P4340 - Mystery Diarrhea: A Comparative Analysis of Immune-Mediated Colitis Disease Characteristics Among Patients With and Without Signs of Inflammation on Initial Work-Up

Malek Satila, MD¹, Carolina Colli Cruz, MD¹, Andres Rivera, MD², Andrew Sullivan, MD³, Kian Abdul-Baki, DO⁴, Irene J. Lee, MD², Kei Takigawa, MD², Elliot Axel. Baerman, MD², Linfeng Lu, MD², Hamza Salim, MD⁴, Raakhi Menon, DO⁴, Varun Vemulapalli, MD⁵, Cristina M. Natha, MD⁵, Tanvi Gupta, MD⁵, Ayesha Khan, DO⁴, Garrett T. Coleman, ⁶, Krishnavathana Varatharajalu, MD⁷, Yinghong Wang, MD, PhD^8
1MD Anderson Cancer Center, Houston, TX; ²Baylor College of Medicine, Houston, TX; ³University of Texas Health Science Center, Houston, TX; ⁴University of Texas Medical Branch, Galveston, TX; ⁵University of Texas Health, McGovern Medical School, Houston, TX; ⁶University of Texas Medical Branch, John Sealy School of Medicine, Galveston, TX; ⁷The University of Texas MD Anderson Cancer Center, Houston, TX; ⁸University of Texas MD Anderson Cancer Center, Houston, TX

Introduction: Immune-mediated diarrhea and/or colitis (IMDC) is an adverse effect of immune checkpoint inhibition (ICI) that frequently necessitates treatment discontinuation. Stool biomarkers such as lactoferrin and calprotectin and endoscopic findings are instrumental in arriving at the diagnosis but may all be normal. To date, there is no literature describing these cases of IMDC with diarrhea but normal stool inflammatory work up. Our study aims to present a descriptive comparison of IMDC with and without evidence of colonic inflammation.

Methods: This was a single center, retrospective review including all patients who received ICI between 01/2010 to 2/2024 and developed IMDC after exclusion of alternative etiologies. Patients were screened for IMDC based on stool tests, then divided into two groups depending on the results of stool tests and/or endoscopy findings (normal group – NG; abnormal group AG) at colitis onset. Patients with no such evaluation of either at baseline were excluded. We collected data on patient demographics and colitis clinical information.

Results: 1,068 patients met the study criteria and were included, 93 (4.7%) of whom were in the NG. Patients with normal initial work-up developed IMDC in a median of 3.6 months (IQR: 1.3-9.6) from ICI initiation compared to 3.3 (1.4-8.6) months among the AG. Patients in the NG had lower rates of grade 2 or above diarrhea (71.1% vs. 82.1% in the AG; p< 0.05) and were less likely to require treatment with steroids, selective immunosuppressive therapy, and FMT (p< 0.05 for all). Patients in the NG also had lower hospitalization rates (41.8% vs. 63.5% in the AG). Finally, patients in both groups had comparable rates of symptom remission (85.1% in the NG vs. 84.3% in the AG; p=1.000).

Discussion: Our study is the first to describe the disease characteristics of IMDC with negative evidence of intestinal inflammation compared to those with typical signs of inflammation on stool biomarker or endoscopic evaluation. We found that this subgroup often presents at a lower severity than patients with signs of inflammation on initial work-up and is less likely to require aggressive treatment. Future studies are needed with a larger subgroup to derive more meaningful conclusions.


Disclosures:


Malek Satila, MD¹, Carolina Colli Cruz, MD¹, Andres Rivera, MD², Andrew Sullivan, MD³, Kian Abdul-Baki, DO⁴, Irene J. Lee, MD², Kei Takigawa, MD², Elliot Axel. Baerman, MD², Linfeng Lu, MD², Hamza Salim, MD⁴, Raakhi Menon, DO⁴, Varun Vemulapalli, MD⁵, Cristina M. Natha, MD⁵, Tanvi Gupta, MD⁵, Ayesha Khan, DO⁴, Garrett T. Coleman, ⁶, Krishnavathana Varatharajalu, MD⁷, Yinghong Wang, MD, PhD⁸. P4340 - Mystery Diarrhea: A Comparative Analysis of Immune-Mediated Colitis Disease Characteristics Among Patients With and Without Signs of Inflammation on Initial Work-Up, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.