High-dose mitotane strategy in adrenocortical carcinoma: prospective analysis of plasma mitotane measurement during the first 3 months of follow-up

Adverse Events of Adjuvant Mitotane Treatment for Adrenocortical Carcinoma

BACKGROUND

Mitotane is the cornerstone of adjuvant adrenocortical cancer (ACC) treatment. However, its use is burdened with frequent adverse events.

METHODS

A retrospective analysis of adverse events was performed in 26 ACC patients adjuvantly treated with mitotane.

RESULTS

Mitotane toxicity was present in all patients (100%). Two (7.7%) patients developed 1-3 adverse events, 15 (57.7%) experienced 4-6 adverse events and 9 (34.6%) patients had more than 6 adverse events. Two (7.7%) patients discontinued mitotane due to adverse events.

CONCLUSION

Careful monitoring and timely management are essential for ensuring mitotane treatment adherence and maximizing its benefits.

A Review on Mitotane: A Target Therapy in Adrenocortical Carcinoma

Adrenocortical carcinomas (ACCs) are rare and aggressive malignancies of adrenal cortex, associated with largely unknown mechanisms of biological development and poor prognosis. Currently, mitotane is the sole approved drug for treating advanced adrenocortical carcinomas (ACCs) and is being utilized more frequently as postoperative adjuvant therapy. Although it is understood that mitotane targets the adrenal cortex and disrupts steroid production, its precise mechanism of action requires further exploration. Additionally, mitotane affects cytochrome P450 enzymes, causes the depolarization of mitochondrial membranes, and leads to an accumulation of free cholesterol, ultimately resulting in cell death. Many patients treated with mitotane develop disease progression over time, underlying the need to understand the mechanisms of primary and acquired resistance. In this manuscript, we provide an overview on the intracellular mechanisms of action of mitotane, exploring data regarding predictive factors of response and evidence associated with the development of primary and acquired resistance mechanisms. In this discussion, mitotane is considered a real target therapy.

Development and validation of a liquid chromatography coupled to a diode array detector (LC-DAD) method for measuring mitotane (DDD) in plasma samples

INTRODUCTION

Mitotane (o,p'-DDD) is the drug of choice for Adrenocortical Carcinomas (ACC) and its measurement in plasma is essential to control drug administration.

OBJECTIVE

To develop and validate a simple, reliable and straightforward method for mitotane determination in plasma samples.

METHOD

Drug-free plasma samples were collected in potassium-ethylenediamine tetraacetate (K-EDTA) tubes and spiked with 1.0, 2.5, 10.0, 25.0 and 50.0 µg/mL of mitotane (DDD). The p,p'-DDD was used as an Internal Standard (IS) and was added at 25.0 µg/mL concentration to all samples, standards and controls. Samples were submitted to protein precipitation with acetonitrile and then centrifuged. 50 uL of the supernatant was injected into an HPLC system coupled to a Diode Array Detector (DAD). DDD and IS were detected at 230 nm in a 12 min isocratic mode with a solvent mixture of 60 % acetonitrile and 40 % formic acid in water with 0.1 % pump mixed, at 0.6 mL/min flow rate, in a reversed-phase (C18) chromatographic column kept at 28°C. The sensitivity, selectivity, precision, presence of carry-over, recovery and matrix-effect, linearity, and method accuracy were evaluated.

RESULTS

The present study's method resulted in a symmetrical peak shape and good baseline resolution for DDD (mitotane) and 4,4'-DDD (internal standard) with retention times of 6.0 min, 6.4 mim, respectively, with resolutions higher than 1.0. Endogenous plasma compounds did not interfere with the evaluated peaks when blank plasma and spiked plasma with standards were compared. Linearity was assessed over the range of 1.00-50.00 µg/mL for mitotane (R2 > 0.9987 and a 97.80 %‒105.50 % of extraction efficiency). Analytical sensitivity was 0.98 µg/mL. Functional sensitivity (LOQ) was 1.00 µg/L, intra-assay and inter-assay coefficient of variations were less than 9.98 %, and carry-over was not observed for this method. Recovery ranged from 98.00 % to 117.00 %, linearity ranged from 95.00 % to 119.00 %, and high accuracy of 89.40 % to 105.90 % with no matrix effects or interference was observed for mitotane measurements. Patients' sample results were compared with previous measurements by the GC-MS method with a high correlation (r = 0.88 and bias = -10.20 %).

CONCLUSION

DDD determination in plasma samples by the developed and validated method is simple, robust, efficient, and sensitive for therapeutic drug monitoring and dose management to achieve a therapeutic index of mitotane in patients with adrenocortical cancer.

Effects of o,p'-DDE, a Mitotane Metabolite, in an Adrenocortical Carcinoma Cell Line

In South Brazil, the incidence of pediatric adrenocortical carcinoma (ACC) is higher than in other regions and countries worldwide. The ACC treatment includes therapy with mitotane, the only adrenolytic drug approved by the FDA. The mitotane metabolism occurs via two main reactions: the β-hydroxylation, which yields the final product o,p'-DDA, and the α-hydroxylation, which will give the final product o,p'-DDE. It is speculated that o,p'-DDE may be an active metabolite since it has a cytotoxic effect on adrenocortical carcinoma cells (H295R). No further studies have been conducted to confirm this hypothesis; however, it was found that mitotane and its metabolites are present at significantly different concentrations in the plasma of the patients. Our study aimed to assess the in vitro effects of o,p'-DDE and o,p'-DDD in cell death pathways, oxidative parameters, and interaction with adrenal CYP's involved in the steroidogenic process in the H295R cell line. It was found that o,p'-DDE had a different effect than the o,p'-DDD on apoptosis, inhibiting this cell death pathway, but it promotes cell necrosis at higher concentrations. In contrast to o,p'-DDD, the o,p'-DDE did not have effects on the different oxidative parameters evaluated, but exhibited stimulatory interactions with steroidogenic CYP's, at intermediate concentrations. Therefore, we demonstrated important cell effects of o,p'-DDE; its plasma levels during mitotane therapy should be monitored as an important therapeutic parameter.

