Data from a new study conducted by a team of researchers from the Lester and Sue Smith Breast Center at Baylor College of Medicine, indicates that combined targeted therapy without chemotherapy might work as a treatment option for some patients with HER2-positive breast cancer.
The phase II clinical trial findings were presented on behalf of the Translation Breast Cancer Research Condortium, led by Dr. Mothaffar Rimawi at the San Antonio Breast Cancer Symposium in Texas.
Evidence from early studies with mice suggested that certain patients with breast cancer who have tumors with a protein named HER-2 (which promotes breast cancer growth), may not need to undergo chemotherapy but can benefit from a combination targeted therapy instead.
“We first showed this favorable response to combination therapy in HER-2 positive tumors in mice. We then translated these findings in human trials, showing that, in fact, this combination of anti-HER2 therapy for only 12 weeks showed an excellent response in humans without having to go through chemotherapy, an often grueling and toxic aspect of treatment,” Dr. Rimawi explained in a news release.
Researchers examined the therapy outcome by duplicating the time of the combination to 24 weeks. A total of 94 patients were enrolled in this Phase II clinical trial and followed for 2 years. From this cohort, 33 were given the combination therapy for 12 weeks and 61 patients were given the same treatment for 24 weeks. The patient’s tumors had an average size of 5 cm and 65% were ER-positive. The combination therapy included lapatinib and trastuzamad. For the EH-positive tumours letrozole was added to the combination.
Results revealed differences between the two groups, with the 12-week group showing an overall response of 12% compared with 28% in the 24-week group. In the ER-positive cohort the complete response reached was 9% in the 12-week group and 33% in the 24-week group. In the ER-negative cohort, the complete response in the 12-week group and the 24-week group were 20% and 18%, respectively.
These findings suggest that a longer treatment improves response in HER-2 and estrogen receptor-positive patients.
In the news release, Dr. Kent Osborne, director of the NCI-designated Dan L. Duncan Cancer Center at Baylor, co-director of the Symposium, and study collaborator commented, “This approach needs more clinical study before we can say that some patients can be treated safely with this approach and now we are focusing our research to more clearly define which women do and do not need chemotherapy. This may spare some the cost and toxicity of chemotherapy”.