Clinical Outcomes of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers
Authors' conclusion
RDT has the potential to restore RAI avidity and induce RECIST responses following 131I therapy in select patients with RAIR-DTC, particularly those with RAS-driven "follicular" phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups.
Study context
- Population
- Patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent redifferentiation therapy (RDT) (MEK, RET or ALK inhibitors alone, or BRAF-MEK inhibitors for 4 weeks), 2017–2022, Mayo Clinic
- Participants
- 33 patients
- Exposure
- Redifferentiated vs non-redifferentiated after RDT
- Redifferentiatedn = 17
- Non-redifferentiatedn = 12reference
- Outcome
- Restored RAI uptake following RDT
Methodological detailssingle-centre
- Single-centre
Main finding
As reported in the abstract
- Restored radioactive iodine (RAI) uptake, all patients
- 57.6%
- Redifferentiated, papillary thyroid cancers (PTC)
- 42.1% (8/19)
- Redifferentiated, IEFV-PTC
- 100% (4/4)
- Redifferentiated, follicular thyroid cancers (FTC)
- 100% (7/7)
- Redifferentiated, RAS mutant
- All (11/11)
- Redifferentiated, BRAF mutant
- 38.9% (7/18)
Observational data: associations, not effects.
Further findings
Best overall RECIST response of SD or non-complete response/non-progressive disease
Tumor shrinkage on drug(s) alone · 3 weeks
| Outcome | Redifferentiated | Non-redifferentiated |
|---|---|---|
| Additional tumor reduction after high-dose 131I · 6 months after RDT | median 20 % | — not stated in the abstract |
— not stated in the abstract
- Best overall RECIST response of SD or non-complete response/non-progressive disease: 13/17 and 8/12
Progression free survival (PFS), time to systemic therapy, time to any additional therapy
- No statistically significant differences between groups
Safety
Histologic transformation to anaplastic thyroid cancer and death
- Anaplastic transformation
- 6.1% (2/33)
- Died
- 15.1% (5/33)
- All had redifferentiated following RDT and received 131I
Original publication
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