Palbociclib inhibits proliferation of human adrenocortical tumor cells.

Adrenocortical cancer (ACC) is a rare malignant tumor [1]. Pharmacological therapy is based on mitotane administered alone or in association with the EDP regimen (etoposide, doxorubicin, and cisplatin) [1]. However, the prognosis of ACC patients not amenable to surgery still remains poor and newer treatment strategies are needed [2]. Drugs targeting cell cycle could be a relevant new therapeutic approach for patients with advanced ACC [3]. Cell cycle is controlled by several key proteins, including CDKs (cyclin-dependent kinases), which are the target of recently discovered cell-cycle checkpoint inhibitors [4]. Palbociclib is a CDK4/6-inhibitor that is active against a broad range of tumors and has an acceptable toxicity, being neutropenia being the most relevant side effect [5]. This drug is actually approved in the management of locally advanced or metastatic breast cancer [6]. In this study, we investigated in vitro the effect of Palbociclib in NCI-H295R ACC cells and human ACC primary cultures.