P2254 - Complicated Diverticulitis After Immune Checkpoint Inhibitor Therapy

Award: Presidential Poster Award

Award: Presidential Poster Award

Austin R. Thomas, DO, MA, Yinghong Wang, MD, PhD, MS
University of Texas MD Anderson Cancer Center, Houston, TX

Introduction: Immune checkpoint inhibitors (ICIs) are an efficacious treatment for many malignancies but unfortunately can cause severe immune related adverse events (irAEs), often affecting the gastrointestinal (GI) tract. Though rare, there is growing evidence that ICIs might induce diverticulitis. Here, we present three patients who had complicated diverticulitis after ICI with fistula/abscess formation that required additional medical and surgical management.

Case Description/Methods: All three patients included in this case series had stage IV cancer and received ICIs. Patient A was a female with tongue cancer who developed abdominal pain and diarrhea 13 months after starting pembrolizumab. Imaging revealed diverticulitis associated with a colovaginal fistula. She received antibiotics, corticosteroids, vedolizumab, and ultimately required ustekinumab for her co-existing ICI colitis confirmed on colonoscopy/histology. Ustekinumab offered moderate relief of symptoms. Colonoscopy shortly after first ustekinumab dose revealed mild colitis. Surprisingly, this patient never developed clinical symptoms of colovaginal fistula. Patient B was a male with melanoma who developed abdominal pain, fever, and pneumaturia 8 months after beginning nivolumab/ipilimumab. Acute diverticulitis and a colovesical fistula were seen on CT, and subsequently treated with prolonged antibiotics. His abdominal pain and pneumaturia persisted, however. Colonoscopy with biopsy did not reveal any inflammation. Patient C had melanoma and developed abdominal pain and diarrhea one month after starting nivolumab/ipilimumab. Imaging showed diverticulitis associated with abscess for which he underwent drainage by interventional radiology (IR) and received antibiotics. He also required corticosteroids and vedolizumab for accompanying ICI colitis, and did not have recurrent abscesses or diarrhea.

Discussion: GI related irAEs from ICI are common and can have presentations across the spectrum. Co-existing colitis and diverticulitis can occur and may be associated with fistula and abscess formation. Early recognition and proper management for these complications is critical to ensure best outcome.

	Patient A	Patient B	Patient C
Age at diagnosis of fistula / abscess	74	62	57
Gender	Female	Male	Male
Primary cancer	Squamous cell carcinoma of tongue	Melanoma of upper back	Melanoma of nose
ICI	Pembrolizumab	Ipilimumab, nivolumab	Ipilimumab, nivolumab
Symptoms	Diarrhea	Abdominal pain, fever, pneumaturia	Abdominal pain, diarrhea
Time to symptom onset after ICI	13 months	8 months	1 month
Diverticulitis complications	Colovaginal fistula	Colovesical fistula	Diverticular abscess
Pertinent CT findings	Fistulous tract between sigmoid colon and vaginal cuff, containing small air foci and fluid	Acute diverticulitis, diverticulum with channel to bladder, large amount of gas in bladder	Sigmoid colon diverticulitis with contained abscess, distal small bowel and colonic mucosal enhancement
Colonoscopy	Diverticulosis, congested and erythematous mucosa from rectum to sigmoid, granularity in distal rectum	Diverticulosis	Diverticulosis, 3 diverticuli with erythema
Treatment of diverticulitis complications	Antibiotics	Antibiotics	Antibiotics, abscess drainage by IR
Treatment of GI irAEs	Corticosteroids, vedolizumab, ustekinumab	None	Corticosteroids, vedolizumab
Cancer status at last follow up	Stable	Stable	Stable
Vital status	Living	Living	Living

Disclosures:
Austin Thomas indicated no relevant financial relationships.
Yinghong Wang: AzurRx Pharma – Consultant. Tillotts Pharma – Consultant.


Austin R. Thomas, DO, MA, Yinghong Wang, MD, PhD, MS. P2254 - Complicated Diverticulitis After Immune Checkpoint Inhibitor Therapy, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.