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Mitotane

"A derivative of the insecticide DICHLORODIPHENYLDICHLOROETHANE that specifically inhibits cells of the adrenal cortex and their production of hormones. It is used to treat adrenocortical tumors and causes CNS damage, but no bone marrow depression." (MeSH 2013)

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Latest Research Publications

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Latest Research Publications

This list of publications is regularly updated (Source: PubMed).

Schmouchkovitch A, Herry H, Thuillier P, et al.
Oral and vulvo-vaginal lichenoid reactions due to mitotane (Lysodren): A case report.
Medicine (Baltimore). 2017; 96(2):e5075 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The purpose of pharmacovigilance (drug safety) is collection, detection, assessment, monitoring, and prevention of adverse effects with pharmaceutical products. It is meant to identify, characterize, prevent, or minimize actual or potential risks relating to medicinal products. To prevent these adverse effects and improve our practice, health professionals have a duty to report side effects to assess this risk and evaluate the benefit/risk requirements. Mitotane (Lysodren) is used for treating adrenocortical carcinoma. Currently, no side effects concerning oral and genital mucosa have been reported.
CASE SUMMARY: This case report is about a 50 years old woman. Six months after the initiation on mitotane treatment, she developed erosive lesions located on the oral and vaginal mucosa. These drug reactions were diagnosed as erosive lichen planus by the biopsy. This lichenoid lesions were resistant to the usual treatments, mitotane being at the time not replaceable.
CONCLUSION: This case describes an unreported adverse effect of mitotane, it is - to our knowledge - the 1st description of erosive lichenoid drug reaction due to Mitotane.

Maiter D, Bex M, Vroonen L, et al.
Efficacy and safety of mitotane in the treatment of adrenocortical carcinoma: A retrospective study in 34 Belgian patients.
Ann Endocrinol (Paris). 2016; 77(5):578-585 [PubMed] Related Publications
OBJECTIVES: Evaluation of patient characteristics and mitotane use in the treatment of adrenocortical carcinoma (ACC) over a 4-year period in Belgium.
MATERIAL AND METHODS: This was a multicentre retrospective review of the outcome of 34 patients treated with mitotane for ACC during the period [01/2008-12/2011] (12 diagnosed before and 22 diagnosed during the study period) and evaluated up to 06/2013.
RESULTS: Patient and tumour characteristics were consistent with those generally described for ACC. Mean age at diagnosis was 46.5 years, most patients were female (62%), had functioning ACC (65%) and advanced tumours (ENSAT stages III or IV: 82%). Therapeutic mitotane plasma levels (14-20 mg/L) were achieved at least once in 70% of the cohort, after a median of 4 months, and were maintained for more than 2 months in 61% of evaluable patients. Mitotane-related adverse effects were observed in 66% of patients, were never serious, and included gastrointestinal, neurological, neuropsychological, hormonal, dermatologic and metabolic effects. Most patients (88%) discontinued mitotane, mainly due to tumour progression. Multivariate analysis showed that ENSAT stage was a prognostic factor for overall (OS) and disease-free survival (DFS); OS was also influenced independently by achievement of therapeutic mitotane plasma levels for at least two consecutive months.
CONCLUSION: Patient and tumour characteristics were consistent with previously published data. OS and DFS were mostly influenced by ENSAT stage at diagnosis. Achieving therapeutic levels of mitotane for at least two consecutive months seemed to positively influence OS, but such levels were not reached or sustained in some patients.

El Ghorayeb N, Rondeau G, Latour M, et al.
Rapid and Complete Remission of Metastatic Adrenocortical Carcinoma Persisting 10 Years After Treatment With Mitotane Monotherapy: Case Report and Review of the Literature.
Medicine (Baltimore). 2016; 95(13):e3180 [PubMed] Free Access to Full Article Related Publications
Mitotane has been used for more than 5 decades as therapy for adrenocortical carcinoma (ACC). However its mechanism of action and the extent of tumor response remain incompletely understood. To date no cases of rapid and complete remission of metastatic ACC with mitotane monotherapy has been reported. A 52-year-old French Canadian man presented with metastatic disease 2 years following a right adrenalectomy for stage III nonsecreting ACC. He was started on mitotane which was well tolerated despite rapid escalation of the dose. The patient course was exceptional as he responded to mitotane monotherapy after only few months of treatment. Initiation of chemotherapy was not needed and he remained disease-free with good quality of life on low maintenance dose of mitotane during the following 10 years. A germline heterozygous TP53 exon 4 polymorphism c.215C>G (p. Pro72Arg) was found. Immunohistochemical stainings for IGF-2 and cytoplasmic β-catenin were positive. Advanced ACC is an aggressive disease with poor prognosis and the current therapeutic options remain limited. These findings suggest that mitotane is a good option for the treatment of metastatic ACC and might result in rapid complete remission in selected patients.

Postlewait LM, Ethun CG, Tran TB, et al.
Outcomes of Adjuvant Mitotane after Resection of Adrenocortical Carcinoma: A 13-Institution Study by the US Adrenocortical Carcinoma Group.
J Am Coll Surg. 2016; 222(4):480-90 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Current treatment guidelines recommend adjuvant mitotane after resection of adrenocortical carcinoma with high-risk features (eg, tumor rupture, positive margins, positive lymph nodes, high grade, elevated mitotic index, and advanced stage). Limited data exist on the outcomes associated with these practice guidelines.
STUDY DESIGN: Patients who underwent resection of adrenocortical carcinoma from 1993 to 2014 at the 13 academic institutions of the US Adrenocortical Carcinoma Group were included. Factors associated with mitotane administration were determined. Primary end points were recurrence-free survival (RFS) and overall survival (OS).
RESULTS: Of 207 patients, 88 (43%) received adjuvant mitotane. Receipt of mitotane was associated with hormonal secretion (58% vs 32%; p = 0.001), advanced TNM stage (stage IV: 42% vs 23%; p = 0.021), adjuvant chemotherapy (37% vs 5%; p < 0.001), and adjuvant radiation (17% vs 5%; p = 0.01), but was not associated with tumor rupture, margin status, or N-stage. Median follow-up was 44 months. Adjuvant mitotane was associated with decreased RFS (10.0 vs 27.9 months; p = 0.007) and OS (31.7 vs 58.9 months; p = 0.006). On multivariable analysis, mitotane was not independently associated with RFS or OS, and margin status, advanced TNM stage, and receipt of chemotherapy were associated with survival. After excluding all patients who received chemotherapy, adjuvant mitotane remained associated with decreased RFS and similar OS; multivariable analyses again showed no association with recurrence or survival. Stage-specific analyses in both cohorts revealed no association between adjuvant mitotane and improved RFS or OS.
CONCLUSIONS: When accounting for stage and adverse tumor and treatment-related factors, adjuvant mitotane after resection of adrenocortical carcinoma is not associated with improved RFS or OS. Current guidelines should be revisited and prospective trials are needed.

