Outcomes and Drug Costs of Sunitinib Regimens for Metastatic Renal Cell Carcinoma: A Provincial Population-Based Study

BACKGROUND

Conventional sunitinib dosing in metastatic renal cell carcinoma (mRCC) administers 50 mg daily on a 4 weeks on/2 weeks off (4/2) schedule. Not all patients tolerate this regimen and many undergo modifications to schedule, dose, or both.

MATERIAL AND METHODS

All patients with mRCC treated with sunitinib by the Saskatchewan Cancer Agency between January 1, 2006, and January 1, 2013, were included. Regimens were categorized as standard intermittent dosing (SID), modified intermittent schedule (MIS), modified intermittent dosing (MID), combination of modified schedule and dosing (MSD), or continuous dosing (CD). The primary objective was to compare overall survival (OS) between regimens. Secondary outcomes included progression-free survival (PFS), discontinuation due to adverse effects (AE), and medication cost.

RESULTS

Among 161 patients, 18.0%, 51.6%, and 30.4% had favorable, intermediate, and poor Heng risk prognoses, respectively. A total of 140 (87.0%) received sunitinib as first-line therapy. MID was associated with longer OS compared with SID (estimated median 28.4 vs. 11.2 months). PFS was longer for MID, MSD, and CD compared with SID (estimated median 12.0, 9.0, and 8.0 months vs. 3.0 months, respectively). Adjustment for potential confounders did not negate these associations. SID also had higher average monthly drug costs than MIS, MID, and MSD. Overall discontinuation rate due to AE was high (24%).

CONCLUSION

An adjusted-dose sunitinib regimen is associated with improved OS and PFS over SID, with lower costs. The development of toxicities requiring dose reductions serves as a predictive biomarker for better outcomes.

Neoadjuvant antiangiogenic therapy reveals contrasts in primary and metastatic tumor efficacy

Thousands of cancer patients are currently in clinical trials evaluating antiangiogenic therapy in the neoadjuvant setting, which is the treatment of localized primary tumors prior to surgical intervention. The rationale is that shrinking a tumor will improve surgical outcomes and minimize growth of occult micrometastatic disease—thus delaying post-surgical recurrence and improving survival. But approved VEGF pathway inhibitors have not been tested in clinically relevant neoadjuvant models that compare pre- and post-surgical treatment effects. Using mouse models of breast, kidney, and melanoma metastasis, we demonstrate that primary tumor responses to neoadjuvant VEGFR TKI treatment do not consistently correlate with improved post-surgical survival, with survival worsened in certain settings. Similar negative effects did not extend to protein-based VEGF pathway inhibitors and could be reversed with altered dose, surgical timing, and treatment duration, or when VEGFR TKIs are combined with metronomic ‘anti-metastatic’ chemotherapy regimens. These studies represent the first attempt to recapitulate the complex clinical parameters of neoadjuvant therapy in mice and identify a novel tool to compare systemic antiangiogenic treatment effects on localized and disseminated disease.

A 2 weeks on and 1 week off schedule of sunitinib is associated with decreased toxicity in metastatic renal cell carcinoma

Treatment of metastatic renal cell carcinoma (mRCC) with sunitinib is often associated with toxicity necessitating dose reduction. Maintaining adequate dosing and drug levels are essential for optimising clinical efficacy. Standard sunitinib schedule is 4 weeks of treatment and 2 weeks of rest (schedule 4/2). Empirically, several mRCC patients at The Cleveland Clinic (CCF) have been changed from schedule 4/2 to 2 weeks of treatment/1 week off (schedule 2/1) after experiencing toxicity, in an attempt to maintain daily dosing. The medical records of 30 mRCC patients on sunitinib who were changed from schedule 4/2 to schedule 2/1 at CCF were retrospectively reviewed. Toxicity on each schedule was recorded during routine clinic visits and graded using Common Toxicity Criteria, version 4.0. 97% of patients on schedule 4/2 had grade 3 or 4 toxicity that led to changing to schedule 2/1. There were no grade 4 toxicities on schedule 2/1, and 27% of patients experienced grade 3 toxicity (p=0.0001). Two of the most common toxicities, fatigue and hand-foot syndrome (HFS), were significantly less frequent on schedule 2/1 than on schedule 4/2 (p=0.0003; p=0.0004, respectively). Median overall treatment duration on schedule 4/2 was 12.6 months (range 1.2 months-5.1 years) and median overall treatment duration on schedule 2/1 was 11.9 months (range 0.9+ to 73.3+ months). Treatment with sunitinib on schedule 2/1 is associated with significantly decreased toxicity in patients who experience grade 3 or greater toxicity on schedule 4/2, and can extend treatment duration considerably. Prospective clinical trials are required to define the optimal sunitinib schedule to balance efficacy and toxicity.

Anti-VEGF therapy in mRCC: differences between Asian and non-Asian patients

Background:

Several reports suggest that vascular endothelial growth factor (VEGF)-targeted therapy in metastatic renal cell carcinoma (mRCC) may be more toxic in Asian vs non-Asian populations. Comparative efficacy of these agents with respect to ethnicity is not well characterised.

Methods:

A multicentre, retrospective, cohort study using Asian and non-Asian centres which collected data on ethnicity, dose reductions and outcomes using the International mRCC Database Consortium.

Results:

This study included 1024 (464 Asian, 560 non-Asian) patients with a 29.4 months median follow-up. The percentage of dose modifications/reductions between non-Asians and Asians was similar (55% vs 61% P=0.1197). When adjusted for risk groups, there was no difference in overall or progression-free survival between non-Asians and Asians. Patients with dose reductions due to toxicity had longer treatment durations and overall survival than those who did not in both non-Asian (10.6 vs 5.0 months, P<0.0001; 22.6 vs 16.1 months, P=0.0016, respectively) and Asian populations (8.9 vs 5.4 months, P=0.0028; 28.0 vs 18.7 months, P=0.0069, respectively).

Conclusions:

Adjusting for risk groups, there appears to be no difference in outcome between Asian vs non-Asian patients with mRCC treated with VEGF-targeted therapy. Judicious dose reductions may allow for better outcomes in both populations due to longer treatment durations, but direct comparisons are needed.