Impact of effective dose to immune cells (EDIC) on lymphocyte nadir and survival in limited-stage SCLC

STING Agonist Delivered by Neutrophil Membrane-Coated Gold Nanoparticles Exerts Synergistic Tumor Inhibition with Radiotherapy

Radiotherapy (RT) is one of the major treatments for cancers and a promising initiator of immune response. Gold nanoparticles are a promising radiosensitizer. In this study, we sought to optimize the drug delivery efficiency of gold nanoparticles and explore their function in delivering stimulator of interferon genes (STING) agonists with or without RT. Gold nanoparticles covalent to MSA-2 (MSA-Au) were mixed with cRGD-modified neutrophil membranes to obtain M-Au@RGD-NM. We explored the treatment efficiency of M-Au@RGD-NM combined with RT. Immune cell regulation and STING pathway activation were detected. We successfully prepared M-Au@RGD-NM with significant tumor suppression by induction of ROS and the resulting DNA damage. In vivo dynamic imaging showed that M-Au@RGD-NM was mainly targeted to radiated tumors. Tumor-bearing mice showed significant tumor inhibition following a combination therapy. M-Au@RGD-NM significantly activated the STING pathway and regulated the whole-body immune response. Locally radiated tumors showed dendritic cells mature, CD8+ T cells upregulation, and M1 polarization, with systematic immune response demonstrated by CD8+ T cell infiltration in abscopal tumors. In this study, we synthesized M-Au@RGD-NM loading MSA-2. Following characterization, we found that RT-based M-Au@RGD-NM treatment achieved good antitumor effects, tumor RT enhancement, and induction of an immune response via STING activation.

Is clinical target volume necessary for locally advanced non-small cell lung cancer treated with 4D-CT intensity-modulated radiation therapy

BACKGROUND

A dosimetric evaluation is still lacking in terms of clinical target volume (CTV) omission in stage III patients treated with 4D-CT Intensity-Modulated Radiation Therapy (IMRT).

METHODS

49 stage III NSCLC patients received 4D-CT IMRT were reviewed. Target volumes and organs at risk (OARs) were re-delineated. Four IMRT plans were conducted retrospectively to deliver different prescribed dose (74 Gy-60 Gy), and with or without CTV implementation. Dose and volume histogram (DVH) parameters were collected and compared.

RESULTS

In the PTV-g 60 Gy plan (PTV-g refers to the PTV generated from the internal gross tumor volume), only 5 of 49 patients had the isodose ≥ 50 Gy line covering at least 95% of the PTV-c (PTV-c refers to the PTV generated from the internal CTV) volume. When the prescribed dose was elevated to 74 Gy to the PTV-g, 33 of 49 patients could have the isodose ≥ 50 Gy line covering at least 95% of the PTV-c volume. In terms of OARs protection, the SIB-IMRT plan showed the lowest value of V5, V20, and mean dose of lung, had the lowest V55 of esophagus, and the lowest estimated radiation doses to immune cells (EDIC). The V20, V30, and mean dose of heart was lower in the simultaneous integrated boost (SIB) IMRT (SIB-IMRT) plan than that of the PTV-c 60 Gy plan.

CONCLUSIONS

CTV omission was not suitable for stage III patients when the prescribed dose to PTV-g was 60 Gy in the era of 4D-CT IMRT. CTV omission plus high dose to PTV-g (74 Gy for example) warranted further exploration. The SIB-IMRT plan had the best protection to normal tissue including lymphocytes, and might be the optimal choice.

Proton Therapy Reduces the Effective Dose to Immune Cells in Mediastinal Hodgkin Lymphoma Patients

Purpose

Effective dose to circulating immune cells (EDIC) is associated with survival in lung and esophageal cancer patients. This study aimed to evaluate the benefit of intensity-modulated proton therapy (IMPT) for EDIC reduction compared with volumetric modulated arc therapy (VMAT) in mediastinal Hodgkin lymphoma (mHL) patients.

Materials and Methods

Ten consecutive mHL patients treated with involved-site IMPT after frontline chemotherapy were included. The mean dose to the heart, lung, and liver and the integral dose to the body were obtained, and we calculated EDIC based on these variables. The effective dose to circulating immune cells was compared between IMPT and VMAT schedules.

