Clinicopathological characteristics and management of colitis with anti-PD1 immunotherapy alone or in combination with ipilimumab

Focus on Immune Checkpoint Inhibitors-related Intestinal Inflammation: From Pathogenesis to Therapeutical Approach

Recently, antitumor immunotherapies have witnessed a breakthrough with the emergence of immune checkpoint inhibitors (ICIs) including programmed cell death-1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors. Unfortunately, the use of ICIs has also led to the advent of a novel class of adverse events that differ from those of classic chemotherapeutics and are more reminiscent of autoimmune diseases, the immune-related adverse events (IRAEs). Herein, we performed an insight of the main IRAEs associated with ICIs, focusing on gastroenterological IRAEs and specifically on checkpoint inhibitor colitis, which represents the most widely reported IRAE to date. We comprehensively dissected the current evidence regarding pathogenesis, diagnosis, and management of ICIs-induced colitis, touching upon also on innovative therapies.

Review article: Contemporary management of gastrointestinal, pancreatic and hepatic toxicities of immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) are effective oncologic agents which frequently cause immune-related adverse events (irAEs) which can impact multiple organ systems. Onco-Gastroenterology is a novel and emerging subspecialty within gastroenterology focused on cancer treatment-related complications. Gastroenterologists must be prepared to identify and manage diverse immune-mediated toxicities including enterocolitis, hepatitis, pancreatitis and other ICI-induced toxicities.

AIM

To provide a narrative review of the epidemiology, diagnostic evaluation and management of checkpoint inhibitor-induced gastrointestinal and hepatic toxicities.

METHODS

We searched Cochrane and PubMed databases for articles published through August 2023.

RESULTS

Gastrointestinal and hepatic irAEs include most commonly enterocolitis and hepatitis, but also pancreatitis, oesophagitis, gastritis, motility disorders (gastroparesis) and other rarer toxicities. Guidelines from the National Comprehensive Cancer Network, American Society of Clinical Oncology and European Society for Medical Oncology, in combination with emerging cohort and clinical trial data, offer strategies for management of ICI toxicities. Evaluation of irAEs severity by formal classification and clinical stability, and a thorough workup for alternative etiologies which may clinically mimic irAEs underlie initial management. Treatments include corticosteroids, biologics and other immunosuppressive agents plus supportive care; decisions on dosing, timing and choice of steroid adjuncts and potential for subsequent checkpoint inhibitor dosing are nuanced and toxicity-specific.

CONCLUSIONS

Expanding clinical trial and cohort data have clarified the epidemiology and clinical characteristics of gastrointestinal, pancreatic and hepatic toxicities of ICIs. Guidelines, though valuable, remain based principally on retrospective cohort data. Quality prospective, controlled studies may refine algorithms for treatment and potential immunotherapy rechallenge.

Management of liver and gastrointestinal toxicity induced by immune checkpoint inhibitors: Position statement of the AEEH-AEG-SEPD-SEOM-GETECCU

The development of the immune checkpoint inhibitors (ICI) is one of the most remarkable achievements in cancer therapy in recent years. However, their exponential use has led to an increase in immune-related adverse events (irAEs). Gastrointestinal and liver events encompass hepatitis, colitis and upper digestive tract symptoms accounting for the most common irAEs, with incidence rates varying from 2% to 40%, the latter in patients undergoing combined ICIs therapy. Based on the current scientific evidence derived from both randomized clinical trials and real-world studies, this statement document provides recommendations on the diagnosis, treatment and prognosis of the gastrointestinal and hepatic ICI-induced adverse events.

Polygenic risk score for ulcerative colitis predicts immune checkpoint inhibitor-mediated colitis

Immune checkpoint inhibitor-mediated colitis (IMC) is a common adverse event of treatment with immune checkpoint inhibitors (ICI). We hypothesize that genetic susceptibility to Crohn's disease (CD) and ulcerative colitis (UC) predisposes to IMC. In this study, we first develop a polygenic risk scores for CD (PRSCD) and UC (PRSUC) in cancer-free individuals and then test these PRSs on IMC in a cohort of 1316 patients with ICI-treated non-small cell lung cancer and perform a replication in 873 ICI-treated pan-cancer patients. In a meta-analysis, the PRSUC predicts all-grade IMC (ORmeta=1.35 per standard deviation [SD], 95% CI = 1.12-1.64, P = 2×10-03) and severe IMC (ORmeta=1.49 per SD, 95% CI = 1.18-1.88, P = 9×10-04). PRSCD is not associated with IMC. Furthermore, PRSUC predicts severe IMC among patients treated with combination ICIs (ORmeta=2.20 per SD, 95% CI = 1.07-4.53, P = 0.03). Overall, PRSUC can identify patients receiving ICI at risk of developing IMC and may be useful to monitor patients and improve patient outcomes.

