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Purpose: Immune checkpoint inhibitor (ICI) therapy is often suspended because of immune-related enterocolitis (irEC). We examined the effect of resumption of ICIs with or without concurrent selective immunosuppressive therapy (SIT) on rates of symptom recurrence and survival outcomes., Methods: This retrospective, multicenter study examined patients who were treated with ICI and developed irEC requiring SIT (infliximab or vedolizumab) for initial symptom control or to facilitate steroid tapering between May 2015 and June 2020. After symptom resolution, patients were restarted either on ICI alone or on concurrent ICI and SIT at the discretion of the treating physicians. The associations between irEC recurrence and treatment group were assessed via univariate analyses and multivariate logistic regression. Cox proportional hazards model was used for survival analysis., Results: Of the 138 included patients who required SIT for initial irEC symptom control, 61 (44.2%) patients resumed ICI without concurrent SIT (control group) and 77 (55.8%) patients resumed ICI therapy with concurrent SIT: 33 with infliximab and 44 with vedolizumab. After symptom resolution, patients in the control group were more commonly restarted on a different ICI regimen (65.6%) compared with those receiving SIT (31.2%) (p<0.001). The total number of ICI doses administered after irEC resolution and ICI resumption was similar in both groups (four to five doses). Recurrence of severe colitis or diarrhea after ICI resumption was seen in 34.4% of controls compared with 20.8% of patients receiving concurrent SIT. Concurrent SIT was associated with reduced risk of severe irEC recurrence after ICI resumption in a multivariate logistic regression model (OR 0.34; 95% CI 0.13 to 0.92; p=0.034). There was no difference in survival outcomes between patients in the control group and patients concurrently treated with SIT., Conclusion: After resolution of irEC symptoms, reinitiation of ICI with concurrent SIT is safe, reduces severe irEC recurrence, and has no negative impact on survival outcomes., Competing Interests: Competing interests: Unrelated to this work, YRB has consulting fees from Aditum Bio and Goodpath. MD has research funding from Novartis and Eli Lilly, has received consulting fees from Tillotts Pharma, ORIC Pharmaceuticals, Partner Therapeutics, SQZ Biotech, AzurRx, Mallinckrodt Pharmaceuticals, and Moderna, and is a member of the Scientific Advisory Board for Neoleukin Therapeutics. DF has received consulting fees from Kaleido Biosciences, AzurRx, Mallinckrodt Pharmaceuticals, and Equillium. MP has received consulting fees from BMS, Merck, Array BioPharma, Novartis, Incyte, NewLink Genetics, Aduro, Eisai, Pfizer; honoraria from BMS and Merck; institutional support from RGenix, Infinity, BMS, Merck, Array BioPharma, Novartis, and AstraZeneca., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Recombinant granulocyte colony-stimulating factor (G-CSF) is routinely administered for prophylaxis or treatment of chemotherapy-induced neutropenia. Chronic myelopoiesis and granulopoiesis in patients with cancer has been shown to induce immature monocytes and neutrophils that contribute to both systemic and local immunosuppression in the tumor microenvironment. The effect of recombinant G-CSF (pegfilgrastim or filgrastim) on the production of myeloid-derived suppressive cells is unknown. Here we examined patients with pancreatic cancer, a disease known to induce myeloid-derived suppressor cells (MDSCs), and for which pegfilgrastim is routinely administered concurrently with FOLFIRINOX but not with gemcitabine-based chemotherapy regimens., Methods: Serial blood was collected from patients with pancreatic ductal adenocarcinoma newly starting on FOLFIRINOX or gemcitabine/n(ab)paclitaxel combination chemotherapy regimens. Neutrophil and monocyte frequencies were determined by flow cytometry from whole blood and peripheral blood mononuclear cell fractions. Serum cytokines were evaluated pretreatment and on-treatment. Patient serum was used in vitro to differentiate healthy donor monocytes to MDSCs as measured by downregulation of major histocompatibility complex II (HLA-DR) and the ability to suppress T-cell proliferation in vitro. C57BL/6 female mice with pancreatic tumors were treated with FOLFIRINOX with or without recombinant G-CSF to directly assess the role of G-CSF on induction of immunosuppressive neutrophils., Results: Patients receiving FOLFIRINOX with pegfilgrastim had