Treatment-related lymphopenia in patients with stage III non-small-cell lung cancer

Hypofractionated Radiotherapy-Related Lymphopenia Is Associated With Worse Survival in Unresectable Intrahepatic Cholangiocarcinoma

OBJECTIVE

The aim of this study was to evaluate the incidence of radiotherapy (RT)-related lymphopenia, its predictors, and association with survival in unresectable intrahepatic cholangiocarcinoma (ICC) treated with hypofractionated-RT (HF-RT).

METHODS

Retrospective analysis of 96 patients with unresectable ICC who underwent HF-RT (median 58.05 Gy in 15 fractions) between 2009 and 2022 was performed. Absolute lymphocyte count (ALC) nadir within 12 weeks of RT was analyzed. Primary variable of interest was severe lymphopenia, defined as Grade 3+ (ALC <0.5 k/μL) per CTCAE v5.0. Primary outcome of interest was overall survival (OS) from RT.

RESULTS

Median follow-up was 16 months. Fifty-two percent of patients had chemotherapy pre-RT, 23% during RT, and 40% post-RT. Pre-RT, median ALC was 1.1 k/μL and 5% had severe lymphopenia. Post-RT, 68% developed RT-related severe lymphopenia. Patients who developed severe lymphopenia had a significantly lower pre-RT ALC (median 1.1 vs. 1.5 k/μL, P =0.01) and larger target tumor volume (median 125 vs. 62 cm 3 , P =0.02). In our multivariable Cox model, severe lymphopenia was associated with a 1.7-fold increased risk of death ( P =0.04); 1-year OS rates were 63% vs 77% ( P =0.03). Receipt of photon versus proton-based RT (OR=3.50, P =0.02), higher mean liver dose (OR=1.19, P <0.01), and longer RT duration (OR=1.49, P =0.02) predicted severe lymphopenia.

CONCLUSIONS

HF-RT-related lymphopenia is an independent prognostic factor for survival in patients with unresectable ICC. Patients with lower baseline ALC and larger tumor volume may be at increased risk, and use of proton therapy, minimizing mean liver dose, and avoiding treatment breaks may reduce RT-related lymphopenia.

Novel time-synchronized immune-guided partial tumor irradiation: Proof of principle trial

BACKGROUND AND PURPOSE

Radiotherapy for bulky tumors often results in palliation with suboptimal outcomes. The prognosis is worsened by immunosuppression caused by radio-chemotherapy, negatively impacting on survival. Novel Partial Tumor Irradiation (PTI) was designed to spare the Peritumoral Immune Microenvironment (PIM) and to be delivered synchronously with immune activity peaks, thus enhancing both local and distant tumor control through immunostimulation.

MATERIALS AND METHODS

Present proof-of-principle trial enrolled 26 patients with bulky tumors, comparing outcomes between treatments administered at immune activity peaks versus troughs. The primary endpoint was local-bystander and distal-abscopal response-rate. Secondary endpoints included overall-, progression-free-, cancer-specific survival, neoadjuvant and immunomodulatory potential.

RESULTS

All measured outcomes were significantly influenced by treatment-timing. The bystander and abscopal response rates were 77% and 41%, respectively. PTI significantly upregulated pro-inflammatory and cell-death-inducing pathways improving the efficacy of radiotherapy by highly complex tumors.

CONCLUSIONS

This study highlights the profound impact PTI can have on a highly palliative patient cohort previously deemed beyond therapeutic hope. With 41 % of these patients still alive after a median follow-up of 50 months, PTI offers a potential lifeline for those facing advanced, treatment-resistant cancers. This approach generated also distant immunogenic anti-tumor responses, offering a promising new avenue for the treatment of advanced cancers.

The impact of different modalities of chemoradiation therapy and chemotherapy regimens on lymphopenia in patients with locally advanced non-small cell lung cancer

Background

Chemotherapy and radiotherapy (RT) would induce lymphopenia, leading to a poor prognosis. This study investigated whether chemotherapy increased lymphopenia during RT and explored the impacts of different chemotherapy regimens on the lymphocyte counts of patients receiving RT.

Methods

Clinical parameters and lymphocyte data were collected from 215 patients with locally advanced non-small cell lung cancer (LA-NSCLC). Severe lymphopenia (SRL) was defined as an absolute lymphocyte count (ALC) of ≤0.2×103 cells/μL. Patient overall survival (OS) was analyzed using the Kaplan-Meier method. The predictors of SRL were extracted using univariate and multivariate regression analyses with backward likelihood ratio elimination.

Results

Compared with patients without SRL, patients with SRL with LA-NSCLC showed a poorer prognosis in terms of OS (P=0.003). Of the 215 patients, 130 underwent concurrent chemoradiotherapy (CCRT) and 85 underwent sequential chemoradiotherapy (SCRT). The OS was better in patients without SRL (in the CCRT group, P=0.01 and in the SCRT group, P=0.08). The mean ALCs for CCRT and SCRT did not differ significantly (P=0.27). The minimum ALC of CCRT was significantly lower than that of SCRT (P<0.0001). CCRT was a predictor of SRL (P=0.008). However, multivariate analysis showed that the different chemotherapy regimens were not predictors of SRL (all P>0.1).

Conclusions

In LA-NSCLC, the outcomes of patients with SRL were poorer than those without SRL. RT and chemotherapy were the main factors affecting SRL development, while different chemotherapy regimens were not significantly associated with lymphocyte counts in LA-NSCLC.

Predicting radiation-induced immune suppression in lung cancer patients treated with stereotactic body radiation therapy

BACKGROUND

Stereotactic body radiation therapy (SBRT) is known to modulate the immune system and contribute to the generation of anti-tumor T cells and stimulate T cell infiltration into tumors. Radiation-induced immune suppression (RIIS) is a side effect of radiation therapy that can decrease immunological function by killing naive T cells as well as SBRT-induced newly created effector T cells, suppressing the immune response to tumors and increasing susceptibility to infections.

PURPOSE

RIIS varies substantially among patients and it is currently unclear what drives this variability. Models that can accurately predict RIIS in near real time based on treatment plan characteristics would allow treatment planners to maintain current protocol specific dosimetric criteria while minimizing immune suppression. In this paper, we present an algorithm to predict RIIS based on a model of circulating blood using early stage lung cancer patients treated with SBRT.

METHODS

This Python-based algorithm uses DICOM data for radiation therapy treatment plans, dose maps, patient CT data sets, and organ delineations to stochastically simulate blood flow and predict the doses absorbed by circulating lymphocytes. These absorbed doses are used to predict the fraction of lymphocytes killed by a given treatment plan. Finally, the time dependence of absolute lymphocyte count (ALC) following SBRT is modeled using longitudinal blood data up to a year after treatment. This model was developed and evaluated on a cohort of 64 patients with 10-fold cross validation.

RESULTS

Our algorithm predicted post-treatment ALC with an average error of0.24 ± 0.21 × 10 9 $0.24 \pm 0.21 \times {10}^9$ cells/L with 89% of the patients having a prediction error below 0.5 × 109 cells/L. The accuracy was consistent across a wide range of clinical and treatment variables. Our model is able to predict post-treatment ALC < 0.8 (grade 2 lymphopenia), with a sensitivity of 81% and a specificity of 98%. This model has a ∼38-s end-to-end prediction time of post treatment ALC.

CONCLUSION

Our model performed well in predicting RIIS in patients treated using lung SBRT. With near-real time model prediction time, it has the capability to be interfaced with treatment planning systems to prospectively reduce immune cell toxicity while maintaining national SBRT conformity and plan quality criteria.

The relationship between splenic dose and radiation-induced lymphopenia

Lymphocytes, which are highly sensitive to radiation, play a crucial role in the body's defense against tumors. Radiation-induced lymphopenia has been associated with poorer outcomes in different cancer types. Despite being the largest secondary lymphoid organ, the spleen has not been officially designated as an organ at risk. This study hypothesizes a connection between spleen irradiation and lymphopenia and seeks to establish evidence-based dosage limits for the spleen. We retrospectively analyzed data from 96 patients with locally advanced gastric cancer who received postoperative chemoradiotherapy (CRT) between May 2010 and May 2017. Complete blood counts were collected before, during and after CRT. We established a model for predicting the minimum absolute lymphocyte count (Min ALC) and to investigate potential associations between spleen dosimetric variables and Min ALC. The median follow-up was 60 months. The 5-year overall survival (OS) and disease-free survival (DFS) were 65.2% and 56.8%, respectively. The median values of pre-treatment ALC, Min ALC and post-treatment ALC were 1.40 × 109, 0.23 × 109 and 0.28 × 109/L, respectively. Regression analysis confirmed that the primary tumor location, number of fractions and spleen V5 were significant predictors of Min ALC during radiation therapy. Changes in ALC (ΔALC) were identified as an independent predictor of both OS and DFS. Spleen V5 is an independent predictor for Min ALC, and the maximum dose of the spleen is associated with an increased risk of severe lymphopenia. Therefore, these doses should be restricted in clinical practice. Additionally, ΔALC can serve as a prognostic indicator for adjuvant radiotherapy in gastric cancer.

