Peripheral Blood Lymphocyte Depletion After Hepatic Arterial 90Yttrium Microsphere Therapy for Hepatocellular Carcinoma

Progressive Multifocal Leukoencephalopathy in a Patient With Cirrhosis and Hepatocellular Carcinoma

The following case describes a constellation of progressive cognitive and motor deficits in a 73-year-old man with cirrhosis and history of early-stage hepatocellular carcinoma confined to his liver. He had deficits in calculation, language, and writing, as well as subtle right-sided weakness. Magnetic resonance imaging (MRI) of the brain demonstrated non-enhancing white matter lesions without mass effect in the bilateral parietal and left occipitotemporal regions, correlating with neurologic exam findings. The patient's basic blood and cerebrospinal fluid (CSF) studies were within normal limits. Our differential included inflammatory and demyelinating conditions, hepatic encephalopathy, posterior reversible encephalopathy syndrome, progressive multifocal leukoencephalopathy (PML), and central nervous system (CNS) tumors. He did not improve with an empiric course of high-dose steroids or adequate hepatic encephalopathy treatment. A repeat lumbar puncture sent for additional CSF studies revealed a positive John Cunningham (JC) virus PCR test, confirming diagnosis of PML. Although the patient did not have any known overt immunosuppressive condition or treatment, the patient's cirrhosis and age placed him at higher risk for developing JC virus CNS reactivation. In a published case series of patients with PML and no classic immunosuppressive condition that includes several patients with concomitant cirrhosis, prognosis is much worse compared to those with known, reversible causes of immunosuppression.

New frontiers in radioembolization

Radioembolization is a locoregional transarterial therapy that combines radionuclide and micron-sized beads to deliver radiation internally to the target tumors based on the arterial blood flow. While initially developed as a palliative treatment option, radioembolization is now used for curative intent treatment, neoadjuvant therapy, and method to downstage or bridge for liver transplant. Radioembolization has become increasingly utilized and is an important therapeutic option for the management of hepatocellular carcinoma and liver metastasis. This article provides an overview of the techniques, challenges, and novel developments in radioembolization, including new dosimetry techniques, radionuclides, and new target tumors.

Clinical Translation of a Deep Learning Model of Radiation-Induced Lymphopenia for Esophageal Cancer

Purpose

Radiation-induced lymphopenia is a common immune toxicity that adversely impacts treatment outcomes. We report here our approach to translate a deep-learning (DL) model developed to predict severe lymphopenia risk among esophageal cancer into a strategy for incorporating the immune system as an organ-at-risk (iOAR) to mitigate the risk.

Materials and Methods

We conducted "virtual clinical trials" utilizing retrospective data for 10 intensity-modulated radiation therapy (IMRT) and 10 passively-scattered proton therapy (PSPT) esophageal cancer patients. For each patient, additional treatment plans of the modality other than the original were created employing standard-of-care (SOC) dose constraints. Predicted values of absolute lymphocyte count (ALC) nadir for all plans were estimated using a previously-developed DL model. The model also yielded the relative magnitudes of contributions of iOARs dosimetric factors to ALC nadir, which were used to compute iOARs dose-volume constraints, which were incorporated into optimization criteria to produce "IMRT-enhanced" and "intensity-modulated proton therapy (IMPT)-enhanced" plans.

Results

Model-predicted ALC nadir for the original IMRT (IMRT-SOC) and PSPT plans agreed well with actual values. IMPT-SOC showed greater immune sparing vs IMRT and PSPT. The average mean body doses were 13.10 Gy vs 7.62 Gy for IMRT-SOC vs IMPT-SOC for patients treated with IMRT-SOC; and 8.08 Gy vs 6.68 Gy for PSPT vs IMPT-SOC for patients treated with PSPT. For IMRT patients, the average predicted ALC nadir of IMRT-SOC, IMRT-enhanced, IMPT-SOC, and IMPT-enhanced was 281, 327, 351, and 392 cells/µL, respectively. For PSPT patients, the average predicted ALC nadir of PSPT, IMPT-SOC, and IMPT-enhanced was 258, 316, and 350 cells/µL, respectively. Enhanced plans achieved higher predicted ALC nadir, with an average improvement of 40.8 cells/µL (20.6%).

Conclusion

The proposed DL model-guided strategy to incorporate the immune system as iOAR in IMRT and IMPT optimization has the potential for radiation-induced lymphopenia mitigation. A prospective clinical trial is planned.