The side effect registry immuno-oncology (SERIO) - A tool for systematic analysis of immunotherapy-induced side effects

BACKGROUND

Immunotherapies such as immune checkpoint inhibitors (ICI) are effective in multiple tumor entities but induce a plethora of side effects. Comprehensive real-world analyses are essential to identify new signals, characterize diagnostic features, enable risk assessment, determine pathomechanisms, assess effectiveness of side effect management and compare tumor outcomes.

METHODS

The international online `Side-Effect Registry Immuno-Oncology´ (SERIO; www.serio-registry.org) collects rare, complex, and severe immunotherapy-induced side effects across all tumor entities with a strong focus on ICI-induced immune-related adverse events (irAE). The relational database management system (RDMS) contains structured data on patient and tumor characteristics, type of immunotherapy, treatment of side effects, and outcome of tumor and irAE. Data are captured within 25 organ modules including new modules for immune effector cell-associated neurotoxicity syndrome (ICANS) for CAR-T-cell therapies and cytokine release syndrome (CRS) for bispecific antibodies. Information on biological samples is gathered.

RESULTS

A total of 1398 irAE cases have been documented by 58 centers from 13 countries in patients with 17 tumor types. IrAEs were induced by nine different immunotherapies including tebentafusp and CAR-T cell therapies, and resulted, among others, in neurological (7.6%), pulmonary (4.0%), and cardiac toxicities (2.9%). 50.0% of all irAEs were graded severe or life-threatening and 23.0% of patients received second-line therapy for steroid-refractory or steroid-dependent irAE. SERIO has contributed to 44 original publications on topics ranging from irMyocarditis to irEncephalitis to long-term persistent sequelae of immunotherapy.

CONCLUSIONS

A reliable evidence base is crucial for decision-making in rare, complex or therapy-refractory irAE. SERIO can help optimize side effect management and thereby reduce morbidity and mortality induced by immunotherapy.

Management of liver and gastrointestinal toxicity induced by immune checkpoint inhibitors: Position statement of the AEEH-AEG-SEPD-SEOM-GETECCU

The development of the immune checkpoint inhibitors (ICI) is one of the most remarkable achievements in cancer therapy in recent years. However, their exponential use has led to an increase in immune-related adverse events (irAEs). Gastrointestinal and liver events encompass hepatitis, colitis and upper digestive tract symptoms accounting for the most common irAEs, with incidence rates varying from 2 % to 40 %, the latter in patients undergoing combined ICIs therapy. Based on the current scientific evidence derived from both randomized clinical trials and real-world studies, this statement document provides recommendations on the diagnosis, treatment and prognosis of the gastrointestinal and hepatic ICI-induced adverse events.

Management of infliximab refractory immune checkpoint inhibitor gastrointestinal toxicity: a multicenter case series

BACKGROUND

Immune checkpoint inhibitor (ICI) gastrointestinal toxicity (gastritis, enteritis, colitis) is a major cause of morbidity and treatment-related death. Guidelines agree steroid-refractory cases warrant infliximab, however best management of infliximab-refractory ICI gastrointestinal toxicity (IRIGItox) is unknown.

METHODS

We conducted an international multicenter retrospective case series. IRIGItox was defined as failure of symptom resolution ≤grade 1 (Common Terminology Criteria for Adverse Events V.5.0) following ≥2 infliximab doses or failure of symptom resolution ≤grade 2 after one dose. Data were extracted regarding demographics, steroid use, response to treatment, and survival outcomes. Toxicity was graded at symptom onset and time of infliximab failure. Efficacy of infliximab refractory therapy was assessed by symptom resolution, time to resolution and steroid wean duration. Survival outcomes were examined based on immunosuppressive therapy received.

