EXAM

Medullary thyroid cancer arises from calcitonin-producing C cells and is driven by RET mutations in the hereditary and about half of sporadic cases. EXAM randomised 330 patients with documented progressive metastatic medullary thyroid cancer two to one to cabozantinib 140 mg daily or placebo, with progression-free survival as the primary endpoint.

Cabozantinib lengthened progression-free survival several-fold and produced objective responses in a substantial minority, regardless of RET mutation status, at the cost of diarrhoea, hand-foot syndrome, fatigue and hypertension. Overall survival was not significantly different in the whole population. It was approved in the United States in November 2012, following vandetanib (ZETA) as the second multikinase inhibitor for the disease; the selective RET inhibitors selpercatinib and pralsetinib have since displaced both for RET-mutant tumours.