Skip to main content
OpenTrials
Active, Not Recruiting

NCT Number: NCT04211337

A Study of Selpercatinib (LY3527723) in Participants With RET-Mutant Medullary Thyroid Cancer

The reason for this study is to see if the study drug selpercatinib is safe and more effective compared to a standard treatment in participants with rearranged during transfection (RET)-mutant medullary thyroid cancer (MTC) that cannot be removed by surgery or has spread to other parts of the body. Participants who are assigned to the standard treatment and discontinue due to progressive disease have the option to potentially crossover to selpercatinib.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Notify Me

Key information

Age range

12 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Royal North Shore Hospital, St Leonards, New South Wales, Australia

Loading trial locations.

About this study

Adaptive sample size re-estimation will be performed at interim analysis. The sample size could be increased from approximately 250 to 400 depending on the results of interim analysis.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

  • At least 18 years of age (participants as young as 12 years of age will be allowed if permitted by local regulatory authorities).
  • Histologically or cytologically confirmed, unresectable, locally advanced and/or metastatic MTC and no prior history of treatment with kinase inhibitors for advanced/metastatic disease.
  • Radiographic progressive disease per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 at screening compared with a previous image taken within the prior 14 months as assessed by the BICR. Participants with measurable or non-measurable but evaluable disease are eligible; however, participants with non-measurable disease may not have disease limited to bone sites only.
  • A defined/acceptable RET gene alteration identified in a tumor, germline deoxyribonucleic acid (DNA) or blood sample.
  • Tumor tissue in sufficient quantity to allow for retrospective central analysis of RET mutation status
  • Eastern Cooperative Oncology Group performance status score of 0 to 2.
  • Adequate hematologic, hepatic, and renal function and electrolytes.
  • Men and women of childbearing potential must agree to use a highly effective contraceptive method during treatment with study drug and for 4 months following the last dose of study drug.
  • Ability to swallow capsules.

Exclusion criteria

  • An additional validated oncogenic driver in MTC if known that could cause resistance to selpercatinib treatment. Examples include, but are not limited to RAS or BRAF gene mutations and NTRK gene fusions.
  • Symptomatic central nervous system (CNS) 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, or prolongation of the QTcF >470 milliseconds on more than one electrocardiogram (ECG) during screening. Participants who are intended to receive vandetanib if randomized to the control arm are ineligible if QTcF is >450 milliseconds.
  • Active uncontrolled systemic bacterial, viral, or fungal infection or serious ongoing uncontrolled intercurrent illness.
  • Active hemorrhage 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.

Treatment and study plan

Selpercatinib

Drug

Administered orally

Other names: LY3527723, LOXO-292

Cabozantinib

Drug

Administered orally

Vandetanib

Drug

Administered orally

Primary outcomes

  1. Progression Free Survival (PFS) by Blinded Independent Central Review (BICR)

    Time frame: Baseline to Progressive Disease or Death from Any Cause, Whichever Occurs First, Up to 39 Months

    PFS is defined as the time from randomization until the occurrence of documented disease progression by the BICR, per Response Evaluation Criteria in Solid Tumors (RECIST 1.1) criteria, or death from any cause in the absence of BICR-documented progressive disease.

    Progressive Disease (PD) was at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions.

Secondary outcomes

  1. Treatment Failure-Free Survival (TFFS) by Blinded Independent Committee Review (BICR)

    Time frame: Baseline to Progressive Disease, Unacceptable Toxicity or Death from Any Cause Up to 39 Months

    TFFS by BICR is defined as the time from randomization to the first occurrence of:

    • documented radiographic disease progression per RECIST 1.1 as assessed by BICR; or
    • unacceptable toxicity leading to treatment discontinuation as assessed by the investigator.

    Progressive Disease (PD) was at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum on study and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions.

    To qualify as an event, the toxicity must be from an intolerable AE (defined as any study drug-related AE that meets protocol guidance for treatment discontinuation, with the exception of alopecia); or death (due to any cause).

  2. Overall Response Rate (ORR): Percentage of Participants With Complete Response (CR) or Partial Response (PR) by BICR

    Time frame: Baseline through Disease Progression or Death Up to 39 Months

    ORR is defined as the number of participants who achieved the best overall response (BOR) of CR or PR divided by the total number of participants randomized to each treatment arm. ORR per RECIST 1.1 as assessed by BICR.

  3. Duration of Response (DoR) by BICR

    Time frame: Date of CR or PR to Date of Disease Progression or Death Due to Any Cause Up to 39 Months

    DoR by BICR is defined as the time from the date that measurement criteria for complete response (CR) or partial response (PR) (whichever is first recorded) are first met by the BICR or investigator assessment, as applicable, until the first date that disease is recurrent or documented disease progression is observed, per RECIST 1.1 criteria, or the date of death from any cause in the absence of documented disease progression or recurrence. Progressive Disease (PD) was at least a 20% increase in the sum of the diameters of target lesions, with reference being the smallest sum and an absolute increase of at least 5 mm, or unequivocal progression of non-target lesions, or 1 or more new lesions.

  4. Overall Survival (OS)

    Time frame: Baseline

    Overall survival (OS) is defined as the time from randomization until death from any cause. If the participant is alive or lost to follow-up at the time of data analysis, OS data will be censored on the last date the participant is known to be alive.

  5. PFS2 by Investigator

    Time frame: Baseline

    Progression-free survival 2 (PFS2) is defined as the time from randomization to disease progression (radiographic or symptomatic progression as determined by the investigator) on the next line of treatment or death from any cause in the absence of observed disease progression. If the participant is alive at the cutoff for analysis, and disease progression has not been observed, PFS2 data will be censored on the latest date of last progression-free assessment or start of the next line of treatment.

  6. Comparative Tolerability: Number of Weeks With High Side Effect Bother Based Score of 3 or 4 on the Functional Assessment of Cancer Therapy Item GP5 (FACT-GP5)

    Time frame: Baseline to Progressive Disease, Unacceptable Toxicity or Death from Any Cause Up to 39 Months

    Comparative tolerability defined as a comparison of the proportion of time on treatment with high side effect bother as assessed by the FACT-GP5. The FACT-GP5 is a single question used to assess the overall bother of the treatment side effects. It is scored using a 5-point rating scale (0 = not at all; 1 = a little bit; 2 = somewhat; 3 = quite a bit; and 4 = very much), where lower scores reflect less bother from treatment side effects.

    Time with high side effect bother (i.e.) score of 3 or 4 is reported here and was derived as follows: cumulative amount of time, in weeks, during which a participant reports high side effect bother divided by the total duration of therapy (weeks), derived as (date of last study treatment dose - date of first study treatment dose + 1) divided by 7.

  7. The Concordance of the Local Lab and the Central Lab RET Results: Percentage of Participants With RET-Positive Specimens as Called by the Central Lab, Which is Also RET-Positive as Called by a Local Lab (Positive Percent Agreement)

    Time frame: Baseline

Sponsors and collaborators

Lead sponsor

Loxo Oncology, Inc.

Industry

Collaborators

  • Eli Lilly and Company

Registry information

Official study title

A Multicenter, Randomized, Open-label, Phase 3 Trial Comparing Selpercatinib to Physicians Choice of Cabozantinib or Vandetanib in Patients With Progressive, Advanced, Kinase Inhibitor Naïve, RET-Mutant Medullary Thyroid Cancer (LIBRETTO-531)

Acronym: LIBRETTO-531

Important dates

Study start
2020
Primary completion
2023
Study completion
2027
First posted
Dec 26, 2019
Registry last updated
Mar 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.