysis demonstrated worse survival among patients with any degree of SRC present on pretreatment biopsy, as compared with usual-type esophageal adenocarcinoma (P < .0001). Cox multivariable analysis failed to identify a relationship between increasing SRC component and poorer survival.

CONCLUSIONS

We present the only known evaluation of the percentage of SRC component in esophageal carcinoma. Our data support the hypothesis that esophageal adenocarcinoma with any component of SRC are more resistant to chemoradiation with poorer survival. Pathologic reporting of esophageal adenocarcinoma should include any component of SRC. Alternative therapies in patients with any SRC component may be indicated.

Modified En Bloc Esophagectomy Compared With Standard Resection After Neoadjuvant Chemoradiation

BACKGROUND

Surgeons have shifted away from the practice of en bloc esophagectomy, particularly in the era of neoadjuvant therapies. Although some still advocate for this radical approach, contemporary data establishing its superiority are sparse. We hypothesized that a more complete, radical resection could be completed in the setting of chemoradiation without adding morbidity.

METHODS

Patients undergoing esophagectomy after neoadjuvant chemoradiation for esophageal adenocarcinoma from 2006-2018 were evaluated. Outcomes after right transthoracic en bloc esophagectomy were compared with standard esophagectomy to determine the impact on outcomes. A Cox proportional hazard model was evaluated, and logistic regression was performed to determine the impact of en bloc resection on postoperative morbidity.

RESULTS

A total of 604 patients were identified, including 133 (22%) who underwent modified en bloc esophagectomy. Positive margins were most likely to occur in standard esophagectomy (35 of 471, 7%) vs en bloc (3 of 133, 2%) (P = .026). En bloc resection yielded a greater lymph node harvest (27; interquartile range, 22-36), as compared to standard esophagectomy (22; interquartile range, 17-28), P < .001. Multivariable analysis demonstrated prolonged progression-free survival with en bloc resection (hazard ratio, 0.74; P = .041), with 3-year freedom from locoregional recurrences of 78% and 90% for standard and en bloc approaches (P = .044). There were no differences in cardiopulmonary, gastrointestinal, or wound complications, as well as leak or chylothorax.

CONCLUSIONS

Our experience demonstrates improved locoregional disease control with en bloc esophagectomy, with equivalent morbidity. Although these results may be multifactorial, including adequate clearance of both primary tumor and nodal micrometastases, this approach is safe and feasible.

Risk Prediction for Locoregional Recurrence in Epidermal Growth Factor Receptor-Mutant Stage III-pN2 Lung Adenocarcinoma after Complete Resection: A Multi-center Retrospective Study

Background: This study aimed to develop a predictive model based on the risk of locoregional recurrence (LRR) in epidermal growth factor receptor (EGFR)-mutant stage III-pN2 lung adenocarcinoma after complete resection. Methods: A total of 11,020 patients with lung surgery were screened to determine completely resected EGFR-mutant stage III-pN2 lung adenocarcinoma. Patients were excluded if they received preoperative therapy or postoperative radiation therapy (PORT). The time from surgery to LRR was recorded. Clinicopathological variables with statistical significance predicting LRR in the multivariate Cox regression were incorporated into the competing risk nomogram. Patients were then sub-grouped based on different recurrence risk as a result of the nomogram. Results: Two hundred and eighty-eight patients were enrolled, including 191 (66.3%) with unforeseen N2 (IIIA1-2), 75 (26.0%) with minimal/single station N2 (IIIA3), and 22 (7.6%) with bulky and/or multilevel N2 (IIIA4). The 2-year overall cumulative incidence of LRR was 27.2% (confidence interval [CI], 16.3%-38.0%). IIIA4 disease (hazard ratio, 2.65; CI, 1.15-6.07; P=0.022) and extranodal extension (hazard ratio, 3.33; CI, 1.76-6.30; P<0.001) were independent risk factors for LRR and were incorporated into the nomogram. Based on the nomogram, patients who did not have any risk factor (low-risk) had a significantly lower predicted 2-year incidence of LRR than those with any of the risk factors (high-risk; 4.6% vs 21.9%, P<0.001). Conclusions: Pre-treatment bulky/multilevel N2 and pathological extranodal extension are risk factors for locoregional recurrence in EGFR-mutant stage III-pN2 lung adenocarcinoma. Intensive adjuvant therapies and active follow-up should be considered in patients with any of the risk factors.