increased serum G-CSF that correlated with an induction of granulocytic MDSCs. This increase was not observed in patients receiving gemcitabine/n(ab)paclitaxel without pegfilgrastim. Interleukin-18 also significantly increased in serum on FOLFIRINOX treatment. Patient serum could induce MDSCs as determined by in vitro functional assays, and this suppressive effect increased with on-treatment serum. Induction of MDSCs in vitro could be recapitulated by addition of recombinant G-CSF to healthy serum, indicating that G-CSF is sufficient for MDSC differentiation. In mice, neutrophils isolated from spleen of G-CSF-treated mice were significantly more capable of suppressing T-cell proliferation., Conclusions: Pegfilgrastim use contributes to immune suppression in both humans and mice with pancreatic cancer. These results suggest that use of recombinant G-CSF as supportive care, while critically important for mitigating neutropenia, may complicate efforts to induce antitumor immunity., Competing Interests: Competing interests: SKD received research funding unrelated to this project from Eli Lilly and Company, Novartis Pharmaceuticals, Genocea, and Bristol-Myers Squibb and is a founder, science advisory board member and equity holder in Kojin. MD has research funding from Eli Lilly; he has received consulting fees from Genentech, ORIC Pharmaceuticals, Partner Therapeutics, SQZ Biotech, AzurRx, Eli Lilly, Mallinckrodt Pharmaceuticals, Aditum, Foghorn Therapeutics, Palleon, and Moderna; and he is a member of the Scientific Advisory Board for Neoleukin Therapeutics, Veravas and Cerberus Therapeutics. HS receives research funding from AstraZeneca and consulting fees from Merck and Dewpoint Therapeutics. DAR is on the scientific advisory board of AxialTx and a consultant for Boston Scientific and Instylla. MBY receives research funding from Janssen Oncology and fees for peer review services from UpToDate. NJM receives research funding from Bristol-Myers Squibb. PCE has received consulting fees from ALX Oncology, Arcus Bioscience, Astellas, AstraZeneca, Blueprint Medicines, Celgene, Coherus, Daiichi-Sankyo, Five Prime, Ideaya, Istari, Legend, Lilly, Loxo, Merck, Novartis, Ono, Servier, Taiho, Takeda, Turning Point, Therapeutics, Xencor, and Zymeworks. KN received research funding from Pharmavite, Evergrande Group, Janssen, Revolution Medicines and is on the SAB or received consulting fees from Bayer, GlaxoSmithKline, and Pfizer. BMW receives consulting fees from Celgene, GRAIL, and Mirati and research support from Celgene, Eli Lilly, Novartis, and Revolution Medicines., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: In 2017, Massachusetts General Hospital implemented the Severe Immunotherapy Complications (SIC) Service, a multidisciplinary care team for patients hospitalized with immune-related adverse events (irAEs), a unique spectrum of toxicities associated with immune checkpoint inhibitors (ICIs). This study's objectives were to evaluate the intervention's (1) effect on patient outcomes and healthcare utilization, and (2) ability to collect biological samples via a central infrastructure, in order to study the mechanisms responsible for irAEs., Methods: A hospital database was used to identify patients who received ICIs for a malignancy and were hospitalized with severe irAEs, before (April 2, 2016-October 3, 2017) and after (October 3, 2017-October 24, 2018) SIC Service initiation. The primary outcome was readmission rate after index hospitalization. Secondary outcomes included length of stay (LOS) for admissions, corticosteroid and non-steroidal second-line immunosuppression use, ICI discontinuation, and inpatient mortality., Results: In the pre-SIC period, 127 of 1169 patients treated with ICIs were hospitalized for irAEs; in the post-SIC period, 122 of 1159. After SIC service initiation, reductions were observed in irAE readmission rate (14.8% post-SIC vs 25.9% pre-SIC; OR 0.46; 95% CI 0.22 to 0.95; p=0.036) and readmission LOS (median 6 days post-SIC vs 7 days pre-SIC; 95% CI -16.03 to -0.14; p=0.046). No significant pre-initiation and post-initiation differences were detected in corticosteroid use, second-line immunosuppression, ICI discontinuation, or inpatient mortality rates. The SIC Service collected 789 blood and tissue samples from 234 patients with suspected irAEs., Conclusions: This is the first study to report that establishing a highly subspecialized care team focused on irAEs is associated with improved patient outcomes and reduced healthcare utilization. Furthermore, the SIC