The association between total lymphocyte count after concomitant chemoradiation and overall survival in patients with newly diagnosed glioblastoma

Flow cytometry detection and quantification of circulating leukocyte subpopulations in mice after brain irradiation

In the context of high-grade gliomas such as glioblastoma (GBM), the immune part of the tumor microenvironment (TME) is involved in tumor growth and tumor recurrence. It is mostly represented by high amount of macrophages and low amount of lymphocytes. GBM in itself as well as x-ray-based radiotherapy, a standard treatment for brain tumors, are also associated with systemic effects like lymphopenia that correlates with a poor prognosis. This contributes to the immune-suppressive nature of the TME and may explain the lack of the anti-tumor immune response. Radiation-induced lymphopenia (RIL) is generally evaluated on CD4+ and CD8+ count or on a CBC (complete blood count), but the heterogeneity of the subtypes prompts us to explore them in detail to better understand the cellular response to brain irradiation. To facilitate and develop the evaluation of x-ray brain exposure on circulating immune cells, we developed a reproducible and reliable method to quantify the variation of lymphoid and myeloid subtypes using flow cytometry after brain irradiation in the rodent.

From lymphopenia to restoration: IL-7 immunotherapy for lymphocyte recovery in glioblastoma

Glioblastoma, the most prevalent malignant primary brain tumor, presents substantial treatment challenges because of its inherent aggressiveness and limited therapeutic options. Lymphopenia, defined as reduced peripheral blood lymphocyte count, commonly occurs as a consequence of the disease and its treatment. Recent studies have associated lymphopenia with a poor prognosis. Factors that contribute to lymphopenia include radiotherapy, chemotherapy, and the tumor itself. Patients who are female, older, using dexamethasone, or receiving higher doses of radiation therapy are particularly vulnerable to this condition. Several preclinical studies have explored the use of interleukin-7, a crucial cytokine for lymphocyte homeostasis, to restore lymphocyte counts and potentially rebuild the immune system to combat glioblastoma cells. With the development of recombinant interleukin-7 for prolonged activity in the body, various clinical trials are underway to explore this treatment in patients with glioblastoma. Our study provides a comprehensive summary of the incidence of lymphopenia, its potential biological background, and the associated clinical risk factors. Furthermore, we reviewed several clinical trials using IL-7 cytokine therapy in glioblastoma patients. We propose IL-7 as a promising immunotherapeutic strategy for glioblastoma treatment. We are optimistic that our study will enhance understanding of the complex interplay between lymphopenia and glioblastoma and will pave the way for the development of more effective treatment modalities.

Systematic review and pooled analysis of the impact of treatment-induced lymphopenia on survival of glioblastoma patients

PURPOSE/OBJECTIVE(S)

Treatment related lymphopenia is a known toxicity for glioblastoma (GBM) patients and several single-institution studies have linked lymphopenia with poor survival outcomes. We performed a systematic review and pooled analysis to evaluate the association between lymphopenia and overall survival (OS) for GBM patients undergoing chemotherapy and radiation therapy (RT).

MATERIALS/METHODS

Following PRISMA guidelines, a systematic literature review of the MEDLINE database and abstracts from ASTRO, ASCO, and SNO annual meetings was conducted. A pooled analysis was performed using inverse variance-weighted random effects to generate a pooled estimate of the hazard ratio of association between lymphopenia and OS.

RESULTS

Ten of 104 identified studies met inclusion criteria, representing 1,718 patients. The lymphopenia cutoff value varied (400-1100 cells/uL) and as well as the timing of its onset. Studies were grouped as time-point (i.e., lymphopenia at approximately 2-months post-RT) or time-range (any lymphopenia occurrence from treatment-start to approximately 2-months post-RT. The mean overall pooled incidence of lymphopenia for all studies was 31.8%, and 11.8% vs. 39.9% for time-point vs. time-range studies, respectively. Lymphopenia was associated with increased risk of death, with a pooled HR of 1.78 (95% CI 1.46-2.17, P < 0.00001) for the time-point studies, and a pooled HR of 1.38 (95% CI 1.24-1.55, P < 0.00001) for the time-point studies. There was no significant heterogeneity between studies.

