Stereotactic Body Radiotherapy Immunological Planning-A Review With a Proposed Theoretical Model

Radiotherapy-induced alterations in tumor microenvironment: metabolism and immunity

Tumor metabolism plays a pivotal role in shaping immune responses within the tumor microenvironment influencing tumor progression, immune evasion, and the efficacy of cancer therapies. Radiotherapy has been shown to impact both tumor metabolism and immune modulation, often inducing immune activation through damage-associated molecular patterns and the STING pathway. In this study, we analyse the particular characteristics of the tumour metabolic microenvironment and its effect on the immune microenvironment. We also review the changes in the metabolic and immune microenvironment that are induced by radiotherapy, with a focus on metabolic sensitisation to the effects of radiotherapy. Our aim is to contribute to the development of research ideas in the field of radiotherapy metabolic-immunological studies.

STRIvE-02: A First-in-Human Phase I Study of Systemically Administered B7-H3 Chimeric Antigen Receptor T Cells for Patients With Relapsed/Refractory Solid Tumors

PURPOSE

B7-H3 is an immunoregulatory protein overexpressed by many pediatric solid tumors with limited expression on critical organs, making it an attractive immunotherapy target. We present a first-in-human phase I clinical trial systemically administered B7-H3 chimeric antigen receptor (CAR) T cells for young patients with relapsed or refractory solid tumors.

PATIENTS AND METHODS

Patients were enrolled onto a phase I trial to examine the safety of B7-H3-specific CARs at various dose levels (DLs) using a standard 3 + 3 dose escalation design.

RESULTS

Sixteen patients (range, 11-24 years; median, 18.5 years) were enrolled, and nine were treated at DL1 (0.5 × 106 CAR T cells/kg; n = 3) or DL2 (1 × 106 CAR T cells/kg; n = 6). There were no first infusion dose-limiting toxicities. Maximum first-infusion circulating CAR T cells detected in the peripheral blood were 4.98 cells/μL (range, 0-4.98 cells/μL) with detection of CAR T cells colocalizing with tumor cells at the site of metastatic disease in one patient. Patients were eligible for subsequent infusions. An objective partial response by PERCIST criteria was observed 28 days after a second CAR T cell infusion in a patient who did not have an objective response after the first infusion. The second infusion demonstrated marked enhancement of CAR T cell expansion to 1,590 cells/μL and was accompanied by cytokine release syndrome and dose-limiting transaminitis. Detailed peripheral blood cytokine profiling revealed elevated IL-21 levels preinfusion 2 compared with infusion 1.

CONCLUSION

B7-H3 CAR T cells are tolerable and demonstrate limited antitumor activity without acute on-target, off-tumor toxicity. High levels of CAR T cell expansion may be necessary to achieve objective responses, but undefined host and tumor microenvironment factors appear to be critical (ClinicalTrials.gov identifier: NCT04483778).

Advances in breast cancer treatment: a systematic review of preoperative stereotactic body radiotherapy (SBRT) for breast cancer

Breast conserving treatment typically involves surgical excision of tumor and adjuvant radiotherapy targeting the breast area or tumor bed. Accurately defining the tumor bed is challenging and lead to irradiation of greater volume of healthy tissues. Preoperative stereotactic body radiotherapy (SBRT) which target tumor may solves that issues. We conducted a systematic literature review to evaluates the early toxicity and cosmetic outcomes of this promising treatment approach. Secondary we reviewed pathological complete response (pCR) rates, late toxicity, patient selection criteria and radiotherapy protocols. We retrieved literature from PubMed, Scopus, Web of Science, Cochrane, ScienceDirect, and ClinicalTrials.gov. The study adhered to the PRISMA 2020 guidelines. Ten prospective clinical trials (7 phase II, 3 phase I), encompassing 188 patients (aged 18-75 years, cT1-T3 cN0-N3 cM0, primarily with ER/PgR-positive, HER2-negative status,), were analyzed. Median follow-up was 15 months (range 3-30). Treatment involved single-fraction SBRT (15-21Gy) in five studies and fractionated (19.5-31.5Gy in 3 fractions) in the rest. Time interval from SBRT to surgery was 9.5 weeks (range 1-28). Acute and late G2 toxicity occurred in 0-17% and 0-19% of patients, respectively, G3 toxicity was rarely observed. The cosmetic outcome was excellent in 85-100%, fair in 0-10% and poor in only 1 patient. pCR varied, showing higher rates (up to 42%) with longer intervals between SBRT and surgery and when combined with neoadjuvant systemic therapy (up to 90%). Preoperative SBRT significantly reduce overall treatment time, enabling to minimalize volumes. Early results indicate excellent cosmetic effects and low toxicity.