Service successfully integrated blood and tissue collection safety into routine care., Competing Interests: Competing interests: LZ—Merck consultant. JC—consultant for BMS and Sanofi-Genzyme. DJ—scientific advisory board fee from Eisai, EMD Serono, Genentech, Ipsen, Novartis, Guardant, Petra Pharma, Mapkure, Vibliome Therapeutics, and Relay Therapeutics; institutional research funds from Novartis, Genentech, EMD Serono, Eisai, Takeda, Placon Therapeutics, Syros, Ribon Therapeutics, Infinity Pharmaceuticals, InventisBio and Amgen. GMB—sponsored research agreements with Palleon Therapeutics and Olink Proteomics; scientific advisory board for Novartis and Nektar Therapeutics; consulting for Merck. MD—consultant for Moderna, Tillotts Pharma, ORIC Pharmaceuticals, and Partner Therapeutics; research funding from Novartis and Eli Lilly; scientific advisory board for Neoleukin Therapeutics. ACG—consultant for Momenta, Alexion, UCB/Ra pharma; royalties from Oakstone Publishing; research funding from Myasthenia Gravis Foundation of America, MGNET and Project Datasphere. BDM—consultant for Sanofi, AbbVie, and Celestial Pharmaceuticals. He has also received sponsored research agreements from Boehringer-Ingelheim, Bayer, and Bristol-Myers Squib. MK—consultant for Novartis and Mymee; speaker fees for Lilly. TGN—advisory fees from Parexel, BMS, H3 Biomedicine, AbbVie, and Intrinsic Imaging; grant support from AstraZeneca. JRF—research grants from Bristol Myers Squibb and X4 Pharmaceuticals. MJM—received honarium/acted as a consultant for AstraZeneca, Nektar Therapeutics, Catalyst Pharmaceuticals, Immunai Aditya Bardia; consulting or advisory role for bioTheranostics, Genentech, Genentech/Roche (Inst), Immunomedics, Immunomedics (Inst), Innocrin Pharma (Inst), Merck, Merck (Inst), Novartis, Novartis (Inst), Pfizer, Pfizer (Inst), Radius Health (Inst), Radius Pharma, Sanofi, Spectrum Pharmaceuticals; research funding from bioTheranostics. RS—consultant/scientific advisory board member for AstraZeneca, Bristol-Myers Squibb, Eisai, Iovance, Merck, Novartis, OncoSec, Pfizer, Replimune; research funding from Merck and Amgen. SB—consultant for Third Rock Consulting and Two River Consulting; equity holdings in Kronos Bio and Allogene Therapeutics. YRS—consultant for Castle Biosciences., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer, improving outcomes in patients with advanced malignancies. The use of ICIs in clinical practice, and the number of ICI clinical trials, are rapidly increasing. The use of ICIs in combination with other forms of cancer therapy, such as chemotherapy, radiotherapy, or targeted therapy, is also expanding. However, immune-related adverse events (irAEs) can be serious in up to a third of patients. Critical questions remain surrounding the characteristics and outcomes of irAEs, and how they may affect the overall risk-benefit relationship for combination therapies. This article proposes a framework for irAE classification and reporting, and identifies limitations in the capture and sharing of data on irAEs from current clinical trial and real-world data. We outline key gaps and suggestions for clinicians, clinical investigators, drug sponsors, patients, and other stakeholders to make these critical data more available to researchers for pooled analysis, to advance contemporary understanding of irAEs, and ultimately improve the efficacy of ICIs., Competing Interests: Competing interests: KLR receives support from Teladoc and Project Data Sphere. MR owns shares of Pfizer Inc. ACG has served on advisory boards/consulted with Alexion, RA Pharma (UCB), and Momenta (Jansen). She also receives support from Project Data Sphere. MD has received support from Novartis, Eli Lilly, Moderna, Tillotts Pharma, ORIC Pharmaceuticals, and Partner Therapeutics. He is engaged with Moderna and Neoleukin Therapeutics. LZ has received support from Merck US. DBJ has received support from BMS and Incyte and serves on advisory boards for Array Biopharma, BMS, Catalyst, Iovance, Jansen, Merck, Novartis, and Oncosec. OR has received support from Merck, Celgene, Five Prime, GSK, Bayer, Roche, Puretech, Imvacx, and Sobi, has an immunotherapy patent pending, and serves as CMO of Outcomes4me., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Expanding the US Food and Drug Administration-approved indications for immune checkpoint inhibitors in patients with cancer has resulted in therapeutic success and immune-related adverse events (irAEs). Neurologic irAEs (irAE-Ns) have an incidence of 1%-12% and a high fatality