Radiological evaluation of response to immunotherapy in brain tumors: Where are we now and where are we going?

A review of immune checkpoint blockade in breast cancer

In the recent years characterized by the cancer immunotherapy revolution, attention has turned to how to potentially boost and/or generate an efficient anti-tumor immune response in breast cancer (BC). Clinical activity of immune checkpoint blockade (ICB) targeting PD-1 or PD-L1 in BC has been more evident in the triple negative subtype and in earlier lines of the treatment. Remarkably, some responders to single agent ICB have achieved durable responses with metastatic disease, possibly as a result of treatment-induced immunological memory. However, most BC are immunologically quiescent and current research efforts developing ICB combinations are attempting to convert "cold" into "hot" tumors by manipulating the tumor microenvironment, expanding anti-tumor T cells improving efficient antigen presentation, and suppressing pro-tumor inhibitory cells. The aim of this review is to summarize existing data on the efficacy of immune checkpoint blockers as single agents and combination strategies in all BC subtypes, highlighting the BC subgroups that benefit most from ICB.

Luminal Breast Cancer: Risk of Recurrence and Tumor-Associated Immune Suppression

Hormone-receptor positive (HR+) breast cancer (BC) (including the luminal A and the luminal B subtypes) is the most common type of tumor in women diagnosed with early-stage BC (EBC). It represents a highly heterogeneous subgroup that is characterized by different risks of relapse. The aim of this review is to discuss the possible role played by the immune response in predicting this risk, along with the most common clinical and pathological factors and molecular tools that have been developed and are already in use. As opposed to what has previously been observed in the most aggressive human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer (TNBC) subtypes, a high proportion of tumor-infiltrating lymphocytes (TILs)-reflecting a spontaneous and pre-existing immune response to the tumor-has been linked to a worse prognosis in HR+ EBC. This work provides some immune biological rationale explaining these findings and provides the basics to understand the principal clinical trials that are testing immunotherapy in HR+ (luminal) BC.

The rationale behind targeting the ICOS-ICOS ligand costimulatory pathway in cancer immunotherapy

Inducible T cell costimulator (ICOS, cluster of differentiation (CD278)) is an activating costimulatory immune checkpoint expressed on activated T cells. Its ligand, ICOSL is expressed on antigen-presenting cells and somatic cells, including tumour cells in the tumour microenvironment. ICOS and ICOSL expression is linked to the release of soluble factors (cytokines), induced by activation of the immune response. ICOS and ICOSL binding generates various activities among the diversity of T cell subpopulations, including T cell activation and effector functions and when sustained also suppressive activities mediated by regulatory T cells. This dual role in both antitumour and protumour activities makes targeting the ICOS/ICOSL pathway attractive for enhancement of antitumour immune responses. This review summarises the biological background and rationale for targeting ICOS/ICOSL in cancer together with an overview of the principal ongoing clinical trials that are testing it in combination with anti-cytotoxic T lymphocyte antigen-4 and anti-programmed cell death-1 or anti-programmed cell death ligand-1 based immune checkpoint blockade.

Immune Checkpoint Inhibitor-Induced Pancreatic Injury: Imaging Findings and Literature Review

The immunotherapy revolution in cancer treatment involves a variety of specialists, not only oncologists, but also internal medicine physicians, endocrinologists, dermatologists, gastroenterologists, rheumatologists, and radiologists, introducing new scenarios and novel challenges in the diagnosis and management of a number of novel immune-related adverse events. Among these, immune checkpoint inhibitor-induced pancreatic injury has been described (occurring in up to 4% of patients) and has been reported to be responsible for visits to the emergency departments in up to 1.9% of patients treated with immune checkpoint inhibitors. This side effect can be symptomatic or non-symptomatic, and can be associated with the development of long-term damage to the pancreas, requiring the involvement of different specialists, including radiologists and gastroenterologists in the multidisciplinary team that manages these patients. The aim of this narrative review is to provide a summary of the available literature related to immune checkpoint inhibitor-induced pancreatic injury including the epidemiology, the clinical findings, and the management algorithm for diagnosis with a detailed analysis of the differential diagnosis at imaging, and treatment. A more in-depth focus is dedicated to symptomatic acute pancreatitis with its peculiar findings at imaging (ultrasound, computed tomography, and magnetic resonance imaging).

Programmed cell death-ligand 2: A neglected but important target in the immune response to cancer?

Programmed cell death-ligand 2 (PD-L2) is one of the two ligands of the programmed cell death-1 (PD-1) receptor, an inhibitory protein mainly expressed on activated immune cells that is targeted in the clinic, with successful and remarkable results. The PD-1/PD-Ls axis was shown to be one of the most relevant immunosuppressive pathways in the immune microenvironment, and blocking this interaction gave rise to an impressive clinical benefit in a broad variety of solid and hematological malignancies. Although PD-L2 has been historically considered a minor ligand, it binds to PD-1 with a two- to six-fold higher affinity as compared to PD-L1. PD-L2 can be expressed by immune, stromal, or tumor cells. The aims of this narrative review are to summarize PD-L2 biology in the physiological responses of the immune system and its role, expression, and clinical significance in cancer.