Paraneoplastic Diarrhea From Medullary Thyroid Carcinoma Resolved With Yttrium-90 Radioembolization of Liver Metastases

Medullary thyroid carcinoma (MTC) can often have an indolent course despite distant metastatic disease. Additionally, given that metastatic MTC is incurable and systemic therapies have non-negligeable toxicities, localized treatments are often favored in presence of oligo-progressive disease. Transarterial radioembolization (TARE) with yttrium-90 (Y90) has emerged as a safe and efficacious treatment for nonresectable primary and metastatic liver tumors, yet data supporting its use in metastatic MTC are limited. We present the case of a patient with hereditary MTC and large bilobar liver metastases who demonstrated tumor response and resolution of their paraneoplastic diarrhea following TARE with Y90 microspheres.

A Partial Tumor Irradiation Approach for Complex Bulky Disease

A large proportion of cancer patients present with unresectable bulky disease at baseline or following treatment failure. The data available in the literature suggest that the vast majority of these patients do not benefit from available standard therapies. Therefore the clinical outcomes are poor; patients are desperate and usually relegated to palliative or best supportive care as the only options. Large tumor masses are usually hypoxic, resistant to radiation and systemic therapy, with extensive regional infiltration of the surrounding critical organs, the presence of which makes it impossible to deliver a radical dose of radiation. Promising data in terms of improved therapeutic ratio where such complex tumors are concerned can be seen with the use of new emerging unconventional radiotherapy techniques known as spatially fractionated radiotherapies (SFRT). One of them is PATHY, or PArtial Tumor irradiation targeting HYpoxic segment, which is characterized by a very short treatment course offering a large spectrum of therapeutic benefits in terms of the symptom relief, quality of life, local tumor control, neoadjuvant and immunomodulatory effects.

The immune response of hepatocellular carcinoma after locoregional and systemic therapies: The available combination option for immunotherapy

Hepatocellular carcinoma (HCC) is associated with a highly heterogeneous immune environment that produces an immune response to various locoregional treatments (LRTs), which in turn affects the effectiveness of immunotherapy. Although LRTs still dominate HCC therapies, 50-60% of patients will ultimately be treated with systemic therapies and might receive those treatments for the rest of their life. TACE, SIRT, and thermal ablation can dramatically increase the immunosuppressive state of HCC, a condition that can be addressed by combination with immunotherapy to restore the activity of lymphocytes and the secretion of cellular immune factors. Immune treatment with locoregional and systemic treatments has dramatically changed the management of HCC. In this review, we examine the research on the changes in the immune microenvironment after locoregional or systemic treatment. We also summarize the regulation of various immune cells and immune factors in the tumor microenvironment and discuss the different infiltration degrees of immune cells and factors on the prognosis of HCC to better compare the efficacy between different treatment methods from the perspective of the tumor microenvironment. This information can be used to help develop treatment options for the upcoming new era of HCC treatment in the future.

Predicting Severity of Radiation Induced Lymphopenia in Individual Proton Therapy Patients for Varying Dose Rate and Fractionation Using Dynamic 4-Dimensional Blood Flow Simulations

PURPOSE

Radiation-induced lymphopenia has gained attention recently as the result of its correlation with survival in a range of indications, particularly when combining radiation therapy (RT) with immunotherapy. The purpose of this study is to use a dynamic blood circulation model combined with observed lymphocyte depletion in patients to derive the in vivo radiosensitivity of circulating lymphocytes and study the effect of RT delivery parameters.

METHODS AND MATERIALS

We assembled a cohort of 17 patients with hepatocellular carcinoma treated with proton RT alone in 15 fractions (fx) using conventional dose rates (beam-on time [BOT], 120 seconds) for whom weekly absolute lymphocyte counts (ALCs) during RT and follow-up were available. We used HEDOS, a time-dependent, whole-body, blood flow computational framework, in combination with explicit liver blood flow modeling, to calculate the dose volume histograms for circulating lymphocytes for changing BOTs (1 second-300 seconds) and fractionations (5 fx, 15 fx). From this, we used the linear cell survival model and an exponential model to determine patient-specific lymphocyte radiation sensitivity, α, and recovery, σ, respectively.

