Vandetanib and cabozantinib are “effective treatment options” in most patients with medullary thyroid cancer (MTC), according to researchers who conducted a real-world analysis of the drugs.
The retrospective analysis, published in Thyroid, included patients with metastatic or locally advanced MTC who received treatment with one or both of the tyrosine kinase inhibitors (TKIs).
The researchers analyzed data on 48 patients (33 men and 15 women) from 4 tertiary medical centers in Germany. The patients’ median age at diagnosis was 46 years (range, 15-80 years), and 13% of them had a known germline RET mutation.
The median follow-up from the start of TKI treatment was 25 months (range, 0-146 months). The median duration of treatment was 17 months with vandetanib and 9 months with cabozantinib.
There were 47 patients who received vandetanib, 41 as first-line treatment and 6 as second-line treatment. There were 23 patients who received cabozantinib, 7 as first-line treatment and 16 as second-line treatment. Patients who received both TKIs were considered twice in the analysis.
There were no complete responses with either TKI.
The partial response rate was 26% in the vandetanib group overall, 24% with first-line vandetanib, and 33% with second-line vandetanib. The proportion of patients who had stable disease for at least 24 weeks was 34%, 39%, and 0%, respectively.
The partial response rate was 22% in the cabozantinib group overall, 0% with first-line cabozantinib, and 31% with second-line cabozantinib. The proportion of patients who had stable disease for at least 24 weeks was 13%, 43%, and 0%, respectively.
The median progression-free survival was 17 months with vandetanib and 4 months with cabozantinib. The median overall survival (OS) was 53 months and 24 months, respectively.
With vandetanib, the OS rate was 98% at 6 months and 86% at 12 months. With cabozantinib, the OS rates were 78% and 70%, respectively.
The most common treatment-emergent adverse events (TEAEs) in vandetanib-treated patients were diarrhea (40%), skin rash (38%), and fatigue (28%). The most common TEAEs in cabozantinib-treated patients were diarrhea (57%), loss of appetite/weight loss (56%), and fatigue (39%).
The rate of treatment discontinuation due to TEAEs was 19% in the vandetanib group and 52% in the cabozantinib group.
“These results emphasize that vandetanib and cabozantinib are effective drugs in MTC patients with an aggressive course of disease as first- and second-line treatments,” the study authors concluded.
“We hypothesize that the poorer prognosis of cabozantinib-treated patients in our retrospective analysis is most likely due to its use as second-line treatment after treatment failure on vandetanib. However, different degrees of efficacy of the two drugs are possible.”
Disclosures: This research was supported, in part, by Bayer and Eisai. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Koehler VF, Adam P, Frank-Raue K, et al. Real-world efficacy and safety of cabozantinib and vandetanib in advanced medullary thyroid cancer. Thyroid. 2021;31(3):459-469. doi:10.1089/thy.2020.0206