Radiomics and "radi-…omics" in cancer immunotherapy: a guide for clinicians

In recent years the concept of precision medicine has become a popular topic particularly in medical oncology. Besides the identification of new molecular prognostic and predictive biomarkers and the development of new targeted and immunotherapeutic drugs, imaging has started to play a central role in this new era. Terms such as "radiomics", "radiogenomics" or "radi…-omics" are becoming increasingly common in the literature and soon they will represent an integral part of clinical practice. The use of artificial intelligence, imaging and "-omics" data can be used to develop models able to predict, for example, the features of the tumor immune microenvironment through imaging, and to monitor the therapeutic response beyond the standard radiological criteria. The aims of this narrative review are to provide a simplified guide for clinicians to these concepts, and to summarize the existing evidence on radiomics and "radi…-omics" in cancer immunotherapy.

Excision Repair Cross Complementation Group 1 Single Nucleotide Polymorphisms and Nivolumab in Advanced Non-Small Cell Lung Cancer

Background: We hypothesized that non-small cell lung cancer (NSCLC) patients with a tumor positive for single nucleotide polymorphisms (SNPs) of the Excision Repair Cross Complementation Group 1 (ERCC-1) gene could be more genetically instable and consequently more responsive to a programmed cell death-1 (PD-1) blockade.

Methods: We evaluated the T19007C and C8092A ERCC-1 SNPs by pyrosequencing assay, on tumor specimens from two independent cohorts of patients who relapsed after one or more prior systemic treatments for advanced NSCLC and who received nivolumab (3 mg/kg intravenously every 2 weeks) as part of the Italian Expanded Access Program. We aimed to assess the outcome of enrolled subjects according to the ERCC-1 SNPs status, to evaluate the role of these polymorphisms as putative biomarkers associated with a response/clinical benefit to anti-PD-1 therapies.

Results: Of the 45 patients included in the final analysis, 21 (47%) and 16 (36%) were positive for the T19007C and C8092A polymorphic genotype (PG), respectively. In univariate analyses, overall survival (OS) and progression free survival (PFS) were shorter in patients with the T19007C PG, but neither difference achieved statistical significance (P = 0.131 and P = 0.717, respectively). The presence of the C8092A PG was associated with a longer OS and PFS, although statistical significance was only reached for PFS (P = 0.112 and P = 0.025, respectively). These results were confirmed by multivariate analyses. The response rate was only significantly higher in patients with the C8092A PG vs. wild type ERCC-1 (62 vs. 7%, P < 0.001).

Conclusions: Results from this hypothesis generating pilot study, provided suggestive evidence that a subgroup of NSCLC patients could benefit differently from nivolumab according to the C8092A ERCC-1 SNP status. However, these data warrant further investigation.

Cancer Imaging in Immunotherapy

Immune therapeutics are revolutionizing cancer treatments. In tandem, new and confounding imaging characteristics have appeared that are distinct from those typically seen with conventional cytotoxic therapies. In fact, only 10% of patients on immunotherapy may show tumor shrinkage, typical of positive responses on conventional therapy. Conversely, those on immune therapies may initially demonstrate a delayed response, transient enlargement followed by tumor shrinkage, stable size, or the appearance of new lesions. New imaging response criteria, such as the immune-related Response Evaluation Criteria in Solid Tumors (irRECIST) and immune-related Response Criteria (irRC), are being implemented in many trials. However, FDA approval of emerging therapies, including immunotherapies, still relies on the current RECIST criteria. In this chapter, we review the traditional and new imaging response criteria for evaluation of solid tumors and briefly touch on some of the more commonly associated immunotherapy-induced adverse events.

Current and Future Imaging Methods for Evaluating Response to Immunotherapy in Neuro-Oncology

Imaging plays a central role in evaluating responses to therapy in neuro-oncology patients. The advancing clinical use of immunotherapies has demonstrated that treatment-related inflammatory responses mimic tumor growth via conventional imaging, thus spurring the development of new imaging approaches to adequately distinguish between pseudoprogression and progressive disease. To this end, an increasing number of advanced imaging techniques are being evaluated in preclinical and clinical studies. These novel molecular imaging approaches will serve to complement conventional response assessments during immunotherapy. The goal of these techniques is to provide definitive metrics of tumor response at earlier time points to inform treatment decisions, which has the potential to improve patient outcomes. This review summarizes the available immunotherapy regimens, clinical response criteria, current state-of-the-art imaging approaches, and groundbreaking strategies for future implementation to evaluate the anti-tumor and immune responses to immunotherapy in neuro-oncology applications.