4CPS-027 Neoadjuvant double anti-Her2 blockade combined with anthracycline-free chemotherapy, results in locally advanced breast cancer

<h3>Background and Importance</h3> Double anti-Her2 blockade plus chemotherapy is a standard regimen in Her2+ locally advanced breast cancer (LABC). Docetaxel-carboplatin-trastuzumab-pertuzumab (TCHP) provides more anti-Her2 treatment, better pathological complete response (pCR) rates and less cardiotoxicity. It is not a very widespread option due to the risk of toxicity. <h3>Aim and Objectives</h3> Evaluate the efficacy and safety of TCHP by adding pegfilgrastim as primary prophylaxis. <h3>Material and Methods</h3> Describe our experience with neoadjuvant TCHP and pegfilgrastim combination between years 2017–2023 and compared with other schemes. <h3>Results</h3> 62 patients, median age 48 years; 61.3% were premenopausal; 54.8% were stage II and 45.2% were stage III; 67.7% had N+; 62.9% had RH-. A total of six cycles were completed in 85.5%; eight patients discontinued treatment due to toxicity. The most frequent adverse events were haematological (grade 3–4 in 8.1%) and digestive (grade 3–4 in 19.4%). No cardiac event was reported. 6.5% were hospitalised due to toxicity (3.2% febrile neutropenia). Dose reduction was needed in 43.5%. Clinical response occurred in 98.4% and radiological response in 87.1% (complete in 38.7%). pCR was obtained in 67.7% (66.7% in N+; 77.4% in RH-). Up to now, four patients have relapsed (three of them had pRC) and three have died. After median 24.5 months of follow-up, the median relapse-free and overall survival by Kaplan-Meier have not been reached. Cox regression shows that getting pCR does not impact survival. The odds ratio shows a higher proportion of obtaining pCR in the RH- and N+ subgroups, but without statistically significant differences. <h3>Conclusion and Relevance</h3> Our data of TCHP and pegfilgrastim shows considerable efficacy with an acceptable toxicity profile. The main advantage is the intensification of double lock dose, without anti Her2 window period, avoiding the addition of anthracyclines and, therefore, cardiac toxicity. pRC and toxicity profile results were better than other regimen proposed in other studies. Our data shows that pRC has no impact on survival. We assume a favourable association between pRC and N+ and HR-, although not statistically significant, probably due to the small amount of patients. Based on these favourable results, we believe that the priority use of TCHP-GCSF should be considered in the neoadjuvant treatment of Her2+ LABC. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest