Introduction:
Targeted cancer therapies have revolutionized oncology by selectively attacking specific molecular pathways, improving clinical outcomes. However, therapies like palbociclib can cause asymptomatic increases in serum creatinine levels by inhibiting active tubular secretion. This case underscores the importance of using non-creatinine-based markers for kidney function assessment in patients treated with such therapies
Methods:
A 71-year-old hypertensive woman, treated for 22 years with irbesartan (300 mg) and moxonidine (0.4 mg), was referred for worsening of her renal function. She had no microscopic hematuria and a urine albumin-to-creatinine ratio of 25 mg/g. Diagnosed with invasive mammary carcinoma, she was treated with letrozole, an aromatase inhibitor followed by palbociclib, a selective cyclin-dependent kinase inhibitor. Before starting cancer treatment, her eGFR was estimated to be between 30 and 35 ml/min/1.73 m² using the CKD-EPI formula adjusted for body surface area. After starting palbociclib, her plasma creatinine gradually increased over 6 months, reaching 250 µmol/L, corresponding to an eGFR of 18 ml/min/1.73 m² (CKD-EPI), despite well-controlled blood pressure. There was no history of pre-renal events or obstruction
Results:
In the absence of other clinical or biochemical indicators of renal function deterioration, serum cystatin C measured by an immunoturbidimetric assay was 1.65 mg/L (normal range: 0.62-1.11), corresponding to an eGFR of 36 ml/min/1.73 m² according to the CKD-EPI cystatin equation (2012), consistent with her baseline figures prior to starting treatment with palbociclib. These findings suggested that the decrease in eGFR measured by serum creatinine was due to palbociclib’s inhibition of tubular creatinine secretion through its direct effects on kidney transporters, rather than actual kidney damage. After these results, no therapeutic changes were made for this patient
Conclusions:
Employing non-creatinine-based markers such as cystatin C provides a more accurate estimation of kidney function in patients receiving targeted cancer therapies like palbociclib, which influence tubular creatinine secretion. This approach ensures better management and monitoring of potential renal side effects in oncology patients
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.