[Mechanisms of radiation-induced lymphopenia and therapeutic impact]

Interpretable deep learning insights: Unveiling the role of 1 Gy volume on lymphopenia after radiotherapy in breast cancer

BACKGROUND

Lymphopenia is known for its significance on poor survivals in breast cancer patients. Considering full dosimetric data, this study aimed to develop and validate predictive models for lymphopenia after radiotherapy (RT) in breast cancer.

MATERIAL AND METHODS

Patients with breast cancer treated with adjuvant RT were eligible in this multicenter study. The study endpoint was lympopenia, defined as the reduction in absolute lymphocytes and graded lymphopenia after RT. The dose-volume histogram (DVH) data of related critical structures and clinical factors were taken into account for the development of dense neural network (DNN) predictive models. The developed DNN models were validated using external patient cohorts.

RESULTS

A total of 918 consecutive patients with invasive breast cancer enrolled. The training, testing, and external validating datasets consisted of 589, 203, and 126 patients, respectively. Treatment volumes at nearly all dose levels of the DVH were significant predictors for lymphopenia following RT, including volumes at very low-dose 1 Gy (V1) of organs at risk (OARs) including lung, heart and body, especially ipsilateral-lung V1. A final DNN model, combining full DVH dosimetric parameters of OARs and three key clinical factors, achieved a predictive accuracy of 75 % or higher.

CONCLUSION

This study demonstrated and externally validated the significance of full dosimetric data, particularly the volume of low dose at as low as 1 Gy of critical structures on lymphopenia after radiation in patients with breast cancer. The significance of V1 deserves special attention, as modern VMAT RT technology often has a relatively high value of this parameter. Further study is warranted for RT plan optimization.

Radiation-induced lymphopenia and the survival of women with cervical cancer: a meta-analysis

The current systematic analysis and meta-analysis was aimed to evaluate the association between radiation-induced lymphopenia (RIL) and survival of women with cervical cancer (CC). PubMed, Embase, Web of Science, and Cochrane Library were searched for relevant cohort studies comparing survival between women with CC who developed versus not developed RIL after radiotherapy. We pooled the results using a random-effects model that incorporates heterogeneity. In the meta-analysis, 952 women with CC were included from eight cohort studies. Overall, 378 (39.7%) of them had RIL after radiotherapy. During a median follow-up duration of 41.8 months, pooled results showed that RIL was independently associated with poor overall survival (hazard ratio [HR]: 2.67, 95% confidence interval [CI]: 1.81 to 3.94, p < 0.001; I² = 20%) and progression-free survival (HR: 2.17, 95% CI: 1.58 to 2.98, p < 0.001; I² = 0%). Predefined subgroup analyses showed similar results in patients with grade 3-4 and grade 4 RIL, in patients with RIL diagnosed during or after the radiotherapy, and in studies with quality score of seven or eight points (p values for subgroup effect all < 0.05). In conclusion, women with RIL were associated with poor survival after radiotherapy for CC.

Pretreatment neutrophil to lymphocyte ratio as prognostic factor in metastatic breast cancer treated with cyclin dependent kinase 4/6 inhibitors

Background

Cyclin dependent kinase inhibitors (CdK4/6i) changed the course of hormone receptor positive (HR+) HER2 negative (HER2-) metastatic breast cancer (mBC). To date, no factors have been shown to predict response to CdK4/6i. Neutrophil-to-lymphocyte ratio (NLR), an indicator of the host systemic inflammatory response, is an independent prognostic factor for survival in cancers. We conducted this study to evaluate the impact of NLR on survival in mBC patients treated with first line CdK4/6i.

Methods

All mBC patients treated with first line CdK4/6i between November 2015 and December 2019 were retrospectively included. The biomarker threshold was defined using ROC curves. We analyzed progression free survival (PFS), overall survival (OS), 12-month PFS and response rate according to NLR in univariable and multivariable analysis.

Results

A total of 126 patients treated with palbociclib (n=101), ribociclib (n=18) or abemaciclib (n=7) were included, with a median follow-up of 33 months [range: 2.9-57]. Median age was 65 years [29-86], 40% patients had good performance status (ECOG-PS 0). Most patients (71%) were included at the metastatic relapse stage and 29% had only bone metastases. Median PFS and median OS were 27 and 51 months, respectively. High NLR (≥ 2.53) was significantly associated with worse PFS (Hazard Ratio (HR)=0.50, CI_95% = [0.32-0.79]) and worse OS (HR=0.45, [CI_95%: 0.23-0.87]). In multivariable analysis, NLR and ECOG PS were independently factors associated with PFS (p=0.016 and p=0.001, respectively).

