Radiologic manifestations of immune-related adverse events in patients with metastatic melanoma undergoing anti-CTLA-4 antibody therapy

Sarcoidosis-like reactions in metastatic renal cell carcinoma patients treated with immune-based combinations

Aim: The incidence of drug-induced sarcoidosis-like reactions (DISR) in patients treated with immune checkpoint inhibitors (ICIs) is rising. We determine the incidence and characteristics of DISR in a metastatic renal cell carcinoma (mRCC) population. Methods: We retrospectively reviewed clinico-radiological data of 83 mRCC patients treated at a single institution with immune-based combinations. Results: 15 patients received immune-doublet (ipilimumab-nivolumab), while 68 patients received other immune-based combinations. Two cases of DISR (2.4%) were evidenced, with enlargement of mediastinal lymph nodes that mimicked disease progression, thus requiring a biopsy which showed histological features of DISR. Conclusion: In our series of the incidence of DISR, radiological and clinical features, are in line with literature. DISR diagnosis is often only radiological, and its occurrence is possibly associated with a better outcome.

PET/CT in Inflammatory and Auto-immune Disorders: Focus on Several Key Molecular Concepts, FDG, and Radiolabeled Probe Perspectives

Chronic immune diseases mainly include autoimmune and inflammatory diseases. Managing chronic inflammatory and autoimmune diseases has become a significant public health concern, and therapeutic advancements over the past 50 years have been substantial. As therapeutic tools continue to multiply, the challenge now lies in providing each patient with personalized care tailored to the specifics of their condition, ushering in the era of personalized medicine. Precise and holistic imaging is essential in this context to comprehensively map the inflammatory processes in each patient, identify prognostic factors, and monitor treatment responses and complications. Imaging of patients with inflammatory and autoimmune diseases must provide a comprehensive view of the body, enabling the whole-body mapping of systemic involvement. It should identify key cellular players in the pathology, involving both innate immunity (dendritic cells, macrophages), adaptive immunity (lymphocytes), and microenvironmental cells (stromal cells, tissue cells). As a highly sensitive imaging tool with vectorized molecular probe capabilities, PET/CT can be of high relevance in the management of numerous inflammatory and autoimmune diseases. Relying on key molecular concepts of immunity, the clinical usefulness of FDG-PET/CT in several relevant inflammatory and immune-inflammatory conditions, validated or emerging, will be discussed in this review, together with radiolabeled probe perspectives.

Radiological assessment of immunotherapy effects and immune checkpoint-related pneumonitis for lung cancer

Immune checkpoint inhibitors (ICIs) therapy have revolutionized advanced lung cancer care. Interestingly, the host responses for patients received ICIs therapy are distinguishing from those with cytotoxic drugs, showing potential initial transient worsening of disease burden, pseudoprogression and delayed time to treatment response. Thus, a new imaging criterion to evaluate the response for immunotherapy should be developed. ICIs treatment is associated with unique adverse events, including potential life-threatening immune checkpoint inhibitor-related pneumonitis (ICI-pneumonitis) if treated patients are not managed promptly. Currently, the diagnosis and clinical management of ICI-pneumonitis remain challenging. As the clinical manifestation is often nonspecific, computed tomography (CT) scan and X-ray films play important roles in diagnosis and triage. This article reviews the complications of immunotherapy in lung cancer and illustrates various radiologic patterns of ICI-pneumonitis. Additionally, it is tried to differentiate ICI-pneumonitis from other pulmonary pathologies common to lung cancer such as radiation pneumonitis, bacterial pneumonia and coronavirus disease of 2019 (COVID-19) infection in recent months. Maybe it is challenging to distinguish radiologically but clinical presentation may help.

Granulomatous and Sarcoid-like Immune-Related Adverse Events following CTLA4 and PD1 Blockade Adjuvant Therapy of Melanoma: A Combined Analysis of ECOG-ACRIN E1609 and SWOG S1404 Phase III Trials and a Literature Review

BACKGROUND

Treatment with immune checkpoint inhibitors (ICIs) has been linked to granulomatous and sarcoid-like lesions (GSLs) affecting different organs. This study sought to evaluate GSL incidence in patients with high-risk melanoma treated with cytotoxic T-lymphocyte antigen 4 (CTLA4) or programmed cell death 1 (PD1) blockade adjuvant therapy in two clinical trials: ECOG-ACRIN E1609 and SWOG S1404. Descriptions and GSL severity ratings were recorded.

METHODS

Data were collected from ECOG-ACRIN E1609 and SWOG S1404. Descriptive statistics along with GSL severity grades were reported. Additionally, a literature review for such cases was summarized.

RESULTS

A total of 11 GSL cases were reported among 2878 patients treated with either ICI or with High-Dose Interferon Alfa-2b (HDI) in ECOG-ACRIN E1609 and SWOG S1404 trials. Cases were numerically more commonly reported with ipi10, followed by pembrolizumab, ipi3, and HDI, respectively. Most of the cases were grade III. Further, organs involved included lung, mediastinal lymph nodes, skin and subcutaneous tissue, and eye. Furthermore, a summary of 62 reports in the literature was described.

CONCLUSIONS

GSLs following anti-CTLA4 and anti-PD1 antibody therapy in patients with melanoma were reported unusually. Reported cases ranged in grade from I to III and appeared manageable. Careful attention to these events and their reporting will be essential to better guide practice and management guidelines.

Retroperitoneal Inflammation Detected on FDG PET/CT in Patient on Long-Term Immunotherapy

ABSTRACT

A 68-year-old man with a history of pulmonary adenocarcinoma on maintenance pembrolizumab presented for surveillance imaging. 18 F-FDG PET/CT demonstrated new ill-defined right retroperitoneal and presacral soft tissue stranding with associated FDG uptake suggestive of inflammation. Biopsy results revealed fibroadipose tissue with extensive lymphoplasmacytic inflammation concerning for immunotherapy-related toxicity. The patient was subsequently taken off pembrolizumab, which he had been on for approximately 3 years. Recognition of immunotherapy-related adverse effects and how they can manifest on 18 F-FDG PET/CT is important for prompt cessation of treatment.

Rheumatic Diseases Development in Patients Treated by Anti-PD1 Immune Checkpoint Inhibitors: A Single-Centre Descriptive Study

The introduction of the so-called immune checkpoint inhibitors (ICIs) substantially changed the history of cancer therapy. On the other hand, they can induce the development of rheumatic immune-related adverse events (Rh-irAEs). In the scenario of a joint oncology/rheumatology outpatient clinic, we conducted a single-centre descriptive study to define from a laboratory, clinical and therapeutic point of view, rheumatic conditions developed during anti-PD1 treatment. The study included 32 patients (M/F 16/16, median age 69, IQR 16.5). According to the international classification criteria, eight patients could be classified as affected by Rheumatoid Arthritis, one by Psoriatic Arthritis, six by Polymyalgia Rheumatica, five by systemic connective tissue diseases (two systemic lupus erythematosus, two Sjögren’s syndrome, one undifferentiated connective tissue disease). The remaining patients were diagnosed as having undifferentiated arthritis or inflammatory arthralgia. The median interval between ICIs starting and the onset of symptoms was 14 weeks (IQR 19.75). Moving to treatment, the longitudinal observation revealed that all RA, PsA and CTD patients required the introduction of treatment with DMARDs. In conclusion, the growing use of ICIs in a real-life setting confirmed the possible development of different rheumatological conditions, further emphasising the need for shared oncology/rheumatology management.

FDG PET/CT in Immune-Related Arthritis in a Patient Treated With Nivolumab

ABSTRACT

Immune checkpoint inhibitors are a new and different treatment option in many of solid tumors, but with many recognized immune-related adverse side effects. In this interesting image, we are presenting a 56-year-old woman with primary malignant melanoma who underwent nivolumab therapy for 5 months, and a posttreatment whole-body FDG PET/CT scan for treatment response evaluation demonstrated increased metabolic activity in the entire major joints of the upper and lower extremities. This was a new finding compared with previous FDG PET/CT scan and was interpreted as an immune-related arthritis complication.

Radiation Recall Pneumonitis: The Open Challenge in Differential Diagnosis of Pneumonia Induced by Oncological Treatments

The treatment of primary and secondary lung neoplasms now sees the fundamental role of radiotherapy, associated with surgery and systemic therapies. The improvement in survival outcomes has also increased attention to the quality of life, treatment compliance and the management of side effects. The role of imaging is not only limited to recognizing the efficacy of treatment but also to identifying, as soon as possible, the uncommon effects, especially when more treatments, such as chemotherapy, immunotherapy and radiotherapy, are associated. Radiation recall pneumonitis is an uncommon treatment complication that should be correctly characterized, and it is essential to recognize the mechanisms of radiation recall pneumonitis pathogenesis and diagnostic features in order to promptly identify them and adopt the best therapeutic strategy, with the shortest possible withdrawal of the current oncological drug. In this setting, artificial intelligence could have a critical role, although a larger patient data set is required.

Retrospective study of the incidence of sarcoidosis-like reaction in patients treated with immunotherapy

AIM

To assess the frequency of radiographically evident drug-induced sarcoidosis-like reaction (DISR) in patients treated with anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) therapy, anti-programmed cell death protein 1 (PD-1) therapy, or a combination of both in a single centre.

MATERIALS AND METHODS

The images and medical records of 457 patients with metastatic melanoma or head and neck cancer treated with either anti-CTLA-4 therapy, anti-PD-1 therapy, or a combination of both at University of California medical centre were reviewed retrospectively and the incidence of radiological manifestations of DISR was assessed among these treatment groups.

RESULTS

Radiological manifestations of DISR were found in 19/457 patients (4.1%). The mean interval from the initiation of immunotherapy to development of DISR was 5.5 months (range 2.3-13.5 months). Mean interval from radiological detection of DISR to imaging evidence of resolution was 5.8 months (range 1.6-18.3 months). Three patients out of 81 (3.7%), 11/297 (3.7%), and 5/79 (6.3%) developed sarcoidosis-like reaction after treatment with anti-CTLA-4 antibody, anti-PD-1 antibody, and a combination of both, respectively. Most patients with DISR were asymptomatic and did not require systemic therapy. Most patients did not demonstrate concomitant increased maximum standardised uptake value (SUVmax) in other organs on their integrated 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT).

CONCLUSIONS

In the present retrospective study of patients treated with immune checkpoint inhibitors (ICIs), DISR occurred in approximately 3.7% of patients treated with either anti-CTLA-4 or anti-PD-1 antibody and 6.3% of patients treated with a combination of both.

Immune-Related Thyroiditis in Patients with Advanced Lung Cancer Treated with Immune Checkpoint Inhibitors: Imaging Features and Clinical Implications

Immune checkpoint inhibitors (ICI) are widely used in advanced nonsmall cell lung cancer (NSCLC) treatment, and the immune-related adverse events involving many organs have been recognized. This article investigated the incidence and imaging characteristics of immune-related thyroiditis in NSCLC patients and correlated the findings with clinical features. A total of 534 NSCLC patients treated with ICI were included. Imaging findings indicative of thyroiditis included changes in morphology and attenuation on restaging chest CT scans and FDG uptake on PET/CT during ICI therapy. Fifty patients (9.4%) had imaging findings indicative of thyroiditis. The median time to onset was 9.5 weeks (range: 0.9-87.4 weeks). The most common finding was diffuse hypoattenuation of the gland (72%), with enlargement in 15 and atrophy in 12 patients. Heterogeneous attenuation of the gland was noted in 12 patients (24%), with enlargement in 7 and atrophy in 1 patient. Two patients (4%) showed increased FDG uptake in the gland on PET/CT without changes in the CT scan. Twenty-two patients who had both clinical and radiologic diagnoses of thyroiditis were more frequently managed with hormone replacement than those with thyroiditis without an imaging abnormality (p < 0.0001). Therefore, awareness of the imaging findings of immune-related thyroiditis may alert clinicians to the presence of clinically relevant thyroiditis.

Rheumatoid Arthritis Symptoms Diagnosed by Rheumatic Immune-related Adverse Events Caused by Nivolumab in a Patient with Esophageal Cancer

This report described the case of a 70-year-old man who developed polyarthralgia after nivolumab treatment for recurrent esophageal cancer. Arthritis developed after initiating nivolumab therapy, and the patient tested positive for rheumatoid factor and anti-citrullinated peptide antibodies. The hand and elbow joints were already deformed, suggesting that he had had rheumatoid arthritis for several years and that the symptoms had only become apparent after nivolumab administration. This patient had rheumatoid arthritis, which was diagnosed as a nivolumab-induced rheumatic immune-related adverse event (rh-irAEs). Arthralgia during nivolumab administration can occur in rh-irAE cases. Patients should be assessed for autoimmune diseases before initiating immune checkpoint inhibitors.

Positron emission tomography molecular imaging to monitor anti-tumor systemic response for immune checkpoint inhibitor therapy

Immune checkpoint inhibitors (ICIs) achieve a milestone in cancer treatment. Despite the great success of ICI, ICI therapy still faces a big challenge due to heterogeneity of tumor, and therapeutic response is complicated by possible immune-related adverse events (irAEs). Therefore, it is critical to assess the systemic immune response elicited by ICI therapy to guide subsequent treatment regimens. Positron emission tomography (PET) molecular imaging is an optimal approach in cancer diagnosis, treatment effect evaluation, follow-up, and prognosis prediction. PET imaging can monitor metabolic changes of immunocytes and specifically identify immuno-biomarkers to reflect systemic immune responses. Here, we briefly review the application of PET molecular imaging to date of systemic immune responses following ICI therapy and the associated rationale.

Imaging assessment of toxicity related to immune checkpoint inhibitors

In recent years, a wide range of cancer immunotherapies have been developed and have become increasingly important in cancer treatment across multiple oncologic diseases. In particular, immune checkpoint inhibitors (ICIs) offer promising options to improve patient outcomes. However, a major limitation of these treatments consists in the development of immune-related adverse events (irAEs) occurring in potentially any organ system and affecting up to 76% of the patients. The most frequent toxicities involve the skin, gastrointestinal tract, and endocrine system. Although mostly manageable, potentially life-threatening events, particularly due to neuro-, cardiac, and pulmonary toxicity, occur in up to 30% and 55% of the patients treated with ICI-monotherapy or -combination therapy, respectively. Imaging, in particular computed tomography (CT), magnetic resonance imaging (MRI), and 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT), plays an important role in the detection and characterization of these irAEs. In some patients, irAEs can even be detected on imaging before the onset of clinical symptoms. In this context, it is particularly important to distinguish irAEs from true disease progression and specific immunotherapy related response patterns, such as pseudoprogression. In addition, there are irAEs which might be easily confused with other pathologies such as infection or metastasis. However, many imaging findings, such as in immune-related pneumonitis, are nonspecific. Thus, accurate diagnosis may be delayed underling the importance for adequate imaging features characterization in the appropriate clinical setting in order to provide timely and efficient patient management. ¹⁸F-FDG-PET/CT and radiomics have demonstrated to reliably detect these toxicities and potentially have predictive value for identifying patients at risk of developing irAEs. The purpose of this article is to provide a review of the main immunotherapy-related toxicities and discuss their characteristics on imaging.

Sarcoid-Like Granulomatosis of the Lung Related to Durvalumab After Chemoradiation for Pulmonary Squamous Cell Carcinoma

Sarcoid-like granulomatosis is a unique immune-related adverse event (irAE) in cancer patients treated with immune checkpoint inhibitors (ICIs). This irAE is infrequent, reported to range from 2% to 22.2% of melanoma treated with ICI. In a case of granulomatosis localized in the lung, it is difficult to differentiate granulomatosis from cancer progression or metastases. Herein, we report a case of ICI-induced sarcoid-like granulomatosis of the lung, which was confusable with localized recurrence of the primary lung cancer. A 56-year-old woman with c-stage IIIA of pulmonary squamous cell carcinoma in the right lower lobe received chemo-radiotherapy with two courses of cisplatin and vinorelbine and concurrent thoracic irradiation, followed by 1-year durvalumab consolidation therapy. The tumor in the right S₆ grew and presented abnormal uptake by fluorodeoxyglucose positron emission tomography (FDG-PET), 1.5 years after durvalumab. Neither computed tomography (CT) nor FDG-PET found mediastinal and distant metastases. She underwent right lower lobe lobectomy. Histopathologically, the tumor and sampled lymph nodes contained no residue of carcinoma cells but presented diffuse epithelioid granuloma with infiltration of inflammatory cells, partial necrotic lesions and many multinucleated giant cells. In immunohistochemical stains, CD3⁺ and CD8⁺ T cells predominantly infiltrated, while there were few CD4⁺ T cells and a small number of CD20⁺ B cells. We followed her without steroid and other immunosuppressant drug. We should pay attention to the development of sarcoid-like granulomatosis as a rare irAE, which is difficult to be differentiated from cancer progression.

Tumor response assessment on imaging following immunotherapy

In recent years, various systemic immunotherapies have been developed for cancer treatment, such as monoclonal antibodies (mABs) directed against immune checkpoints (immune checkpoint inhibitors, ICIs), oncolytic viruses, cytokines, cancer vaccines, and adoptive cell transfer. While being estimated to be eligible in 38.5% of patients with metastatic solid or hematological tumors, ICIs, in particular, demonstrate durable disease control across many oncologic diseases (e.g., in melanoma, lung, bladder, renal, head, and neck cancers) and overall survival benefits. Due to their unique mechanisms of action based on T-cell activation, response to immunotherapies is characterized by different patterns, such as progression prior to treatment response (pseudoprogression), hyperprogression, and dissociated responses following treatment. Because these features are not encountered in the Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), which is the standard for response assessment in oncology, new criteria were defined for immunotherapies. The most important changes in these new morphologic criteria are, firstly, the requirement for confirmatory imaging examinations in case of progression, and secondly, the appearance of new lesions is not necessarily considered a progressive disease. Until today, five morphologic (immune-related response criteria (irRC), immune-related RECIST (irRECIST), immune RECIST (iRECIST), immune-modified RECIST (imRECIST), and intra-tumoral RECIST (itRECIST)) criteria have been developed to accurately assess changes in target lesion sizes, taking into account the specific response patterns after immunotherapy. In addition to morphologic response criteria, 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is a promising option for metabolic response assessment and four metabolic criteria are used (PET/CT Criteria for Early Prediction of Response to Immune Checkpoint Inhibitor Therapy (PECRIT), PET Response Evaluation Criteria for Immunotherapy (PERCIMT), immunotherapy-modified PET Response Criteria in Solid Tumors (imPERCIST5), and immune PERCIST (iPERCIST)). Besides, there is evidence that parameters on 18F-FDG-PET/CT, such as the standardized uptake value (SUV)max and several radiotracers, e.g., directed against PD-L1, may be potential imaging biomarkers of response. Moreover, the emerge of human intratumoral immunotherapy (HIT-IT), characterized by the direct injection of immunostimulatory agents into a tumor lesion, has given new importance to imaging assessment. This article reviews the specific imaging patterns of tumor response and progression and available imaging response criteria following immunotherapy.

MRI techniques for immunotherapy monitoring

MRI is a widely available clinical tool for cancer diagnosis and treatment monitoring. MRI provides excellent soft tissue imaging, using a wide range of contrast mechanisms, and can non-invasively detect tissue metabolites. These approaches can be used to distinguish cancer from normal tissues, to stratify tumor aggressiveness, and to identify changes within both the tumor and its microenvironment in response to therapy. In this review, the role of MRI in immunotherapy monitoring will be discussed and how it could be utilized in the future to address some of the unique clinical questions that arise from immunotherapy. For example, MRI could play a role in identifying pseudoprogression, mixed response, T cell infiltration, cell tracking, and some of the characteristic immune-related adverse events associated with these agents. The factors to be considered when developing MRI imaging biomarkers for immunotherapy will be reviewed. Finally, the advantages and limitations of each approach will be discussed, as well as the challenges for future clinical translation into routine clinical care. Given the increasing use of immunotherapy in a wide range of cancers and the ability of MRI to detect the microstructural and functional changes associated with successful response to immunotherapy, the technique has great potential for more widespread and routine use in the future for these applications.

Anti-RA33 antibodies are present in a subset of patients with immune checkpoint inhibitor-induced inflammatory arthritis

OBJECTIVE

Patients with inflammatory arthritis (IA) associated with immune checkpoint inhibitor (ICI) treatment for cancer are typically seronegative for anti-cyclic citrullinated peptide (CCP) antibodies and rheumatoid factor, but little is known about the presence of other autoantibodies in this patient population. We investigated the prevalence and characteristics of anti-RA33 antibodies in patients with ICI-induced IA.

METHODS

Anti-RA33 ELISAs were performed on sera from four groups of patients: 79 with ICI-induced IA, 52 with rheumatoid arthritis (RA), 35 treated with ICIs without IA during follow-up and 50 healthy controls. Anti-RA33 positivity and level, clinical and demographic data were compared across groups.

RESULTS

Anti-RA33 antibodies were found in 9/79 (11.4%) patients with ICI-induced IA but in 0/35 patients treated with ICIs who did not develop IA (0%; p=0.04). Of the patients positive for anti-RA33, two had sera available from before ICI treatment; anti-RA33 antibodies were present in both pre-ICI treatments. In patients with RA, 7.7% were positive for anti-RA33 antibodies as were 2% of healthy controls. In ICI-induced IA, anti-RA33 antibodies were associated with anti-CCP antibodies (p=0.001). We found no statistically significant differences in other clinical characteristics in those with and without anti-RA33 antibodies.

CONCLUSIONS

Anti-RA33 antibodies are present in a subset of patients with ICI-induced IA, absent in other ICI-treated patients and may be a biomarker for developing IA. Additional studies evaluating serial samples before and after ICI treatment will further establish the temporal relationship of these antibodies to IA development.

Adverse effects under immune checkpoint inhibitors on [18F]FDG PET/CT imaging

Despite their undisputed contribution to the management of various tumors and the prolongation of patient survival, immune checkpoint inhibitors (ICIs) exert their effect at the cost of toxicity. In the context of the activation of the host immune system triggered by ICIs, collateral, inflammatory side effects, commonly addressed as immune-related adverse events (irAEs) often occur. Early detection of irAEs can be critical for adequate decisions on patient management that may subsequently improve patient outcome. Moreover, the emergence of irAEs has been linked with the antitumor effect elicited by ICIs, thus, their identification may potentially provide prognostic information. Although the diagnosis of irAEs is mainly clinical, some adverse events may be asymptomatic and only diagnosed by imaging modalities. At the same time, radiological signs of irAEs are not necessarily associated with clinical symptoms, however, clinicians should be alerted to their presence. Among imaging modalities [¹⁸F]FDG PET/CT has shown satisfying efficiency in response assessment and monitoring of ICIs' treatment, especially in patients suffering from metastatic melanoma and lung cancer. In this context, [¹⁸F]FDG PET/CT may also be a valuable method for surveillance of irAEs during immunotherapy. This article aims to review the most common adverse events observed on [¹⁸F]FDG PET/CT under immunotherapy and summarize potential results linking PET signs of irAEs with response assessment to ICIs.

Imaging Findings in Patients with Immune Checkpoint Inhibitor-Induced Arthritis

Immune checkpoint inhibitor (ICI)-induced arthritis is an increasingly recognized adverse event in patients with oncologic disease during immunotherapy. Four patterns are well described, including rheumatoid arthritis (RA)-like, polymyalgia rheumatica (PMR)-like, psoriatic arthritis (PsA)-like, and oligo-monoarthritis, among others. Despite better clinical recognition of these syndromes, information about the main imaging findings is limited. Methods: We conducted a retrospective observational study including all adult patients referred to the Rheumatology Department of a single-center due to ICI-induced arthritis who underwent imaging studies [ultrasound (US), magnetic resonance imaging (MRI), and ¹⁸F-FDG PET/CT)] between January 2017 and January 2022. Results: Nineteen patients with ICI-induced arthritis with at least one diagnostic imaging assessment were identified (15 US, 4 MRI, 2 ¹⁸F-FDG PET/CT). Most patients were male (84.2%), with a median age at inclusion of 73 years. The main underlying diagnoses for ICI treatment were melanoma in five cases. The distribution of ICI-induced arthritis was as follows: PMR-like (5, 26.2%), RA-like (4, 21.1%), PsA-like (4, 21.1%), and others (6, 31.6%). All RA-like patients had US findings indistinguishable from conventional RA patients. In addition, 3/5 (60%) of PMR-like patients had significant involvement of the hands and wrists. Abnormal findings on MRI or PET-CT were reported by clinical symptoms. No erosions or myofascitis were seen. Conclusions: ICI-induced arthritis patients present inflammatory patterns on imaging studies similar to conventional inflammatory arthropathies, and therefore these syndromes should be followed carefully and treated according to these findings.

Immunotherapy-induced granulomatous reaction in patients with melanoma

Immune checkpoint inhibitors (ICIs) represent a new era in stage IV melanoma treatment. These agents are generally well tolerated but have specific side effects. The granulomatous reaction is one of such ICI-related adverse events. In this report, we present the cases of three patients with stage IV melanoma who all developed mediastinal and hilar lymphadenopathy during ICI treatment. While a complete response was observed in one patient, near complete responses were observed in the other two patients. Amid these favorable outcomes, all patients developed mediastinal and hilar lymphadenopathy approximately 6 months after the initiation of immunotherapy. Biopsies were performed to explore the underlying pathology of the lymph nodes, which revealed granulomatous reactions rather than metastases. Hence, immunotherapy was continued in all patients. The development of granulomatous lymphadenitis associated with ICIs may mimic disease recurrence/progression clinically and radiographically. Awareness of such type of adverse event is crucial to decide whether to continue therapy or not.

18F FDG PET/CT and Novel Molecular Imaging for Directing Immunotherapy in Cancer

Immunotherapy has transformed the treatment landscape of many cancers, with durable responses in disease previously associated with a poor prognosis. Patient selection remains a challenge, with predictive biomarkers an urgent unmet clinical need. Current predictive biomarkers, including programmed death-ligand 1 (PD-L1) (measured with immunohistochemistry), are imperfect. Promising biomarkers, including tumor mutation burden and tumor infiltrating lymphocyte density, fail to consistently predict response and have yet to translate to routine clinical practice. Heterogeneity of immune response within and between lesions presents a further challenge where fluorine 18 fluorodeoxyglucose PET/CT has a potential role in assessing response, stratifying treatment, and detecting and monitoring immune-related toxicities. Novel radiopharmaceuticals also present a unique opportunity to define the immune tumor microenvironment to better predict which patients may respond to therapy, for example by means of in vivo whole-body PD-L1 and CD8+ T cell expression imaging. In addition, longitudinal molecular imaging may help further define dynamic changes, particularly in cases of immunotherapy resistance, helping to direct a more personalized therapeutic approach. This review highlights current and emerging applications of molecular imaging to stratify, predict, and monitor molecular dynamics and treatment response in areas of clinical need.

Suspected immune checkpoint inhibitor-induced pulmonary sarcoid reaction in metastatic renal cell carcinoma

We present the case of a 50-year-old male patient with metastatic clear cell renal cell carcinoma (mRCC) who developed a diffuse pulmonary opacification and lymphadenopathy during nivolumab maintenance therapy. This was diagnosed as presumed sarcoid granulomatous inflammatory reaction secondary to immunotherapy, which resolved with holding off therapy and the nivolumab was resumed.

A Decade of Success in Melanoma Immunotherapy and Targeted Therapy: What Every Radiologist Should Know

ABSTRACT

Treatment strategies for malignant melanoma have rapidly evolved over the past decade. Because of its propensity to develop advanced stage and metastatic disease, melanoma has contributed to the majority of mortalities among patients with skin cancer. The development of novel therapeutics such as immunotherapy and targeted molecular therapies has revolutionized the treatment of patients with advanced stage and metastatic malignant melanoma. Immune checkpoint inhibitors, BRAF/MEK inhibitors, and other revolutionary therapies have demonstrated remarkable success in the treatment of this common malignancy. Along with these advancements in systemic therapies, imaging has continued to play a critical role in the diagnosis and follow-up of patients with malignant melanoma. As the use of these novel therapies continues to expand, knowledge of the evolving therapeutic landscape of melanoma is becoming critical for radiologists. In this review, we provide a primer for radiologists outlining the evolution of immunotherapy and targeted therapy in the treatment of melanoma. We discuss the critical role of imaging in evaluation of treatment response, including a summary of current imaging response guidelines. Last, we summarize the essential role of imaging in the evaluation of potential adverse events seen in patients with malignant melanoma undergoing treatment with immune checkpoint inhibitors.

Sarcoid-like Granulomatosis Associated with Immune Checkpoint Inhibitors in Melanoma

We aimed to review the clinical and biological presentation of granulomatosis associated with immune-checkpoint inhibitors (ICI) in patients with melanoma and to explore its association with classical sarcoidosis as well as with cancer response to ICI. To this end, a retrospective study on 18 melanoma patients with histologically proven ICI-induced granulomatosis over a 12-year period in a single center, as well as on 67 similar cases reported in the literature, was conducted. Results indicate ICI-induced granulomatosis is an early side effect (median time to onset: 2 months). Its clinical presentation, with predominant (90%) thoracic involvement, histopathological appearance and supposed underlying biology (involving the mTOR pathway in immune cells, Th17 polarization and TReg dysfunction) are indistinguishable from those of sarcoidosis. Moreover, it appears to be associated with ICI benefit (>65% objective response rate). Evolution is generally favorable, and symptomatic steroid treatment and/or ICI discontinuation are rarely necessary. ICI-associated granulomatosis is critical to explore for several reasons. Practically, it is essential to differentiate it from cancer progression. Secondly, this “experimental” sarcoidosis brings new elements that may help to address sarcoidosis origin and pathophysiology. Its association with ICI efficacy must be confirmed on a larger scale but could have significant impacts on patient management and biomarker definition.

Case Report: New Onset Lymphadenopathy After Immune Checkpoint Inhibitor Therapy Presents a Clinicopathological and Radiological Challenge

The use of immune-checkpoint inhibitor (ICI) therapy has significantly improved patient outcomes in a wide variety of cancers and has become a cornerstone in the treatment of renal cell carcinoma. However, ICI treatment has the potential to cause a variety of immune-related adverse events (irAEs) that can affect any tissue or organ. This report describes the diagnostic dilemma of a patient with both RCC and diffuse large B-cell lymphoma who developed acute onset of fever and diffuse lymphadenopathy following treatment with combined ipilimumab and nivolumab. While diagnostic considerations included worsening lymphoma, hyperprogression of RCC, sarcoid-like reaction from immunotherapy, and fungal infection, his lymphadenopathy eventually resolved with treatment for histoplasmosis and discontinuation of immunotherapy. Despite only receiving two doses of immunotherapy, he has not required additional systemic therapy for RCC. This case demonstrates both the effectiveness of ICI therapy and the need for multidisciplinary approach to potential irAEs.

