Our initial observation of the effect of crizotinib on serum creatinine and eGFR, the rapid onset and then plateauing of the effect, and equally rapid reversibility raised several etiological questions,
7- Brosnan EM
- Weickhardt AJ
- Lu X
- et al.
Drug-induced reduction in estimated glomerular filtration rate in patients with ALK-positive non-small cell lung cancer treated with the ALK inhibitor crizotinib.
specifically, whether these data reflected a true effect of crizotinib on kidney function or only on the accuracy of this particular method for assessing it, for example, through an effect on creatinine secretion. From case I, who had pre-existing renal damage, it is clear that crizotinib can affect both urinary creatinine clearance and iothalamate-based direct measures of the GFR, in addition to the creatinine-based eGFR. After 15 days of dosing, there was a 26% rise in creatinine, a 24% drop in eGFR as assessed by the CKD-EPI equation, and a 26% drop in the measured GFR as assessed by urinary creatinine clearance. Subsequently, on cessation of dosing with crizotinib, the patient manifested an 18% drop in serum creatinine (bringing the creatinine close to his pre-crizotinib levels), a 27% increase in eGFR as assessed by the CKD-EPI equation, and an 89% increase in GFR as assessed by iothalamate (
Figs. 1 and
2A). Iothalamate-based estimates of the GFR assume a “normal” distribution of intracellular and extracellular fluid. Beyond the background variability of the assessment (which has a reported coefficient of variation on repeated measurements of approximately 6–12%), only a true change in the GFR or significant changes in extravascular fluid accumulation (which did not occur) could explain the changes in the iothalamate readouts.
12Measured GFR as a confirmatory test for estimated GFR.
In addition, CEA, a serum tumor marker that is known to be renally excreted, which had been rising coincidently with the rise in creatinine, despite a rapid and persistent metabolic and radiographic complete response, then manifested a 50% reduction after cessation of dosing with crizotinib, despite no other change in the patient's anticancer therapy or additional radiographic change in his cancer (
Fig. 1).
14- Zeferos N
- Digenis GE
- Christophoraki M
- et al.
Tumor markers in patients undergoing hemodialysis or kidney transplantation.
Given the changes in both iothalamate readings and CEA, a true effect of crizotinib on GFR has to be concluded, although an additional creatinine secretion effect cannot be ruled out. Certainly, the decrease in urinary creatinine (8%) with crizotinib in this one patient was below the mean reduction seen with other drugs that are known to interfere with creatinine secretion but was still within the range reported.
15- Zaltzman JS
- Whiteside C
- Cattran DC
- Lopez FM
- Logan AG
Accurate measurement of impaired glomerular filtration using single-dose oral cimetidine.
An acute event may have been associated with the immediate rise in the creatinine at the point when the decision was made to discontinue the patient's dosing as these values were improving before discontinuing dosing. However, the overall trend had been of worsening renal function for several months previously, and as values fell further on discontinuation of crizotinib dosing, consistent with our prior recovery data set, the contribution of crizotinib exposure to the measured GFR readings remains unequivocal.
7- Brosnan EM
- Weickhardt AJ
- Lu X
- et al.
Drug-induced reduction in estimated glomerular filtration rate in patients with ALK-positive non-small cell lung cancer treated with the ALK inhibitor crizotinib.
How much the effect on the measured GFR reflects a direct effect of crizotinib on the kidney, for example, through pharmacological inhibition of, as yet unknown, kinases involved in kidney function, versus an indirect effect, for example, secondary to renal hypoperfusion due to crizotinib-associated bradycardia remains uncertain. His blood pressure at the time of the bradycardia was neither markedly reduced nor elevated (115/68), but this does not preclude an effect of the bradycardia on cardiac output and consequently on renal perfusion per se as the local vasculature in the kidneys may not be reflective of the whole.
Case 2 also demonstrated results potentially consistent with both slow-onset direct effects of crizotinib on the GFR and rapid-onset effects on creatinine secretion. Of note, unlike case 1, case 2 did not have pre-existing kidney damage, and although there was again a suggestion of a crizotinib-associated reduction in heart rate from baseline values, his heart rate never reached the bradycardic levels of case 1. Prolonged exposure to crizotinib was associated with a 73% increase in the patient's creatinine and a 47% reduction in his eGFR, as assessed by the CKD-EPI equation, values too high to be explained by a pure creatinine secretion effect.
10- Burgess E
- Blair A
- Krichman K
- Cutler RE
Inhibition of renal creatinine secretion by cimetidine in humans.
,
11- Kastrup J
- Petersen P
- Bartram R
- Hansen JM
The effect of trimethoprim on serum creatinine.
Subsequently, exploiting a break in crizotinib dosing for radiation therapy to obtain measures of kidney function taken before and after crizotinib exposure, cessation of crizotinib dosing was associated with a rapid 17% drop in serum creatinine and a 28% increase in eGFR as assessed by the CKD-EPI equation. Importantly, on recommencement of crizotinib dosing, although, as expected, there was a 28% rise in serum creatinine and a 27% decrease in eGFR as assessed by the CKD-EPI equation, there was no decrease in the measured GFR by iothalamate; instead there was actually a 16% increase in GFR from the initial iothalamate assessment. Assuming that some degree of intrapatient variability in iothalamate readings may be allowed for or that ongoing treatment of the underlying cancer may be marginally beneficial to renal function, here the suggestion is that crizotinib is not acutely affecting the true GFR but only the creatinine-based estimates of GFR, consistent with, for example, an effect on creatinine secretion.
Overall, these two cases illustrate what may be a range of different effects on kidney function associated with crizotinib use. Whereas in some situations crizotinib's effects on kidney function may be restricted to interfering with assessments that are creatinine-based with minimal to no effect on the “true” GFR, in other situations, particularly after prolonged exposure, a clear reduction in the “true” GFR assessed through multiple different means can occur. Consequently, consistent with our previous recommendations, if crizotinib-associated changes in creatinine-based kidney function are making practitioners consider a change in dosing with either crizotinib or concomitant medications that are renally excreted, use of a non-creatinine–based assessment of kidney function, such as iothalamate assessments, should be considered before making a final decision.