RESULTS

78 patients were identified: median age 60 years; 56% men; majority melanoma (N=70, 90%); 60 (77%) received anti-cytotoxic T-lymphocyte-associated protein 4 alone or in combination with anti-programmed cell death protein-1 and most had colitis (N=74, 95%). 106 post-infliximab treatments were given: 31 calcineurin inhibitors (CNIs); 27 antimetabolites (mycophenolate, azathioprine); 16 non-systemic immunomodulatory agents (eg, mesalazine or budesonide); 15 vedolizumab; 5 other biologics (anti-interleukin-12/23, 16, Janus kinase inhibitors) and 7 interventional procedures (including colectomy); 5 did not receive post-infliximab therapy. Symptom resolution was achieved in most (N=23/31, 74%) patients treated with CNIs; 12/27 (44%) with antimetabolites; 7/16 (44%) with non-systemic immunomodulation, 8/15 (53%) with vedolizumab and 5/7 (71%) with interventional procedures. No non-vedolizumab biologics resulted in toxicity resolution. CNIs had the shortest time to symptom resolution (12 days) and steroid wean (43 days); however, were associated with poorer event-free survival (6.3 months) and overall survival (26.8 months) than other agents. Conversely, vedolizumab had the longest time to toxicity resolution and steroid wean, 66 and 124 days, but most favorable survival data: EFS 24.5 months; median OS not reached. Six death occurred (three due to IRIGItox or management of toxicity; three with persisting IRIGItox and progressive disease).

CONCLUSIONS

IRIGItox causes major morbidity and mortality. Management is heterogeneous. CNIs appear most likely to result in toxicity resolution in the shortest time period, however, are associated with poorer oncological outcomes in contrast to vedolizumab.

Enterocolitis and other immunotherapy and targeted therapy-related gastrointestinal manifestations: A review for gastroenterologist

New oncologic treatments, particularly immunotherapy (IT), have revolutionized the treatment of advanced-stage malignant tumors. Immune checkpoint inhibitors are the main form of IT and act by increasing T cell activity and the organism's immune response against neoplastic cells. Targeted therapy is another form of IT that acts by inhibiting oncogenes or inflammation signaling and tumor angiogenesis pathways. However, these mechanisms of tumor destruction can interfere with the host's immune self-tolerance or with the mechanisms of epithelial tissue repair and predispose to immune system-mediated adverse events that can affect multiple organs, including the digestive tract. The gastrointestinal manifestations of damage caused by IT can range from low-grade mucositis to ulceration, and in some cases, necrosis and perforation. Any part of the gastrointestinal tract can be affected, but there is greater involvement of the small bowel and colon, with a pattern similar to that seen in inflammatory bowel disease. The most common clinical manifestation is chronic diarrhea. The differential diagnosis includes enteropathogenic infections, especially those caused by opportunistic microorganisms; adverse drug reactions; and other inflammatory and malabsorption disorders. Treatment is guided by damage severity. Mild cases can be treated with antidiarrheals and rehydration in the outpatient setting; moderate cases with hospitalization, systemic steroids, and temporary suspension of IT; and severe cases with immunosuppressants or biologic agents and definitive suspension of IT.

Treatment and outcomes of immune checkpoint inhibitors-associated colitis/diarrhea: A systematic review and meta-analysis

BACKGROUND

Immune checkpoint inhibitors (ICIs) have improved the outcomes of cancer patients. However, ICIs often lead to colitis/diarrhea. This study aimed to assess the treatment of ICIs-associated colitis/diarrhea and outcomes.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched for eligible studies which investigated the treatment and outcomes of colitis/diarrhea developing in patients who received ICIs. The pooled incidences of any-grade colitis/diarrhea, low-grade colitis, high-grade colitis, low-grade diarrhea, and high-grade diarrhea as well as the pooled rates of response to treatment, mortality, and ICIs permanent discontinuation and restarts in patients with ICIs-associated colitis/diarrhea were estimated using a random-effects model.

RESULTS

Among the 11,492 papers initially identified, 27 studies were included. The pooled incidences of any-grade colitis/diarrhea, low-grade colitis, high-grade colitis, low-grade diarrhea, and high-grade diarrhea were 17%, 3%, 17%, 13%, and 15%, respectively. The pooled rates of overall response, response to corticosteroid therapy, and response to biological agents were 88%, 50%, and 96%, respectively. The pooled short-term mortality in patients with ICIs-associated colitis/diarrhea was 2%. The pooled incidences of ICIs permanent discontinuation and restarts were 43% and 33%, respectively.

CONCLUSION

ICIs-associated colitis/diarrhea is common, but rarely lethal. Half of them are responsive to corticosteroid therapy. There is a fairly high rate of response to biological agents in steroid-refractory colitis/diarrhea patients.

Polygenic risk score for ulcerative colitis predicts immune checkpoint inhibitor-mediated colitis

Immune checkpoint inhibitors (ICIs) are a remarkable advancement in cancer therapeutics; however, a substantial proportion of patients develop severe immune-related adverse events (irAEs). Understanding and predicting irAEs is a key to advancing precision immuno-oncology. Immune checkpoint inhibitor-mediated colitis (IMC) is a significant complication from ICI and can have life-threatening consequences. Based on clinical presentation, IMC mimics inflammatory bowel disease, however the link is poorly understood. We hypothesized that genetic susceptibility to Crohn's disease (CD) and ulcerative colitis (UC) may predispose to IMC. We developed and validated polygenic risk scores for CD (PRSCD) and UC (PRSUC) in cancer-free individuals and assessed the role of each of these PRSs on IMC in a cohort of 1,316 patients with non-small cell lung cancer who received ICIs. Prevalence of all-grade IMC in our cohort was 4% (55 cases), and for severe IMC, 2.5% (32 cases). The PRSUC predicted the development of all-grade IMC (HR=1.34 per standard deviation [SD], 95% CI=1.02-1.76, P=0.04) and severe IMC (HR=1.62 per SD, 95% CI=1.12-2.35, P=0.01). PRSCD was not associated with IMC or severe IMC. The association between PRSUC and IMC (all-grade and severe) was consistent in an independent pan-cancer cohort of patients treated with ICIs. Furthermore, PRSUC predicted severe IMC among patients treated with combination ICIs (OR = 2.20 per SD, 95% CI = 1.07-4.53, P=0.03). This is the first study to demonstrate the potential clinical utility of a PRS for ulcerative colitis in identifying patients receiving ICI at high risk of developing IMC, where risk reduction and close monitoring strategies could help improve overall patient outcomes.

Immunosuppression for immune-related adverse events during checkpoint inhibition: an intricate balance

Immune checkpoint inhibitors (ICIs) have changed perspectives for patients with cancer, but come with severe immune-related adverse events (irAEs). To prevent fatality or chronicity, these irAEs are often promptly treated with high-dose immunosuppressants. Until recently, evidence on the effects of irAE management on ICI efficacy has been sparse. As a result, algorithms for irAE management are mostly expert-opinion based and barely consider possible detrimental effects of immunosuppressants on ICI efficacy. However, recent growing evidence suggests that vigorous immunosuppressive management of irAEs comes with unfavourable effects on ICI efficacy and survival. With expansion of the indications of ICIs, evidence-based treatment of irAEs without hampering tumour control becomes more and more important. In this review, we discuss novel evidence from pre-clinical and clinical studies on the effects of different irAE management regimens including corticosteroids, TNF inhibition and tocilizumab on cancer control and survival. We provide recommendations for pre-clinical research, cohort studies and clinical trials that can help clinicians in tailored irAE management, minimising patients' burden while maintaining ICI efficacy.

Discovery of Targets for Immune-Metabolic Antitumor Drugs Identifies Estrogen-Related Receptor Alpha

Drugs that kill tumors through multiple mechanisms have the potential for broad clinical benefits. Here, we first developed an in silico multiomics approach (BipotentR) to find cancer cell-specific regulators that simultaneously modulate tumor immunity and another oncogenic pathway and then used it to identify 38 candidate immune-metabolic regulators. We show the tumor activities of these regulators stratify patients with melanoma by their response to anti-PD-1 using machine learning and deep neural approaches, which improve the predictive power of current biomarkers. The topmost identified regulator, ESRRA, is activated in immunotherapy-resistant tumors. Its inhibition killed tumors by suppressing energy metabolism and activating two immune mechanisms: (i) cytokine induction, causing proinflammatory macrophage polarization, and (ii) antigen-presentation stimulation, recruiting CD8+ T cells into tumors. We also demonstrate a wide utility of BipotentR by applying it to angiogenesis and growth suppressor evasion pathways. BipotentR (http://bipotentr.dfci.harvard.edu/) provides a resource for evaluating patient response and discovering drug targets that act simultaneously through multiple mechanisms.

SIGNIFICANCE

BipotentR presents resources for evaluating patient response and identifying targets for drugs that can kill tumors through multiple mechanisms concurrently. Inhibition of the topmost candidate target killed tumors by suppressing energy metabolism and effects on two immune mechanisms. This article is highlighted in the In This Issue feature, p. 517.

Distinct pretreatment innate immune landscape and posttreatment T cell responses underlie immunotherapy-induced colitis

Immune-related adverse events represent a major hurdle to the success of immunotherapy. The immunological mechanisms underlying their development and relation to antitumor responses are poorly understood. By examining both systemic and tissue-specific immune changes induced by combination anti-CTLA-4 and anti-PD-1 immunotherapy, we found distinct repertoire changes in patients who developed moderate-severe colitis, irrespective of their antitumor response to therapy. The proportion of circulating monocytes were significantly increased at baseline in patients who subsequently developed colitis compared with patients who did not develop colitis, and biopsies from patients with colitis showed monocytic infiltration of both endoscopically and histopathologically normal and inflamed regions of colon. The magnitude of systemic expansion of T cells following commencement of immunotherapy was also greater in patients who developed colitis. Importantly, we show expansion of specific T cell subsets within inflamed regions of the colon, including tissue-resident memory CD8+ T cells and Th1 CD4+ T cells in patients who developed colitis. Our data also suggest that CD8+ T cell expansion was locally induced, while Th1 cell expansion was systemic. Together, our data show that exaggerated innate and T cell responses to combination immunotherapy synergize to propel colitis in susceptible patients.

Risk factors for immune-mediated hepatotoxicity in patients with cancer treated with immune checkpoint inhibitors: A systematic review and meta-analysis

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are effective for the treatment of various cancers, but can lead to immune-mediated hepatotoxicity (IMH). The aim of this study was to analyze the risk factors for IMH in cancer patients treated with ICIs.

AREAS COVERED

The PubMed, EMBASE, and Cochrane Library databases were searched. Eligible studies should compare the difference between patients who developed and did not develop IMH. Odds ratio (OR) and weighted mean difference (WMD) with 95% confidence interval (CI) were calculated.

EXPERT OPINION

Among the 5030 papers initially identified, 13 studies were included. Meta-analyses indicated that age (WMD: -5.200, 95%CI: -7.481 to -2.919), history of ICIs treatment (OR: 4.491, 95%CI: 2.205 to 9.145), ICIs combination therapy (OR: 5.353, 95%CI: 1.663 to 17.232), and AST level (WMD: 5.039, 95%CI: 1.220 to 8.857) were significantly associated with the risk of any grade IMH; and age (WMD: -5.193; 95%CI: -9.669 to -0.718) was significantly associated with the risk of grade ≥3 IMH. These findings provide the evidence for identifying patients at a high risk of IMH. Appropriate intervention may be given to prevent from IMH in high-risk patients, thereby enabling ICIs to achieve an expected tumor response.

Multimodal Imaging Response after the Singular or Combination Treatments of Vascular Endothelial Growth Factor Inhibitor and Immune Checkpoint Inhibitor

This study aims to dynamically assess tumor changes after variable treatments with vascular endothelial growth factor (VEGF) inhibitor and/or immune checkpoint inhibitor (ICI) using multimodal imaging of MRI and ¹⁸F-FDG PET/CT in a hepatocellular carcinoma (HCC) mice model. Based on different treatments, 24 mice were randomly divided into four groups: control (isotype-matched IgG antibody 10 mg/kg), VEGF inhibitor (sorafenib 50 mg/kg), ICI (anti-PD-L1 antibody 10 mg/kg), and combination groups (sorafenib 50 mg/kg + anti-PD-L1 antibody 10 mg/kg). Quantitative imaging assessments, including volume transfer constant (K^trans), apparent diffusion coefficient (ADC), lactate/choline ratio, and the maximum standardized ¹⁸F-FDG uptake value ratio of tumor to muscle (SUV_tumor/SUV_muscle ratio), were acquired at different time points (before treatment and 7, 14, and 21 days after treatment). Quantitative data were presented as the mean ± standard errors and two-way repeated-measure ANOVA tests were performed for intergroup and intertime point comparisons. After 21 days from the initiation of therapies, combination group showed the lowest tumor volume and weight, followed by ICI, VEGF inhibitor, and control group, with no significance between the VEGF inhibitor and control groups. In addition, K^trans values significantly decreased, and the lactate/choline ratio and SUV_tumor/SUV_muscle ratio were significantly elevated in the VEGF inhibitor group. ADC significantly increased in the ICI and combination groups, with no significant differences in ADC observed between the control and VEGF inhibitor groups, which showed a similar dynamic change to the tumor volume. Furthermore, K^trans, lactate/choline ratio, and ADC were significantly correlated with CD31⁺ area, hypoxyprobe⁺ area, and apoptosis, respectively. Our results suggest that the singular treatment and combination of the VEGF inhibitor and ICI treatments for HCC present different multimodal imaging changes in accordance with the specific histopathological features. These findings might facilitate the formulation of better treatment response criteria; besides, we find ADC is probably an indicator easily to obtain for treatment response evaluation.