Combining Metabolomics and Machine Learning to Identify Diagnostic and Prognostic Biomarkers in Patients with Non-Small Cell Lung Cancer Pre- and Post-Radiation Therapy

Lung cancer is the leading cause of cancer-related deaths globally, with non-small cell lung cancer (NSCLC) accounting for over 85% of cases and poor prognosis in advanced stages. This study explored shifts in circulating metabolite levels in NSCLC patients versus healthy controls and examined the effects of conventionally fractionated radiation therapy (CFRT) and stereotactic body radiation therapy (SBRT). We enrolled 91 NSCLC patients (38 CFRT and 53 SBRT) and 40 healthy controls. Plasma metabolite levels were assessed using semi-targeted metabolomics, revealing 32 elevated and 18 reduced metabolites in patients. Key discriminatory metabolites included ethylmalonic acid, maltose, 3-phosphoglyceric acid, taurine, glutamic acid, glycocolic acid, and d-arabinose, with a combined Receiver Operating Characteristics curve indicating perfect discrimination between patients and controls. CFRT and SBRT affected different metabolites, but both changes suggested a partial normalization of energy and amino acid metabolism pathways. In conclusion, metabolomics identified distinct metabolic signatures in NSCLC patients with potential as diagnostic biomarkers. The differing metabolic responses to CFRT and SBRT reflect their unique therapeutic impacts, underscoring the utility of this technique in enhancing NSCLC diagnosis and treatment monitoring.

Durable complete response to PET-CT driven stereotactic radiation therapy plus pembrolizumab for pleomorphic Pancoast cancer: Case report and literature review

PET-driven SBRT plus pembrolizumab as first-line therapy against pleomorphic Pancoast cancer appears beneficial, probably due to high equivalent doses of SBRT on photopenic necrotic core and synergic immune system stimulation of immunoradiotherapy.

Therapeutic In Situ Cancer Vaccine Using Pulsed Stereotactic Body Radiotherapy-A Translational Model

Both radiation and cancer therapeutic vaccine research are more than 100 years old, and their potential is likely underexplored. Antiangiogenics, nanoparticle targeting, and immune modulators are some other established anticancer therapies. In the meantime, immunotherapy usage is gaining momentum in clinical applications. This article proposes the concept of a pulsed/intermittent/cyclical endothelial-sparing single-dose in situ vaccination (ISVRT) schedule distinguishable from the standard therapeutic stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) plans. This ISVRT schedule can repeatedly generate tumor-specific neoantigens and epitopes for primary and immune modulation effects, augment supplementary immune enhancement techniques, activate long-term memory cells, avoid extracellular matrix fibrosis, and essentially synchronize with the vascular normalized immunity cycle. The core mechanisms of ISVRT impacting in situ vaccination would be optimizing cascading antigenicity and adjuvanticity. The present proposed hypothesis can be validated using the algorithm presented. The indications for the proposed concept are locally progressing/metastatic cancers that have failed standard therapies. Immunotherapy/targeted therapy, chemotherapy, antiangiogenics, and vascular-lymphatic normalization are integral to such an approach.