Conclusion

High NLR was associated with worse PFS and OS in HR+ HER2- mBC patients treated with first line CdK4/6i. NLR is a reliable and inexpensive prognostic marker, easily accessible in routine clinical practice, which could help optimize the therapeutic strategy. These results need to be confirmed in larger prospective studies.

Lymphopenic condition enhanced the antitumor immunity of PD-1-knockout T cells mediated by CRISPR/Cas9 system in malignant melanoma

BACKGROUND

Adoptive transfer of PD-1 knockout T cells mediated by CRISPR/Cas9 technology has been used in various cancers and got satisfactory treatment effectiveness. However, the effectiveness was limited due to the low proliferation ability, antigen recognition ability and short lifetime of T cells in vivo.

METHOD

In this study, PD-1 knockout T cells mediated by CRISPR/Cas9 system were transferred into lymphopenic mice after sub-lethal dose of total body irradiation. The antitumor effects of PD-1 knockout T cells were comprehensively analyzed by flow cytometry. Moreover, PD-L1 knockout B16 cells were inoculated subcutaneously in lymphopenic mice receiving infusion of naïve T cells to value the role of PD-1/PD-L1 axis on lymphopenia-induced antitumor immunity RESULT: In this study, we found that the PD-1-knockout T cells underwent several rounds of homeostatic proliferation in vivo when they were transferred into lymphopenic mice. The number of IFN-γ-releasing CTL was significantly increased and the tumor growth was remarkably inhibited in lymphopenic mice receiving infusion of PD-1 knockout T cells. The expression of PD-L1 on tumor cells rose smartly in lymphopenic mice undergoing homeostatic proliferation. PD-L1 gene knockout on B16 melanoma cells could effectively enhance the antitumor immunity mediated by the homeostatic proliferation of T cells and significantly inhibited the growth of tumor CONCLUSION: These findings suggested that lymphopenic condition after total body irradiation might be able to create an environment to promote the PD-1 knockout T cells to recognize tumor antigen and undergo homeostatic proliferation, thus induced a more powerful antitumor immunity than adoptively transferring into immunocompetent hosts.

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.

Prognostic Significance of Circulating Lymphocyte Subsets Before Treatment in Patients with Nasopharyngeal Carcinoma

Purpose

We set out to explore the prognostic value of circulating lymphocyte subsets in patients with nasopharyngeal carcinoma (NPC) before treatment and to investigate changes in lymphocyte subsets resulting from chemoradiotherapy.

Patients and Methods

This retrospective study included 677 patients with non-metastatic NPC. The cutoff value of lymphocyte subsets was determined by the receiver operating characteristic curve (ROC), and the prognostic significance of lymphocyte subsets was evaluated by the Log rank test and Cox proportional hazards model. The endpoints were overall survival (OS), progression-free survival (PFS), locoregional relapse-free survival (LRFS) and distant metastasis-free survival (DMFS). Differences in lymphocyte subsets before and after chemoradiotherapy were analyzed by Wilcoxon signed rank test.

Results

NPC patients with high levels of CD19⁺ B cells (>9.55%) had better 5-year OS (90.4% VS 76.8%, P < 0.001), 5-year PFS (85.3% VS 71.6%, P < 0.001) and 5-year DMFS (94% VS 86.8%, P = 0.002) than patients with low levels of CD19⁺ B cells. Patients with high levels of CD4⁺ T cells (> 37.05%) had better 5-year PFS (83% VS 74.2%, P = 0.015) and better 5-year DMFS (95.8% VS 86.7%, P < 0.001) than those with low levels of CD4⁺ T cells. Multivariate analyses indicated that CD19⁺ B cell was an independent prognostic factor for OS, PFS and DMFS in NPC. And CD4⁺ T cell was an independent prognostic factor for PFS and DMFS. Within 1 month after chemoradiotherapy, the percentages of CD4⁺ T cells, CD19⁺ B cells, and the CD4/CD8 ratio decreased significantly, while the percentages of CD8⁺ T cells increased significantly.