Results

The median EDIC was reduced from 1.93 Gy (range: 1.31-3.87) with VMAT to 1.08 Gy (0.53-2.09) with IMPT (P < .01). Integral dose reduction was the main driver of EDIC reduction with IMPT, followed by lung sparing.

Conclusion

Intensity-modulated proton therapy significantly reduced EDIC in mHL patients undergoing consolidation involved-site radiation therapy. Integral dose reduction combined with improved lung sparing was the main driver of EDIC reduction with IMPT.

Higher immune cell radiation dose is correlated with poor tumor control and survival in patients with non-small cell lung cancer receiving postoperative radiotherapy

INTRODUCTION

The estimated dose of radiation to immune cells (EDRIC) has been shown to correlate with the overall survival (OS) of patients who receive definitive thoracic radiotherapy. However, the planning target volume (PTV) may be a confounding factor. We assessed the prognostic value of EDRIC for non-small cell lung cancer (NSCLC) in patients who underwent postoperative radiotherapy (PORT) with homogeneous PTV.

METHODS

Patients with NSCLC who underwent PORT between 2004 and 2019 were included. EDRIC was computed as a function of the number of radiation fractions and mean doses to the lungs, heart, and remaining body. The correlations between EDRIC and OS, disease-free survival (DFS), locoregional-free survival (LRFS), and distant metastasis-free survival (DMFS) were analyzed using univariate and multivariate Cox models. Kaplan-Meier analysis was performed to assess the survival difference between low- and high-EDRIC groups.

RESULTS

In total, 345 patients were analyzed. The mean EDRIC was 6.26 Gy. Multivariate analysis showed that higher EDRIC was associated with worse outcomes in terms of OS (hazard ratio [HR] 1.207, P = .007), DFS (HR 1.129, P = .015), LRFS (HR 1.211, P = .002), and DMFS (HR 1.131, P = .057). In the low- and high-EDRIC groups, the 3-year OS was 81.2% and 74.0%, DFS 39.8% and 35.0%, LRFS 70.4% and 60.5%, and DMFS 73.9% and 63.1%, respectively.

CONCLUSIONS

EDRIC is an independent prognostic factor for survival in patients with NSCLC undergoing PORT. Higher doses of radiation to the immune system are associated with tumor progression and poor survival. Organs at risk for the immune system should be considered during radiotherapy planning.

Acute hospitalizations after proton therapy versus intensity-modulated radiotherapy for locally advanced non-small cell lung cancer in the durvalumab era

INTRODUCTION

It was hypothesized that use of proton beam therapy (PBT) in patients with locally advanced non-small cell lung cancer treated with concurrent chemoradiation and consolidative immune checkpoint inhibition is associated with fewer unplanned hospitalizations compared with intensity-modulated radiotherapy (IMRT).

METHODS

Patients with locally advanced non-small cell lung cancer treated between October 2017 and December 2021 with concurrent chemoradiation with either IMRT or PBT ± consolidative immune checkpoint inhibition were retrospectively identified. Logistic regression was used to assess the association of radiation therapy technique with 90-day hospitalization and grade 3 (G3+) lymphopenia. Competing risk regression was used to compare G3+ pneumonitis, G3+ esophagitis, and G3+ cardiac events. Kaplan-Meier method was used for progression-free survival and overall survival. Inverse probability treatment weighting was applied to adjust for differences in PBT and IMRT groups.

RESULTS

Of 316 patients, 117 (37%) received PBT and 199 (63%) received IMRT. The PBT group was older (p < .001) and had higher Charlson Comorbidity Index scores (p = .02). The PBT group received a lower mean heart dose (p < .0001), left anterior descending artery V15 Gy (p = .001), mean lung dose (p = .008), and effective dose to immune circulating cells (p < .001). On inverse probability treatment weighting analysis, PBT was associated with fewer unplanned hospitalizations (adjusted odds ratio, 0.55; 95% CI, 0.38-0.81; p = .002) and less G3+ lymphopenia (adjusted odds ratio, 0.55; 95% CI, 0.37-0.81; p = .003). There was no difference in other G3+ toxicities, progression-free survival, or overall survival.

