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Pardi, Darrell S.

https://orcid.org/0000-0003-0420-8784

Mayo Clinic

Mayo Clinic

Citations 117

Effect of peripartum Clostridioides difficile infection on pregnancy and neonatal outcomes: an observational study
Saha, Srishti , Pardi, Ryan, Theiler, Regan N. , Pardi, Darrell S. , Khanna, Sahil , Theiler, Regan

Therapeutic Advances in Gastroenterology | April 27, 2023 | Volume: 16 | Issue: No issue available | Pages: No page available

10.1177/17562848231170479 Get It

Background: The incidence of Clostridioides difficile infection (CDI) in peripartum women is rising, but limited data on its effect on maternal and neonatal outcomes are available. Objective: To study the effect of peripartum CDI on pregnancy and neonatal outcomes. Design: Retrospective cohort study. Methods: Patients with peripartum CDI 12 weeks before pregnancy through 6 weeks postpartum (January 1996–February 2018) were matched with controls (peripartum women without CDI) 1:1 by age, year of delivery, and prior pregnancies. McNemar’s test and conditional logistic regression were used to analyze the effect of CDI on pregnancy and neonatal outcomes (complications, mode of delivery). p < 0.05 was considered statistically significant. Results: Overall, 101 cases and 100 controls (1997–2018) were included; median age 27 (range, 20–41) years. Timing of CDI was as follows: pre-pregnancy: 15.8% ( n = 16), during pregnancy: 51.5% ( n = 52), and postpartum: 32.7% ( n = 33). The commonest risk factor was outpatient/emergency room visits. Pregnancy and neonatal outcomes were analyzed for 67 matched pairs with CDI before or during pregnancy. Cases had higher odds of cesarean delivery ( p = 0.02) and lower odds of Group B Streptococcus (GBS) infection/colonization ( p = 0.03). Odds of cesarean delivery remained high after controlling for labor arrest disorders [odds ratio (OR): 17.23 (95% confidence interval (CI), 2.19–543.19; p = 0.004)]; odds of GBS remained low after controlling for antibiotic use (OR: 0.25, 95% CI, 0.04–0.99; p = 0.049). Neonatal outcomes were similar in cases and controls. CDI treatment did not affect treatment-related or delivery outcomes. Conclusion: Peripartum CDI was associated with higher odds of cesarean delivery and lower odds of GBS infections. Larger studies exploring the effect of CDI on pregnancy and neonatal outcomes are needed.
The natural history of histological changes in microscopic colitis
Sehgal, Kanika , Tome, June , Kamboj, Amrit K. , Dierkhising, Ross , Pardi, Darrell S. , Khanna, Sahil , Tome, June

Therapeutic Advances in Gastroenterology | April 27, 2023 | Volume: 16 | Issue: No issue available | Pages: No page available

10.1177/17562848231168237 Get It

Background: Microscopic colitis (MC) causes chronic diarrhea. It has two histologic subtypes: lymphocytic colitis (LC) and collagenous colitis (CC). Little is known about the natural progression of disease with time and with treatment. Objectives: We aimed to assess histological changes over time. Design: We designed a retrospective study including adults diagnosed with MC from January 1992 to January 2020 at Mayo Clinic. Methods: Pathology reports were reviewed until 31 October 2020. Histological assessments at least 8 weeks apart were considered as adequate follow-up. Histological change from one subtype to the other and resolution were tracked with univariate and multivariable Cox proportional hazards models. Results: Overall, 416 patients with a median age at diagnosis of 63.9 years with >1 histopathological assessment were identified. Histology at initial diagnosis was CC in 218 (52.4%) patients and LC in 198 (47.6%). No medications were associated with a histological change. However, histological resolution was more likely with the use of aspirin [hazard ratio (HR): 2.10, 95% confidence interval (CI): 1.34–3.31, p = 0.001) and proton-pump inhibitors (PPIs; HR: 2.01, 95% CI: 1.34–3.02, p = 0.001). Histological resolution was more likely with budesonide treatment (HR: 1.86, 95% CI: 1.16–3.00, p = 0.010) and less likely with mesalamine (HR: 0.40, 95% CI: 0.19–0.83, p = 0.014), compared to medications such as prednisone, loperamide, and bismuth. Patients with CC were less likely to change their histology compared to patients with LC (HR: 0.24, 95% CI: 0.14–0.42, p < 0.001). There was no difference in histological resolution between the two subtypes (HR: 0.70, 95% CI: 0.47–1.05, p = 0.084). Conclusion: Patients with LC have a higher chance of changing their histology as compared to CC. However, histological resolution was associated with the use of PPIs and aspirin, and treatment with budesonide.
VE303, a Defined Bacterial Consortium, for Prevention of Recurrent Clostridioides difficile Infection
Louie, Thomas , Golan, Yoav , Khanna, Sahil , Bobilev, Dmitri, Erpelding, Nathalie, Fratazzi, Candida, Carini, Meg, Menon, Rajita , Ruisi, Mary, Faith, Jeremiah J. , Olle, Bernat , Li, Minran, Silber, Jeffrey L. , Pardi, Darrell S. , Norman, Jason M.

