Median overall survival better with combination therapy vs. chemotherapy alone for anaplastic thyroid cancer

International Thyroid Congress

PARIS — Patients with anaplastic thyroid cancer who received the vascular-disrupting agent fosbretabulin besides carboplatin and paclitaxel had a median overall survival of 5.1 months, which bested the 4.1 months observed with patients who received chemotherapy alone and represented a 29% reduction in mortality risk with combination therapy, according to results of the phase 2/3 FACT trial presented here at the International Thyroid Congress.

In addition, almost half (48%) of patients with anaplastic thyroid cancer who were treated with fosbretabulin plus carboplatin and paclitaxel were alive at 6 months compared with 37% of patients treated with chemotherapy alone. At 1 year, the number of patients alive was nearly doubled with combination therapy vs. chemotherapy alone (23% vs. 9%).

The randomized, controlled, phase 2/3 FACT trial examined the addition of fosbretabulin tromethamine (Zybrestat, Oxigene), also known as CA4P, to carboplatin and paclitaxel in patients with histologically confirmed anaplastic thyroid cancer. A total of 80 patients were included, fewer than the initially planned 180 patients, due to slow enrollment.

Researchers randomly assigned 55 patients to weekly fosbretabulin plus chemotherapy on day 2 of treatment for 3 weeks, and 25 patients to chemotherapy alone for 3 weeks. After six cycles, patients assigned fosbretabulin could elect to continue treatment; maintenance therapy continued until disease progression.

According to the results:

In patients aged 60 years and younger, median overall survival was 10.9 months with combination therapy vs. 3.1 months with chemotherapy alone (HR=0.38; 95% CI, 0.16-0.88).
In patients with stage IV disease, median overall survival was 5.7 months with combination therapy vs. 3.9 months with chemotherapy alone (HR=0.63; 95% CI, 0.34-1.15).
In patients with tumors of more than 6 cm, median overall survival was 5.7 months with combination therapy vs. 3.9 months with chemotherapy alone (HR=0.51; 95% CI, 0.22-1.19).

Neutropenia, transient hypertension and tumor pain were the most common adverse events reported with combination therapy.

Fosbretabulin received orphan drug designation for the treatment of anaplastic thyroid cancer, medullary thyroid cancer and stage IV papillary or follicular thyroid cancer. The drug is one of a novel class of small-molecule drug candidates that selectively targets and collapses tumor vasculature.

Additional FACT trial data are expected soon, including additional follow-up, subgroup analyses, and safety and efficacy data in additional cancer indications, such as advanced non–small cell lung cancer. – by Katie Kalvaitis

For more information:

Balkissoon J. OC-024. Presented at: the 14th International Thyroid Congress; Sept. 11-16, 2010; Paris.

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