CONCLUSIONS

PBT is associated with fewer unplanned hospitalizations, lower effective dose to immune circulating cells and less G3+ lymphopenia compared with IMRT. Minimizing dose to lymphocytes may be warranted, but prospective data are needed.

Determinants of radiation dose to immune cells during breast radiotherapy

BACKGROUND

The immune system has been identified as an organ at risk in esophageal and lung cancers. However, the dosimetric impact of radiotherapy on immune system exposure in patients treated for breast cancer has never been studied.

METHODS

A monocentric retrospective dosimetric study included 163 patients treated at the Institut Curie (Paris, France) between 2010 and 2016 with locoregional helical tomotherapy after conservative surgery or total mastectomy. The effective dose to the immune system (EDIC) was calculated based on diverse dosimetric parameters. The clinical and volumetric determinants of EDIC in adjuvant radiotherapy of breast cancer were analyzed.

RESULTS

The median EDIC for the population was 4.23 Gy, ranging from 1.82 to 6.19 Gy. Right-sided radiotherapy and regional lymph node irradiation were associated with significantly higher EDIC in univariate (4.38 Gy vs. 3.94 Gy, p < 0.01, and 4.27 Gy vs. 3.44 Gy, p < 0.01, respectively) and multivariate analyses (p < 0.01 and p < 0.01). Liver overexposure was the main contributor to EDIC increase in right-sided breast cancer patients (+0.38 Gy [95%CI: +0.30; +0.46]), while the integral total dose increase was the main contributor to EDIC increase in cases of regional node irradiation (+0.63 Gy [95%CI: +0.42; +0.85]).

CONCLUSION

The EDIC score during adjuvant radiotherapy after breast cancer was statistically significantly higher in the case of right-sided radiotherapy and regional lymph node irradiation. Liver irradiation is the main contributor to immune system exposure in adjuvant irradiation of right-sided breast cancer. Populations in which an association between EDIC and survival would exist have yet to be identified but could potentially include patients treated for triple-negative breast cancer with a poor response to neoadjuvant chemoimmunotherapy.

Low-dose radiation therapy mobilizes antitumor immunity: New findings and future perspectives

Radiotherapy has unique immunostimulatory and immunosuppressive effects. Although high-dose radiotherapy has been found to have systemic antitumor effects, clinically significant abscopal effects were uncommon on the basis of irradiating single lesion. Low-dose radiation therapy (LDRT) emerges as a novel approach to enhance the antitumor immune response due to its role as a leverage to reshape the tumor immune microenvironment (TIME). In this article, from bench to bedside, we reviewed the possible immunomodulatory role of LDRT on TIME and systemic tumor immune environment, and outlined preclinical evidence and clinical application. We also discussed the current challenges when LDRT is used as a combination therapy, including the optimal dose, fraction, frequency, and combination of drugs. The advantage of low toxicity makes LDRT potential to be applied in multiple lesions to amplify antitumor immune response in polymetastatic disease, and its intersection with other disciplines might also make it a direction for radiotherapy-combined modalities.

The effective radiation dose to immune cells predicts lymphopenia and inferior cancer control in locally advanced NSCLC

PURPOSE

To explore the association of the effective dose to immune cells (EDIC) with disease control, lymphopenia, and toxicity in patients with non-small cell lung cancer (NSCLC) and identify methods to reduce EDIC.

METHODS

We abstracted data from all patients with locally advanced NSCLC treated with chemoradiation with or without consolidative immunotherapy over a ten-year period. Associations between EDIC and progression-free survival (PFS) and overall survival (OS) were modeled with Cox proportional hazards and Kaplan-Meier method. Logistic regression was used to model predictors of lymphopenia and higher EDIC. Analyses were performed with EDIC as a continuous and categorical variable. Lymphopenia was graded per CTCAE v5.0.

