Osimertinib Dosing with eGFR 30 mL/min
No dose adjustment is required for osimertinib in patients with an eGFR of 30 mL/min—continue the standard dose of 80 mg once daily. 1
Evidence from FDA Drug Label
The FDA label for osimertinib (TAGRISSO) explicitly states that no clinically significant differences in pharmacokinetics were observed based on renal function with creatinine clearance ≥15 mL/min by Cockcroft-Gault 1. This means patients with eGFR 30 mL/min fall well within the range where standard dosing (80 mg once daily) is appropriate without adjustment.
The pharmacokinetic data demonstrate that osimertinib exposure is not meaningfully altered by moderate to severe renal impairment, as the drug is primarily eliminated via feces (68%) rather than urine (14%) 1.
Supporting Clinical Research
A dedicated phase I pharmacokinetic study specifically evaluated osimertinib in patients with severe renal impairment (CrCl <30 mL/min) compared to normal renal function 2. While osimertinib exposure was 1.85-fold higher in severe renal impairment patients, this increase was highly variable and showed no clear correlation with creatinine clearance. Importantly, no new safety signals emerged after 12 weeks of continuous 80 mg dosing in patients with severe renal impairment 2.
A Japanese pharmacokinetic study further confirmed these findings, showing similar PK parameters across patients with moderate renal impairment (eGFR 30-50 mL/min/1.73 m²) compared to normal renal function 3. The recommended dose remained 80 mg once daily for moderate renal impairment, though clinicians should monitor more carefully for toxicity 3.
Real-world evidence supports safe use even in end-stage renal disease: a case report documented successful treatment with osimertinib 80 mg/day for 41 cycles in a patient with ESRD not on hemodialysis, achieving complete radiological response without severe toxicities 4.
Clinical Monitoring Considerations
While no dose adjustment is needed, patients with eGFR 30 mL/min warrant closer monitoring because:
- Toxicity may occur more frequently in patients with impaired renal function, particularly acneiform rash, diarrhea, QTc prolongation, and interstitial lung disease 3
- The exposure variability is higher in renal impairment, though this doesn't translate to a consistent need for dose reduction 2
- Monitor for pseudo-worsening of kidney function: osimertinib can inhibit renal creatinine secretion, causing eGFR to decrease without true kidney injury 5. Consider cystatin C-based eGFR if creatinine-based eGFR drops significantly during treatment
Important Caveats
The only exception where osimertinib pharmacokinetics are unknown is in end-stage renal disease with CrCl <15 mL/min 1. For your patient with eGFR 30 mL/min, this does not apply.
Do not confuse this with other medications requiring dose adjustment at eGFR <30 mL/min (such as metformin, which should be avoided) 6, 7. Osimertinib's predominantly hepatic/fecal elimination pathway makes it fundamentally different from renally-cleared drugs.
Maintain standard 80 mg once daily dosing, but increase clinical vigilance for toxicity and consider more frequent monitoring of adverse effects during the first few months of therapy.