Role of Abdominal and Pelvic CT Scans in Diagnosis of Patients with Immunotherapy-Induced Colitis

Introduction:

Colitis is one of the most common immune-related adverse events in patients receiving immune checkpoint inhibitors. Although radiographic changes on computed tomography (CT), such as mild diffuse bowel thickening, mesenteric fat stranding, and mucosal enhancement, have been reported, the utility of CT in diagnosis of patients with suspected immune-related colitis is not well documented. The aim of this retrospective study was to determine the value of CT scans in diagnosis of immunotherapy-induced colitis.

Methods:

CT scans of the abdomen and pelvis of 34 patients receiving immunotherapy who had a clinical diagnosis of immunotherapy-induced colitis and 19 patients receiving immunotherapy without clinical symptoms of colitis (controls) were evaluated. Segments of the colon (rectum, sigmoid, descending, transverse, ascending, and cecum) were assessed independently by two abdominal imaging specialists, blinded to the clinical diagnosis. Each segment was assessed for radiographic signs such as mucosal enhancement, wall thickening, distension, and periserosal fat stranding. The presence of any of the signs was considered radiographic evidence of colitis.

Results:

CT findings suggestive of colitis was seen in 20 of 34 patients with symptoms of colitis and in 5 of 19 patients without symptoms of colitis. The sensitivity, specificity, positive predictive value, and negative predictive value for colitis on CT were 58.8%, 73.7%, 80%, and 50%, respectively.

Conclusions:

We found that CT had a low sensitivity, specificity, and negative predictive value for the diagnosis of immunotherapy-induced colitis. We therefore conclude that CT has a limited role in the diagnosis of patients with suspected uncomplicated immune-related colitis.

Checkpoint Inhibitor Pneumonitis Induced by Anti-PD-1/PD-L1 Therapy in Non-Small-Cell Lung Cancer: Occurrence and Mechanism

Immune checkpointty inhibitors (ICIs), particularly those targeting programmed death 1 (PD-1) and anti-programmed death ligand 1 (PD-L1), enhance the antitumor effect by restoring the function of the inhibited effector T cells and produce durable responses in a large variety of metastatic and late patients with non-small-cell lung cancer. Although often well tolerated, the activation of the immune system results in side effects known as immune-related adverse events (irAEs), which can affect multiple organ systems, including the lungs. The occurrence of severe pulmonary irAEs, especially checkpoint inhibitor pneumonitis (CIP), is rare but has extremely high mortality and often overlaps with the respiratory symptoms and imaging of primary tumors. The development of CIP may be accompanied by radiation pneumonia and infectious pneumonia, leading to the simultaneous occurrence of a mixture of several types of inflammation in the lungs. However, there is a lack of authoritative diagnosis, grading criteria and clarified mechanisms of CIP. In this article, we review the incidence and median time to onset of CIP in patients with non-small-cell lung cancer treated with PD-1/PD-L1 blockade in clinical studies. We also summarize the clinical features, potential mechanisms, management and predictive biomarkers of CIP caused by PD-1/PD-L1 blockade in non-small-cell lung cancer treatment.

Therapy-induced bone changes in oncology imaging with 18F-sodium fluoride (NaF) PET-CT

¹⁸F-Sodium fluoride (¹⁸F-NaF) is a PET tracer that is mostly used in the evaluation of bone metastasis in oncology cases. Recently, ¹⁸F-NaF PET/CT is gaining wide popularity owing to its higher sensitivity over the other conventional bone tracer with higher and rapid single-pass extraction, negligible plasma protein binding, rapid blood, and renal clearance. In the era of constant evolution of cancer therapy regimens, considerable bone health impact is seen in the form of avascular necrosis, insufficiency fractures, among others. A significant number of these therapy-induced changes show high bone turnover and thereby ¹⁸F-NaF accumulation, mimicking metastatic lesions. This article summarizes and illustrates the pattern and morphological features of ¹⁸F-NaF PET/CT findings in these changes in the context of clinical and therapeutic history.

Immune checkpoint inhibitors, endocrine adverse events, and outcomes of melanoma

OBJECTIVE

Immune checkpoint inhibitors (ICI) can cause endocrine adverse events. However, endocrine adverse events (AEs). However, endocrine AEs could be related to better treatment outcomes. Our aim was to investigate whether this holds true in a real-world setting of metastatic melanoma patients.

DESIGN

A retrospective single-institution study.

METHODS

We included 140 consecutive metastatic melanoma patients treated with ICI between January 2012 and May 2019. We assessed the endocrine toxicity and the best possible treatment outcomes from electronic patient records, including laboratory parameters and radiological images.

RESULTS

Of the treated patients, 21 patients (15%) were treated with ipilimumab, 46 (33%) with nivolumab, 67 (48%) with pembrolizumab, and 6 (4%) with combination therapy (ipilimumab + nivolumab). Endocrine AEs appeared in 29% (41/140) patients. Three patients had two different endocrine AEs. Thyroid disorders were the most common: 26% (36/140), followed by hypophysitis: 4% (5/140). Three subjects (2%, 3/140) were diagnosed with autoimmune diabetes. Three patients had to terminate treatment due to endocrine toxicity. Radiological manifestations of endocrine AEs were found in 16 patients (39%, 16/41). Endocrine toxicity was associated with significantly better treatment outcomes. Median progression-free survival (8.1 months, range 5.1-11.1 months vs 2.7 months, range 2.4-3.0 months, P < 0.001), and median overall survival (47.5 months, range 15.5-79.5 months vs 23.7 months, range 15.3-32.1 months, P = 0.035) were longer for patients experiencing endocrine AEs.

CONCLUSIONS

The higher number of endocrine AEs suggest that regular laboratory monitoring aids in AE detection. Endocrine AEs in metastatic melanoma may correlate with better treatment outcomes.

Pulmonary Toxicities of Immunotherapy

Immune checkpoint inhibitors are a form of immunotherapy that are increasingly being used in a wide variety of cancers. Immune-related adverse events (irAEs) pose a major challenge in the treatment of cancer patients. Pneumonitis, the most common lung irAE, can cause significant disruptions in the treatment of cancer and may be life-threatening. The goal of this chapter is to instruct readers on the incidence and clinical manifestations of pneumonitis and to offer guidance in the evaluation and treatment of patients with pneumonitis.

18F-FDG PET/CT Imaging of Immune Checkpoint Inhibitor-Related "Retroperitoneal Panniculitis"

ABSTRACT

A 71-year-old woman was operated on for undifferentiated lung adenocarcinoma. Four months after surgery, she developed bone and adrenal metastases. She underwent palliative radiation therapy of left scapula and right iliac bone. Thereafter, she started immune checkpoint inhibitor (ICI) therapy with anti-PD-1 antibodies achieving complete tumor response. Twenty months later, a follow-up 18F-FDG PET/CT confirmed tumor response and revealed high radiotracer accumulation in correspondence of retroperitoneal and subcutaneous fat opacities. The contiguous fasciae were mildly thickened. The temporal relation with ICI therapy together with tumor response and corticosteroids therapy effectiveness led to conclude for ICI-related adverse events.

Case report: Eosinophilic fasciitis induced by pembrolizumab with high FDG uptake on 18F-FDG-PET/CT

Eosinophilic fasciitis (EF) is a rare connective tissue disorder causing inflammation and fibrosing of fascia. In this study, we present a very rare case of an immune checkpoint inhibitor (ICI)-induced EF revealed by ¹⁸F-fluorodesoxyglucose positron emission tomography (FDG-PET/CT) 20 months after the initiation of Pembrolizumab treatment of a relapsed non-small cell lung cancer (NSCLC). This study presents a 52-year-old Caucasian woman clinically presenting asthenia, inflammatory muscle, and joint pain associated with subcutaneous nodules and symmetrical edema of the lower limbs. Iterative ¹⁸FDG-PET/CT scans allow us to guide the therapeutic strategy due to this atypical ICI adverse event.