Sex-Based Evaluation of Lipid Profile in Postoperative Adjuvant Mitotane Treatment for Adrenocortical Carcinoma

Background: A wide interindividual variability in mitotane concentrations and treatment-related dyslipidemia have been reported. Here, we aimed to underline the sex-related differences in the lipid profile in patients that underwent radical surgery of adrenocortical carcinoma during treatment with adjuvant mitotane. Methods: A chromatographic method was used to quantify the drug in plasma collected from adult patients with complete tumor resection, also considering active metabolite o,p’-DDE. Results: We observed different lipid profiles between males and females and between pre- and post-menopausal women. Considering the mitotane-related effects on lipid levels, we observed that higher drug concentrations were correlated with higher HDL in all the considered groups (p < 0.001), with total cholesterol both in males (p = 0.005) and females (p = 0.036), with triglycerides in postmenopausal females (p = 0.002) and with LDL in male patients (p < 0.001). Increases in o,p’-DDE were positively correlated with HDL levels in all the groups (p < 0.001) and negatively with LDL in all the groups (males p = 0.008, pre- and post-menopausal females p < 0.001), with total cholesterol in pre- (p = 0.016) and post-menopausal women (p = 0.01) and with triglycerides in premenopausal females (p = 0.005). Conclusions: This is the first study designed to evaluate sex differences in lipoprotein and lipid levels during mitotane adjuvant treatment; the results suggest that a gender and personalized approach could be useful to prevent and manage alterations in the lipid profile.

Lived experience of people with adrenocortical carcinoma and associated adrenal insufficiency

Introduction

Adrenocortical carcinoma (ACC) is a rare cancer with an annual incidence of 0.7–2 cases per million population and 5‐year survival of 31.2%. Adrenal insufficiency (AI) is a common and life shortening complication of ACC, and little is understood about how it impacts on patients' experience.

Objective

To understand patients' lived experience of the condition, its treatment, care process, impact of AI on ACC wellbeing, self‐care needs and support.

Methods

Systematic review of MEDLINE, EMBASES, CINAHL, PsycINFO and Open Grey for studies published until February 2021. All research designs were included. The findings underwent a thematic analysis and narrative synthesis. Studies quality was assessed using mixed method assessment tools.

Results

A total of 2837 citations were identified; 15 titles with cohort, cross‐sectional, case series and case report study designs met the inclusion criteria involving 479 participants with adrenal insufficiency secondary to adrenocortical carcinoma (AI/ACC). Quantitative research identified impacts of disease and treatment on survivorship, the burden of living with AI/ACC, toxicity of therapies, supporting self‐care and AI management. These impact factors included adjuvant therapies involved and their toxicities, caregivers/family supports, healthcare and structure support in place, specialist skill and knowledge provided by healthcare professional on ACC management. No qualitative patient experiences evidence was identified.

Conclusion

ACC appears to have high impact on patients' wellbeing including the challenges with self‐care and managing AI. Evidence is needed to understand patient experience from a qualitative perspective.

Mitotane treatment in adrenocortical carcinoma: mechanisms of action and predictive markers of response to therapy

Adrenocortical carcinoma (ACC) is a rare malignancy with a high risk of recurrence even in cases with complete surgical tumor resection. Mitotane represents the cornerstone of the adjuvant therapy as well as the first line of medical treatment in advanced cases. However, evidence on mitotane efficacy is mostly based on retrospective studies and the use of mitotane continues to represent a clinical challenge. Mitotane causes selective damage to adrenocortical cells, causing an increase of cell apoptosis through a disruption of mitochondria and the induction of the endoplasmic reticulum stress. Different clinical and molecular markers predicting response to mitotane have been proposed with uncertain results. Attainment of mitotane plasma levels within the target range of 14 to 20 mg/L represent the strongest predictor of mitotane effectiveness both in adjuvant and advanced tumor setting. The occurrence of late recurrence after primary ACC diagnosis and changes in metabolic activity on FDG-PET are only weakly associated with mitotane response. Among the proposed molecular markers associated with mitotane efficacy, the investigation of the CYP2W1*6 and CYP2B6*6 single nucleotide polymorphisms appears to be currently the most promising predictive molecular markers of mitotane therapy. However, none of the evaluated markers has been validated for clinical use. In the era of precision medicine, a better insight into mitotane molecular mechanisms as well as the potential use in the daily clinical practice of clinical parameters and molecular markers predicting the individual response to mitotane are urgently needed.

Metabolic and Endocrine Toxicities of Mitotane: A Systematic Review

Simple Summary

This is, to our knowledge, the first systematic review conducted on the endocrine effects of mitotane, which aims to collect all available evidence in the literature and provide complete and useful information regarding the management of the endocrine and metabolic side effects of mitotane in clinical practice.

