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Post-progression data rarely reported in phase 3 metastatic breast cancer trials
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SAN FRANCISCO — Phase 3 clinical trials designed to evaluate survival in metastatic breast cancer rarely reported data on post-progression treatment, even though subsequent-line agents affect OS outcomes, according to study results presented at the Breast Cancer Symposium.
Jacques Raphael, MD, clinical fellow at Sunnybrook Odette Cancer Center in Toronto, and colleagues used PubMed to identify 110 randomized phase 3 clinical trials that evaluated survival in patients with metastatic breast cancer. All trials were published between 1994 and 2014.
A majority of the trials evaluated chemotherapy regimens (n=69; 63%), whereas 27 (25%) evaluated targeted agents and 14 (13%) evaluated endocrine therapies.
All of the targeted-agent trials utilized OS as a primary or secondary endpoint. OS was the primary or a secondary endpoint in 66 (97%) chemotherapy trials and 12 (86%) endocrine therapy trials.
Approximately 22% of trials in each category demonstrated an improvement in OS. However, only one trial in each category discussed post-progression survival and its effect on OS.
Less than 10% of chemotherapy and targeted therapy trials reported data on post-progression response and duration of response, and only two chemotherapy trials (3%) reported data on post-progression treatment resistance.
Ten chemotherapy trials (14%), three targeted-agent trials (11%) and two endocrine therapy trials (14%) reported the number of treatment lines utilized post progression.
“A clear paucity of post-progression treatment information is noted in the majority of phase 3 trials for metastatic breast cancer,” Raphael and colleagues wrote. “We do know that OS is directly affected by treatments used after progression. In order to assess the true clinical benefit of a new drug and a complete evaluation of OS outcome, a detailed collection of post-progression treatment information is required and should be mandated in metastatic breast cancer clinical studies.”
For more information:
Raphael J. Abstract #142. Presented at: Breast Cancer Symposium; Sept. 4-6, 2014; San Francisco.
Disclosure: One researcher reports honoraria/research funding from, as well as consultant/advisory and speakers’ bureau roles with Amgen, AstraZeneca, Boehringer Ingelheim, Eisai, Lilly, Novartis, Pfizer, Roche/Genentech and Sanofi Aventis.