Moderate Colitis Not Requiring IV Steroids Is Associated with Improved Survival in Stage IV Melanoma after Anti-CTLA4 Monotherapy, But Not Combination Therapy

Background

For patients with melanoma, gastrointestinal immune-related adverse events are common after receipt of anti-CTLA4 therapy. These present difficult decision points regarding whether to discontinue therapy. Detailing the situations in which colitis might predict for improved survival and how this is affected by discontinuation or resumption of therapy can help guide clinical decision-making.

Materials and Methods

Patients with stage IV melanoma receiving anti-CTLA4 therapy from 2008 to 2019 were analyzed. Immune-related colitis treated with ≥50 mg prednisone or equivalent daily or secondary immunosuppression was included. Moderate colitis was defined as receipt of oral glucocorticoids only; severe colitis was defined as requiring intravenous glucocorticoids or secondary immunosuppression. The primary outcome was overall survival (OS).

Results

In total, 171 patients received monotherapy, and 91 received dual checkpoint therapy. In the monotherapy group, 25 patients developed colitis and a nonsignificant trend toward improved OS was observed in this group. Notably, when colitis was categorized as none, moderate or severe, OS was significantly improved for moderate colitis only. This survival difference was not present after dual checkpoint therapy. There were no differences in known prognostic variables between groups, and on multivariable analysis neither completion of all ipilimumab cycles nor resumption of immunotherapy correlated with OS, while the development of moderate colitis did significantly affect OS.

Conclusion

This single-institution retrospective series suggests moderate colitis correlates with improved OS for patients with stage IV melanoma treated with single-agent anti-CTLA4, but not dual agent, and that this is true regardless of whether the immune-checkpoint blockade is permanently discontinued.

Immune Checkpoint Inhibitor Rechallenge and Resumption: a Systematic Review

PURPOSE OF THE REVIEW

The reintroduction of immune checkpoint inhibitors (ICIs) after disease progression (rechallenge) or immune-related adverse events (irAEs) recovering (resumption) raises questions in terms of efficacy and safety.

RECENT FINDINGS

Here, we reviewed literature data about ICIs rechallenge/resumption in cancer patients along with their clinical characteristics to explore those factors associated with better outcomes. Heterogenous results were pointed out across rechallenge studies with an overall response rate between 0 and 54%, and a progression free survival ranged from 1.5 to 12.9 months and an overall survival between 6.5 and 23.8 months. Better outcomes have been recorded in patients with good ECOG PS, longer duration of initial ICI, discontinuation reason of initial ICI other than progression, and those who received ICI sequence other than the switch between anti-PD1 and anti-PDL1. Studies about ICI resumption highlighted that certain types of irAEs were more likely to relapse at retreatment. These results suggest that ICI rechallenge/resumption can be an interesting strategy for selected patients.

