LIBRETTO-531; NCT04211337

Medullary Thyroid Cancer

RET Inhibitor

A Multicenter, Randomized, Open-Label, Phase 3 Trial Comparing Selpercatinib to Physician’s Choice of Cabozantinib or Vandetanib in Patients With Progressive, Advanced, Kinase Inhibitor-Naïve, RET-Mutant Medullary Thyroid Cancer*

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Key Inclusion Criteria
  • Patients ≥12 years of age
  • Unresectable, locally advanced and/or metastatic medullary thyroid cancer (MTC) and no prior treatment with kinase inhibitors for advanced/metastatic disease
  • Radiographic progressive, evaluable disease at screening
  • A defined RET gene alteration identified in a tumor, germline DNA, or blood sample
    • Tumor tissue in sufficient quantity to allow for retrospective central analysis of RET mutation status
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
  • Adequate organ function
  • Patients with reproductive potential must use a highly effective contraceptive method for the duration of treatment and for 4 months after
  • Able to swallow capsules
Key Exclusion Criteria
  • An additional validated oncogenic driver in MTC, if known, that could cause resistance to selpercatinib treatment
  • Symptomatic central nervous system metastases, leptomeningeal carcinomatosis, or untreated spinal cord compression
  • Clinically significant active cardiovascular disease or history of myocardial infarction within 6 months
  • History of torsades de pointes
  • Prolongation of the QTc interval of >470 ms using Fridericia’s formula on more than one electrocardiogram during screening
    • Participants intended to receive vandetanib if QTc is >450 ms
  • Active bacterial, viral, or fungal infection, or serious uncontrolled and ongoing illness
  • Active or at significant risk for hemorrhage
  • Other malignancy unless nonmelanoma skin cancer, carcinoma in situ, or malignancy diagnosed ≥2 years previously and not currently active
    • Participants with multiple endocrine neoplasia type 2 (MEN2) associated pheochromocytoma may be eligible
This clinical trial is being conducted globally.
Selpercatinib 160 mg is administered PO BID.
Cabozantinib 140 mg is administered PO QD.
Vandetanib 300 mg is administered PO QD.
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The safety and efficacy of the agents under investigation have not been established. There is no guarantee that the agents will receive regulatory approval and become commercially available for the uses being investigated.