JAMA | April 15, 2023 | Volume: 329 | Issue: 16 | Pages: 1356

10.1001/jama.2023.4314 Get It

ImportanceThe effect of rationally defined nonpathogenic, nontoxigenic, commensal strains of Clostridia on prevention of Clostridioides difficile infection (CDI) is unknown.ObjectiveTo determine the efficacy of VE303, a defined bacterial consortium of 8 strains of commensal Clostridia, in adults at high risk for CDI recurrence. The primary objective was to determine the recommended VE303 dosing for a phase 3 trial.Design, Setting, and ParticipantsPhase 2, randomized, double-blind, placebo-controlled, dose-ranging study conducted from February 2019 to September 2021 at 27 sites in the US and Canada. The study included 79 participants aged 18 years or older who were diagnosed with laboratory-confirmed CDI with 1 or more prior CDI episodes in the last 6 months and those with primary CDI at high risk for recurrence (defined as aged ≥75 years or ≥65 years with ≥1 risk factors: creatinine clearance &amp;lt;60 mL/min/1.73 m2, proton pump inhibitor use, remote [&amp;gt;6 months earlier] CDI history).InterventionsParticipants were randomly assigned to high-dose VE303 (8.0 × 109 colony-forming units [CFUs]) (n = 30), low-dose VE303 (1.6 × 109 CFUs) (n = 27), or placebo capsules (n = 22) orally once daily for 14 days.Main Outcomes and MeasuresThe primary efficacy end point was the proportion of participants with CDI recurrence at 8 weeks using a combined clinical and laboratory definition. The primary efficacy end point was analyzed in 3 prespecified analyses, using successively broader definitions for an on-study CDI recurrence: (1) diarrhea consistent with CDI plus a toxin-positive stool sample; (2) diarrhea consistent with CDI plus a toxin-positive, polymerase chain reaction–positive, or toxigenic culture–positive stool sample; and (3) diarrhea consistent with CDI plus laboratory confirmation or (in the absence of a stool sample) treatment with a CDI-targeted antibiotic.ResultsBaseline characteristics were similar across the high-dose VE303 (n = 29; 1 additional participant excluded from efficacy analysis), low-dose VE303 (n = 27), and placebo (n = 22) groups. The participants’ median age was 63.5 years (range, 24-96); 70.5% were female; and 1.3% were Asian, 1.3% Black, 2.6% Hispanic, and 96.2% White. CDI recurrence rates through week 8 (using the efficacy analysis 3 definition) were 13.8% (4/29) for high-dose VE303, 37.0% (10/27) for low-dose VE303, and 45.5% (10/22) for placebo (P = .006, high-dose VE303 vs placebo).Conclusions and RelevanceAmong adults with laboratory-confirmed CDI with 1 or more prior CDI episodes in the last 6 months and those with primary CDI at high risk for recurrence, high-dose VE303 prevented recurrent CDI compared with placebo. A larger, phase 3 study is needed to confirm these findings.Trial RegistrationClinicalTrials.gov Identifier: NCT03788434
A268 RESOLUTION RATES IN OPEN-LABEL VERSUS RANDOMIZED CONTROLLED TRIALS FOR MICROBIOTA RESTORATION FOR RECURRENT CLOSTRIDIOIDES DIFFICILE INFECTION: AN UPDATED META-ANALYSIS
Pardi, Darrell S. , Khanna, Sahil , Tariq, Raseen

Journal of the Canadian Association of Gastroenterology | March 7, 2023 | Volume: 6 | Issue: Supplement_1 | Pages: 85-85