Xu Y, Dong B, Huang J, et al.
Sphingosine kinase 1 is overexpressed and promotes adrenocortical carcinoma progression.
Oncotarget. 2016; 7(3):3233-44 [PubMed] Free Access to Full Article Related Publications
Adrenocortical carcinoma (ACC) is a rare endocrine tumor with a very poor prognosis. Sphingosine kinase 1 (SphK1), an oncogenic kinase, has previously been found to be upregulated in various cancers. However, the role of the SphK1 in ACC has not been investigated. In this study, SphK1 mRNA and protein expression levels as well as clinicopathological significance were evaluated in ACC samples. In vitro siRNA knockdown of SphK1 in two ACC cell lines (H295R and SW13) was used to determine its effect on cellular proliferation and invasion. In addition, we further evaluated the effect of SphK1 antagonist fingolimod (FTY720) in ACC in vitro and in vivo, as a single agent or in combination with mitotane, and attempted to explore its anticarcinogenic mechanisms. Our results show a significant over-expression of SphK1 mRNA and protein expression in the carcinomas compared with adenomas (P < 0.01 for all comparisons). Functionally, knockdown of SphK1 gene expression in ACC cell lines significantly decreased cell proliferation and invasion. FTY720 could result in a decreased cell proliferation and induction of apoptosis, and the combination of mitotane and FTY720 resulted in a greater anti-proliferative effect over single agent treatment in SW13 cells. Furthermore, FTY720 could markedly inhibit tumor growth in ACC xenografts. SphK1 expression is functionally associated to cellular proliferation, apoptosis, invasion and mitotane sensitivity of ACC. Our data suggest that SphK1 might be a potential therapeutic target for the treatment of ACC.

Kroiss M, Plonné D, Kendl S, et al.
Association of mitotane with chylomicrons and serum lipoproteins: practical implications for treatment of adrenocortical carcinoma.
Eur J Endocrinol. 2016; 174(3):343-53 [PubMed] Related Publications
OBJECTIVE: Oral mitotane (o,p'-DDD) is a cornerstone of medical treatment for adrenocortical carcinoma (ACC).
AIM: Serum mitotane concentrations >14  mg/l are targeted for improved efficacy but not achieved in about half of patients. Here we aimed at a better understanding of intestinal absorption and lipoprotein association of mitotane and metabolites o,p'-dichlorodiphenylacetic acid (o,p'-DDA) and o,p'-dichlorodiphenyldichloroethane (o,p'-DDE).
DESIGN: Lipoproteins were isolated by ultracentrifugation from the chyle of a 29-year-old patient and serum from additional 14 ACC patients treated with mitotane. HPLC was applied for quantification of mitotane and metabolites. We assessed NCI-H295 cell viability, cortisol production, and expression of endoplasmic reticulum (ER) stress marker genes to study the functional consequences of mitotane binding to lipoproteins.
RESULTS: Chyle of the index patient contained 197  mg/ml mitotane, 53  mg/ml o,p'-DDA, and 51  mg/l o,p'-DDE. Of the total mitotane in serum, lipoprotein fractions contained 21.7±21.4% (VLDL), 1.9±0.8% (IDL), 8.9±5.5% (LDL1), 18.9±9.6% (LDL2), 10.1±4.0% (LDL3), and 26.3±13.0% (HDL2). Only 12.3±5.5% were in the lipoprotein-depleted fraction.
DISCUSSION: Mitotane content of lipoproteins directly correlated with their triglyceride and cholesterol content. O,p'-DDE was similarly distributed, but 87.9±4.2% of o,p'-DDA found in the HDL2 and lipoprotein-depleted fractions. Binding of mitotane to human lipoproteins blunted its anti-proliferative and anti-hormonal effects on NCI-H295 cells and reduced ER stress marker gene expression.
CONCLUSION: Mitotane absorption involves chylomicron binding. High concentrations of o,p'-DDA and o,p'-DDE in chyle suggest intestinal mitotane metabolism. In serum, the majority of mitotane is bound to lipoproteins. In vitro, lipoprotein binding inhibits activity of mitotane suggesting that lipoprotein-free mitotane is the therapeutically active fraction.

Sbiera S, Leich E, Liebisch G, et al.
Mitotane Inhibits Sterol-O-Acyl Transferase 1 Triggering Lipid-Mediated Endoplasmic Reticulum Stress and Apoptosis in Adrenocortical Carcinoma Cells.
Endocrinology. 2015; 156(11):3895-908 [PubMed] Related Publications
Adrenocortical carcinoma (ACC) is a rare malignancy that harbors a dismal prognosis in advanced stages. Mitotane is approved as an orphan drug for treatment of ACC and counteracts tumor growth and steroid hormone production. Despite serious adverse effects, mitotane has been clinically used for decades. Elucidation of its unknown molecular mechanism of action seems essential to develop better ACC therapies. Here, we set out to identify the molecular target of mitotane and altered downstream mechanisms by combining expression genomics and mass spectrometry technology in the NCI-H295 ACC model cell line. Pathway analyses of expression genomics data demonstrated activation of endoplasmic reticulum (ER) stress and profound alteration of lipid-related genes caused by mitotane treatment. ER stress marker CHOP was strongly induced and the two upstream ER stress signalling events XBP1-mRNA splicing and eukaryotic initiation factor 2 A (eIF2α) phosphorylation were activated by mitotane in NCI-H295 cells but to a much lesser extent in four nonsteroidogenic cell lines. Lipid mass spectrometry revealed mitotane-induced increase of free cholesterol, oxysterols, and fatty acids specifically in NCI-H295 cells as cause of ER stress. We demonstrate that mitotane is an inhibitor of sterol-O-acyl-transferase 1 (SOAT1) leading to accumulation of these toxic lipids. In ACC tissue samples we show variable SOAT1 expression correlating with the response to mitotane treatment. In conclusion, mitotane confers adrenal-specific cytotoxicity and down-regulates steroidogenesis by inhibition of SOAT1 leading to lipid-induced ER stress. Targeting of cancer-specific lipid metabolism opens new avenues for treatment of ACC and potentially other types of cancer.

