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Lower initial sorafenib doses did not adversely affect thyroid cancer outcomes
Lower starting doses of sorafenib do not appear to negatively affect outcomes in patients with advanced differentiated thyroid cancer and multiple comorbidities, which would preclude full dosage of the drug, according to recent findings.
“Our data suggest that treatment with sorafenib, when administered by experienced specialists outside of a clinical trial setting, resulted in similar efficacy and tolerability as previously reported in clinical trials,” Ramona Dadu, MD, from The University of Texas MD Anderson Cancer Center, said in a press release. “But, most importantly, we showed that the efficacy and tolerability of sorafenib in treatment-naive differentiated thyroid cancer patients does not appear to be negatively influenced by lower starting daily doses.”
In the retrospective study, researchers evaluated the medical records of 75 patients treated at MD Anderson Cancer Center from July 2005 to July 2013. All were adult patients with advanced, metastatic differentiated thyroid cancer who underwent a regimen of sorafenib (Nexavar, Bayer HealthCare) as first-line therapy. The researchers recorded relevant demographic and clinical data on the study participants.
The patients were subsequently grouped by sorafenib total starting dose. Group 1 (n=51) began a sorafenib regimen with a starting daily dose of 800 mg/day (administered as 400 mg twice a day), and group 2 (n=24) received starting doses of less than 800 mg/day. The outcomes were evaluated in terms of time to treatment failure, time to disease progression, and treatment discontinuation, dose reduction and interruption rates.
The researchers found that in group 1, the time to treatment failure was 10 months (95% CI, 5.6-14.3), and in group 2 the time to treatment failure was 8 months (95% CI, 3.4-12.5). Group 1 patients had a median OS of 56 months (95% CI, 30.6-81.3) and group 2 patients had an OS time of 30 months (95% CI, 16.1-43.8).
The rate of treatment discontinuation due to progression of disease was 79% in group 1 and 91% in group 2, and the rate treatment discontinuation due to toxicity was 21% in group 1 and 9% in group 2 (P=.304). Dose reductions occurred in 59% of patients in group 1 and 43% of patients in group 2 (P=.29), and rates of interruption were 65% in group 1 and 67% in group 2 (P=.908).
Herb Chen
Due to the unexpectedly similar rates of dose reduction, interruption and discontinuation between the two doses, the researchers concluded that the low starting dose of sorafenib should be reserved for cases of differentiated thyroid cancer in which full dosing is considered unsafe.
According to Herb Chen, MD, chief of surgery at the University of Wisconsin, these findings offer promise for treating differentiated thyroid cancer patients unable to tolerate full-dose sorafenib.
“While there is a trend toward a small difference in response rate between those starting on a lower dose vs. a standard dose, it is likely that these patients benefited from lower dose therapy,” Chen said in a press release. “This is noteworthy, as many patients cannot tolerate the standard dosing, and thus this study provides the first evidence that using the lower dosing regimen may be an effective strategy to treat thyroid cancer patients.”
Disclosure: One researcher reports a consulting/advisory relationship with Bayer, and another researcher reports a consulting/advisory relationship with Bayer-Onyx and a research funding relationship with Bayer.