Multi-omics integrative modelling for stereotactic body radiotherapy in early-stage non-small cell lung cancer: clinical trial protocol of the MONDRIAN study

BACKGROUND

Currently, main treatment strategies for early-stage non-small cell lung cancer (ES-NSCLC) disease are surgery or stereotactic body radiation therapy (SBRT), with successful local control rates for both approaches. However, regional and distant failure remain critical in SBRT, and it is paramount to identify predictive factors of response to identify high-risk patients who may benefit from more aggressive approaches. The main endpoint of the MONDRIAN trial is to identify multi-omic biomarkers of SBRT response integrating information from the individual fields of radiomics, genomics and proteomics.

METHODS

MONDRIAN is a prospective observational explorative cohort clinical study, with a data-driven, bottom-up approach. It is expected to enroll 100 ES-NSCLC SBRT candidates treated at an Italian tertiary cancer center with well-recognized expertise in SBRT and thoracic surgery. To identify predictors specific to SBRT, MONDRIAN will include data from 200 patients treated with surgery, in a 1:2 ratio, with comparable clinical characteristics. The project will have an overall expected duration of 60 months, and will be structured into five main tasks: (i) Clinical Study; (ii) Imaging/ Radiomic Study, (iii) Gene Expression Study, (iv) Proteomic Study, (v) Integrative Model Building.

DISCUSSION

Thanks to its multi-disciplinary nature, MONDRIAN is expected to provide the opportunity to characterize ES-NSCLC from a multi-omic perspective, with a Radiation Oncology-oriented focus. Other than contributing to a mechanistic understanding of the disease, the study will assist the identification of high-risk patients in a largely unexplored clinical setting. Ultimately, this would orient further clinical research efforts on the combination of SBRT and systemic treatments, such as immunotherapy, with the perspective of improving oncological outcomes in this subset of patients.

TRIAL REGISTRATION

The study was prospectively registered at clinicaltrials.gov (NCT05974475).

Individualising radiation therapy decisions in breast cancer patients based on tumour infiltrating lymphocytes and genomic biomarkers

Radiation therapy (RT) has long been fundamental for the curative treatment of breast cancer. While substantial progress has been made in the anatomical and technological precision of RT delivery, and some approaches to de-escalate or omit RT based on clinicopathologic features have been successful, there remain substantial opportunities to refine individualised RT based on tumour biology. A major area of clinical and research interest is to ascertain the individualised risk of loco-regional recurrence to direct treatment decisions regarding escalation and de-escalation of RT. Patient-tailored treatment with RT is considerably lagging behind compared with the massive progress made in the field of personalised medicine that currently mainly applies to decisions on the use of systemic therapy or targeted agents. Herein we review select literature surrounding the use of tumour genomic biomarkers and biomarkers of the immune system, including tumour infiltrating lymphocytes (TILs), within the management of breast cancer, specifically as they relate to progress in moving toward analytically validated and clinically tested biomarkers utilized in RT.

The 2022 Assisi Think Tank Meeting: White paper on optimising radiation therapy for breast cancer

The present white paper, referring to the 4th Assisi Think Tank Meeting on breast cancer, reviews state-of-the-art data, on-going studies and research proposals. <70% agreement in an online questionnaire identified the following clinical challenges: 1: Nodal RT in patients who have a) 1-2 positive sentinel nodes without ALND (axillary lymph node dissection); b) cN1 disease transformed into ypN0 by primary systemic therapy and c) 1-3 positive nodes after mastectomy and ALND. 2. The optimal combination of RT and immunotherapy (IT), patient selection, IT-RT timing, and RT optimal dose, fractionation and target volume. Most experts agreed that RT- IT combination does not enhance toxicity. 3: Re-irradiation for local relapse converged on the use of partial breast irradiation after second breast conserving surgery. Hyperthermia aroused support but is not widely available. Further studies are required to finetune best practice, especially given the increasing use of re-irradiation.

