Nivolumab and Ipilimumab - Side Effects

Note on spelling: You likely mean nivolumab (Opdivo) and ipilimumab (Yervoy). These are two immune checkpoint inhibitors commonly used together or as monotherapy in cancers such as melanoma, NSCLC, and renal cell carcinoma.

Mechanisms (Why They Cause These Effects)

• Nivolumab blocks PD-1 (programmed cell death protein 1), an inhibitory receptor on T cells - releasing the "brake" on T cell activity against tumors.
• Ipilimumab blocks CTLA-4, a different inhibitory receptor that competes with CD28 to downregulate early T cell activation.

Side Effects by System

Dermatological (Most Common)

Gastrointestinal

• Colitis - one of the most significant irAEs, especially with ipilimumab
• Diarrhea, enterocolitis (can be severe; may require fluid/electrolyte repletion)
• Immune-mediated hepatitis (elevated transaminases; also seen with nivolumab)

Endocrine

• Thyroiditis (hypo- or hyperthyroidism)
• Hypophysitis (pituitary inflammation - can cause panhypopituitarism, very characteristic of ipilimumab)
• Adrenal insufficiency (can be life-threatening if missed)

Pulmonary

• Pneumonitis - can require oxygen therapy or mechanical ventilation in severe cases

Cardiac

• Myocarditis - rare but potentially fatal; presents with new dyspnea, arrhythmias, or pulmonary edema

Neurological

• Neuropathy, encephalopathy, cranial nerve palsies
• Recent systematic review (2024) documented cranial nerve involvement in 136 patients on checkpoint inhibitors

Renal

• Nephritis (interstitial nephritis most common)

Nivolumab vs. Ipilimumab: Comparative Toxicity

Onset and Timing

Management of irAEs

1. Mild (Grade 1): Continue therapy with monitoring
2. Moderate-Severe (Grade 2-3): Interrupt checkpoint inhibitor; start systemic corticosteroids (mainstay of treatment)
3. Refractory / Grade 4: Add TNF-alpha antagonists (e.g., infliximab for colitis); discontinue drug
4. ICU-level irAEs: Severe pneumonitis (ventilatory support), myocarditis (inotropes, antiarrhythmics), hepatic failure, severe enterocolitis (IV fluids/electrolytes)
5. Opportunistic infections are a real risk in patients on prolonged immunosuppression for irAE management

Key Takeaways

• irAEs can affect virtually any organ - think "immune attack on self"
• Ipilimumab (CTLA-4) generally causes more severe toxicity than nivolumab (PD-1)
• Combining both dramatically raises efficacy AND toxicity
• Paradoxically, some irAEs (especially vitiligo/leukoderma) correlate with better treatment response
• Management is primarily immunosuppression with corticosteroids

Endocrine Side Effects: When Do They Start?

General Timeline of All irAEs (for Context)

Endocrine irAEs: Specific Onset Timing

1. Thyroiditis (Hypothyroidism / Transient Thyrotoxicosis)

2. Hypophysitis (Pituitary Inflammation)

• Ipilimumab-induced hypophysitis is far more common and earlier than PD-1-induced hypophysitis
• It causes secondary adrenal insufficiency, central hypothyroidism, and hypogonadism
• Symptoms are often non-specific (headache, fatigue, visual changes) - frequently missed until adrenal crisis

3. Adrenal Insufficiency

• Mostly occurs secondary to hypophysitis (not primary adrenal failure)
• Onset mirrors hypophysitis timing: ~9-12 weeks with ipilimumab, later with PD-1 inhibitors
• Underdiagnosed - most cases only identified after symptom onset or acute crisis in emergency settings. Routine ACTH/cortisol screening is rarely performed despite guidelines recommending it.
• Life-threatening if missed; requires hydrocortisone replacement

4. ICI-Induced Diabetes Mellitus (Fulminant Type 1-like)

• Less common, more associated with PD-1 inhibitors (nivolumab, pembrolizumab)
• Can occur any time, often weeks to months into therapy
• Presents rapidly (sometimes as DKA) - faster than classic autoimmune T1DM
• Median time to onset: 1.4-4.9 months with PD-1 inhibitors

5. Overall Endocrine irAE Summary Timing

• NIH/Endotext review source

Why Endocrine Effects Appear Later

1. CTLA-4 is expressed on pituitary cells - ipilimumab creates a direct pituitary-targeted immune attack
2. PD-L1 is expressed on thyroid, pituitary, and pancreas - PD-1 blockers can attack these over time
3. Endocrine organs tolerate partial immune damage longer before becoming symptomatic (silent until >50% gland function is lost for some)
4. Immune activation is a gradual process - cumulative drug doses drive later toxicities

Clinical Bottom Line

• Thyroid: can start as early as 2 weeks (combo therapy) to 6 weeks (monotherapy) - monitor TSH/FT4 at each cycle
• Pituitary/Adrenal: typically 9-12 weeks with ipilimumab; up to 6 months with PD-1 alone - check morning cortisol + ACTH periodically
• Diabetes: weeks to months - check fasting glucose/HbA1c regularly, especially with PD-1 agents
• Endocrine irAEs can be permanent (especially hypothyroidism, adrenal insufficiency, diabetes) even after stopping the drug - unlike dermatologic/GI irAEs which often resolve
• Any patient on these drugs presenting with fatigue, headache, nausea, or weight change should prompt endocrine screening