Pearls and Pitfalls in the Imaging of Targeted Therapy and Immunotherapy in Lung Cancer

Most lung cancers are diagnosed at advanced stage when the cancer has metastasized outside the lung. These patients are not eligible for curative surgery or radiation therapy and treated with systemic therapy. Advances in the understanding of the biology of lung cancer has resulted in the development of targeted therapy aimed at specific genetic mutations identified with non-small cell lung cancer and immunotherapy that helps the immune system recognize tumors as foreign, stimulates the immune system, and removes the inhibition that allows growth and spread of cancer cells. Tumors treated with targeted or immunotherapies respond differently when compared with traditional chemotherapy and not captured by conventional response criteria such as the World Health Organization criteria and Response Evaluation Criteria in Solid Tumors. Therefore, several modified criteria have been developed to appropriately address the treatment response when using these novel agents. Numerous treatment-related side effects have been described that are important to recognize to avoid misinterpretation as worsening tumor and to ensure appropriate management.

Response criteria for immunotherapy and the radiologic patterns of immune-related adverse events

Immunotherapy has revolutionized clinical outcomes in both early-stage and advanced-stage malignancies. Immunotherapy has improved patient survival in both solid and hematologic disorders with the potential added benefit of less toxicity compared to conventional cytotoxic chemotherapy. Imaging plays a fundamental role in monitoring treatment response and assessment of immune-related adverse events, e.g. pneumonitis, colitis, etc. Familiarity with the current strategies of immune-related response evaluation and their limitations is essential for radiologists to guide clinicians with their treatment decisions. Radiologists should be aware of the wide spectrum of immune-related adverse events and their various radiological features as well as the patterns of treatment response associated with immunotherapies.

Treatment-induced sarcoidosis in a patient with metastatic clear cell ovarian cancer

Sarcoidosis is a granulomatous disease that commonly presents with lung or lymphatic system manifestations. Diagnosis is often delayed due to variable clinical presentation. This is a case of a patient with metastatic clear cell ovarian cancer who developed disease reoccurence after definitive treatment with surgery and adjuvant chemotherapy. She was treated with multiple lines of therapy, including investigational agents. During this time, she developed mediastinal lymphadenopathy and hypercalcaemia. Due to suspicion that her presentation was not a manifestation of her malignancy, she underwent two lymph node biopsies revealing granulomatous disease. She was initiated on prednisone for management of sarcoidosis, which led to radiologic, laboratory and symptomatic improvement. Although the precipitating factor for this patient's sarcoidosis cannot be definitively determined, nivolumab is a possible culprit. This case highlights the importance of a broad differential diagnosis when a patient undergoing antineoplastic treatment develops mediastinal lymphadenopathy or hypercalcaemia.

Development of thoracic sarcoid reactions associated with complete response to anti-PD-1 therapy in a patient with advanced cutaneous squamous cell carcinoma

In patients with advanced cutaneous squamous cell carcinoma (cSCC), positive efficacy data were reported for anti-PD-1 antibodies. However, anti-PD-1 treatment is associated with a wide range of immune-related adverse events (irAEs). Here, we report on a 78-year-old woman with a huge cSCC on the right cheek spanning from the temporal to the cervical region with evidence for infiltration of the parotid gland, right masseter muscle and right auditory canal. Ultrasound revealed cervical, submandibular and supraclavicular lymph node metastases on patient's right side. On the basis of a medical hardship application, treatment with pembrolizumab was initiated. After two applications, a dramatic regression of the tumour was observed. At this point, the patient was switched to cemiplimab, which, in the meantime, had become available in Germany. After 3 months on cemiplimab, the tumour-related ulcer on the right cheek showed almost complete regression and all previously affected lymph nodes displayed no evidence for malignancy. Thoracic computed tomography (CT) scans revealed enlarged mediastinal and bilateral hilar lymph nodes assessed as primarily reactive. Three months later, however, mediastinal and bilateral hilar lymph nodes further increased in size, accompanied by radiological alterations of the lung parenchyma. Lymph node biopsies revealed sarcoid reactions (SRs) including fibrotic non-caseating epitheloid cell granulomas surrounded by lymphocytes. Since the patient did not display any clinical symptoms, cemiplimab treatment was continued following a 4-week break. Three months later, CT showed significant regression of the described enlarged lymph nodes and parenchymal lung changes. Twenty months after anti-PD-1 treatment, the patient was still in complete remission. In conclusion, we describe, for the first time, the case of a patient with advanced cSCC who developed disseminated thoracic SRs which were associated with dramatic regression of tumour masses. Thus, as with other irAEs, development of SRs might be indicative of an anti-tumour response to anti-PD-1 therapy.

Rheumatic Manifestations and Diseases From Immune Checkpoint Inhibitors in Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs), which can enhance antitumor immunity and inhibit cancer growth, have revolutionized the treatment of multiple cancers and dramatically decreased mortality. However, treatment with ICIs is directly associated with immune-related adverse events (irAEs) because of inflammation in off-target organs and autoimmunity resulting from non-specific immune activation. These irAEs can cause rheumatic diseases and manifestations such as inflammatory arthritis, polymyalgia rheumatica, myositis, vasculitis, Sicca and Sjogen's syndrome, and systemic lupus erythematosus. Early diagnosis and treatment of these adverse events will improve outcomes and quality of life for cancer patients. The treatment of rheumatic diseases induced by ICIs requires multidisciplinary cooperation among physicians. Furthermore, the underlying mechanisms are not fully understood and it is difficult to predict and evaluate these side effects precisely. In this review, we summarize available studies and findings about rheumatic irAEs, focusing mainly on the clinical manifestations, epidemiology, possible mechanisms, and guiding principles for treating these irAEs.

Imaging evaluation of lung cancer treated with PD-1/PD-L1 inhibitors

Immunotherapy (PD-1/PD-L1 inhibitors) has attracted attention for lung cancer treatment and recasted the administration of immunotherapeutics to patients who have advanced/metastatic diseases. Whether in combination or as monotherapy, these medications have become common therapies for certain patients with lung cancer. Moreover, their usage is expected to expand widely in the future. This review aims to discuss the imaging evaluation of lung cancer response to PD-1/PD-L1 therapy with focus on new radiological criteria for immunotherapy response. Abnormal radiological responses (pseudoprogression, dissociative responses, and hyperprogression) and immune-related adverse events are also described.

Assessment of early metabolic progression in melanoma patients under immunotherapy: an 18F-FDG PET/CT study

BACKGROUND

The usage of immune checkpoint inhibitors (ICIs) is the standard practice for the treatment of metastatic melanoma. However, a significant amount of patients show no response to immunotherapy, while issues on its reliable response interpretation exist. Aim of this study was to investigate the phenomenon of early disease progression in 2-deoxy-2-(18F)fluoro-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in melanoma patients treated with ICIs.

METHODS

Thirty-one patients under ICIs serially monitored with 18F-FDG PET/CT were enrolled. All patients exhibited progressive metabolic disease (PMD) after two ICIs' cycles according to the European Organization for Research and Treatment of Cancer (EORTC) criteria, and were characterized as unconfirmed PMD (uPMD). They were further followed with at least one PET/CT for either confirmation of PMD (cPMD) or demonstration of pseudoprogression remission. Patients were also evaluated with the PET Response Evaluation Criteria for Immunotherapy (PERCIMT). Moreover, in an attempt to investigate immune activation, the spleen to liver ratios (SLRmean, SLRmax) of 18F-FDG uptake were measured.