10.1093/jcag/gwac036.268 Get It

Abstract Background Microbiota restoration is highly effective to treat recurrent Clostridioides difficile infection (CDI) in observational studies (cure rates &gt;90%) but efficacy in controlled clinical trials appears lower. Purpose We performed an updated meta-analysis to assess the efficacy of microbiota restoration for recurrent CDI in open-label registered prospective clinical trials compared to randomized controlled trials (RCTs). Method A systematic search of Embase, Web of Science and Scopus was performed up to June 2022 to identify studies of interest. Clinical trials of microbiota restoration for recurrent CDI with clinical resolution with one dose as the primary outcome were included. We calculated both unweighted and weighted pooled resolution rates (UPR and WPR) with 95% confidence intervals (CI). Result(s) Eighteen studies (9 RCTs and 9 open-label trials) with 1149 CDI patients were included. Of the patients treated with microbiota restoration, 881 experienced symptom resolution (UPR 77%%; WPR 79%, 95% CI, 72%-85%). There was significant heterogeneity among studies with an I2of 86%. Analysis of trials with a control arm (non-microbiota restoration) revealed CDI resolution in 357 of 496 patients (UPR 72%; WPR 73%, 95% CI 63%-82%) with microbiota restoration. Among the 9 open-label clinical trials, CDI resolution was seen in 524 of 653 patients after initial microbiota restoration (UPR 80%; WPR 84%, 95% CI 74%-92%). Comparison of resolution rates between RCTs and open-label trials revealed a lower cure rate in RCTs compared to open-label trials (WPR 73% vs 84%, p&lt;0.0001). Analysis of the 10 trials with non-microbiota restoration revealed CDI resolution in 201 of 397 patients with antibiotics (WPR 52%, 95% CI 43%-60%). There was significant heterogeneity among the included studies with an I2of 61%. Comparison of cure rates with microbiota restoration vs antibiotics showed higher cure rate with microbiota restoration (WPR 73%, [95% CI 63%-82%] vs 52% [95% CI, 43%-60%]; p&lt;0.0001). There were no serious adverse events reported. Conclusion(s) Microbiota restoration in a randomized controlled setting leads to lower resolution rates compared to open label and observational settings, likely due to stricter definitions and inclusion criteria. Resolution rates in open label studies were similar to observational studies. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest None Declared
Safety and Tolerability of SER-109 as an Investigational Microbiome Therapeutic in Adults With Recurrent Clostridioides difficile Infection
Sims, Matthew , Khanna, Sahil , Louie, Thomas , Kelly, Colleen , Hohmann, Elizabeth , Wang, Elaine E. L., Oneto, Caterina , Cohen, Stuart H. , Berenson, Charles S., Korman, Louis Y. , Lee, Christine , Lashner, Bret A., Kraft, Colleen S., Ramesh, Mayur , Silverman, Michael H. , Pardi, Darrell S. , Hasson, Brooke , McGovern, Barbara , Moltke, Lisa Von, Investigators, ECOSPOR IV, Hemaidan, Anmar, Kumar, Princy , Misra, Bharat , Nathan, Richard, Pullman, John, Williams, Jeffrey G., Acosta, Idalia, Odio, Alberto, Smith, Kent, Hansen, Val, Georgetson, Michael, Sheikh, Aasim , Arimie, Calin, Andrade, Gladys, O’Marro, Steven, Esfandyari, Tuba, Ritter, Timothy E., Baird, Ian Mcnicol, Colman, Ronald, Hernandez, Lilliam, Adams, Atoya, Walton, Marie, Arsenescu, Razvan, Shapiro, Max, Cook, Paul, Heuer, Marvin, Bogdanovich, Tatiana, Grimard, Doria, Butt, Debra, Gauthier, Stephanie , Guímont, Chantal, Kreines, Michael, Berman, Larry, Bennett, Michael , Fogel, Ronald, Gutierrez, Juan Carlos Moises, Pedersen, P.C. , Bressler, Adam, Nadar, Venkatesh, Newton, Eric, Abbas, Jalal, Jamal, Aamir, Benjamin, Sabrina, Ayub, Kamran, Oguchi, Godson, Pinero, Jose, Ramesh, Gowrappala, Sepe, Paul S., Brook, Loren, Ruthardt, Frederick, Surace, Lindsey, Hussain, Ayub, Rutland, Travis J., Schmalz, Micahel, Degala, Gourisankar, Phillips, Raymond E. , Stock, Kent, Bullock, Jeffrey, Onwueme, Kenolisa, Feuerstadt, Paul , Huang, Edward S. , Lee, Christine H. , Kraft, Colleen S. , Silverman, Michael, De, Ananya, Memisoglu, Asli, Lombardi, David A., Investigators, ECOSPOR IV, Nguyen, Hien , Tran, Huy, Smith, Kent, Weinstock, Leonard B. , Garcia‐Diaz, Julia , Colman, Ronald, Patel, Meenakshi, Shapiro, Max, Cook, Paul, Steiner, Theodore S. , Butt, Debra, Daley, Peter , Gauthier, Stephanie, Berman, Larry, Bennett, Michael, Pedersen, Peder, Newton, Eric, Diaz, Jorge, Abbas, Jalal, DuPont, Herbert L. , Jamal, Aamir, Talreja, Neetu, Ayub, Kamran, Phillips, Raymond