Radiation Therapy and Myeloid-Derived Suppressor Cells: Breaking Down Their Cancerous Partnership

Radiation therapy (RT) has been a primary treatment modality in cancer for decades. Increasing evidence suggests that RT can induce an immunosuppressive shift via upregulation of cells such as tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs). MDSCs inhibit antitumor immunity through potent immunosuppressive mechanisms and have the potential to be crucial tools for cancer prognosis and treatment. MDSCs interact with many different pathways, desensitizing tumor tissue and interacting with tumor cells to promote therapeutic resistance. Vascular damage induced by RT triggers an inflammatory signaling cascade and potentiates hypoxia in the tumor microenvironment (TME). RT can also drastically modify cytokine and chemokine signaling in the TME to promote the accumulation of MDSCs. RT activation of the cGAS-STING cytosolic DNA sensing pathway recruits MDSCs through a CCR2-mediated mechanism, inhibiting the production of type 1 interferons and hampering antitumor activity and immune surveillance in the TME. The upregulation of hypoxia-inducible factor-1 and vascular endothelial growth factor mobilizes MDSCs to the TME. After recruitment, MDSCs promote immunosuppression by releasing reactive oxygen species and upregulating nitric oxide production through inducible nitric oxide synthase expression to inhibit cytotoxic activity. Overexpression of arginase-1 on subsets of MDSCs degrades L-arginine and downregulates CD3ζ, inhibiting T-cell receptor reactivity. This review explains how radiation promotes tumor resistance through activation of immunosuppressive MDSCs in the TME and discusses current research targeting MDSCs, which could serve as a promising clinical treatment strategy in the future.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Blood Lymphocytes as a Prognostic Factor for Stage III Non-Small Cell Lung Cancer with Concurrent Chemoradiation

We aimed to identify blood lymphocytes as a prognostic factor for survival in patients with locally advanced stage III non-small cell lung cancer (NSCLC) treated with concurrent chemoradiotherapy (CCRT). This is a secondary study of 196 patients enrolled in the Korean Radiation Oncology Group 0903 phase III clinical trial to evaluate the prognostic significance of circulating blood lymphocyte levels. The median total lymphocyte count (TLC) reduction ratio during CCRT was 0.74 (range: 0.29-0.97). In multivariate analysis, patient age (p=0.014) and gross tumor volume (GTV, p=0.031) were significant factors associated with overall survival, while TLC reduction (p=0.018) and pretreatment neutrophil-to-lymphocyte ratio (NLR; p=0.010) were associated with progression-free survival (PFS). In multivariate logistic regression analysis, pretreatment NLR, GTV, and heart V20 were significantly associated with TLC reduction. Immunohistochemical analysis of programmed death ligand 1 and CD8 expression on T cells was performed on 84 patients. CD8 expression was not significantly associated with the pretreatment lymphocyte count (p=0.673), and PDL1 expression was not significantly associated with OS or PFS. Univariate analysis revealed that high CD8 expression in TILs was associated with favorable OS and was significantly associated with favorable PFS (p=0.032). TLC reduction during CCRT is a significant prognostic factor for PFS, and heart V20 is significantly associated with TLC reduction. Thus, in the era of immunotherapy, constraining the volume of the radiation dose to the whole heart must be prioritized for the better survival outcomes.

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.

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

Background

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

Methods

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

Results

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

Conclusion

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

Genetic architecture of the acute and persistent immune cell response after radiation exposure

Hematologic toxicity is a common side effect of multimodal cancer therapy. Nearly all animal studies investigating the causes of radiotherapy-induced hematologic toxicity use inbred strains with limited genetic diversity and do not reflect the diverse responses observed in humans. We used the population-based Collaborative Cross (CC) mouse resource to investigate the genetic architecture of the acute and persistent immune response after radiation exposure by measuring 22 immune parameters in 1,720 CC mice representing 35 strains. We determined relative acute and persistent radiation resistance scores at the individual strain level considering contributions from all immune parameters. Genome-wide association analysis identified quantitative trait loci associated with baseline and radiation responses. A cross-species radiation resistance score predicted recurrence-free survival in medulloblastoma patients. We present a community resource of immune parameters and genome-wide association analyses before and after radiation exposure for future investigations of the contributions of host genetics on radiosensitivity.

Dosimetric Effect of Thymus and Thoracic Duct on Radiation-Induced Lymphopenia in Patients With Primary Lung Cancer Who Received Thoracic Radiation

Purpose

Radiation-induced lymphopenia is a well-recognized factor for tumor control and survival in patients with cancer. This study aimed to determine the role of radiation dose to the thymus and thoracic duct on radiation-induced lymphopenia.

Methods and Materials

Patients with primary lung cancer treated with thoracic radiation therapy between May 2015 and February 2020 with whole blood count data were eligible. Clinical characteristics, including age, gender, histology, stage, chemotherapy regimen, radiation dosimetry, and absolute lymphocyte count (ALC) were collected. The thymus and thoracic duct were contoured by one investigator for consistency and checked by one senior physician. The primary endpoint was radiation-induced decrease in lymphocytes, defined as the difference in ALC (DALC) before and after radiation therapy.

Results

The data of a total of 116 consecutive patients were retrospectively retrieved. Significant correlations were found between DALC and several clinical factors. These factors include stage, chemotherapy or concurrent chemoradiation, biologically effective dose (BED), mean lung dose, mean body dose, effective dose to immune cells (EDIC), mean thymus dose (MTD), and mean thoracic duct dose (MTDD) (all P < .05). Ridge regression showed that DALC = 0.0063 × BED + 0.0172 × EDIC + 0.0002 × MTD + 0.0147 × MTDD + 0.2510 (overall P = .00025 and F = 5.85). The combination model has the highest area under the curve of 0.77 (P < .001) when fitting the logistic regression model on DALC categorized as binary endpoint. The sensitivity and specificity of the combined model were 89% and 58%, respectively.

Conclusions

This study demonstrated for the first time that radiation doses to the thymus and thoracic duct are strongly associated with radiation-induced lymphopenia patients with lung cancer. Further validation studies are needed to implement thymus and thoracic duct as organs at risk.

Hypofractionated Radiotherapy followed by Hypofractionated Boost with weekly concurrent chemotherapy for Unresectable Stage III Non-Small Cell Lung Cancer: Results of A Prospective Phase II Study (GASTO-1049)

PURPOSE

We launched a prospective phase 2 clinical trial to explore the safety and efficacy of hypofractionated radiation therapy (hypo-RT) followed by hypofractionated boost (hypo-boost) combined with concurrent weekly chemotherapy in patients with unresectable locally advanced non-small cell lung cancer (LA-NSCLC).

METHODS AND MATERIALS

Patients with newly diagnosed LA-NSCLC with unresectable stage III disease were recruited between June 2018 and June 2020. Patients were treated with hypo-RT (40 Gy in 10 fractions) followed by hypo-boost (24-28 Gy in 6-7 fractions) combined with concurrent weekly chemotherapy (docetaxel 25 mg/m2 and nedaplatin 25 mg/m2). The primary endpoint of the study was progression-free survival (PFS), and the secondary endpoints included overall survival (OS), locoregional failure-free survival (LRFS), distant metastasis-free survival (DMFS), objective response rate (ORR), and toxicities.

RESULTS

From June 2018 to June 2020, 75 patients were enrolled with a median follow-up duration of 28.0 months. The ORR of the whole cohort was 94.7%. Disease progression or death was recorded in 44 (58.7%) patients, with a median PFS of 21.6 months (95% confidence interval [CI], 15.6-27.6 months). The 1- and 2-year PFS rates were 81.3% (95% CI, 72.5%-90.1%) and 43.3% (95% CI, 31.5%-55.1%), respectively. The median OS, DMFS, and LRFS had not been reached at the time of the last follow-up. The 1- and 2-year OS rates were 94.7% (95% CI, 89.6%-99.8%) and 72.4% (95% CI, 62.0%-82.8%), respectively. The most frequent acute nonhematologic toxicity was radiation esophagitis. Grade (G) 2 and G3 acute radiation esophagitis were observed in 20 (26.7%) and 4 (5.3%) patients, respectively. Thirteen patients (13/75, 17.3%) had G2 pneumonitis and no G3-G5 acute pneumonitis occurred during follow-up.

CONCLUSIONS

Hypo-RT followed by hypo-boost combined with concurrent weekly chemotherapy could yield satisfactory local control and survival outcomes with moderate radiation-induced toxicity in patients with LA-NSCLC. The new potent hypo-CCRT regimen significantly shortened treatment time and provided the potential opportunity for the combination of consolidative immunotherapy.

Prognostic impact of radiotherapy-induced-lymphopenia in patients treated with breast-conservative surgery

We investigated a prognostic impact of radiotherapy-induced lymphopenia (RIL) in breast cancer patients treated with breast-conservative surgery (BCS). We included 531 breast cancer patients who were treated with BCS and adjuvant radiotherapy. None of these received (neo)adjuvant chemotherapy. Pre- and post- absolute lymphocyte counts (ALC) were reviewed before and after radiotherapy. The primary endpoint was to evaluate recurrence-free survival (RFS) according to the pre-to-post ALC ratio. Binary logistic regression model was used to identify risk factors for RIL. Either continuous or categorical (> 2.4) pre-to-post ALC ratio was associated with RFS. In 531 patients receiving whole breast irradiation (WBI) and regional nodal irradiation (RNI), RFS was significantly reduced in the patients with high pre-to-post ALC ration (> 2.4). In multivariable analysis, low pre-to-post post ALC ratio was significantly related to decreased RFS in the multivariable analysis (HR 2.293, 95% CIs 1.110-4.735, P = 0.025). In 452 patients treated with WBI alone, high pre-to-post ALC ratio was still significantly associated with decreased RFS in the multivariable analysis (HR 2.708, 95% CIs 1.016-7.218, P = 0.046). In binary logistic regression analysis, RNI was only significant risk factor for clinically meaningful RIL. Our findings show that a markedly decrease in ALC during radiotherapy has a negative prognostic impact.

