e14585 Background: Radiologic findings associated with biopsy proven immune checkpoint inhibitor (ICI) related nephritis have not been described. The objective of this study is to describe the radiologic features of immunotherapy related nephritis on computerized tomography (CT) and positron emission tomography (PET). A secondary objective is to investigate the association of these radiologic features with renal outcomes. Methods: A retrospective review of all biopsy proven ICI-related nephritis between February 2017 and April 2021 was performed and 34 patients were identified. CT and PET-CT scans before the initiation of immune checkpoint inhibitors (baseline), at nephritis and after resolution of nephritis were reviewed. Total kidney volume, renal parenchymal SUVmax, renal pelvis SUVmax and blood pool SUVmean were obtained. Results: The total kidney volume was significantly higher at nephritis compared to baseline (464.7±96.8 mL vs. 371.7±187.7 mL; p < 0.001). Fifteen patients (44.1%) had > 30% increase in total kidney volume at nephritis. A > 30% increase in total kidney volume was associated with significantly higher renal toxicity grade (p = 0.007), higher peak creatinine level (p = 0.004) and more aggressive medical treatment (p = 0.011). New/increasing perinephric fat stranding was noted in 10 patients (29.4%) at nephritis. Among 8 patients with contrast-enhanced CT at nephritis, 1 patient (12.5%) developed bilateral wedge-shaped hypoenhancing cortical lesions that healed with focal scarring on subsequent scans. On PET-CT, the renal parenchymal SUVmax-to-blood pool SUVmean ratio was significantly higher at nephritis compared to baseline (2.13 vs. 1.68; p = 0.035). The renal pelvis SUVmax-to-blood pool SUVmean ratio was significantly lower at nephritis compered to baseline (3.47 vs. 8.22; p = 0.011). Conclusions: Bilateral increase in kidney size, new/increasing perinephric stranding and bilateral wedge-shaped hypoenhancing cortical lesions can occur in immunotherapy-related nephritis. On PET-CT, diffuse bilateral increase in radiotracer uptake throughout the renal cortex and decrease in radiotracer activity in the renal pelvis can be seen. A > 30% increase in total kidney volume was associated with significantly higher renal toxicity grade and more aggressive medical treatment in a subset of patients. Acknowledgment: National Institute of Health K01 Award (N.A.: K01AI163412).
Obesity defined by high body mass index (BMI) has traditionally been associated with gastrointestinal inflammatory processes but has recently been correlated with better survival in patients receiving immune checkpoint inhibitors (ICI). We sought to investigate the association between BMI and immune-mediated diarrhea and colitis (IMDC) outcomes and whether BMI reflects body fat content on abdominal imaging. This retrospective, single-center study included cancer patients with ICI exposure who developed IMDC and had BMI and abdominal computed tomography (CT) obtained within 30 days before initiating ICI from April 2011 to December 2019. BMI was categorized as <25, ≥25 but <30, and ≥30. Visceral fat area (VFA), subcutaneous fat area (SFA), total fat area (TFA: VFA+SFA), and visceral to subcutaneous fat (V/S) ratio were obtained from CT at the umbilical level. Our sample comprised 202 patients; 127 patients (62.9%) received CTLA-4 monotherapy or a combination, and 75 (37.1%) received PD-1/PD-L1 monotherapy. Higher BMIs ≥ 30 were associated with a higher incidence of IMDC than BMIs ≤ 25 (11.4% vs. 7.9%, respectively; p = 0.029). Higher grades of colitis (grade 3–4) correlated with lower BMI (p = 0.03). BMI level was not associated with other IMDC characteristics or did not influence overall survival (p = 0.83). BMI is strongly correlated with VFA, SFA, and TFA (p < 0.0001). Higher BMI at ICI initiation was linked to a higher incidence of IMDC but did not appear to affect outcomes. BMI strongly correlated with body fat parameters measured by abdominal imaging, suggesting its reliability as an obesity index.
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