rate relative to other irAEs. Lack of standardized disease definitions and accurate phenotyping leads to syndrome misclassification and impedes development of evidence-based treatments and translational research. The objective of this study was to develop consensus guidance for an approach to irAE-Ns including disease definitions and severity grading. A working group of four neurologists drafted irAE-N consensus guidance and definitions, which were reviewed by the multidisciplinary Neuro irAE Disease Definition Panel including oncologists and irAE experts. A modified Delphi consensus process was used, with two rounds of anonymous ratings by panelists and two meetings to discuss areas of controversy. Panelists rated content for usability, appropriateness and accuracy on 9-point scales in electronic surveys and provided free text comments. Aggregated survey responses were incorporated into revised definitions. Consensus was based on numeric ratings using the RAND/University of California Los Angeles (UCLA) Appropriateness Method with prespecified definitions. 27 panelists from 15 academic medical centers voted on a total of 53 rating scales (6 general guidance, 24 central and 18 peripheral nervous system disease definition components, 3 severity criteria and 2 clinical trial adjudication statements); of these, 77% (41/53) received first round consensus. After revisions, all items received second round consensus. Consensus definitions were achieved for seven core disorders: irMeningitis, irEncephalitis, irDemyelinating disease, irVasculitis, irNeuropathy, irNeuromuscular junction disorders and irMyopathy. For each disorder, six descriptors of diagnostic components are used: disease subtype, diagnostic certainty, severity, autoantibody association, exacerbation of pre-existing disease or de novo presentation, and presence or absence of concurrent irAE(s). These disease definitions standardize irAE-N classification. Diagnostic certainty is not always directly linked to certainty to treat as an irAE-N (ie, one might treat events in the probable or possible category). Given consensus on accuracy and usability from a representative panel group, we anticipate that the definitions will be used broadly across clinical and research settings., Competing Interests: Competing interests: ACG has served on an advisory board and/or consulted with Alexion, Ra Pharma/UCB and Momenta pharmaceuticals/Janssen. She has received royalties from Oakstone Publishing and research support from the Myasthenia Gravis Foundation of America, the MG Rare Disease Network and Project Data Sphere® for an irAE-N registry. She has received clinical trial support to the institution from Ra Pharma and Momenta. LBB receives salary support from Biogen, royalties from Oakstone Publishing, and research support from Project Data Sphere for an irAE-N registry. BKC reports research support from Project Data Sphere for an irAE-N registry. JH receives research support from Project Data Sphere for an irAE-N registry and from GE Healthcare. THS is an employee at the not-for-profit corporation Project DS, with a trade name of Project Data Sphere. AAA served on medical advisory boards for Alexion, Sarepta, CSL Behring, Strongbridge Pharma, Argenx, Ra Pharmaceuticals, and as a neurology consultant for Johnson & Johnson COVID-19 vaccine trials. ABW served on a medical advisory board or as a consultant with Iovance, Novartis, Shanghai Jo’Ann Medical Technology. PKB has consulted for Angiochem, Genentech-Roche, Lilly, Tesaro, Voyager Therapeutics, ElevateBio, Pfizer (Array), Pfizer, SK Life Sciences and Dantari, received grant/research support (to Massachusetts General Hospital) from Merck, BMS and Lilly and honoraria from Merck, Pfizer, Genentech-Roche and Lilly. TAC has received royalties from Wolters Kluwer. SLC serves as the Editor of the Neurology®Podcast and Neurology Minute™. She has received research and/or clinical fellowship support from the Western Institute for Veterans Research, the Siegel Rare Neuroimmune Association, the Immune Deficiency Foundation, Alexion, the Barbara Gural Steinmetz Foundation, and the Sumaira Foundation for NMO. She has served on an advisory board and/or consulted with Alexion, Genentech, VielaBio, Guidepoint, Clarion Healthcare Consulting, ExpertConnect (majority fees paid to University of Utah). JC has received consulting fees from Sanofi-Genzyme and BMS. JD is a consultant for Blue Earth Diagnostics, Magnolia, Gamaka Bio, and Unum Therapeutics. JD has received research support from Beacon Biosignals, Boehringer