Sunitinib survival benefits still realized in late responders
medwireNews: Patients with metastatic renal cell carcinoma (mRCC) who fail to respond to sunitinib within 12 weeks should not be prematurely switched to an alternative treatment, say researchers who found late responders still have potential for prolonged survival.
“Lack of early response should not be considered an indication of treatment failure and therapy should not be prematurely switched for reasons other than disease progression or unmanageable toxicity,” say the study authors, led by Robert Motzer (Memorial Sloan-Kettering Cancer Center, New York, USA).
Of 1059 RCC patients participating in six trials of sunitinib, 398 (38%) had a confirmed objective response, including 12 with a complete response. The median time to tumor response was 10.6 weeks.
The 39% of patients who responded to treatment after 12 weeks (late response) had a significantly longer median progression-free survival (PFS) than the remaining patients who responded within 12 weeks ( early response), at 20.2 months versus 13.8 months. The median overall survival (OS) was also longer, at 40.8 months versus 37.8 months, but not significantly so.
“This apparent advantage for late responders was possibly the result of an implicit bias resulting from longer duration of therapy before progression,” the team notes in the European Journal of Cancer.
Other efficacy measures were largely similar between the two groups, including a similar median duration of response, as were most baseline patient characteristics, except for early responders being significantly younger, having a shorter interval since initial diagnosis, and having more lung metastases. The two groups also had a similar rate of treatment discontinuation because of an adverse event.
As expected, responders had a significantly longer PFS and OS than nonresponders, at a median of 16.3 months versus 5.3 months and 40.1 months versus 14.5 months, respectively. And overall response was predicted by favorable pretreatment prognostic factors. These included better Eastern Cooperative Oncology Group performance status, favorable Memorial Sloan-Kettering Cancer Center risk status, higher rates of prior nephrectomy, fewer bone metastases, and a longer interval since initial diagnosis.
Irrespective of the patient’s treatment duration or dose, tumor response to sunitinib independently predicted survival.
“These analyses demonstrate the robust and durable response possible with sunitinib treatment in mRCC and the subsequent potential for prolonged survival predicted by response, regardless of its timing,” the team reports.
“These findings have important implications for clinicians regarding expectations of treatment with sunitinib in order to optimise clinical benefit for their patients.”
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By Lucy Piper, Senior medwireNews Reporter