Anticancer Properties of the Antipsychotic Drug Chlorpromazine and Its Synergism With Temozolomide in Restraining Human Glioblastoma Proliferation In Vitro

Abstract

The extremely poor prognosis of patients affected by glioblastoma (GBM, grade IV glioma) prompts the search for new and more effective therapies. In this regard, drug repurposing or repositioning can represent a safe, swift, and inexpensive way to bring novel pharmacological approaches from bench to bedside. Chlorpromazine, a medication used since six decades for the therapy of psychiatric disorders, shows in vitro several features that make it eligible for repositioning in cancer therapy. Using six GBM cell lines, three of which growing as patient-derived neurospheres and displaying stem-like properties, we found that chlorpromazine was able to inhibit viability in an apoptosis-independent way, induce hyperdiploidy, reduce cloning efficiency as well as neurosphere formation and downregulate the expression of stemness genes in all these cell lines. Notably, chlorpromazine synergized with temozolomide, the first-line therapeutic in GBM patients, in hindering GBM cell viability, and both drugs strongly cooperated in reducing cloning efficiency and inducing cell death in vitro for all the GBM cell lines assayed. These results prompted us to start a Phase II clinical trial on GBM patients (EudraCT # 2019-001988-75; ClinicalTrials.gov Identifier: NCT04224441) by adding chlorpromazine to temozolomide in the adjuvant phase of the standard first-line therapeutic protocol.

Chlorpromazine Induces Cytotoxic Autophagy in Glioblastoma Cells via Endoplasmic Reticulum Stress and Unfolded Protein Response

“…Besides its well-known clinical e cacy in the treatment of psychiatric disorders, several recent reports depict CPZ as a multifaceted drug that is gaining increasing relevance in oncology, being able to interfere, beyond DRD2 at the synaptic level, with several cancer-related cellular factors [16,17]. In this work, we identi ed via ABPP + MS several cellular proteins involved in ER stress and UPR as possible targets of CPZ, due to the ability of this compound to modify their a nity toward ATP and thus, conceivably, their function.…”

“…Fluorescence microscopy con rmed the presence of abnormal nuclei, suggestive of the ability of CPZ to induce aberrant mitotic segregation. Under the same conditions, RPE-1 non-cancer cells showed neither hyperploidy nor aberrant mitosis hallmarks [17]. With the aim to validate those results, we performed an immuno uorescence analysis to detect nuclear aberrations in anchorage-dependent GBM cells, as well as in the neurospheres.…”

“…All GBM cell lines and RPE-1 cells were treated with an amount of CPZ corresponding to their respective IC30 dose (Table S1) for 24 hours, while control samples were treated with the same nal concentration of solvent (phosphate-buffered saline [PBS]). RNA extraction and ER stress gene expression were performed as previously described [17]. RT-PCR analyses were quanti ed using the 2 −∆∆ CT method.…”

“…More recently, this drug has also been described as active in vitro toward several biological features, hindering the survival capabilities of cancer cells, especially those of GBM [7][8][9][10][11][12][13][14][15][16]. Interestingly, CPZ synergizes with TMZ in reducing GBM cell viability, while both drugs cooperate in diminishing cloning e ciency and inducing cell death [17]. Our group is currently involved in exploring the molecular and cellular bases of a possible anticancer effect of CPZ in GBM, exploring the ability of this compound in inhibiting cell viability in an apoptosis-independent manner, inducing hyperdiploidy, reducing cloning e ciency and downregulating the expression of stemness genes in either anchorage-dependent GBM cells or neurospheres in vitro.…”

An Alternative Pipeline for Glioblastoma Therapeutics: A Systematic Review of Drug Repurposing in Glioblastoma

“…While several drugs targeting GSCs have been mentioned, certain agents were identified specifically because of their propensity to target GSCs. Chlorpromazine is one such agent, an antipsychotic that was shown to decrease stemness markers and neurosphere formation [178]. Nicardipine, a calcium channel blocker used for hypertension, was shown to promote apoptosis and enhance the toxic effect of TMZ against patient-derived GSCs [179].…”