Neoadjuvant treatment with trastuzumab, pertuzumab and paclitaxel in women with HER2+ non-malignant breast cancer can achieve a high rate of pathological complete response (pCR).
A small study of 18 patients in Sydney who were in a position to self-fund the dual anti-HER2 treatment and had definitive surgery found the overall pCR rate was 68%.
This compares favourably with a previously reported rate of 46% in a larger prospective randomised trial, according to study investigators from Sydney Adventist Hospital .
Patients in the first Australian trial received four neoadjuvant cycles of trastuzumab and pertuzumab plus weekly paclitaxel for 12 weeks.
Most women received wide local excision with sentinel node biopsy (62%) or axillary clearance (16%); 11% had mastectomy with sentinel node biopsy and 11% had mastectomy plus axillary clearance.
Fifty-four percent of the pCR patients had no residual DCIS. Of the patients who had N1 disease, 88% of patients had total pCR in the axilla and the breast.
No pretreatment characteristic analysed was predictive of pCR.
“The combination of trastuzumab and pertuzumab appears to provide complementary action in shutting down HER2 signaling pathways earlier,” the study investigators reported in the Asia-Pacific Journal of Clinical Oncology.
All patients had frequently occurring but manageable side effects such as alopecia, diarrhoea, stomatitis, fatigue, nausea and vomiting.
Grade 3 and higher adverse effects seemed to be related predominantly to the taxane therapy.
While not currently funded on the PBS in Australia, the study authors said the triple therapy was gaining traction in this patient group around the world.
“This is the first reported Australian experience using neoadjuvant triple therapy for HER2 positive nonmetastatic breast cancer … National funding models need to be considered to be more readily accessible to the general Australian public,” they concluded.
A larger, prospective trial on the safety and effectiveness of pertuzumab in the neoadjuvant setting for HER2 positive non-metastatic breast cancer was expected to complete later this year, they added.