Jebabli N, Gaïes E, Eljebari H, et al.
Contribution of Therapeutic Monitoring in the Assessment of Toxic Adverse Effects of Mitotane: a Case Report.
Therapie. 2015 Nov-Dec; 70(6):545-6 [PubMed] Related Publications
Mitotane provided serious side effects and low doses seemed to be tolerated. Determination of mitotane concentration in plasma is recommended. We report the case of toxic plasma levels with low doses of mitotane in a 47-year-old man with adrenocortical cancer.

Russo M, Scollo C, Pellegriti G, et al.
Mitotane treatment in patients with adrenocortical cancer causes central hypothyroidism.
Clin Endocrinol (Oxf). 2016; 84(4):614-9 [PubMed] Related Publications
INTRODUCTION: Mitotane, a steroidogenesis inhibitor with adrenolytic properties used to treat adrenocortical cancer (ACC), can affect thyroid function. A reduction of FT4 levels with normal FT3 and TSH has been described in these patients. Using an in vitro murine model, the secretory capacity of thyrotrophic cells has been shown to be inhibited by mitotane.
OBJECTIVE: To investigate the pathogenesis of thyroid abnormalities in mitotane-treated patients with ACC.
PATIENTS AND METHODS: In five female patients with ACC (median age 47; range 31-65) treated with mitotane (dosage 1·5 g/day; 1·0-3·0), we analysed the pattern of TSH and thyroid function index (FT4, FT3 and FT3/FT4 ratio) compared to an age- and gender-matched control group. The in vivo secretory activity of the thyrotrophic cells was evaluated using a standard TRH test (200 μg), and the response was compared to both a group of age-matched female controls (n = 10) and central hypothyroid patients (n = 10).
RESULTS: Basal TSH (median 1·54 mU/l; range 1·20-2·17) was normal and scattered around our median reference value, FT3 levels (median 3·80 pmol/l; 3·30-4·29) were normal but below the median reference value of 4·37 pmol/l and FT4 levels were below the normal range in all patients (median 8·40 pmol/l; 7·6-9·9). FT3/FT4 ratio was in the upper range in 4 patients and higher than normal in one patient. A blunted TSH response to TRH was observed in mitotane-treated patients. ΔTSH (absolute TSH response, peak TSH minus basal TSH) was 3·65 (range 3·53-5·26), 12·37 (range 7·55-19·97) and 1·32 mU/l (range 0·52-4·66) in mitotane-treated patients, controls and central hypothyroid patients, respectively. PRL secretion was normal.
CONCLUSIONS: Mitotane-treated patients with ACC showed low FT4, normal FT3 and TSH and impaired TSH response to TRH, characteristic of central hypothyroidism. Furthermore, the elevated FT3/FT4 ratio of these subjects reflects an enhanced T4 to T3 conversion rate, a compensatory mechanism characteristic of thyroid function changes observed in hypothyroid conditions. This finding thus confirms in vitro studies and may have a therapeutic implication for treatment with thyroid hormones, as suggested by current guidelines for this specific condition.

Hescot S, Seck A, Guerin M, et al.
Lipoprotein-Free Mitotane Exerts High Cytotoxic Activity in Adrenocortical Carcinoma.
J Clin Endocrinol Metab. 2015; 100(8):2890-8 [PubMed] Related Publications
CONTEXT: 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 effect of lipoprotein-bound or lipoprotein-free (LP-F) mitotane was analyzed on proliferation and apoptosis of human adrenocortical H295R cells. A retrospective study of patients with ACC treated or not with statins was also performed.
RESULTS: o,p'-DDD distribution among very low-density lipoprotein, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and LP-F fractions obtained after plasma ultracentrifugation of 23 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. Intratumor o,p'-DDD concentrations in five ACC samples of mitotane-treated patients were found to be independent of cholesterol transporter expression, scavenger receptors, and LDL receptors. In vitro studies showed significant higher antiproliferative and proapoptotic 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 LP-F mitotane. Patients with ACC may thus benefit from therapeutic strategies that aim to increase LP-F mitotane fraction.

Baudin E,
Adrenocortical carcinoma.
Endocrinol Metab Clin North Am. 2015; 44(2):411-34 [PubMed] Related Publications
Recent developments in the treatment of adrenocortical carcinoma (ACC) include diagnostic and prognostic risk stratification algorithms, increasing evidence of the impact of historical therapies on overall survival, and emerging targets from integrated epigenomic and genomic analyses. Advances include proper clinical and molecular characterization of all patients with ACC, standardization of proliferative index analyses, referral of these patients to large cancer referral centers at the time of first surgery, and development of new trials in patients with well-characterized ACC. Networking and progress in the molecular characterization of ACC constitute the basis for significant future therapeutic breakthroughs.