Circulating immune cell dynamics as outcome predictors for immunotherapy in non-small cell lung cancer

The use of immune checkpoint inhibitors (ICIs) continues to transform the therapeutic landscape of non-small cell lung cancer (NSCLC), with these drugs now being evaluated at every stage of the disease. In contrast to these advances, little progress has been made with respect to reliable predictive biomarkers that can inform clinicians on therapeutic efficacy. All current biomarkers for outcome prediction, including PD-L1, tumor mutational burden or complex immune gene expression signatures, require access to tumor tissue. Besides the invasive nature of the sampling procedure, other disadvantages of tumor tissue biopsies are the inability to capture the complete spatial heterogeneity of the tumor and the difficulty to perform longitudinal follow-up on treatment. A concept emerges in which systemic immune events developing at a distance from the tumor reflect local response or resistance to immunotherapy. The importance of this cancer 'macroenvironment', which can be deciphered by comprehensive analysis of peripheral blood immune cell subsets, has been demonstrated in several cutting-edge preclinical reports, and is corroborated by intriguing data emerging from ICI-treated patients. In this review, we will provide the biological rationale underlying the potential of blood immune cell-based biomarkers in guiding treatment decision in immunotherapy-eligible NSCLC patients. Finally, we will describe new techniques that will facilitate the discovery of more immune cell subpopulations with potential to become predictive biomarkers, and reflect on ways and the remaining challenges to bring this type of analysis to the routine clinical care in the near future.

Impact of radiation on host immune system in patients treated with chemoradiotherapy and durvalumab consolidation for unresectable locally advanced non-small cell lung cancer

Background

The optimal modalities of radiotherapy when combining concurrent chemoradiation (CCRT) and immunotherapy (IO) for locally advanced non-small cell lung cancer (LA-NSCLC) remain to be determined. The aim of this study was to investigate the impact of radiation on different immune structures and immune cells in patients treated with CCRT followed by durvalumab.

Material and methods

Clinicopathologic data, pre- and post-treatment blood counts, and dosimetric data were collected in patients treated with CCRT and durvalumab consolidation for LA-NSCLC. Patients were divided into two groups according to the inclusion (NILN-R+) or not (NILN-R-) of at least one non-involved tumor-draining lymph node (NITDLN) in the clinical target volume (CTV). Progression-free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method.

Results

Fifty patients were included with a median follow-up of 23.2 months (95% CI 18.3-35.2). Two-year PFS and 2-year OS were 52.2% (95% CI 35.8-66.3) and 66.2% (95% CI 46.5-80.1), respectively. In univariable analysis, NILN-R+ (hazard ratio (HR) 2.60, p = 0.028), estimated dose of radiation to immune cells (EDRIC) >6.3 Gy (HR 3.19, p = 0.049), and lymphopenia ≤ 500/mm³ at IO initiation (HR 2.69, p = 0.021) were correlated with poorer PFS; lymphopenia ≤ 500/mm³ was also associated with poorer OS (HR 3.46, p = 0.024). In multivariable analysis, NILN-R+ was the strongest factor associated with PFS (HR 3.15, p = 0.017).

Conclusion

The inclusion of at least one NITDLN station within the CTV was an independent factor for poorer PFS in the context of CCRT and durvalumab for LA-NSCLC. The optimal sparing of immune structures might help in achieving better synergy between radiotherapy and immunotherapy in this indication.

Severe lymphopenia as a prognostic factor in rectal cancer patients receiving adjuvant chemoradiotherapy: a retrospective study

The relationship between total lymphocyte counts (TLCs) and survival is not well documented in rectal cancer. This study aimed to investigate the association between TLCs and disease-free survival (DFS) and identify factors associated with lymphopenia in locally advanced rectal cancer patients receiving chemoradiotherapy. Thirty-six patients with locally advanced rectal cancer were retrospectively analyzed. TLCs were evaluated before surgery (pre-S), before radiotherapy (pre-RT), and during concurrent chemoradiotherapy (CCRT). The relationship between TLCs and DFS was analyzed by univariate and multivariate analysis. Potential clinical factors associated with lymphopenia were also evaluated. Median TLC declined significantly during radiotherapy. Severe lymphopenia during CCRT was significantly associated with poorer DFS on Kaplan-Meier analysis (p = 0.01), univariate regression analysis (p = 0.036), and multivariate regression analysis (p = 0.038). Pre-S TLCs (p = 0.009) and pre-RT TLCs (p = 0.042) were significantly associated with severe lymphopenia on univariate regression analysis; however, only pre-S TLCs (p = 0.026) were significantly associated with severe lymphopenia on multivariate regression analysis. Severe lymphopenia was a predictor of poorer DFS in patients with locally advanced rectal cancer receiving adjuvant chemoradiotherapy. Pre-S TLCs were predictors of severe lymphopenia. Further study is warranted to reduce the rate of severe lymphopenia.

Effects of lymphopenia on survival in proton therapy with chemotherapy for non-small cell lung cancer

Lymphocytes play an important role in the cancer immune system. In the present study, we aimed to evaluate the associations of lymphopenia during proton beam therapy (PBT) and concurrent chemotherapy with clinical outcomes and to determine whether lung or bone is more influential on lymphopenia during PBT. Data from 41 patients with stage III non-small cell lung cancer (NSCLC) who received PBT of 74 GyE with concurrent chemotherapy between 2007 and 2017 were reviewed retrospectively. The correlation between dosimetry parameters obtained from dose-volume histograms of the bone and lung and lymphopenia during PBT were analyzed. Minimum absolute lymphocyte count (ALCmin) and maximum neutrophil/lymphocyte ratio (NLRmax) were used as indicators of lymphopenia. Bone V5-20 and lung V5-50 were significantly correlated with the ALCmin and NLRmax during PBT. Multivariable analysis showed that the NLRmax, but not the ALCmin, was associated with overall survival (OS), progression-free survival (PFS) and distant metastasis-free survival (DMFS). The 3-year rates of OS, PFS and DMFS of patients with a low (≤ 6.3) versus high (> 6.3) NLRmax were 73.9% vs 44.4% (P = 0.042), 26.1% vs 5.6% (P = 0.022) and 39.1% vs 5.6% (P < 0.001), respectively. Lung V20 was significantly associated with DMFS on multivariable analyses (hazard ratio: 1.094, P = 0.008), whereas bone V5 had no impact on survival outcomes. We concluded that the NLRmax was a better prognostic indicator than the ALCmin, and the lung dose had more influence than the bone dose on the main survival outcomes in stage III NSCLC patients treated with PBT combined with concurrent chemotherapy.

Neural network based ensemble model to predict radiation induced lymphopenia after concurrent chemo-radiotherapy for non-small cell lung cancer from two institutions

The use of adjuvant Immune Checkpoint Inhibitors (ICI) after concurrent chemo-radiation therapy (CCRT) has become the standard of care for locally advanced non-small cell lung cancer (LA-NSCLC). However, prolonged radiotherapy regimens are known to cause radiation-induced lymphopenia (RIL), a long-neglected toxicity that has been shown to correlate with response to ICIs and survival of patients treated with adjuvant ICI after CCRT. In this study, we aim to develop a novel neural network (NN) approach that integrates patient characteristics, treatment related variables, and differential dose volume histograms (dDVH) of lung and heart to predict the incidence of RIL at the end of treatment. Multi-institutional data of 139 LA-NSCLC patients from two hospitals were collected for training and validation of our suggested model. Ensemble learning was combined with a bootstrap strategy to stabilize the model, which was evaluated internally using repeated cross validation. The performance of our proposed model was compared to conventional models using the same input features, such as Logistic Regression (LR) and Random Forests (RF), using the Area Under the Curve (AUC) of Receiver Operating Characteristics (ROC) curves. Our suggested model (AUC=0.77) outperformed the comparison models (AUC=0.72, 0.74) in terms of absolute performance, indicating that the convolutional structure of the network successfully abstracts additional information from the differential DVHs, which we studied using Gradient-weighted Class Activation Map. This study shows that clinical factors combined with dDVHs can be used to predict the risk of RIL for an individual patient and shows a path toward preventing lymphopenia using patient-specific modifications of the radiotherapy plan.

Haematological and renal toxicity of radiation therapy in neuroblastoma paediatric patients

PURPOSE

The objective of this study was to evaluate the renal and hematologic toxicity in paediatric patients with adrenal high-risk neuroblastoma who have received radiation therapy (RT) as part of radical treatment.

MATERIAL AND METHODS

Pediatric patients diagnosed with high-risk adrenal neuroblastoma who received RT as part of the definitive treatment between January 2004 and May 2020 in a single institution were selected. Complete blood counts (CBC) and creatinine clearance (CrCl) pre-RT and post-RT were compared through the Wilcoxon signed-rank test and correlated with survival analysis by Cox regression.