RESULTS

Overall, 786 patients were included (228 of which received consolidative immunotherapy); median EDIC was 4.7 Gy. Patients with EDIC < 4.7 Gy had a longer median PFS (15.3 vs. 9.0 months; p < 0.001) and OS (34.2 vs. 22.4 months; p < 0.001). On multivariable modeling, EDIC correlated with inferior PFS (HR 1.08, 95 % CI 1.01-1.14, p = 0.014) and OS (HR 1.10, 95 % CI 1.04-1.18, p = 0.002). EDIC was predictive of grade 4 lymphopenia (OR 1.16, 95 % CI 1.02-1.33, p = 0.026). EDIC ≥ 4.7 Gy was associated with increased grade 2 + pneumonitis (6-month incidence: 26 % vs 20 %, p = 0.04) and unplanned hospitalizations (90-day incidence: 40 % vs 30 %, p = 0.002). Compared to protons, photon therapy was associated with EDIC ≥ 4.7 Gy (OR 5.26, 95 % CI 3.71-7.69, p < 0.001) in multivariable modeling.

CONCLUSIONS

EDIC is associated with inferior disease outcomes, treatment-related toxicity, and the development of severe lymphopenia. Proton therapy is associated with lower EDIC. Further investigations to limit radiation dose to the immune system appear warranted.

[Radiation-induced lymphopenia: Lymphocytes as a new organ at risk]

Taking the immune system into account in the fight against tumors has upset the cancer treatment paradigm in the 21st century. Combination treatment strategies associating radiotherapy with immunotherapy are being increasingly implemented in clinical practice. In this context, lymphocytes, whether lymphocytes infiltrating the tumour, circulating blood lymphocytes or lymphocytes residing within the lymph nodes, are key players in cellular and humoral anti-tumor immunity. The significant radiosensitivity of lymphocytes was demonstrated in the early 1990s. Along with the cells of the digestive mucosa, lymphocytes are thus among the most radiosensitive cell types in the body. Compared to the old practices of external radiotherapy, current intensity modulated treatments have allowed a considerable improvement in acute and late toxicity, at the cost of a significant increase in the volume irradiated at low doses. This is not without consequence on the incidence of radiation-induced lymphopenia, with prognostic implications for many tumor types. Thus, in order not to hinder the action of antitumor immunity and the efficacy of immunotherapy, it is essential to consider lymphocytes as a new organ at risk in its own right. In this development, based on current data from the literature, we will begin by justifying the necessary prevention of radiation-induced lymphopenia, before providing the tools currently known to apprehend lymphocytes as a new multicompartments. Finally, we will broaden the perspective by outlining ways to develop research in this area.

Impact of radiation dose to the immune system on disease progression and survival for early-stage non-small cell lung cancer treated with stereotactic body radiation therapy

OBJECTIVES

Although the effects of estimated dose of radiation to immune cells (EDRIC) in stage III NSCLC, LA-NSCLC, LS-SCLC and esophageal cancer on clinical outcomes have been studied, its impact in early-stage non-small cell lung cancer (ES-NSCLC) is unknown. In this study, we evaluated the role of EDRIC and identified the factors influencing EDRIC in this population.

METHODS AND MATERIALS

We retrospectively analyzed 211 pathologically confirmed ES-NSCLC patients who were treated with SBRT between 2007 and 2020. EDRIC was calculated based on the model developed by Jin et al. and improved by Ladbury et al. Kaplan-Meier method and Cox proportional hazards regression were adopted to estimate CSS, PFS, LPFS, and DMFS. Pearson correlation was used to assess the correlation between variables. We further validated our findings in an independent cohort of 119 patients with ES-NSCLC.

RESULTS

A total of 211 patients were included with median follow-up of 48 months in the training cohort. The median EDRIC was 2.178 Gy (range: 0.426-6.015). GTV showed a positive correlation with EDRIC (r = 0.707, P = 0.000). In multivariate analysis, higher EDRIC was significantly associated with worse CSS (HR = 1.468, P = 0.009) and DMFS (HR = 1.491, P = 0.016). Considering each EDRIC quartile, there was a significant difference in CSS between 1st and 4th and 1st and 3rd quartile (P = 0.000, P = 0.004, respectively); and DMFS between 1st and 4th,1st and 3rd, and 1st and 2nd quartile (P = 0.000, P = 0.000, P = 0.008, respectively). In the subgroup and validation cohort, EDRIC was also the important prognostic predictor of CSS and DMFS using multivariate analysis.

