We report the efficacy and safety of dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) combination therapy in BRAF V600E-mutated anaplastic thyroid cancer, a rare, aggressive, and highly lethal malignancy with poor patient outcomes and no systemic therapies with clinical benefit. MethodsIn this phase II, open-label trial, patients with predefined BRAF V600E-mutated malignancies received dabrafenib 150 mg twice daily and trametinib 2 mg once daily until unacceptable toxicity, disease progression, or death. The primary end point was investigator-assessed overall response rate. Secondary end points included duration of response, progression-free survival, overall survival, and safety. ResultsSixteen patients with BRAF V600E-mutated anaplastic thyroid cancer were evaluable (median follow-up, 47 weeks; range, 4 to 120 weeks). All patients had received prior radiation treatment and/or surgery, and six had received prior systemic therapy. The confirmed overall response rate was 69% (11 of 16; 95% CI, 41% to 89%), with seven ongoing responses. Median duration of response, progression-free survival, and overall survival were not reached as a result of a lack of events, with 12-month estimates of 90%, 79%, and 80%, respectively. The safety population was composed of 100 patients who were enrolled with seven rare tumor histologies. Common adverse events were fatigue (38%), pyrexia (37%), and nausea (35%). No new safety signals were detected. ConclusionDabrafenib plus trametinib is the first regimen demonstrated to have robust clinical activity in BRAF V600E-mutated anaplastic thyroid cancer and was well tolerated. These findings represent a meaningful therapeutic advance for this orphan disease.

Rationally designed anticancer agents that target cell-surface antigens or receptors represent a promising approach for treating cancer patients. However, antibodies that bind these targets are often, by themselves, non-cytotoxic. By attaching potent toxins we can dramatically improve the clinical utility of some anti-tumour antibodies. Here we describe the construction and clinical utility of several recombinant immunotoxins; each of which is composed of antibody Fv fragments fused to powerful bacterial toxins. Results from clinical trials indicate that recombinant immunotoxins and similar agents that are designed to combine antibody selectivity with toxin cell-killing potency will be useful additions to cancer therapy.