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Grade 3 Immune-Mediated Colitis on Nivolumab plus Ipilimumab

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Grade 3 Immune-Mediated Colitis on Nivolumab plus Ipilimumab

A 58-year-old woman with unresectable BRAF wild-type stage IV melanoma is receiving nivolumab 1 mg/kg plus ipilimumab 3 mg/kg every 3 weeks; today is day 12 after her second dose. She reports 8 watery stools per day above baseline for 3 days, with urgency and cramping. She is afebrile, normotensive, with a soft abdomen and no peritoneal signs. Stool cultures, C. difficile testing, and CMV PCR are negative; CT shows diffuse colonic wall thickening without perforation or abscess. Labs: sodium 132 mmol/L, potassium 3.2 mmol/L, creatinine 1.3 mg/dL (baseline 0.8), albumin 3.1 g/dL. Her grade 1 pruritus from cycle 1 has resolved and she has no other immune-related toxicities. She takes no anticoagulants and has no history of inflammatory bowel disease.

1. Grade the event and write your immediate pharmacologic plan for the first 72 hours.

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Grade 3 immune-mediated colitis (>=7 stools/day above baseline, with radiographically confirmed colitis, no fever, no perforation).

First 72 hours:

  1. Hold both nivolumab and ipilimumab immediately.
  2. Admit for IV isotonic fluids and electrolyte replacement (K 3.2, Na 132); pre-renal azotemia is present (creatinine 1.3 from 0.8).
  3. High-dose systemic corticosteroids today, not tomorrow: methylprednisolone 1 mg/kg/day IV (or prednisone 1-2 mg/kg/day PO if tolerating). Do not wait for endoscopy in a clear-cut case.
  4. No antimotility agents (loperamide, atropine/diphenoxylate) - risk of ileus, toxic megacolon, perforation.
  5. Daily reassessment: stool count, abdominal exam, CRP, CMP, CBC; repeat stool studies only if the picture changes. Consider flexible sigmoidoscopy if the diagnosis is in doubt or steroids are failing.
  6. Continue supportive care: VTE prophylaxis per hospital protocol, PPI for stress ulcer risk (she is not otherwise on one), and dexamethasone-free antiemetics.

Do not stop steroids early. Anticipate a taper measured in weeks; a 3-day course followed by abrupt discontinuation is a classic cause of rebound colitis.

2. The patient is only modestly better at 48 hours (6 stools/day, still cramping). Outline your escalation strategy, including when you would give infliximab or an alternative biologic and what screening is required.

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Escalate at 48-72 hours if not clearly improving on high-dose steroids - persistent >=4-6 stools/day, worsening pain, or rising CRP all qualify.

First-line escalation: infliximab 5 mg/kg IV single dose.

  • Screen for HBV (HBsAg, anti-HBc total, anti-HBs) and latent TB (IGRA) and chest imaging - but do not delay the dose in severe, steroid-refractory colitis; positive HBV serologies call for antiviral prophylaxis (e.g., entecavir), not necessarily withholding infliximab.
  • If partial response, repeat infliximab 5 mg/kg at 2 weeks. If no response to the first dose, do not simply repeat endlessly.
  • Counsel about infusion reaction, delayed hypersensitivity, and infection risk.

If infliximab fails or is contraindicated: vedolizumab 300 mg IV (gut-selective, less systemic immunosuppression) is a reasonable second biologic; some centers use it earlier in patients with significant infection risk.

Do not use: mycophenolate mofetil, tacrolimus as routine first escalation, or TNF inhibitors in a patient with perforation/sepsis. Surgical consultation early if abdominal pain worsens, if the abdomen becomes rigid, or if the patient develops fever with rising white count - perforation is the lethal complication.

Reassess steroid dose (2 mg/kg/day methylprednisolone can be used for refractory disease) and nutrition; TPN is rarely needed but consider it if ileus develops.

3. State the rechallenge rules for each immunotherapy drug, the steroid taper, and the prophylaxis the patient will need during the taper.

Read the worked answer

Ipilimumab: permanently discontinued. Grade 3 immune-mediated colitis precludes any further ipilimumab (verify against your current package insert and protocol).

Nivolumab: withheld, potentially resumable. May restart single-agent nivolumab once colitis resolves to grade <=1 and the steroid has been tapered to a low dose (commonly <=10 mg/day prednisone equivalent). It would be permanently discontinued for grade 4 colitis or a recurrent grade 3 event on rechallenge.

Taper: reduce slowly over at least 4 weeks (often 6-8 weeks after a long high-dose course), e.g., drop by 5-10 mg prednisone equivalent every 5-7 days once symptoms resolve. Tapering faster is the leading cause of recurrent colitis. Monitor stools and CRP at each step.

Prophylaxis and supportive care during the steroid course:

  • PJP prophylaxis (TMP-SMX DS daily or three times weekly) if prednisone >=20 mg/day for >=4 weeks; alternatives for sulfa allergy: dapsone (check G6PD), atovaquone, inhaled pentamidine.
  • Bone health: calcium + vitamin D, consider bisphosphonate if the course is prolonged; glucose monitoring (steroid-induced hyperglycemia).
  • GI follow-up, and explicit return precautions: recurrence of diarrhea, blood in stool, fever, or inability to taper.
  • Document the irAE in the survivorship/immunotherapy record so future providers do not re-expose her to ipilimumab.