Theile D, Haefeli WE, Weiss J
Effects of adrenolytic mitotane on drug elimination pathways assessed in vitro.
Endocrine. 2015; 49(3):842-53 [PubMed] Related Publications
Mitotane (1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, o,p'-DDD) represents one of the most active drugs for the treatment of adrenocortical carcinoma. Its metabolites 1,1-(o,p'-dichlorodiphenyl) acetic acid (=o,p'-DDA) and 1,1-(o,p'-dichlorodiphenyl)-2,2 dichloroethene (=o,p'-DDE) partly contribute to its pharmacological effects. Because mitotane has a narrow therapeutic index and causes pharmacokinetic drug-drug interactions, knowledge about these compounds' effects on drug metabolizing and transporting proteins is crucial. Using quantitative real-time polymerase chain reaction, our study confirmed the strong inducing effects of o,p'-DDD on mRNA expression of cytochrome P450 3A4 (CYP3A4, 30-fold) and demonstrated that other enzymes and transporters are also induced (e.g., CYP1A2, 8.4-fold; ABCG2 (encoding breast resistance cancer protein, BCRP), 4.2-fold; ABCB1 (encoding P-glycoprotein, P-gp) 3.4-fold). P-gp induction was confirmed at the protein level. o,p'-DDE revealed a similar induction profile, however, with less potency and o,p'-DDA had only minor effects. Reporter gene assays clearly confirmed o,p'-DDD to be a PXR activator and for the first time demonstrated that o,p'-DDE and o,p'-DDA also activate PXR albeit with lower potency. Using isolated, recombinant CYP enzymes, o,p'-DDD and o,p'-DDE were shown to strongly inhibit CYP2C19 (IC50 = 0.05 and 0.09 µM). o,p'-DDA exhibited only minor inhibitory effects. In addition, o,p'-DDD, o,p'-DDE, and o,p'-DDA are demonstrated to be neither substrates nor inhibitors of BCRP or P-gp function. In summary, o,p'-DDD and o,p'-DDE might be potential perpetrators in pharmacokinetic drug-drug interactions through induction of drug-metabolizing enzymes or drug transporters and by potent inhibition of CYP2C19. In tumors over-expressing BCRP or P-gp, o,p'-DDD and its metabolites should retain their efficacy due to a lack of substrate characteristics.

Germano A, Rapa I, Volante M, et al.
RRM1 modulates mitotane activity in adrenal cancer cells interfering with its metabolization.
Mol Cell Endocrinol. 2015; 401:105-10 [PubMed] Related Publications
The anti-proliferative activity of mitotane (o,p'DDD) in adrenocortical cancer is mediated by its metabolites o,p'DDE and o,p'DDA. We previously demonstrated a functional link between ribonucleotide reductase M1(RRM1) expression and o,p'DDD activity, but the mechanism is unknown. In this study we assessed the impact of RRM1 on the bioavailability and cytotoxic activity of o,p'DDD, o,p'DDE and o,p'DDA in SW13 and H295R cells. In H295R cells, mitotane and its metabolites showed a similar cytotoxicity and RRM1 expression was not influenced by any drug. In SW13 cells, o,p'DDA only showed a cytotoxic activity and did not modify RRM1 expression, whereas the lack of sensitivity to o,p'DDE was associated to RRM1 gene up-modulation, as already demonstrated for o,p'DDD. RRM1 silencing in SW13 cells increased the intracellular transformation of mitotane into o,p'DDE and o,p'DDA. These data demonstrate that RRM1 gene interferes with mitotane metabolism in adrenocortical cancer cells, as a possible mechanisms of drug resistance.

Salenave S, Bernard V, Do Cao C, et al.
Ovarian macrocysts and gonadotrope-ovarian axis disruption in premenopausal women receiving mitotane for adrenocortical carcinoma or Cushing's disease.
Eur J Endocrinol. 2015; 172(2):141-9 [PubMed] Related Publications
CONTEXT: Mitotane is an adrenolytic and anticortisolic drug used in adrenocortical carcinoma (ACC), Cushing's disease (CD), and ectopic ACTH syndrome. Its effects on the ovaries are unknown.
OBJECTIVE: To evaluate the ovarian and gonadotrope effects of mitotane therapy in premenopausal women.
PATIENTS: We studied 21 premenopausal women (ACC: n=13; CD: n=8; median age 33 years, range 18-45 years) receiving mitotane at a median initial dose of 3 g/day (range 1.5-6 g/day).
METHODS: Gynecological history was collected and ovarian ultrasound was performed. Four women also underwent ovarian CT or magnetic resonance imaging. Serum gonadotropin, estradiol (E2), androgens, sex hormone-binding globulin (SHBG), and circulating mitotane levels were determined at diagnosis and during mitotane therapy.
RESULTS: In the women included, ovarian macrocysts (bilateral in 51%) were detected after a median 11 months (range: 3-36) of mitotane exposure. The median number of macrocysts per woman was two (range: 1-4) and the median diameter of the largest cysts was 50 mm (range: 26-90). Menstrual irregularities and/or pelvic pain were present in 15 out of 21 women at macrocyst diagnosis. In two women, the macrocysts were revealed by complications (ovarian torsion and hemorrhagic macrocyst rupture) that required surgery. Mitotane therapy was associated with a significant decrease in androstenedione and testosterone levels and a significant increase in LH levels. Serum FSH and E2 levels were also increased, and SHBG levels rose markedly.
CONCLUSIONS: Mitotane therapy causes significant morphological and ovarian/gonadotrope hormonal abnormalities in premenopausal women. Follicular thecal steroid synthesis appears to be specifically altered and the subsequent increase in gonadotropins might explain the development of macrocysts. The mechanisms underlying these adverse effects, whose exact prevalence in this population still needs to be determined, are discussed.

Campo MR, Lamacchia O, Farese A, et al.
Mitotane and Carney Complex: ten years follow-up of a low-dose mitotane regimen inducing a sustained correction of hypercortisolism.
Hormones (Athens). 2015 Apr-Jun; 14(2):300-4 [PubMed] Related Publications
OBJECTIVE: Primary pigmented nodular adrenocortical disease (PPNAD), an uncommon cause of Cushing's syndrome, is frequently associated with a wider clinical spectrum, the Carney complex (CC), a multiple endocrine neoplasia syndrome.
DESIGN: We evaluated a low-dose mitotane regimen for treating severe hypercortisolism in a 27-year-old woman with CC. She presented with severe hypercortisolism and a history of surgeries for breast ductal adenoma, atrial cardiac myxomas with cerebral and peripheral arterial embolism, and near-total thyroidectomy because of an oxyphilic adenoma. The patient refused further surgery for adrenalectomy.
RESULTS: During the first 7 months of mitotane (Lysodren, HRA Pharma, Paris, France), the daily oral dose was progressively increased from 0.5 to 4 g/day and then stopped because of the appearance of sustained signs of hypoadrenalism, that required a replacement therapy with 5 mg of prednisone o.d. A 10-month mitotane off-therapy follow-up was performed and when an increase in urine free cortisol (UFC) was noted, the mitotane regimen was restarted at lower doses (0.750-1 g/day). Serum morning cortisol levels and UFC were then maintained within the normal range, with plasma mitotane ranging between 2 and 4 mg/L. A sustained regression of Cushing's features without inducing hypoadrenalism was achieved, which still persists after 122 months of follow-up. Minimal initial gastric discomfort was the only side effect of which the patient complained and only during the first higher dose mitotane course.
CONCLUSIONS: Long-term administration of a low maintenance dose of mitotane may be suggested as treatment for hypercortisolism in CC patients who refuse or are at high risk for surgical adrenalectomy.

