Everolimus Exposure and Early Metabolic Response as Predictors of Treatment Outcomes in Breast Cancer Patients Treated with Everolimus and Exemestane.

BACKGROUND: Treating breast cancer patients with everolimus and exemestane can be challenging due to toxicity and suboptimal treatment responses. OBJECTIVE: We investigated whether everolimus exposure and early metabolic response are predictors for toxicity and effectiveness in these patients. PATIENTS AND METHODS: We performed pharmacokinetic assessments 14 and 35 days after starting treatment. [18F]fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) was performed at baseline, and 14 and 35 days after the start of the therapy. We recorded toxicity, defined as dose interventions within 3 months, and progression-free survival (PFS). RESULTS: Among 44 evaluable patients, the geometric mean (GM) Ctrough was higher in patients with toxicity compared to patients without (17.4 versus 12.3 µg/L (p = 0.02)). The optimal cut-off value to predict toxicity was Ctrough > 19.2 µg/L. GM Ctrough of patients with and without progressive disease (PD) within 3 months was not significantly different (12.0 versus 15.2 µg/L (p = 0.118)). In 28 evaluable patients, PD within 3 months could best be predicted using the percentage decrease in peak standardized uptake value normalized by lean body mass of the lesion with highest FDG uptake (SULpeak high) at day 14. Patients with <11% versus >11% decrease in SULpeak high at day 14 had a median PFS of 90 days versus 411 days, respectively (p = 0.0013) and more frequently had PD within 3 months: 70 vs 11%, respectively. CONCLUSIONS: Our results show that everolimus toxicity is related to everolimus Ctrough. No relation was observed between everolimus exposure and treatment effectiveness. An early FDG-PET can identify patients at high risk of nonresponse. These results warrant further validation. Clinicaltrials.gov identifier: NCT01948960.

ACTH-independent macronodular adrenocortical hyperplasia reveals prevalent aberrant in vivo and in vitro responses to hormonal stimuli and coupling of arginine-vasopressin type 1a receptor to 11ß-hydroxylase.

BACKGROUND: Adrenal Cushing's syndrome caused by ACTH-independent macronodular adrenocortical hyperplasia (AIMAH) can be accompanied by aberrant responses to hormonal stimuli. We investigated the prevalence of adrenocortical reactions to these stimuli in a large cohort of AIMAH patients, both in vivo and in vitro. METHODS: In vivo cortisol responses to hormonal stimuli were studied in 35 patients with ACTH-independent bilateral adrenal enlargement and (sub-)clinical hypercortisolism. In vitro, the effects of these stimuli on cortisol secretion and steroidogenic enzyme mRNA expression were evaluated in cultured AIMAH and other adrenocortical cells. Arginine-vasopressin (AVP) receptor mRNA levels were determined in the adrenal tissues. RESULTS: Positive serum cortisol responses to stimuli were detected in 27/35 AIMAH patients tested, with multiple responses within individual patients occurring for up to four stimuli. AVP and metoclopramide were the most prevalent hormonal stimuli triggering positive responses in vivo. Catecholamines induced short-term cortisol production more often in AIMAH cultures compared to other adrenal cells. Short- and long-term incubation with AVP increased cortisol secretion in cultures of AIMAH cells. AVP also increased steroidogenic enzyme mRNA expression, among which an aberrant induction of CYP11B1. AVP type 1a receptor was the only AVPR expressed and levels were high in the AIMAH tissues. AVPR1A expression was related to the AVP-induced stimulation of CYP11B1. CONCLUSIONS: Multiple hormonal signals can simultaneously induce hypercortisolism in AIMAH. AVP is the most prevalent eutopic signal and expression of its type 1a receptor was aberrantly linked to CYP11B1 expression.