title: The PI3Kδ inhibitor idelalisib suppresses liver and lung cellular respiration.
abstract: Idelalisib (an inhibitor of phosphatidylinositol-3-kinase-delta) is approved for treatment of B-cell malignancies, with a Boxed Warning concerning potentially fatal hepatic, lung, and intestinal toxicities. The mechanisms of these tissue-specific adverse events have yet to be elucidated. This in vitro study investigated whether these effects could be attributed, at least in part, to altered cellular bioenergetics. A phosphorescence analyzer was used to measure cellular mitochondrial O2 consumption (kc , µM O2 min(-1) mg(-1)) in C57BL/6 mouse organs in the presence of 10 µM idelalisib or dimethyl-sulfoxide. Idelalisib significantly reduced the rate of cellular respiration in liver and lung fragments by 20% and 27%, respectively. Respiration in intestinal, thymic, and kidney fragments was unaffected. Idelalisib did not alter respiratory chain activities in mitochondria isolated from the liver and did not induce hepatocyte death. Thus, the drug mildly lowers liver and lung cellular respiration, an effect that may contribute to toxicities observed in these organs.
authors.affiliation: Department of Pediatrics, UAE University Al-Ain, Abu Dhabi, United Arab Emirates.
authors.forename: Suleiman Al
authors.initials: SA
authors.lastname: Hammadi
authors.affiliation: Department of Pathology, UAE University Al-Ain, Abu Dhabi, United Arab Emirates.
authors.forename: Saeeda
authors.initials: S
authors.lastname: Almarzooqi
authors.affiliation: Department of Medicine, UAE University Al-Ain, Abu Dhabi, United Arab Emirates.
authors.forename: Hidaya Mohammed
authors.initials: HM
authors.lastname: Abdul-Kader
authors.affiliation: Department of Pathology, UAE University Al-Ain, Abu Dhabi, United Arab Emirates.
authors.forename: Dhanya
authors.initials: D
authors.lastname: Saraswathiamma
authors.affiliation: Department of Pediatrics, UAE University Al-Ain, Abu Dhabi, United Arab Emirates.
authors.forename: Abdul-Kader
authors.initials: AK
authors.lastname: Souid
keywords: Cellular bioenergetics; PI3K delta; PI3K inhibitors; cellular respiration; idelalisib; liver toxicity; lung toxicity; mitochondrial function; oxidative phosphorylation
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