Trastuzumab improves PFS, OS in endometrial cancer subset
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The addition of trastuzumab to carboplatin and paclitaxel increased PFS and OS for women with advanced or recurrent HER2-positive uterine serous carcinoma, according to final results of a phase 2 study published in Clinical Cancer Research.
Researchers observed the greatest benefit among women with stage III and stage IV disease.
“Trastuzumab isn’t a new agent, especially for breast cancer, but this is the first time we are able to show efficacy in this subset of women with endometrial cancer,” Alessandro D. Santin, MD, professor of obstetrics, gynecology and reproductive sciences and co-chief of the section of gynecologic oncology at Yale University School of Medicine, told Healio. “Using only chemotherapy was the gold standard until now, and the scientific community was skeptical that this combination would work.”
Preliminary results of the randomized trial led to recognition of trastuzumab — a humanized monoclonal antibody that targets HER2 — in combination with carboplatin and paclitaxel as an alternative treatment regimen for advanced or recurrent HER-positive uterine serous carcinoma, a rare but highly aggressive form of endometrial cancer.
Santin and colleagues reported updated survival results of the trial, in which researchers randomly assigned 61 women with advanced or recurrent HER2-positive uterine serous carcinoma to carboplatin and paclitaxel for six cycles with or without trastuzumab followed by maintenance trastuzumab until progression or toxicity.
PFS served as the primary endpoint. OS and toxicity served as secondary endpoints.
Median follow-up was 25.9 months (range, 0.33-91.5).
Results showed that, among 58 evaluable women, trastuzumab significantly prolonged PFS compared with chemotherapy alone (median, 12.9 months vs. 8 months; HR = 0.46; 90% CI, 0.28-0.76). Overall, 43 women experienced disease progression and 38 women died.
Women with stage III and stage IV disease (n = 41) demonstrated the greatest PFS benefit with trastuzumab (median, 17.7 months vs. 9.3 months; HR = 0.44; 90% CI, 0.23-0.83). Trastuzumab also extended PFS among 17 women with recurrent disease (median, 9.2 months vs. 7 months; HR = 0.12; 90% CI, 0.03-0.48).
Researchers reported median OS of 29.6 months with trastuzumab vs. 24.4 months with chemotherapy alone (HR = 0.58; 90% CI, 0.34-0.99), with the most notable OS benefit again among women with stage III and stage IV disease (not reached vs. 24.4 months; HR = 0.49; 90% CI, 0.25-0.97).
Toxicity appeared similar in both groups.
“This is going to become the new standard of care, I have no doubt about that,” Santin told Healio. “This is a very rare subtype of disease, but we were still able to get over 60 patients on trial. We are planning a phase 3 study, and I am confident that we will see similar results.
“We have not seen any significant toxicity, and we are confident in this agent because it has been around for 30 years,” Santin added. “It took 20 years to get to this point, but I am very pleased with how this turned out.”
For more information:
Alessandro D. Santin, MD, can be reached at Smilow Cancer Hospital at Yale New Haven, 35 Park St., Suite North Pavilion 8, New Haven, CT, 06511; email: alessandro.santin@yale.edu.
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