Joyce O’Shaughnessy, MD, leads a discussion on SABCS 2021 updates from the SOFT and TEXT trials for premenopausal women with HR-positive breast cancer.
Joyce O’ Shaughnessy, MD: There was an update on the SOFT and TEXT clinical trial data from the San Antonio [Breast Cancer Symposium] this past year, looking mainly at the question of tamoxifen plus ovarian function suppression [OFS] with the LHRH [luteinizing hormone-releasing hormone] agonist, or the aromatase inhibitor exemestane [Aromasin] plus ovarian function suppression.
There are important prognostic variables that were carefully looked at in the SOFT and TEXT data. It was centrally done, with clinical and pathologic biomarkers. On each of these curves, the worse the prognosis, the more the benefit from the LHRH agonist, and the more the benefit from the aromatase inhibitor compared with tamoxifen. Ki67 is on the bottom left, and we can see the prognostic power of Ki67 in these patients with a Ki67 of 26% and higher having the worst. The patient we just talked about was mainly 10%, which is mainly in the really good risk group, but then she had some subclones that were at 20%. She had a bit of a mixed prognosis based on these central data from SOFT and TEXT.
We just had these great 13-year median follow-up updates. It’s good to see the long-term follow-up in these patients. About 60% or 65% of patients in the SOFT and TEXT trials were node-positive. You can see in the red box down at the bottom of everybody getting OFS and looking at exemestane vs tamoxifen. In the SOFT trial, the reduction in distant recurrence at 12 years was 1.9%, while in TEXT, it was 2.4%. The vast majority of patients in the SOFT and the TEXT trials were HER2-negative. There was a small cohort of patients who were HER2-positive.
In this analysis of overall survival, those patients were taken out of the analysis, so we’re looking here at the HER2-negative population. Down at the bottom is the bottom line looking at 12-year overall survival. There’s a 3.3% absolute improvement in overall survival using exemestane instead of tamoxifen along with OFS in these patients. It’s clearly very effective therapy that we have for patients, and they only got 5 years of therapy. Another question is duration. What do we do about duration in these high-risk patients? They only got 5-year therapy, but we can see here what the curves look like. With distant recurrence-free survival, it doesn’t look like there’s a big drop-off. Maybe there’s some carryover effect, but not a big drop-off in distant recurrence-free survival.
Transcript Edited for Clarity