A working group composed of breast cancer researchers have determined a list of appropriate endpoints for clinical trials of patients with metastatic breast cancer, according to data presented at the 2017 ASCO Annual Meeting.
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The National Cancer Institute (NCI)–sponsored steering committee endorsed endpoints sensitive to natural history of disease and availability of effective agents, as well as patient-reported outcomes (PROs) and expected toxicity burden. They further indicated that benchmarks should be reassessed based on the discovery of unique breast cancer subtypes and the availability of novel therapies, such as immunotherapy.
Due to the natural heterogeneity of metastatic breast cancer, clinical trials studying new agents in the disease have not consistently yielded Food and Drug Administration (FDA) approvals or led to significant practice changes. Because FDA guidelines governing clinical trial endpoints are not disease-specific, a metastatic breast cancer–specific working group led by Andrew D Seidman, MD, of Memorial Sloan Kettering Cancer Center (New York, NY), endeavored to develop disease-specific endpoints for clinical trials in this disease state.
The working group included oncologists, statisticians, disease advocates, and liaisons from the FDA and NCI. Participants conducted a literature review of 146 available papers. Data measurements included metastatic breast cancer natural history; human epidermal growth factor receptor 2 (HER2) status; and line of therapy. The working group also sought industry and patient perspectives on matters such as big data, real-world evidence, and PROs. The members of the working group anonymously voted to endorse key positions and statements.
Members of the working group voted on appropriate primary endpoints—either overall survival (OS) or progression-free survival (PFS)—based on disease subtype and expected length of post-progression survival (PPS). The committee agreed that OS was an appropriate endpoint for women with hormone receptor (HR)–negative and HER2–negative tumors, regardless of therapy line. For women with expected prolonged PPS, PFS was deemed an appropriate endpoint.
The committee members found little data regarding patient perceptions of PFS gain vs treatment-related toxicity, suggesting a need for PROs in this area. Approaches to capture grade and timing of toxicity through PROs were also suggested, to determine the value of therapies that prolong PFS without influencing OS.—Cameron Kelsall
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