How should I manage a patient on Verzenio (abemaciclib) who develops elevated serum creatinine and glycosuria?

Management of Elevated Creatinine and Glycosuria in Patients on Verzenio (Abemaciclib)

Elevated serum creatinine in patients on Verzenio is most commonly a benign "pseudo-AKI" caused by inhibition of renal tubular creatinine secretion rather than true kidney injury, and should be confirmed with cystatin C or other biomarkers before adjusting cancer therapy or concomitant medications. 1, 2

Understanding Abemaciclib-Induced Creatinine Elevation

Mechanism of Creatinine Rise

• Abemaciclib inhibits organic cation transporter 2 (OCT2), multidrug and toxin extrusion protein (MATE) 1, and MATE2-K transporters in the proximal renal tubule, blocking creatinine secretion without affecting glomerular filtration 2, 3
• This results in reversible serum creatinine increases of 15–40% above baseline, typically grade 1 (8.3%) or grade 2 (91.7%) elevations 2, 4
• The median onset occurs at 21.5–42 days after treatment initiation, depending on the specific CDK4/6 inhibitor 4
• Creatinine returns to baseline after abemaciclib discontinuation 5

Distinguishing Pseudo-AKI from True Nephrotoxicity

The critical first step is to confirm whether the creatinine elevation represents true kidney injury or benign transporter inhibition. 1

Perform the following assessments:

• Measure serum cystatin C: This marker is not affected by tubular secretion and provides accurate GFR assessment 1, 6, 5
• Check blood urea nitrogen (BUN): BUN remains normal in pseudo-AKI but rises in true kidney injury 1
• Obtain urinalysis: Look for proteinuria, hematuria, or cellular casts that would indicate true renal pathology 1
• Measure urinary biomarkers (if available): Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) remain normal in pseudo-AKI 1, 2
• Consider measured GFR via renal scintigraphy if uncertainty persists, as this directly quantifies filtration independent of creatinine 6

If cystatin C, BUN, urinalysis, and urinary biomarkers are normal, the creatinine elevation is pseudo-AKI and does not require Verzenio dose modification. 1, 2

Management Algorithm

When Pseudo-AKI is Confirmed

• Continue Verzenio at current dose without modification, as no true renal injury has occurred 1, 2
• Do not adjust doses of concomitant renally-excreted medications based solely on creatinine-derived eGFR; use cystatin C-based GFR instead 5
• Approximately 22.6% of patients may have inappropriate dose adjustments of concomitant medications if creatinine alone is used 5
• Monitor cystatin C every 2–4 weeks initially, then monthly to ensure stable true GFR 7, 8

When True AKI is Suspected or Confirmed

If cystatin C is elevated, BUN is rising, or urinary markers indicate injury:

• Suspend Verzenio temporarily and investigate alternative causes 9
• Evaluate for volume depletion, nephrotoxic medications (NSAIDs, contrast), urinary obstruction, or concurrent illness 10, 7
• For Grade 2 creatinine elevation (2–3× baseline) with confirmed true AKI: Hold Verzenio, consult nephrology, and rule out other etiologies 10
• For Grade 3 elevation (≥3× baseline or ≥4.0 mg/dL): Permanently discontinue Verzenio if directly implicated in nephrotoxicity 10, 9
• Resume Verzenio at next lower dose (150 mg → 100 mg → 50 mg twice daily for combination therapy) only after creatinine resolves to ≤Grade 1 and true GFR is stable 9

Addressing Glycosuria

Evaluation of Glycosuria

• Check fasting glucose and HbA1c to assess for new-onset or worsening diabetes 11, 7
• Glycosuria in the absence of hyperglycemia suggests proximal tubular dysfunction (Fanconi syndrome), which is not a recognized adverse effect of abemaciclib 9
• If glycosuria occurs with normal glucose, consider alternative diagnoses: SGLT2 inhibitor use, hereditary tubulopathy, or other nephrotoxic agents 12, 8

Management of Hyperglycemia with Glycosuria

If hyperglycemia is present:

• Initiate or optimize diabetes therapy according to KDIGO guidelines: metformin (if eGFR ≥30 mL/min/1.73 m²) plus SGLT2 inhibitor as first-line 7, 8
• Add GLP-1 receptor agonist (e.g., semaglutide) if additional glycemic control is needed, as it requires no dose adjustment in CKD and provides cardiovascular protection 13, 14
• Avoid or reduce sulfonylureas (e.g., glimepiride) in patients with eGFR <30 mL/min/1.73 m² due to hypoglycemia risk 14, 15
• Target individualized HbA1c of <6.5% to <8.0% depending on comorbidities, hypoglycemia risk, and life expectancy 11, 7

Monitoring Strategy

Baseline and Ongoing Assessments

• Before starting Verzenio: Measure serum creatinine, cystatin C, BUN, urinalysis, fasting glucose, and HbA1c 9
• During first 2 months: Check creatinine and cystatin C every 2 weeks 9
• Months 3–4: Check monthly 9
• Thereafter: Check every 2–3 months or as clinically indicated 7, 8
• If creatinine rises: Immediately measure cystatin C, BUN, and urinalysis to differentiate pseudo-AKI from true injury 1, 5

Drug Interaction Considerations

• Abemaciclib significantly increases metformin exposure by inhibiting OCT2/MATE transporters 2
• Monitor for metformin toxicity (lactic acidosis risk) if both drugs are used; consider dose reduction of metformin if gastrointestinal symptoms or lactate elevation occur 2
• Metformin is contraindicated if true eGFR (cystatin C-based) falls below 30 mL/min/1.73 m² 12, 8

Common Pitfalls to Avoid

• Do not discontinue or dose-reduce Verzenio based on creatinine elevation alone without confirming true kidney injury with cystatin C 1, 5
• Do not adjust doses of concomitant medications (e.g., antibiotics, anticoagulants) using creatinine-based eGFR; use cystatin C-based GFR instead 5
• Do not assume glycosuria is drug-related without excluding diabetes or SGLT2 inhibitor use 12, 8
• Do not overlook true AKI: Rare cases of acute tubular injury and acute interstitial nephritis have been reported with CDK4/6 inhibitors 3
• Be aware that elderly patients (≥65 years) may have higher abemaciclib concentrations and increased risk of adverse events, including potential interstitial lung disease 16

Special Populations

Patients with Pre-existing CKD

• Abemaciclib-induced pseudo-AKI occurs across all CKD stages 4, 3
• In patients with baseline eGFR 30–60 mL/min/1.73 m², approximately 50% will experience a change in renal function classification after starting abemaciclib, though most represent pseudo-AKI 5
• Use cystatin C-based GFR for all medication dosing decisions in these patients 5

Patients on Diabetes Medications

• If patient is on metformin and develops pseudo-AKI with creatinine-based eGFR <45 mL/min/1.73 m² but cystatin C-based eGFR ≥45 mL/min/1.73 m², continue metformin at current dose 12, 8
• If true eGFR (cystatin C) is 30–45 mL/min/1.73 m², reassess metformin benefit-risk and consider dose reduction 12
• SGLT2 inhibitors and GLP-1 receptor agonists are safe alternatives that do not require dose adjustment based on renal function 8, 13