On June 12, 2024, the Food and Drug Administration granted traditional approval to selpercatinib (Retevmo, Eli Lilly and Company) for adult and paediatric patients 2 years of age and older with advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine-refractory (if radioactive iodine is appropriate).

Selpercatinib received accelerated approval for this indication for patients 12 years of age and older in 2020.

Efficacy was evaluated in LIBRETTO-001 (NCT03157128), a multicenter, open-label, muti-cohort clinical trial in 65 patients with RET fusion-positive thyroid cancer who were radioactive iodine (RAI)-refractory (if RAI was an appropriate treatment option) and were systemic therapy naïve and patients who were previously treated, in separate cohorts.

The major efficacy outcome measures were overall response rate (ORR) and duration of response (DOR). The ORR was 85% (95% CI: 71%, 94%) in the 41 previously treated patients and 96% (95% CI: 79%, 100%) in the 24 systemic therapy naïve patients.

Median DOR was 26.7 months (95% CI: 12.1, not evaluable [NE]) in the previously treated patients and NE (95% CI: 42.8, NE) in the systemic therapy naïve patients.

Supportive evidence included ORR and DOR data from 10 paediatric and young adult patients with RET fusion-positive thyroid cancer treated in Study LIBRETTO-121 (J2G-OX-JZJJ; NCT03899792), an international, single-arm, multi-cohort clinical trial of selpercatinib in paediatric and young adult patients with advanced RET-altered solid tumours.

The ORR was 60% (95% CI: 26%, 88%), and 83% had an observed duration of response ≥ 12 months.

The most common adverse reactions (≥25%) were oedema, diarrhoea, fatigue, dry mouth, hypertension, abdominal pain, constipation, rash, nausea, and headache.

The most common Grade 3 or 4 laboratory abnormalities (≥5%) were decreased lymphocytes, increased alanine aminotransferase (ALT), increased aspartate aminotransferase (AST), decreased sodium, and decreased calcium.

The recommended selpercatinib dose for paediatric patients 2 to less than 12 years of age is based on body surface area. It is based on weight for patients 12 years of age and older. See the prescribing information for specific dosing information.

Source: FDA