Immunotherapy and Radiotherapy as an Antitumoral Long-Range Weapon-A Partnership with Unsolved Challenges: Dose, Fractionation, Volumes, Therapeutic Sequence

Immunotherapy, the modern oncological treatment with immune checkpoint inhibitors (ICIs), has been part of the clinical practice for malignant melanoma for more than a decade. Anti-cytotoxic T-lymphocyte antigen 4 (CTLA4), anti-programmed cell death Protein 1 (PD-1), or anti programmed death-ligand 1 (PD-L1) agents are currently part of the therapeutic arsenal of metastatic or relapsed disease in numerous cancers; more recently, they have also been evaluated and validated as consolidation therapy in the advanced local stage. The combination with radiotherapy, a treatment historically considered loco-regional, changes the paradigm, offering-via synergistic effects-the potential to increase immune-mediated tumor destruction. However, the fragile balance between the tumoricidal effects through immune mechanisms and the immunosuppression induced by radiotherapy means that, in the absence of ICI, the immune-mediated potentiation effect of radiotherapy at a distance from the site of administration is rare. Through analysis of the preclinical and clinical data, especially the evidence from the PACIFIC clinical trial, we can consider that hypofractionated irradiation and reduction of the irradiated volume, in order to protect the immune-infiltrated tumor microenvironment, performed concurrently with the immunotherapy or a maximum of 2 weeks before the start of ICI treatment, could bring maximum benefits. In addition, avoiding radiation-induced lymphopenia (RILD) by protecting some anatomical lymphoid structures or large blood vessels, as well as the use of irradiation of partial tumor volumes, even in plurimetastatic disease, for the conversion of a "cold" immunological tumor into a "hot" immunological tumor are modern concepts of radiotherapy in the era of immunotherapy. Low-dose radiotherapy could also be proposed in plurimetastatic cases, the effect being different (modeling of the TME) from that of high doses per fraction irradiation (cell death with release of antigens that facilitates immune-mediated cell death).

The Evolving Interplay of SBRT and the Immune System, along with Future Directions in the Field

Simple Summary

We provide this commentary of stereotactic body radiotherapy (SBRT), and describe our evolving understanding of this treatment approach, its effects on the immune system, and the ability to stimulate immune cells to further recognize and attack cancer. The aim of this work is to describe our current knowledge of how SBRT effects the environment within the tumor and the immune cells present, whether timing the combination of this treatment with that of immunotherapy may have an impact on the body’s own immune response, and what the latest approaches in the field are in regards to this radiation treatment modality. Among these latest and exciting developments is Personalized Ultrafractionated Stereotactic Adaptive Radiation Therapy, known as PULSAR. This latest approach is described in detail herein, and may represent a leading novel method for adapting radiation treatments to treatment-induced tumor changes over time and stimulating the body’s immune response against tumor cells.

Abstract

In this commentary, we describe the potential of highly ablative doses utilizing Stereotactic Body Radiation Therapy (SBRT) in single or few fractions to enhance immune-responsiveness, how timing of this approach in combination with immune-checkpoint inhibitors may augment treatment-effect, and whether Personalized Ultrafractionated Stereotactic Adaptive Radiation Therapy (PULSAR) is an avenue for future advancement in the continued endeavor to foster a systemic effect of therapy beyond the radiation treatment field. The ablative potential of SBRT may support an increase in tumor-antigen presentation, enhancement of immune-stimulatory components, and an improvement in tumor-microenvironment immune cell infiltration. Furthermore, the latest advancement of ablative radiation delivery is PULSAR-based therapy, whereby ablative doses are delivered in pulses of treatment that may be several weeks apart, combined with adaptive treatment to tumor changes across time. The benefits of this novel approach include the ability to optimize direct tumor control by assessment of tumor size and location via dedicated imaging acquired prior to each delivered pulse, and further potentiation of immune recognition through combination with concurrent immune-checkpoint blockade.