Anti VEGF-TKI Treatment and New Renal Adverse Events Not Reported in Phase III Trials.

Cabozantinib and lenvatinib have been approved for the treatment of progressive medullary thyroid cancer and radioiodine-resistant thyroid cancer, respectively. Both phase III trials of cabozantinib and lenvatinib reported that renal adverse events (AEs) rarely occurred. The cabozantinib phase III study reported no AEs related to renal toxicity. In the lenvatinib phase III trial grade 3 (CTCAE), proteinuria (urinary protein ≥3.5 g/24 h) was found in 10.0% of the lenvatinib and 0.0% of the placebo patients. We report a 23-year-old patient with metastatic medullary thyroid cancer who was enrolled in the phase III trial, comparing cabozantinib to placebo and a 67-year-old patient with metastatic, papillary thyroid carcinoma who was undergoing treatment with lenvatinib during his enrollment in the phase III trial. The first patient had a normal kidney function initially, but developed end-stage chronic kidney disease unexpectedly on cabozantinib and additional zoledronate infusion. Whereas the second patient suffered from a dramatic aggravation of his known mild chronic renal insufficiency (KDOQI stage 2) due to long standing hypertension and atherosclerosis during the treatment with lenvatinib. These severe AEs due to anti-VEGF tyrosine kinase inhibitor treatment were unknown so far. In conclusion, these 2 cases argue for increased awareness for the possibility of renal failure as a consequence of anti-VEFG treatment. Predisposing conditions like known mild chronic renal insufficiency with only mild proteinuria and with atherosclerosis or precipitating co-medications like zoledronate infusion need to be accounted for to prevent these severe AEs.