Ingelheim, Brystol-Myers Squibb, Eli Lilly, Medimmune, Acerta Pharma, Orbus Therapeutics, and Novartis Pharmaceuticals. JD has received royalties from Wolters Kluwer for serving as an author for UpToDate. MD has research funding from Novartis and Eli Lilly, has served as a consultant for Roche-Genentech, Tillotts Pharma, ORIC Pharmaceuticals, Partner Therapeutics, and Moderna, and is a member of the Scientific Advisory Board for Neoleukin Therapeutics. CTD has served on advisory boards for Argenx and Dysimmune Diseases Foundation. He has received royalties from Oakstone Publishing. He has received grant support from NINDS/NeuroNext. DD has served on an advisory board and/or consulted for UCB, Astellas and Immunovant pharmaceuticals. All compensation for the consulting activities is paid to Mayo Clinic. He has patents pending for KLHL11 and LUZP4 as markers of neurological autoimmunity and germ cell tumors. JG has received research to UCSF support from Genentech/Roche for a clinical trial, performed consulting for Biogen, and received personal compensation for medical-legal consulting. JTG has served as a consultant in past 12 months for Immunovant, Alexion, Momenta, Ra Pharma, Grifols, Jacobus, Cabaletta, Regeneron, Argenx, Signant, UCB, Toleranzia and Piedmont Pharmaceuticals. He receives industry grant support from UCB pharma for a fellowship training grant. Full disclosure statement available at: https://dcri.org/about-us/conflict-of-interest/. DBJ has served on advisory boards for Array Biopharma, BMS, Catalyst Biopharma, Iovance, Jansen, Merck, Novartis, and Oncosec, and has received research funding from BMS and Incyte. VCJ is a site investigator in myasthenia gravis research trials sponsored by PCORI and by Alexion Pharmaceuticals. RK receives research funding from Alexion Pharmaceuticals. NK reports no relevant disclosures. NRL is a consultant and has received honoraria from Bayer, Seattle Genetics, Sanofi, Fortress Biotech, Silverback Therapeutics and SYNOX Therapeutics. JL reports no disclosures. AM reports no disclosures. MM-L reports no relevant disclosures. MJM has served on an advisory board and/or consulted with AstraZeneca Pharmaceuticals, Nektar Therapeutics, Catalyst Pharmaceuticals and Immunai. JN has received research funding from Merck and AstraZeneca; served as a consultant/advisory board member with Merck, AstraZeneca, BMS, Pfizer, Takeda, Roche/Genentech, Daiichi/Sankyo and has received honoraria from Merck, AstraZeneca, BMS, Pfizer, Takeda, Roche/Genentech. TGN reports acting as a consultant for Parexel, Bristol Myers-Squibb, H3 Biomedicine, AbbVie, and Intrinsic Imaging unrelated to the current research. TGN reports grant funding from AstraZeneca unrelated to current research. DR has been an advisor or consultant with AbbVie; Advantagene; Agenus; Agios; Amgen; Bayer; Boston Biomedical; Boehringer Ingelheim; Bristol-Myers Squibb; Celldex; Deciphera; DelMar; EMD Serono; Genenta; Genentech/Roche; Imvax; Inovio; Kintara; Kiyatec; Medicenna Biopharma; Merck; Merck KGaA; Monteris; Neuvogen; Novartis; Novocure; Oncorus; Oxigene; Regeneron; Stemline; Sumitono Dainippon Pharma; Taiho Oncology. Research support to his institution has been provided by Acerta Phamaceuticals; Agenus; Celldex; EMD Serono; Incyte; Inovio; Omniox; Tragara. KMR has served on an advisory board and/or consulted with Merck, BMS, and Eisai. BDS has served on an advisory board and/or consulted with Janssen, Kite/Gilead, and Celgene/BMS. RS has served on an advisory board and/or consulted with AstraZeneca, Bristol-Myers Squib, Eisai, Iovance, Merck, Novartis, Oncosec, Pfizer, and Replimune. He has received research funding from Merck. NW has served on an advisory board with Seattle Genetics, received royalties from Wolters Kluwer and research support from Merck. KW reports no disclosures. LZ has been a consultant for Merck. WCL is an employee of the not-for-profit corporation Project DS, with a trade name of Project Data Sphere. KLR has received personal compensation from Teladoc research support from Project Data Sphere for a irAE-N registry., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aims: Immune checkpoint inhibitor (ICI) enterocolitis is a common immune-related adverse event and can be fatal, especially when not diagnosed and treated promptly. The current gold standard for diagnosis is endoscopy with biopsy, but CT scan is a possible alternative. The primary objective of this study is to identify the diagnostic performance of CT in the evaluation of ICI enterocolitis., Methods: With institutional review board approval, we conducted a retrospective cohort study of patients who received ICI therapy between 2015 and 2019 across a healthcare system. Patients were included if they underwent both abdominal CT and endoscopy with biopsy within 3 days. The radiological and pathological diagnoses, as well as clinical characteristics, were extracted from the electronic medical record. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CT for diagnosing ICI enterocolitis when compared with tissue diagnosis., Results: Of the 4474 patients screened, 138 met inclusion criteria. Most common tumor types were melanoma (37%) and lung cancer (19%). Seventy-four per cent were treated with antiprogrammed cell death (PD-1)/PD-L1 therapy. Thirty-nine per cent had signs of enterocolitis on CT scan and 58% had biopsy-proven ICI enterocolitis. Sensitivity and specificity of CT were 50% and 74%, respectively. PPV was 73% and NPV was 52%. Of those with confirmed ICI enterocolitis, 70% had grade 3 or higher symptoms, 91% received steroids and 40% received infliximab., Conclusion: The performance of CT scan for diagnosis of ICI enterocolitis is moderate to poor and does not replace endoscopy with biopsy., Competing Interests: Competing interests: MJM. is a consultant and received honoraria from AstraZeneca. MD is a consultant for Tillotts Pharma, Partner Therapeutics, ORIC Pharmaceuticals, and Genentech-Roche, receives research funding from Novartis, and is on the Scientific Advisory Board for Neoleukin. All other authors declare no competing interests., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Rare cases of immune checkpoint inhibitor (ICI)-associated celiac disease (ICI-CeD) have been reported, suggesting that disruption of tolerance mechanisms by ICIs can unmask celiac disease (CeD). This study aims to characterize the clinicopathological and immunophenotypic features of ICI-CeD in comparison to ICI-associated duodenitis (ICI-Duo) and usual CeD., Methods: A medical and pathological records search between 2015 and 2019 identified eight cases of ICI-CeD, confirmed by tTG-IgA. Nine cases of ICI-Duo, 28 cases of moderate CeD, as well as 5 normal controls were used as comparison groups. Clinical information was collected from the electronic medical records. Immunohistochemistry for CD3, CD8, T-cell receptor gamma/delta (γδ), programmed death ligand 1 (PD-L1), and programmed death 1 (PD-1) were performed, with quantification of intraepithelial lymphocyte (IEL) subsets in three well-oriented villi. CD68, PD-L1, and PD-1 were assessed as a percentage of lamina propria surface area infiltrated by positive cells. Statistical significance was calculated by the Student's t-test and Fisher's exact test., Results: The eight patients with ICI-CeD (F:M=1:3) and nine patients with ICI-Duo (F:M=5:4) presented similarly with diarrhea (13/17) and abdominal pain (11/17) after a median of 1.6 months on ICI therapy. In patients with ICI-CeD, tTG-IgA ranged from 104 to >300 IU/mL. Histological findings in ICI-CeD and ICI-Duo were similar and included expansion of the lamina propria, active neutrophilic duodenitis, variably increased IELs, and villous blunting. Immunohistochemistry showed that the average number of IELs per 100 enterocytes is comparable between ICI-CeD and ICI-Duo, with increased CD3 + CD8 + T cells compared with normal duodenum but decreased γδ T cells compared with CeD. Average PD-L1 percentage was 9% in ICI-CeD and 18% in ICI-Duo, in comparison to <1% in CeD and normal duodenum; average PD-1 percentage was very low to absent in all cases (<3%). On follow-up, five patients with ICI-CeD improved on a gluten-free diet (GFD) as the sole therapeutic intervention (with down-trending tTG-IgA) while the other three required immunosuppression. All patients who developed ICI-Duo received immunosuppression with variable improvement in symptoms., Conclusions: ICI-CeD resembles ICI-Duo clinically and histologically but shares the serological features and response to gluten withdrawal with classic CeD. Immunophenotyping of IELs in ICI-CeD and ICI-Duo also shows similar CD3, CD8, γδ T cell subsets, and PD-L1 populations, all of which differed quantitatively from usual CeD. We conclude that ICI-CeD is biologically similar to ICI-Duo and is likely a variant of ICI-Duo, but treatment strategies differ, with ICI-CeD often improving with GFD alone, whereas ICI-Duo requires systemic immunosuppression., Competing Interests: Competing interests: MD is a consultant for Genentech-Roche, Tillotts Pharma, and Partner Therapeutics. He received research funding from Novartis. He is on the scientific advisory board for Neoleukin Therapeutics., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.)