RESULTS

The in vivo-derived patient-specific α had a median of 0.65 Gy-1 (range, 0.30-1.38). Decreasing BOT to 1 second led to an increased average end-of-treatment ALC of 27.5%, increasing to 60.3% when combined with the 5-fx regimen. Decreasing to 5 fx at the conventional dose rate led to an increase of 17.0% on average. The benefit of both increasing dose rate and reducing the number of fractions was patient specificࣧpatients with highly sensitive lymphocytes benefited most from decreasing BOT, whereas patients with slow lymphocyte recovery benefited most from the shorter fractionation regimen.

CONCLUSIONS

We observed that increasing dose rate at the same fractionation reduced ALC depletion more significantly than reducing the number of fractions. High-dose-rates led to an increased sparing of lymphocytes when shortening the fractionation regimen, particularly for patients with radiosensitive lymphocytes at elevated risk.

Establishment and validation of a cholesterol metabolism-related prognostic signature for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents the most important type of liver cancer, the 5-year survival rate for advanced HCC is 2%. The heterogeneity of HCC makes previous models fail to achieve satisfactory results. The role of Cholesterol-based metabolic reprogramming in cancer has attracted more and more attention. In this study, we screened cholesterol metabolism-related genes (CMRGs) based on a systematical analysis from TCGA and GEO database. Then, we constructed a prognostic signature based on the screened 5 CMRGs: FDPS, FABP5, ANXA2, ACADL and HMGCS2. The clinical value of the five CMRGs was validated by TCGA database and HPA database. HCC patients were assigned to the high-risk and low-risk groups on the basis of median risk score calculated by the five CMRGs. We evaluated the signature in TCGA database and validated in ICGC database. The results revealed that the prognostic signature had good prognostic performance, even among different clinicopathological subgroups. The function analysis linked CMRGs with KEGG pathway, such as cell adhesion molecules, drug metabolism-cytochrome P450 and other related pathways. In addition, patients in the high-risk group exhibited characteristics of high TP53 mutation, high immune checkpoints expression and high immune cell infiltration. Furthermore, based on the prognostic signature, we identified 25 most significant small molecule drugs as potential drugs for HCC patients. Finally, a nomogram combined risk score and TNM stage was constructed. These results indicated our prognostic signature has an excellent prediction performance. This study is expected to provide a potential diagnostic and therapeutic strategies for HCC.

Intraarterial Therapies for the Management of Hepatocellular Carcinoma

Image-guided locoregional therapies play a crucial role in the management of patients with hepatocellular carcinoma (HCC). Transarterial therapies consist of a group of catheter-based treatments where embolic agents are delivered directly into the tumor via their supplying arteries. Some of the transarterial therapies available include bland embolization (TAE), transarterial chemoembolization (TACE), drug-eluting beads-transarterial chemoembolization (DEB-TACE), selective internal radioembolization therapy (SIRT), and hepatic artery infusion (HAI). This article provides a review of pre-procedural, intra-procedural, and post-procedural aspects of each therapy, along with a review of the literature. Newer embolotherapy options and future directions are also briefly discussed.

Prognosis of hepatocellular carcinoma and its association with immune cells using systemic inflammatory response index

Aim: To explore the prognostic value of the systemic inflammatory response index (SIRI) and peripheral blood T-cell subsets in patients with hepatocellular carcinoma (HCC) and the relationship between them. Materials & methods: We treated 352 patients with HCC with sorafenib and/or immune checkpoint inhibitors (ICIs) and analyzed SIRI and peripheral blood T cells. Results: SIRI was an independent prognostic factor for patients with HCC receiving systemic therapy. Patients with high SIRI and low baseline peripheral blood T-cell counts showed a poor response to ICIs. SIRI was significantly and negatively correlated with CD3⁺, CD4⁺ and CD8⁺ T-cell counts. Conclusion: SIRI markers can be employed to noninvasively assess the presence of cancer-promoting inflammation in the tumor microenvironment and predict the efficacy of targeted therapy and immunotherapy.

