Journal Article

A phase II study of combined fulvestrant and everolimus in patients with metastatic estrogen receptor (ER)-positive breast cancer after aromatase inhibitor (AI) failure

Stevens, Mark, Kadamyan-Melkumian, Vera, Romond, Edward, Massarweh, Suleiman, Black, Esther P., Van Meter, Emily, Shelton, Brent, Elledge, Richard

2014

Overview

Fulvestrant, which degrades ER, is used after AI failure in metastatic breast cancer but resistance develops quickly. We hypothesized that using everolimus to inhibit mTOR, a key signaling pathway in endocrine resistance, may delay fulvestrant resistance in patients and thus improve its efficacy. We conducted a phase II trial of combined fulvestrant and everolimus in postmenopausal women with disease progression or relapse after an AI. Primary endpoint was time to progression (TTP) and secondary endpoints included objective response rate, clinical benefit rate (CBR), safety, and biomarker correlates. Tumor blocks were collected and biopsy of accessible tumor was done for future biomarker analysis. Of 33 patients enrolled two were ruled ineligible after enrollment and were excluded from study analysis, for a total of 31 evaluable patients. Median age was 54 years (range 45–85). Prior therapy included tamoxifen (81 %), chemotherapy (71 %), with 26 % of patients having received 3 or more endocrine agents. Median TTP was 7.4 months (95 % CI 1.9–12.1) with an objective response rate of 13 % and CBR of 49 %. Of particular note, 32 % of patients exhibited de novo resistance to study treatment with disease progression as their best response. Most common adverse events (AEs) were elevated AST (87 %) and ALT (77 %), anemia (74 %), hyperglycemia (71 %), and hypercholesterolemia (68 %). Prominent clinical toxicities were mucositis (58 %), weight loss (48 %), and rash (42 %). Most AEs were grade 1 or 2 and largely reversible with infrequent need for everolimus dose reduction. To conclude, everolimus plus fulvestrant is effective after AI failure in heavily pretreated metastatic ER-positive breast cancer and has manageable toxicity. Further study of this combination is warranted in randomized studies. Since not all patients experience benefit, and in view of potential toxicities, biomarker examination is critical to help select patients most likely to benefit from this strategy in future studies.

• Publisher: Springer US,Springer,Springer Nature B.V
• Subject: Aged / Aged, 80 and over / Antineoplastic Agents, Hormonal - adverse effects / Antineoplastic Agents, Hormonal - therapeutic use / Antineoplastic Combined Chemotherapy Protocols - adverse effects / Antineoplastic Combined Chemotherapy Protocols - therapeutic use / Aromatase Inhibitors - therapeutic use / Breast cancer / Breast Neoplasms - drug therapy / Cancer / Cancer research / Cancer therapies / Care and treatment / Chemotherapy / Clinical Trial / Clinical trials / Drug resistance / Drug therapy / Endocrine therapy / Estradiol - adverse effects / Estradiol - analogs & derivatives / Estradiol - therapeutic use / Estrogen / Estrogens / Everolimus / Female / Humans / Immunosuppressive Agents - adverse effects / Immunosuppressive Agents - therapeutic use / Medical research / Medicine / Medicine & Public Health / Medicine, Experimental / Metastasis / Middle Aged / Neoplasm Recurrence, Local - drug therapy / Oncology / Phenols / Postmenopausal women / Product development / Receptors, Estrogen - metabolism / Sirolimus - adverse effects / Sirolimus - analogs & derivatives / Sirolimus - therapeutic use / Tamoxifen / TOR Serine-Threonine Kinases - antagonists & inhibitors / Treatment Failure