Abstract

Despite the pivotal role of mitotane in adrenocortical carcinoma (ACC) management, data on the endocrine toxicities of this treatment are lacking. The aim of this systematic review is to collect the available evidence on the side effects of mitotane on the endocrine and metabolic systems in both children and adults affected by adrenal carcinoma. Sixteen articles on 493 patients were included. Among the adrenal insufficiency, which is an expected side effect of mitotane, 24.5% of patients increased glucocorticoid replacement therapy. Mineralocorticoid insufficiency usually occurred late in treatment in 36.8% of patients. Thyroid dysfunction is characterized by a decrease in FT4, which occurs within 3–6 months of treatment in 45.4% of patients, while TSH seems to not be a reliable marker. Dyslipidemia is characterized by an increase in both LDL-c and HDL-c (54.2%). Few studies have found evidence of hypertriglyceridemia. In males, gynecomastia and hypogonadism can occur after 3–6 months of treatment (38.4% and 35.6%, respectively), while in pre-menopausal women, mitotane can cause ovarian cysts and, less frequently, menstrual disorders. Most of these side effects appear to be reversible after mitotane discontinuation. We finally suggest an algorithm that could guide metabolic and endocrine safety assessments in patients treated with mitotane for ACC.

How close are we to personalized mitotane dosing in the treatment of adrenocortical carcinoma? State of the art and future perspectives

INTRODUCTION

Mitotane is the only drug registered specifically for adrenocortical carcinoma. Finding the optimal dose for a patient is difficult due to large differences in bioavailability, toxicity and effect. We therefore look to improve personalized dosing of mitotane.

AREAS COVERED

We searched PubMed for studies related to mitotane dosing, pharmacokinetics, pharmacogenetics and combination therapy. Comparison of different dosing strategies have not resulted in an optimal advice. Several computerized pharmacokinetic models have been proposed to predict plasma levels. The current pharmacokinetic models do not explain the full variance in plasma levels. Pharmacogenetics have been proposed to find the unexplained variance. Studies on combination therapy have not yet led to a potential dose adjustment for mitotane.

EXPERT OPINION

Computerized pharmacokinetics models are promising tools to predict plasma levels, further validation is needed. Pharmacogenetics are introduced in these models, but more research is required before clinical application. We believe that in the near future, personalized mitotane dosage will be aided by a validated web-based pharmacokinetic model with good predictive ability based primarily on clinical characteristics, adjustable for actual plasma levels and dosage.

Pharmacological profile and effects of mitotane in adrenocortical carcinoma

Mitotane is the only adrenolytic drug approved by the Food and Drug Administration for treating adrenocortical carcinoma (ACC). This drug has cytotoxic effects on tumour tissues; it induces cell death and antisecretory effects on adrenal cells by inhibiting the synthesis of adrenocortical steroids, which are involved in the pathogenesis of ACC. However, high doses of mitotane are usually necessary to reach the therapeutic plasma concentration, which may result in several adverse effects. This suggests that important pharmacological processes, such as first pass metabolism, tissue accumulation and extensive time for drug elimination, are associated with mitotane administration. Few studies have reported the pharmacological aspects and therapeutic effects of mitotane. Therefore, the aim of this review was to summarize the chemistry, pharmacokinetics and pharmacodynamics, and therapeutic and toxic effects of mitotane. This review also discusses new perspectives of mitotane formulation that are currently under investigation. Understanding the pharmacological profile of mitotane can improve the monitoring and efficacy of this drug in ACC treatment and can provide useful information for the development of new drugs with specific action against ACC with fewer adverse effects.

Adrenally Directed Medical Therapies for Cushing Syndrome

CONTEXT

Endogenous Cushing syndrome (CS) is characterized by excess cortisol secretion, which is driven by tumorous secretion of corticotropin in the majority of patients. Untreated, CS results in substantial morbidity and mortality. Tumor-directed surgery is generally the first-line therapy for CS. However, hypercortisolism may persist or recur postoperatively; in other cases, the underlying tumor may not be resectable or its location may not be known. Yet other patients may be acutely ill and require stabilization before definitive surgery. In all these cases, additional interventions are needed, including adrenally directed medical therapies.

EVIDENCE ACQUISITION

Electronic literature searches were performed to identify studies pertaining to adrenally acting agents used for CS. Data were abstracted and used to compile this review article.

EVIDENCE SYNTHESIS

Adrenally directed medical therapies inhibit one or several enzymes involved in adrenal steroidogenesis. Several adrenally acting medical therapies for CS are currently available, including ketoconazole, metyrapone, osilodrostat, mitotane, and etomidate. Additional agents are under investigation. Drugs differ with regards to details of their mechanism of action, time course of pharmacologic effect, safety and tolerability, potential for drug-drug interactions, and route of administration. All agents require careful dose titration and patient monitoring to ensure safety and effectiveness, while avoiding hypoadrenalism.

CONCLUSIONS

These medications have an important role in the management of CS, particularly among patients with persistent or recurrent hypercortisolism postoperatively or those who cannot undergo tumor-directed surgery. Use of these drugs mandates adequate patient instruction and close monitoring to ensure treatment goals are being met while untoward adverse effects are minimized.

A case report of neurological adverse events caused by short-term and low-dose treatment of mitotane: The role of therapeutic drug monitoring

RATIONALE

Low-dose mitotane has been widely used for many decades in patients with advanced adrenocortical carcinoma (ACC), which exhibited good safety profiles compared with the high-dose regimen. The clinical efficacy and toxicity of mitotane are closely related to its plasma concentration, and therapeutic drug monitoring (TDM) is recommended. Until now, no severe adverse drug reaction (ADR) related to the toxic plasma level after a short-term treatment of low-dose mitotane has been published.

PATIENT CONCERNS

A 50-year-old Chinese female presented with severe neurological adverse events related to a toxic plasma levels of 42.8 mg/L after 4 months treatment of low-dose mitotane.

DIAGNOSES

During the course of therapy, no other medication could cause neurological adverse events. Therefore, we suspected a high sensitivity to the side effect of mitotane related to a toxic plasma level.

