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Nephrology Education Series

Student Handout: Immune Checkpoint Inhibitor Nephrotoxicity

Andrew Bland, MD, FACP, FAAP UICOMP · UDPA · Butler COM 2026-02-28 6 min read

Student Handout: Immune Checkpoint Inhibitor Nephrotoxicity

Learning objective: Understand the epidemiology, pathophysiology, clinical presentation, and management approach to immunotherapy-related kidney injury

What Are ICIs?

Immune checkpoint inhibitors are a revolutionary class of immunotherapy drugs used across many cancer types:

Drug Target Examples
Anti-PD-1 Programmed death receptor 1 Nivolumab, pembrolizumab
Anti-PD-L1 PD-1 ligand Atezolizumab, durvalumab
Anti-CTLA-4 Cytotoxic T-lymphocyte antigen 4 Ipilimumab

Key concept: These drugs release immune brakes, activating T cells to attack cancer—but sometimes attack the kidneys too.

Epidemiology

  • Frequency: 1–3% of ICI-treated patients develop clinical nephrotoxicity
  • Severity: Most Grade 1–2 (mild), but Grade 3–4 (severe) requires discontinuation
  • Timing: Usually occurs within 3–6 months, but can appear later
  • Risk factors: Baseline CKD, diabetes, prior nephrotoxic drugs, combination therapy (ICI + CTLA-4 higher risk)

Pathophysiology: How ICIs Injure the Kidney

The mechanism (simplified for PA level):

  1. Checkpoint release — Anti-PD-1/PD-L1 or anti-CTLA-4 blocks inhibitory signals
  2. T-cell activation — T cells hyperactivate against cancer antigens
  3. Cross-reactivity — T cells recognize epitopes in kidney tubules and glomeruli
  4. Inflammation — Predominantly acute interstitial nephritis (AIN), less commonly glomerular disease
  5. Result: Tubular damage → ↑ creatinine, proteinuria, microscopic hematuria

Why AIN? Mechanism mirrors classic drug-induced AIN, but driven by immune activation rather than direct toxin.

Clinical Presentation & Diagnosis

Typical Picture

  • Asymptomatic ↑ creatinine (40–90% of cases)
  • Baseline: Usually occurs 3–6 months post-initiation
  • Labs:
    • ↑ Serum creatinine (often 1.5–3× baseline)
    • ↑ BUN
    • Proteinuria (usually <2 g/day unless glomerular)
    • Microscopic or gross hematuria possible
    • Sterile pyuria (hallmark)
    • ↓ Complement (usually normal)

Diagnostic Approach

Step Action Finding
1. Suspect ICI nephrotoxicity Timeline (Cr ↑ during/after ICI) Clinical probability high
2. Check urine Urinalysis, urine Pt-Cr ratio AIN: sterile pyuria, granular casts, muddy casts
3. Check labs BMP, LDH, phosphate, uric acid Normal complement distinguishes from GN
4. Assess volume Physical exam, I/Os Usually euvolemic or hypervolemic
5. Consider biopsy If uncertain OR grade 3–4 AKI Confirms AIN vs glomerular; guides further management

When to Biopsy

Strongly consider if: - Persistent Grade 3–4 AKI after 3–5 days of corticosteroids - Rapidly worsening renal function despite treatment - Need to rule out alternative pathology (GN, thrombotic, infection) - Considering rechallenge with ICI

Pathology (Brief)

If a biopsy is done:

Finding Interpretation
Tubuloint. nephritis Lymphocytic infiltration of tubules and interstitium (dominant)
Tubular damage Acute tubular injury, flattened epithelium
Glomeruli Usually spared (unlike classic drug allergy); some cases show RPGN or membranous
IF microscopy Usually negative (no immune complex deposition)

Management Algorithm

Mild (Grade 1–2) AKI

Creatinine ≤1.5× baseline or <50% ↑ from pretreatment baseline

  1. Hold ICI — Pause immunotherapy during kidney injury recovery
  2. Supportive care — Ensure euvolemia, avoid nephrotoxins, monitor labs (Cr, BUN q2–3 days)
  3. Monitor & reassess — 60–70% recover spontaneously within 2–3 weeks
  4. Restart — If Cr recovers toward baseline AND clinical improvement, may cautiously resume ICI (risk of recurrence ~10–15%)

