21P - Neoadjuvant trastuzumab and pertuzumab in real-world data population in two medical institutions in Portugal

Background

Neoadjuvant treatment (NAT) refers to the treatment that is administered before surgery for the treatment of cancer. For the last few years the medical community noticed that achieving complete pathological response (pCR), for HER2+ breast cancer patients, after the NAT equates to a long-term surrogate point, which has pushed for the development of treatment strategies based of neoadjuvant use of trastuzumab and pertuzumab. We implemented an institutional protocol in 2018 to treat HER2+ breast cancer patients that had tumours larger than 2cm and/or axillary disease that had had included anthracyclins, taxanes, trastuzumab and pertuzumab on their NAT regimen. The main goal was to prospectively analyse the effect of this neoadjuvant regimen on pCR (ypT0/is, ypN0/is), as well as on how often does NAT help with breast conservation.

Methods

This non-randomized prospective study was performed in two medical oncology departments in Portugal. It included HER2+ breast cancer patients that had tumours larger than 2cm and/or axillary disease that have been being treated since 2018. These patients were put on the following treatment scheme: 4 cycles of doxorrubicin and cyclofosfamid, followed by 12 doses of standard paclitaxel plus four standard trastuzumab and pertuzumab cycles.

Results

A total of 38 patients were included in the study. The median age: 54 years; 17 patients had stage II cancer and 21 patients stage III. 26 patients had a ki67 >20%. pCR was achieved in 60,5% of the patients, 58,6 % in the hormonal receptor (HR) positive subgroup and 66,7% in HR-negative patients. 57,9% of the patients received breast conservative surgery and 65,9% received axillary dissection. Only one patient didn’t complete the protocol by own choice and no cardiac toxicity was detected on any patient.

Conclusions

Our results are consistent with those published in previous studies in terms of pCR rate and toxicity, however there was a high number of axillar dissections and for that reason we are working in an institutional protocol for the management of the axillary disease after NAT. Long term follow up is necessary to understand the real impact of pCR and to search for predictive indicators of the response to NAT.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.