Clinic, Endoscopic and Histological Features in Patients Treated with ICI Developing GI Toxicity: Some News and Reappraisal from a Mono-Institutional Experience

Background: Immune checkpoint inhibitors (ICIs) have widened the therapeutic scenario of different solid tumors over the last ten years. Gastrointestinal (GI) adverse events (AEs), such as diarrhea and colitis, occur in up to 50% of patients treated with ICIs. Materials and methods: We conducted a single-center retrospective analysis in patients with solid tumors treated with ICIs in a 6-year period, from 2015 to 2021, developing GI AEs, for which an endoscopic analysis was performed, with available histological specimens or surgery. Results: Twenty-one patients developed GI AEs under ICIs. The median time from the start of ICIs to the onset of GI AEs was 5 months. Diarrhea was the most frequent symptom (57.2%), upper GI symptoms presented in four patients (19%), while three patients (14.3%) had no symptoms and were diagnosed occasionally. Two patients underwent surgical resection for acute abdomen. Histological findings observed in endoscopic sampling were eosinophilic-pattern gastro-enterocolitis, apoptotic damage, IBD-like features, and ischemic-like changes. Histological damage was also documented in patients with unremarkable endoscopy. Conclusions: Under ICI therapy, GI toxicity is an expected event. Since GIAEs can mimic a broad range of primary GI diseases, a multidisciplinary approach is advocated with upper and lower GI mucosal sampling to remodel therapy and avoid complications.

18 F-FDG PET/CT features of immune-related adverse events and pitfalls following immunotherapy

¹⁸F‐FDG PET/CT scanning is routinely performed to stage and evaluate the treatment response in many malignancies. Immunotherapy is a rapidly growing treatment option for many cancers, and both clinicians and imaging specialists need to be familiar with ¹⁸F‐FDG PET/CT imaging characteristics unique to patients on this type of treatment. In particular, many immune‐related adverse events (irAEs) can be detected on ¹⁸F‐FDG PET/CT and early accurate identification is critical to reduce treatment related morbidity and incorrect interpretation of malignant disease status. This pictorial essay reviews frequently encountered irAEs in clinical practice and their appearances on ¹⁸F‐FDG PET/CT along with a brief discussion on pseudoprogression and hyperprogression.

Flexible sigmoidoscopy may be sufficient for initial evaluation of suspected immunotherapy-mediated colitis: A cross-sectional study

BACKGROUND AND AIM

Immune checkpoint inhibitors (ICIs) have shown promise in treating a variety of cancers. Their increased use coincides with increased incidence of immunotherapy-mediated colitis (IMC), a common adverse effect. Optimal strategy for endoscopic evaluation of IMC (full colonoscopy or flexible sigmoidoscopy) is not well-defined.

METHODS

Retrospective review of all patients at City of Hope referred to gastroenterology for evaluation of IMC due to gastrointestinal symptoms was performed. Patients with an existing histologic diagnosis of IMC established at an outside hospital or a diagnosis of infectious or chronic colitis were excluded.

RESULTS

We identified 51 symptomatic patients on ICIs prompting evaluation for IMC with colonoscopy (47/51) or flexible sigmoidoscopy (4/51). All distal rectosigmoid biopsies during flexible sigmoidoscopy demonstrated histologic evidence of IMC. In full colonoscopy, IMC was either present in all segments of colon simultaneously (35/47) or absent from all segments (12/47). No isolated proximal colonic biopsies demonstrated IMC. Endoscopically normal mucosa demonstrated histologic evidence of IMC up to 68.6% of the time. Endoscopically abnormal right, transverse, and left colon had low sensitivity (35.3%, 34.3%, and 41.7%, respectively) and high specificity (100.0%, 100.0%, and 91.7%, respectively) for histological presence of IMC.

CONCLUSIONS

Distal colon biopsies in patients on ICI therapy with diarrhea and suspected IMC were sufficient for diagnosing IMC in our cohort. Further, we found histologic evidence of IMC in biopsies taken from normal-appearing mucosa in a number of patients, suggesting that a normal endoscopic appearance does not preclude the presence of IMC and biopsies should be taken from both normal and abnormal-appearing mucosa.

Predicting and Preventing Immune Checkpoint Inhibitor Toxicity: Targeting Cytokines

Cancer immunotherapies can successfully activate immune responses towards certain tumors. However, this can also result in the development of treatment-induced immune-related adverse events (irAEs) in multiple tissues. Growing evidence suggests that cytokine production in response to these therapeutics potentiates the development of irAEs and may have predictive value as biomarkers for irAE occurrence. In addition, therapeutic agents that inhibit cytokine activity can limit the severity of irAEs, and their use is being tested in the clinical setting. This review provides an in-depth analysis of strategies to uncouple the cytokine response, that precipitates irAEs following cancer immunotherapies, from the benefit gained in promoting antitumor immunity.