Targeting Immune Cells in the Tumor Microenvironment of HCC: New Opportunities and Challenges

Immune associated cells in the microenvironment have a significant impact on the development and progression of hepatocellular carcinoma (HCC) and have received more and more attention. Different types of immune-associated cells play different roles, including promoting/inhibiting HCC and several different types that are controversial. It is well known that immune escape of HCC has become a difficult problem in tumor therapy. Therefore, in recent years, a large number of studies have focused on the immune microenvironment of HCC, explored many mechanisms worth identifying tumor immunosuppression, and developed a variety of immunotherapy methods as targets, laying the foundation for the final victory in the fight against HCC. This paper reviews recent studies on the immune microenvironment of HCC that are more reliable and important, and provides a more comprehensive view of the investigation of the immune microenvironment of HCC and the development of more immunotherapeutic approaches based on the relevant summaries of different immune cells.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Shifting the Immune-Suppressive to Predominant Immune-Stimulatory Radiation Effects by SBRT-PArtial Tumor Irradiation Targeting HYpoxic Segment (SBRT-PATHY)

Simple Summary

This review presents and summarizes the key components and outcomes of a novel, unconventional radiation approach aimed to exploit immune-stimulatory radiation effects which, being added to direct radiation tumor cell killing, may improve the therapeutic ratio of radiotherapy. This technique, as a product of translational oncology research, was intentionally developed for the induction of immune-mediated bystander and abscopal effects in the treatment of unresectable bulky tumors which have much fewer therapeutic options and show poor prognoses after conventional treatments. This review offers insights into a unique unconventional radiotherapy technique which, due to its higher immunogenic potential, may improve the prognosis of patients affected by highly complex malignancies, providing additional opportunities for future research in terms of combining novel immuno-modulating agents with more modern radiotherapy approaches.

Abstract

Radiation-induced immune-mediated abscopal effects (AE) of conventional radiotherapy are very rare. Whole-tumor irradiation leads to lymphopenia due to killing of immune cells in the tumor microenvironment, resulting in immunosuppression and weak abscopal potential. This limitation may be overcome by partial tumor irradiation sparing the peritumoral immune-environment, and consequent shifting of immune-suppressive to immune-stimulatory effect. This would improve the radiation-directed tumor cell killing, adding to it a component of immune-mediated killing. Our preclinical findings showed that the high-single-dose irradiation of hypoxic tumor cells generates a stronger bystander effect (BE) and AE than the normoxic cells, suggesting their higher “immunogenic potential”. This led to the development of a novel Stereotactic Body RadioTherapy (SBRT)-based PArtial Tumor irradiation targeting HYpoxic segment (SBRT-PATHY) for induction of the immune-mediated BE and AE. Encouraging SBRT-PATHY-clinical outcomes, together with immunohistochemical and gene-expression analyses of surgically removed abscopal-tumor sites, suggested that delivery of the high-dose radiation to the partial (hypoxic) tumor volume, with optimal timing based on the homeostatic fluctuation of the immune response and sparing the peritumoral immune-environment, would significantly enhance the immune-mediated anti-tumor effects. This review discusses the current evidence on the safety and efficacy of SBRT-PATHY in the treatment of unresectable hypoxic bulky tumors and its bystander and abscopal immunomodulatory potential.

Prediction of survival according to kinetic changes of cytokines and hepatitis status following radioembolization with yttrium-90 microspheres

BACKGROUND/PURPOSE

Yttrium-90 radioembolization (Y90-RE) may exert an immunomodulatory effect on the tumor microenvironment of hepatocellular carcinoma (HCC). Whether the host immune alterations after Y90-RE correlated with outcomes and whether Y90-RE affects viral hepatitis reactivation remains unclear.

METHODS

Between July 2014 and July 2015, 18 patients undergoing Y90-RE for HCC were prospectively enrolled. Serum levels of virological markers, cytokines and chemokines were measured at baseline, 2, 4, and 12 weeks after Y90-RE. Factors associated with the clinical outcomes were evaluated.

RESULTS

The disease control rate of Y90-RE was 44.4% (8 of 18) at 12 weeks, including 1 case with complete response, 4 cases with partial response, and 3 cases with stable disease. Significant elevation from baseline to week 2 and week 4 were noted in IL-10 level (8.4 ± 33.8, 15.7 ± 31.6, and 16.0 ± 41.7 pg/mL, P = 0.041 and 0.013, respectively) and IP-10 level (113.5 ± 97.8, 189.1 ± 164.4, and 168.6 ± 150.5 pg/mL, P = 0.027 and 0.026, respectively). After Y90-RE, transient HBV reactivation occurred in 2 patients, and 1 out of 3 HCV-infected patients exhibited HCV reactivation. Univariate analysis revealed that lower baseline IP-10 (≤200 pg/mL) and alanine aminotransferase (ALT) (≤50 U/L) levels were associated with better overall survival. Multivariate analysis identified an IP-10 level of 200 pg/mL (HR = 4.374, P = 0.045) as a predictor of overall survival.

