Resistance to RET targeted therapy in Thyroid Cancer: Molecular basis and overcoming strategies.

Thyroid cancer is the most frequently diagnosed endocrine malignancy, with an increasing incidence over the last decades. The recent advances in understanding the molecular mechanisms underlying the carcinogenesis of thyroid cancer have led to a better therapeutic approach of these tumors. This has allowed the development and approval of several drugs during the past decade. The rearranged during transfection [RET] protooncogene encodes a transmembrane receptor tyrosine kinase, which is activated by chromosomal rearrangements or point mutations in multiple malignancies, including thyroid cancer. Selective RET inhibitors have proved their value in the treatment algorithm in molecularly selected patients with significantly high response rates and duration of response. Notwithstanding, there are patients who experiment rapid progression or tumor recurrence after an early response to those targeted therapies, which suggest the existence of primary and acquired mechanisms of resistance that have been largely unknown to date. In the present review, we attempt to provide a comprehensive analysis of the most relevant mechanisms of resistance to RET inhibitors which could help in the development of next generation MKI and RET inhibitors, along with combination strategies with different targeted therapies that could potentially overcome these resistances.

Surgical outcomes in the pheochromocytoma surgery. Results from the PHEO-RISK STUDY.

PURPOSE: To identify presurgical and surgical risk factors for postsurgical complications in the pheochromocytoma surgery. METHODS: A retrospective study of pheochromocytomas submitted to surgery in ten Spanish hospitals between 2011 and 2021. Postoperative complications were classified according to Clavien-Dindo scale. RESULTS: One hundred and sixty-two surgeries (159 patients) were included. Preoperative antihypertensive blockade was performed in 95.1% of the patients, being doxazosin in monotherapy (43.8%) the most frequent regimen. Patients pre-treated with doxazosin required intraoperative hypotensive treatment more frequently (49.4% vs 25.0%, P = 0.003) than patients treated with phenoxybenzamine, but no differences in the rate of intraoperative and postsurgical complications were observed. However, patients treated with phenoxybenzamine had a longer hospital stay (12.2 ± 11.16 vs 6.2 ± 6.82, P < 0.001) than those treated with doxazosin. Hypertension resolution was observed in 78.7% and biochemical cure in 96.6% of the patients. Thirty-one patients (19.1%) had postsurgical complications. Prolonged hypotension was the most common, in 9.9% (n = 16), followed by hypoglycaemia in six patients and acute renal failure in four patients. 13.0% of complications had a score ≥3 in the Clavien-Dindo scale. Postsurgical complications were more common in patients with diabetes, cerebrovascular disease, higher plasma glucose levels, higher urinary free metanephrine and norepinephrine, and with pheochromocytomas larger than 5 cm. CONCLUSION: Preoperative medical treatment and postsurgical monitoring of pheochromocytoma should be especially careful in patients with diabetes, cerebrovascular disease, higher levels of plasma glucose and urine free metanephrine and norepinephrine, and with pheochromocytomas >5 cm, due to the higher risk of postsurgical complications.