First-Line Pembrolizumab Plus Chemoradiotherapy Found to Be Ineffective in Anaplastic Thyroid Cancer
Pembrolizumab plus concurrent chemotherapy and radiation therapy was not effective among patients with anaplastic thyroid cancer (ATC), according to a small study presented at the 88th Annual Meeting of the American Thyroid Association in Washington, D.C.1
A previous study demonstrated that PD-1 and PD-L1 are highly expressed by ATC tumors, suggesting that treatment with anti–PD-1/PD-L1 therapies may be effective in this type of cancer. Anecdotal reports, however, suggested limited single-agent efficacy with pembrolizumab. The aim of this trial was to determine if the combination of pembrolizumab with chemotherapy and radiation therapy would prompt synergistic activity against ATC.
The investigator-initiated phase 2 trial included 3 patients who were treated with 200 mg of pembrolizumab every 3 weeks in addition to docetaxel and doxorubicin plus weekly intensity-modulated radiation therapy as a first-line treatment regimen in ATC. The primary end point was overall survival (OS).
Though the initial tumor response to pembrolizumab was favorable across all 3 patients, the OS for each of the 3 patients was less than 6 months following therapy initiation. One patient died of tumor progression, and the others died as a result of infection-related complications. The historical median OS was determined to be 6 months.
Because pembrolizumab was found to not be efficacious in thyroid cancer compared with historical controls — and as a result of the 2 unexpected deaths that occurred during the trial that were determined to be linked to complications outside of tumor progression — the Data Safety and Monitoring Board recommended early closure of the study, and the study was ultimately terminated. The researchers added that they had limited enthusiasm surrounding study reactivation.