Medical management of adrenocortical carcinoma: Current recommendations, new therapeutic options and future perspectives

Live birth after in-vitro maturation of oocytes in a patient with specific ovarian insufficiency caused by long-term mitotane treatment for adrenocortical carcinoma

RESEARCH QUESTION

How should the fertility of a woman with persistent specific ovarian dysfunction after long-term mitotane exposure be managed?

DESIGN

Case report. A 33-year-old woman who underwent surgery for adrenocortical carcinoma and treated with mitotane was referred for infertility. She rapidly became amenorrhoeic while taking mitotane, a condition that persisted for 5 years after cessation. Repeated serum hormone evaluation showed collapsed androgen levels, low oestradiol, high gonadotrophins (LH 69 and 63; FSH 23 and 43 IU/l), relatively high inhibin B level and slightly decreased anti-Müllerian hormone levels (1.4 and 0.7 ng/ml). An ultrasound scan revealed an antral follicle count of 13, contrasting with high serum gonadotrophin levels. After failure to obtain follicular growth after ovarian stimulation, in-vitro maturation (IVM) of immature oocytes aspirated from the antral follicles was carried out for microinjection with the spermatozoa of the patient's partner.

RESULTS

Two cycles of unstimulated egg retrieval were carried out, producing seven IVM oocytes, which were microinjected. A total of three cleavage-stage embryos were vitrified and unsuccessfully transferred after endometrial preparation using hormone replacement therapy (HRT). After a 20-month break, two new attempts were carried out under HRT with the aim of achieving a fresh embryo transfer. The last attempt succeeded after transfer of a single day-2 embryo, and the patient delivered a healthy baby.

CONCLUSION

Persistent specific impaired ovarian function 5 years after withdrawal of mitotane, and the first live birth after IVM in this situation, are reported. The question of fertility preservation before long-term mitotane treatment is raised.

The Challenging Pharmacokinetics of Mitotane: An Old Drug in Need of New Packaging

Adrenocortical carcinoma (ACC) is a malignant tumor originating from the adrenal gland cortex with a heterogeneous but overall dismal prognosis in advanced stages. For more than 50 years, mitotane has remained a cornerstone for the treatment of ACC as adjuvant and palliative therapy. It has a very poor aqueous solubility of 0.1 mg/l and high partition coefficient in octanol/water (log P) value of 6. The commercially available dosage form is 500 mg tablets (Lysodren^®). Even at doses up to 6 g/day (12 tablets in divided doses) for several months, > 50% patients do not achieve therapeutic plasma concentration > 14 mg/l due to poor water solubility, large volume of distribution and inter/intra-individual variability in bioavailability. This article aims to give a concise update of the clinical challenges associated with the administration of high-dose mitotane oral therapy which encompass the issues of poor bioavailability, difficult-to-predict pharmacokinetics and associated adverse events. Moreover, we present recent efforts to improve mitotane formulations. Their success has been limited, and we therefore propose an injectable mitotane formulation instead of oral administration, which could bypass many of the main issues associated with high-dose oral mitotane therapy. A parenteral administration of mitotane could not only help to alleviate the adverse effects but also circumvent the variable oral absorption, give better control over therapeutic plasma mitotane concentration and potentially shorten the time to achieve therapeutic drug plasma concentrations considerably.

Mitotane as tablet form is currently the standard treatment for adrenocortical carcinoma. It has been used for 5 decades but suffers from highly variable responses in patients, subsequent adverse effects and overall lower response rate. This can be fundamentally linked to the exceedingly poor water solubility of mitotane itself. In terms of enhancing water solubility, a few research groups have attempted to develop better formulations of mitotane to overcome the issues associated with tablet dosage form. However, the success rate was limited, and these formulations did not make it into the clinics. In this article, we have comprehensively reviewed the properties of these formulations and discuss the reasons for their limited utility. Furthermore, we discuss a recently developed mitotane nanoformulation that led us to propose a novel approach to mitotane therapy, where intravenous delivery supplements the standard oral administration. With this article, we combine the current state of knowledge as a single piece of information about the various problems associated with the use of mitotane tablets, and herein we postulate the development of a new injectable mitotane formulation, which can potentially circumvent the major problems associated to mitotane's poor water solubility.