INTERVENTIONS

Treatment of mitotane was stopped.

OUTCOMES

The trough plasma concentration of mitotane decreased to 18.7 mg/mL after one and a half months, and the neurological symptoms gradually improved after drug discontinuance.

LESSONS

The present case provides the first report of severe neurological adverse events induced by the short-term use of low-dose mitotane for adjuvant treatment in a patient with ACC, indicating that potentially severe ADR can also occur when using low-dose regimen in the early stage of treatment. TDM and early recognition could result in a favorable outcome.

Advances in the Medical Treatment of Cushing Disease

Medical therapy has an adjunctive role in management of Cushing disease. Medical therapy is recommended for patients who received pituitary radiotherapy and are awaiting its salutary effects. Medications are used preoperatively to stabilize the condition of seriously ill patients before surgery. Medical therapy is used to control hypercortisolism in patients with uncertain tumor location. Medical therapies available for management of patients with Cushing disease include steroidogenesis inhibitors, centrally acting agents, and glucocorticoid receptor antagonists. All agents require careful monitoring to optimize clinical effectiveness and manage adverse effects. Novel agents in development may expand the armamentarium for management of this condition.

Expression of SOAT1 in Adrenocortical Carcinoma and Response to Mitotane Monotherapy: An ENSAT Multicenter Study

CONTEXT

Objective response rate to mitotane in advanced adrenocortical carcinoma (ACC) is approximately 20%, and adverse drug effects are frequent. To date, there is no marker established that predicts treatment response. Mitotane has been shown to inhibit sterol-O-acyl transferase 1 (SOAT1), which leads to endoplasmic reticulum stress and cell death in ACC cells.

OBJECTIVE

To investigate SOAT1 protein expression as a marker of treatment response to mitotane.

PATIENTS

A total of 231 ACC patients treated with single-agent mitotane as adjuvant (n = 158) or advanced disease therapy (n = 73) from 12 ENSAT centers were included. SOAT1 protein expression was determined by immunohistochemistry on formalin-fixed paraffin-embedded specimens.

SETTING

Retrospective study at 12 ACC referral centers.

MAIN OUTCOME MEASURE

Recurrence-free survival (RFS), progression-free survival (PFS), and disease-specific survival (DSS).

RESULTS

Sixty-one of 135 patients (45%) with adjuvant mitotane treatment had recurrences and 45/68 patients (66%) with mitotane treatment for advanced disease had progressive disease. After multivariate adjustment for sex, age, hormone secretion, tumor stage, and Ki67 index, RFS (hazard ratio [HR] = 1.07; 95% confidence interval [CI], 0.61-1.85; P = 0.82), and DSS (HR = 1.30; 95% CI, 0.58-2.93; P = 0.53) in adjuvantly treated ACC patients did not differ significantly between tumors with high and low SOAT1 expression. Similarly, in the advanced stage setting, PFS (HR = 1.34; 95% CI, 0.63-2.84; P = 0.45) and DSS (HR = 0.72; 95% CI, 0.31-1.70; P = 0.45) were comparable and response rates not significantly different.

CONCLUSIONS

SOAT1 expression was not correlated with clinical endpoints RFS, PFS, and DSS in ACC patients with mitotane monotherapy. Other factors appear to be relevant for mitotane treatment response and ACC patient survival.

Current management of Cushing's disease

Cushing's disease (CD) is caused by a pituitary tumour that secretes adrenocorticotropin (ACTH) autonomously, leading to excess cortisol secretion from the adrenal glands. The condition is associated with increased morbidity and mortality that can be mitigated by treatments that result in sustained endocrine remission. Transsphenoidal pituitary surgery (TSS) remains the mainstay of treatment for CD but requires considerable neurosurgical expertise and experience in order to optimize patient outcomes. Up to 90% of patients with microadenomas (tumour below 1 cm in largest diameter) and 65% of patients with macroadenomas (tumour at or above 1 cm in greatest diameter) achieve endocrine remission after TSS by an experienced surgeon. Patients who are not in remission postoperatively or those who relapse may benefit from undergoing a second pituitary operation. Alternatively, radiation therapy to the sella with interim medical therapy, or bilateral adrenalectomy, can be effective as definitive treatments of CD. Medical therapy is currently adjunctive in most patients with CD and is generally prescribed to patients who are about to receive radiation therapy and will be awaiting its salutary effects to occur. Available treatment options include steroidogenesis inhibitors, centrally acting agents and glucocorticoid receptor antagonists. Several novel agents are in clinical trials and may eventually constitute additional treatment options for this serious condition.

Population Pharmacokinetics Modelling and Simulation of Mitotane in Patients with Adrenocortical Carcinoma: An Individualized Dose Regimen to Target All Patients at Three Months?

Mitotane is the most effective agent in post-operative treatment of adrenocortical carcinoma. In adults, the starting dose is 2–3 g/day and should be slightly increased to reach the therapeutic index of 14–20 mg/L. This study developed a population PK model for mitotane and to simulate recommended/high dosing regimens. We retrospectively analyzed the data files of 38 patients with 503 plasma concentrations for the pharmacokinetic analysis. Monolix version 2019R1 was used for non-linear mixed-effects modelling. Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA ≥ 14 mg/L) at one month and at three months. Mitotane concentration data were best described by a linear one-compartment model. The estimated PK parameters (between-subject variability) were: 8900 L (90.4%) for central volume of distribution (V) and 70 L·h⁻¹ (29.3%) for clearance (Cl). HDL, Triglyceride (Tg) and a latent covariate were found to influence Cl. The PTA at three months for 3, 6, 9, and 12 g per day was 10%, 55%, 76%, and 85%, respectively. For a loading dose of 15 g/day for one month then 5 g/day, the PTA in the first and third months was 57 and 69%, respectively. This is the first PKpop model of mitotane highlighting the effect of HDL and Tg covariates on the clearance as well as a subpopulation of ultrafast metabolizer. The simulations suggest that recommended dose regimens are not enough to target the therapeutic threshold in the third month.