CONCLUSION

Baseline serum IP-10 level is a predictor of survival for HCC patients undergoing Y90-RE. HBV and HCV reactivation may develop after Y90-RE treatment.

The future of radiation-induced abscopal response: beyond conventional radiotherapy approaches

Advances in the immunological pharmaceuticals, such as checkpoint inhibitors and agonists, have positive implications for the future of the radiotherapy abscopal response. A once rare phenomenon, whereby distant nonirradiated tumor sites regressed after radiotherapy alone, may become more common when combined with the immune modulating agents. Radiotherapy can increase neoantigen expression, increased tumor PD-L1 expression, increase MHC class I expression, reverse exhausted CD8 T cells and increase tumor-infiltrating tumors within the tumor microenvironment. These changes in the tumor and the tumor microenvironment after radiotherapy could potentiate responses to anti-CTL-4, anti-PD-L1/PD-1 and other immunotherapy agents. Thus, advances in checkpoint inhibitors have increased interest in re-evaluation of the role of conventional radiotherapy approaches on the immune system. We reviewed newer nonconventional approaches such as SBRT-PATHY, GRID, FLASH, carbon ion and proton therapy and their role in eliciting immune responses. We believe that combining these novel radiation methods may enhance the outcome with the newly US FDA approved immune modulating agents.

Mono-institutional phase 2 study of innovative Stereotactic Body RadioTherapy targeting PArtial Tumor HYpoxic (SBRT-PATHY) clonogenic cells in unresectable bulky non-small cell lung cancer: profound non-targeted effects by sparing peri-tumoral immune microenvironment

BACKGROUND

Radiotherapy-induced lymphopenia may be limiting the success of therapy and could also negatively affect the ability of immune system in mediating the bystander (BE) and abscopal effects (AE). A novel SBRT-based PArtial Tumor irradiation of HYpoxic clonogenic cells (SBRT-PATHY) for induction of the tumoricidal BE and AE by sparing the peritumoral immune microenvironment and regional circulating lymphocytes has been developed to enhance the radiotherapy therapeutic ratio of advanced lung cancer. The aim of this retrospective review of prospectively collected mono-institutional phase 2 study was to compare the outcomes between unconventional SBRT-PATHY and standard of care in unresectable stage IIIB/IV bulky NSCLC.

MATERIALS AND METHODS

Sixty patients considered inoperable or unsuitable for radical radio-chemotherapy were enrolled and treated using the following 3 regimens: SBRT-PATHY (group I, n = 20 patients), recommended standard of care chemotherapy (group II, n = 20 patients), and institutional conventional palliative radiotherapy (group III, n = 20 patients).

RESULTS

Median follow-up was 13 months. The 1-year overall survival was 75, 60, and 20% in groups 1, 2 and 3, respectively (p = 0.099). The 1-year cancer specific survival was 90, 60, and 20% in groups 1, 2, and 3, respectively (p = 0.049). Bulky tumor control rate was 95% for SBRT-PATHY compared with 20% in the other two groups. BE and AE were seen by SBRT-PATHY in 95 and 45% of patients, respectively. Multi-variate analysis for cancer specific survival was significant for treatment effect with SBRT-PATHY (p < 0.001) independent of age, sex, performance status, histology, stage, treated bulky site and tumor diameter. SBRT-PATHY resulted in lower toxicity (p = 0.026), and improved symptom control (p = 0.018) when compared to other two treatment options.

CONCLUSION

SBRT-PATHY improved treatment outcomes in unresectable NSCLC and should be investigated in larger trials. Present study has been retrospectively registered on 8th of August 2019 by the ethic committee for Austrian region "Kärnten "in Klagenfurt (AUT), under study number A 31/19.

Ultra high dose rate (35 Gy/sec) radiation does not spare the normal tissue in cardiac and splenic models of lymphopenia and gastrointestinal syndrome