Abstract 473: Preclinical model of radiation induced lymphopenia to identify abrogation strategies to enhance cancer therapy

Radiation induced lymphopenia (RIL) is a common and yet often ignored side effect of radiation therapy that has been observed for over 100 years. Numerous studies have demonstrated the correlation between RIL and inferior overall survival outcomes in nearly all cancer types that are treated with radiation therapy. To assess the causative link between RIL and poor disease outcomes, as well as its impact on therapy response, we have developed a mouse model of RIL. Using cone beam CT based image-guided radiation targeting the mid-thorax, we showed that conventionally fractionated radiation of 2 Gy x 5 fractions caused severe and sustained lymphopenia in both C57BL/6 (Th1) and BALB/c (Th2). Increasing the radiation dose and radiation field resulted in more pronounced RIL. Enlarging the volume to include the spleen along with the thorax resulted in greater than 90% elimination of circulating lymphocytes (CD8/CD4/CD19/NK cells). However, radiation to the head resulted in only minimal lymphodepletion suggesting site specific susceptibility to the development of severe RIL. The severity of the lymphodepletion was also unperturbed by rate of blood flow as the administration of varying anesthetics that caused 5 fold differences in heart rate did not alter the severity of RIL. Functionally, RIL abrogated the immunotherapeutic effectiveness of anti-CTLA4 mAb as lymphopenic mice bearing CT26 tumors had complete lack of response to anti-CTLA4 treatment as compared to its control littermates. Similarly, animals treated with radiotherapy had nearly complete amelioration of radiotherapy effectiveness in the setting of severe RIL. However, exogenous administration of IL-15 super agonist (IL-15 SA) (IL-15 and IL-15Rα-Fc) therapy replenished cytotoxic CD8+ T killer cells and natural killer cells to control levels which restored the tumoricidal effect of radiation therapy. Taken together our study have generated the evidence for the causative link between RIL and poorer disease outcomes and presented a potential therapeutic strategy to overcome the adverse effect of RIL.

Citation Format: Amrish Sharma, Shinya Neri, Bhanu P. Venkatesulu, Steven H. Lin. Preclinical model of radiation induced lymphopenia to identify abrogation strategies to enhance cancer therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 473.

Abstract 3297: Expression of pd-l1 on circulating stromal cells predicts immunotherapy response in unresectable non-small cell lung carcinoma after definitive chemoradiotherapy

Background: Circulating stromal cells (CStCs) have been found to be common in the peripheral blood of cancer patients and hypothesized to be a blood based biomarker for monitoring cancer treatment. It has previously been described that the dynamic changes of PD-L1 expression during chemoradiotherapy (CRT) could be tracked using circulating stromal cells. However, how these changes relate to PD-L1/PD-1 immunotherapy (IMT) response is unstudied. We prospectively monitored PD-L1 expression in 2 cell types found in circulation (Circulating Tumor Cells [CTCs] and Cancer Associated Macrophage-like Cells [CAMLs]) in locally advanced non-small cell lung cancer (NSCLC) patients (pts) treated with Atezolizumab (Atezo) after definitive CRT (n=39) or in pts with CRT alone (n=40).

Methods: A 2 year single blind prospective study was undertaken in pts with locally advanced NSCLC in 40 patients treated with CRT alone, or from a phase II DETERRED trial (NCT02525757) where Atezo was added for 1 year after completing CRT (n=10), or concurrently and after CRT (n=30). Samples from 39 of 40 pts from the DETERRED study were available for analysis. Baseline blood samples (7.5 ml) were drawn prior to start of CRT (T0), and a second sample was drawn ~1 month after completing CRT (T1), but prior to induction of Atezo. Blood was processed by CellSieve™ microfilters; stained for cytokeratin/PDL1/CD45 to identify CTCs and CAMLs. PD-L1 intensity was measured and grouped by 4 scores: 0-negative, 1-low, 2-medium, & 3-high. PD-L1 levels from circulating cells were used to evaluate PFS and OS. Significance was assessed by log-rank testing.

Results: At least one CTC and/or CAML was found in 91% of available T0 samples and 96% of available T1 samples. In the 40 patients that received CRT alone, 35 pts had measurable cells at T0 and PD-L1 expression in CStCs was low (0-1) in 20 pts and high (2-3) in 15 pts. Further, at T1 PD-L1 expression in CStCs was low in 12 pts and high in 28 pts, with no relationship to PFS (T0 HR=1.1, 95%CI 0.5-2.8, p=0.96 and T1 HR=0.8, 95%CI 0.3-2.0, p=0.82) or OS (T0 HR=0.8, 95%CI 0.2-2.8, p=0.99 and T1 HR=1.1, 95%CI 0.3-3.5, p=0.84). In the patient arm that received Atezo at T0, PD-L1 expression in CStCs was low in 21 pts and high in 17 pts, with no relationship to PFS (HR=0.5, 95%CI 0.2-1.7, p=0.18) or OS (HR=1.6, 95%CI 0.4-6.0, p=0.75). However at T1, pts with high PD-L1 had significantly improved PFS response to Atezo (HR 5.4, 95%CI 1.7-17.0, p=0.009), and improved OS (HR 21.5, 95%CI 4.5-91.9, p&lt;0.001).