Conclusion

NPC patients with low levels of CD19⁺ B cells or CD4⁺ T cells before treatment have a poor prognosis. In addition, chemoradiotherapy may reduce the body’s immune function in NPC patients.

Anti-PD-1/Anti-PD-L1 Drugs and Radiation Therapy: Combinations and Optimization Strategies

Simple Summary

Although immune checkpoint blockade has yielded unprecedented and durable responses in cancer patients, the efficacy of this treatment remains limited. Radiation therapy can induce immunogenic cell death that contributes to the local efficacy of irradiation. However, radiation-induced systemic responses are scarce. Studies combining radiation with checkpoint inhibitors suggest a synergistic potential of this strategy. In this review, we focused on parameters that can be optimized to enhance the anti-tumor immune response that results from this association, in order to achieve data on dose, fractionation, target volume, lymph nodes sparing, radiation particles, and other immunomodulatory agents. These factors should be considered in future trials for better clinical outcomes. To this end, we discussed the main preclinical and clinical data available to optimize the efficacy of the treatment combination.

Abstract

Immune checkpoint inhibitors have been associated with long-term complete responses leading to improved overall survival in several cancer types. However, these novel immunotherapies are only effective in a small proportion of patients, and therapeutic resistance represents a major limitation in clinical practice. As with chemotherapy, there is substantial evidence that radiation therapy promotes anti-tumor immune responses that can enhance systemic responses to immune checkpoint inhibitors. In this review, we discuss the main preclinical and clinical evidence on strategies that can lead to an enhanced response to PD-1/PD-L1 blockade in combination with radiation therapy. We focused on central issues in optimizing radiation therapy, such as the optimal dose and fractionation for improving the therapeutic ratio, as well as the impact on immune and clinical responses of dose rate, target volume, lymph nodes irradiation, and type of radiation particle. We explored the addition of a third immunomodulatory agent to the combination such as other checkpoint inhibitors, chemotherapy, and treatment targeting the tumor microenvironment components. The strategies described in this review provide a lead for future clinical trials.

Radiotherapy in the Era of Immunotherapy With a Focus on Non-Small-Cell Lung Cancer: Time to Revisit Ancient Dogmas?

Radiation-induced immune effects have been extensively deciphered over the last few years, leading to the concept of the dual immune effect of radiotherapy with both immunostimulatory and immunosuppressive effects. This explains why radiotherapy alone is not able to drive a strong anti-tumor immune response in most cases, hence underlining the rationale for combining both radiotherapy and immunotherapy. This association has generated considerable interest and hundreds of trials are currently ongoing to assess such an association in oncology. However, while some trials have provided unprecedented results or shown much promise, many hopes have been dashed. Questions remain, therefore, as to how to optimize the combination of these treatment modalities. This narrative review aims at revisiting the old, well-established concepts of radiotherapy relating to dose, fractionation, target volumes and organs at risk in the era of immunotherapy. We then propose potential innovative approaches to be further assessed when considering a radio-immunotherapy association, especially in the field of non-small-cell lung cancer (NSCLC). We finally propose a framework to optimize the association, with pragmatic approaches depending on the stage of the disease.

Radiotherapy-Immunotherapy Combination: How Will We Bridge the Gap Between Pre-Clinical Promise and Effective Clinical Delivery?

Radiotherapy (RT) is highly effective at directly killing tumor cells and plays an important part in cancer treatments being delivered to around 50% of all cancer patients. The additional immunomodulatory properties of RT have been investigated, and if exploited effectively, have the potential to further improve the efficacy of RT and cancer outcomes. The initial results of combining RT with immunomodulatory agents have generated promising data in pre-clinical studies, which has in turn led to a large number of RT and immunotherapy clinical trials. The overarching aim of these combinations is to enhance anti-tumor immune responses and improve responses rates and patient outcomes. In order to maximize this undoubted opportunity, there remain a number of important questions that need to be addressed, including: (i) the optimal RT dose and fractionation schedule; (ii) the optimal RT target volume; (iii) the optimal immuno-oncology (IO) agent(s) to partner with RT; (iv) the optimal site(s)/route(s) of administration of IO agents; and finally, the optimal RT schedule. In this review, we will summarize progress to date and identify current gaps in knowledge that need to be addressed in order to facilitate effective clinical translation of RT and IO agent combinations.