CONCLUSION

These results strengthen observations from previous individual single-institution studies and better defines the magnitude of the association between lymphopenia with OS in GBM patients, highlighting lymphopenia as a poor prognostic factor.

The need for paradigm shift: prognostic significance and implications of standard therapy-related systemic immunosuppression in glioblastoma for immunotherapy and oncolytic virotherapy

Despite significant advances in our knowledge regarding the genetics and molecular biology of gliomas over the past two decades and hundreds of clinical trials, no effective therapeutic approach has been identified for adult patients with newly diagnosed glioblastoma, and overall survival remains dismal. Great hopes are now placed on combination immunotherapy. In clinical trials, immunotherapeutics are generally tested after standard therapy (radiation, temozolomide, and steroid dexamethasone) or concurrently with temozolomide and/or steroids. Only a minor subset of patients with progressive/recurrent glioblastoma have benefited from immunotherapies. In this review, we comprehensively discuss standard therapy-related systemic immunosuppression and lymphopenia, their prognostic significance, and the implications for immunotherapy/oncolytic virotherapy. The effectiveness of immunotherapy and oncolytic virotherapy (viro-immunotherapy) critically depends on the activity of the host immune cells. The absolute counts, ratios, and functional states of different circulating and tumor-infiltrating immune cell subsets determine the net immune fitness of patients with cancer and may have various effects on tumor progression, therapeutic response, and survival outcomes. Although different immunosuppressive mechanisms operate in patients with glioblastoma/gliomas at presentation, the immunological competence of patients may be significantly compromised by standard therapy, exacerbating tumor-related systemic immunosuppression. Standard therapy affects diverse immune cell subsets, including dendritic, CD4+, CD8+, natural killer (NK), NKT, macrophage, neutrophil, and myeloid-derived suppressor cell (MDSC). Systemic immunosuppression and lymphopenia limit the immune system's ability to target glioblastoma. Changes in the standard therapy are required to increase the success of immunotherapies. Steroid use, high neutrophil-to-lymphocyte ratio (NLR), and low post-treatment total lymphocyte count (TLC) are significant prognostic factors for shorter survival in patients with glioblastoma in retrospective studies; however, these clinically relevant variables are rarely reported and correlated with response and survival in immunotherapy studies (e.g., immune checkpoint inhibitors, vaccines, and oncolytic viruses). Our analysis should help in the development of a more rational clinical trial design and decision-making regarding the treatment to potentially improve the efficacy of immunotherapy or oncolytic virotherapy.

Human gamma-delta (γδ) T cell therapy for glioblastoma: A novel alternative to overcome challenges of adoptive immune cell therapy

Glioblastoma is the most common brain malignancy with devastating prognosis. Numerous clinical trials using various target therapeutic agents have failed and recent clinical trials using check point inhibitors also failed to provide survival benefits for glioblastoma patients. Adoptive T cell transfer is suggested as a novel therapeutic approach that has exhibited promise in preliminary clinical studies. However, the clinical outcomes are inconsistent, and there are several limitations of current adoptive T cell transfer strategies for glioblastoma treatment. As an alternative cell therapy, gamma-delta (γδ) T cells have been recently introduced for several cancers including glioblastoma. Since the leading role of γδ T cells is immune surveillance by recognizing a broad range of ligands including stress molecules, phosphoantigens, or lipid antigens, recent studies have suggested the potential benefits of γδ T cell transfer against glioblastomas. However, γδ T cells, as a small subset (1-5%) of T cells in human peripheral blood, are relatively unknown compared to conventional alpha-beta (αβ) T cells. In this context, our study introduced γδ T cells as an alternative and novel option to overcome several challenges regarding immune cell therapy in glioblastoma treatment. We described the unique characteristics and advantages of γδ T cells compared to conventional αβ T cells and summarize several recent preclinical studies using human gamma-delta T cell therapy for glioblastomas. Finally, we suggested future direction of human γδ T cell therapy for glioblastomas.

