Severe Hepatotoxicity of Mithramycin Therapy Caused by Altered Expression of Hepatocellular Bile Transporters

Abstract

Mithramycin demonstrates preclinical anticancer activity, but its therapeutic dose is limited by the development of hepatotoxicity that remains poorly characterized. A pharmacogenomics characterization of mithramycin-induced transaminitis revealed that hepatotoxicity is associated with germline variants in genes involved in bile disposition: ABCB4 (multidrug resistance 3) rs2302387 and ABCB11 [bile salt export pump (BSEP)] rs4668115 reduce transporter expression (P , 0.05) and were associated with $grade 3 transaminitis developing 24 hours after the third infusion of mithramycin (25 mcg/kg, 6 hours/infusion, every day Â7, every 28 days; P , 0.0040). A similar relationship was observed in a pediatric cohort. We therefore undertook to characterize the mechanism of mithramycin-induced acute transaminitis. As mithramycin affects cellular response to bile acid treatment by altering the expression of multiple bile transporters (e.g., ABCB4, ABCB11, sodium/taurocholate cotransporting polypeptide, organic solute transporter a/b) in several cell lines [Huh7, HepaRG, HepaRG BSEP (2/2)] and primary human hepatocytes, we hypothesized that mithramycin inhibited bile-mediated activation of the farnesoid X receptor (FXR). FXR was downregulated in all hepatocyte cell lines and primary human hepatocytes (P , 0.0001), and mithramycin inhibited chenodeoxycholic acid-and GW4046-induced FXR-galactose-induced gene 4 luciferase reporter activity (P , 0.001). Mithramycin promoted glycochenodeoxycholic acid-induced cytotoxicity in ABCB11 (2/2) cells and increased the overall intracellular concentration of bile acids in primary human hepatocytes grown in sandwich culture (P , 0.01). Mithramycin is a FXR expression and FXR transactivation inhibitor that inhibits bile flow and potentiates bile-induced cellular toxicity, particularly in cells with low ABCB11 function. These results suggest that mithramycin causes hepatotoxicity through derangement of bile acid disposition; results also suggest that pharmacogenomic markers may be useful to identify patients who may tolerate higher mithramycin doses. SIGNIFICANCE STATEMENT The present study characterizes a novel mechanism of druginduced hepatotoxicity in which mithramycin not only alters farnesoid X receptor (FXR) and small heterodimer partner gene expression but also inhibits bile acid binding to FXR, resulting in deregulation of cellular bile homeostasis. Two novel singlenucleotide polymorphisms in bile flow transporters are associated with mithramycin-induced liver function test elevations, and the present results are the rationale for a genotype-directed clinical trial using mithramycin in patients with thoracic malignancies.

Thermodynamics of the Interaction between the Spike Protein of Severe Acute Respiratory Syndrome Coronavirus-2 and the Receptor of Human Angiotensin-Converting Enzyme 2. Effects of Possible Ligands

“…Tests of plicamycin, being already commercially and clinically approved, 60 to confirm its efficacy should be considered as a top priority, to be performed in vitro and in vivo. This should also include the assessment of its side effects such as hepatotoxicity, 61 which despite usually being transient and asymptomatic could limit its therapeutic use in certain patients with limited hepatic function. This is especially relevant in the context of emergency and urgency caused by the 2020 COVID-19 pandemic outbreak.…”

Thermodynamics of the interaction between the spike protein of severe acute respiratory syndrome- coronavirus-2 and the receptor of human angiotensin converting enzyme 2. Effects of possible ligands

“…Plicamycin (also known as mithramycin) being already commercially and clinically approved, 31 tests to confirm its efficacity should be considered as a top-most priority, to be performed in vitro and in vivo. This should also include the assessment of its side effects such as hepatotoxicity 32 , that in spite to be usually transient and asymptomatic, it could limit its therapeutic use in certain patients with limited hepatic function. Indeed, the potent RBD/ACE2 inhibition clearly demonstrated in the present work, and the vast knowledge of its pharmacology and pharmacokinetics, studied for decades, 33 known to be very active in lungs and esophagus, 34 makes this drug a very attractive opportunity to treat severe COVID-19 cases.…”

Mithramycin and Analogs for Overcoming Cisplatin Resistance in Ovarian Cancer

“…As a consequence, no efficacy was demonstrated. Notable transaminitis was seen within 72 h of treatment, reaching levels up to 500× the upper limit of normal, with resolution often taking 1–3 weeks [ 28 , 29 ]. Recent investigations suggested that the hepatotoxicity was related to the inhibition of farnesoid-X receptor signaling and germline variants in genes involved in bile acid flow and disposition (e.g., ABCB4 and ABCB11) [ 29 ].…”

“…Notable transaminitis was seen within 72 h of treatment, reaching levels up to 500× the upper limit of normal, with resolution often taking 1–3 weeks [ 28 , 29 ]. Recent investigations suggested that the hepatotoxicity was related to the inhibition of farnesoid-X receptor signaling and germline variants in genes involved in bile acid flow and disposition (e.g., ABCB4 and ABCB11) [ 29 ]. Interestingly, the associated hepatic injury was transient, rarely symptomatic, and did not require intervention; however, it significantly hampered the clinical utility of mithramycin [ 21 , 29 ].…”