Background: Immune-related colitis is a common, often serious complication of immune checkpoint inhibition (ICI). Although endoscopy is not strictly recommended for any grade of diarrhea/colitis, emerging evidence suggests that endoscopic evaluation may have important therapeutic implications. In this retrospective study, we sought to comprehensively characterize the clinical and histologic features of ICI-induced colitis with a specific focus on evaluating the prognostic role of endoscopy., Methods: Data were collected from the medical records of 130 patients with confirmed ICI-induced colitis. In a subset of patients (n=44) with endoscopic and pathologic data, endoscopic data were scored using the Mayo Endoscopic Score (MES) with scores ranging from 0 (no inflammation) to 3 (colonic ulceration). The impact of infliximab on antitumor outcomes was evaluated using progression-free survival (PFS) and overall survival (OS)., Results: We identified 130 patients with ICI-induced colitis across two institutions. All patients were treated with corticosteroids. Additional and/or alternative immunosuppression was employed in 59 cases, with 52 patients (42%) requiring at least one infusion of infliximab 5 mg/kg. Endoscopic assessment with biopsy was performed in 123 cases of suspected colitis (95%), with 44 cases available for MES tabulation. Presence of ulceration (MES 3) was associated with use of infliximab (p=0.008) and MES was significantly higher in patients who received infliximab compared with those who did not (p=0.003) with a median score of 2.5; conversely, those with an MES of zero rarely required secondary immunosuppression. Notably, symptoms of colitis based on Common Terminology Criteria for Adverse Events grade had no association with endoscopic findings based on MES classification. After adjustment for baseline patient and disease characteristics, there was no significant difference in steroid duration or cancer-related outcomes in patients treated with infliximab., Conclusions: In our study, we demonstrate the association of endoscopic features, specifically the MES, with immunosuppressive needs. Importantly, we also show that MES was not related to severity of patient symptoms. The data suggest that endoscopic features can guide clinical decision-making better than patient symptoms, both identifying high-risk patients who will require infliximab and those who are likely to respond to initial corticosteroids., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Immune checkpoint inhibitors (CPIs) are effective against a variety of malignancies but can be limited by inflammatory toxicities such as enterocolitis. Enterocolitis is typically treated with systemically active glucocorticoids. Endoscopy can stratify patients by the severity of mucosal inflammation, including identifying patients with colitis in the absence of visible mucosal changes: microscopic colitis. Whether patients with CPI microscopic colitis could be managed differently from colitis with more severe mucosal involvement is unclear. The objective of this study was to describe outcomes in CPI microscopic colitis focusing on the response to first line treatment with budesonide., Methods: We evaluated data from a retrospective cohort from a single-center large academic hospital. The participants were all adult patients evaluated by endoscopy for suspected CPI enterocolitis between 3/2017 and 3/2019. The exposures were: Mayo Endoscopic Score (range 0-3). The subset was: oral budesonide, maximum dose 12 mg daily, administered minimum of 5 weeks. The main outcomes and measures were: Primary: time from first CPI exposure to first glucocorticoid use; use of systemic glucocorticoids; time from symptom onset to resolution; continuation of CPI therapy; number of additional CPI infusions received. Secondary: admissions for symptom control; novel irAE development; need for second-line immunosuppression; oncologic outcomes., Results: We identified 38 patients with biopsy confirmed CPI enterocolitis, 13 in the microscopic colitis cohort, and 25 in the non-microscopic colitis cohort. Budesonide use was higher in the microscopic colitis cohort (12/13 vs 3/25, p < 0.001), and systemic glucocorticoid use was higher in non-microscopic colitis (22/25 vs. 3/13, p < 0.001). Time from symptom onset to resolution did not differ. Microscopic colitis patients more frequently