INTRODUCTION: Trastuzumab deruxtecan (T-DXd) has revolutionised treatment for metastatic breast cancer (MBC). While effective, its high cost and toxicities, such as fatigue and nausea, pose challenges. METHOD: Medical records from the Joint Breast Cancer Registry in Singapore were used to study MBC patients treated with T-DXd (February 2021-June 2024). This study was conducted to address whether reducing dose intensity and density may have an adverse effect on treatment outcomes. RESULTS: Eighty-seven MBC patients were treated with T-DXd, with a median age of 59 years. At the time of data cutoff, 32.1% of patients were still receiving T-DXd. Over half (54%) of the patients received treatment with an initial relative dose intensity (RDI) of <;85%. Overall median real-world progression-free survival (rwPFS) was 8.1 months. rwPFS was similar between RDI groups (<85%: 8.7 months, <85%: 8.1 months, P=0.62). However, human epidermal growth receptor 2 (HER2)-positive patients showed significantly better rwPFS outcomes compared to HER2-low patients (8.8 versus 2.5 months, P<0.001). Only 16% with central nervous system (CNS) involvement had CNS progressive disease on treatment. No significant progression-free survival (PFS) differences were found between patients with or without CNS disease, regardless of RDI groups. Five patients (5.7%) developed interstitial lung disease (ILD), with 3 (3.4%) having grade 3 events. Two required high-dose steroids and none were rechallenged after ILD. There were no fatalities. CONCLUSION Our study demonstrated that reduced dose intensity and density had no significant impact on rwPFS or treatment-related toxicities. Furthermore, only 5.7% of patients developed ILD. T-Dxd provided good control of CNS disease, with 82% of patients achieving CNS disease control.
Humans ; Female ; Breast Neoplasms/mortality* ; Middle Aged ; Trastuzumab/adverse effects* ; Aged ; Adult ; Singapore/epidemiology* ; Antineoplastic Agents, Immunological/adverse effects* ; Camptothecin/adverse effects* ; Immunoconjugates/adverse effects* ; Retrospective Studies ; Progression-Free Survival ; Receptor, ErbB-2/metabolism* ; Neoplasm Metastasis ; Dose-Response Relationship, Drug ; Treatment Outcome ; Registries

Purpose: Higher neutrophil-lymphocyte ratio (NLRs) indicate a pro-inflammatory state and are associated with poor survival. Conversely, higher albumin-globulin ratio (AGRs) may be associated with improved prognosis. We aimed to investigate the association between NLR and AGR and prognosis and survival in patients with breast cancer. Methods: This retrospective study included all patients with stage I–III breast cancer between 2011 and 2017 in Singapore General Hospital and National Cancer Center Singapore.Multivariate logistic regression analysis of NLR, AGR, age, stage, grade, and subtype was performed. Survival data between groups were compared using Cox regression analysis and log-rank tests. Results: A total of 1,188 patients were included, of whom 323 received neoadjuvant chemotherapy (NACT) and 865 underwent upfront surgery. In patients who underwent NACT, a higher AGR was significantly associated with a higher pCR rate (cut-off > 1.28; odds ratio [OR], 2.03; 95% confidence interval [CI], 1.13–3.74; p = 0.020), better DFS (cut off > 1.55; hazard ratio [HR], 0.37; 95% CI, 0.16–0.85; p = 0.019), and better CSS (cut off > 1.46; HR, 0.39; 95% CI, 0.17–0.92; p = 0.031). Higher NLR was significantly associated with worse DFS (cut off > 4.09; HR, 1.77; 95% CI, 1.07–2.91; p = 0.026) and worse CSS (cut off > 4.09; HR, 1.98; 95% CI, 1.11–3.53; p = 0.021). In patients who underwent upfront surgery, higher AGR correlated with significantly better OS (cut off > 1.17; HR, 0.54; 95% CI, 0.36–0.82; p = 0.004) and higher NLR correlated with worse OS (cut off > 2.38; HR, 1.63; 95% CI, 1.09–2.44; p = 0.018). Conclusion NLR and AGR are useful in predicting the response to NACT as well as prognosis of patients with breast cancer. Further studies are needed to explore their value in clinical decision making.