JAMA Network Open | February 13, 2023 | Volume: 6 | Issue: 2 | Pages: e2255758

10.1001/jamanetworkopen.2022.55758 Get It

ImportanceA safe and effective treatment for recurrent Clostridioides difficile infection (CDI) is urgently needed. Antibiotics kill toxin-producing bacteria but do not repair the disrupted microbiome, which promotes spore germination and infection recurrence.ObjectivesTo evaluate the safety and rate of CDI recurrence after administration of investigational microbiome therapeutic SER-109 through 24 weeks.Design, Setting, and ParticipantsThis phase 3, single-arm, open-label trial (ECOSPOR IV) was conducted at 72 US and Canadian outpatient sites from October 2017 to April 2022. Adults aged 18 years or older with recurrent CDI were enrolled in 2 cohorts: (1) rollover patients from the ECOSPOR III trial who had CDI recurrence diagnosed by toxin enzyme immunoassay (EIA) and (2) patients with at least 1 CDI recurrence (diagnosed by polymerase chain reaction [PCR] or toxin EIA), inclusive of their acute infection at study entry.InterventionsSER-109 given orally as 4 capsules daily for 3 days following symptom resolution after antibiotic treatment for CDI.Main Outcomes and MeasuresThe main outcomes were safety, measured as the rate of treatment-emergent adverse events (TEAEs) in all patients receiving any amount of SER-109, and cumulative rates of recurrent CDI (toxin-positive diarrhea requiring treatment) through week 24 in the intent-to-treat population.ResultsOf 351 patients screened, 263 were enrolled (180 [68.4%] female; mean [SD] age, 64.0 [15.7] years); 29 were in cohort 1 and 234 in cohort 2. Seventy-seven patients (29.3%) were enrolled with their first CDI recurrence. Overall, 141 patients (53.6%) had TEAEs, which were mostly mild to moderate and gastrointestinal. There were 8 deaths (3.0%) and 33 patients (12.5%) with serious TEAEs; none were considered treatment related by the investigators. Overall, 23 patients (8.7%; 95% CI, 5.6%-12.8%) had recurrent CDI at week 8 (4 of 29 [13.8%; 95% CI, 3.9%-31.7%] in cohort 1 and 19 of 234 [8.1%; 95% CI, 5.0%-12.4%] in cohort 2), and recurrent CDI rates remained low through 24 weeks (36 patients [13.7%; 95% CI, 9.8%-18.4%]). At week 8, recurrent CDI rates in patients with a first recurrence were similarly low (5 of 77 [6.5%; 95% CI, 2.1%-14.5%]) as in patients with 2 or more recurrences (18 of 186 [9.7%; 95% CI, 5.8%-14.9%]). Analyses by select baseline characteristics showed consistently low recurrent CDI rates in patients younger than 65 years vs 65 years or older (5 of 126 [4.0%; 95% CI, 1.3%-9.0%] vs 18 of 137 [13.1%; 95% CI, 8.0%-20.0%]) and patients enrolled based on positive PCR results (3 of 69 [4.3%; 95% CI, 0.9%-12.2%]) vs those with positive toxin EIA results (20 of 192 [10.4%; 95% CI, 6.5%-15.6%]).Conclusions and RelevanceIn this trial, oral SER-109 was well tolerated in a patient population with recurrent CDI and prevalent comorbidities. The rate of recurrent CDI was low regardless of the number of prior recurrences, demographics, or diagnostic approach, supporting the beneficial impact of SER-109 for patients with CDI.Trial RegistrationClinicalTrials.gov identifier: NCT03183141
Biologics: how far can they go in Crohn’s disease?
Dunleavy, Katie A. , Pardi, Darrell S. , Dunleavy, Katie

