The management of cancer patients has changed due to the considerably more frequent use of immune checkpoint inhibitors (ICPIs). However, the use of ICPI has a risk of side effects, particularly endocrine toxicity. Since the indications for ICPI are constantly expanding due to their efficacy, it is important that endocrinologists and oncologists know how to look for this type of toxicity and how to treat it when it arises. In view of this, the French Endocrine Society initiated the formulation of a consensus document on ICPI-related endocrine toxicity. In this paper, we will introduce data on the general pathophysiology of endocrine toxicity, and we will then outline expert opinion focusing primarily on methods for screening, management and monitoring for endocrine side effects in patients treated by ICPI. We will then look in turn at endocrinopathies that are induced by ICPI including dysthyroidism, hypophysitis, primary adrenal insufficiency and fulminant diabetes. In each chapter, expert opinion will be given on the diagnosis, management and monitoring for each complication. These expert opinions will also discuss the methodology for categorizing these side effects in oncology using ‘common terminology criteria for adverse events’ (CTCAE) and the difficulties in applying this to endocrine side effects in the case of these anti-cancer therapies. This is shown in particular by certain recommendations that are used for other side effects (high-dose corticosteroids, contraindicated in ICPI for example) and that cannot be considered as appropriate in the management of endocrine toxicity, as it usually does not require ICPI withdrawal or high-dose glucocorticoid intake.

Background Malignant pheochromocytoma and paraganglioma (MPP) are characterized by prognostic heterogeneity. Our objective was to look for prognostic parameters of overall survival in MPP patients. Patients and Methods Retrospective multicentric study of MPP characterized by a neckthoraco-abdomino-pelvic CT or MRI at the time of malignancy diagnosis in European centers between 1998 and 2010. Results We included 169 patients from 18 European centers. Main characteristics of MPP patients were: primary pheochromocytoma in 53% of patients, tumor or hormone-related symptoms in 57% or 58% of cases, positive plasma or urine hormones in 81% of patients, identification of a mutation in SDHB in 42 % of cases. Metastatic sites included the bone (64%), lymph node (40%), lung (29%) and liver (26%); mean time between initial and malignancy diagnosis was 43 months (0-614). Median follow-up was 68 months and median survival 6.7 years. Using univariate analysis, better survival was associated with head and neck paraganglioma, age <40 years, metanephrines <5-fold the upper limits of the normal range and low proliferative index. In multivariate analysis, hypersecretion (Hazard Ratio 3.02[1.65-5.55]; p:0.0004) was identified as independent significant prognostic factors of worst overall survival. Conclusions Our results do not confirm SDHB mutations as a major prognostic parameter in MPP and suggest additional key molecular events involved in MPP tumor progression. Aside from SDHB mutation, the biology of aggressive MPP remains to be understood.

Mitotane, 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane is the most effective medical therapy for adrenocortical carcinoma, but its molecular mechanism of action remains poorly understood. Although mitotane is known to have mitochondrial (mt) effects, a direct link to mt dysfunction has never been established. We examined the functional consequences of mitotane exposure on proliferation, steroidogenesis, and mt respiratory chain, biogenesis and morphology, in two human adrenocortical cell lines, the steroid-secreting H295R line and the non-secreting SW13 line. Mitotane inhibited cell proliferation in a dose-and a time-dependent manner. At the concentration of 50 mM (14 mg/l), which corresponds to the threshold for therapeutic efficacy, mitotane drastically reduced cortisol and 17-hydroxyprogesterone secretions by 70%. This was accompanied by significant decreases in the expression of genes encoding mt proteins involved in steroidogenesis (STAR, CYP11B1, and CYP11B2). In both H295R and SW13 cells, 50 mM mitotane significantly inhibited (50%) the maximum velocity of the activity of the respiratory chain complex IV (cytochrome c oxidase (COX)). This effect was associated with a drastic reduction in steady-state levels of the whole COX complex as revealed by blue native PAGE and reduced mRNA expression of both mtDNA-encoded COX2 (MT-CO2) and nuclear DNA-encoded COX4 (COX4I1) subunits. In contrast, the activity and expression of respiratory chain complexes II and III were unaffected by mitotane treatment. Lastly, mitotane exposure enhanced mt biogenesis (increase in mtDNA content and PGC1a (PPARGC1A) expression) and triggered fragmentation of the mt network. Altogether, our results provide first evidence that mitotane induced a mt respiratory chain defect in human adrenocortical cells.

Half of the therapy-naive patients with MPP achieved stable disease at 1 year. In symptom-free patients with MPP, a wait-and-see antitumor policy seems appropriate as first line. Modality for a prospective follow-up is proposed.