Impact of radiation on immune cells in patients with low-grade brain tumor: Identifying critical factors affecting lymphopenia and neutrophil-to-lymphocyte ratio

PURPOSE

Studies about the effect of radiation therapy (RT) on immune cells are usually limited to a high-grade glioma mostly exposed to chemotherapy and a high dose of steroid which also could affect immune cells. The purpose of this retrospective analysis of low-grade brain tumor patients treated by RT alone is to determine significant factors influencing neutrophil-to-lymphocyte ratio (NLR), absolute neutrophil counts (ANC), and absolute lymphocyte counts (ALC).

MATERIALS AND METHODS

A total of 41 patients who received RT between 2007 and 2020 were analyzed. Patients who received chemotherapy and high-dose of steroid were excluded. ANC and ALC were collected before starting RT (baseline) and within one-week before ending RT (post-treatment). Changes of ANC, ALC, and NLR between baseline and post-treatment were calculated.

RESULTS

ALC decreased in 32 patients (78.1%). NLR increased in 31 patients (75.6%). No patients developed grade 2 or higher hematologic toxicities. The decrease of ALC was significantly correlated with the dose to brain V15 in a simple and multiple linear regression (p = 0.043). Brain V10 and V20 adjacent to V15 were also marginally significant factors determining the reduction of lymphocytes (p = 0.050 and p = 0.059, respectively). However, it was difficult to find predictive factors affecting changes of ANC and NLR.

CONCLUSION

In low-grade brain tumor patients who are treated by RT alone, ALC decreased and NLR increased in three-fourth of patients, although the magnitude was minimal. The decrease of ALC was mainly affected by low dose to the brain. However, RT dose was not correlated with changes of ANC or NLR.

Proton versus photon radiation therapy: A clinical review

While proton radiation therapy offers substantially better dose distribution characteristics than photon radiation therapy in certain clinical applications, data demonstrating a quantifiable clinical advantage is still needed for many treatment sites. Unfortunately, the number of patients treated with proton radiation therapy is still comparatively small, in some part due to the lack of evidence of clear benefits over lower-cost photon-based treatments. This review is designed to present the comparative clinical outcomes between proton and photon therapies, and to provide an overview of the current state of knowledge regarding the effectiveness of proton radiation therapy.

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.

Enhancing anti-tumour innate immunity by targeting the DNA damage response and pattern recognition receptors in combination with radiotherapy

Radiotherapy is one of the most effective and frequently used treatments for a wide range of cancers. In addition to its direct anti-cancer cytotoxic effects, ionising radiation can augment the anti-tumour immune response by triggering pro-inflammatory signals, DNA damage-induced immunogenic cell death and innate immune activation. Anti-tumour innate immunity can result from recruitment and stimulation of dendritic cells (DCs) which leads to tumour-specific adaptive T-cell priming and immunostimulatory cell infiltration. Conversely, radiotherapy can also induce immunosuppressive and anti-inflammatory mediators that can confer radioresistance. Targeting the DNA damage response (DDR) concomitantly with radiotherapy is an attractive strategy for overcoming radioresistance, both by enhancing the radiosensitivity of tumour relative to normal tissues, and tipping the scales in favour of an immunostimulatory tumour microenvironment. This two-pronged approach exploits genomic instability to circumvent immune evasion, targeting both hallmarks of cancer. In this review, we describe targetable DDR proteins (PARP (poly[ADP-ribose] polymerase); ATM/ATR (ataxia-telangiectasia mutated and Rad3-related), DNA-PKcs (DNA-dependent protein kinase, catalytic subunit) and Wee1 (Wee1-like protein kinase) and their potential intersections with druggable immunomodulatory signalling pathways, including nucleic acid-sensing mechanisms (Toll-like receptors (TLR); cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) and retinoic acid-inducible gene-I (RIG-I)-like receptors), and how these might be exploited to enhance radiation therapy. We summarise current preclinical advances, recent and ongoing clinical trials and the challenges of therapeutic combinations with existing treatments such as immune checkpoint inhibitors.

