Lipoprotein-free mitotane exerts high cytotoxic activity in adrenocortical carcinoma

International audienceContext: Mitotane (o,p’-DDD), the only approved drug for advanced adrenocortical carcinoma (ACC), is a lipophilic agent that accumulates into circulating lipoprotein fractions and high lipid-containing tissues. Objective: The aim of our study was to evaluate the in vivo and in vitro biological implication of serum lipoproteins on pharmacological action of mitotane. Distribution and concentration of mitotane were studied in plasma and adrenal tissue samples from mitotane-treated patients. The impact of lipoprotein-bound or free (LP-F) mitotane was analyzed on proliferation and apoptosis of human adrenocortical H295R cells. A retrospective study of ACC patients treated or not with statins was also performed.Results: o,p’-DDD distribution among VLDL, LDL, HDL and lipoprotein-free (LP-F) fractions obtained after ultracentrifugation of 23 plasmas of mitotane-treated patients was widely distributed in each subfraction. A positive correlation was observed between mitotane levels in plasma and in LDL, HDL but also LP-F compartment. Intra-tumor o,p’-DDD concentrations in 5 ACC samples of mitotane-treated patients were found independent of cholesterol transporter expression, scavenger receptors (SrB1) and LDL-Receptors. In vitro studies showed significant higher anti-proliferative and pro-apoptotic effects and higher cell and mitochondrial uptake of mitotane when H295R cells were grown in LP-F medium. Finally, retrospective study of an ACC cohort of 26 mitotane-treated patients revealed that statin therapy was significantly associated with a higher rate of tumor control.Conclusions: Altogether, our in vitro and in vivo studies provided compelling evidence for a greater efficacy of lipoprotein-free mitotane. ACC patients may thus benefit from therapeutic strategies that aim to increase LP-F mitotane fraction

The Lack of Antitumor Effects of o,p'DDA Excludes Its Role as an Active Metabolite of Mitotane for Adrenocortical Carcinoma Treatment.: o,p'DDA is not an active metabolite of mitotane

International audience: Mitotane (o,p'DDD) is the most effective treatment of advanced adrenocortical carcinoma (ACC) but its mechanism of action remains unknown. Previous studies suggested that o,p'DDA may represent the active metabolite of mitotane. We aimed at reevaluating the potential role and pharmacological effects of o,p'DDA. Functional consequences of o,p'DDA exposure were studied on proliferation, steroidogenesis, and mitochondrial respiratory chain in human H295R and SW13 adrenocortical cells. Mitotane and its metabolites were quantified using high-performance liquid chromatography combined to an ultraviolet detection in these cells treated with o,p'DDD or o,p'DDA and in human adrenal tissues. Dose-response curves up to 300 μM showed that, as opposed to o,p'DDD, o,p'DDA did not inhibit cell proliferation nor alter respiratory chain complex IV activity, gene expression nor induce mitochondrial biogenesis, oxidative stress, or apoptosis. However, whereas mitotane drastically decreased expression of genes involved in steroidogenesis, o,p'DDA slightly reduced expression of some steroidogenic enzymes and exerts weak anti-secretory effects only at high doses. While o,p'DDD concentration was significantly reduced by 40 % in H295R cell supernatants after 48 h incubation, o,p'DDA levels remained unchanged suggesting that o,p'DDA was not efficiently transported into the cells. o,p'DDA was not detected in cell homogenates or supernatants after 48 h exposure to o,p'DDD, consistent with the absence of o,p'DDA production in these models. Finally, unlike o'p'DDD, we found that o,p'DDA content was undetectable in two ACC and one normal adrenal gland of mitotane-treated patients, suggesting a lack of cellular uptake and in situ production. Our results demonstrate that o,p'DDD, but not o,p'DDA, induces functional alterations in adrenal cells

Systemic short chain fatty acids limit antitumor effect of CTLA-4 blockade in hosts with cancer

International audienceGut microbiota composition influences the clinical benefit of immune checkpoints in patients with advanced cancer but mechanisms underlying this relationship remain unclear. Molecular mechanism whereby gut microbiota influences immune responses is mainly assigned to gut microbial metabolites. Short-chain fatty acids (SCFA) are produced in large amounts in the colon through bacterial fermentation of dietary fiber. We evaluate in mice and in patients treated with anti-CTLA-4 blocking mAbs whether SCFA levels is related to clinical outcome. High blood butyrate and propionate levels are associated with resistance to CTLA-4 blockade and higher proportion of Treg cells. In mice, butyrate restrains anti-CTLA-4-induced up-regulation of CD80/CD86 on dendritic cells and ICOS on T cells, accumulation of tumor-specific T cells and memory T cells. In patients, high blood butyrate levels moderate ipilimumab-induced accumulation of memory and ICOS + CD4 + T cells and IL-2 impregnation. Altogether, these results suggest that SCFA limits anti-CTLA-4 activity