Management of hepatic malignancies is a ubiquitous medical problem. Surgical resection of primary or metastatic liver cancer, with or without adjuvant chemotherapy, is the most effective method for enhancing survival; however, hepatic malignancies in the vast majority of patients are unresectable both at initial manifestation and at recurrence. In these patients, palliative cytoreductive therapies may help to retard tumor progression and therefore favorably alter the course of the disease. Since hepatic neoplasms are principally supplied by the hepatic artery, various arterially delivered cytotoxic agents have been developed to achieve these objectives. Recently, the Food and Drug Administration approved the transarterial administration of yttrium-90 microspheres for liver-directed therapy. Effective use of these devices requires knowledge of the accumulated clinical experience and a dedicated multidisciplinary effort to ensure optimal outcomes and avoid therapy-specific life-threatening complications.
Purpose Trastuzumab resistance has been linked to activation of the phosphoinositol 3-kinase (PI3K) pathway. Phosphatase and tensin homolog (PTEN) is a dual phosphatase that counteracts the PI3K function; PTEN loss leads to activation of the Akt cascade and the downstream mammalian target of rapamycin (mTOR). Preclinical studies demonstrated that mTOR inhibition sensitized the response to trastuzumab in mice with HER2 overexpressing and PTEN-deficient breast xenografts. Our trial evaluated the safety and efficacy of the combination of everolimus and trastuzumab in women with HER2-overexpressing metastatic breast cancer (MBC) that progressed on trastuzumab-based therapy. Patients and Methods This represents a pooled analysis (n = 47), stemming from two trials that occurred concurrently in The University of Texas MD Anderson Cancer Center, Beth Israel Deaconess Medical Center, and Dana-Farber Cancer Institute. Patients with HER2-overexpressing MBC who had progressed on trastuzumab-based therapy received trastuzumab every 3 weeks in combination with daily everolimus. Results Among 47 patients, the combination of everolimus and trastuzumab provided partial responses in seven patients (15%) and persistent stable disease (lasting 6 months or longer) in nine patients (19%), resulting in a clinical benefit rate of 34%. The median progression-free survival (PFS) was 4.1 month. Fatigue, infection, and mucositis were the predominant nonhematologic toxicities. Trastuzumab did not have significant influence on the pharmacokinetic profile of everolimus. Patients with PTEN loss demonstrated decreased overall survival (P = .048). However, PFS was not affected by PTEN loss. Conclusion Inhibition of mTOR results in clinical benefit and disease response in patients with trastuzumab-resistant HER2-overexpressing MBC.
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