PrACTiC: A Predictive Algorithm for Chemoradiotherapy-Induced Cytopenia in Glioblastoma Patients

Background

Chemotherapy-induced cytopenia is the most frequent side effect of chemoradiotherapy in glioblastoma patients which may lead to reduced delivery of treatment. This study aims to develop a predictive model that is able to forecast the cytopenia induced by temozolomide (TMZ) during concomitant chemoradiotherapy.

Methods

Medical records of 128 patients with newly diagnosed glioblastoma were evaluated to extract the baseline complete blood test before and during the six weeks of chemoradiotherapy to create a dataset for the development of ML models. Using the constructed dataset, different ML algorithms were trained and tested.

Results

Our proposed algorithm achieved accuracies of 85.6%, 88.7%, and 89.3% in predicting thrombocytopenia, lymphopenia, and neutropenia, respectively.

Conclusions

The algorithm designed and developed in this study, called PrACTiC, showed promising results in the accurate prediction of thrombocytopenia, neutropenia, and lymphopenia induced by TMZ in glioblastoma patients. PrACTiC can provide valuable insight for physicians and help them to make the necessary treatment modifications and prevent the toxicities.

Prognostic Value and Risk Factors of Treatment-Related Lymphopenia in Malignant Glioma Patients Treated With Chemoradiotherapy: A Systematic Review and Meta-Analysis

Background: Immunotherapy has shown promising therapeutic efficacy in various cancers but not gliomas. Circulating lymphocytes play critical roles in cancer control and responses to immune checkpoint inhibitors. Treatment-related lymphopenia has been associated with poor survival in patients with various tumors. This meta-analysis evaluated the risk and impact of lymphopenia in patients with glioma. Methods: The PubMed, Embase, Web of Science, and Cochrane Library databases were comprehensively searched. Eligible studies were included if they reported the incidence and risk factors of lymphopenia and the impact of lymphopenia on survival. Stata 16.0 was used for this meta-analysis. Results: A total of 21 studies were included in the final systematic review and 20 were included in the quantitative analysis. The overall incidence of grade III/IV lymphopenia was 31.6% [95% confidence interval (CI), 22.3-40.8%]. Pooled results based on pathology of glioma revealed that the incidence in astrocytoma and astrocytoma oligodendroglioma patients was 20.2% (95% CI:5.9-34.4%), and the incidence in glioblastoma patients was 27.6% (95% CI:16.2-38.9%). Lymphopenia was associated with poor overall survival (hazard ratio, 1.99; 95% CI, 1.74-2.27; P< 0.001) compared to no lymphopenia. Brain receiving radiation dose of 20 or 25 Gy, female sex, older age, lower baseline lymphocyte count, and dexamethasone dose > 2 mg instead of baseline use were risk factors for lymphopenia. Conclusions: Treatment-related lymphopenia was associated with decreased survival in patients with glioma. Optimization of chemoradiation regimens, particularly in patients with concurrent risk factors, can reduce lymphopenia and potentially improve survival in the era of immunotherapy.

The Influence of Severe Radiation-Induced Lymphopenia on Overall Survival in Solid Tumors: A Systematic Review and Meta-Analysis

PURPOSE

Emerging evidence suggests a detrimental prognostic association between radiation-induced lymphopenia (RIL) and pathologic response, progression-free survival, and overall survival (OS) in patients who undergo radiation therapy for cancer. The aim of this study was to systematically review and meta-analyze the prognostic impact of RIL on OS in patients with solid tumors.

METHODS AND MATERIALS

PubMed/MEDLINE and Embase were systematically searched. The analysis included intervention and prognostic studies that reported on the prognostic relationship between RIL and survival in patients with solid tumors. An overall pooled adjusted hazard ratio (aHR) was calculated using a random-effects model. Subgroup analyses for different patient-, tumor-, treatment-, and study-related characteristics were performed using meta-regression.

