Joyce O'Shaughnessy, MD: This young perimenopausal woman, age 54, otherwise healthy, presented with a pretty serious breast cancer. It was estrogen receptor-positive, strongly HER2 [human epidermal growth factor receptor 2]-positive, 3+ score by IHC [immunohistochemistry], grade 3 disease, nodes positive at presentation, and a pretty substantially sized cancer. That is a prognosis that definitely is associated with risk, and you’re really thinking about utilizing the very best therapies that you have. Before the introduction of trastuzumab, her risk of death from breast cancer would have been very high, probably somewhere in excess of 50%, closer probably to a 70%, 80% chance of dying eventually of breast cancer because the recurrences can be late.
With the introduction of the trastuzumab as adjuvant therapy, she probably would be looking more at about an 80% chance of remaining disease free for long term. With the then introduction of pertuzumab in the overall trial, like the APHINITY trial, that was further improved, probably up to the 85%-plus, 88% chance. Switching then to the T-DM1 [trastuzumab emtansine] in the adjuvant setting when she did not have a pathologic complete response, those patients in the KATHERINE trial, that resets the prognosis because now you know something, which is that she responded to the TCHP [docetaxel, carboplatin, trastuzumab, pertuzumab], but she did not have a pathologic complete response. So she was still going to be looking at a 20%, 25% chance of recurrence with just trastuzumab and pertuzumab.
Switching to the T-DM1 when she had residual disease took her from a disease-free survival rate of the mid-to-high 70% range, up to the mid-to-high 80% chance of remaining disease free. Unfortunately, that still leaves her with risk. So she does have risk; she still probably has somewhere between a 10% and 15% residual risk of recurrence.
Transcript edited for clarity.
Case: A 54-Year-Old Woman With Stage 2HER2+ Breast Cancer
Treatment and Follow-Up