Optimizing carboplatin dosing by an improved prediction of carboplatin clearance using a CT-enhanced estimate of renal function

AIMS

Carboplatin is generally dosed based on a modified Calvert formula, in which the Cockcroft-Gault-based creatinine clearance (CRCL) is used as proxy for the glomerular filtration rate (GFR). The Cockcroft-Gault formula (CG) overpredicts CRCL in patients with an aberrant body composition. The CT-enhanced estimate of RenAl FuncTion (CRAFT) was developed to compensate for this overprediction. We aimed to evaluate whether carboplatin clearance is better predicted by CRCL based on the CRAFT compared to the CG.

METHODS

Data of four previously conducted trials was used. The CRAFT was divided by serum creatinine to derive CRCL. The difference between CRAFT- and CG-based CRCL was assessed by population pharmacokinetic modelling. Furthermore, the difference in calculated carboplatin dose was assessed in a heterogeneous dataset.

RESULTS

In total, 108 patients were included in the analysis. Addition of the CRAFT- and CG-based CRCL as covariate on carboplatin clearance led, respectively, to an improved model fit with a 26-point drop in objective function value and a worsened model fit with an increase of 8 points. In 19 subjects with serum creatinine <50 μmol/L, the calculated carboplatin dose was 233 mg higher using the CG.

CONCLUSIONS

Carboplatin clearance is better predicted by CRAFT vs. CG-based CRCL. In subjects with low serum creatinine, the calculated carboplatin dose using CG exceeds the dose using CRAFT, which might explain the need for dose capping when using the CG. Therefore, the CRAFT might be an alternative for dose capping while still dosing accurately.

Carboplatin dosing in the treatment of ovarian cancer: An NRG oncology group study

OBJECTIVE

To determine the effects of using National Comprehensive Cancer Network (NCCN) guidelines to estimate renal function on carboplatin dosing and explore adverse effects associated with a more accurate estimation of lower creatinine clearance (CrCl).

METHODS

Retrospective data were obtained for 3830 of 4312 patients treated on GOG182 (NCT00011986)-a phase III trial of platinum-based chemotherapy for advanced-stage ovarian cancer. Carboplatin dose per patient on GOG182 was determined using the Jelliffe formula. We recalculated CrCl to determine dosing using Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault (with/without NCCN recommended modifications) formulas. Associations between baseline CrCl and toxicity were described using the area under the receiver operating characteristic curve (AUC). Sensitivity and positive predictive values described the model's ability to discriminate between subjects with/without the adverse event.

RESULTS

AUC statistics (range, 0.52-0.64) showed log(CrClJelliffe) was not a good predictor of grade ≥3 adverse events (anemia, thrombocytopenia, febrile neutropenia, auditory, renal, metabolic, neurologic). Of 3830 patients, 628 (16%) had CrCl <60 mL/min. Positive predictive values for adverse events ranged from 1.8%-15%. Using the Cockcroft-Gault, Cockcroft-Gault with NCCN modifications, and MDRD (instead of Jelliffe) formulas to estimate renal function resulted in a >10% decrease in carboplatin dosing in 16%, 32%, and 5.2% of patients, respectively, and a >10% increase in carboplatin dosing in 41%, 9.6% and 12% of patients, respectively.

CONCLUSION

The formula used to estimate CrCl affects carboplatin dosing. Estimated CrCl <60 mL/min (by Jelliffe) did not accurately predict adverse events. Efforts continue to better predict renal function. Endorsing National Cancer Institute initiatives to broaden study eligibility, our data do not support a minimum threshold CrCl <60 mL/min as an exclusion criterion from clinical trials.

Effect of carboplatin dose capping on survival in recurrent breast, ovary and head and neck cancers: a single institutional retrospective study

INTRODUCTION

Carboplatin based regimens are an integral part of chemotherapy regimens for recurrent head and neck cancers (rHNC), triple negative breast cancers (rTNBC) and ovarian cancers (rOC). Dose reduction/capping of carboplatin remains a controversial aspect of such regimens in patients with moderate creatinine clearance (50 ml/min to 125 ml/min), especially in resource limited setting. The authors, therefore, looked into the magnitude of difference in outcome this makes in the above mentioned subsites.

METHODS

This single institutional retrospective study was performed with a total of 120 patients divided equally into Group A (patients receiving capped dose) and Group B (patients receiving uncapped dose). Further matching was performed with respect to age, sex, body surface area, weight, and primary malignancy subsite and baseline creatinine clearance. Patients in Group A had received 450 mg (for AUC 6 regimens) and 150 mg (for AUC 2 regimens) of carboplatin while patients in Group B received the actual calculated dose of carboplatin determined by the Calvert formula. Median progression free survival (mPFS) and median overall survival (mOS) were the co-primary outcome measures.

RESULTS

At a median follow-up of 24 months, compared to Group A, Group B had a higher mPFS and mOS by 4 months (p < .001) and 5.5 months (p < .001), respectively. Statistically significant difference in outcome favouring Group B extends to all primary tumour subsites, with mPFS difference being 3.1 months (rHNC), 5.1 months (rTNBC) and 4.5 months (rOC) and mOS difference being 4.2 months (rHNC), 3 months (rTNBC) and 5.6 months (rOC). It was also found that capping had a statistically significant detriment in distal failure (p = .042) compared to locoregional failure (p = .842). A higher proportion of hematotoxicity was found in Group B, however, it was not statistically significant and well manageable.

CONCLUSIONS

Blatant dose capping of carboplatin should be avoided probably with more caution in patients with distant disease recurrence compared to their counterparts with locoregional failure.

Carboplatin dose capping affects pCR rate in HER2-positive breast cancer patients treated with neoadjuvant Docetaxel, Carboplatin, Trastuzumab, Pertuzumab (TCHP)

PURPOSE

Estimated glomerular filtration rate (eGFR) is commonly used to calculate carboplatin doses and capping the eGFR may be used to reduce the risk of excessive dosing and toxicity. We sought to retrospectively examine the impact of our carboplatin guidelines on pathological complete response rates (pCR) and toxicity in women with HER2+ breast cancer receiving neoadjuvant docetaxel, carboplatin, trastuzumab and pertuzumab (TCHP).

METHODS

The delivered area under the curve (dAUC) was calculated [(actual carboplatin dose at cycle 1 ÷ dose calculated with uncapped/unbanded eGFR) × 6] and dichotomized at the median value. The impact of this and other clinical factors on pCR rate, dose intensity (DI) and toxicity was assessed.

RESULTS

124 eligible patients were identified of whom 63.7% (79/124) achieved pCR. The median dAUC at cycle 1 was 5.75 mg × ml/min. Those with lower dAUC were more frequently younger and overweight/obese. Patients with lower dAUC had significantly inferior pCR rates of 54.8% (34/62) vs 72.6% (45/62), respectively (p = 0.040). Similar results were seen in the ER+ subgroup; 45.2% (19/42) vs 68.3% (28/41), p = 0.037%, whereas no significant difference was seen among ER- patients; 75.0% (15/20) vs 81.0% (17/21), p = 0.72. DI and toxicity were comparable between the two dAUC groups.

CONCLUSIONS

The overall pCR rate was high in patients with HER2+ breast cancer receiving the TCHP regimen; however, carboplatin dose capping resulted in inferior pCR rates, particularly in the ER+ subgroup. To ensure optimal dosing, isotopic measurement of renal function is warranted in patients who would otherwise have their eGFR and dose capped.