RESULTS

Forty-two children with a median age of 3 years at diagnosis and 2.8 years of follow-up were selected. A significant and acute decrease in lymphocytes was found (p = 0.002) 1 month from RT. Patients with a drop higher than 50% of the previous value experimented a significant reduction in overall survival (55 vs 10%; p = 0.031). At the end of the follow-up, a significant increase in all blood counts was observed. With respect to renal function, an acute and significant decrease in CrCl was observed tin patients younger than 4 years who received RT (p = 0.013). However, it was not clinically relevant.

CONCLUSION

Our data suggest that acute lymphopenia occurs after RT and could be associated with a poorer prognosis. Other blood counts are reduced after RT and all of them are in physiological range at the end of follow-up. Our cohort presented excellent renal outcomes without any case of chronic renal dysfunction.

Effect of lymphoid volume irradiation on radiation-induced lymphopenia in head and neck cancers

PURPOSE

Radiotherapy induces significant and prolonged lymphopenia in head and neck cancer patients with poorer outcomes and reduced survival. Irradiated volumes may be correlated with lymphopenia with a potential impact on immunotherapy efficacy. We assessed associations between volumes treated with radiotherapy and the nadir of the lymphocyte count in patients with head and neck cancer.

MATERIALS AND METHODS

We conducted a monocentric retrospective study in patients with head and neck cancer treated with radiation. Univariate analysis used regression analysis to model nadir lymphocyte count and radiotherapy volumes; multivariate analysis then modelled factors associated with nadir lymphocyte count.

RESULTS

Of the 77 included patients, 97% presented lymphopenia during radiotherapy with an average nadir of 431 cells/mm³ at a median of 40 days after the beginning of treatment. The volume of high-risk radiotherapy and gross tumour volume were correlated with nadir lymphocyte count with a Spearman coefficient of -0.267 (P=0.019) and -0.387 (P=0.001), respectively. After multivariate linear regression, high-risk radiotherapy was significantly associated with nadir lymphocyte count with a regression coefficient of -0.32 (per cubic centimetre) [95% CI=-0.60; -0.03] (P=0.028).

CONCLUSION

High-risk radiotherapy was significantly associated with nadir lymphocyte count in patients with head and neck cancer treated with radiation. Sparing lymphoid volumes from irradiation by elective nodal irradiation or proton therapy may limit lymphopenia and needs to be investigated in combination with immunotherapy.

Immune microenvironment: novel perspectives on bone regeneration disorder in osteoradionecrosis of the jaws

Osteoradionecrosis of the jaws (ORNJ) is a severe complication that occurs after radiotherapy of head and neck malignancies. Clinically, conservative treatments and surgeries for ORNJ exhibited certain therapeutic effects, whereas the regenerative disorder of the post-radiation jaw remains a pending problem to be solved. In recent years, the recognition of the role of the immune microenvironment has led to a shift from an osteoblasts (OBs) or bone marrow mesenchymal stromal cells (BMSCs)-centered view of bone regeneration to the concept of a complicated microecosystem that supports bone regeneration. Current advances in osteoimmunology have uncovered novel targets within the immune microenvironment to help improve various regeneration therapies, notably therapies potentiating the interaction between BMSCs and immune cells. However, these researches lack a thorough understanding of the immune microenvironment and the interaction network of immune cells in the course of bone regeneration, especially for the post-operative defect of ORNJ. This review summarized the composition of the immune microenvironment during bone regeneration, how the immune microenvironment interacts with the skeletal system, and discussed existing and potential strategies aimed at targeting cellular and molecular immune microenvironment components.

Radiation-induced circulating myeloid-derived suppressor cells induce systemic lymphopenia after chemoradiotherapy in patients with glioblastoma

Severe and prolonged lymphopenia frequently occurs in patients with glioblastoma after standard chemoradiotherapy and has been associated with worse survival, but its underlying biological mechanism is not well understood. To address this, we performed a correlative study in which we collected and analyzed peripheral blood of patients with glioblastoma (n = 20) receiving chemoradiotherapy using genomic and immune monitoring technologies. RNA sequencing analysis of the peripheral blood mononuclear cells (PBMC) showed an elevated concentration of myeloid-derived suppressor cell (MDSC) regulatory genes in patients with lymphopenia when compared with patients without lymphopenia after chemoradiotherapy. Additional analysis including flow cytometry and single-cell RNA sequencing further confirmed increased numbers of circulating MDSC in patients with lymphopenia when compared with patients without lymphopenia after chemoradiotherapy. Preclinical murine models were also established and demonstrated a causal relationship between radiation-induced MDSC and systemic lymphopenia using transfusion and depletion experiments. Pharmacological inhibition of MDSC using an arginase-1 inhibitor (CB1158) or phosphodiesterase-5 inhibitor (tadalafil) during radiation therapy (RT) successfully abrogated radiation-induced lymphopenia and improved survival in the preclinical models. CB1158 and tadalafil are promising drugs in reducing radiation-induced lymphopenia in patients with glioblastoma. These results demonstrate the promise of using these classes of drugs to reduce treatment-related lymphopenia and immunosuppression.

Proton and Carbon Ion Radiation Therapy Decreased Severe Lymphopenia by Reducing Thoracic Vertebra and Aortic Doses in Non-small Cell Lung Cancer Versus Intensity Modulated Radiation Therapy

PURPOSE

Lymphopenia is a common adverse effect of radiation therapy (RT). Little is known about the difference in lymphopenia between intensity modulated (photon) radiation therapy (IMRT) and proton and carbon ion radiation therapy (PCIRT). This study aimed to investigate lymphopenia differences between IMRT and PCIRT in non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Clinical and dosimetric parameters were collected from 343 patients who received definitive IMRT or PCIRT for NSCLC. Severe lymphopenia (SRL) was defined as an absolute lymphocyte count (ALC) ≤0.5 × 10³ cells/μL. Overall survival (OS) was analyzed using the Kaplan-Meier method. Propensity score matching was performed between the IMRT and PCIRT groups. Least absolute shrinkage and selection operator analysis was used to select appropriate dosimetric parameters. Univariate and multivariate logistic regression analyses were conducted to identify the predictors of SRL.

RESULTS

Compared with the IMRT group, the PCIRT group was less likely to develop SRL (P < .001). Compared with the non-SRL group, the SRL group showed significant association with poorer OS, with a median survival time of 29.2 versus 15.0 months (P = .046). IMRT was an independent risk factor of SRL (P = .004). A lower ALC before RT (P = .030) and larger planning target volume (PTV) (P = .002) were also significant independent risk factors for SRL. Moreover, the majority of dosimetric parameters of organs at risk in PCIRT were lower than those in IMRT (P < .001). Thoracic vertebra V5 (P = .002) and aorta V5 (P = .026) were identified as independent risk predictors of SRL after adding dosimetric parameters to the regression model.

CONCLUSIONS

Compared with IMRT, PCIRT could reduce SRL incidence, possibly by limiting thoracic vertebra and aortic doses, and SRL was associated with poor outcomes in patients with NSCLC.

Impact of lymphopenia on efficacy of nivolumab in head and neck cancer patients

INTRODUCTION

Lymphopenia has been correlated with poorer survival in patients with metastatic cancers treated with anti-PD-1 immunotherapy. Treatments such as chemotherapy, surgery or radiotherapy can induce lymphopenia. Radiation-induced lymphopenia is common and prolonged in head and neck cancer (HNSCC) patients. We evaluated the impact of lymphopenia, on efficacy of anti PD-1 nivolumab immunotherapy in HNSCC patients.

METHODS

a multicenter retrospective study included consecutive patients treated with nivolumab for recurrent/metastatic (R/M) HNSCC between January 2017 and June 2019. Lymphopenia was defined as lymphocyte counts below 1000 cells/mm³ upon initiation of nivolumab. Logistical regression was performed on factors associated with lymphopenia and ROC analyses assessed association between lymphopenia and survival.

RESULTS

median age was 65. Of the 100 included patients, 60% had been treated by surgery, 67% had had first-line chemotherapy, and 89% loco-regional radiotherapy, 65% had concurrent chemotherapy with radiotherapy. Lymphopenia occurred in 56 (56%) patients upon initiation of nivolumab, with 29 (29%) patients having radiation-related lymphopenia. Prior locoregional radiotherapy was the only factor associated with lymphopenia upon initiation of nivolumab by logistical regression (OR 0.144 [0.029-0.706], p - 0.017). Lymphopenia upon initiation of nivolumab did not affect progression-free survival (PFS) (p - 0.815), overall survival (OS) (p - 0.783) or disease control rate (DCR) (p - 0.125). Locoregional symptomatology (HR - 2.37 [1.24-4.54], p - 0.009), metastatic symptomatology (HR - 4.74 [2.21-10.15], and persistent lymphopenia under nivolumab (HR 3.96 [1.19-13.17] p - 0.034) were associated with poorer OS in multivariate analysis.

CONCLUSIONS

Lymphopenia upon initiation of nivolumab was not associated with poorer survival in R/M HNSCC patients, but persistence of lymphopenia during immunotherapy might be a prognostic marker of patient survival.