A method for the minimally invasive drug monitoring of mitotane by means of volumetric absorptive microsampling for a home-based therapeutic drug monitoring

Mitotane is the only currently approved treatment for adrenocortical carcinoma (ACC), a rare endocrine malignancy. Plasma levels within the range of 14 to 20 mg L^-1 are correlated with higher clinical efficacy and manageable toxicity. Because of this narrow therapeutic index and slow pharmacokinetics, therapeutic drug monitoring is an essential element of mitotane therapy. A small step towards the therapeutic drug monitoring (TDM) by volumetric absorptive microsampling (VAMS) was made with this work. A simple method enabling the patient to collect capillary blood at home for the control of mitotane blood concentration was developed and characterized using MITRA™ VAMS 20 μL microsampler. Dried blood samples were extracted prior to HPLC-UV analysis. Mitotane and the internal standard dicofol (DIC) were detected at 230 nm by ultra-violet detection after separation on a C8 reversed phase column. The assay was validated in the range of 1 to 50 mg L^-1. Dried samples were stable at room temperature and at 2-8 °C for 1 week. At 37 °C, a substantial amount of the analyte was lost probably due to evaporation. Hematocrit bias, a common problem of conventional dried blood techniques, was acceptable in the tested range. However, a significant difference in recovery from spiked and authentic patient blood was detected. Comparison of mitotane concentration in dried blood samples (C_DBS) by VAMS with venous plasma in patients on mitotane therapy demonstrated poor correlation of C_DBS with the concentration in plasma (C_P)_. In conclusion, application of VAMS in clinical routine for mitotane TDM appears to be of limited value in the absence of a method-specific target range.

Enzyme autoinduction by mitotane supported by population pharmacokinetic modelling in a large cohort of adrenocortical carcinoma patients

OBJECTIVE

Mitotane is used for the treatment of adrenocortical carcinoma. High oral daily doses of typically 1- 6 g are required to attain therapeutic concentrations. The drug has a narrow therapeutic index and patient management is difficult because of a high volume of distribution, very long elimination half-life, and drug interaction through induction of metabolizing enzymes. The present evaluation aimed at the development of a population pharmacokinetic model of mitotane to facilitate therapeutic drug monitoring.

METHODS

Appropriate dosing information, plasma concentrations (1137 data points) and covariates were available from therapeutic drug monitoring (TDM) of 76 adrenocortical carcinoma patients treated with mitotane. Using nonlinear mixed effects modeling, a simple structural model was first developed, with subsequent introduction of metabolic autoinduction. Covariate data were analyzed to improve overall model predictability. Simulations were performed to assess the attainment of therapeutic concentrations with clinical dosing schedules.

RESULTS

A one-compartment pharmacokinetic model with first order absorption was found suitable to describe the data, with an estimated central volume of distribution of 6086 L related to a high interindividual variability of 81.5%. Increase in clearance of mitotane during treatment could be modeled by a linear enzyme autoinduction process. Body mass index was found to have an influence upon disposition kinetics of mitotane. Model simulations favor a high dose regimen to rapidly attain therapeutic concentrations, with the first TDM suggested on day 16 of treatment to avoid systemic toxicity.

CONCLUSION

The proposed model describes mitotane pharmacokinetics and can be used to facilitate therapy by predicting plasma concentrations.

Medical Therapy for Cushing's Syndrome in the Twenty-first Century

Medical therapy has a useful adjunctive role in many patients with Cushing's syndrome. Patients with pituitary corticotroph adenomas who have received radiation therapy to the sella require medical therapy until the effects of radiation therapy occur. In addition, patients with Cushing's syndrome who cannot undergo surgery promptly, including those who are acutely ill and cannot safely undergo tumor resection, may benefit from medical therapy as a bridge to surgery. Other possible candidates for medical therapy are those with unresectable tumors or those whose tumor location remains unknown despite adequate diagnostic evaluation.

Therapeutic drug monitoring of mitotane: Analytical assay and patient follow-up

Adrenocortical carcinoma (ACC) is an aggressive malignancy of the adrenal gland. Mitotane (o,p'-DDD) is the most effective chemotherapy for ACC. According to the literature, mitotane plasma trough concentrations within 14-20 mg L^-1 are correlated with a higher response rate with acceptable toxicity. Therapeutic drug monitoring (TDM) of mitotane is therefore recommended. The aim of this study was to propose a robust and simple method for mitotane quantification in plasma. The validation procedures were based on international guidelines. Sample preparation consisted of a single protein precipitation with methanol using 100 μL of plasma. The supernatant was submitted to liquid chromatography coupled with ultra-violet detection at 230 nm. Mitotane retention time was 7.1 min. The limit of detection was 0.1 mg L^-1 and the limit of quantification was 0.78 mg L^-1 . The assay demonstrated a linear range of 0.78-25 mg L^-1 with correlation coefficients (r² ) at 0.999. Inter- and intra-assay precision was <4.85%. Evaluation of accuracy showed a deviation <13.69% from target concentration at each quality control level. This method proved easy and rapid to perform mitotane TDM and required a small volume of sample. It was successfully applied to routine TDM in our laboratory.