RESULTS

Median follow up was 69.7 months [64.6-NA]. According to EORTC, 26/31 patients with uPMD eventually showed cPMD (83.9%) and 5/31 patients showed pseudoprogression (16.1%). Patients with cPMD (n = 26) had a median OS of 10.9 months [8.5-NA], while those with pseudoprogression (n = 5) did not reach a median OS [40.9-NA]. Respectively, after application of PERCIMT, 2/5 patients of the pseudoprogression group were correctly classified as non-PMD, reducing the uPMD cohort to 29 patients; eventually, 26/29 patients demonstrated cPMD (89.7%) and 3/29 pseudoprogression (10.3%). One further patient with pseudoprogression exhibited transient, sarcoid-like, mediastinal/hilar lymphadenopathy, a known immune-related adverse event (irAE). Finally, patients eventually showing cPMD exhibited a significantly higher SLRmean than those showing pseudoprogression after two ICIs' cycles (p = 0.038).

CONCLUSION

PET/CT, performed already after administration of two ICIs' cycles, can identify the majority of non-responders in melanoma immunotherapy. In order to tackle however, the non-negligible phenomenon of pseudoprogression, another follow-up PET/CT, the usage of novel response criteria and vigilance over emergence of radiological irAEs are recommended. Moreover, the investigation of spleen glucose metabolism may offer further prognostic information in melanoma patients under ICIs.

Immune checkpoint inhibitor-associated sarcoidosis: A usually benign disease that does not require immunotherapy discontinuation

OBJECTIVE

To analyse the clinical patterns of sarcoidosis triggered by immune checkpoint inhibitors (ICIs) in patients with cancer.

PATIENTS AND METHODS

The ImmunoCancer International Registry is a big data-sharing multidisciplinary network from 18 countries dedicated to evaluating the clinical research of immune-related adverse events related to cancer immunotherapies.

RESULTS

We identified 32 patients with biopsy-proven sarcoidosis. Underlying cancer included mainly melanoma (n = 24). Cancer immunotherapy consisted of monotherapy in 19 cases (anti-PD-1 in 18 and ipilimumab in 1) or combined ipilimumab + nivolumab in 13. The time median interval between initiation of ICI and sarcoidosis diagnosis was 3 months (range, 2-29 months). The use of combined ICI was associated with a shorter delay in developing sarcoidosis symptoms. The disease was symptomatic in 19 (59%) cases with mostly cutaneous, respiratory and general symptoms. The organs involved included mainly the mediastinal lymph nodes (n = 32), the lungs (n = 11), the skin (n = 10) and the eyes (n = 5). Pulmonary computed tomography studies showed bilateral hilar lymphadenopathy in all cases. There was no severe manifestation. Specific systemic therapy was required in only 12 patients (37%): oral glucocorticoids in 9, and hydroxychloroquine in 3. ICIs were held in 25 patients (78%) and definitively discontinued in 18 (56%) patients. Seven patients continued ICI treatment with a second flare in one case. In six additional patients, an ICI was reintroduced with no harm, and sarcoidosis relapsed in one of them.

CONCLUSION

Our study shows that ICI-related sarcoidosis seems to have a specific profile, possibly more benign than that of idiopathic sarcoidosis, and does not necessarily imply ICI discontinuation.

Immune checkpoint inhibitor related adverse effects and FDG PET/CT findings

Immune check-point inhibitor (ICI) treatments activate the T-cells against tumor. Activated T-cells not only attack the tumor but also healthy cells, causing an autoimmune reaction in various tissues. These immune related adverse effects (IRAE) cause ¹⁸F-fluorodeoxyglucose (FDG) uptake in various tissues due to inflammation. It is important to recognize and report these findings on FDG Positron Emission Tomography/Computed Tomography (PET/CT) studies. FDG PET helps to determine the presence, location and severity of IRAEs. In severe cases, ICI treatments are interrupted or suspended and anti-inflammatory treatments are started. FDG uptake due IRAEs may mimic metastases or disease progression. Their presence may also help predicting response to treatment and have prognostic implications. In this review article, we will provide basic information about ICI treatments, IRAEs and FDG PET/CT findings.

Practical Considerations When Interpreting FDG PET/CT Imaging for Staging and Treatment Response Assessment in Melanoma Patients

While FDG PET/CT bears a high sensitivity and specificity for the staging of stage III and IV melanoma as well as for the purpose of melanoma recurrence detection, overall results tend to vary from one part of the body to another as well as for melanoma from cutaneous or choroidal origin. In this paper, organ or site-related differences in sensitivity and specificity in melanoma patients, both from cutaneous and choroidal origin, as well as their impact on clinical decision making are discussed. Furthermore, with the advent of immunotherapy for the treatment of malignant melanoma, post-treatment related potential false positive findings have emerged, the knowledge of which is essential for accurate treatment response assessment. These post-treatment related potential false positive findings are summarized in this paper so as to help the nuclear medicine physician in avoiding erroneous interpretation of acquired FDG PET/CT images in melanoma patients receiving immuntherapy.

Rheumatic Immune-Related Adverse Events-A Consequence of Immune Checkpoint Inhibitor Therapy

Simple Summary

Cancer therapy has evolved over the years, immunotherapy being the most used for untreatable malignant tumors. Immune checkpoint inhibitors decrease the ability of tumor cells to escape the immune system. Although immune checkpoint inhibitors have a significant impact in the treatment of cancer, they are associated with various adverse effects, mostly inflammation. The adverse events related to the immune system may affect basically every tissue in the human body, including the digestive tract, endocrine glands, liver, skin, cardiovascular, pulmonary and, also, rheumatic systems. In this review, we address the rheumatic immune-related adverse events related to immunotherapy by depicting the characteristics, diagnostic approach and treatment options.

Abstract

The advent of immunotherapy has changed the management and therapeutic methods for a variety of malignant tumors in the last decade. Unlike traditional cytotoxic chemotherapy, which works by interfering with cancer cell growth via various pathways and stages of the cell cycle, cancer immunotherapy uses the immune system to reduce malignant cells’ ability to escape the immune system and combat cell proliferation. The widespread use of immune checkpoint inhibitors (ICIs) over the past 10 years has presented valuable information on the profiles of toxic adverse effects. The attenuation of T-lymphocyte inhibitory mechanisms by ICIs results in immune system hyperactivation, which, as expected, is associated with various adverse events defined by inflammation. These adverse events, known as immune-related adverse events (ir-AEs), may affect any type of tissue throughout the human body, which includes the digestive tract, endocrine glands, liver and skin, with reports of cardiovascular, pulmonary and rheumatic ir-AEs as well. The adverse events that arise from ICI therapy are both novel and unique compared to those of the conventional treatment options. Thus, they require a multidisciplinary approach and continuous updates on the diagnostic approach and management.

Post-immunotherapy imaging in lung cancer

By boosting the immune system, immunotherapy with immune checkpoint inhibitors (ICIs) has altered the management of patients with various cancers including those with metastatic non-small cell lung cancer (NSCLC). As a result of immune system activation, ICIs are associated with unique response patterns (that are not addressed by traditional response criteria) and inflammatory side effects termed immune-related adverse events. In this article, we will review the role of immunotherapy in cancer treatment, specifically ICIs used in NSCLC treatment, radiological response criteria of immunotherapy, and the imaging spectrum of immune-related adverse events.