RESULTS

Pooling of 21 cohorts within 20 eligible studies demonstrated a statistically significant association between OS and grade ≥3 versus grade 0-2 RIL (n = 16; pooled aHR, 1.65; 95% confidence interval [CI], 1.43-1.90) and grade 4 RIL versus grade 0-3 (n = 5; aHR, 1.53; 95% CI, 1.24-1.90). Moderate heterogeneity among aHRs was observed, mostly attributable to overestimated aHRs in 7 studies likely subject to model-overfitting. Subgroup analysis showed significant prognostic impact of grade ≥3 RIL in 4 brain tumor (aHR, 1.63; 95% CI, 1.06-2.51), 4 lung cancer (aHR, 1.52; 95% CI, 1.01-2.29), and 3 pancreatic cancer (aHR, 1.92; 95% CI, 1.10-3.36) cohorts.

CONCLUSIONS

This meta-analysis demonstrates a significant detrimental prognostic association between grade ≥3 lymphopenia and OS in patients receiving radiation therapy for solid tumors. This finding appears consistent for tumors of the brain, thorax, and upper abdomen and provides an imperative to further elucidate the potential survival benefit of lymphopenia-mitigating strategies.

Lymphocyte to C-reactive protein ratio predicts long-term outcomes for patients with lower rectal cancer

BACKGROUNDS

The lymphocyte to C-reactive protein (CRP) ratio (LCR) is an indicator of systemic inflammation and host-tumor cell interactions. The aim of this study was to investigate the prognostic significance of LCR in lower rectal cancer patients who received preoperative chemo-radiotherapy (CRT).

METHODS

Forty-eight patients with lower rectal cancer who underwent CRT followed by curative surgery were enrolled in this study. Routine blood examinations were performed before and after CRT were used to calculate pre-CRT LCR and post-CRT LCR. The median LCR was used to stratify patients into low and high LCR groups for analysis. The correlation between pre- and post-CRT LCR and clinical outcomes was retrospectively investigated.

RESULTS

The pre-CRT LCR was significantly higher than the post-CRT LCR (11,765 and 6780, respectively, P < 0.05). The 5-year overall survival rate was significantly higher for patients with high post-CRT LCR compared with low post-CRT LCR (90.6% and 65.5%, respectively, P < 0.05). In univariate analysis, post-CRT LCR, post-CRT neutrophil to lymphocyte ratio, and fStage were significant prognostic factors for overall survival. In multivariate analysis, post-CRT LCR, but not other clinicopathological factors or prognostic indexes, was a significant prognostic factor for overall survival (P < 0.05).

CONCLUSIONS

Post-CRT LCR could be a prognostic biomarker for patients with lower rectal cancer.

Effect of Cumulative Dexamethasone Dose during Concomitant Chemoradiation on Lymphopenia in Patients with Newly Diagnosed Glioblastoma

Background

Lymphopenia frequently occurs after concomitant chemoradiation (CCRT) in patients with glioblastoma (GBM) and is associated with worse overall survival (OS). A few studies have tried to identify risk factors for lymphopenia; however, the results were not clear. We aimed to identify potential risk factors for lymphopenia, focusing on the use of dexamethasone to control cerebral edema in patients with GBM.

Methods

The electronic medical records of 186 patients with newly diagnosed GBM treated at our institution between 2009 and 2017 were retrospectively examined. Acute lymphopenia was defined as total lymphocyte count less than 1,000 cells/µL at 4 weeks after completion of CCRT. Multivariate logistic regression analysis was used to identify independent risk factors for lymphopenia, and Cox regression analysis was used to identify independent risk factors for OS.

Results

Of the 125 eligible patients, 40 patients (32.0%) developed acute lymphopenia. Female sex and median daily dexamethasone dose ≥2 mg after initiation of CCRT were independent risk factors for acute lymphopenia on multivariate analysis. Acute lymphopenia, extent of surgical resection, and performance status were associated with OS; however, dexamethasone use itself was not an independent risk factor for poor OS.

Conclusion

Female sex, median daily dexamethasone dose ≥2 mg after initiation of CCRT until 4 weeks after completion of CCRT may be associated with acute lymphopenia. However, dexamethasone use itself did not affect OS in patients newly diagnosed with GBM. These results should be validated by further prospective studies controlling for other confounding factors.