Tada H, Nohara A, Kawashiri MA, et al.
Marked transient hypercholesterolemia caused by low-dose mitotane as adjuvant chemotherapy for adrenocortical carcinoma.
J Atheroscler Thromb. 2014; 21(12):1326-9 [PubMed] Related Publications
We herein report a case of marked transient hypercholesterolemia in a man receiving low-dose mitotane as adjuvant chemotherapy for adrenocortical carcinoma.A 58-year-old man without any clinical symptoms or history of hypercholesterolemia was admitted to our hospital to treat an adrenocortical carcinoma detected on general screening using computed tomography. He reported no chest symptom and did not exhibit any established risk factors for coronary artery disease, such as diabetes, obesity, hypertension or relevant family history, with the exception of current smoking, on admission. A stress electrocardiogram showed negative findings. The left adrenal tumor as well as left kidney, spleen and distal portion of the pancreas were subsequently resected using radical surgery. The histopathological findings confirmed the preoperative diagnosis of adrenocortical carcinoma. After the operation, treatment with low-dose mitotane (1g/day) was introduced as adjuvant chemotherapy. Interestingly, the patient developed marked hyper-LDL cholesterolemia at a level equivalent to that of familial hypercholesterolemia (LDL cholesterol level ~ 300 mg/dL) following the introduction of mitotane, without evidence of primary or secondary hypercholesterolemia due to other causes. A coronary angiogram performed to assess the new-onset angina revealed three-vessel disease, which was later revascularized via percutaneous coronary intervention eight months after the start of mitotane therapy. The cholesterol level normalized with the suspension of mitotane. This case suggests that mitotane can cause severe hypercholesterolemia, potentially resulting in coronary atherosclerosis.

Kerkhofs TM, Derijks LJ, Ettaieb MH, et al.
Short-term variation in plasma mitotane levels confirms the importance of trough level monitoring.
Eur J Endocrinol. 2014; 171(6):677-83 [PubMed] Related Publications
OBJECTIVE: Mitotane is the drug of choice in patients with adrenocortical carcinoma. The anti-neoplastic effect is correlated with mitotane plasma levels, which render it crucial to reach and maintain the concentration above 14 mg/l. However, mitotane pharmacokinetics is poorly understood. The aim of this study was to investigate the variation in plasma mitotane levels during the day and the influence of a single morning dose.
DESIGN: A prospective case-control study was conducted to investigate the variation in plasma mitotane levels.
METHODS: Patients who had been treated for at least 24 weeks and had reached the therapeutic plasma level (14 mg/l) at least once were eligible. In the first group, mitotane levels were determined hourly for the duration of 8 h after administration of a single morning dose. In the second group, mitotane levels were assessed similarly without administration of a morning dose.
RESULTS: Ten patients were included in this study, and three patients participated in both groups. Median plasma level at baseline was 16.2 mg/l (range 11.3-23.3 mg/l) in the first group (n=7) and 17.0 mg/l (13.7-23.8) in the second group (n=6). Plasma levels displayed a median increase compared with baseline of 24% (range 6-42%) at t=4 after morning dose and a change of 13% (range -14 to 33%) at t=4 without morning dose (P=0.02).
CONCLUSION: A substantial increase in mitotane plasma levels was observed in steady-state patients within a period of 8 h after morning dosing. Without morning dose, mitotane curves showed a variable profile throughout the day. This implies that random sampling could yield incidentally high levels. For this reason, we recommend early-morning trough sampling as standard management in monitoring mitotane treatment.

Ronchi CL, Sbiera S, Volante M, et al.
CYP2W1 is highly expressed in adrenal glands and is positively associated with the response to mitotane in adrenocortical carcinoma.
PLoS One. 2014; 9(8):e105855 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Adrenocortical tumors comprise frequent adenomas (ACA) and rare carcinomas (ACC). Human cytochrome P450 2W1 (CYP2W1) is highly expressed in some cancers holding the potential to activate certain drugs into tumor cytotoxins.
OBJECTIVE: To investigate the CYP2W1 expression in adrenal samples and its relationship with clinical outcome in ACC.
MATERIAL AND METHODS: CYP2W1 expression was investigated by qRT-PCR in 13 normal adrenal glands, 32 ACA, 25 ACC, and 9 different non-adrenal normal tissue samples and by immunohistochemistry in 352 specimens (23 normal adrenal glands, 33 ACA, 239 ACC, 67 non-adrenal normal or neoplastic samples).
RESULTS: CYP2W1 mRNA expression was absent/low in normal non-adrenal tissues, but high in normal and neoplastic adrenal glands (all P<0.01 vs non-adrenal normal tissues). Accordingly, CYP2W1 immunoreactivity was absent/low (H-score 0-1) in 72% of non-adrenal normal tissues, but high (H-score 2-3) in 44% of non-adrenal cancers, in 65% of normal adrenal glands, in 62% of ACAs and in 50% of ACCs (all P<0.001 vs non-adrenal normal tissues), being significantly increased in steroid-secreting compared to non-secreting tumors. In ACC patients treated with mitotane only, high CYP2W1 immunoreactivity adjusted for ENSAT stage was associated with longer overall survival and time to progression (P<0.05 and P<0.01, respectively), and with a better response to therapy both as palliative (response/stable disease in 42% vs 6%, P<0.01) or adjuvant option (absence of disease recurrence in 69% vs 45%, P<0.01).
CONCLUSION: CYP2W1 is highly expressed in both normal and neoplastic adrenal glands making it a promising tool for targeted therapy in ACC. Furthermore, CYP2W1 may represent a new predictive marker for the response to mitotane treatment.

