Efficacy of RET inhibitors in the management of advanced, RET mutated, pheochromocytoma. Pooled analysis of published cases with the addition of 2 new cases.

PURPOSE: Selective RET inhibitors are approved for treatment of RET-mutant lung and thyroid cancers. RET mutation is a druggable molecular driver of malignant pheochromocytomas/paragangliomas (PPGLs), but few data have been published regarding the efficacy of RET inhibitors in this clinical setting.

METHODS

We performed a pooled analysis of RET-mutated PPGLs treated with RET-inhibitors, including both literature published case reports and patients treated at our Institution.

RESULTS

Nine patients with advanced pheochromocytoma were collected (7 published cases and 2 patients followed in our department). Eight patients had metastatic disease and 6 of them were pretreated. Eight patients received selpercatinib and one patient received pralsetinib. All patients obtained clinical benefit, 5 of them reached a partial response, 2 a durable stable disease and 2 a complete response. Median progression free survival ranged between 5.5 – 56.3 months. Urinary catecholamine and metanephrine levels improved or normalized in 7 cases. The treatment was well tolerated but in 2 patients a dose reduction was needed, due to G3 adverse events.

CONCLUSION

RET inhibitors are efficacious in patients affected by PPGL with RET mutation or fusion. Based on these findings, these drugs represent a promising strategy and these data support the development of prospective clinical trials in this setting.