New insights and future perspectives in the therapeutic strategy of adrenocortical carcinoma (Review)

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with an incidence ranging from 0.7 to 2.0 cases/million people per year. Hypercortisolism represents the most common clinical presentation in many patients although, less frequently, some ACC secreting androgens and estrogens are even more pathognomonic compared to cortisol secretion. Currently, radical surgery, when feasible, is still the only curative therapy. Mitotane, an adrenolytic drug, is used in the adjuvant setting and in combination with chemotherapy drugs in metastatic disease. The use of radiotherapy remains controversial, being indicated only in selected cases. New targeted therapies, such as insulin growth factor-1 (IGF-1), mammalian-target of rapamycin (m-TOR), vascular endothelial growth factor (VEGF) inhibitors and others, have recently been investigated with disappointing clinical results. The partial effectiveness of current treatments mandates the need for new therapeutic strategies against this tumor.

Dyslipidemia causes overestimation of plasma mitotane measurements

Mitotane (o,p′-DDD) is the standard treatment for advanced adrenocortical carcinoma (ACC). Monitoring of plasma mitotane levels is recommended to look for a therapeutic window between 14 and 20mg/L, but its positive predictive value requires optimization. We report the case of an ACC patient with a history of dyslipidemia treated with mitotane in whom several plasma mitotane levels >30mg/L were found together with an excellent neurological tolerance. This observation led us to compare theoretical or measured o,p′-DDD and o,p′-DDE levels in a series of normolipidemic and dyslipidemic plasma samples to explore potential analytical issues responsible for an overestimation of plasma mitotane levels. We demonstrate an overestimation of mitotane measurements in dyslipidemic patients. Mitotane and o,p′-DDE measurements showed a mean 20% overestimation in hypercholesterolemic and hypertriglyceridemic plasma, compared with normolipidemic plasma. The internal standard p,p′-DDE measurements showed a parallel decrease in hypercholesterolemic and hypertriglyceridemic plasma, suggesting a matrix effect. Finally, diluting plasma samples and/or using phospholipid removal cartridges allowed correcting such interference.

Learning points

Adrenocortical carcinoma: Retrospective analysis of the last 22 years

BACKGROUND

Adrenocortical carcinoma (ACC) is a rare disease with a poor prognosis. The clinical experience acquired, even from a small number of cases, has improved understanding of this condition. The purpose of this study is to characterize patients with ACC followed up at a Portuguese reference center over the past 22 years.

METHODS

Retrospective analysis of clinical records of patients with histopathological diagnosis of ACC followed up from 1992 to 2014.

RESULTS

The study sample consisted of 22 patients, 20 of them female. Eleven patients were in stage II, four in stage III, and five in stage IV; 13 patients had functioning lesions. Adrenalectomy was performed in 20 patients, with complete tumor resection in 90% of the cases. During follow-up, eight patients experienced recurrence of local disease, and 12 distant metastases. Fourteen patients received mitotane, 35.7% (n=5) as adjuvant therapy and 64.3% (n=9) after recurrence; therapeutic plasma mitotane levels were achieved in 70% of patients. Stage III patients who received adjuvant therapy had longer survival time (13.5 vs. 2.5 months). Two patients were given chemotherapy associated to mitotane. Median survival was 11 months (0-257 months); it was slightly longer in younger patients or patients with non-functioning tumors. Six patients are still alive, four of them with no evidence of disease.

CONCLUSION

Despite the overall poor prognosis, some patients with ACC may have a long survival time. Although complete tumor removal remains the only potentially curative treatment, diagnosis at a younger age, presence of non-functioning tumors, and mitotane treatment also seemed to be associated to longer survival in our patients.

Rapid and Complete Remission of Metastatic Adrenocortical Carcinoma Persisting 10 Years After Treatment With Mitotane Monotherapy: Case Report and Review of the Literature

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.

Urinary glucocorticoid metabolites: biomarkers to classify adrenal incidentalomas?

OBJECTIVE

Total urinary cortisol metabolites represent cortisol production and metabolism. We hypothesized that to assay metabolites could add some information to the one provided by a sole cortisol assay.

DESIGN AND PATIENTS

We set up an inexpensive multiplex mass spectrometry assay to quantify cortisol metabolites. We investigated 43 patients with benign secreting (AT+) or silent (AT-) adrenal tumours compared to 48 lean (Nl) or 143 obese (Ob) subjects, and to 26 patients with a Cushing's disease (CD). The initial investigation included immunoreactive quantification of urinary free cortisol (UFC).

RESULTS

Cortisol metabolites were overexcreted in CD but not in Ob subjects. Nl and Ob were thus pooled in a control population (Ctl). Cortisol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE) excretions were significantly increased in AT compared to Ctl subjects, whereas immunoreactive UFC was similar. A logistic regression retaining cortisol, THF, and α- and β-cortolone as significant analytes allowed the construction of a receiver-operating characteristics (ROC) curve significantly better than the curve generated by cortisol alone (area under the curve (AUC) 0·927 vs 0·729, respectively; P < 0·0001). More importantly, although there was no significant difference between Ctl vs AT- subjects for cortisol metabolites, a logistic regression retaining cortisol, allo-THF, and α- and β-cortolone as significant analytes generated a ROC curve performing significantly better than cortisol alone (AUC 0·910 vs 0·635, respectively; P < 0·0001).

CONCLUSION

Cortisol metabolite excretion is modified in AT, including AT-, patients even without modification of UFC. Clinical usefulness of these biomarkers has to be investigated in prospective studies following up patients with AT.

Adrenocortical carcinoma

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.

