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Vandetanib showed promise in treating advanced thyroid cancer
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The once-daily oral cancer drug vandetanib showed evidence of improved PFS in patients with locally advanced or metastatic differentiated thyroid cancer, according to results of a phase 2 trial.
Differentiated thyroid cancer accounts for approximately 90% of all cases of thyroid cancer, and no effective standard treatment exists for it, according to background information in the study.
Martin J. Schlumberger, MD, of the Institut Gustave Roussy at Universitè Paris-Sud in Villejuif, France, and colleagues evaluated the efficacy of vandetanib (Caprelsa, AstraZeneca), a tyrosine kinase inhibitor of three proteins that promotes the growth of thyroid cancer — RET, VEGF receptor and EGFR.
In a randomized, double blind trial, researchers at 16 European medical centers randomly assigned 145 patients with locally advanced metastatic differential thyroid cancer to vandetanib 300 mg daily (n=72) or placebo (n=73).
Researchers enrolled patients aged at least 18 years between Sept. 28, 2007, and Oct. 16, 2008.
According to study results, 52 patients in the vandetanib group and 61 patients in the placebo group progressed by data cutoff.
Forty patients died — 19 in the vandetanib group and 21 in the placebo group.
OS did not differ between the treatment groups, according to the researchers.
Patients who received vandetanib demonstrated longer PFS than those who received a placebo (HR=0.63, 60% CI, 0.54-0.74; P=.008), researchers found.
The median PFS was 11.1 months (95% CI, 7.7-14.0) for the vandetanib group and 5.9 months for the placebo group (95% CI, 4.0-8.9). The improved PFS among patients assigned to vandetranib was confirmed by independent review (HR=0.49; 95% CI, 0.32-0.74; P=.0007), according to researchers.
Among patients assigned to vandetanib, median survival varied based on the type of thyroid cancer. Patients with papillary thyroid cancer demonstrated a median PFS of 16.2 months, while patients with follicular thyroid cancer or poorly differentiated carcinoma demonstrated a median PFS of 7.7 months, study results showed.
Grade 3 or worse adverse events occurred more frequently in the vandetanib group (53%) compared with the placebo group (19%).
The most common adverse events were QTc prolongation and diarrhea. Two treatment-related deaths occurred in the vandetanib group, and one death occurred in the placebo group.
“These results are potentially good news for patients with aggressive differentiated thyroid cancer who currently have few treatment options,” Schlumberger said in a press release. “The significant improvements in PFS and disease control rate vs. placebo suggest that vandetanib may be an effective treatment option for long-term stabilization of advanced differentiated thyroid cancer, particularly for patients with papillary thyroid cancer.”
Although the substantial improvement in PFS would benefit patients with advanced thyroid cancer, PFS still must be assessed in a randomized phase 3 trial, Schlumberger and colleagues concluded.
In an accompanying editorial, Keith C. Bible, MD, PhD, an associate professor of oncology at Mayo Clinic in Rochester, Minn., said the study provides additional evidence about the clinical activity of vandetanib in differentiated thyroid cancer but leaves the issue of its effect on OS unresolved.
More work is needed to better clarify which patients with differentiated thyroid cancer may derive the greatest benefits from kinase inhibitors, Bible said.
“Evidence continues to accumulate to suggest an apparent beneficial role for the use of kinase inhibitors in selected patients,” Bible wrote. “[This study] is an important step in the right direction. Additional studies examining the comparative efficacies of competing therapeutic approaches to differentiated thyroid cancer, especially in more precisely defined populations of patients, are sorely needed.”
Disclosure: The study was funded by AstraZeneca. The researchers report serving on advisory boards for, receiving lecture fees from and holding employment relationships with AstraZeneca, Bayer, Eisai, Exelixis, Genzyme and Roche.
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