Re: prediction of carboplatin clearance from standard morphological and biological patient characteristics

Carboplatin Dosing Accuracy by Estimation of Glomerular Filtration versus Creatinuria in Cancer Patients

Background: The glomerular filtration rate (GFR) is essential for calculating the dose and the monitoring of carboplatin. Although GFR measurement (mGFR) by external markers is ideal, in most cases these are not employed; the most used method is GFR estimation (eGFR) by formulae, hence the need to identify the formula with the best performance. Methods: Patients admitted between 2011 and 2017 and diagnosed with ovarian, endometrial, lung, esophageal, or testicular cancer were assessed retrospectively. The accuracy of the carboplatin dose calculated by creatinine concordance and by the Cockroft-Gault (CG), CKD-EPI, MDRD, Wright, and Jelliffe formulae was assessed using the intraclass correlation coefficient. Results: Fifty-six medical histories were analyzed. The best accuracy was observed between the Wright formula (i.e., 0.71) and the dose calculated based on the 24-h creatinine clearance. Stratification by CKD was made in depurations < 60 mL/min, where the Jelliffe value was excellent (i.e., 0.75). In depurations ≥60 mL/min, CKD-EPI was the best formula, with an accuracy of 0.65. CG was the formula with the worst performance in calculating the dose and glomerular filtration, losing its usefulness with very low filtrations. Conclusions: GFR formulae and calculation of the carboplatin dose have good accuracy with the GFR obtained based on the 24-h creatinine clearance, with the Wright formula being the one with best performance and CG the one with worst performance.

Validity of new methods to evaluate renal function in cancer patients treated with cisplatin

Purpose

Creatinine clearance (Ccr) is used as a marker of renal function in cancer chemotherapy, but it is not correlated with glomerular filtration rate (GFR) after high-dose cisplatin treatment. In addition to Ccr, measured using 24-h urine collection (24-h Ccr) or Cockcroft–Gault formula (CGF), the Chronic Kidney Disease Epidemiology Collaboration (CKD–EPI) equation and the Japanese GFR estimation equation (the Japanese equation) have been recently developed to estimate GFR for predicting renal function. However, these equations remain to be evaluated, particularly in cancer patients treated with cisplatin. Therefore, we investigated the validity of these equations for predicting the GFR in cancer patients treated with cisplatin.

Methods

GFR was measured by inulin clearance (Cin) in 50 cancer patients and compared with GFR estimated by the CKD–EPI equation, the Japanese equation, and Ccr estimated by CGF or measured by 24-h Ccr before the first and third cisplatin-containing chemotherapy cycles (considered pretreatment and posttreatment, respectively).

Results

Before treatment, the CKD–EPI and the Japanese equations estimated GFR with higher accuracy than Ccr. Posttreatment bias values for GFR estimation using the CKD–EPI and the Japanese equations were lower than those for Ccr. The CKD–EPI and the Japanese equations were also more precise than Ccr. However, for patients with low renal function, these equations still overestimated Cin.

Conclusion

The CKD–EPI and the Japanese equations estimated GFR with lower bias and higher precision than Ccr pre- and postcisplatin treatment. This study is registered at UMIN: 000002167.

Prediction of glomerular filtration rate in cancer patients by an equation for Japanese estimated glomerular filtration rate

BACKGROUND

Assessment of renal function is important for safe cancer chemotherapy, and eligibility criteria for clinical trials often include creatinine clearance. However, creatinine clearance overestimates glomerular filtration rate, and various new formulae have been proposed to estimate glomerular filtration rate. Because these were developed mostly in patients with chronic kidney disease, we evaluated their validity in cancer patients without kidney disease.

METHODS

Glomerular filtration rate was measured by inulin clearance in 45 Japanese cancer patients, and compared with creatinine clearance measured by 24-h urine collection as well as that estimated by the Cockcroft-Gault formula, Japanese estimated glomerular filtration rate developed in chronic kidney disease patients, the Modification of Diet in Renal Disease study equation and the Chronic Kidney Disease Epidemiology Collaboration equation. The Modification of Diet in Renal Disease study and Chronic Kidney Disease Epidemiology Collaboration equations were adjusted for the Japanese population by multiplying by 0.808 and 0.813, respectively.

RESULTS

The mean inulin clearance was 79.2 ± 18.7 ml/min/1.73 m(2). Bias values to estimate glomerular filtration rate for Japanese estimated glomerular filtration rate, the Cockcroft-Gault formula, creatinine clearance measured by 24-h urine collection, the 0.808 × Modification of Diet in Renal Disease study equation and the 0.813 × Chronic Kidney Disease Epidemiology Collaboration equation were 0.94, 9.75, 29.67, 5.26 and -0.92 ml/min/1.73 m(2), respectively. Precision (root-mean square error) was 14.7, 22.4, 39.8, 16.0 and 14.1 ml/min, respectively. Of the scatter plots of inulin clearance versus each estimation formula, the Japanese estimated glomerular filtration rate correlated most accurately with actual measured inulin clearance.

