P2642 - The When, the Where, and the How: Temporal and Quantitative Trends in Fecal Calprotectin Levels and the Implications for Checkpoint-Inhibitor Colitis

Malek Satila, MD¹, Linfeng Lu, MD², Tanvi Gupta, MD³, Andres Rivera, MD², Kian Abdul-Baki, DO⁴, Elliot Axel. Baerman, MD², Hamza Salim, MD⁴, Kei Takigawa, MD², Andrew Sullivan, MD⁵, Irene J. Lee, MD², Carolina Colli Cruz, MD¹, Raakhi Menon, DO⁴, Varun Vemulapalli, MD³, Cristina M. Natha, MD³, Ayesha Khan, DO⁴, Garrett T. Coleman, ⁶, Krishnavathana Varatharajalu, MD⁷, Anusha Thomas, MD⁷, Yinghong Wang, MD, PhD^8
1MD Anderson Cancer Center, Houston, TX; ²Baylor College of Medicine, Houston, TX; ³University of Texas Health, McGovern Medical School, Houston, TX; ⁴University of Texas Medical Branch, Galveston, TX; ⁵University of Texas Health Science Center, 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 colitis (IMC) is a common toxicity secondary to immune-checkpoint inhibition (ICI) that can interfere with cancer treatment. There is a massive gap in the literature on how to monitor this disease. Fecal calprotectin (FC) has been useful in the initial evaluation and surveillance of this toxicity. However, there is no information on the interval of FC testing and the dynamics of FC values over time for this disease entity and how they impact clinical outcomes. We present the first study to explore the dynamics of FC monitoring for IMC.

Methods: This was a single center, retrospective review including all patients who received ICIs between 01/2010 to 02/2024, developed IMC, and had FC levels available at the time of diagnosis. We collected data on patient demographic information and colitis clinical information including presentation, endoscopic features, treatments, and outcomes. SPSS 26.0 was used to analyze the data.

Results: 802 patients met the study criteria. Elevated baseline FC was associated with a higher grade of diarrhea, hospitalization and re-hospitalization for colitis, and ulcers on endoscopy (p< 0.05 for all). Normalization of FC levels was significantly associated with symptom remission (p< 0.05) and occurred in a median of 4.1 months (IQR: 2.4-6.9). As low as a 25% decrease from baseline FC was associated with clinical remission (p< 0.05), with a 75% decrease showing a higher trend in the rate of endoscopic remission (60.8% vs. 41.9% of those without a 75% decrease; p=0.069). FC dropped by 72.9% from an initially elevated baseline within a median of 2.2 months (IQR: 1.3-3.5). The time taken for FC to improve by 25% or 75% was associated with symptom resolution (p< 0.05). Finally, normalization of FC was associated with improved overall survival (OR: 0.5, CI: 0.3-0.8; p=0.028) among patients with colitis.

Discussion: This is the largest study to date reporting the quantitative and temporal changes in fecal calprotectin levels among patients with IMC. We found that baseline FC is a useful prognostic marker for future disease course. Normalization of FC and improvement in elevated baseline levels of at least 25% were associated with clinical remission, and typically occur at around 4 and 2 months respectively. These results support the utility of obtaining baseline calprotectin levels and re-checking them at 2-3 months after disease onset.


Disclosures:


Malek Satila, MD¹, Linfeng Lu, MD², Tanvi Gupta, MD³, Andres Rivera, MD², Kian Abdul-Baki, DO⁴, Elliot Axel. Baerman, MD², Hamza Salim, MD⁴, Kei Takigawa, MD², Andrew Sullivan, MD⁵, Irene J. Lee, MD², Carolina Colli Cruz, MD¹, Raakhi Menon, DO⁴, Varun Vemulapalli, MD³, Cristina M. Natha, MD³, Ayesha Khan, DO⁴, Garrett T. Coleman, ⁶, Krishnavathana Varatharajalu, MD⁷, Anusha Thomas, MD⁷, Yinghong Wang, MD, PhD⁸. P2642 - The When, the Where, and the How: Temporal and Quantitative Trends in Fecal Calprotectin Levels and the Implications for Checkpoint-Inhibitor Colitis, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.