{
  "abstract": "Background and Importance Treatment with dual HER2 blockade, combining Trastuzumab and Pertuzumab with chemotherapy, is currently the therapeutic option in the neoadjuvant setting for patients with early-stage disease and HER2 overexpression.Aim and Objectives This study aimed to evaluate the use of dual HER2 blockade in real-world clinical practice. The primary objective was to determine the rate of pathological complete response (pCR). Secondary objectives included assessing factors influencing pCR, progression-free survival time and overall survival.Material and Methods Patients with early-stage HER2-positive breast cancer treated between 2017 and 2024 were retrospectively analysed. Pathological complete response was evaluated, and the impact of various influencing factors was assessed using Pearson’s Chi-squared or Fisher’s exact tests, with p-values adjusted using the Benjamini–Hochberg method. Logistic regression was used to examine associations between pCR and significant variables. Statistical analyses were performed using R.Results Of the 84 patients included, 44 (52.4%; 95% CI: 41.7%–63.1%) achieved a pCR. In the overall cohort, pCR was significantly associated with HR status (p = 0.0036) and HER2 expression (p = 0.00065), with lower pCR rates observed in HR-positive and HER2 IHC 2+/FISH+ tumours. In multivariable analysis, HR-negative status (OR: 7.6; 95% CI: 2.6–26.6) and HER2 IHC 3+ expression (OR: 6.6; 95% CI: 1.6–26.6) were independently associated with a higher likelihood of achieving pCR. Tumour size, nodal involvement, histological grade, Ki-67 expression, and menopausal status were not significantly associated with pCR. After a median follow-up of 45.9 months, the number of disease progression or death events was insufficient to estimate progression-free survival.Conclusion and Relevance Approximately half of the patients achieved pCR with neoadjuvant dual HER2 blockade, showing a positive association between HR negativity and treatment response. Additionally, a significant correlation was observed between lower HER2 expression (IHC 2+/FISH+) and reduced response rates. The average follow-up duration has not yet allowed for the estimation of median progression-free survival or overall survival.Conflict of Interest No conflict of interest",
  "authors": [
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "T Ferreira"
    },
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "AM Soares"
    },
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "MDS Lourenço"
    },
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "B Resende"
    },
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "S Bastos"
    },
    {
      "affiliations": [
        "Hospital Garcia De Orta- Almada-Seixal Local Health Unit, Pharmacy, Almada, Portugal"
      ],
      "name": "A Alcobia"
    }
  ],
  "title": "4CPS-224 Real-world effectiveness of neoadjuvant dual HER2 blockade in early–stage her2–positive breast cancer",
  "uid": "e4986e64-8f46-54af-b05d-429a68597e0c"
}