Lymphopenia during 177Lu-DOTATATE therapy leading to recurrence of tuberculosis: a case report

We report the case of a 72-year-old woman who presented with tuberculous arthritis during the setting of ¹⁷⁷Lu-DOTATATE therapy for a grade-2 neuro-endocrine pancreatic tumor with liver metastases. We hypothesized that this recurrence might have been related to the occurrence of lymphopenia, which is common during PRRT. Indeed, though lymphopenia is frequently dismissed, it could lead to the development of opportunistic diseases and its severity should be examined, especially in case of abnormal clinical symptoms.

Meta-analysis and Critical Review: Association Between Radio-induced Lymphopenia and Overall Survival in Solid Cancers

Purpose

Immune system modulation, with the use of immune checkpoint inhibitors, has drastically changed the field of oncology. Strong preclinical data indicate that radiation therapy (RT) may enhance the response rate to such drugs via in situ vaccination, although these data do not consider immune radiotoxicity. This meta-analysis investigates whether radio-induced lymphopenia (RIL) is associated with overall survival (OS).

Methods and Materials

A systematic literature search and quantitative analysis were planned, conducted, and reported per the Preferred Reporting Items for Systematic Reviews and Meta-analyses and Quality of Reporting of Meta-analyses checklists. The literature from January 1990 to March 2021 was searched to identify clinical studies with OS data in patients treated with RT and presenting with lymphopenia. A random-effect model was employed for the meta-analysis. Heterogeneity was assessed using the I² statistic. Publication bias was estimated using a P-curve analysis.

Results

A total of 56 studies with 13 223 patients and 11 types of cancers were selected. The mean follow-up time was 35.9 months. Over a third of patients had RIL (37.25%). After removing outlying studies (n = 14), the between-study heterogeneity variance was estimated at t² = 0.018 (P = .01) with an I² value of 36.0% (95% confidence interval, 6%-56%). The results showed that RIL was significantly associated with worse OS (hazard ratio: 1.70; 95% confidence interval, 1.55-1.86; P < .01; 95% prediction interval, 1.27-2.26). A subgroup analysis was performed based on the type of primary tumor, and a difference between the subgroups was found (P < .01). Based on the P-curve analysis, a significant evidential value was found, and no significant publication bias was identified among the studies.

Conclusions

RIL is a significant prognostic factor for mortality in virtually all solid cancers. Pooled-effect estimates indicate a significantly reduced risk of death in patients without RIL. Tailoring RT regimens to spare the immune system and updating dosimetric constraints for new organs at risk, such as major blood vessels, organs with rich blood supplies, bones, and all lymph node areas, may improve prognoses.

Hypofractionated concurrent chemoradiotherapy related lymphopenia and its association with survival in locally advanced non-small cell lung cancer patients

Background

To evaluate longitudinal changes of concurrent chemoradiotherapy (CCRT) related lymphopenia and its association with survival in locally advanced non-small cell lung cancer (LA-NSCLC) patients.

Methods

Total lymphocyte count (TLC) at baseline, weekly intervals during CCRT and monthly intervals up to 12 months after CCRT were documented. The Common Terminology Criteria for Adverse Events version 5.0 was used to grade the severity of lymphopenia. Cox regression analysis was performed to evaluate the association between overall survival (OS) and CCRT related lymphopenia at different timepoints. Logistic regression model was used to determine the clinical factors associated with TLC level.

Results

381 LA-NSCLC patients treated with definitive CCRT without consolidation therapy (NCT02573506/NCT02577341) between 2011 to 2020 were analyzed. With a median follow-up of 45.8 months, the median OS was 41.0 months for all patients. Univariable analysis demonstrated that the 3 weeks during CCRT Grade (G) 4 lymphopenia (P=0.018), 2 months after CCRT G1-4 lymphopenia (P=0.004), 6 months after CCRT (6m-post-CCRT) G1-4 lymphopenia (P=0.001), and TLC nadir (P=0.020) were significantly associated with poorer OS. Multivariable analysis suggested that 6m-post-CCRT G1-4 lymphopenia (HR 2.614; P=0.041) were one of the independent predictors of OS. Further analysis inferred that radiation dose (OR: 1.328; P=0.005), GTV volume (OR: 1.004; P=0.036), and baseline TLC (OR: 0.288; P=0.001) were associated with 6m-post-CCRT lymphopenia.

Conclusion

The persistent lymphopenia at 6 months after CCRT was an independent prognostic factor of OS in LA-NSCLC patients. Higher radiation dose, larger gross tumor volume and lower baseline TLC were significantly related to 6m-post-CCRT lymphopenia.

Potential Molecular Mechanisms behind the Ultra-High Dose Rate "FLASH" Effect

FLASH radiotherapy, or the delivery of a dose at an ultra-high dose rate (>40 Gy/s), has recently emerged as a promising tool to enhance the therapeutic index in cancer treatment. The remarkable sparing of normal tissues and equivalent tumor control by FLASH irradiation compared to conventional dose rate irradiation—the FLASH effect—has already been demonstrated in several preclinical models and even in a first patient with T-cell cutaneous lymphoma. However, the biological mechanisms responsible for the differential effect produced by FLASH irradiation in normal and cancer cells remain to be elucidated. This is of great importance because a good understanding of the underlying radiobiological mechanisms and characterization of the specific beam parameters is required for a successful clinical translation of FLASH radiotherapy. In this review, we summarize the FLASH investigations performed so far and critically evaluate the current hypotheses explaining the FLASH effect, including oxygen depletion, the production of reactive oxygen species, and an altered immune response. We also propose a new theory that assumes an important role of mitochondria in mediating the normal tissue and tumor response to FLASH dose rates.

Mechanisms of FLASH effect

FLASH radiotherapy (FLASH-RT) is a novel radiotherapy technology defined as ultra-high dose rate (≥ 40 Gy/s) radiotherapy. The biological effects of FLASH-RT include two aspects: first, compared with conventional dose rate radiotherapy, FLASH-RT can reduce radiation-induced damage in healthy tissue, and second, FLASH-RT can retain antitumor effectiveness. Current research shows that mechanisms of the biological effects of FLASH-RT are related to oxygen. However, due to the short time of FLASH-RT, evidences related to the mechanisms are indirect, and the exact mechanisms of the biological effects of FLASH-RT are not completely clear and some are even contradictory. This review focuses on the mechanisms of the biological effects of FLASH-RT and proposes future research directions.

A machine learning model for grade 4 lymphopenia prediction during pelvic radiotherapy in patients with cervical cancer

Background/purpose

Severe lymphopenia during pelvic radiotherapy (RT) predicts poor survival in patients with cervical cancer. However, the risk of severe lymphopenia has not been well predicted. We developed a machine learning model using clinical and dosimetric information to predict grade 4 (G4) lymphopenia during pelvic RT in patients with cervical cancer.

Methods

This retrospective study included cervical cancer patients treated with definitive pelvic RT ± induction/concurrent chemotherapy. Clinical information and a set of dosimetric parameters of external beam radiotherapy plan were collected. G4 lymphopenia during RT, which was also referred to as G4 absolute lymphocyte count (ALC) nadir, was defined as ALC nadir <0.2 × 10⁹ cells/L during RT according to Common Terminology Criteria for Adverse Events (CTCAE) v4.03. Elastic-net logistic regression models were constructed for the prediction of G4 lymphopenia during pelvic RT using a repeated cross-validation methodology.

Results

A total of 130 patients were eligible, and 43 (33.1%) patients had G4 lymphopenia during RT. On multivariable analysis, G4 ALC nadir was associated with poor overall survival (OS) [hazard ratio (HR), 3.91; 95% confidence interval (CI), 1.34–11.38, p = 0.01]. Seven significant factors [Eastern Cooperative Oncology Group (ECOG) performance score, pre-RT hemoglobin, pre-RT lymphocytes, concurrent chemotherapy, gross tumor volume of regional lymphadenopathy (GTV_N volume), body volume, and maximum dose of planning target volume receiving at least 55 Gy (PTV_5500 Dmax)] were obtained by elastic-net logistic regression models and were included in the final prediction model for G4 ALC nadir. The model’s predicting ability in test set was area under the curve (AUC) = 0.77 and accuracy = 0.76. A nomogram of the final predicting model was constructed.

Conclusions

This study developed and validated a comprehensive model integrating clinical and dosimetric parameters by machine learning method, which performed well in predicting G4 lymphopenia during pelvic RT for cervical cancer and will facilitate physicians to identify patients at high risk of G4 lymphopenia who might benefit from modified treatment approaches.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

A Systematic Review and Meta-analysis of the Impact of Radiation-Related Lymphopenia on Outcomes in High-Grade Gliomas

Supriya MallickIntroduction  Malignant gliomas are the most common primary malignant brain tumors and are typically treated with maximal safe surgical resection followed by chemoradiation. One of the unintended effects of radiation is depletion of circulating lymphocyte pool, which has been correlated with inferior overall survival outcomes. Methods  A comprehensive and systematic searches of the PubMed, Cochrane Central, and Embase databases were done to assess the studies that have reported radiation-related lymphopenia in high-grade gliomas. Hazard ratios (HRs), odds ratios (OR), and mean differences were represented with Forest plots comparing patients with severe lymphopenia and no severe lymphopenia. Review Manager Version 5.3 (The Nordic Cochrane Centre, Copenhagen, Denmark) was used for the analysis. Results  Nineteen studies were included in the final systematic review and 12 studies were included in the meta-analysis. The odds of developing severe lymphopenia were 0.39 (95% CI:0.19, 0.81, I ²  = 94%, p  = 0.01). Patients with severe lymphopenia were at increased risk of death with a pooled HR = 2.19 (95% CI: 1.70, 2.83, I ²  = 0%, p <0.00001) compared to patients with no severe lymphopenia. The mean difference in survival between patients with severe lymphopenia and no severe lymphopenia was -6.72 months (95% CI: -8.95, -4.49, I ²  = 99%, p <0.00001), with a better mean survival in the no severe lymphopenia group. Conclusion  Radiation-induced severe lymphopenia was associated with poor overall survival and increased risk of death. Photon therapy, larger planning target volume, higher brain dose, higher hypothalamus dose, and female gender were associated with increased risk of severe lymphopenia.

Hematological abnormalities before and after initiation of cancer treatment among breast cancer patients attending at the University of Gondar comprehensive specialized hospital cancer treatment center

BACKGROUND

Breast cancer is the most frequent and fatal cancer type globally. The fatality rate of breast cancer is mostly due to disease complications like hematological alterations. Therefore, this study aimed to assess the hematological abnormalities before, during, and after the initiation of cancer treatment in breast cancer patients at the University of Gondar comprehensive specialized hospital.

METHODOLOGY

Hematological profiles were collected from 267 breast cancer patients who attended the cancer treatment center from September 2017 to August 2021. A data extraction sheet was used to extract data from the patient's medical chart, including sociodemography, clinical, and hematological profiles. EPI info version 3.5.1 and SPSS Version 25 softwares were used for data entrance and analysis, respectively. Descriptive statistics were summarized using frequency and percentage. The Friedman test followed by a Wilcoxon signed rank test was used to compare the mean difference between the hematological profiles at zero and after the 4th and 8th cycles of treatment.

RESULT

Of the total participants, 91% were females, and the median age of the study participants was 45 (IQR = 36, 55) years. Red blood cell, white blood cell, and lymphocyte counts, as well as hematocrit and hemoglobin values, were significantly reduced after the initiation of cancer treatment, while the platelet count and red cell distribution width were significantly increased. The prevalence of anemia was 21.7% (95% CI: 16.6, 26.8), 22.7% (95% CI: 17.6, 27.8), and 26.4% (95% CI: 21.3, 31.5) before, during, and after the initiation of cancer treatment, respectively. The prevalence of leukopenia before, during, and after treatment was 9.7%, 18.8%, and 15.1%, respectively. Finally the prevalence of thrombocytopenia was 6.3%, 3.4%, and 8% at before, during, and after treatment, respectively.

CONCLUSION

This study concluded that many hematological parameters were significantly affected by the breast cancer treatment. Therefore, proper patient follow-up and provide appropriate interventions related to their hematological abnormalities is crucial. It is also important to conduct further prospective studies to confirm the findings of this study.

Enhancement of antitumor immune response by radiation therapy combined with dual immune checkpoint inhibitor in a metastatic model of HER2-positive murine tumor

PURPOSE

Treatments for metastatic human epidermal growth factor receptor 2 (HER2)-positive tumors are improving but remain inadequate. We investigated activating antitumor immune response by combining radiation therapy with immune checkpoint inhibitors using mouse tumors overexpressing HER2, a pivotal driver oncogenic antigen, to develop new immunotherapies for metastatic HER2-positive tumors.

MATERIALS AND METHODS

NT2.5 cells were inoculated into the two mammary fat pads of FVB/N mice, which were divided into four groups: no treatment (Non), anti-PD-1 and anti-CTLA4 antibodies (P1C4), irradiation of the large tumor (Rad), and combination (R + P1C4) groups. Tumor growth, immunostaining of tumor-infiltrating lymphocytes, and the proportion of HER2-tumor antigen-specific CD8-positive T cells in the spleen and tumor-infiltrating lymphocytes were analyzed.

RESULTS

In the Rad group, unirradiated and irradiated tumors shrank after treatment. Besides the directly irradiated tumors, the unirradiated tumors in the R + P1C4 group shrank the most. In the unirradiated tumors, CD8-positive T cells and FOXP3-positive T cells accumulated significantly more in the R + P1C4 group than in the P1C4 and the Rad groups (all p < 0.001). CD4-positive helper T cells accumulated significantly more in the R + P1C4 group than in the Rad group (p < 0.05), but this was not significantly different from the P1C4 group. HER2-specific CD8-positive T cells in the spleen and tumor-infiltrating lymphocytes were significantly increased in the R + P1C4 group compared to the P1C4 and Rad groups (all p < 0.0001).

CONCLUSION

Irradiation of HER2-positive tumors induced an antitumor immune effect against the unirradiated tumor, which was enhanced by the combined use of immune checkpoint inhibitors and was mediated by enhanced recruitment of HER2-tumor antigen-specific cytotoxic T lymphocytes at the tumor site in an HER2-positive mouse tumor model. Harnessing the distant antitumor immune response induced by the combination of radiation therapy and immune checkpoint inhibitors could be a promising treatment strategy for metastatic HER2-positive tumors.

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.

Radioresistance of Non-Small Cell Lung Cancers and Therapeutic Perspectives

Survival in unresectable locally advanced stage non-small cell lung cancer (NSCLC) patients remains poor despite chemoradiotherapy. Recently, adjuvant immunotherapy improved survival for these patients but we are still far from curing most of the patients with only a 57% survival remaining at 3 years. This poor survival is due to the resistance to chemoradiotherapy, local relapses, and distant relapses. Several biological mechanisms have been found to be involved in the chemoradioresistance such as cancer stem cells, cancer mutation status, or the immune system. New drugs to overcome this radioresistance in NSCLCs have been investigated such as radiosensitizer treatments or immunotherapies. Different modalities of radiotherapy have also been investigated to improve efficacity such as dose escalation or proton irradiations. In this review, we focused on biological mechanisms such as the cancer stem cells, the cancer mutations, the antitumor immune response in the first part, then we explored some strategies to overcome this radioresistance in stage III NSCLCs with new drugs or radiotherapy modalities.

Lymphocyte dynamics during and after chemo-radiation correlate to dose and outcome in stage III NSCLC patients undergoing maintenance immunotherapy

PURPOSE

We investigated the dynamics of lymphocyte depletion and recovery during and after definitive concurrent chemoradiotherapy (CCRT), dose to which structures is correlated to them, and how they affect the prognosis of stage III non-small cell lung cancer (NSCLC) patients undergoing maintenance immunotherapy.

METHODS AND MATERIALS

In this retrospective study, absolute lymphocyte counts (ALC) of 66 patients were obtained before, during, and after CCRT. Persistent lymphopenia was defined as ALC < 500/μL at 3 months after CCRT. The impact of regional dose on lymphocyte depletion and recovery was investigated using voxel-based analysis (VBA).

RESULTS

Most patients (n = 65) experienced lymphopenia during CCRT: 39 patients (59.0%) had grade (G) 3+ lymphopenia. Fifty-nine patients (89.3%) recovered from treatment-related lymphopenia at 3 months after CCRT, whereas 7 (10.6%) showed persistent lymphopenia. Patient characteristics associated with persistent lymphopenia were older age and ALC before and during treatment. In multivariable Cox regression analysis, recovery from lymphopenia was identified as a significant prognostic factor for Progression Free Survival (HR 0.35, 95% CI 0.13-0.93, p = 0.034) and Overall Survival (HR 0.24, 95% CI 0.08-0.68, p = 0.007). Voxel-based analysis showed strong correlation of dose to the upper mediastinum with lymphopenia at the end of CCRT, but not at 3 months after CCRT.

CONCLUSION

Recovery from lymphopenia is strongly correlated to improved survival of patients undergoing CCRT and adjuvant immunotherapy, and is correlated to lymphocyte counts pre- and post-CCRT. VBA reveals high correlation of dose to large vessels to lymphopenia at the end of CCRT. Therefore, efforts should be made not only for preventing lymphocyte depletion during CCRT but also for helping lymphocyte recovery after CCRT.

A hybrid deep learning model for forecasting lymphocyte depletion during radiation therapy

PURPOSE

Recent studies have shown that severe depletion of the absolute lymphocyte count (ALC) induced by radiation therapy (RT) has been associated with poor overall survival of patients with many solid tumors. In this paper, we aimed to predict radiation-induced lymphocyte depletion in esophageal cancer patients during the course of RT based on patient characteristics and dosimetric features.

METHODS

We proposed a hybrid deep learning model in a stacked structure to predict a trend toward ALC depletion based on the clinical information before or at the early stages of RT treatment. The proposed model consisted of four channels, one channel based on long short-term memory (LSTM) network and three channels based on neural networks, to process four categories of features followed by a dense layer to integrate the outputs of four channels and predict the weekly ALC values. Moreover, a discriminative kernel was developed to extract temporal features and assign different weights to each part of the input sequence which enabled the model to focus on the most relevant parts. The proposed model was trained and tested on a dataset of 860 esophageal cancer patients who received concurrent chemoradiotherapy.