Moderate (Grade 2–3) AKI

Creatinine 1.5–3× baseline

  1. Hold ICI immediately
  2. Empiric corticosteroids:
    • Methylprednisolone 0.5–1 g IV daily × 1–3 days, then taper
    • OR Prednisone 0.5–1 mg/kg PO daily, taper over 4–6 weeks
  3. Supportive care — Hydration, avoid NSAIDs/ACEi if severely reduced GFR
  4. Monitor — Cr, BUN, electrolytes q2–3 days
  5. Response:
    • Good response (Cr ↓ 25%+ within 3–5 days) → Continue corticosteroid taper, consider resumption of ICI at completion of steroid course
    • Poor response (no improvement in 3–5 days) → Escalate to Grade 3–4 protocol

Severe (Grade 3–4) AKI

Creatinine >3× baseline OR need for dialysis

  1. Discontinue ICI — Permanent discontinuation typically recommended
  2. Aggressive corticosteroids:
    • Methylprednisolone 1 g IV daily × 3 days, then switch to PO prednisone 1 mg/kg daily with taper over 6–12 weeks
  3. Consider immunosuppression:
    • If no response within 3–7 days, add infliximab 5 mg/kg IV (TNF-α inhibitor)
    • Or mycophenolate mofetil (MMF) 1–1.5 g BID for RPGN-pattern disease
  4. Supportive:
    • Renal replacement therapy if oliguria, hyperkalemia, severe fluid overload, metabolic acidosis
    • Monitor closely; some patients require long-term dialysis (10–15%)
  5. Prognosis: 30–40% recover renal function; others have chronic kidney disease

Special Considerations

Combination Therapy (ICI + ICI)

  • Anti-CTLA-4 + anti-PD-1 (e.g., ipilimumab + nivolumab) = higher nephrotoxicity risk (~5–10%)
  • If AKI develops, usually higher grade → More likely to require aggressive immunosuppression

Atypical Presentations

  • Glomerular disease: Some patients develop RPGN, membranous nephropathy, or crescentic GN (10–20% of ICI-AKI)
    • Clue: RBC casts, hypertension, nephritic sediment → Biopsy
  • Hyperkalemia without severe AKI: Type 4 RTA-like picture (aldosterone suppression)

Monitoring After Recovery

  • Serial creatinine even after recovery (relapse possible)
  • If rechallenge ICI: More frequent Cr monitoring (weekly × 4, then biweekly)
  • Consider baseline and periodic kidney biopsy if considering re-initiation after Grade 3–4 AKI

Key Clinical Pearls

✓ Diagnosis: AIN on biopsy; sterile pyuria is a clue ✓ Timing: Usually 3–6 months post-ICI initiation ✓ Mild cases: Often resolve with ICI hold + supportive care ✓ Moderate–Severe: Require corticosteroids ± immunosuppression ✓ Escalate: If no improvement in 3–5 days → infliximab/MMF ✓ Prognosis: Mild/Mod often recover; Severe may require long-term dialysis

Related Clinical Content

For more detailed information, see the Onconephrology Hub:

  • ICI Fundamentals & Mechanisms — Deeper mechanistic review
  • ICI Kidney Injury: Diagnosis & Pathology — Comprehensive diagnostic algorithms
  • ICI Nephrotoxicity Treatment — Extended management protocols
  • ICI Glomerular Diseases — Atypical presentations (RPGN, MN, ANCA)

Cross-reference: - Acute Kidney Injury Hub — General AKI workup framework - Student Handout: AIN — Detailed acute interstitial nephritis overview

References

  • Kidney Disease: Improving Global Outcomes (KDIGO). Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease. 2021.
  • Cortazar FB, et al. Clinicopathological Features of Immune Checkpoint Inhibitor-Associated AKI. J Am Soc Nephrol. 2020;31(12):2861–2873.
  • Perazella MA, Sprangers B. Drug-Induced Acute Interstitial Nephritis. UpToDate. 2024.
  • Chowdhury TA, et al. Immunotherapy-Induced Nephropathy. Nephrology Self-Assessment Program. 2022.

Study Tips: - Use the management algorithm table when seeing ICI patients - Memorize the 3 grades and corresponding corticosteroid dosing - Remember: AIN is the dominant pathology; think of it like an immune drug allergy - Infliximab is your “rescue” drug for failures

Created: 2026-02-28

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