A 54-year-old woman is evaluated in the hospital on day 3 of admission for severe fatigue,… — USMLE Step 3

A $54$ -year-old woman is evaluated in the hospital on day 3 of admission for severe fatigue, jaundice, and right upper quadrant discomfort. She has a history of metastatic melanoma and received her third cycle of ipilimumab and nivolumab three weeks prior to admission.

On admission, her viral hepatitis panel and autoimmune markers (antinuclear antibody, anti-smooth muscle antibody) were negative. A right upper quadrant ultrasound showed normal liver echotexture with no biliary dilation and normal flow in the portal and hepatic veins. She was diagnosed with Grade 3 immune-checkpoint inhibitor-induced hepatitis. Immunotherapy was permanently discontinued, and intravenous methylprednisolone $2\text{ mg/kg/day}$ was initiated.

Currently, 72 hours later, the patient reports no improvement in her symptoms. Her vital signs are temperature $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), pulse $88/\text{min}$ , and blood pressure $118/74\text{ mmHg}$ .

Serial laboratory values are shown below:

Laboratory Test	Admission	Current (72 hours later)	Reference Range
Alanine aminotransferase (ALT)	$950\text{ U/L}$	$1450\text{ U/L}$	$7-56\text{ U/L}$
Aspartate aminotransferase (AST)	$820\text{ U/L}$	$1320\text{ U/L}$	$8-48\text{ U/L}$
Total bilirubin	$2.8\text{ mg/dL}$	$3.4\text{ mg/dL}$	$0.1-1.2\text{ mg/dL}$
Alkaline phosphatase	$150\text{ U/L}$	$160\text{ U/L}$	$44-147\text{ U/L}$
INR	$1.1$	$1.4$	$0.8-1.2$

Which of the following is the most appropriate next step in the management of this patient?

Initiate mycophenolate mofetilAnswer
B
Initiate infliximab
C
Perform a percutaneous liver biopsy
D
Order magnetic resonance cholangiopancreatography
E
Initiate ursodeoxycholic acid

Answer

The most appropriate next step is to initiate mycophenolate mofetil.

This patient is experiencing Grade 3 immune-checkpoint inhibitor-induced hepatitis (ALT/AST

> 5 \times

the upper limit of normal) that is refractory to initial treatment. The standard initial management for severe immune-related adverse events (irAEs) is to permanently discontinue the offending agent(s) and start high-dose corticosteroids (e.g., methylprednisolone

1-2\text{ mg/kg/day}

). Steroid refractoriness in irAE hepatitis is typically defined as a failure of liver enzymes to improve after 3 days (72 hours) of high-dose corticosteroid therapy. In such cases, the next appropriate step in monitoring and treatment evaluation is the prompt initiation of a second-line immunosuppressive agent to prevent fulminant hepatic failure. The preferred agent for steroid-refractory irAE hepatitis is mycophenolate mofetil (MMF).

Step-by-Step Solution

Evaluate the clinical trajectory and response to initial therapy.

The patient's transaminases and bilirubin have continued to rise significantly despite 72 hours of high-dose intravenous methylprednisolone (

2\text{ mg/kg/day}

Failure to improve after 3 days of high-dose corticosteroids defines steroid-refractory immune-related adverse events, necessitating treatment escalation.

Select the appropriate second-line pharmacologic agent for the specific organ toxicity.

Mycophenolate mofetil is indicated.

Guidelines specifically recommend mycophenolate mofetil for steroid-refractory immune-related hepatitis, whereas infliximab (used in colitis) must be avoided due to inherent hepatotoxicity risks.

Key Concept

Steroid-refractory immune-checkpoint inhibitor-induced hepatitis requires escalation to mycophenolate mofetil, and infliximab is strictly contraindicated due to hepatotoxicity.

Estimated Time:1m 30s

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