The knowns & unknowns of pulmonary toxicity following immune checkpoint inhibitor therapies: a narrative review

Since their discovery immune checkpoint inhibitors (ICI) have dramatically changed the treatment landscape for many cancers. In addition to their efficacy they are generally well tolerated, however, they have led to a new range of immune-related adverse events (irAEs) including pneumonitis. While not the most frequently reported immune-related adverse event in the clinical trial setting, recent real-world data suggests a significantly higher rate of pneumonitis leading to treatment suspension or cessation. It also appears to disproportionately contribute to immune-related mortality, particularly with anti-PD-1/PD-L1 treatment. While indicators have emerged regarding risk factors, incomplete prospective recording of patient characteristics hampers strong conclusions. Presenting symptoms are non-specific and the differential diagnosis is broad, made more complex by concomitant treatment with traditional chemotherapy or radiotherapy. Radiological findings are diverse and inconsistent terminology makes comparison and more complete characterization difficult. Further, little is known about the role of baseline testing or surveillance for early detection of pneumonitis, or the real-world role of bronchoscopy or biopsy in assessment. Scant literature exists to direct these complex decisions, so treatment guidelines have been published based on expert consensus. Here we provide a narrative review of what is known about ICI pneumonitis and propose key questions to enhance our understanding into the future.

Interim [18F]FDG PET/CT can predict response to anti-PD-1 treatment in metastatic melanoma

PURPOSE

In an attempt to identify biomarkers that can reliably predict long-term outcomes to immunotherapy in metastatic melanoma, we investigated the prognostic role of [18F]FDG PET/CT, performed at baseline and early during the course of anti-PD-1 treatment.

METHODS

Twenty-five patients with stage IV melanoma, scheduled for treatment with PD-1 inhibitors, were enrolled in the study (pembrolizumab, n = 8 patients; nivolumab, n = 4 patients; nivolumab/ipilimumab, 13 patients). [18F]FDG PET/CT was performed before the start of treatment (baseline PET/CT) and after the initial two cycles of PD-1 blockade administration (interim PET/CT). Seventeen patients underwent also a third PET/CT scan after administration of four cycles of treatment. Evaluation of patients' response by means of PET/CT was performed after application of the European Organization for Research and Treatment of Cancer (EORTC) 1999 criteria and the PET Response Evaluation Criteria for IMmunoTherapy (PERCIMT). Response to treatment was classified into 4 categories: complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD). Patients were further grouped into two groups: those demonstrating metabolic benefit (MB), including patients with SMD, PMR, and CMR, and those demonstrating no MB (no-MB), including patients with PMD. Moreover, patterns of [18F]FDG uptake suggestive of radiologic immune-related adverse events (irAEs) were documented. Progression-free survival (PFS) was measured from the date of interim PET/CT until disease progression or death from any cause.

RESULTS

Median follow-up from interim PET/CT was 24.2 months (19.3-41.7 months). According to the EORTC criteria, 14 patients showed MB (1 CMR, 6 PMR, and 7 SMD), while 11 patients showed no-MB (PMD). Respectively, the application of the PERCIMT criteria revealed that 19 patients had MB (1 CMR, 6 PMR, and 12 SMD), and 6 of them had no-MB (PMD). With regard to PFS, no significant difference was observed between patients with MB and no-MB on interim PET/CT according to the EORTC criteria (p = 0.088). In contrary, according to the PERCIMT criteria, patients demonstrating MB had a significantly longer PFS than those showing no-MB (p = 0.045). The emergence of radiologic irAEs (n = 11 patients) was not associated with a significant survival benefit. Regarding the sub-cohort undergoing also a third PET/CT, 14/17 patients (82%) showed concordant responses and 3/17 (18%) had a mismatch of response assessment between interim and late PET/CT.

CONCLUSION

PET/CT-based response of metastatic melanoma to PD-1 blockade after application of the recently proposed PERCIMT criteria is significantly correlated with PFS. This highlights the potential ability of [18F]FDG PET/CT for early stratification of response to anti-PD-1 agents, a finding with possible significant clinical and financial implications. Further studies including larger numbers of patients are necessary to validate these results.

Sarcoid-like reaction in a BRAF V600E-mutated metastatic melanoma patient during treatment with BRAF/MEK-targeted therapy

Treatment with combined BRAF and MEK inhibition is widely accepted as a first-line treatment option for patients with advanced BRAF V600E mutant melanoma. It is generally well-tolerated and has limited side-effects. However, we report a case of a sarcoid-like syndrome induced by treatment with dabrafenib/trametinib (D/T) in a patient with stage IV-M1d melanoma. Sarcoid-like syndrome is a known side-effect of immune checkpoint-inhibition therapy but has only rarely been described in BRAF/MEK inhibition. However, recognizing this side-effect is important because of potential misinterpretation as progressive disease and influence on treatment. We describe a 48-year-old female patient who initially presented with solitary brain metastasis and diffuse lung lesions. She was treated with D/T to which she had an initial response in all lesions. One year later, new hilar and mediastinal lymphadenopathies were detected. Imaging was suggestive of the sarcoid-like syndrome. An endoscopic biopsy of the enlarged lymph node showed no melanoma cells. Treatment was continued. Three months later, the patient experienced a drop in hemoglobin, which prompted further investigations into possible occult intestinal metastasis. Video capsule examination revealed a metastatic lesion in the small intestine. A treatment switch to the combination of checkpoint inhibitors nivolumab and ipilimumab successfully treated both lung and small intestine lesions. After the third dose of this combination therapy, she developed an immune-related pneumonitis. Treatment with corticosteroids resolved the pneumonitis and decreased metabolism in the sarcoid-like syndrome. The treatment was not restarted afterward. She remains free of the disease up to today, 2.5 years after diagnosis.

CT, MRI and PET/CT features of abdominal manifestations of cutaneous melanoma: a review of current concepts in the era of tumor-specific therapies

Abdominal manifestations in patients with cutaneous melanoma include involvement due to metastatic spread and immune checkpoint inhibitor induced adverse events. The purpose of this review is to provide a critical overview of abdominal manifestations in patients with cutaneous melanoma and highlight the current imaging challenges in the era of tumor-specific therapies. Immune checkpoint inhibitors represent a treatment with demonstrated efficacy in the treatment of advanced cutaneous melanoma but are associated with several abdominal adverse events that must be recognized. CT has a role in the identification of colitis, enteritis and pancreatitis, whereas MRI has an important role in the diagnosis of autoimmune pancreatitis. Current evidence demonstrates that MRI should be the preferred imaging technique for the detection and characterization of hepatic and splenic metastases from cutaneous melanoma. The role of ¹⁸F-FDG-PET/CT should be further evaluated but current literature suggests an efficacy in the detection of pancreatic metastases not seen on CT and MRI.

Case 286: Sarcoidlike Granulomatosis and Lymphadenopathy-Thoracic Manifestations of Nivolumab Drug Toxicity

History A 70-year-old man had a posterior left thigh lesion confirmed to be biopsy-proven melanoma. The patient underwent wide excision and sentinel node biopsy, which showed absence of residual melanoma. Two years later, the patient noticed a subcentimeter subcutaneous lump in his thigh. Repeat excisional biopsy showed involvement of the surrounding soft tissue, consistent with a satellite lesion. Follow-up combined PET/CT revealed satellite nodules around the primary lesion, enabling confirmation of subcutaneous metastatic disease. The patient was subsequently started on nivolumab, an anti-programmed cell death 1 (PD-1) immune checkpoint inhibitor that blocks PD-1 and is approved as a first-line treatment in patients with advanced metastatic melanoma. On the baseline scan prior to starting nivolumab, there were no CT findings that suggested metastatic disease, nor were there enlarged mediastinal or hilar lymph nodes. Five months after initiation of nivolumab treatment, the first follow-up chest CT scan was performed and showed new findings in the mediastinum and bilateral lungs. The patient remained asymptomatic during the treatment period. Furthermore, the subcutaneous metastatic disease remained stable during the treatment period, and no other site of metastatic disease was noted on follow-up CT scans obtained during the first 5 months of treatment. The patient had no prior history of infectious or occupational exposures. During the nivolumab treatment cycle, his pertinent laboratory values and physical examination findings were unremarkable.