Effectiveness of Everolimus Versus Endocrine Monotherapy or Chemotherapy Among HR+/HER2- mBC Patients With Multiple Metastatic Sites

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) C_trough 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 C_trough > 19.2 μg/L. GM C_trough 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 (SUL_{peak high}) at day 14. Patients with <11% versus >11% decrease in SUL_{peak 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 C_trough. 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.

Everolimus-induced pulmonary toxicity: Findings on 18F-FDG PET/CT imaging

The everolimus-exemestane combination is indicated in advanced breast cancer treatment and usually well tolerated. The objective of the study was to determine the frequency of everolimus lung side effects and investigate their imaging characteristics on positron emission tomography with 18F-fluoro-deoxy-glucose combined with computerized tomography (F-FDG PET/CT).Our single-center retrospective descriptive study systematically included all patients with metastatic breast cancer treated by this combination (n = 29 representing 57 F-FDG PET/CT). Number of segments involved was quantified. Maximum standardized uptake value (SUVmax), average standardized uptake value (SUVmean), metabolic target volume (MTV), and total lesion glycolysis (TLG) were measured. Severe pneumopathy was studied by subgroup analysis.Pleuroparenchymal anomalies rate detected on F-FDG PET/CT was 62%. Alveolar-interstitial lesions were mainly observed (89%) and affected 2.8 segments (0.5-11.5) with a median of 2 segments. S7 and S10 were the most involved segments with SUVmax 3.9 (1.3-8.8) and SUVmean 2.2 (0.7-4.9). Statistically significant difference (P = .02) was found with number of segment involved to characterize severe pneumopathy (average of 6.3 segments [2.5-11.5] vs 1.9 segments [0.5-8] for interstitial lung disease) but not with SUVmax, SUVmean, MTV, TLG (P = .14, 0.22, 0.22, and 0.17, respectively).The F-FDG PET/CT could highlight pulmonary everolimus side effects, with a typical imaging pattern: alveolar-interstitial opacities associated with moderate uptake, more or less extensive, mainly affecting the lower lobes. Rarely, a pseudotumoral aspect may be detected, corresponding to a pitfall. MTV or TLG showed a tendency to differentiate severe pneumopathy vs interstitial lung disease but no statistically significant differences was observed contrarily to the number of segments involved. Further studies are necessary to determine if the F-FDG PET/CT could early predict adverse effects of mTOR inhibitors.