RESULTS

The performance of the proposed model was evaluated based on several important prediction metrics and compared to other commonly used prediction models. The results showed that the proposed model outperformed off-the-shelf prediction methods with at least a 30% reduction in the mean squared error (MSE) of weekly ALC predictions based on pretreatment data.Moreover, using an extended model based on augmented first-week treatment data reduced the MSE of predictions by 70% compared to the model based on the pretreatment data.

CONCLUSIONS

In conclusion, our model performed well in predicting radiation-induced lymphocyte depletion for RT treatment planning. The ability to predict ALC will enable physicians to evaluate individual RT treatment plans for lymphopenia risk and to identify patients at high risk who would benefit from modified treatment approaches. This article is protected by copyright. All rights reserved.

Impact of hematologic toxicities during concurrent chemoradiation for cervical cancer

Objective

To evaluate the prognostic significance of hematological toxicities during cervical cancer treatment.

Methods

Patients treated for cervical carcinoma with definitive chemoradiation were identified. Toxicities were assessed during weeks 1 to 6 of concurrent external beam radiation and chemotherapy. Outcomes were analyzed using Cox regression analysis.

Results

One hundred twenty-one patients with Federation of Gynecology and Obstetrics stage I–III disease were eligible for analysis. Median age at diagnosis was 45 years (interquartile range, 40–52) with median follow-up time of 34 months (95% confidence interval, 30.8–37.2). All patients experienced some grade of hematologic toxicity. The most common grade 3+ toxicities were low absolute lymphocyte count (n=115, 95%), low white blood cell count (n=21, 17%), and anemia (n=11, 9%). The most common grade 4 toxicity was lymphopenia, experienced by 36% of patients (n=44). Grade 4 lymphopenia was associated with reduced overall survival (hazard ratio [HR], 4.5; P=0.005), progression-free survival (HR, 3.4; P=0.001), and local control (HR, 4.1; P=0.047). Anemia grade 3, 4 was also associated with reduced overall survival (HR, 4.1; P=0.014). After controlling for disease and treatment variables, grade 4 lymphopenia remained significantly associated with reduced overall survival (HR, 9.85; P=0.007). The association with grade 4 lymphopenia only remained significant in women of Hispanic ethnicity.

Conclusion

Severe lymphopenia was associated with reduced overall survival and progression-free survival in Hispanic women undergoing definitive chemoradiation for cervical cancer, but not associated with outcomes in non-Hispanic women.

A dynamic blood flow model to compute absorbed dose to circulating blood and lymphocytes in liver external beam radiotherapy

We have developed a novel 4D dynamic liver blood flow model, capable of accurate dose estimation to circulating blood cells during liver-directed external beam radiotherapy, accounting for blood recirculation and radiation delivery time structure. Adult male and adult female liver computational phantoms with detailed vascular trees were developed to include the hepatic arterial, hepatic portal venous, and hepatic venous trees. A discrete time Markov Chain approach was applied to determine the spatiotemporal distribution of 10⁵blood particles (BP) in the human body based on reference values for cardiac output and organ blood volumes. For BPs entering the liver, an explicit Monte Carlo simulation was implemented to track their propagation along ∼2000 distinct vascular pathways through the liver. The model tracks accumulated absorbed dose from time-dependent radiation fields with a 0.1 s time resolution. The computational model was then evaluated for 3 male and 3 female patients receiving photon (VMAT and IMRT) and proton (passive SOBP and active PBS) treatments. The dosimetric impact of treatment modality, delivery time, and fractionation on circulating blood cells was investigated and quantified using the mean dose (μdose,b),V_>0Gy,V_>0.125Gy,andD_2%. Average reductions inμdose,b,V_>0Gy,V_>0.125GyandD_2%of 45%, 6%, 53%, 19% respectively, were observed for proton treatments as compared to photon treatments. Our simulation also showed thatV_>0Gy,V_>0.125Gy, andD_2%were highly sensitive to the beam-on time. BothV_>0GyandV_>0.125Gyincreased with beam-on time, whereasD_2%decreased with increasing beam-on time, demonstrating the tradeoff between low dose to a large fraction of blood cells and high dose to a small fraction of blood cells. Consequently, proton treatments are not necessarily advantageous in terms of dose to the blood simply based on integral dose considerations. Instead, both integral dose and beam-on time can substantially impact relevant dosimetric indices.

Effect of systemic inflammation biomarkers on overall survival after lung cancer radiotherapy: a single-center large-cohort study

INTRODUCTION

Recent studies suggest that immune-related cells can be recruited for anti-tumor functions as well as tumor progression and the interplay between systemic inflammation and local immune response may play a major role in the development and progression of various cancers including lung cancer. Inflammatory markers, such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) can be used as surrogate biomarkers of host immune status. In this work, associations between neutrophils, lymphocytes, platelets, NLR, PLR, SII and overall survival (OS) are investigated in two cohorts of non-small cell lung cancer (NSCLC) patients treated with fractionated radiotherapy (RT) and stereotactic body radiation therapy (SBRT) and a cohort of small cell lung cancer (SCLC) patients treated with fractionated RT.

MATERIAL AND METHODS

Data from 2513 lung cancer patients were retrospectively analyzed. Baseline NLR, PLR, and SII (NLR × platelet count) were calculated from full blood test prior to RT initiation. Cox proportional hazards regression analyses were used to evaluate the association between systemic inflammation markers and known clinical factors with OS.

RESULTS

The two-year OS was 42%, 63%, and 62% in the NSCLC fractionated RT, SBRT, and SCLC cohort. NLR (per 1 unit: hazard ratio [HR]: 1.04, p < 0.05) and SII (per 100 × 109/L: HR: 1.01, p < 0.05) remained the strongest independent factors of OS in multivariable Cox analyses, correcting for clinical factors in early-stage and locally advanced NSCLC and SCLC patients treated with RT.

DISCUSSION

This single-center large-cohort study suggests that baseline NLR and SII are independent prognostic biomarkers associated with OS in locally advanced and early-stage NSCLC patients treated with either curative-intent fractionated RT or SBRT and SCLC patients treated with curative-intent fractionated RT. External validation is warranted to evaluate the utility of these biomarkers for patients' stratification and adapting new treatment approaches.

Early onset of severe lymphopenia during definitive radiotherapy correlates with mean body dose and predicts poor survival in cervical cancer

BACKGROUND:

Lymphopenia during definitive radiotherapy (RT) has been shown to reduce survival in patients with cervical cancer. However, there are few studies on the significance of onset time of lymphopenia during RT in patients with cervical cancer.

OBJECTIVE:

This study aimed to exam the prognostic significance of early onset of severe lymphopenia (EOSL) during definitive RT in patients with cervical cancer.

METHODS:

Newly diagnosed cervical cancer patients treated with definitive RT from January 2015 to December 2019 were eligible for this retrospective study. EOSL was defined as first onset of grade 3–4 lymphopenia ⩽ 3 weeks from the start of RT. Mean body dose (MBD) was the mean radiation dose absorbed by the body during the whole course of external beam RT (EBRT) and was directly obtained from the dose volume histogram (DVH) of the EBRT planning. Logistic regression analysis and restricted cubic spline (RCS) models were applied to assess relationships between clinicopathological factors and EOSL. Survival analysis was performed using Kaplan-Meier curves and log-rank test. A COX regression model was developed to predict overall survival (OS).

RESULTS:

A total of 104 patients were included and 59.6% had EOSL. MBD (P= 0.04), concurrent cisplatin (P= 0.011), and pre-RT absolute lymphocyte count (ALC) (P= 0.001) were associated with EOSL. A linear relationship (P for non-linearity = 0.803) between MBD and risk of EOSL was found. Patients with EOSL had decreased OS (2-yr 75.1% vs 91.1%, P= 0.021) and progression-free survival (PFS) (2-yr 71.2% vs 83.7%, P= 0.071). An OS prediction COX model was developed with C-index of 0.835 and AUC of 0.872.

CONCLUSIONS:

EOSL during definitive RT correlates with MBD and predicts poor survival in patients with cervical cancer.

Long-acting recombinant human interleukin-7, NT-I7, increases cytotoxic CD8+ T cells and enhances survival in mouse glioma models

PURPOSE

Patients with glioblastoma (GBM) are treated with radiation therapy (RT) and temozolomide (TMZ). These treatments may cause prolonged systemic lymphopenia, which itself is associated with poor outcomes. NT-I7 is a long-acting IL-7 that expands CD4 and CD8 T cell numbers in humans and mice. We tested whether NT-I7 prevents systemic lymphopenia and improves survival in mouse models of GBM.

EXPERIMENTAL DESIGN

C57BL/6 mice bearing intracranial tumors (GL261 or CT2A) were treated with RT (1.8 Gy/day x 5 days), TMZ (33 mg/kg/day x 5 days), and/or NT-I7 (10 mg/kg on the final day of RT). We followed the mice for survival while serially analyzing levels of circulating T lymphocytes. We assessed regulatory T cells (Treg) and cytotoxic T lymphocytes in the tumor microenvironment, cervical lymph nodes, spleen, and thymus; and hematopoietic stem and progenitor cells (HSPCs) in the bone marrow.