Therapy of endocrine disease: steroidogenesis enzyme inhibitors in Cushing's syndrome

Steroidogenesis enzyme inhibitors are the mainstay of medical therapy in Cushing's syndrome (CS). Ketoconazole (KTZ) and metyrapone are the most commonly used agents. Although there is considerable experience of their use in individual specialist centres, these drugs have not been rigorously tested in prospective clinical trials. Clinicians face uncertainties and concerns with respect to the safety profile of these agents, and best means to monitor effect. We review steroidogenesis inhibitors in the management of CS, including older agents (KTZ, metyrapone, etomidate and mitotane) and those currently under development (LCI699, non-racemic KTZ), and offer a practical approach for their use in clinical practice.

Diagnosis, treatment and outcome of adrenocortical cancer

BACKGROUND

Adrenocortical cancer (ACC) is a rare disease with a dismal prognosis. The majority of patients are diagnosed with advanced disease and raise difficult management challenges.

METHODS

All references identified in PubMed, published between 2004 and 2014, using the keywords 'adrenocortical cancer' or 'adrenal surgery' or both, were uploaded into a database. The database was interrogated using keywords specific for each field studied.

RESULTS

In all, 2049 publications were identified. There is ongoing debate about the feasibility and oncological outcomes of laparoscopic adrenalectomy for small ACCs, and data derived from institutional case series have failed to provide an evidence level above expert opinion. The use of mitotane (1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2-dichloroethane) in combination with chemotherapy in the treatment of metastatic disease has been assessed in an international randomized trial (FIRM-ACT trial) involving patients with ACC. Based on this trial, mitotane plus etoposide, doxorubicin and cisplatin is now the established first-line cytotoxic therapy owing to a higher response rate and longer median progression-free survival than achieved with streptozocin-mitotane. For patients with tumours smaller than 5 cm and with no signs of lymph node or distant metastases, survival is favourable with a median exceeding 10 years. However, the overall 5-year survival rate for all patients with ACC is only 30 per cent.

CONCLUSION

Open and potentially laparoscopic adrenalectomy for selected patients is the main treatment for non-metastatic ACC, but the overall 5-year survival rate remains low.

Ovarian macrocysts and gonadotrope-ovarian axis disruption in premenopausal women receiving mitotane for adrenocortical carcinoma or Cushing's disease

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.

Short-term variation in plasma mitotane levels confirms the importance of trough level monitoring

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.

The lack of antitumor effects of o,p'DDA excludes its role as an active metabolite of mitotane for adrenocortical carcinoma treatment

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.

EJE prize 2014: current and evolving treatment options in adrenocortical carcinoma: where do we stand and where do we want to go?

Adrenocortical carcinoma (ACC) is not only a rare and heterogeneous disease but also one of the most aggressive endocrine tumors. Despite significant advances in the last decade, its pathogenesis is still only incompletely understood and overall therapeutic means are unsatisfactory. Herein, we provide our personal view of the currently available treatment options and suggest the following research efforts that we consider timely and necessary to improve therapy: i) for better outcome in localized ACCs, surgery should be restricted to experienced centers, which should then collaborate closely to address the key surgical questions (e.g. best approach and extent of surgery) in a multicenter manner. ii) For the development of better systemic therapies, it is crucial to elucidate the exact molecular mechanisms of action of mitotane. iii) A prospective trial is needed to address the role of cytotoxic drugs in the adjuvant setting in aggressive ACCs (e.g. mitotane vs mitotane+cisplatin). iv) For metastatic ACCs, new regimens should be investigated as first-line therapy. v) Several other issues (e.g. the role of radiotherapy and salvage therapies) might be answered - at least in a first step - by large retrospective multicenter studies. In conclusion, although it is unrealistic to expect that the majority of ACCs can be cured within the next decade, international collaborative efforts (including multiple translational and clinical studies) should allow significant improvement of clinical outcome of this disease. To this end, it might be reasonable to expand the European Network for the Study of Adrenal Tumors (ENSAT) to a truly worldwide international network - INSAT.

Adrenocortical carcinoma: the management of metastatic disease

Adrenocortical cancer is a rare malignancy. While surgery is the cornerstone of the management of localized disease, metastatic disease is hard to treat. Cytotoxic chemotherapy and mitotane have been utilized with a variable degree of benefit and few long-term responses. A growing understanding of the molecular pathogenesis of this malignancy as well as multidisciplinary and multi-institutional collaborative efforts will result in better defined targets and subsequently, effective novel therapies.

Review of therapeutic drug monitoring of anticancer drugs part 1--cytotoxics

Most anticancer drugs are characterised by a steep dose-response relationship and narrow therapeutic window. Inter-individual pharmacokinetic (PK) variability is often substantial. The most relevant PK parameter for cytotoxic drugs is the area under the plasma concentration versus time curve (AUC). Thus it is somewhat surprising that therapeutic drug monitoring (TDM) is still uncommon for the majority of agents. Goals of the review were to assess the rationale for more widely used TDM of cytotoxics in oncology. There are several reasons why TDM has never been fully implemented into daily oncology practice. These include difficulties in establishing appropriate concentration target ranges, common use of combination chemotherapies for many tumour types, analytical challenges with prodrugs, intracellular compounds, the paucity of published data from pharmacological trials and 'Day1 = Day21' administration schedules. There are some specific situations for which these limitations are overcome, including high dose methotrexate, 5-fluorouracil infusion, mitotane and some high dose chemotherapy regimens. TDM in paediatric oncology represents an important challenge. Established TDM approaches includes the widely used anticancer agents carboplatin, busulfan and methotrexate, with 13-cis-retinoic acid also recently of interest. Considerable effort should be made to better define concentration-effect relationships and to utilise tools such as population PK/PD models and comparative randomised trials of classic dosing versus pharmacokinetically guided adaptive dosing. There is an important heterogeneity among clinical practices and a strong need to promote TDM guidelines among the oncological community.

Practical treatment using mitotane for adrenocortical carcinoma

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.

Management of adrenal cancer: a 2013 update

Adrenocortical carcinoma (ACC) is a devastating tumor for either patients or their families because of short life expectancy and severe impact on quality of life. Due to the rarity of ACC, with a reported annual incidence of 0.5-2 cases per million population, progress in the development of treatment options beyond surgery has been limited. Up to now, no personalized approach of ACC therapy has emerged, apart from plasma level-guided mitotane therapy, and no simple targetable molecular event has been identified from preclinical studies. Complete surgical removal of ACC is the only potentially curative approach and has the most important impact on patient’s prognosis. Despite the limits of the available evidence, adjuvant mitotane therapy is currently recommended in many expert centers whenever the patients present an elevated risk of recurrence. The management of patients with recurrent and metastatic disease is challenging and the prognosis is often poor. Mitotane monotherapy is indicated in the management of patients with a low tumor burden and/or more indolent disease while patients whose disease show an aggressive behavior need cytotoxic chemotherapy. The treatment of patients with advanced ACC may include loco-regional approaches such as surgery and radiofrequency ablation in addition to systemic therapies. The present review provides an updated overview of the management of ACC patients following surgery and of the management of ACC patients with advanced disease.

Update in adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an orphan malignancy that has attracted increasing attention during the last decade. Here we provide an update on advances in the field since our last review published in this journal in 2006. The Wnt/β-catenin pathway and IGF-2 signaling have been confirmed as frequently altered signaling pathways in ACC, but recent data suggest that they are probably not sufficient for malignant transformation. Thus, major players in the pathogenesis are still unknown. For diagnostic workup, comprehensive hormonal assessment and detailed imaging are required because in most ACCs, evidence for autonomous steroid secretion can be found and computed tomography or magnetic resonance imaging (if necessary, combined with functional imaging) can differentiate benign from malignant adrenocortical tumors. Surgery is potentially curative in localized tumors. Thus, we recommend a complete resection including lymphadenectomy by an expert surgeon. The pathology report should demonstrate the adrenocortical origin of the lesion (eg, by steroidogenic factor 1 staining) and provide Weiss score, resection status, and quantitation of the proliferation marker Ki67 to guide further treatment. Even after complete surgery, recurrence is frequent and adjuvant mitotane treatment improves outcome, but uncertainty exists as to whether all patients benefit from this therapy. In advanced ACC, mitotane is still the standard of care. Based on the FIRM-ACT trial, mitotane plus etoposide, doxorubicin, and cisplatin is now the established first-line cytotoxic therapy. However, most patients will experience progress and require salvage therapies. Thus, new treatment concepts are urgently needed. The ongoing international efforts including comprehensive "-omic approaches" and next-generation sequencing will improve our understanding of the pathogenesis and hopefully lead to better therapies.

Mitotane levels predict the outcome of patients with adrenocortical carcinoma treated adjuvantly following radical resection

CONTEXT

Mitotane plasma concentrations ≥ 14 mg/l have been shown to predict tumor response and better survival in patients with advanced adrenocortical carcinoma (ACC). A correlation between mitotane concentrations and patient outcome has not been demonstrated in an adjuvant setting.

OBJECTIVE

To compare recurrence-free survival (RFS) in patients who reached and maintained mitotane concentrations ≥ 1 4 mg/l vs patients who did not.

DESIGN AND SETTING

Retrospective analysis at six referral European centers.

PATIENTS

Patients with ACC who were radically resected between 1995 and 2009 and were treated adjuvantly with mitotane targeting concentrations of 14-20 mg/l.

MAIN OUTCOME MEASURES

RFS (primary) and overall survival (secondary).

RESULTS

Of the 122 patients included, 63 patients (52%) reached and maintained during a median follow-up of 36 months the target mitotane concentrations (group 1) and 59 patients (48%) did not (group 2). ACC recurrence was observed in 22 patients of group 1 (35%) and 36 patients in group 2 (61%). In multivariable analysis, the maintenance of target mitotane concentrations was associated with a significantly prolonged RFS (hazard ratio (HR) of recurrence: 0.418, 0.22-0.79; P=0.007), while the risk of death was not significantly altered (HR: 0.59, 0.26-1.34; P=0.20). Grades 3-4 toxicity was observed in 11 patients (9%) and was managed with temporary mitotane discontinuation. None of the patients discontinued mitotane definitively for toxicity.

CONCLUSIONS

Mitotane concentrations ≥ 14 mg/l predict response to adjuvant treatment being associated with a prolonged RFS. A monitored adjuvant mitotane treatment may benefit patients after radical removal of ACC.

Management of adjuvant mitotane therapy following resection of adrenal cancer

Whenever adrenal cancer (ACC) is completely removed we should face the dilemma to treat by means of adjuvant therapy or not. In our opinion, adjuvant mitotane is the preferable approach in most cases because the majority of patients following radical removal of an ACC have an elevated risk of recurrence. A better understanding of factors that influence prognosis and response to treatment will help in stratifying patients according to their probability of benefiting from adjuvant mitotane, with the aim of sparing unnecessary toxicity to patients who are likely unresponsive. However, until significant advancements take place, we have to deal with uncertainty using our best clinical judgement and personal experience in the clinical decision process. In the present paper, we present the current evidence on adjuvant mitotane treatment and describe the management strategies of patients with ACC after complete surgical resection. We acknowledge the limit that most recommendations are based on personal experience rather than solid evidence.