Recent reports have shown that very high dose rate radiation (35–100 Gy/second) referred to as FLASH tends to spare the normal tissues while retaining the therapeutic effect on tumor. We undertook a series of experiments to assess if ultra-high dose rate of 35 Gy/second can spare the immune system in models of radiation induced lymphopenia. We compared the tumoricidal potency of ultra-high dose rate and conventional dose rate radiation using a classical clonogenic assay in murine pancreatic cancer cell lines. We also assessed the lymphocyte sparing potential in cardiac and splenic irradiation models of lymphopenia and assessed the severity of radiation-induced gastrointestinal toxicity triggered by the two dose rate regimes in vivo. Ultra-high dose rate irradiation more potently induces clonogenic cell death than conventional dose rate irradiation with a dose enhancement factor at 10% survival (DEF₁₀) of 1.310 and 1.365 for KPC and Panc02 cell lines, respectively. Ultra-high dose rate was equally potent in depleting CD3, CD4, CD8, and CD19 lymphocyte populations in both cardiac and splenic irradiation models of lymphopenia. Radiation-induced gastrointestinal toxicity was more pronounced and mouse survival (7 days vs. 15 days, p = 0.0001) was inferior in the ultra-high dose rate arm compared to conventional dose rate arm. These results suggest that, contrary to published data in other models of radiation-induced acute and chronic toxicity, dose rates of 35 Gy/s do not protect mice from the detrimental side effects of irradiation in our models of cardiac and splenic radiation-induced lymphopenia or gastrointestinal mucosal injury.

Impaired lymphocyte function in patients with hepatic malignancies after selective internal radiotherapy

The purpose of our study was to assess the immune function of patients with inoperable hepatic malignancies after treatment with selective internal radiotherapy (SIRT) and to identify possible correlations with clinical parameters. In 25 patients receiving SIRT lymphocyte proliferation and the production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin-10) after stimulation with mitogens and microbial antigens were tested prior to therapy, directly after therapy (day 1) and at day 2, 7 and 28 post therapy using the lymphocyte transformation test and enzyme-linked immunospot assays. Absolute counts and percentages of leukocyte and lymphocyte subsets were determined by flow cytometry. The most prominent finding was an immediate and significant (p < 0.05) decrease of lymphocyte proliferation and interferon-γ production directly after therapy which lasted until day 28 and was stronger upon stimulation with microbial antigens than with mitogens. Moreover, lymphopenia was revealed, affecting all lymphocyte subsets (CD3+, CD4+, CD8+ T cells, CD4+ CD8+ T cells, B cells and NK cells). SIRT led to a reduction in the percentage of activated HLA-DR+ monocytes and of CD45R0+ memory T cells. Higher radiation activity, the presence of liver cirrhosis, chronic kidney disease, diabetes mellitus and metastases were unfavorable factors for immunocompetence, while a better Eastern Cooperative Oncology Group performance status was associated with stronger immunological reactions. In conclusion, SIRT leads to severe impairment of cellular in vitro immune responses. Further studies are needed to assess a potential clinical impact.

Safety of selective internal radiation therapy (SIRT) with yttrium-90 microspheres combined with systemic anticancer agents: expert consensus

Selective internal radiation therapy (SIRT) with microspheres labelled with the β-emitter yttrium-90 (Y-90) enables targeted delivery of radiation to hepatic tumors. SIRT is primarily used to treat inoperable primary or metastatic liver tumors. Eligible patients have usually been exposed to a variety of systemic anticancer therapies, including cytotoxic agents, targeted biologics, immunotherapy and peptide receptor radionuclide therapy (PRRT). All these treatments have potential interactions with SIRT; however, robust evidence on the safety of these potential combinations is lacking. This paper provides current clinical experiences and expert consensus guidelines for the use of SIRT in combination with the anticancer treatment agents likely to be encountered in clinical practice. It was agreed by the expert panel that precautions need to be taken with certain drugs, but that, in general, systemic therapies do not necessarily have to be stopped to perform SIRT. The authors recommend stopping vascular endothelial growth factor inhibitors 4-6 weeks before SIRT, and restart after the patient has recovered from the procedure. It may also be prudent to stop potent radiosensitizers such as gemcitabine therapy 4 weeks before SIRT, and restart treatment at least 2‒4 weeks later. Data from phase III studies combining SIRT with fluorouracil (5FU) or folinic acid/5FU/oxaliplatin (FOLFOX) suggest that hematological toxicity is more common from the combination than it is from chemotherapy without SIRT. There is no evidence to suggest that chemotherapy increases SIRT-specific gastro-intestinal or liver toxicities.