Gastroenterology Report | September 29, 2022 | Volume: 10 | Issue: No issue available | Pages: No page available

10.1093/gastro/goac049 Get It

Abstract Crohn’s disease is a chronic gastrointestinal inflammatory disorder, characterized by episodes of relapsing and remitting flares. As the disease mechanism becomes better elucidated, there is a significant increase in the number of available biologic therapies. This article summarizes and synthesizes current Food and Drug Administration-approved biological therapy for Crohn’s disease and examines the positioning of medical therapy as emerging biologics break onto the market.
Management of Acute and Chronic Pouchitis
Tome, June , Raffals, Laura E., Pardi, Darrell S. , Tome, June , Raffals, Laura E.

Diseases of the Colon & Rectum | July 31, 2022 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1097/dcr.0000000000002562 Get It

BACKGROUND: Restorative proctocolectomy with ileal pouch-anal anastomosis is the procedure of choice when colectomy is needed for medically refractory ulcerative colitis. Pouchitis is one of the most common complications among patients who have undergone ileal pouch-anal anastomosis and represents a spectrum of disease varying in both phenotype and clinical course. OBJECTIVE: The aim of this review is to assist clinicians and surgeons in the treatment of both acute and chronic pouchitis, including newer therapies and future directions. DIAGNOSIS AND MANAGEMENT: Diagnosis is made by endoscopy of the pouch with biopsy, since other conditions may produce similar symptoms such as increased stool frequency, abdominal cramps, and urgency. Pouchitis is classified by duration (acute versus chronic), disease pattern (infrequent, relapsing, continuous), and response to antibiotics (responsive, dependent, refractory). The Pouchitis Disease Activity Index may be used to measure disease activity. The management of pouchitis is guided by the disease phenotype. Acute episodes are treated with an initial 2-week course of antibiotics (typically ciprofloxacin or metronidazole), although patients with relapsing or chronic pouchitis may require long-term antibiotic treatment or the cycling of different antibiotics. Certain probiotics may also be used for maintenance therapy in those with chronic symptoms. For patients with chronic antibiotic refractory pouchitis, oral budesonide, immunosuppressive agents (azathioprine), or biologic therapy (infliximab, adalimumab, vedolizumab, ustekinumab) may be required for both induction and maintenance with close monitoring for potential side effects. In rare cases, diverting ileostomy or pouch excision may be required. CONCLUSION: Pouchitis represents a spectrum of disease phenotypes, ranging from acute antibiotic responsive pouchitis to chronic antibiotic refractory pouchitis. The management of pouchitis is primarily directed by the disease phenotype.
Microscopic colitis: Etiopathology, diagnosis, and rational management
Nielsen, Ole Haagen , Sato, Toshiro , Pardi, Darrell S. , Fernández-Bañares, Fernando

eLife | July 19, 2022 | Volume: 11 | Issue: No issue available | Pages: No page available

10.7554/elife.79397 Get It

Microscopic colitis is an inflammatory bowel disease divided into two subtypes: collagenous colitis and lymphocytic colitis. With an increasing incidence of microscopic colitis exceeding those of ulcerative and Crohn’s disease among elderly people in some countries, microscopic colitis is a debilitating life experience. Therefore, physicians should be familiar with its clinical features and management strategies because the disease deserves the same attention as the classical inflammatory bowel diseases. Here, state-of-the-art knowledge of microscopic colitis is provided from a global perspective with reference to etiopathology and how to establish the diagnosis with the overall aim to create awareness and improve rational management in clinical practice. The immune system and a dysregulated immune response seem to play a key role combined with risk factors (e.g. cigarette smoking) in genetically predisposed individuals. The symptoms are characterized by recurrent or chronic nonbloody, watery diarrhea, urgency, weight loss, and a female preponderance. As biomarkers are absent, the diagnosis relies on colonoscopy with a histological assessment of biopsy specimens from all parts of the colon. Although the disease is not associated with a risk of colorectal cancer, a recent nationwide, population-based cohort study found an increased risk of lymphoma and lung cancer. Budesonide is the first-line therapy for management, whereas immunomodulatory drugs (including biologics) and drugs with antidiarrheal properties may be indicated in those failing, dependent, or intolerant to budesonide. In microscopic colitis induced by checkpoint inhibitors, a drug class used increasingly for a wide range of malignancies, a more aggressive therapeutic approach with biologics introduced early seems reasonable. However, particular attention needs to be drawn to the existence of incomplete forms of microscopic colitis with the risk of being overlooked in routine clinical settings.
Budesonide Maintenance in Microscopic Colitis: Clinical Outcomes and Safety Profile From a Population-Based Study
Tome, June , Sehgal, Kanika , Kamboj, Amrit K. , Comstock, Bryce, W, Scott Harmsen, Khanna, Sahil , Pardi, Darrell S. , Tome, June