remained on CPI after developing (entero)colitis (76.9% vs 16.0%, p < 0.001). Microscopic colitis patients tolerating further CPI received, on average, 4.2 CPI infusions more than non-microscopic colitis patients tolerating CPI (5.8 vs 1.6, p = 0.03). Microscopic colitis was associated with increased time-to-treatment-failure (HR 0.30, 95% CI 0.14-0.66) and progression-free survival (HR 0.22, 95% CI 0.07-0.70)., Conclusions: Gastrointestinal mucosal inflammation without visible mucosal injury is a distinct, prevalent CPI enterocolitis subset that can be diagnosed by endoscopy. First-line budesonide appears effective in controlling "microscopic colitis" symptoms and prolonging immunotherapy duration. These findings present a compelling rationale for routine endoscopic evaluation of suspected CPI enterocolitis and suggest an alternative glucocorticoid-sparing treatment strategy for a subset of such patients.

Background: Immune checkpoint inhibitors (ICI) have demonstrated remarkable efficacy as cancer therapeutics, however, their use remains limited due to the development of immune related adverse events (irAEs). Immune related enterocolitis (irEC) is among the most common severe irAEs leading to the discontinuation of ICIs. Inhibitors of tumor necrosis factor alpha (anti-TNFα) have been used to treat irEC. Recent animal studies have shown that concurrent treatment with anti-TNFα and ICIs improves tumor responses and decreases colitis severity. This approach has not yet been studied in prospective trials in humans. Here we describe, for the first time, the outcomes of patients who were treated concurrently with anti-TNFα and one or two ICIs., Case Presentations: Five patients with different primary malignancies were treated with ipilimumab/nivolumab (2 patients), pembrolizumab (1 patient), ipilimumab (1 patient), or cemiplimab (1 patient). All patients developed irEC within 40 days of their first ICI dose. The patients presented with a combination of upper and lower gastrointestinal symptoms and subsequently underwent upper endoscopy and/or lower endoscopy. Endoscopy results demonstrated a spectrum of acute inflammatory changes across the gastrointestinal tract. Steroid therapy was used as first line treatment. To prevent prolonged steroid use and recurrence of gastrointestinal inflammation after resumption of cancer therapy, patients were treated concurrently with infliximab and ICI. Patients tolerated further ICI therapy with no recurrence of symptoms. Repeat endoscopies showed resolution of acute inflammation and restaging imaging showed no cancer progression., Conclusions: Concurrent treatment with anti-TNFα and ICI appears to be safe, facilitates steroid tapering, and prevents irEC. Prospective clinical trials are needed to assess the outcomes of this treatment modality.

Background: Alongside its clinical success, checkpoint blockade has also given rise to a set of immune-related adverse events (irAEs). In addition to causing considerable morbidity and even mortality, irAEs may limit the success and scope of immunotherapy. Most irAEs arise at mucosal barriers, including the gastrointestinal mucosa, leading most commonly to colitis, though both gastritis and enteritis can result from checkpoint blockade. While guidelines generally recommend confirmatory testing for suspected severe irAEs, the role of endoscopy in diagnosing more moderate irAEs is less clear. Many patients with suspected gastrointestinal irAEs are treated empirically with glucocorticoids based on typical symptoms. Although efficient, this approach may miss less common underlying etiologies, and may expose patients unnecessarily to an increased risk of infection, and a potentially dampened antitumor response., Case Presentation: We report a case of ipilimumab-induced antitumor immunity targeting microscopic gastric melanoma metastases, mimicking checkpoint blockade induced gastritis. Immune suppression was avoided and the immunotherapy was continued., Conclusion: Checkpoint blockade can induce rapid inflammatory responses to tumor tissue present throughout the body. These responses are desirable, but may also lead to local tissue injury, causing symptoms that may mimic adverse events. This is particularly important to consider in organs where metastatic disease may be unappreciated at the time of treatment, and where irAEs are otherwise common, such as the gastrointestinal tract. In this setting, empiric immune suppression may inhibit antitumor responses, improving symptoms but at a potential cost to therapeutic efficacy.