RESULTS

GBM tumor-bearing mice treated with RT+NT-I7 increased T lymphocytes in the lymph nodes, thymus, and spleen, enhanced IFNγ production, and decreased T_reg cells in the tumor which was associated with a significant increase in survival. NT-I7 also enhanced central memory and effector memory CD8 T cells in lymphoid organs and tumor. Depleting CD8 T cells abrogated the effects of NT-I7. Furthermore, NT-I7 treatment decreased progenitor cells in the bone marrow.

CONCLUSION

In orthotopic glioma-bearing mice, NT-I7 mitigates radiation-related lymphopenia, increases cytotoxic CD8 T lymphocytes systemically and in the tumor, and improves survival. A phase I/II trial to evaluate NT-I7 in patients with high-grade gliomas is ongoing (NCT03687957).

Taxane/gemcitabine-containing chemotherapy plus locoregional IMRT for patients with de novo metastatic nasopharyngeal carcinoma: the treatment outcomes and prognostic factors analysis

Purpose

To evaluate treatment outcomes of de novo metastatic nasopharyngeal carcinoma (mNPC) patients receiving taxane/gemcitabine-containing chemotherapy followed by locoregional intensity-modulated radiotherapy (IMRT) and analyze potential prognostic factors.

Methods

A total of 118 patients between March 2008 and November 2018 were retrospectively analyzed. All the patients were treated with taxane/gemcitabine-containing systemic chemotherapy followed by definitive locoregional IMRT. Potential prognostic factors including baseline absolute lymphocyte count (ALC) and the subdivision of metastasis were analyzed.

Results

The median follow-up time for the whole group was 31.5 months (range 5–138 months). Of the 118 patients, 9 (7.6%) patients experienced local regional failure and 60 (50.8%) patients had progression of distant metastasis. At the time of the last follow-up, 61 (51.7%) patients were dead. The 5-year actuarial progression free survival (PFS), overall survival (OS),distant metastasis relapse free survival (DMFS) and local regional recurrence free survival (LRFS) were 34.2%, 44%, 41.1% and 82.6%, respectively. Baseline lymphocyte count ≥ 1600/μl prior to the treatment conferred better locoregional control (5y-LRFS 96% vs. 64.7%, p < 0.001) and distant metastasis control (5y-MFS 50.4% vs. 32.4%, p = 0.023). The multivariate analysis showed that high lymphocyte count was the most relevant predictor of superior PFS (HR = 0.236, p < 0.001) and OS (HR = 0.518, p = 0.04). M subdivision was found as another independent prognostic factor for OS but not for PFS.

Conclusion

Taxane/gemcitabine-containing chemotherapy combined with IMRT represents an effective treatment modality for mNPC. Baseline ALC is an independent significant prognostic factor for PFS and OS.

Radiation-induced immune response in novel radiotherapy approaches FLASH and spatially fractionated radiotherapies

The last several years have revealed increasing evidence of the immunomodulatory role of radiation therapy. Radiotherapy reshapes the tumoral microenvironment can shift the balance toward a more immunostimulatory or immunosuppressive microenvironment. The immune response to radiation therapy appears to depend on the irradiation configuration (dose, particle, fractionation) and delivery modes (dose rate, spatial distributions). Although an optimal irradiation configuration (dose, temporal fractionation, spatial dose distribution, etc.) has not yet been determined, temporal schemes employing high doses per fraction appear to favor radiation-induced immune response through immunogenic cell death. Through the release of damage-associated molecular patterns and the sensing of double-stranded DNA and RNA breaks, immunogenic cell death activates the innate and adaptive immune response, leading to tumor infiltration by effector T cells and the abscopal effect. Novel radiotherapy approaches such as FLASH and spatially fractionated radiotherapies (SFRT) strongly modulate the dose delivery method. FLASH-RT and SFRT have the potential to trigger the immune system effectively while preserving healthy surrounding tissues. This manuscript reviews the current state of knowledge on the immunomodulation effects of these two new radiotherapy techniques in the tumor, healthy immune cells and non-targeted regions, as well as their therapeutic potential in combination with immunotherapy.

Vertebral body and splenic irradiation are associated with lymphopenia in localized pancreatic cancer treated with stereotactic body radiation therapy

OBJECTIVES

The purpose of this study was to determine if vertebral body and splenic dosimetry was associated with the development of lymphopenia in patients with borderline resectable (BRPC) and locally advanced pancreatic cancer (LAPC) treated with stereotactic body radiation therapy (SBRT).

METHODS

Patients with BRPC/LAPC who were treated with SBRT and who had lymphocyte counts and radiation treatment plans available for review were included in the study. Vertebral body levels T11-L3 and the spleen were retrospectively contoured for each patient. Univariate (UVA) and multivariable analyses (MVA) were performed to identify associations between vertebral body and splenic dosimetric parameters with absolute lymphocyte count (ALC) and grade ≥ 2 lymphopenia. Receiver operator characteristic curves were generated to identify dose-volume thresholds in predicting grade ≥ 2 lymphopenia.

RESULTS

A total of 132 patients were included in the study. On UVA and MVA, vertebral V15 (regression coefficient [β]: - 0.026, 95% CI - 0.044 to - 0.009, p = 0.003), vertebral V2.5 (β: - 0.011, 95% CI - 0.020 to - 0.002, p = 0.015), and log10PTV (β: - 0.15, 95% CI - 0.30 to - 0.005, p = 0.042) were associated with post-SBRT ALC. On UVA and MVA, vertebral V15 (odds ratio [OR]: 3.98, 95% CI 1.09-14.51, p = 0.027), vertebral V2.5 (OR: 1.04, 95% CI 1.00-1.09, p = 0.032), and spleen V10 (OR: 1.05, 95% CI 1.09-1.95, p = 0.004) were associated with development of grade ≥ 2 lymphopenia. Development of grade ≥ 2 lymphopenia was more likely in patients with vertebral V15 ≥ 5.84% (65.5% vs 34.0%, p = 0.002), vertebral V2.5 ≥ 48.36% (48.9% vs 23.8%, p = 0.005), and spleen V10 ≥ 4.17% (56.2% vs 26.9%, p < 0.001).

CONCLUSIONS

Increasing radiation dose to vertebral bodies and spleen were associated with the development of lymphopenia in BRPC/LAPC treated with SBRT. Optimization of vertebral body and splenic dosimetry may reduce the risk of developing lymphopenia and improve clinical outcomes in this population.

Relationship between biodosimetric parameters and treatment volumes in three types of prostate radiotherapy

Brachytherapy (BT) and external beam radiotherapy (EBRT) apply different dose rates, overall treatment times, energies and fractionation. However, the overall impact of these variables on the biological dose of blood is neglected. As the size of the irradiated volume influences the biological effect as well, we studied chromosome aberrations (CAs) as biodosimetric parameters, and explored the relationship of isodose surface volumes (ISVs: V_1%, V_1Gy, V_10%, V_10Gy, V_100%, V_150%) and CAs of both irradiation modalities. We performed extended dicentrics assay of lymphocytes from 102 prostate radiotherapy patients three-monthly for a year. Aberration frequency was the highest after EBRT treatment. It increased after the therapy and did not decrease significantly during the first follow-up year. We showed that various types of CAs 9 months after LDR BT, 3 months after HDR BT and in a long time-range (even up to 1 year) after EBRT positively correlated with ISVs. Regression analysis confirmed these relationships in the case of HDR BT and EBRT. The observed differences in the time points and aberration types are discussed. The ISVs irradiated by EBRT showed stronger correlation and regression relationships with CAs than the ISVs of brachytherapy.

Higher Radiation Dose to the Immune Cells Correlates with Worse Tumor Control and Overall Survival in Patients with Stage III NSCLC: A Secondary Analysis of RTOG0617

Background: We hypothesized that the Effective radiation Dose to the Immune Cells (EDIC) in circulating blood is a significant factor for the treatment outcome in patients with locally advanced non-small-cell lung cancer (NSCLC). Methods: This is a secondary study of a phase III trial, NRG/RTOG 0617, in patients with stage III NSCLC treated with radiation-based treatment. The EDIC was computed as equivalent uniform dose to the entire blood based on radiation doses to all blood-containing organs, with consideration of blood flow and fractionation effect. The primary endpoint was overall survival (OS), and the secondary endpoints were progression-free survival (PFS) and local progression-free survival (LPFS). The EDIC-survival relationship was analyzed with consideration of clinical significant factors. Results: A total of 456 patients were eligible. The median EDIC values were 5.6 Gy (range, 2.1-12.2 Gy) and 6.3 Gy (2.1-11.6 Gy) for the low- and high-dose groups, respectively. The EDIC was significantly associated with OS (hazard ratio [HR] = 1.12, p = 0.005) and LPFS (HR = 1.09, p = 0.02) but PFS (HR = 1.05, p = 0.17) after adjustment for tumor dose, gross tumor volume and other factors. OS decreased with an increasing EDIC in a non-linear pattern: the two-year OS decreased first with a slope of 8%/Gy when the EDIC < 6 Gy, remained relatively unchanged when the EDIC was 6-8 Gy, and followed by a further reduction with a slope of 12%/Gy when the EDIC > 8 Gy. Conclusions: The EDIC is a significant independent risk factor for poor OS and LPFS in RTOG 0617 patients with stage III NSCLC, suggesting that radiation dose to circulating immune cells is critical for tumor control. Organ at risk for the immune system should be considered during RT plan.