Gagliano T, Gentilin E, Benfini K, et al.
Mitotane enhances doxorubicin cytotoxic activity by inhibiting P-gp in human adrenocortical carcinoma cells.
Endocrine. 2014; 47(3):943-51 [PubMed] Related Publications
Mitotane is currently employed as adjuvant therapy as well as in the medical treatment of adrenocortical carcinoma (ACC), alone or in combination with chemotherapeutic agents. It was previously demonstrated that mitotane potentiates chemotherapeutic drugs cytotoxicity in cancer cells displaying chemoresistance due to P-glycoprotein (P-gp), an efflux pump involved in cancer multidrug resistance. The majority of ACC expresses high levels of P-gp and is highly chemoresistent. The aim of our study was to explore in vitro whether mitotane, at concentrations lower than those currently reached in vivo, may sensitize ACC cells to the cytotoxic effects of doxorubicin and whether this effect is due to a direct action on P-gp. NCI-H295 and SW13 cell lines as well as 4 adrenocortical neoplasia primary cultures were treated with mitotane and doxorubicin, and cell viability was measured by MTT assay. P-gp activity was measured by calcein and P-gp-Glo assays. P-gp expression was evaluated by Western blot. We found that very low mitotane concentrations sensitize ACC cells to the cytotoxic effects of doxorubicin, depending on P-gp expression. In addition, mitotane directly inhibits P-gp detoxifying function, allowing doxorubicin cytotoxic activity. These data provide the basis for the greater efficacy of combination therapy (mitotane plus chemotherapeutic drugs) on ACC patients. Shedding light on mitotane mechanisms of action could result in an improved design of drug therapy for patients with ACC.

Hescot S, Paci A, Seck A, et al.
The lack of antitumor effects of o,p'DDA excludes its role as an active metabolite of mitotane for adrenocortical carcinoma treatment.
Horm Cancer. 2014; 5(5):312-23 [PubMed] Free Access to Full Article Related Publications
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.

Kerkhofs TM, Derijks LJ, Ettaieb H, et al.
Development of a pharmacokinetic model of mitotane: toward personalized dosing in adrenocortical carcinoma.
Ther Drug Monit. 2015; 37(1):58-65 [PubMed] Related Publications
BACKGROUND: Mitotane is the drug of choice in medical treatment of adrenocortical carcinoma. The antineoplastic effect seems to be correlated with a minimum plasma level of 14 mg/L, but plasma concentration build-up is in general slow due to the long elimination half-life. Consequently, the therapeutic effect sets in after weeks or even months. The objective of this study was to develop a pharmacokinetic model that enables clinicians to adjust dosing based on a target drug exposure, which facilitates personalized therapy.
METHODS: Data on dosing and plasma level measurements performed throughout mitotane therapy were retrospectively collected in a population of 29 patients from 2 hospitals. A population pharmacokinetic model was constructed based on data from 20 patients using iterative 2-stage Bayesian fitting (MWPharm). The model was validated in an independent sample of 9 patients.
RESULTS: The concentration-time data were best described by a 3-compartment model. The model estimated mitotane clearance at 0.94 ± 0.37 L/h and a volume of distribution in the steady state at 161 ± 68 L/kg of lean body mass. The mean prediction error was 14% ± 13%.
CONCLUSIONS: A pharmacokinetic model was developed, which characterized mitotane by slow clearance and large volume of distribution. The model seems to be able to predict mitotane levels in individual patients with an error margin of 14%. The model enables one to adapt dosing based on individual plasma level measurements in prospective setting, which improves the accuracy of the prediction. We expect that individualization of mitotane dosing leads to anticipated and more rapid attainment of the therapeutic levels and potentially to improved clinical management of mitotane treatment.

Lerario AM, Worden FP, Ramm CA, et al.
The combination of insulin-like growth factor receptor 1 (IGF1R) antibody cixutumumab and mitotane as a first-line therapy for patients with recurrent/metastatic adrenocortical carcinoma: a multi-institutional NCI-sponsored trial.
Horm Cancer. 2014; 5(4):232-9 [PubMed] Free Access to Full Article Related Publications
Adrenocortical carcinoma (ACC) is an aggressive malignancy, which lacks an effective systemic treatment. Abnormal activation of insulin-like growth factor receptor 1 (IGF1R) has been frequently observed. Preclinical studies demonstrated that pharmacological inhibition of IGF1R signaling in ACC has antiproliferative effects. A previous phase I trial with an IGF1R inhibitor has demonstrated biological activity against ACC. The objective of this study is to assess the efficacy of the combination of the IGF1R inhibitor cixutumumab (IMC-A12) in association with mitotane as a first-line treatment for advanced/metastatic ACC. We conducted a multicenter, randomized double-arm phase II trial in patients with irresectable recurrent/metastatic ACC. The original protocol included two treatment groups: IMC-A12 + mitotane and mitotane as a single agent, after an initial single-arm phase for safety evaluation with IMC-A12 + mitotane. IMC-A12 was dosed at 10 mg/kg intravenously every 2 weeks. The starting dose for mitotane was 2 g daily, subsequently adjusted according to serum levels/symptoms. The primary endpoint was progression-free survival (PFS) according to RECIST (Response Evaluation Criteria in Solid Tumors). This study was terminated before the randomization phase due to slow accrual and limited efficacy. Twenty patients (13 males, 7 females) with a median age of 50.2 years (range 21.9-79.6) were enrolled for the single-arm phase. Therapeutic effects were observed in 8/20 patients, including one partial response and seven stable diseases. The median PFS was 6 weeks (range 2.66-48). Toxic events included two grade 4 (hyperglycemia and hyponatremia) and one grade 5 (multiorgan failure). Although the regimen demonstrated activity in some patients, the relatively low therapeutic efficacy precluded further studies with this combination of drugs.