CONCLUSION

The Japanese estimated glomerular filtration rate and the 0.813 × Chronic Kidney Disease Epidemiology Collaboration equation estimated glomerular filtration rate with lower bias and higher precision than the other formulae. We therefore propose Japanese estimated glomerular filtration rate for the estimation of glomerular filtration rate in Japanese cancer patients.

Evaluation of creatinine-based formulas in dosing adjustment of cancer drugs other than carboplatin

Background. Glomerular filtration rate (GFR) is often used to determine initial dosing of renally excreted cancer drugs. GFR can be calculated using the Cockcroft-Gault (CG) or the modified diet in renal diseases (MDRD) study formulas, both of which are based on serum creatinine levels. The MDRD formula is more accurate in noncancer patients, does not require patient weight, and is reported automatically by all laboratories in British Columbia, Canada. We previously showed that the CG and MDRD formulas have similar accuracy for carboplatin dosing in patients with gynecological malignancies. We now examine dosing of all renally excreted cancer drugs in the general cancer population. Since this setting does not include routine measurement of GFR, we report the concordance of estimates of GFR derived from the CG and MDRD formulas.

Methods. Patient data were collected retrospectively at the BC Cancer Agency. The primary outcome was the proportion of patients who would have received a different initial dose due to difference in the GFR. Each patient’s dose was determined from dose adjustment tables stated in specific treatment protocols. The secondary outcome was concordance of the GFR derived from CG and MDRD, using the method of Bland and Altman. A difference of >30% was assumed to be clinically significant because this difference would usually lead to dose adjustment based on reclassification of renal function.

Results. A total of 313 patients were evaluated, with 40% male. The median age was 56 years, weight 67.5 kg, height 166 cm, and serum creatinine 74 µmol/L (0.84 mg/dL). The median GFR derived from the CG and MDRD formulas were 86.8 mL/min (mean 91 mL/min, SD ± 30 mL/min) and 87.6 mL/min (mean 88 mL/min, SD ± 26 mL/min), respectively. A total of 8.6% (27/313) of patients would have received a different dose due to difference in the GFR; of these, 67% (18/27) would have received a higher dose. A difference of >30% in GFR was found in 17.9% (56/313) of patients.

Conclusions. There is good concordance of the GFR derived from the CG and MDRD formulas for most cancer patients, with less than 10% of patients expected to receive a different initial dose of chemotherapy. The MDRD formula may be a reasonable alternative to the CG formula for dosing of cancer drugs which are renally excreted or nephrotoxic. J Oncol Pharm Practice (2010) 16: 113—119.

A phase I study and pharmacologic evaluation of irinotecan and carboplatin for patients with advanced ovarian carcinoma who previously received platinum-containing chemotherapy

BACKGROUND

The objectives of the current study were to determine the maximum tolerated dose (MTD) of irinotecan and carboplatin in combination, to evaluate the efficacy and toxicity of the combination in patients with advanced ovarian carcinoma who previously received platinum-containing chemotherapy, and to examine the pharmacokinetics and pharmacodynamics of both drugs by using the Chatelut formula.

METHODS

Patients with advanced ovarian carcinoma who previously received platinum-containing chemotherapy were treated with a combination of irinotecan and carboplatin. Carboplatin was administered as a 60-minute intravenous infusion on Day 1 and was followed by irinotecan, which was administered as a 90-minute intravenous infusion on Days 1, 8, and 15. Six dose levels of irinotecan (in mg/m(2))/carboplatin (mg . mL/min) were planned: 50 mg/m(2)/4 mg . mL/minute, 60 mg/m(2)/4 mg . mL/minute, 50 mg/m(2)/5 mg . mL/minute, 60 mg/m(2)/5 mg . mL/minute, 50 mg/m(2)/6 mg . mL/minute, and 60 mg/m(2)/6 mg . mL/minute. The carboplatin dosage was calculated by using the Chatelut formula. Treatment was repeated at 28-day intervals.

RESULTS

In total, 19 patients in cohorts of 3 to 5 patients received irinotecan and carboplatin at 5 dose levels. The dose-limiting toxicities were Grade 4 neutropenia and Grade 4 thrombocytopenia. The MTD of the irinotecan/carboplatin combination was 60 mg/m(2)/5 . mg mL/minute. Partial responses were observed at higher dose levels. Pharmacologic studies demonstrated that administration of the dosage estimated with the Chatelut formula instead of the Chatelut formula with adjustment for serum creatinine resulted in a slightly excessive dose of carboplatin.

CONCLUSIONS

The recommended dose for the Phase II study was irinotecan 60 mg/m(2) on Days 1, 8, and 15 with carboplatin 5 mg/mL . minute on Day 1 repeated every 4 weeks.