Impairment of lymphocyte function following yttrium-90 DOTATOC therapy

The radiolabeled somatostatin analogue, yttrium-90 DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC), is currently applied to treat advanced somatostatin receptor-positive tumors, e.g., neuroendocrine tumors of the pancreas, lung or gut. However, effects of this treatment on antimicrobial immune responses are not yet defined. In 20 patients treated with DOTATOC, cellular in vitro immune function was determined. Their antimicrobial lymphocyte responses were assessed by lymphocyte transformation test and enzyme-linked immunospot-measuring lymphocyte proliferation and on a single cell level production of pro- and anti-inflammatory cytokines (interferon-γ and interleukin-10)-prior to therapy, at day 1, day 7 and day 90 post-therapy. Proliferative lymphocyte responses and interferon-γ production after in vitro stimulation with microbial antigens were non-significantly suppressed at day 1 and significantly (p < 0.05) at day 7 versus pre-therapy. In vitro immune responses did not fully recover until day 90. In contrast, at day 1 interleukin-10 production was significantly (p < 0.05) increased. Taken together, we observed a decrease in pro-inflammatory immune responses after DOTATOC therapy. Patients with versus without bone metastases displayed significantly (p < 0.05) lower cellular immune responses toward several microbial antigens. Progressive disease and higher tumor burden could also be defined as factors associated with impaired immune function. Spearman correlation analysis indicated that cellular in vitro immunity was positively correlated with kidney function; better kidney function led to stronger immune responses. In conclusion, DOTATOC therapy caused a decrease in in vitro immune responses against microorganisms. The clinical impact needs to be evaluated in further studies.

Acute hematologic and mucosal toxicities in head and neck cancer patients undergoing chemoradiotherapy: a comparison of 3D-CRT, IMRT, and helical tomotherapy

IMRT and helical tomotherapy for head and neck cancer (HNC) treatment are associated with higher doses to certain non-target tissues than traditional static beam techniques. We hypothesized that this may lead to higher acute mucosal and hematologic toxicities. This analysis was limited to 178 patients receiving ≥60 Gy with concurrent weekly cisplatin. Radiation delivery used 3D-CRT in 41 patients (23%), conventional IMRT in 56 patients (31%), and helical tomotherapy in 81 patients (46%). Acute mucositis rates, weekly hematologic parameters, and ability to deliver planned chemotherapy cycles were examined for each patient during their course of chemoradiotherapy. Analysis showed patients were well balanced with regard to sex, age, and stage. Treatment time, as assessed by delivered monitor units, varied significantly between the 3D-CRT (median = 502), IMRT (median = 1087), and tomotherapy (median = 6757) cohorts. Acute mucositis grades did not significantly differ between the three subsets. Through six weeks of chemoradiotherapy, the median decline in hemoglobin was 15.6%, the median decline in platelets was 30.6%, and the median decline in leukocytes was 51.5%, but these drops were not significantly different between treatment cohorts. Chemotherapy was discontinued or held secondary to hematologic toxicity in 12% of 3D-CRT patients, 5% of IMRT patients and 15% of tomotherapy patients (p = 0.14). In conclusion, HNC patients undergoing high dose radiation with concurrent weekly cisplatin chemotherapy, the longer beam-on times and larger volumes of low-to-moderate radiation doses to non-target tissues associated with modern IMRT delivery techniques do not appear to result in increased acute hematologic or mucosal toxicities.

Clinical opportunities in combining immunotherapy with radiation therapy

Preclinical work in murine models suggests that local radiotherapy plus intratumoral syngeneic dendritic cells (DC) injection can mediate immunologic tumor eradication. Radiotherapy affects the immune response to cancer, besides the direct impact on the tumor cells, and other ways to coordinate immune modulation with radiotherapy have been explored. We review here the potential for immune-mediated anticancer activity of radiation on tumors. This can be mediated by differential antigen acquisition and presentation by DC, through changes of lymphocytes' activation, and changes of tumor susceptibility to immune clearance. Recent work has implemented the combination of external beam radiation therapy (EBRT) with intratumoral injection of DC. This included a pilot study of coordinated intraprostatic, autologous DC injection together with radiation therapy with five HLA-A2(+) subjects with high-risk, localized prostate cancer; the protocol used androgen suppression, EBRT (25 fractions, 45 Gy), DC injections after fractions 5, 15, and 25, and then interstitial radioactive implant. Another was a phase II trial using neo-adjuvant apoptosis-inducing EBRT plus intra-tumoral DC in soft tissue sarcoma, to test if this would increase immune activity toward soft tissue sarcoma associated antigens. In the future, radiation therapy approaches designed to optimize immune stimulation at the level of DC, lymphocytes, tumor and stroma effects could be evaluated specifically in clinical trials.