American Journal of Gastroenterology | April 13, 2022 | Volume: 117 | Issue: 8 | Pages: 1311-1315

10.14309/ajg.0000000000001774 Get It

INTRODUCTION: Outcomes and safety of budesonide maintenance therapy in microscopic colitis (MC) are not well known. METHODS: Adult residents of Olmsted County, Minnesota, diagnosed with MC (2002–2019) and treated with budesonide were identified using the Rochester Epidemiology Project. Response was assessed at 12 ± 4 weeks after initiation of therapy and defined as complete (resolution of diarrhea), partial (≥50% improvement in the number of bowel movements), nonresponse (<50% improvement), and intolerance (discontinued because of side effects). For safety outcomes, cases (budesonide maintenance) and MC controls (no budesonide therapy) were matched by sex and age at diagnosis (±2 years). RESULTS: A total of 450 patients were identified, of whom 162 (36.0%) were treated with budesonide for induction of clinical remission (median age 67 [23–91] years and 126 women [77.8%] ). Clinical outcomes for induction were as follows: 130 (80.2%) complete response, 22 (13.6%) partial response, 8 (4.9%) no response, and 2 (1.2%) intolerance. After induction, 96 (63.2%) had recurrence after discontinuation, of whom 27 (28.1%) required further budesonide induction treatment without maintenance, 56 (58.3%) required long-term budesonide maintenance, and 13 (13.5%) were treated with other therapies. Of those receiving budesonide maintenance, all responded (55 [98.2%] complete and 1 [1.8%] partial). No patient stopped maintenance from adverse events. The median duration of follow-up was 5.6 years (0.3–18.9). There was no significant difference between cases and controls in the incidence of osteopenia/osteoporosis, diabetes mellitus, hypertension, glaucoma, or cataracts. DISCUSSION: The long-term use of budesonide in MC seems to be effective and generally well tolerated with limited adverse effects.
Clinical Course and Impact of Immune Checkpoint Inhibitor Colitis Resembling Microscopic Colitis
Fredrick, Thomas , Ramos, Guilherme Piovezani , Neto, Manuel B. Braga , Kane, Sunanda V. , Faubion, William A. , Loftus, Edward V. , Pardi, Darrell S. , Pasha, Shabana F., Farraye, Francis A. , Zhang, Lizhi , Raffals, Laura E. , Fredrick, Thomas W , Ramos, Guilherme P , Braga Neto, Manuel B , Kane, S , Loftus, Edward V , Farraye, Francis A

Crohn's & Colitis 360 | March 14, 2022 | Volume: 4 | Issue: 2 | Pages: No page available

10.1093/crocol/otac008 Get It

Abstract Background Microscopic colitis (MC) is suspected to result from increased immune activity in gut mucosa. Immune checkpoint inhibitors (ICIs) treat cancer by activating the immune system, and further investigation is needed regarding their role in the development of MC. Methods A retrospective case series investigated cases of endoscopically and histologically confirmed MC developing after administration of ICIs. Clinical notes and medication administration records were reviewed for demographics, symptom duration, and treatment response. Results Nineteen cases of de novo MC were identified, with 95% of cases requiring steroid treatment, 53% presenting with hospitalization, and colitis-related mortality in 1 individual. Symptom onset occurred a median of 160 days after initiation of ICI therapy and 53 days after their most recent dose of therapy. Patients had a median of 125 days of symptoms, and ICI therapy was held in 70% of individuals due for treatment. Conclusions MC can develop after ICI administration, and presents with severe symptoms, often requiring hospitalization and steroid treatment. In certain individuals this can require a prolonged treatment course of steroid therapy or immunomodulators. Individuals developing diarrhea after ICI therapy warrant thorough workup including endoscopy and rapid treatment initiation given the disease severity observed in this series.