Key Inclusion Criteria:

1. Signed informed consent
2. Male or female ≥ 18 years of age at time of informed consent
3. Histologically or cytologically confirmed diagnosis of advanced/metastatic differentiated thyroid carcinoma
4. Radioactive-iodine refractory disease
5. BRAF V600E mutation-positive tumor sample as per central laboratory result
6. Has progressed on at least 1 but not more than 2 prior VEGFR targeted therapies
7. Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2
8. At least one measurable lesion as defined by RECIST v1.1.

Key Exclusion Criteria:

1. Anaplastic or medullary carcinoma of the thyroid
2. Previous treatment with a BRAF inhibitor and/or a MEK inhibitor
3. Concomitant RET Fusion-Positive Thyroid Cancer
4. Treatment with any type of small molecule kinase inhibitor (including investigational kinase inhibitor) within 2 weeks before randomization
5. Treatment with any type of anticancer antibody (including investigational antibody) or systemic chemotherapy within 4 weeks before randomization
6. Treatment with radiation therapy for bone metastasis within 2 weeks or any other radiation therapy within 4 weeks before randomization
7. A history or current evidence/risk of retinal vein occlusion (RVO) or central serous retinopathy

Other inclusion/exclusion criteria may apply.