Weekly Paclitaxel Safe, Well-Tolerated in Anaplastic Thyroid Carcinoma

Weekly paclitaxel is safe and well-tolerated among patients with anaplastic thyroid carcinoma (ATC), a notoriously aggressive malignancy, according to a poster presentation by researchers from the Prospective Clinical Study Committee of the Anaplastic Thyroid Carcinoma Research Consortium of Japan (ATCCJ), in Tokyo. They presented their findings at the 15th International Thyroid Congress (ITC) and 85th Annual Meeting of the American Thyroid Association (ATA) in Lake Buena Vista, Florida.

“We have demonstrated an objective outcome of standardized chemotherapeutic treatment in patients with ATC for the first time in the world,” reported authors led by Naoyoshi Onoda, MD, PhD, of the department of surgical oncology at Osaka City University. “Observed overall survival seemed better compared to that [previously] reported. Remarkable survival benefit was shown in stage IVB patients.”

ATC is difficult to manage due to its resistance to multimodality treatment efforts. For newly diagnosed patients, median survival time is less than 6 months because of the aggressive progression and invasiveness of ATC tumors.

The evidence base for ATC management has been largely limited to “retrospective accumulations of clinical experiences,” the coauthors noted. So in 2009, they established the ATCCJ to conduct a prospective, nationwide, open-label, single-arm clinical study to assess the feasibility, safety, and efficacy of weekly paclitaxel (80 mg/m²) for these patients. Between 2012 and March 2014, the study enrolled 71 patients from 14 centers. Of these, 56 patients (40 of whom were female) were deemed eligible for analysis. The median age of these patients was 71.3 years (range, 47–84). The IVA:B:C:X stage ratio was 10:18:24:4.

Of the 56 enrolled patients, 43 died of their disease, 1 was lost to follow-up, and another died in an accident, leaving 11 patients still alive at the time of the data cut-off, the authors reported.

“Median overall survival was estimated at 227 days (95% confidence interval [CI], 148.2–305.8),” they reported. “The objective response rate and the clinical benefit rate were 23.1% and 79.5%, respectively. The median time to progression was estimated as 47 days.”

Paclitaxel efficacy was evaluable in 39 patients, with no patients experiencing complete responses, 9 experiencing partial responses, 22 patients with stable disease. Progressive disease was recorded for 8 patients.

Grade 3 adverse events (AEs) occurred in 28.6% of the patients, but no severe AEs or treatment-related deaths were reported. Nearly all patients (98.2%) had treatment-related AEs of any grade, most frequently anemia (76.8%, all grades; grade ≥ 3 in 5.4% of patients).

While response rates were “far from satisfactory, weekly paclitaxel could be a feasible standardized chemotherapeutic regimen for ATC,” the coauthors concluded.

Combination of paclitaxel therapy followed by surgery might be a promising strategy, they noted. Of 14 patients who underwent surgical resection of the primary lesion after chemotherapy, complete resections were reported for 9 patients, and partial resections for the other 5. “These patients survived from 112 to 788 (median 365) days,” the coauthors reported.