Updated Treatment Protocol May Reduce Toxicities in Renal Cancer Patients

Metastatic renal cell carcinoma (mRCC) patients may have improved quality of life and suffer significantly fewer side effects with a new protocol that calls for an attenuated-dose regimen of sunitinib (Sutent). The genitourinary (GU) oncology team at the National Cancer Centre Singapore (NCCS) has found that an attenuated regimen of sunitinib reduces toxicities for Asian patients with mRCC.

The researchers conducted a 7-year study which began in 2007. During that year, the attenuated-dose regimen was widely adopted in Singapore. The attenuated-dose regimen of sunitinib for patients with mRCC consists of a lower dosage and it cut the cost of the drug by 30%. The US Food and Drug Administration (FDA) approved dosing of sunitinib as 50 mg once daily for four weeks, followed by a 2-week break in a 6-week treatment cycle (conventional-dose regimen). However, after the drug came on the market, it was noticed by clinicians that high toxicities were occurring with the conventional dosing especially in Asians.

Study investigator Tan Min Han, MD, PhD, who is a Visiting Consultant in the Division of Medical Oncology at NCCS, said many Asian patients were experiencing severe side effects of grade 3 or higher with the conventional dosing. So, a goal was established that refine the treatment protocol to improve patients' quality of life. It appears this approach has been highly successful.

The researchers initiated a prospective clinical registry with 127 mRCC patients receiving attenuated sunitinib dosing of 37.5 mg once daily for 4 weeks, followed by a 2-week break as treatment protocol in 2007. The researchers then compared the clinical data of patients receiving the attenuated-dose regimen of sunitinib from 2005 to 2012, and three other tertiary centres in Singapore (Johns Hopkins-International Medical Centre, National University Hospital Singapore, and Onco-Care of Gleneagles Medical Centre). The patients in the comparison arm were treated from 2005 to 2009.

The researchers found favorable results when comparing the attenuated dosing regimen to the conventional dosing. They found 59% of the patients experienced severe side effects in the attenuated- dose group compared to 85% in the conventional group. There were significantly fewer reductions in dose delays (24% in the attenuated arm vs 58% in the conventional arm), and 35% rather than 70% of patients required dose reduction during their course of treatment. The median overall survival (OS) rate was 27.4 months for the conventional group compared to 21.8 months among patients receiving the attenuated dosage.

Dr. Tan said the results from this study are an affirmation that this approach is preferred for many Asian patients and will reap greater benefits. He noted that this study is important because it is prospective and it looked at patients in the real-world setting.

References:

• Medical News Today. (2015). NCCS pioneers new drug regimen which reduces toxicities for renal cancer patients.  
• Tan HS, Li H, Hong YW, et al. (2014). Efficacy and Safety of an Attenuated-Dose Sunitinib Regimen in Metastatic Renal Cell Carcinoma: Results From a Prospective Registry in Singapore. Clinical Genitourinary Cancer.