A Study of Vemurafenib (RO5185426) in Participants With Metastatic or Unresectable Papillary Thyroid Cancer Positive for the BRAF V600 Mutation

An Open-Label, Multi-Center Phase II Study of the BRAF Inhibitor Vemurafenib in Patients With Metastatic or Unresectable Papillary Thyroid Cancer (PTC) Positive for the BRAF V600 Mutation and Resistant to Radioactive Iodine

This open-label, multi-center study will evaluate the safety and efficacy of Vemurafenib (RO5185426) in participants with metastatic or unresectable papillary thyroid cancer (PTC) positive for the BRAF V600 mutation and resistant to radioactive iodine therapy. Participants will receive vemurafenib 960 milligrams (mg) orally twice daily until progressive disease or unacceptable toxicity occurs.

Inclusion Criteria:

• Adult participants. >/= 18 years of age
• Histologically confirmed metastatic or unresectable papillary thyroid cancer for which standard curative or palliative measures do not exist or are no longer effective; participants whose tumors exhibit areas of "other histology" may be enrolled, provided the tumor histology remains predominantly papillary
• Positive for BRAF V600 mutation (Roche Cobas 4800 BRAF V600 Mutation Test)
• Radioactive Iodine resistant disease
• Prior therapy excluding (Cohort 1, TKI Naive) or including (Cohort 2, TKI Experienced) TKI
• Clinically relevant disease progression according to RECIST criteria within the prior 14 months
• Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
• Adequate hematological, renal and liver function

Exclusion Criteria:

• Histological diagnosis other than papillary PTC, including squamous cell variants of PTC or PTC with areas of squamous metaplasia
• Active or untreated central nervous system metastases
• History of or known carcinomatous meningitis
• Anticipated or ongoing administration of any anti-cancer therapies other than those administered in the study
• Active squamous cell skin cancer that has not been excised or adequately healed post excision
• Previous treatment with any agent that specifically and selectively targets the MEK or BRAF pathway
• Prior radiotherapy to the only measurable lesion
• Clinically relevant cardio-vascular disease or event within the prior 6 months