Terzolo M, Zaggia B, Allasino B, De Francia S
Practical treatment using mitotane for adrenocortical carcinoma.
Curr Opin Endocrinol Diabetes Obes. 2014; 21(3):159-65 [PubMed] Related Publications
PURPOSE OF REVIEW: Description of novel findings about the mechanism of action of mitotane and its activity as an adjunctive postoperative measure, or for treatment of advanced adrenocortical carcinoma.
RECENT FINDINGS: Several in-vitro studies have shown that mitotane suppresses gene transcription of different enzymatic steps of the steroidogenetic pathway. Moreover, mitotane induces CYP3A4 expression, thus accelerating the metabolic clearance of a variety of drugs including steroids. Retrospective studies provided evidence that adjunctive mitotane can prolong recurrence-free survival of treated patients. The concept of a therapeutic window of mitotane plasma concentrations was confirmed also for adjunctive treatment, but the relationship between mitotane concentration and given dose is loose. Genetic variability of the P450-dependent enzymes metabolizing mitotane may explain individual differences.
SUMMARY: Mitotane concentration of 14-20  mg/l should be reached and maintained during treatment also in an adjunctive setting. In advanced adrenocortical carcinoma, a high-dose starting regimen should be employed when mitotane is used as monotherapy. The combination of mitotane with other drugs should consider the possibility of pharmacologic interactions due to mitotane-induced activation of drug metabolism. This concept applies also to steroid replacement in mitotane-treated patients, who need higher doses to adjust for increased steroid metabolism.

Manenschijn L, Quinkler M, van Rossum EF
Hair cortisol measurement in mitotane-treated adrenocortical cancer patients.
Horm Metab Res. 2014; 46(4):299-304 [PubMed] Related Publications
The only approved drug for the treatment of adrenocortical cancer (ACC) is mitotane. Mitotane is adrenolytic and therefore, hydrocortisone replacement therapy is necessary. Since mitotane increases cortisol binding globulin (CBG) and induces CYP3A4 activity, high doses of hydrocortisone are thought to be required. Evaluation of hydrocortisone therapy in mitotane-treated patients has been difficult since there is no good marker to evaluate hydrocortisone therapy. Measurement of cortisol in scalp hair is a novel method that offers the opportunity to measure long-term cortisol levels. Our aim was to evaluate whether hair cortisol measurements could be useful in evaluating recent hydrocortisone treatment in mitotane-treated ACC patients. Hair cortisol levels were measured in 15 mitotane-treated ACC patients on hydrocortisone substitution and 96 healthy individuals. Cortisol levels were measured in 3 cm hair segments, corresponding to a period of 3 months. Hair cortisol levels were higher in ACC patients compared to healthy individuals (p<0.0001). Seven ACC patients (47%) had hair cortisol levels above the reference range. None of the patients had hair cortisol levels below normal. In contrast to hydrocortisone doses (β=0.03, p=0.93), hair cortisol levels were associated with BMI (β=0.53, p=0.042). There was no correlation between hair cortisol levels and hydrocortisone doses (β=0.41, p=0.13). Almost half of the ACC patients had high hair cortisol levels, suggesting long-term over-substitution of hydrocortisone in some of the patients, whereas none of the patients was under-substituted. Hair cortisol measurements might be useful in long-term monitoring hydrocortisone treatment in mitotane-treated ACC patients.

Berruti A, Fassnacht M, Haak H, et al.
Prognostic role of overt hypercortisolism in completely operated patients with adrenocortical cancer.
Eur Urol. 2014; 65(4):832-8 [PubMed] Related Publications
BACKGROUND: Although prognostic parameters are important to guide adjuvant treatment, very few have been identified in patients with completely resected adrenocortical carcinoma (ACC).
OBJECTIVE: To assess the prognostic role of clinical symptoms of hypercortisolism in a large series of patients with completely resected ACC.
DESIGN, SETTING, AND PARTICIPANTS: A total of 524 patients followed at referral centers for ACC in Europe and the United States entered the study. Inclusion criteria were ≥18 yr of age, a histologic diagnosis of ACC, and complete surgery (R0). Exclusion criteria were a history of other malignancies and adjuvant systemic therapies other than mitotane.
INTERVENTION: All ACC patients were completely resected, and adjuvant mitotane therapy was prescribed at the discretion of the investigators.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary end point was overall survival (OS). The secondary end points were recurrence-free survival (RFS) and the efficacy of adjuvant mitotane therapy according to cortisol secretion.
RESULTS AND LIMITATIONS: Overt hypercortisolism was observed in 197 patients (37.6%). Patients with cortisol excess were younger (p=0.002); no difference according to sex and tumor stage was observed. The median follow-up of the series was 50 mo. After adjustment for sex, age, tumor stage, and mitotane treatment, the prognostic significance of cortisol excess was highly significant for both RFS (hazard ratio [HR]: 1.30; 95% confidence interval [CI], 1.04-2.62; p=0.02) and OS (HR: 1.55; 95% CI, 1.15-2.09; p=0.004). Mitotane administration was associated with a reduction of disease progression (adjusted HR: 0.65; 95% CI, 0.49-0.86; p=0.003) that did not differ according to the patient's secretory status. A major limitation is that only symptomatic patients were considered as having hypercortisolism, thus excluding information on the prognostic role of elevated cortisol levels in the absence of a clinical syndrome.
CONCLUSIONS: Clinically relevant hypercortisolism is a new prognostic factor in patients with completely resected ACC. The efficacy of adjuvant mitotane does not seem to be influenced by overt hypercortisolism.

Kerkhofs TM, Baudin E, Terzolo M, et al.
Comparison of two mitotane starting dose regimens in patients with advanced adrenocortical carcinoma.
J Clin Endocrinol Metab. 2013; 98(12):4759-67 [PubMed] Related Publications
CONTEXT: Mitotane is the only approved drug for treatment of adrenocortical carcinoma. Its pharmacokinetic properties are not fully elucidated and different dosing regimens have never been compared head to head.
OBJECTIVE: The objective of the study was to investigate the relationship between mitotane dose and plasma concentration comparing two dosing regimens.
DESIGN/SETTING: This was a prospective, open-label, multicenter trial of a predefined duration of 12 weeks.
PATIENTS/INTERVENTIONS: Forty mitotane-naïve patients with metastatic adrenocortical carcinoma were assigned to a predefined low- or high-dose regimen by the local investigator. Thirty-two patients could be evaluated in detail.
MAIN OUTCOME MEASURE: The difference in median mitotane plasma levels between both treatment groups was measured.
RESULTS: Despite a difference in mean cumulative dose (440 ± 142 g vs 272 ± 121 g), median maximum plasma levels were not significantly different between the two groups [high dose 14.3 mg/L (range 6.3-29.7, n = 20) vs 11.3 mg/L (range 5.5-20.0, n = 12), P = .235]. Ten of 20 patients on the high-dose regimen reached plasma concentrations of 14 mg/L or greater after 46 days (range 18-81 d) compared with 4 of 12 patients on the low-dose regimen after 55 days (range 46-74 d, P = .286). All patients who reached 14 mg/L at 12 weeks displayed a level of 4.1 mg/L or greater on day 33 (100% sensitivity). There were no significant differences in frequency and severity of adverse events. Among patients not receiving concomitant chemotherapy mitotane exposure was higher in the high-dose group: 1013 ± 494 mg/L · d vs 555 ± 168 mg/L · d (P = .080).
CONCLUSIONS: The high-dose starting regimen resulted in neither significantly different mitotane levels nor a different rate of adverse events, but concomitant chemotherapy influenced these results. Thus, for mitotane monotherapy the high-dose approach is favorable, whereas for combination therapy a lower dose seems reasonable.

