Impact of relative dose intensity on pathologic complete response in human epidermal growth factor receptor 2 positive breast cancer patients receiving neoadjuvant TCHP

Purpose: The standard of care for locally advanced, human epidermal growth factor receptor 2 positive (HER2+) breast cancer includes neoadjuvant chemotherapy with docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP). Many patients do not receive the full course of therapy due to various complications, possibly affecting the potential to achieve a pathologic complete response (pCR). The amount of therapy received is typically measured by relative dose intensity (RDI). This study aimed to evaluate pCR rates in patients receiving optimal and suboptimal RDI TCHP. Methods: This study was a retrospective chart review of patients treated between 2014 and 2021 at UK HealthCare. Patients included were 18 years of age or older with HER2+ breast cancer and received at least one cycle of neoadjuvant TCHP. The primary objective compared pCR rates in patients receiving ≥ 85% RDI or <85% RDI. Secondary objectives included pCR rates based on clinical stage, age, body mass index, or hormone receptor status; factors leading to discontinuation or delay in treatment; and impact of dose reductions and delays on pCR. Results: A total of 101 patients were included and divided into two cohorts: 54 patients received ≥ 85% RDI and 47 patients received <85% RDI. Patients who received ≥ 85% total RDI had an approximate increase of 17% in pCR rates (59.3% vs 42.6%, p = 0.11). Additionally, 82% of patients experienced a dose delay or adjustment. Conclusions: Patients who received ≥ 85% RDI had increased pCR rates compared to patients receiving <85% RDI. A larger patient population is needed to formulate definitive conclusions on the impact of RDI and pCR rates.