Conclusions: PD-L1 expression in tissue is often not used in IMT treatment decisions due to limited correlation with clinical responses. However, it has been suggested that sequential monitoring of PD-L1 expression in circulating stromal cells in blood may predict for patients who will respond to IMT. These data suggests that CRT altered PD-L1 expression, and monitoring dynamic changes of PD-L1 in CStCs may predict immunotherapy effectiveness in NSCLC after CRT.

Citation Format: Daniel L. Adams, Jianzhong He, Yawei Qiao, Kirby P. Gardner, John V. Haymach, Anne S. Tsao, Ashvathi Raghavakaimal, Cha-Mei Tang, Alexander Augustyn, Steven H. Lin. Expression of pd-l1 on circulating stromal cells predicts immunotherapy response in unresectable non-small cell lung carcinoma after definitive chemoradiotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3297.

Predicting Incomplete Resection in Non-Small Cell Lung Cancer Preoperatively: A Validated Nomogram

BACKGROUND

Patients who are surgically treated for stage I to III non-small cell lung cancer (NSCLC) have dismal prognosis after incomplete (R1-R2) resection. Our study aimed to develop a prediction model to estimate the chance of incomplete resection based on preoperative patient-, tumor-, and treatment-related factors.

METHODS

From a Dutch national cancer database, NSCLC patients who had surgical treatment without neoadjuvant therapy were selected. Thirteen possible predictors were analyzed. Multivariable logistic regression was used to create a prediction model. External validation was applied in the American National Cancer Database, whereupon the model was adjusted. Discriminatory ability and calibration of the model was determined after internal and external validation. The prediction model was presented as nomogram.

RESULTS

Of 7156 patients, 511 had an incomplete resection (7.1%). Independent predictors were histology, cT stage, cN stage, extent of surgery, and open vs thoracoscopic approach. After internal validation, the corrected C statistic of the resulting nomogram was 0.72. Application of the nomogram to an external data set of 85,235 patients with incomplete resection in 2485 patients (2.9%) resulted in a C statistic of 0.71. Calibration revealed good overall fit of the nomogram in both cohorts.

CONCLUSIONS

An internationally validated nomogram is presented providing the ability to predict the individual chance of incomplete resection in patients with stage I to III NSCLC planned for resection. In case of a high predicted risk of incomplete resection, alternative treatment strategies could be considered, whereas a low risk further supports the use of surgical procedures.

Wee1 Kinase Inhibitor AZD1775 Effectively Sensitizes Esophageal Cancer to Radiotherapy

PURPOSE

Esophageal cancer is a deadly malignancy with a 5-year survival rate of only 5% to 20%, which has remained unchanged for decades. Esophageal cancer possesses a high frequency of TP53 mutations leading to dysfunctional G1 cell-cycle checkpoint, which likely makes esophageal cancer cells highly reliant upon G2-M checkpoint for adaptation to DNA replication stress and DNA damage after radiation. We aim to explore whether targeting Wee1 kinase to abolish G2-M checkpoint sensitizes esophageal cancer cells to radiotherapy.

EXPERIMENTAL DESIGN

Cell viability was assessed by cytotoxicity and colony-forming assays, cell-cycle distribution was analyzed by flow cytometry, and mitotic catastrophe was assessed by immunofluorescence staining. Human esophageal cancer xenografts were generated to explore the radiosensitizing effect of AZD1775 in vivo.

RESULTS

The IC50 concentrations of AZD1775 on esophageal cancer cell lines were between 300 and 600 nmol/L. AZD1775 (100 nmol/L) as monotherapy did not alter the viability of esophageal cancer cells, but significantly radiosensitized esophageal cancer cells. AZD1775 significantly abrogated radiation-induced G2-M phase arrest and attenuation of p-CDK1-Y15. Moreover, AZD1775 increased radiation-induced mitotic catastrophe, which was accompanied by increased γH2AX levels, and subsequently reduced survival after radiation. Importantly, AZD1775 in combination with radiotherapy resulted in marked tumor regression of esophageal cancer tumor xenografts.

CONCLUSIONS

Abrogation of G2-M checkpoint by targeting Wee1 kinase with AZD1775 sensitizes esophageal cancer cells to radiotherapy in vitro and in mouse xenografts. Our findings suggest that inhibition of Wee1 by AZD1775 is an effective strategy for radiosensitization in esophageal cancer and warrants clinical testing.