Germano A, Rapa I, Volante M, et al.
Cytotoxic activity of gemcitabine, alone or in combination with mitotane, in adrenocortical carcinoma cell lines.
Mol Cell Endocrinol. 2014; 382(1):1-7 [PubMed] Related Publications
We aimed at investigating in vitro the cytotoxic activity (determined using WST-1, apoptosis and cell cycle assays) of gemcitabine, alone or in combination with mitotane, in mitotane-sensitive H295R and mitotane-insensitive SW-13 cells. Results of these experiments were compared with drug-induced modulation of RRM1 gene, the specific target of gemcitabine. In H295R cells, mitotane and gemcitabine combinations showed antagonistic effects and interfered with the gemcitabine-mediated inhibition of the S phase of the cell cycle. By contrast, in SW-13 cells, except when mitotane was sequentially administered prior to gemcitabine, the combination of the two drugs was synergistic. Such opposite effects were associated with opposite expression profiles of the target gene, with significant up-modulation in H295R but not in SW-13 under gemcitabine and mitotane combination treatment.

Doghman M, Lalli E
Lack of long-lasting effects of mitotane adjuvant therapy in a mouse xenograft model of adrenocortical carcinoma.
Mol Cell Endocrinol. 2013; 381(1-2):66-9 [PubMed] Related Publications
Mitotane is a widely used drug in the therapy of adrenocortical carcinoma (ACC). It is important to set up preclinical protocols to study the possible synergistic effects of its association with new drugs for ACC therapy. We assessed the efficacy of different routes of administration of mitotane (i.p. and oral) in inhibiting growth of H295R ACC cell xenografts in an adjuvant setting. Both formulations of mitotane could inhibit H295R xenografts growth only at short times after carcinoma cells inoculation, even though plasma mitotane levels approached or fell within the therapeutic range in humans. Our results show that mitotane adjuvant therapy is inadequate to antagonize long-term growth of H295R cancer cells xenografts and that care should then be taken in the design of preclinical protocols to evaluate the performance of new drugs in association with mitotane.

Gentilin E, Tagliati F, Terzolo M, et al.
Mitotane reduces human and mouse ACTH-secreting pituitary cell viability and function.
J Endocrinol. 2013; 218(3):275-85 [PubMed] Related Publications
Medical therapy for Cushing's disease (CD) is currently based on agents mainly targeting adrenocortical function. Lately, pituitary-directed drugs have been developed, with limited efficacy. Mitotane, a potent adrenolytic drug, has been recently investigated for the treatment of CD, but the direct pituitary effects have not been clarified so far. The aim of our study was to investigate whether mitotane may affect corticotroph function and cell survival in the mouse pituitary cell line AtT20/D16v-F2 and in the primary cultures of human ACTH-secreting pituitary adenomas, as an in vitro model of pituitary corticotrophs. We found that in the AtT20/D16v-F2 cell line and in primary cultures, mitotane reduces cell viability by inducing caspase-mediated apoptosis and reduces ACTH secretion. In the AtT20/D16v-F2 cell line, mitotane reduces Pomc expression and blocks the stimulatory effects of corticotropin-releasing hormone on cell viability, ACTH secretion, and Pomc expression. These effects were apparent at mitotane doses greater than those usually necessary for reducing cortisol secretion in Cushing's syndrome, but still in the therapeutic window for adrenocortical carcinoma treatment. In conclusion, our results demonstrate that mitotane affects cell viability and function of human and mouse ACTH-secreting pituitary adenoma cells. These data indicate that mitotane could have direct pituitary effects on corticotroph cells.

Poli G, Guasti D, Rapizzi E, et al.
Morphofunctional effects of mitotane on mitochondria in human adrenocortical cancer cells.
Endocr Relat Cancer. 2013; 20(4):537-50 [PubMed] Related Publications
At present, mitotane (MTT) represents the first-line pharmacological approach for the treatment of advanced adrenocortical carcinoma (ACC). Despite clear evidence that the drug can reduce the clinical signs of steroid excess in secreting ACC, the mechanism mediating the possible toxic effect of MTT on tumor cells still remains obscure. This study investigated the intracellular events underlying the toxic effect of MTT by studying qualitative and quantitative alterations in mitochondrial morphology and functions in human adrenocortical cancer cell lines, H295R and SW13. Increasing concentrations of MTT resulted in rapid intracellular accumulation and conversion of the drug. Cytostatic and cytotoxic effects were evident at doses corresponding to the therapeutic window (30-50 μM) through an apoptotic mechanism involving caspase 3/7. Electron microscopic analysis of cell mitochondria displayed MTT-induced dose- and time-dependent alterations in the morphology of the organelle. These alterations were characterized by a marked swelling and a decrease in the number of respiratory cristae, accompanied by a significant depolarization of the mitochondrial membrane potential, finally leading to the disruption of the organelle. A drastic reduction of oxygen consumption was observed due to mitochondrial membrane damage, which was accompanied by a decrease in the levels of VDAC1 integral membrane channel. These findings contribute to better understand the intracellular mechanism of action of MTT in ACC cells, showing that its cytotoxic effect seems to be mainly mediated by an apoptotic process activated by the disruption of mitochondria.

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