Does an Alternative Sunitinib Dosing Schedule Really Improve Survival Outcomes over a Conventional Dosing Schedule in Patients with Metastatic Renal Cell Carcinoma? An Updated Systematic Review and Meta-Analysis

Real-World Results of Cabozantinib Given as Alternative Schedule in Metastatic Renal Cell Carcinoma

BACKGROUND

The multikinase-inhibitor Cabozantinib is a widely used treatment strategy in metastatic renal cell carcinoma (mRCC), either in combination with the programmed cell death protein-1 (PD-1) inhibitor nivolumab or as monotherapy. Cabozantinib is given continuously at a dose of 60 mg once daily when used as a single agent and at 40 mg when combined with nivolumab. Treatment-related adverse events (TRAE's) were shown to occur frequently.

OBJECTIVE

We aimed to assess the safety and efficacy of cabozantinib in patients with mRCC. Patients were treated in various lines. Furthermore, we analyzed the impact of an alternative treatment schedule in patients not able to maintain continuous dosing.

PATIENTS

This is a single center retrospective study from the Medical University of Vienna.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Overall response rates (ORR), progression free survival (PFS) and overall survival (OS) were evaluated for the entire cohort, by treatment line and by treatment schedule.

RESULTS

Between January 2014 until April 2021, 71 patients received cabozantinib. Sixty-seven patients were eligible for full evaluation. By IMDC criteria, 32.4%, 59.2%, and 8.5% were classified as favorable, intermediate and poor risk respectively. Cabozantinib was offered as a 2nd-line or 3rd-line treatment in 38.0% and 32.4% of patients, respectively. An alternative treatment schedule was offered in 39.1% of patients. Objective responses were found in 43.3% (CR 6%) of patients and the median PFS was 10.8 months (95% CI: 5.5-16.2). When compared to continuous dosing, an alternative treatment schedule was associated with longer PFS (12.2 months (95% CI: 0-25.5) vs. 6.1 months (95% CI: 0.37-11.8) (P = .014, HR 0.46 (95% CI: 0.24-0.86), respectively) and a lower frequency and severity of TRAE's.

CONCLUSIONS

Safety and efficacy of cabozantinib in real world is comparable to what has been observed in the pivotal trials, irrespective of the treatment line. An alternative schedule may further improve efficacy and safety.

Systematic review and cost-effectiveness of pharmacokinetically guided sunitinib individualized treatment for patients with metastatic renal cell carcinoma

Background:

Sunitinib has a narrow therapeutic window, with considerable differences between patients. Dosing based on pharmacokinetics (PK) may help overcome some of those issues. This study aims to evaluate and compare the cost-effectiveness of PK-guided individualized treatment of sunitinib with its standard dose in patients with metastatic renal cell carcinoma (mRCC).

Methods:

A comprehensive literature search was performed, and relevant values were used to provide information for the decision analysis model. Utility data were derived from published studies, and costs were obtained from the perspective of payers in China and the United States. A Markov model was established to evaluate the associated costs and health outcomes for patients. The primary outputs of the model included lifetime costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER). One-way and probability sensitivity analyses were conducted to evaluate the potential uncertainties of parameters.

Results:

Cost-effective analysis showed that the QALY of the PK-guided group increased by 0.83 compared with that in the standard dose group. From the perspective of both countries’ health systems, the cost of PK-guided dose was lower than that of standard dose. Hence, PK-guided treatment was the dominant strategy. One-way and probability sensitivity analyses confirmed the reliability of these results.

Conclusion:

On the basis of currently available data, PK-guided sunitinib treatment may be a safe, effective, and economical intervention for patients with mRCC.

Adaptive dosing of sunitinib in a metastatic renal cell carcinoma patient: when in silico modeling helps to go quicker to the point

PURPOSE

Adaptive dosing strategy with oral targeted therapies in oncology is mostly based upon clinical signs. Using pharmacokinetics (PK) models to customize dosing could help saving time, i.e., by predicting clinical outcome through early monitoring of drug levels.

CASE REPORT

We present the case of a metastatic renal cell carcinoma patient treated with standard Sunitinib dosing (i.e., 50 mg QD). Clinical signs suggested lack of efficacy. Therapeutic Drug Monitoring (TDM) confirmed that exposure was below the expected target exposure. PK modeling suggested that dosing could be increased safely to 75 mg QD. Sunitinib dosing was instead changed empirically to 62.5 mg only, increasing drug exposure to the lower part of the therapeutic window. Resolution of bone pains plus Stable Disease were observed. Even though further modeling suggested to increase Sunitinib dosing to 75 mg again, the intermediate dosing was maintained for the subsequent cycles to preserve the safety. Unfortunately, severe pains plus degradation of the general state were reported and imaging showed Progressive Disease. The patient was finally switched to alternative therapy, without being treated at the 75 mg level of Suntitinib.

CONCLUSIONS AND DISCUSSION

This case suggests that model-based adaptive dosing could have allowed to reach quicker the best dosing with Sunitinib, thus possibly ensuring a better management of this patient. Model-informed dosing should be used instead of empirical search for the most appropriate dosing to ensure a good benefit/risk ratio with Sunitinib, especially in the context of such aggressive disease.