Effect of Everolimus on Bone Marker Levels and Progressive Disease in Bone in BOLERO-2

Department of Endocrinology, Reproductive Medicine and Osteoporosis, Philipps-University of Marburg, Marburg, Germany (PH)
Journal of the National Cancer Institute (Impact Factor: 12.58). 02/2013; 105(9). DOI: 10.1093/jnci/djt026
Source: PubMed


Breast Cancer Trials of Oral Everolimus 2 (BOLERO-2), a phase III study in postmenopausal women with estrogen receptor-positive breast cancer progressing despite nonsteroidal aromatase inhibitor therapy, showed statistically significant benefits with adding everolimus to exemestane. Moreover, in preclinical studies, mammalian target of rapamycin inhibition was associated with decreased osteoclast survival and activity. Exploratory analyses in BOLERO-2 evaluated the effect of everolimus on bone marker levels and progressive disease in bone.Methods
Patients were treated with exemestane (25mg/day) and randomized (2:1) to everolimus (10mg/day; combination) or placebo (exemestane only). Exploratory endpoints included changes in bone turnover marker levels vs baseline and progressive disease in bone, defined as unequivocal progression of a preexisting bone lesion or the appearance of a new bone lesion.ResultsBaseline disease characteristics were well balanced between arms (N = 724); baseline bisphosphonate use was not (43.9% combination vs 54.0% exemestane only). At a median of 18 months of follow-up, median progression-free survival (primary endpoint) was statistically significantly longer with the combination vs exemestane only (Cox proportional hazard ratio = 0.45, 95% confidence interval = 0.38 to 0.54; log-rank, 1-sided P < .0001). Bone marker levels at 6 and 12 weeks increased with exemestane only, as expected, but decreased with the combination. The cumulative incidence rate of progressive disease in bone was lower in the combination arm. Bone-related adverse events occurred with similar frequency in both arms (3.3% combination vs 4.2% exemestane only).Conclusion
These exploratory analyses suggest that everolimus has beneficial effects on bone turnover and progressive disease in bone in patients receiving exemestane for hormone receptor-positive breast cancer progressing during/after nonsteroidal aromatase inhibitor therapy.

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    ABSTRACT: Background Postmenopausal women with hormone receptor–positive (HR+) breast cancer in whom disease progresses or there is recurrence while taking a nonsteroidal aromatase inhibitor (NSAI) are usually treated with exemestane (EXE), but no single standard of care exists in this setting. The BOLERO-2 trial demonstrated that adding everolimus (EVE) to EXE improved progression-free survival (PFS) while maintaining quality of life when compared with EXE alone. Because many women with HR+ advanced breast cancer are elderly, the tolerability profile of EVE plus EXE in this population is of interest. Patients and Methods BOLERO-2, a phase III randomized trial, compared EVE (10 mg/d) and placebo (PBO), both plus EXE (25 mg/d), in 724 postmenopausal women with HR+ advanced breast cancer recurring/progressing after treatment with NSAIs. Safety and efficacy data in elderly patients are reported at 18-month median follow-up. Results Baseline disease characteristics and treatment histories among the elderly subsets (≥ 65 years, n = 275; ≥ 70 years, n = 164) were generally comparable with younger patients. The addition of EVE to EXE improved PFS regardless of age (hazard ratio, 0.59 [≥ 65 years] and 0.45 [≥ 70 years]). Adverse events (AEs) of special interest (all grades) that occurred more frequently with EVE than with PBO included stomatitis, infections, rash, pneumonitis, and hyperglycemia. Elderly EVE-treated patients had similar incidences of these AEs as did younger patients but had more on-treatment deaths. Conclusion Adding EVE to EXE offers substantially improved PFS over EXE and was generally well tolerated in elderly patients with HR+ advanced breast cancer. Careful monitoring and appropriate dose reductions or interruptions for AE management are recommended during treatment with EVE in this patient population.
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    ABSTRACT: Oral everolimus (Afinitor(®)) in combination with exemestane is indicated for the treatment of hormone receptor-positive, human epidermal growth factor receptor (HER) 2-negative advanced breast cancer in postmenopausal women after failure of treatment with letrozole or anastrozole (in the USA) or after recurrence of progression following a nonsteroidal aromatase inhibitor (AI) in women without symptomatic visceral disease (in the EU). Everolimus, a selective inhibitor of mammalian target of rapamycin (mTOR), inhibits the downstream signalling events of the mTOR pathway. This review summarizes the pharmacology of everolimus and reviews its efficacy and tolerability when administered in combination with exemestane in postmenopausal women with oestrogen receptor-positive, HER2-negative advanced breast cancer refractory to nonsteroidal AIs. In the well-designed BOLERO-2 study, the addition of everolimus to exemestane was shown to significantly prolong progression-free survival in this patient population. However, treatment-emergent adverse events and treatment discontinuations occurred more frequently with combination therapy than with exemestane alone, suggesting a need for careful benefit/risk assessment prior to initiating therapy. Mature survival data from this study are awaited and additional studies would help to further demonstrate the benefit of combination therapy. Nevertheless, current evidence suggests that everolimus plus exemestane combination therapy may be a useful treatment option in patients with postmenopausal hormone receptor-positive, HER2-negative, advanced breast cancer refractory to nonsteroidal AIs.
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    ABSTRACT: Patients with breast cancer face substantial challenges to bone health from bone metastases, as well as from chemotherapy and endocrine therapies that generally elicit disease control at the cost of increased bone turnover. Consequently, maintaining bone health is of critical importance for these patients. Recently reported results from BOLERO-2 showed significant clinical benefits with adding everolimus to exemestane therapy in postmenopausal women with estrogen-receptor-positive breast cancer recurring or progressing despite nonsteroidal aromatase inhibitor therapy. Moreover, exploratory analyses from BOLERO-2 showed that adding everolimus may have beneficial effects on bone turnover and progressive disease in bone in this patient population. These results are supported by preclinical studies in which mTOR inhibition was associated with decreased osteoclast survival and activity. Thus, everolimus therapy may be able to ameliorate the negative effects of estrogen suppression on bone health. This review discusses the effects of mTOR inhibition on bone health during endocrine therapy.
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