CONCLUSION

EDRIC was an independent predictor of CSS and DMFS in ES-NSCLC, and it was affected by GTV and tumor location. Though EDRIC is a critical determinant of treatment outcomes, it is quantifiable and potentially modifiable. Additional researches exploring the feasibility of achieving lower EDRIC while maintaining adequate tumor coverage during radiotherapy are warranted.

Pericardial irradiation dose may be strongly associated with grade 4 lymphopenia and affect prognosis in patients with locally advanced esophageal cancer receiving definitive concurrent chemoradiotherapy

BACKGROUND

The immune system may influence prognosis, and lymphopenia is a frequent side effect of concurrent chemoradiotherapy (CCRT). Radical irradiation for locally advanced esophageal cancer (LA-EC) exposes significant vascular and heart volumes. In this study, we hypothesized that lymphopenia is linked to cardiac and pericardial doses and affects patient prognosis.

METHODS AND MATERIALS

We identified 190 LA-EC patients who received radical CCRT. Multivariate analysis (MVA) was performed to correlate clinical factors and dosimetric parameters with overall survival (OS). We collected lymphocyte-related variables and ratios before and during CCRT. MVA was performed to correlate hematologic toxicity with OS. The relationship between dosimetric parameters and G4 lymphopenia was determined using logistic stepwise regression. Finally, a nomogram of G4 lymphopenia was developed and validated externally.

RESULTS

Median follow-up time for all patients was 27.5 months. On MVA for OS, higher pericardial V30 (PV30 ) was linked to worse survival (HR: 1.013, 95% CI: 1.001-1.026, p = 0.039). The median OS stratified by PV30  > 55.3% and PV30  ≤ 55.3% was 24.0 months and 54.0 months, respectively (p = 0.004). G4 lymphopenia was shown to be linked with worse OS in the MVA of hematological toxicity with OS (HR: 2.042, 95% CI: 1.335-3.126, p = 0.001). Thirty of the 100 patients in the training set had G4 lymphopenia. Logistic stepwise regression was used to identify variables associated with G4 lymphopenia, and the final model consisted of stage-IVA (p = 0.017), platelet-to-lymphocyte ratio during CCRT (p = 0.008), Heart V50 (p = 0.046), and PV30 (p = 0.048). Finally, a nomogram predicting G4 lymphocytopenia were constructed and externally validated. The ROC curve showed an AUC for internal validation of 0.775 and external validation of 0.843.

CONCLUSION

Higher doses of pericardial radiation might affect LA-EC patients' prognosis by inducing G4 lymphopenia during CCRT. Further prospective studies are warranted to confirm these findings, especially in the era of immune-checkpoint inhibitor treatment.

Prophylactic cranial irradiation-related lymphopenia affects survival in patients with limited-stage small cell lung cancer

Background

The study aimed to identify the relations of the absolute lymphocyte count (ALC) nadir during prophylactic cranial irradiation (PCI) and patient outcomes in limited-stage small cell lung cancer (LS-SCLC).

Methods

We analyzed 268 L S-SCLC patients who underwent PCI from 2012 to 2019. ALC values were collected prior, during, and 3 months post PCI. Kaplan-Meier and Cox regression analyses were performed to assess the relation of ALC to patient prognosis. Two nomograms were developed on the basis of clinical variables for survival prediction.

Results

Compared with the ALC before PCI (1.13 × 10⁹ cells/L), the ALC nadir during PCI was significantly reduced by 0.68 × 10⁹ cells/L (P < 0.001) and raised to 1.02 × 10⁹ cells/L 3 months post PCI. Patients with a low ALC nadir during PCI (<0.68 × 10⁹ cells/L) had inferior progression free survival (PFS) (median PFS: 17.2 m vs. 43.7 m, P = 0.019) and overall survival (OS) (median OS: 29.0 m vs 39.1 m, P = 0.012). Multivariate Cox analysis revealed that age, smoking history, clinical stage, and ALC nadir were independent OS (P = 0.006, P = 0.005, P < 0.001 and P = 0.027, respectively), as well as independent PFS predictors (P = 0.032, P = 0.012, P = 0.012 and P = 0.018, respectively). After internal cross-validation, the corrected concordance indices of the predictive nomograms for PFS and OS were 0.637 and 0.663, respectively.

Conclusion

LS-SCLC patients with a low ALC nadir during PCI likely have worse survival outcomes. Dynamic evaluation of the ALC during PCI is recommended for LS-SCLC patients.

Higher radiation dose on immune cells is associated with radiation-induced lymphopenia and worse prognosis in patients with locally advanced esophageal squamous cell carcinoma

Background

To explore the effective dose to immune cells (EDIC) for better prognosis while avoiding radiation-induced lymphopenia (RIL) in patients with locally advanced esophageal squamous cell carcinoma (ESCC).

Materials and methods

Overall, 381 patients with locally advanced ESCC receiving definitive radiotherapy with or without chemotherapy (dRT ± CT) between 2014 and 2020 were included in this study. The EDIC model was calculated by radiation fraction number and mean doses to the heart, lung, and integral body. The correlation between EDIC and clinical outcomes was analyzed using Cox proportional hazards regression, and risk factors for RIL were determined by logistic regression analysis.

Results

The median EDIC was 4.38 Gy. Multivariate analysis revealed that low-EDIC significantly improved the OS of patients when compared with high-EDIC (HR = 1.614, P = 0.003) and PFS (HR = 1.401, P = 0.022). Moreover, high-EDIC was associated with a higher incidence of grade 4 RIL (OR = 2.053, P = 0.007) than low-EDIC. In addition, we identified body mass index (BMI), tumor thickness, and nodal stage as independent prognostic factors of OS and PFS, while BMI (OR = 0.576, P = 0.046) and weight loss (OR = 2.214, P = 0.005) as independent risk factors of grade 4 RIL. In subgroup analyses, the good group had better clinical outcomes than the remaining two groups (P< 0.001).

Conclusion

This study demonstrated that EDIC significantly correlates with poor clinical outcomes and severe RIL. Optimizing treatment plans to decrease the radiation doses to immune cells is critical for improving the outcomes.

Severe Radiation-Induced Lymphopenia Affects the Outcomes of Esophageal Cancer: A Comprehensive Systematic Review and Meta-Analysis

Simple Summary

Radiotherapy is as an important part of esophageal cancer (EC) treatment. However, it often causes severe radiation-induced lymphopenia (RIL). The aim of the current study was to evaluate the influence of severe RIL on the outcomes of EC. A systematic review and meta-analysis including 17 studies was performed. Our meta-analysis found that severe RIL was associated with a lower pathologic complete response rate and inferior overall survival and progression-free survival of EC patients. The lymphocyte nadir was found during 4–6 weeks after the start of radiotherapy. A series of dosimetric factors and clinical factors associated with RIL were summarized. Our results provide important evidence for the clinical application of radiotherapy. Minimizing the dosimetric risk factors, especially in patients with clinical risk factors, might benefit their outcomes. Our results might also offer clues for the strategy of combining radiotherapy and immunotherapy in EC patients.

Abstract

The aim of the current study was to evaluate the influence of severe radiation-induced lymphopenia (RIL) on the outcomes of esophageal cancer (EC). A systematic review and meta-analysis was performed through the PRISMA guideline. Seventeen studies were included in the current systematic review, with eight included in the meta-analyses. Meta-analyses found that severe RIL was associated with lower pathologic complete response (pCR) rate (odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.30–0.66, I² = 0%), inferior overall survival (OS) (hazard ratio (HR) = 1.50, 95% CI = 1.29–1.75, I² = 6%), and worse progression-free survival (PFS) (HR = 1.70, 95% CI = 1.39–2.07, I² = 0%) of EC patients. The lymphocyte nadir was found during 4–6 weeks after the start of radiotherapy. The leading dosimetric factors associated with severe RIL included larger PTV, higher dose to heart and body, and higher effective dose to the immune cells (EDIC). Clinical risk factors for RIL mainly comprised lower baseline ALC, higher tumor length and clinical stage, and distal EC. In conclusion, severe RIL might be associated with a lower pCR rate and worse OS and PFS of EC patients. Minimizing the dosimetric risk factors, especially in patients with clinical risk factors, might benefit their outcomes.